Source file src/net/http/h2_bundle.go

     1  //go:build !nethttpomithttp2
     2  
     3  // Code generated by golang.org/x/tools/cmd/bundle. DO NOT EDIT.
     4  //   $ bundle -o=h2_bundle.go -prefix=http2 -tags=!nethttpomithttp2 golang.org/x/net/http2
     5  
     6  // Package http2 implements the HTTP/2 protocol.
     7  //
     8  // This package is low-level and intended to be used directly by very
     9  // few people. Most users will use it indirectly through the automatic
    10  // use by the net/http package (from Go 1.6 and later).
    11  // For use in earlier Go versions see ConfigureServer. (Transport support
    12  // requires Go 1.6 or later)
    13  //
    14  // See https://http2.github.io/ for more information on HTTP/2.
    15  //
    16  // See https://http2.golang.org/ for a test server running this code.
    17  //
    18  // Copyright 2024 The Go Authors. All rights reserved.
    19  // Use of this source code is governed by a BSD-style
    20  // license that can be found in the LICENSE file.
    21  //
    22  
    23  package http
    24  
    25  import (
    26  	"bufio"
    27  	"bytes"
    28  	"compress/gzip"
    29  	"context"
    30  	"crypto/rand"
    31  	"crypto/tls"
    32  	"encoding/binary"
    33  	"errors"
    34  	"fmt"
    35  	"io"
    36  	"io/fs"
    37  	"log"
    38  	"math"
    39  	"math/bits"
    40  	mathrand "math/rand"
    41  	"net"
    42  	"net/http/httptrace"
    43  	"net/textproto"
    44  	"net/url"
    45  	"os"
    46  	"reflect"
    47  	"runtime"
    48  	"sort"
    49  	"strconv"
    50  	"strings"
    51  	"sync"
    52  	"sync/atomic"
    53  	"time"
    54  
    55  	"golang.org/x/net/http/httpguts"
    56  	"golang.org/x/net/http2/hpack"
    57  	"golang.org/x/net/idna"
    58  )
    59  
    60  // The HTTP protocols are defined in terms of ASCII, not Unicode. This file
    61  // contains helper functions which may use Unicode-aware functions which would
    62  // otherwise be unsafe and could introduce vulnerabilities if used improperly.
    63  
    64  // asciiEqualFold is strings.EqualFold, ASCII only. It reports whether s and t
    65  // are equal, ASCII-case-insensitively.
    66  func http2asciiEqualFold(s, t string) bool {
    67  	if len(s) != len(t) {
    68  		return false
    69  	}
    70  	for i := 0; i < len(s); i++ {
    71  		if http2lower(s[i]) != http2lower(t[i]) {
    72  			return false
    73  		}
    74  	}
    75  	return true
    76  }
    77  
    78  // lower returns the ASCII lowercase version of b.
    79  func http2lower(b byte) byte {
    80  	if 'A' <= b && b <= 'Z' {
    81  		return b + ('a' - 'A')
    82  	}
    83  	return b
    84  }
    85  
    86  // isASCIIPrint returns whether s is ASCII and printable according to
    87  // https://tools.ietf.org/html/rfc20#section-4.2.
    88  func http2isASCIIPrint(s string) bool {
    89  	for i := 0; i < len(s); i++ {
    90  		if s[i] < ' ' || s[i] > '~' {
    91  			return false
    92  		}
    93  	}
    94  	return true
    95  }
    96  
    97  // asciiToLower returns the lowercase version of s if s is ASCII and printable,
    98  // and whether or not it was.
    99  func http2asciiToLower(s string) (lower string, ok bool) {
   100  	if !http2isASCIIPrint(s) {
   101  		return "", false
   102  	}
   103  	return strings.ToLower(s), true
   104  }
   105  
   106  // A list of the possible cipher suite ids. Taken from
   107  // https://www.iana.org/assignments/tls-parameters/tls-parameters.txt
   108  
   109  const (
   110  	http2cipher_TLS_NULL_WITH_NULL_NULL               uint16 = 0x0000
   111  	http2cipher_TLS_RSA_WITH_NULL_MD5                 uint16 = 0x0001
   112  	http2cipher_TLS_RSA_WITH_NULL_SHA                 uint16 = 0x0002
   113  	http2cipher_TLS_RSA_EXPORT_WITH_RC4_40_MD5        uint16 = 0x0003
   114  	http2cipher_TLS_RSA_WITH_RC4_128_MD5              uint16 = 0x0004
   115  	http2cipher_TLS_RSA_WITH_RC4_128_SHA              uint16 = 0x0005
   116  	http2cipher_TLS_RSA_EXPORT_WITH_RC2_CBC_40_MD5    uint16 = 0x0006
   117  	http2cipher_TLS_RSA_WITH_IDEA_CBC_SHA             uint16 = 0x0007
   118  	http2cipher_TLS_RSA_EXPORT_WITH_DES40_CBC_SHA     uint16 = 0x0008
   119  	http2cipher_TLS_RSA_WITH_DES_CBC_SHA              uint16 = 0x0009
   120  	http2cipher_TLS_RSA_WITH_3DES_EDE_CBC_SHA         uint16 = 0x000A
   121  	http2cipher_TLS_DH_DSS_EXPORT_WITH_DES40_CBC_SHA  uint16 = 0x000B
   122  	http2cipher_TLS_DH_DSS_WITH_DES_CBC_SHA           uint16 = 0x000C
   123  	http2cipher_TLS_DH_DSS_WITH_3DES_EDE_CBC_SHA      uint16 = 0x000D
   124  	http2cipher_TLS_DH_RSA_EXPORT_WITH_DES40_CBC_SHA  uint16 = 0x000E
   125  	http2cipher_TLS_DH_RSA_WITH_DES_CBC_SHA           uint16 = 0x000F
   126  	http2cipher_TLS_DH_RSA_WITH_3DES_EDE_CBC_SHA      uint16 = 0x0010
   127  	http2cipher_TLS_DHE_DSS_EXPORT_WITH_DES40_CBC_SHA uint16 = 0x0011
   128  	http2cipher_TLS_DHE_DSS_WITH_DES_CBC_SHA          uint16 = 0x0012
   129  	http2cipher_TLS_DHE_DSS_WITH_3DES_EDE_CBC_SHA     uint16 = 0x0013
   130  	http2cipher_TLS_DHE_RSA_EXPORT_WITH_DES40_CBC_SHA uint16 = 0x0014
   131  	http2cipher_TLS_DHE_RSA_WITH_DES_CBC_SHA          uint16 = 0x0015
   132  	http2cipher_TLS_DHE_RSA_WITH_3DES_EDE_CBC_SHA     uint16 = 0x0016
   133  	http2cipher_TLS_DH_anon_EXPORT_WITH_RC4_40_MD5    uint16 = 0x0017
   134  	http2cipher_TLS_DH_anon_WITH_RC4_128_MD5          uint16 = 0x0018
   135  	http2cipher_TLS_DH_anon_EXPORT_WITH_DES40_CBC_SHA uint16 = 0x0019
   136  	http2cipher_TLS_DH_anon_WITH_DES_CBC_SHA          uint16 = 0x001A
   137  	http2cipher_TLS_DH_anon_WITH_3DES_EDE_CBC_SHA     uint16 = 0x001B
   138  	// Reserved uint16 =  0x001C-1D
   139  	http2cipher_TLS_KRB5_WITH_DES_CBC_SHA             uint16 = 0x001E
   140  	http2cipher_TLS_KRB5_WITH_3DES_EDE_CBC_SHA        uint16 = 0x001F
   141  	http2cipher_TLS_KRB5_WITH_RC4_128_SHA             uint16 = 0x0020
   142  	http2cipher_TLS_KRB5_WITH_IDEA_CBC_SHA            uint16 = 0x0021
   143  	http2cipher_TLS_KRB5_WITH_DES_CBC_MD5             uint16 = 0x0022
   144  	http2cipher_TLS_KRB5_WITH_3DES_EDE_CBC_MD5        uint16 = 0x0023
   145  	http2cipher_TLS_KRB5_WITH_RC4_128_MD5             uint16 = 0x0024
   146  	http2cipher_TLS_KRB5_WITH_IDEA_CBC_MD5            uint16 = 0x0025
   147  	http2cipher_TLS_KRB5_EXPORT_WITH_DES_CBC_40_SHA   uint16 = 0x0026
   148  	http2cipher_TLS_KRB5_EXPORT_WITH_RC2_CBC_40_SHA   uint16 = 0x0027
   149  	http2cipher_TLS_KRB5_EXPORT_WITH_RC4_40_SHA       uint16 = 0x0028
   150  	http2cipher_TLS_KRB5_EXPORT_WITH_DES_CBC_40_MD5   uint16 = 0x0029
   151  	http2cipher_TLS_KRB5_EXPORT_WITH_RC2_CBC_40_MD5   uint16 = 0x002A
   152  	http2cipher_TLS_KRB5_EXPORT_WITH_RC4_40_MD5       uint16 = 0x002B
   153  	http2cipher_TLS_PSK_WITH_NULL_SHA                 uint16 = 0x002C
   154  	http2cipher_TLS_DHE_PSK_WITH_NULL_SHA             uint16 = 0x002D
   155  	http2cipher_TLS_RSA_PSK_WITH_NULL_SHA             uint16 = 0x002E
   156  	http2cipher_TLS_RSA_WITH_AES_128_CBC_SHA          uint16 = 0x002F
   157  	http2cipher_TLS_DH_DSS_WITH_AES_128_CBC_SHA       uint16 = 0x0030
   158  	http2cipher_TLS_DH_RSA_WITH_AES_128_CBC_SHA       uint16 = 0x0031
   159  	http2cipher_TLS_DHE_DSS_WITH_AES_128_CBC_SHA      uint16 = 0x0032
   160  	http2cipher_TLS_DHE_RSA_WITH_AES_128_CBC_SHA      uint16 = 0x0033
   161  	http2cipher_TLS_DH_anon_WITH_AES_128_CBC_SHA      uint16 = 0x0034
   162  	http2cipher_TLS_RSA_WITH_AES_256_CBC_SHA          uint16 = 0x0035
   163  	http2cipher_TLS_DH_DSS_WITH_AES_256_CBC_SHA       uint16 = 0x0036
   164  	http2cipher_TLS_DH_RSA_WITH_AES_256_CBC_SHA       uint16 = 0x0037
   165  	http2cipher_TLS_DHE_DSS_WITH_AES_256_CBC_SHA      uint16 = 0x0038
   166  	http2cipher_TLS_DHE_RSA_WITH_AES_256_CBC_SHA      uint16 = 0x0039
   167  	http2cipher_TLS_DH_anon_WITH_AES_256_CBC_SHA      uint16 = 0x003A
   168  	http2cipher_TLS_RSA_WITH_NULL_SHA256              uint16 = 0x003B
   169  	http2cipher_TLS_RSA_WITH_AES_128_CBC_SHA256       uint16 = 0x003C
   170  	http2cipher_TLS_RSA_WITH_AES_256_CBC_SHA256       uint16 = 0x003D
   171  	http2cipher_TLS_DH_DSS_WITH_AES_128_CBC_SHA256    uint16 = 0x003E
   172  	http2cipher_TLS_DH_RSA_WITH_AES_128_CBC_SHA256    uint16 = 0x003F
   173  	http2cipher_TLS_DHE_DSS_WITH_AES_128_CBC_SHA256   uint16 = 0x0040
   174  	http2cipher_TLS_RSA_WITH_CAMELLIA_128_CBC_SHA     uint16 = 0x0041
   175  	http2cipher_TLS_DH_DSS_WITH_CAMELLIA_128_CBC_SHA  uint16 = 0x0042
   176  	http2cipher_TLS_DH_RSA_WITH_CAMELLIA_128_CBC_SHA  uint16 = 0x0043
   177  	http2cipher_TLS_DHE_DSS_WITH_CAMELLIA_128_CBC_SHA uint16 = 0x0044
   178  	http2cipher_TLS_DHE_RSA_WITH_CAMELLIA_128_CBC_SHA uint16 = 0x0045
   179  	http2cipher_TLS_DH_anon_WITH_CAMELLIA_128_CBC_SHA uint16 = 0x0046
   180  	// Reserved uint16 =  0x0047-4F
   181  	// Reserved uint16 =  0x0050-58
   182  	// Reserved uint16 =  0x0059-5C
   183  	// Unassigned uint16 =  0x005D-5F
   184  	// Reserved uint16 =  0x0060-66
   185  	http2cipher_TLS_DHE_RSA_WITH_AES_128_CBC_SHA256 uint16 = 0x0067
   186  	http2cipher_TLS_DH_DSS_WITH_AES_256_CBC_SHA256  uint16 = 0x0068
   187  	http2cipher_TLS_DH_RSA_WITH_AES_256_CBC_SHA256  uint16 = 0x0069
   188  	http2cipher_TLS_DHE_DSS_WITH_AES_256_CBC_SHA256 uint16 = 0x006A
   189  	http2cipher_TLS_DHE_RSA_WITH_AES_256_CBC_SHA256 uint16 = 0x006B
   190  	http2cipher_TLS_DH_anon_WITH_AES_128_CBC_SHA256 uint16 = 0x006C
   191  	http2cipher_TLS_DH_anon_WITH_AES_256_CBC_SHA256 uint16 = 0x006D
   192  	// Unassigned uint16 =  0x006E-83
   193  	http2cipher_TLS_RSA_WITH_CAMELLIA_256_CBC_SHA        uint16 = 0x0084
   194  	http2cipher_TLS_DH_DSS_WITH_CAMELLIA_256_CBC_SHA     uint16 = 0x0085
   195  	http2cipher_TLS_DH_RSA_WITH_CAMELLIA_256_CBC_SHA     uint16 = 0x0086
   196  	http2cipher_TLS_DHE_DSS_WITH_CAMELLIA_256_CBC_SHA    uint16 = 0x0087
   197  	http2cipher_TLS_DHE_RSA_WITH_CAMELLIA_256_CBC_SHA    uint16 = 0x0088
   198  	http2cipher_TLS_DH_anon_WITH_CAMELLIA_256_CBC_SHA    uint16 = 0x0089
   199  	http2cipher_TLS_PSK_WITH_RC4_128_SHA                 uint16 = 0x008A
   200  	http2cipher_TLS_PSK_WITH_3DES_EDE_CBC_SHA            uint16 = 0x008B
   201  	http2cipher_TLS_PSK_WITH_AES_128_CBC_SHA             uint16 = 0x008C
   202  	http2cipher_TLS_PSK_WITH_AES_256_CBC_SHA             uint16 = 0x008D
   203  	http2cipher_TLS_DHE_PSK_WITH_RC4_128_SHA             uint16 = 0x008E
   204  	http2cipher_TLS_DHE_PSK_WITH_3DES_EDE_CBC_SHA        uint16 = 0x008F
   205  	http2cipher_TLS_DHE_PSK_WITH_AES_128_CBC_SHA         uint16 = 0x0090
   206  	http2cipher_TLS_DHE_PSK_WITH_AES_256_CBC_SHA         uint16 = 0x0091
   207  	http2cipher_TLS_RSA_PSK_WITH_RC4_128_SHA             uint16 = 0x0092
   208  	http2cipher_TLS_RSA_PSK_WITH_3DES_EDE_CBC_SHA        uint16 = 0x0093
   209  	http2cipher_TLS_RSA_PSK_WITH_AES_128_CBC_SHA         uint16 = 0x0094
   210  	http2cipher_TLS_RSA_PSK_WITH_AES_256_CBC_SHA         uint16 = 0x0095
   211  	http2cipher_TLS_RSA_WITH_SEED_CBC_SHA                uint16 = 0x0096
   212  	http2cipher_TLS_DH_DSS_WITH_SEED_CBC_SHA             uint16 = 0x0097
   213  	http2cipher_TLS_DH_RSA_WITH_SEED_CBC_SHA             uint16 = 0x0098
   214  	http2cipher_TLS_DHE_DSS_WITH_SEED_CBC_SHA            uint16 = 0x0099
   215  	http2cipher_TLS_DHE_RSA_WITH_SEED_CBC_SHA            uint16 = 0x009A
   216  	http2cipher_TLS_DH_anon_WITH_SEED_CBC_SHA            uint16 = 0x009B
   217  	http2cipher_TLS_RSA_WITH_AES_128_GCM_SHA256          uint16 = 0x009C
   218  	http2cipher_TLS_RSA_WITH_AES_256_GCM_SHA384          uint16 = 0x009D
   219  	http2cipher_TLS_DHE_RSA_WITH_AES_128_GCM_SHA256      uint16 = 0x009E
   220  	http2cipher_TLS_DHE_RSA_WITH_AES_256_GCM_SHA384      uint16 = 0x009F
   221  	http2cipher_TLS_DH_RSA_WITH_AES_128_GCM_SHA256       uint16 = 0x00A0
   222  	http2cipher_TLS_DH_RSA_WITH_AES_256_GCM_SHA384       uint16 = 0x00A1
   223  	http2cipher_TLS_DHE_DSS_WITH_AES_128_GCM_SHA256      uint16 = 0x00A2
   224  	http2cipher_TLS_DHE_DSS_WITH_AES_256_GCM_SHA384      uint16 = 0x00A3
   225  	http2cipher_TLS_DH_DSS_WITH_AES_128_GCM_SHA256       uint16 = 0x00A4
   226  	http2cipher_TLS_DH_DSS_WITH_AES_256_GCM_SHA384       uint16 = 0x00A5
   227  	http2cipher_TLS_DH_anon_WITH_AES_128_GCM_SHA256      uint16 = 0x00A6
   228  	http2cipher_TLS_DH_anon_WITH_AES_256_GCM_SHA384      uint16 = 0x00A7
   229  	http2cipher_TLS_PSK_WITH_AES_128_GCM_SHA256          uint16 = 0x00A8
   230  	http2cipher_TLS_PSK_WITH_AES_256_GCM_SHA384          uint16 = 0x00A9
   231  	http2cipher_TLS_DHE_PSK_WITH_AES_128_GCM_SHA256      uint16 = 0x00AA
   232  	http2cipher_TLS_DHE_PSK_WITH_AES_256_GCM_SHA384      uint16 = 0x00AB
   233  	http2cipher_TLS_RSA_PSK_WITH_AES_128_GCM_SHA256      uint16 = 0x00AC
   234  	http2cipher_TLS_RSA_PSK_WITH_AES_256_GCM_SHA384      uint16 = 0x00AD
   235  	http2cipher_TLS_PSK_WITH_AES_128_CBC_SHA256          uint16 = 0x00AE
   236  	http2cipher_TLS_PSK_WITH_AES_256_CBC_SHA384          uint16 = 0x00AF
   237  	http2cipher_TLS_PSK_WITH_NULL_SHA256                 uint16 = 0x00B0
   238  	http2cipher_TLS_PSK_WITH_NULL_SHA384                 uint16 = 0x00B1
   239  	http2cipher_TLS_DHE_PSK_WITH_AES_128_CBC_SHA256      uint16 = 0x00B2
   240  	http2cipher_TLS_DHE_PSK_WITH_AES_256_CBC_SHA384      uint16 = 0x00B3
   241  	http2cipher_TLS_DHE_PSK_WITH_NULL_SHA256             uint16 = 0x00B4
   242  	http2cipher_TLS_DHE_PSK_WITH_NULL_SHA384             uint16 = 0x00B5
   243  	http2cipher_TLS_RSA_PSK_WITH_AES_128_CBC_SHA256      uint16 = 0x00B6
   244  	http2cipher_TLS_RSA_PSK_WITH_AES_256_CBC_SHA384      uint16 = 0x00B7
   245  	http2cipher_TLS_RSA_PSK_WITH_NULL_SHA256             uint16 = 0x00B8
   246  	http2cipher_TLS_RSA_PSK_WITH_NULL_SHA384             uint16 = 0x00B9
   247  	http2cipher_TLS_RSA_WITH_CAMELLIA_128_CBC_SHA256     uint16 = 0x00BA
   248  	http2cipher_TLS_DH_DSS_WITH_CAMELLIA_128_CBC_SHA256  uint16 = 0x00BB
   249  	http2cipher_TLS_DH_RSA_WITH_CAMELLIA_128_CBC_SHA256  uint16 = 0x00BC
   250  	http2cipher_TLS_DHE_DSS_WITH_CAMELLIA_128_CBC_SHA256 uint16 = 0x00BD
   251  	http2cipher_TLS_DHE_RSA_WITH_CAMELLIA_128_CBC_SHA256 uint16 = 0x00BE
   252  	http2cipher_TLS_DH_anon_WITH_CAMELLIA_128_CBC_SHA256 uint16 = 0x00BF
   253  	http2cipher_TLS_RSA_WITH_CAMELLIA_256_CBC_SHA256     uint16 = 0x00C0
   254  	http2cipher_TLS_DH_DSS_WITH_CAMELLIA_256_CBC_SHA256  uint16 = 0x00C1
   255  	http2cipher_TLS_DH_RSA_WITH_CAMELLIA_256_CBC_SHA256  uint16 = 0x00C2
   256  	http2cipher_TLS_DHE_DSS_WITH_CAMELLIA_256_CBC_SHA256 uint16 = 0x00C3
   257  	http2cipher_TLS_DHE_RSA_WITH_CAMELLIA_256_CBC_SHA256 uint16 = 0x00C4
   258  	http2cipher_TLS_DH_anon_WITH_CAMELLIA_256_CBC_SHA256 uint16 = 0x00C5
   259  	// Unassigned uint16 =  0x00C6-FE
   260  	http2cipher_TLS_EMPTY_RENEGOTIATION_INFO_SCSV uint16 = 0x00FF
   261  	// Unassigned uint16 =  0x01-55,*
   262  	http2cipher_TLS_FALLBACK_SCSV uint16 = 0x5600
   263  	// Unassigned                                   uint16 = 0x5601 - 0xC000
   264  	http2cipher_TLS_ECDH_ECDSA_WITH_NULL_SHA                 uint16 = 0xC001
   265  	http2cipher_TLS_ECDH_ECDSA_WITH_RC4_128_SHA              uint16 = 0xC002
   266  	http2cipher_TLS_ECDH_ECDSA_WITH_3DES_EDE_CBC_SHA         uint16 = 0xC003
   267  	http2cipher_TLS_ECDH_ECDSA_WITH_AES_128_CBC_SHA          uint16 = 0xC004
   268  	http2cipher_TLS_ECDH_ECDSA_WITH_AES_256_CBC_SHA          uint16 = 0xC005
   269  	http2cipher_TLS_ECDHE_ECDSA_WITH_NULL_SHA                uint16 = 0xC006
   270  	http2cipher_TLS_ECDHE_ECDSA_WITH_RC4_128_SHA             uint16 = 0xC007
   271  	http2cipher_TLS_ECDHE_ECDSA_WITH_3DES_EDE_CBC_SHA        uint16 = 0xC008
   272  	http2cipher_TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA         uint16 = 0xC009
   273  	http2cipher_TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA         uint16 = 0xC00A
   274  	http2cipher_TLS_ECDH_RSA_WITH_NULL_SHA                   uint16 = 0xC00B
   275  	http2cipher_TLS_ECDH_RSA_WITH_RC4_128_SHA                uint16 = 0xC00C
   276  	http2cipher_TLS_ECDH_RSA_WITH_3DES_EDE_CBC_SHA           uint16 = 0xC00D
   277  	http2cipher_TLS_ECDH_RSA_WITH_AES_128_CBC_SHA            uint16 = 0xC00E
   278  	http2cipher_TLS_ECDH_RSA_WITH_AES_256_CBC_SHA            uint16 = 0xC00F
   279  	http2cipher_TLS_ECDHE_RSA_WITH_NULL_SHA                  uint16 = 0xC010
   280  	http2cipher_TLS_ECDHE_RSA_WITH_RC4_128_SHA               uint16 = 0xC011
   281  	http2cipher_TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA          uint16 = 0xC012
   282  	http2cipher_TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA           uint16 = 0xC013
   283  	http2cipher_TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA           uint16 = 0xC014
   284  	http2cipher_TLS_ECDH_anon_WITH_NULL_SHA                  uint16 = 0xC015
   285  	http2cipher_TLS_ECDH_anon_WITH_RC4_128_SHA               uint16 = 0xC016
   286  	http2cipher_TLS_ECDH_anon_WITH_3DES_EDE_CBC_SHA          uint16 = 0xC017
   287  	http2cipher_TLS_ECDH_anon_WITH_AES_128_CBC_SHA           uint16 = 0xC018
   288  	http2cipher_TLS_ECDH_anon_WITH_AES_256_CBC_SHA           uint16 = 0xC019
   289  	http2cipher_TLS_SRP_SHA_WITH_3DES_EDE_CBC_SHA            uint16 = 0xC01A
   290  	http2cipher_TLS_SRP_SHA_RSA_WITH_3DES_EDE_CBC_SHA        uint16 = 0xC01B
   291  	http2cipher_TLS_SRP_SHA_DSS_WITH_3DES_EDE_CBC_SHA        uint16 = 0xC01C
   292  	http2cipher_TLS_SRP_SHA_WITH_AES_128_CBC_SHA             uint16 = 0xC01D
   293  	http2cipher_TLS_SRP_SHA_RSA_WITH_AES_128_CBC_SHA         uint16 = 0xC01E
   294  	http2cipher_TLS_SRP_SHA_DSS_WITH_AES_128_CBC_SHA         uint16 = 0xC01F
   295  	http2cipher_TLS_SRP_SHA_WITH_AES_256_CBC_SHA             uint16 = 0xC020
   296  	http2cipher_TLS_SRP_SHA_RSA_WITH_AES_256_CBC_SHA         uint16 = 0xC021
   297  	http2cipher_TLS_SRP_SHA_DSS_WITH_AES_256_CBC_SHA         uint16 = 0xC022
   298  	http2cipher_TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256      uint16 = 0xC023
   299  	http2cipher_TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA384      uint16 = 0xC024
   300  	http2cipher_TLS_ECDH_ECDSA_WITH_AES_128_CBC_SHA256       uint16 = 0xC025
   301  	http2cipher_TLS_ECDH_ECDSA_WITH_AES_256_CBC_SHA384       uint16 = 0xC026
   302  	http2cipher_TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256        uint16 = 0xC027
   303  	http2cipher_TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384        uint16 = 0xC028
   304  	http2cipher_TLS_ECDH_RSA_WITH_AES_128_CBC_SHA256         uint16 = 0xC029
   305  	http2cipher_TLS_ECDH_RSA_WITH_AES_256_CBC_SHA384         uint16 = 0xC02A
   306  	http2cipher_TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256      uint16 = 0xC02B
   307  	http2cipher_TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384      uint16 = 0xC02C
   308  	http2cipher_TLS_ECDH_ECDSA_WITH_AES_128_GCM_SHA256       uint16 = 0xC02D
   309  	http2cipher_TLS_ECDH_ECDSA_WITH_AES_256_GCM_SHA384       uint16 = 0xC02E
   310  	http2cipher_TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256        uint16 = 0xC02F
   311  	http2cipher_TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384        uint16 = 0xC030
   312  	http2cipher_TLS_ECDH_RSA_WITH_AES_128_GCM_SHA256         uint16 = 0xC031
   313  	http2cipher_TLS_ECDH_RSA_WITH_AES_256_GCM_SHA384         uint16 = 0xC032
   314  	http2cipher_TLS_ECDHE_PSK_WITH_RC4_128_SHA               uint16 = 0xC033
   315  	http2cipher_TLS_ECDHE_PSK_WITH_3DES_EDE_CBC_SHA          uint16 = 0xC034
   316  	http2cipher_TLS_ECDHE_PSK_WITH_AES_128_CBC_SHA           uint16 = 0xC035
   317  	http2cipher_TLS_ECDHE_PSK_WITH_AES_256_CBC_SHA           uint16 = 0xC036
   318  	http2cipher_TLS_ECDHE_PSK_WITH_AES_128_CBC_SHA256        uint16 = 0xC037
   319  	http2cipher_TLS_ECDHE_PSK_WITH_AES_256_CBC_SHA384        uint16 = 0xC038
   320  	http2cipher_TLS_ECDHE_PSK_WITH_NULL_SHA                  uint16 = 0xC039
   321  	http2cipher_TLS_ECDHE_PSK_WITH_NULL_SHA256               uint16 = 0xC03A
   322  	http2cipher_TLS_ECDHE_PSK_WITH_NULL_SHA384               uint16 = 0xC03B
   323  	http2cipher_TLS_RSA_WITH_ARIA_128_CBC_SHA256             uint16 = 0xC03C
   324  	http2cipher_TLS_RSA_WITH_ARIA_256_CBC_SHA384             uint16 = 0xC03D
   325  	http2cipher_TLS_DH_DSS_WITH_ARIA_128_CBC_SHA256          uint16 = 0xC03E
   326  	http2cipher_TLS_DH_DSS_WITH_ARIA_256_CBC_SHA384          uint16 = 0xC03F
   327  	http2cipher_TLS_DH_RSA_WITH_ARIA_128_CBC_SHA256          uint16 = 0xC040
   328  	http2cipher_TLS_DH_RSA_WITH_ARIA_256_CBC_SHA384          uint16 = 0xC041
   329  	http2cipher_TLS_DHE_DSS_WITH_ARIA_128_CBC_SHA256         uint16 = 0xC042
   330  	http2cipher_TLS_DHE_DSS_WITH_ARIA_256_CBC_SHA384         uint16 = 0xC043
   331  	http2cipher_TLS_DHE_RSA_WITH_ARIA_128_CBC_SHA256         uint16 = 0xC044
   332  	http2cipher_TLS_DHE_RSA_WITH_ARIA_256_CBC_SHA384         uint16 = 0xC045
   333  	http2cipher_TLS_DH_anon_WITH_ARIA_128_CBC_SHA256         uint16 = 0xC046
   334  	http2cipher_TLS_DH_anon_WITH_ARIA_256_CBC_SHA384         uint16 = 0xC047
   335  	http2cipher_TLS_ECDHE_ECDSA_WITH_ARIA_128_CBC_SHA256     uint16 = 0xC048
   336  	http2cipher_TLS_ECDHE_ECDSA_WITH_ARIA_256_CBC_SHA384     uint16 = 0xC049
   337  	http2cipher_TLS_ECDH_ECDSA_WITH_ARIA_128_CBC_SHA256      uint16 = 0xC04A
   338  	http2cipher_TLS_ECDH_ECDSA_WITH_ARIA_256_CBC_SHA384      uint16 = 0xC04B
   339  	http2cipher_TLS_ECDHE_RSA_WITH_ARIA_128_CBC_SHA256       uint16 = 0xC04C
   340  	http2cipher_TLS_ECDHE_RSA_WITH_ARIA_256_CBC_SHA384       uint16 = 0xC04D
   341  	http2cipher_TLS_ECDH_RSA_WITH_ARIA_128_CBC_SHA256        uint16 = 0xC04E
   342  	http2cipher_TLS_ECDH_RSA_WITH_ARIA_256_CBC_SHA384        uint16 = 0xC04F
   343  	http2cipher_TLS_RSA_WITH_ARIA_128_GCM_SHA256             uint16 = 0xC050
   344  	http2cipher_TLS_RSA_WITH_ARIA_256_GCM_SHA384             uint16 = 0xC051
   345  	http2cipher_TLS_DHE_RSA_WITH_ARIA_128_GCM_SHA256         uint16 = 0xC052
   346  	http2cipher_TLS_DHE_RSA_WITH_ARIA_256_GCM_SHA384         uint16 = 0xC053
   347  	http2cipher_TLS_DH_RSA_WITH_ARIA_128_GCM_SHA256          uint16 = 0xC054
   348  	http2cipher_TLS_DH_RSA_WITH_ARIA_256_GCM_SHA384          uint16 = 0xC055
   349  	http2cipher_TLS_DHE_DSS_WITH_ARIA_128_GCM_SHA256         uint16 = 0xC056
   350  	http2cipher_TLS_DHE_DSS_WITH_ARIA_256_GCM_SHA384         uint16 = 0xC057
   351  	http2cipher_TLS_DH_DSS_WITH_ARIA_128_GCM_SHA256          uint16 = 0xC058
   352  	http2cipher_TLS_DH_DSS_WITH_ARIA_256_GCM_SHA384          uint16 = 0xC059
   353  	http2cipher_TLS_DH_anon_WITH_ARIA_128_GCM_SHA256         uint16 = 0xC05A
   354  	http2cipher_TLS_DH_anon_WITH_ARIA_256_GCM_SHA384         uint16 = 0xC05B
   355  	http2cipher_TLS_ECDHE_ECDSA_WITH_ARIA_128_GCM_SHA256     uint16 = 0xC05C
   356  	http2cipher_TLS_ECDHE_ECDSA_WITH_ARIA_256_GCM_SHA384     uint16 = 0xC05D
   357  	http2cipher_TLS_ECDH_ECDSA_WITH_ARIA_128_GCM_SHA256      uint16 = 0xC05E
   358  	http2cipher_TLS_ECDH_ECDSA_WITH_ARIA_256_GCM_SHA384      uint16 = 0xC05F
   359  	http2cipher_TLS_ECDHE_RSA_WITH_ARIA_128_GCM_SHA256       uint16 = 0xC060
   360  	http2cipher_TLS_ECDHE_RSA_WITH_ARIA_256_GCM_SHA384       uint16 = 0xC061
   361  	http2cipher_TLS_ECDH_RSA_WITH_ARIA_128_GCM_SHA256        uint16 = 0xC062
   362  	http2cipher_TLS_ECDH_RSA_WITH_ARIA_256_GCM_SHA384        uint16 = 0xC063
   363  	http2cipher_TLS_PSK_WITH_ARIA_128_CBC_SHA256             uint16 = 0xC064
   364  	http2cipher_TLS_PSK_WITH_ARIA_256_CBC_SHA384             uint16 = 0xC065
   365  	http2cipher_TLS_DHE_PSK_WITH_ARIA_128_CBC_SHA256         uint16 = 0xC066
   366  	http2cipher_TLS_DHE_PSK_WITH_ARIA_256_CBC_SHA384         uint16 = 0xC067
   367  	http2cipher_TLS_RSA_PSK_WITH_ARIA_128_CBC_SHA256         uint16 = 0xC068
   368  	http2cipher_TLS_RSA_PSK_WITH_ARIA_256_CBC_SHA384         uint16 = 0xC069
   369  	http2cipher_TLS_PSK_WITH_ARIA_128_GCM_SHA256             uint16 = 0xC06A
   370  	http2cipher_TLS_PSK_WITH_ARIA_256_GCM_SHA384             uint16 = 0xC06B
   371  	http2cipher_TLS_DHE_PSK_WITH_ARIA_128_GCM_SHA256         uint16 = 0xC06C
   372  	http2cipher_TLS_DHE_PSK_WITH_ARIA_256_GCM_SHA384         uint16 = 0xC06D
   373  	http2cipher_TLS_RSA_PSK_WITH_ARIA_128_GCM_SHA256         uint16 = 0xC06E
   374  	http2cipher_TLS_RSA_PSK_WITH_ARIA_256_GCM_SHA384         uint16 = 0xC06F
   375  	http2cipher_TLS_ECDHE_PSK_WITH_ARIA_128_CBC_SHA256       uint16 = 0xC070
   376  	http2cipher_TLS_ECDHE_PSK_WITH_ARIA_256_CBC_SHA384       uint16 = 0xC071
   377  	http2cipher_TLS_ECDHE_ECDSA_WITH_CAMELLIA_128_CBC_SHA256 uint16 = 0xC072
   378  	http2cipher_TLS_ECDHE_ECDSA_WITH_CAMELLIA_256_CBC_SHA384 uint16 = 0xC073
   379  	http2cipher_TLS_ECDH_ECDSA_WITH_CAMELLIA_128_CBC_SHA256  uint16 = 0xC074
   380  	http2cipher_TLS_ECDH_ECDSA_WITH_CAMELLIA_256_CBC_SHA384  uint16 = 0xC075
   381  	http2cipher_TLS_ECDHE_RSA_WITH_CAMELLIA_128_CBC_SHA256   uint16 = 0xC076
   382  	http2cipher_TLS_ECDHE_RSA_WITH_CAMELLIA_256_CBC_SHA384   uint16 = 0xC077
   383  	http2cipher_TLS_ECDH_RSA_WITH_CAMELLIA_128_CBC_SHA256    uint16 = 0xC078
   384  	http2cipher_TLS_ECDH_RSA_WITH_CAMELLIA_256_CBC_SHA384    uint16 = 0xC079
   385  	http2cipher_TLS_RSA_WITH_CAMELLIA_128_GCM_SHA256         uint16 = 0xC07A
   386  	http2cipher_TLS_RSA_WITH_CAMELLIA_256_GCM_SHA384         uint16 = 0xC07B
   387  	http2cipher_TLS_DHE_RSA_WITH_CAMELLIA_128_GCM_SHA256     uint16 = 0xC07C
   388  	http2cipher_TLS_DHE_RSA_WITH_CAMELLIA_256_GCM_SHA384     uint16 = 0xC07D
   389  	http2cipher_TLS_DH_RSA_WITH_CAMELLIA_128_GCM_SHA256      uint16 = 0xC07E
   390  	http2cipher_TLS_DH_RSA_WITH_CAMELLIA_256_GCM_SHA384      uint16 = 0xC07F
   391  	http2cipher_TLS_DHE_DSS_WITH_CAMELLIA_128_GCM_SHA256     uint16 = 0xC080
   392  	http2cipher_TLS_DHE_DSS_WITH_CAMELLIA_256_GCM_SHA384     uint16 = 0xC081
   393  	http2cipher_TLS_DH_DSS_WITH_CAMELLIA_128_GCM_SHA256      uint16 = 0xC082
   394  	http2cipher_TLS_DH_DSS_WITH_CAMELLIA_256_GCM_SHA384      uint16 = 0xC083
   395  	http2cipher_TLS_DH_anon_WITH_CAMELLIA_128_GCM_SHA256     uint16 = 0xC084
   396  	http2cipher_TLS_DH_anon_WITH_CAMELLIA_256_GCM_SHA384     uint16 = 0xC085
   397  	http2cipher_TLS_ECDHE_ECDSA_WITH_CAMELLIA_128_GCM_SHA256 uint16 = 0xC086
   398  	http2cipher_TLS_ECDHE_ECDSA_WITH_CAMELLIA_256_GCM_SHA384 uint16 = 0xC087
   399  	http2cipher_TLS_ECDH_ECDSA_WITH_CAMELLIA_128_GCM_SHA256  uint16 = 0xC088
   400  	http2cipher_TLS_ECDH_ECDSA_WITH_CAMELLIA_256_GCM_SHA384  uint16 = 0xC089
   401  	http2cipher_TLS_ECDHE_RSA_WITH_CAMELLIA_128_GCM_SHA256   uint16 = 0xC08A
   402  	http2cipher_TLS_ECDHE_RSA_WITH_CAMELLIA_256_GCM_SHA384   uint16 = 0xC08B
   403  	http2cipher_TLS_ECDH_RSA_WITH_CAMELLIA_128_GCM_SHA256    uint16 = 0xC08C
   404  	http2cipher_TLS_ECDH_RSA_WITH_CAMELLIA_256_GCM_SHA384    uint16 = 0xC08D
   405  	http2cipher_TLS_PSK_WITH_CAMELLIA_128_GCM_SHA256         uint16 = 0xC08E
   406  	http2cipher_TLS_PSK_WITH_CAMELLIA_256_GCM_SHA384         uint16 = 0xC08F
   407  	http2cipher_TLS_DHE_PSK_WITH_CAMELLIA_128_GCM_SHA256     uint16 = 0xC090
   408  	http2cipher_TLS_DHE_PSK_WITH_CAMELLIA_256_GCM_SHA384     uint16 = 0xC091
   409  	http2cipher_TLS_RSA_PSK_WITH_CAMELLIA_128_GCM_SHA256     uint16 = 0xC092
   410  	http2cipher_TLS_RSA_PSK_WITH_CAMELLIA_256_GCM_SHA384     uint16 = 0xC093
   411  	http2cipher_TLS_PSK_WITH_CAMELLIA_128_CBC_SHA256         uint16 = 0xC094
   412  	http2cipher_TLS_PSK_WITH_CAMELLIA_256_CBC_SHA384         uint16 = 0xC095
   413  	http2cipher_TLS_DHE_PSK_WITH_CAMELLIA_128_CBC_SHA256     uint16 = 0xC096
   414  	http2cipher_TLS_DHE_PSK_WITH_CAMELLIA_256_CBC_SHA384     uint16 = 0xC097
   415  	http2cipher_TLS_RSA_PSK_WITH_CAMELLIA_128_CBC_SHA256     uint16 = 0xC098
   416  	http2cipher_TLS_RSA_PSK_WITH_CAMELLIA_256_CBC_SHA384     uint16 = 0xC099
   417  	http2cipher_TLS_ECDHE_PSK_WITH_CAMELLIA_128_CBC_SHA256   uint16 = 0xC09A
   418  	http2cipher_TLS_ECDHE_PSK_WITH_CAMELLIA_256_CBC_SHA384   uint16 = 0xC09B
   419  	http2cipher_TLS_RSA_WITH_AES_128_CCM                     uint16 = 0xC09C
   420  	http2cipher_TLS_RSA_WITH_AES_256_CCM                     uint16 = 0xC09D
   421  	http2cipher_TLS_DHE_RSA_WITH_AES_128_CCM                 uint16 = 0xC09E
   422  	http2cipher_TLS_DHE_RSA_WITH_AES_256_CCM                 uint16 = 0xC09F
   423  	http2cipher_TLS_RSA_WITH_AES_128_CCM_8                   uint16 = 0xC0A0
   424  	http2cipher_TLS_RSA_WITH_AES_256_CCM_8                   uint16 = 0xC0A1
   425  	http2cipher_TLS_DHE_RSA_WITH_AES_128_CCM_8               uint16 = 0xC0A2
   426  	http2cipher_TLS_DHE_RSA_WITH_AES_256_CCM_8               uint16 = 0xC0A3
   427  	http2cipher_TLS_PSK_WITH_AES_128_CCM                     uint16 = 0xC0A4
   428  	http2cipher_TLS_PSK_WITH_AES_256_CCM                     uint16 = 0xC0A5
   429  	http2cipher_TLS_DHE_PSK_WITH_AES_128_CCM                 uint16 = 0xC0A6
   430  	http2cipher_TLS_DHE_PSK_WITH_AES_256_CCM                 uint16 = 0xC0A7
   431  	http2cipher_TLS_PSK_WITH_AES_128_CCM_8                   uint16 = 0xC0A8
   432  	http2cipher_TLS_PSK_WITH_AES_256_CCM_8                   uint16 = 0xC0A9
   433  	http2cipher_TLS_PSK_DHE_WITH_AES_128_CCM_8               uint16 = 0xC0AA
   434  	http2cipher_TLS_PSK_DHE_WITH_AES_256_CCM_8               uint16 = 0xC0AB
   435  	http2cipher_TLS_ECDHE_ECDSA_WITH_AES_128_CCM             uint16 = 0xC0AC
   436  	http2cipher_TLS_ECDHE_ECDSA_WITH_AES_256_CCM             uint16 = 0xC0AD
   437  	http2cipher_TLS_ECDHE_ECDSA_WITH_AES_128_CCM_8           uint16 = 0xC0AE
   438  	http2cipher_TLS_ECDHE_ECDSA_WITH_AES_256_CCM_8           uint16 = 0xC0AF
   439  	// Unassigned uint16 =  0xC0B0-FF
   440  	// Unassigned uint16 =  0xC1-CB,*
   441  	// Unassigned uint16 =  0xCC00-A7
   442  	http2cipher_TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256   uint16 = 0xCCA8
   443  	http2cipher_TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256 uint16 = 0xCCA9
   444  	http2cipher_TLS_DHE_RSA_WITH_CHACHA20_POLY1305_SHA256     uint16 = 0xCCAA
   445  	http2cipher_TLS_PSK_WITH_CHACHA20_POLY1305_SHA256         uint16 = 0xCCAB
   446  	http2cipher_TLS_ECDHE_PSK_WITH_CHACHA20_POLY1305_SHA256   uint16 = 0xCCAC
   447  	http2cipher_TLS_DHE_PSK_WITH_CHACHA20_POLY1305_SHA256     uint16 = 0xCCAD
   448  	http2cipher_TLS_RSA_PSK_WITH_CHACHA20_POLY1305_SHA256     uint16 = 0xCCAE
   449  )
   450  
   451  // isBadCipher reports whether the cipher is blacklisted by the HTTP/2 spec.
   452  // References:
   453  // https://tools.ietf.org/html/rfc7540#appendix-A
   454  // Reject cipher suites from Appendix A.
   455  // "This list includes those cipher suites that do not
   456  // offer an ephemeral key exchange and those that are
   457  // based on the TLS null, stream or block cipher type"
   458  func http2isBadCipher(cipher uint16) bool {
   459  	switch cipher {
   460  	case http2cipher_TLS_NULL_WITH_NULL_NULL,
   461  		http2cipher_TLS_RSA_WITH_NULL_MD5,
   462  		http2cipher_TLS_RSA_WITH_NULL_SHA,
   463  		http2cipher_TLS_RSA_EXPORT_WITH_RC4_40_MD5,
   464  		http2cipher_TLS_RSA_WITH_RC4_128_MD5,
   465  		http2cipher_TLS_RSA_WITH_RC4_128_SHA,
   466  		http2cipher_TLS_RSA_EXPORT_WITH_RC2_CBC_40_MD5,
   467  		http2cipher_TLS_RSA_WITH_IDEA_CBC_SHA,
   468  		http2cipher_TLS_RSA_EXPORT_WITH_DES40_CBC_SHA,
   469  		http2cipher_TLS_RSA_WITH_DES_CBC_SHA,
   470  		http2cipher_TLS_RSA_WITH_3DES_EDE_CBC_SHA,
   471  		http2cipher_TLS_DH_DSS_EXPORT_WITH_DES40_CBC_SHA,
   472  		http2cipher_TLS_DH_DSS_WITH_DES_CBC_SHA,
   473  		http2cipher_TLS_DH_DSS_WITH_3DES_EDE_CBC_SHA,
   474  		http2cipher_TLS_DH_RSA_EXPORT_WITH_DES40_CBC_SHA,
   475  		http2cipher_TLS_DH_RSA_WITH_DES_CBC_SHA,
   476  		http2cipher_TLS_DH_RSA_WITH_3DES_EDE_CBC_SHA,
   477  		http2cipher_TLS_DHE_DSS_EXPORT_WITH_DES40_CBC_SHA,
   478  		http2cipher_TLS_DHE_DSS_WITH_DES_CBC_SHA,
   479  		http2cipher_TLS_DHE_DSS_WITH_3DES_EDE_CBC_SHA,
   480  		http2cipher_TLS_DHE_RSA_EXPORT_WITH_DES40_CBC_SHA,
   481  		http2cipher_TLS_DHE_RSA_WITH_DES_CBC_SHA,
   482  		http2cipher_TLS_DHE_RSA_WITH_3DES_EDE_CBC_SHA,
   483  		http2cipher_TLS_DH_anon_EXPORT_WITH_RC4_40_MD5,
   484  		http2cipher_TLS_DH_anon_WITH_RC4_128_MD5,
   485  		http2cipher_TLS_DH_anon_EXPORT_WITH_DES40_CBC_SHA,
   486  		http2cipher_TLS_DH_anon_WITH_DES_CBC_SHA,
   487  		http2cipher_TLS_DH_anon_WITH_3DES_EDE_CBC_SHA,
   488  		http2cipher_TLS_KRB5_WITH_DES_CBC_SHA,
   489  		http2cipher_TLS_KRB5_WITH_3DES_EDE_CBC_SHA,
   490  		http2cipher_TLS_KRB5_WITH_RC4_128_SHA,
   491  		http2cipher_TLS_KRB5_WITH_IDEA_CBC_SHA,
   492  		http2cipher_TLS_KRB5_WITH_DES_CBC_MD5,
   493  		http2cipher_TLS_KRB5_WITH_3DES_EDE_CBC_MD5,
   494  		http2cipher_TLS_KRB5_WITH_RC4_128_MD5,
   495  		http2cipher_TLS_KRB5_WITH_IDEA_CBC_MD5,
   496  		http2cipher_TLS_KRB5_EXPORT_WITH_DES_CBC_40_SHA,
   497  		http2cipher_TLS_KRB5_EXPORT_WITH_RC2_CBC_40_SHA,
   498  		http2cipher_TLS_KRB5_EXPORT_WITH_RC4_40_SHA,
   499  		http2cipher_TLS_KRB5_EXPORT_WITH_DES_CBC_40_MD5,
   500  		http2cipher_TLS_KRB5_EXPORT_WITH_RC2_CBC_40_MD5,
   501  		http2cipher_TLS_KRB5_EXPORT_WITH_RC4_40_MD5,
   502  		http2cipher_TLS_PSK_WITH_NULL_SHA,
   503  		http2cipher_TLS_DHE_PSK_WITH_NULL_SHA,
   504  		http2cipher_TLS_RSA_PSK_WITH_NULL_SHA,
   505  		http2cipher_TLS_RSA_WITH_AES_128_CBC_SHA,
   506  		http2cipher_TLS_DH_DSS_WITH_AES_128_CBC_SHA,
   507  		http2cipher_TLS_DH_RSA_WITH_AES_128_CBC_SHA,
   508  		http2cipher_TLS_DHE_DSS_WITH_AES_128_CBC_SHA,
   509  		http2cipher_TLS_DHE_RSA_WITH_AES_128_CBC_SHA,
   510  		http2cipher_TLS_DH_anon_WITH_AES_128_CBC_SHA,
   511  		http2cipher_TLS_RSA_WITH_AES_256_CBC_SHA,
   512  		http2cipher_TLS_DH_DSS_WITH_AES_256_CBC_SHA,
   513  		http2cipher_TLS_DH_RSA_WITH_AES_256_CBC_SHA,
   514  		http2cipher_TLS_DHE_DSS_WITH_AES_256_CBC_SHA,
   515  		http2cipher_TLS_DHE_RSA_WITH_AES_256_CBC_SHA,
   516  		http2cipher_TLS_DH_anon_WITH_AES_256_CBC_SHA,
   517  		http2cipher_TLS_RSA_WITH_NULL_SHA256,
   518  		http2cipher_TLS_RSA_WITH_AES_128_CBC_SHA256,
   519  		http2cipher_TLS_RSA_WITH_AES_256_CBC_SHA256,
   520  		http2cipher_TLS_DH_DSS_WITH_AES_128_CBC_SHA256,
   521  		http2cipher_TLS_DH_RSA_WITH_AES_128_CBC_SHA256,
   522  		http2cipher_TLS_DHE_DSS_WITH_AES_128_CBC_SHA256,
   523  		http2cipher_TLS_RSA_WITH_CAMELLIA_128_CBC_SHA,
   524  		http2cipher_TLS_DH_DSS_WITH_CAMELLIA_128_CBC_SHA,
   525  		http2cipher_TLS_DH_RSA_WITH_CAMELLIA_128_CBC_SHA,
   526  		http2cipher_TLS_DHE_DSS_WITH_CAMELLIA_128_CBC_SHA,
   527  		http2cipher_TLS_DHE_RSA_WITH_CAMELLIA_128_CBC_SHA,
   528  		http2cipher_TLS_DH_anon_WITH_CAMELLIA_128_CBC_SHA,
   529  		http2cipher_TLS_DHE_RSA_WITH_AES_128_CBC_SHA256,
   530  		http2cipher_TLS_DH_DSS_WITH_AES_256_CBC_SHA256,
   531  		http2cipher_TLS_DH_RSA_WITH_AES_256_CBC_SHA256,
   532  		http2cipher_TLS_DHE_DSS_WITH_AES_256_CBC_SHA256,
   533  		http2cipher_TLS_DHE_RSA_WITH_AES_256_CBC_SHA256,
   534  		http2cipher_TLS_DH_anon_WITH_AES_128_CBC_SHA256,
   535  		http2cipher_TLS_DH_anon_WITH_AES_256_CBC_SHA256,
   536  		http2cipher_TLS_RSA_WITH_CAMELLIA_256_CBC_SHA,
   537  		http2cipher_TLS_DH_DSS_WITH_CAMELLIA_256_CBC_SHA,
   538  		http2cipher_TLS_DH_RSA_WITH_CAMELLIA_256_CBC_SHA,
   539  		http2cipher_TLS_DHE_DSS_WITH_CAMELLIA_256_CBC_SHA,
   540  		http2cipher_TLS_DHE_RSA_WITH_CAMELLIA_256_CBC_SHA,
   541  		http2cipher_TLS_DH_anon_WITH_CAMELLIA_256_CBC_SHA,
   542  		http2cipher_TLS_PSK_WITH_RC4_128_SHA,
   543  		http2cipher_TLS_PSK_WITH_3DES_EDE_CBC_SHA,
   544  		http2cipher_TLS_PSK_WITH_AES_128_CBC_SHA,
   545  		http2cipher_TLS_PSK_WITH_AES_256_CBC_SHA,
   546  		http2cipher_TLS_DHE_PSK_WITH_RC4_128_SHA,
   547  		http2cipher_TLS_DHE_PSK_WITH_3DES_EDE_CBC_SHA,
   548  		http2cipher_TLS_DHE_PSK_WITH_AES_128_CBC_SHA,
   549  		http2cipher_TLS_DHE_PSK_WITH_AES_256_CBC_SHA,
   550  		http2cipher_TLS_RSA_PSK_WITH_RC4_128_SHA,
   551  		http2cipher_TLS_RSA_PSK_WITH_3DES_EDE_CBC_SHA,
   552  		http2cipher_TLS_RSA_PSK_WITH_AES_128_CBC_SHA,
   553  		http2cipher_TLS_RSA_PSK_WITH_AES_256_CBC_SHA,
   554  		http2cipher_TLS_RSA_WITH_SEED_CBC_SHA,
   555  		http2cipher_TLS_DH_DSS_WITH_SEED_CBC_SHA,
   556  		http2cipher_TLS_DH_RSA_WITH_SEED_CBC_SHA,
   557  		http2cipher_TLS_DHE_DSS_WITH_SEED_CBC_SHA,
   558  		http2cipher_TLS_DHE_RSA_WITH_SEED_CBC_SHA,
   559  		http2cipher_TLS_DH_anon_WITH_SEED_CBC_SHA,
   560  		http2cipher_TLS_RSA_WITH_AES_128_GCM_SHA256,
   561  		http2cipher_TLS_RSA_WITH_AES_256_GCM_SHA384,
   562  		http2cipher_TLS_DH_RSA_WITH_AES_128_GCM_SHA256,
   563  		http2cipher_TLS_DH_RSA_WITH_AES_256_GCM_SHA384,
   564  		http2cipher_TLS_DH_DSS_WITH_AES_128_GCM_SHA256,
   565  		http2cipher_TLS_DH_DSS_WITH_AES_256_GCM_SHA384,
   566  		http2cipher_TLS_DH_anon_WITH_AES_128_GCM_SHA256,
   567  		http2cipher_TLS_DH_anon_WITH_AES_256_GCM_SHA384,
   568  		http2cipher_TLS_PSK_WITH_AES_128_GCM_SHA256,
   569  		http2cipher_TLS_PSK_WITH_AES_256_GCM_SHA384,
   570  		http2cipher_TLS_RSA_PSK_WITH_AES_128_GCM_SHA256,
   571  		http2cipher_TLS_RSA_PSK_WITH_AES_256_GCM_SHA384,
   572  		http2cipher_TLS_PSK_WITH_AES_128_CBC_SHA256,
   573  		http2cipher_TLS_PSK_WITH_AES_256_CBC_SHA384,
   574  		http2cipher_TLS_PSK_WITH_NULL_SHA256,
   575  		http2cipher_TLS_PSK_WITH_NULL_SHA384,
   576  		http2cipher_TLS_DHE_PSK_WITH_AES_128_CBC_SHA256,
   577  		http2cipher_TLS_DHE_PSK_WITH_AES_256_CBC_SHA384,
   578  		http2cipher_TLS_DHE_PSK_WITH_NULL_SHA256,
   579  		http2cipher_TLS_DHE_PSK_WITH_NULL_SHA384,
   580  		http2cipher_TLS_RSA_PSK_WITH_AES_128_CBC_SHA256,
   581  		http2cipher_TLS_RSA_PSK_WITH_AES_256_CBC_SHA384,
   582  		http2cipher_TLS_RSA_PSK_WITH_NULL_SHA256,
   583  		http2cipher_TLS_RSA_PSK_WITH_NULL_SHA384,
   584  		http2cipher_TLS_RSA_WITH_CAMELLIA_128_CBC_SHA256,
   585  		http2cipher_TLS_DH_DSS_WITH_CAMELLIA_128_CBC_SHA256,
   586  		http2cipher_TLS_DH_RSA_WITH_CAMELLIA_128_CBC_SHA256,
   587  		http2cipher_TLS_DHE_DSS_WITH_CAMELLIA_128_CBC_SHA256,
   588  		http2cipher_TLS_DHE_RSA_WITH_CAMELLIA_128_CBC_SHA256,
   589  		http2cipher_TLS_DH_anon_WITH_CAMELLIA_128_CBC_SHA256,
   590  		http2cipher_TLS_RSA_WITH_CAMELLIA_256_CBC_SHA256,
   591  		http2cipher_TLS_DH_DSS_WITH_CAMELLIA_256_CBC_SHA256,
   592  		http2cipher_TLS_DH_RSA_WITH_CAMELLIA_256_CBC_SHA256,
   593  		http2cipher_TLS_DHE_DSS_WITH_CAMELLIA_256_CBC_SHA256,
   594  		http2cipher_TLS_DHE_RSA_WITH_CAMELLIA_256_CBC_SHA256,
   595  		http2cipher_TLS_DH_anon_WITH_CAMELLIA_256_CBC_SHA256,
   596  		http2cipher_TLS_EMPTY_RENEGOTIATION_INFO_SCSV,
   597  		http2cipher_TLS_ECDH_ECDSA_WITH_NULL_SHA,
   598  		http2cipher_TLS_ECDH_ECDSA_WITH_RC4_128_SHA,
   599  		http2cipher_TLS_ECDH_ECDSA_WITH_3DES_EDE_CBC_SHA,
   600  		http2cipher_TLS_ECDH_ECDSA_WITH_AES_128_CBC_SHA,
   601  		http2cipher_TLS_ECDH_ECDSA_WITH_AES_256_CBC_SHA,
   602  		http2cipher_TLS_ECDHE_ECDSA_WITH_NULL_SHA,
   603  		http2cipher_TLS_ECDHE_ECDSA_WITH_RC4_128_SHA,
   604  		http2cipher_TLS_ECDHE_ECDSA_WITH_3DES_EDE_CBC_SHA,
   605  		http2cipher_TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA,
   606  		http2cipher_TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA,
   607  		http2cipher_TLS_ECDH_RSA_WITH_NULL_SHA,
   608  		http2cipher_TLS_ECDH_RSA_WITH_RC4_128_SHA,
   609  		http2cipher_TLS_ECDH_RSA_WITH_3DES_EDE_CBC_SHA,
   610  		http2cipher_TLS_ECDH_RSA_WITH_AES_128_CBC_SHA,
   611  		http2cipher_TLS_ECDH_RSA_WITH_AES_256_CBC_SHA,
   612  		http2cipher_TLS_ECDHE_RSA_WITH_NULL_SHA,
   613  		http2cipher_TLS_ECDHE_RSA_WITH_RC4_128_SHA,
   614  		http2cipher_TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA,
   615  		http2cipher_TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA,
   616  		http2cipher_TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA,
   617  		http2cipher_TLS_ECDH_anon_WITH_NULL_SHA,
   618  		http2cipher_TLS_ECDH_anon_WITH_RC4_128_SHA,
   619  		http2cipher_TLS_ECDH_anon_WITH_3DES_EDE_CBC_SHA,
   620  		http2cipher_TLS_ECDH_anon_WITH_AES_128_CBC_SHA,
   621  		http2cipher_TLS_ECDH_anon_WITH_AES_256_CBC_SHA,
   622  		http2cipher_TLS_SRP_SHA_WITH_3DES_EDE_CBC_SHA,
   623  		http2cipher_TLS_SRP_SHA_RSA_WITH_3DES_EDE_CBC_SHA,
   624  		http2cipher_TLS_SRP_SHA_DSS_WITH_3DES_EDE_CBC_SHA,
   625  		http2cipher_TLS_SRP_SHA_WITH_AES_128_CBC_SHA,
   626  		http2cipher_TLS_SRP_SHA_RSA_WITH_AES_128_CBC_SHA,
   627  		http2cipher_TLS_SRP_SHA_DSS_WITH_AES_128_CBC_SHA,
   628  		http2cipher_TLS_SRP_SHA_WITH_AES_256_CBC_SHA,
   629  		http2cipher_TLS_SRP_SHA_RSA_WITH_AES_256_CBC_SHA,
   630  		http2cipher_TLS_SRP_SHA_DSS_WITH_AES_256_CBC_SHA,
   631  		http2cipher_TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256,
   632  		http2cipher_TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA384,
   633  		http2cipher_TLS_ECDH_ECDSA_WITH_AES_128_CBC_SHA256,
   634  		http2cipher_TLS_ECDH_ECDSA_WITH_AES_256_CBC_SHA384,
   635  		http2cipher_TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256,
   636  		http2cipher_TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384,
   637  		http2cipher_TLS_ECDH_RSA_WITH_AES_128_CBC_SHA256,
   638  		http2cipher_TLS_ECDH_RSA_WITH_AES_256_CBC_SHA384,
   639  		http2cipher_TLS_ECDH_ECDSA_WITH_AES_128_GCM_SHA256,
   640  		http2cipher_TLS_ECDH_ECDSA_WITH_AES_256_GCM_SHA384,
   641  		http2cipher_TLS_ECDH_RSA_WITH_AES_128_GCM_SHA256,
   642  		http2cipher_TLS_ECDH_RSA_WITH_AES_256_GCM_SHA384,
   643  		http2cipher_TLS_ECDHE_PSK_WITH_RC4_128_SHA,
   644  		http2cipher_TLS_ECDHE_PSK_WITH_3DES_EDE_CBC_SHA,
   645  		http2cipher_TLS_ECDHE_PSK_WITH_AES_128_CBC_SHA,
   646  		http2cipher_TLS_ECDHE_PSK_WITH_AES_256_CBC_SHA,
   647  		http2cipher_TLS_ECDHE_PSK_WITH_AES_128_CBC_SHA256,
   648  		http2cipher_TLS_ECDHE_PSK_WITH_AES_256_CBC_SHA384,
   649  		http2cipher_TLS_ECDHE_PSK_WITH_NULL_SHA,
   650  		http2cipher_TLS_ECDHE_PSK_WITH_NULL_SHA256,
   651  		http2cipher_TLS_ECDHE_PSK_WITH_NULL_SHA384,
   652  		http2cipher_TLS_RSA_WITH_ARIA_128_CBC_SHA256,
   653  		http2cipher_TLS_RSA_WITH_ARIA_256_CBC_SHA384,
   654  		http2cipher_TLS_DH_DSS_WITH_ARIA_128_CBC_SHA256,
   655  		http2cipher_TLS_DH_DSS_WITH_ARIA_256_CBC_SHA384,
   656  		http2cipher_TLS_DH_RSA_WITH_ARIA_128_CBC_SHA256,
   657  		http2cipher_TLS_DH_RSA_WITH_ARIA_256_CBC_SHA384,
   658  		http2cipher_TLS_DHE_DSS_WITH_ARIA_128_CBC_SHA256,
   659  		http2cipher_TLS_DHE_DSS_WITH_ARIA_256_CBC_SHA384,
   660  		http2cipher_TLS_DHE_RSA_WITH_ARIA_128_CBC_SHA256,
   661  		http2cipher_TLS_DHE_RSA_WITH_ARIA_256_CBC_SHA384,
   662  		http2cipher_TLS_DH_anon_WITH_ARIA_128_CBC_SHA256,
   663  		http2cipher_TLS_DH_anon_WITH_ARIA_256_CBC_SHA384,
   664  		http2cipher_TLS_ECDHE_ECDSA_WITH_ARIA_128_CBC_SHA256,
   665  		http2cipher_TLS_ECDHE_ECDSA_WITH_ARIA_256_CBC_SHA384,
   666  		http2cipher_TLS_ECDH_ECDSA_WITH_ARIA_128_CBC_SHA256,
   667  		http2cipher_TLS_ECDH_ECDSA_WITH_ARIA_256_CBC_SHA384,
   668  		http2cipher_TLS_ECDHE_RSA_WITH_ARIA_128_CBC_SHA256,
   669  		http2cipher_TLS_ECDHE_RSA_WITH_ARIA_256_CBC_SHA384,
   670  		http2cipher_TLS_ECDH_RSA_WITH_ARIA_128_CBC_SHA256,
   671  		http2cipher_TLS_ECDH_RSA_WITH_ARIA_256_CBC_SHA384,
   672  		http2cipher_TLS_RSA_WITH_ARIA_128_GCM_SHA256,
   673  		http2cipher_TLS_RSA_WITH_ARIA_256_GCM_SHA384,
   674  		http2cipher_TLS_DH_RSA_WITH_ARIA_128_GCM_SHA256,
   675  		http2cipher_TLS_DH_RSA_WITH_ARIA_256_GCM_SHA384,
   676  		http2cipher_TLS_DH_DSS_WITH_ARIA_128_GCM_SHA256,
   677  		http2cipher_TLS_DH_DSS_WITH_ARIA_256_GCM_SHA384,
   678  		http2cipher_TLS_DH_anon_WITH_ARIA_128_GCM_SHA256,
   679  		http2cipher_TLS_DH_anon_WITH_ARIA_256_GCM_SHA384,
   680  		http2cipher_TLS_ECDH_ECDSA_WITH_ARIA_128_GCM_SHA256,
   681  		http2cipher_TLS_ECDH_ECDSA_WITH_ARIA_256_GCM_SHA384,
   682  		http2cipher_TLS_ECDH_RSA_WITH_ARIA_128_GCM_SHA256,
   683  		http2cipher_TLS_ECDH_RSA_WITH_ARIA_256_GCM_SHA384,
   684  		http2cipher_TLS_PSK_WITH_ARIA_128_CBC_SHA256,
   685  		http2cipher_TLS_PSK_WITH_ARIA_256_CBC_SHA384,
   686  		http2cipher_TLS_DHE_PSK_WITH_ARIA_128_CBC_SHA256,
   687  		http2cipher_TLS_DHE_PSK_WITH_ARIA_256_CBC_SHA384,
   688  		http2cipher_TLS_RSA_PSK_WITH_ARIA_128_CBC_SHA256,
   689  		http2cipher_TLS_RSA_PSK_WITH_ARIA_256_CBC_SHA384,
   690  		http2cipher_TLS_PSK_WITH_ARIA_128_GCM_SHA256,
   691  		http2cipher_TLS_PSK_WITH_ARIA_256_GCM_SHA384,
   692  		http2cipher_TLS_RSA_PSK_WITH_ARIA_128_GCM_SHA256,
   693  		http2cipher_TLS_RSA_PSK_WITH_ARIA_256_GCM_SHA384,
   694  		http2cipher_TLS_ECDHE_PSK_WITH_ARIA_128_CBC_SHA256,
   695  		http2cipher_TLS_ECDHE_PSK_WITH_ARIA_256_CBC_SHA384,
   696  		http2cipher_TLS_ECDHE_ECDSA_WITH_CAMELLIA_128_CBC_SHA256,
   697  		http2cipher_TLS_ECDHE_ECDSA_WITH_CAMELLIA_256_CBC_SHA384,
   698  		http2cipher_TLS_ECDH_ECDSA_WITH_CAMELLIA_128_CBC_SHA256,
   699  		http2cipher_TLS_ECDH_ECDSA_WITH_CAMELLIA_256_CBC_SHA384,
   700  		http2cipher_TLS_ECDHE_RSA_WITH_CAMELLIA_128_CBC_SHA256,
   701  		http2cipher_TLS_ECDHE_RSA_WITH_CAMELLIA_256_CBC_SHA384,
   702  		http2cipher_TLS_ECDH_RSA_WITH_CAMELLIA_128_CBC_SHA256,
   703  		http2cipher_TLS_ECDH_RSA_WITH_CAMELLIA_256_CBC_SHA384,
   704  		http2cipher_TLS_RSA_WITH_CAMELLIA_128_GCM_SHA256,
   705  		http2cipher_TLS_RSA_WITH_CAMELLIA_256_GCM_SHA384,
   706  		http2cipher_TLS_DH_RSA_WITH_CAMELLIA_128_GCM_SHA256,
   707  		http2cipher_TLS_DH_RSA_WITH_CAMELLIA_256_GCM_SHA384,
   708  		http2cipher_TLS_DH_DSS_WITH_CAMELLIA_128_GCM_SHA256,
   709  		http2cipher_TLS_DH_DSS_WITH_CAMELLIA_256_GCM_SHA384,
   710  		http2cipher_TLS_DH_anon_WITH_CAMELLIA_128_GCM_SHA256,
   711  		http2cipher_TLS_DH_anon_WITH_CAMELLIA_256_GCM_SHA384,
   712  		http2cipher_TLS_ECDH_ECDSA_WITH_CAMELLIA_128_GCM_SHA256,
   713  		http2cipher_TLS_ECDH_ECDSA_WITH_CAMELLIA_256_GCM_SHA384,
   714  		http2cipher_TLS_ECDH_RSA_WITH_CAMELLIA_128_GCM_SHA256,
   715  		http2cipher_TLS_ECDH_RSA_WITH_CAMELLIA_256_GCM_SHA384,
   716  		http2cipher_TLS_PSK_WITH_CAMELLIA_128_GCM_SHA256,
   717  		http2cipher_TLS_PSK_WITH_CAMELLIA_256_GCM_SHA384,
   718  		http2cipher_TLS_RSA_PSK_WITH_CAMELLIA_128_GCM_SHA256,
   719  		http2cipher_TLS_RSA_PSK_WITH_CAMELLIA_256_GCM_SHA384,
   720  		http2cipher_TLS_PSK_WITH_CAMELLIA_128_CBC_SHA256,
   721  		http2cipher_TLS_PSK_WITH_CAMELLIA_256_CBC_SHA384,
   722  		http2cipher_TLS_DHE_PSK_WITH_CAMELLIA_128_CBC_SHA256,
   723  		http2cipher_TLS_DHE_PSK_WITH_CAMELLIA_256_CBC_SHA384,
   724  		http2cipher_TLS_RSA_PSK_WITH_CAMELLIA_128_CBC_SHA256,
   725  		http2cipher_TLS_RSA_PSK_WITH_CAMELLIA_256_CBC_SHA384,
   726  		http2cipher_TLS_ECDHE_PSK_WITH_CAMELLIA_128_CBC_SHA256,
   727  		http2cipher_TLS_ECDHE_PSK_WITH_CAMELLIA_256_CBC_SHA384,
   728  		http2cipher_TLS_RSA_WITH_AES_128_CCM,
   729  		http2cipher_TLS_RSA_WITH_AES_256_CCM,
   730  		http2cipher_TLS_RSA_WITH_AES_128_CCM_8,
   731  		http2cipher_TLS_RSA_WITH_AES_256_CCM_8,
   732  		http2cipher_TLS_PSK_WITH_AES_128_CCM,
   733  		http2cipher_TLS_PSK_WITH_AES_256_CCM,
   734  		http2cipher_TLS_PSK_WITH_AES_128_CCM_8,
   735  		http2cipher_TLS_PSK_WITH_AES_256_CCM_8:
   736  		return true
   737  	default:
   738  		return false
   739  	}
   740  }
   741  
   742  // ClientConnPool manages a pool of HTTP/2 client connections.
   743  type http2ClientConnPool interface {
   744  	// GetClientConn returns a specific HTTP/2 connection (usually
   745  	// a TLS-TCP connection) to an HTTP/2 server. On success, the
   746  	// returned ClientConn accounts for the upcoming RoundTrip
   747  	// call, so the caller should not omit it. If the caller needs
   748  	// to, ClientConn.RoundTrip can be called with a bogus
   749  	// new(http.Request) to release the stream reservation.
   750  	GetClientConn(req *Request, addr string) (*http2ClientConn, error)
   751  	MarkDead(*http2ClientConn)
   752  }
   753  
   754  // clientConnPoolIdleCloser is the interface implemented by ClientConnPool
   755  // implementations which can close their idle connections.
   756  type http2clientConnPoolIdleCloser interface {
   757  	http2ClientConnPool
   758  	closeIdleConnections()
   759  }
   760  
   761  var (
   762  	_ http2clientConnPoolIdleCloser = (*http2clientConnPool)(nil)
   763  	_ http2clientConnPoolIdleCloser = http2noDialClientConnPool{}
   764  )
   765  
   766  // TODO: use singleflight for dialing and addConnCalls?
   767  type http2clientConnPool struct {
   768  	t *http2Transport
   769  
   770  	mu sync.Mutex // TODO: maybe switch to RWMutex
   771  	// TODO: add support for sharing conns based on cert names
   772  	// (e.g. share conn for googleapis.com and appspot.com)
   773  	conns        map[string][]*http2ClientConn // key is host:port
   774  	dialing      map[string]*http2dialCall     // currently in-flight dials
   775  	keys         map[*http2ClientConn][]string
   776  	addConnCalls map[string]*http2addConnCall // in-flight addConnIfNeeded calls
   777  }
   778  
   779  func (p *http2clientConnPool) GetClientConn(req *Request, addr string) (*http2ClientConn, error) {
   780  	return p.getClientConn(req, addr, http2dialOnMiss)
   781  }
   782  
   783  const (
   784  	http2dialOnMiss   = true
   785  	http2noDialOnMiss = false
   786  )
   787  
   788  func (p *http2clientConnPool) getClientConn(req *Request, addr string, dialOnMiss bool) (*http2ClientConn, error) {
   789  	// TODO(dneil): Dial a new connection when t.DisableKeepAlives is set?
   790  	if http2isConnectionCloseRequest(req) && dialOnMiss {
   791  		// It gets its own connection.
   792  		http2traceGetConn(req, addr)
   793  		const singleUse = true
   794  		cc, err := p.t.dialClientConn(req.Context(), addr, singleUse)
   795  		if err != nil {
   796  			return nil, err
   797  		}
   798  		return cc, nil
   799  	}
   800  	for {
   801  		p.mu.Lock()
   802  		for _, cc := range p.conns[addr] {
   803  			if cc.ReserveNewRequest() {
   804  				// When a connection is presented to us by the net/http package,
   805  				// the GetConn hook has already been called.
   806  				// Don't call it a second time here.
   807  				if !cc.getConnCalled {
   808  					http2traceGetConn(req, addr)
   809  				}
   810  				cc.getConnCalled = false
   811  				p.mu.Unlock()
   812  				return cc, nil
   813  			}
   814  		}
   815  		if !dialOnMiss {
   816  			p.mu.Unlock()
   817  			return nil, http2ErrNoCachedConn
   818  		}
   819  		http2traceGetConn(req, addr)
   820  		call := p.getStartDialLocked(req.Context(), addr)
   821  		p.mu.Unlock()
   822  		<-call.done
   823  		if http2shouldRetryDial(call, req) {
   824  			continue
   825  		}
   826  		cc, err := call.res, call.err
   827  		if err != nil {
   828  			return nil, err
   829  		}
   830  		if cc.ReserveNewRequest() {
   831  			return cc, nil
   832  		}
   833  	}
   834  }
   835  
   836  // dialCall is an in-flight Transport dial call to a host.
   837  type http2dialCall struct {
   838  	_ http2incomparable
   839  	p *http2clientConnPool
   840  	// the context associated with the request
   841  	// that created this dialCall
   842  	ctx  context.Context
   843  	done chan struct{}    // closed when done
   844  	res  *http2ClientConn // valid after done is closed
   845  	err  error            // valid after done is closed
   846  }
   847  
   848  // requires p.mu is held.
   849  func (p *http2clientConnPool) getStartDialLocked(ctx context.Context, addr string) *http2dialCall {
   850  	if call, ok := p.dialing[addr]; ok {
   851  		// A dial is already in-flight. Don't start another.
   852  		return call
   853  	}
   854  	call := &http2dialCall{p: p, done: make(chan struct{}), ctx: ctx}
   855  	if p.dialing == nil {
   856  		p.dialing = make(map[string]*http2dialCall)
   857  	}
   858  	p.dialing[addr] = call
   859  	go call.dial(call.ctx, addr)
   860  	return call
   861  }
   862  
   863  // run in its own goroutine.
   864  func (c *http2dialCall) dial(ctx context.Context, addr string) {
   865  	const singleUse = false // shared conn
   866  	c.res, c.err = c.p.t.dialClientConn(ctx, addr, singleUse)
   867  
   868  	c.p.mu.Lock()
   869  	delete(c.p.dialing, addr)
   870  	if c.err == nil {
   871  		c.p.addConnLocked(addr, c.res)
   872  	}
   873  	c.p.mu.Unlock()
   874  
   875  	close(c.done)
   876  }
   877  
   878  // addConnIfNeeded makes a NewClientConn out of c if a connection for key doesn't
   879  // already exist. It coalesces concurrent calls with the same key.
   880  // This is used by the http1 Transport code when it creates a new connection. Because
   881  // the http1 Transport doesn't de-dup TCP dials to outbound hosts (because it doesn't know
   882  // the protocol), it can get into a situation where it has multiple TLS connections.
   883  // This code decides which ones live or die.
   884  // The return value used is whether c was used.
   885  // c is never closed.
   886  func (p *http2clientConnPool) addConnIfNeeded(key string, t *http2Transport, c *tls.Conn) (used bool, err error) {
   887  	p.mu.Lock()
   888  	for _, cc := range p.conns[key] {
   889  		if cc.CanTakeNewRequest() {
   890  			p.mu.Unlock()
   891  			return false, nil
   892  		}
   893  	}
   894  	call, dup := p.addConnCalls[key]
   895  	if !dup {
   896  		if p.addConnCalls == nil {
   897  			p.addConnCalls = make(map[string]*http2addConnCall)
   898  		}
   899  		call = &http2addConnCall{
   900  			p:    p,
   901  			done: make(chan struct{}),
   902  		}
   903  		p.addConnCalls[key] = call
   904  		go call.run(t, key, c)
   905  	}
   906  	p.mu.Unlock()
   907  
   908  	<-call.done
   909  	if call.err != nil {
   910  		return false, call.err
   911  	}
   912  	return !dup, nil
   913  }
   914  
   915  type http2addConnCall struct {
   916  	_    http2incomparable
   917  	p    *http2clientConnPool
   918  	done chan struct{} // closed when done
   919  	err  error
   920  }
   921  
   922  func (c *http2addConnCall) run(t *http2Transport, key string, tc *tls.Conn) {
   923  	cc, err := t.NewClientConn(tc)
   924  
   925  	p := c.p
   926  	p.mu.Lock()
   927  	if err != nil {
   928  		c.err = err
   929  	} else {
   930  		cc.getConnCalled = true // already called by the net/http package
   931  		p.addConnLocked(key, cc)
   932  	}
   933  	delete(p.addConnCalls, key)
   934  	p.mu.Unlock()
   935  	close(c.done)
   936  }
   937  
   938  // p.mu must be held
   939  func (p *http2clientConnPool) addConnLocked(key string, cc *http2ClientConn) {
   940  	for _, v := range p.conns[key] {
   941  		if v == cc {
   942  			return
   943  		}
   944  	}
   945  	if p.conns == nil {
   946  		p.conns = make(map[string][]*http2ClientConn)
   947  	}
   948  	if p.keys == nil {
   949  		p.keys = make(map[*http2ClientConn][]string)
   950  	}
   951  	p.conns[key] = append(p.conns[key], cc)
   952  	p.keys[cc] = append(p.keys[cc], key)
   953  }
   954  
   955  func (p *http2clientConnPool) MarkDead(cc *http2ClientConn) {
   956  	p.mu.Lock()
   957  	defer p.mu.Unlock()
   958  	for _, key := range p.keys[cc] {
   959  		vv, ok := p.conns[key]
   960  		if !ok {
   961  			continue
   962  		}
   963  		newList := http2filterOutClientConn(vv, cc)
   964  		if len(newList) > 0 {
   965  			p.conns[key] = newList
   966  		} else {
   967  			delete(p.conns, key)
   968  		}
   969  	}
   970  	delete(p.keys, cc)
   971  }
   972  
   973  func (p *http2clientConnPool) closeIdleConnections() {
   974  	p.mu.Lock()
   975  	defer p.mu.Unlock()
   976  	// TODO: don't close a cc if it was just added to the pool
   977  	// milliseconds ago and has never been used. There's currently
   978  	// a small race window with the HTTP/1 Transport's integration
   979  	// where it can add an idle conn just before using it, and
   980  	// somebody else can concurrently call CloseIdleConns and
   981  	// break some caller's RoundTrip.
   982  	for _, vv := range p.conns {
   983  		for _, cc := range vv {
   984  			cc.closeIfIdle()
   985  		}
   986  	}
   987  }
   988  
   989  func http2filterOutClientConn(in []*http2ClientConn, exclude *http2ClientConn) []*http2ClientConn {
   990  	out := in[:0]
   991  	for _, v := range in {
   992  		if v != exclude {
   993  			out = append(out, v)
   994  		}
   995  	}
   996  	// If we filtered it out, zero out the last item to prevent
   997  	// the GC from seeing it.
   998  	if len(in) != len(out) {
   999  		in[len(in)-1] = nil
  1000  	}
  1001  	return out
  1002  }
  1003  
  1004  // noDialClientConnPool is an implementation of http2.ClientConnPool
  1005  // which never dials. We let the HTTP/1.1 client dial and use its TLS
  1006  // connection instead.
  1007  type http2noDialClientConnPool struct{ *http2clientConnPool }
  1008  
  1009  func (p http2noDialClientConnPool) GetClientConn(req *Request, addr string) (*http2ClientConn, error) {
  1010  	return p.getClientConn(req, addr, http2noDialOnMiss)
  1011  }
  1012  
  1013  // shouldRetryDial reports whether the current request should
  1014  // retry dialing after the call finished unsuccessfully, for example
  1015  // if the dial was canceled because of a context cancellation or
  1016  // deadline expiry.
  1017  func http2shouldRetryDial(call *http2dialCall, req *Request) bool {
  1018  	if call.err == nil {
  1019  		// No error, no need to retry
  1020  		return false
  1021  	}
  1022  	if call.ctx == req.Context() {
  1023  		// If the call has the same context as the request, the dial
  1024  		// should not be retried, since any cancellation will have come
  1025  		// from this request.
  1026  		return false
  1027  	}
  1028  	if !errors.Is(call.err, context.Canceled) && !errors.Is(call.err, context.DeadlineExceeded) {
  1029  		// If the call error is not because of a context cancellation or a deadline expiry,
  1030  		// the dial should not be retried.
  1031  		return false
  1032  	}
  1033  	// Only retry if the error is a context cancellation error or deadline expiry
  1034  	// and the context associated with the call was canceled or expired.
  1035  	return call.ctx.Err() != nil
  1036  }
  1037  
  1038  // Buffer chunks are allocated from a pool to reduce pressure on GC.
  1039  // The maximum wasted space per dataBuffer is 2x the largest size class,
  1040  // which happens when the dataBuffer has multiple chunks and there is
  1041  // one unread byte in both the first and last chunks. We use a few size
  1042  // classes to minimize overheads for servers that typically receive very
  1043  // small request bodies.
  1044  //
  1045  // TODO: Benchmark to determine if the pools are necessary. The GC may have
  1046  // improved enough that we can instead allocate chunks like this:
  1047  // make([]byte, max(16<<10, expectedBytesRemaining))
  1048  var http2dataChunkPools = [...]sync.Pool{
  1049  	{New: func() interface{} { return new([1 << 10]byte) }},
  1050  	{New: func() interface{} { return new([2 << 10]byte) }},
  1051  	{New: func() interface{} { return new([4 << 10]byte) }},
  1052  	{New: func() interface{} { return new([8 << 10]byte) }},
  1053  	{New: func() interface{} { return new([16 << 10]byte) }},
  1054  }
  1055  
  1056  func http2getDataBufferChunk(size int64) []byte {
  1057  	switch {
  1058  	case size <= 1<<10:
  1059  		return http2dataChunkPools[0].Get().(*[1 << 10]byte)[:]
  1060  	case size <= 2<<10:
  1061  		return http2dataChunkPools[1].Get().(*[2 << 10]byte)[:]
  1062  	case size <= 4<<10:
  1063  		return http2dataChunkPools[2].Get().(*[4 << 10]byte)[:]
  1064  	case size <= 8<<10:
  1065  		return http2dataChunkPools[3].Get().(*[8 << 10]byte)[:]
  1066  	default:
  1067  		return http2dataChunkPools[4].Get().(*[16 << 10]byte)[:]
  1068  	}
  1069  }
  1070  
  1071  func http2putDataBufferChunk(p []byte) {
  1072  	switch len(p) {
  1073  	case 1 << 10:
  1074  		http2dataChunkPools[0].Put((*[1 << 10]byte)(p))
  1075  	case 2 << 10:
  1076  		http2dataChunkPools[1].Put((*[2 << 10]byte)(p))
  1077  	case 4 << 10:
  1078  		http2dataChunkPools[2].Put((*[4 << 10]byte)(p))
  1079  	case 8 << 10:
  1080  		http2dataChunkPools[3].Put((*[8 << 10]byte)(p))
  1081  	case 16 << 10:
  1082  		http2dataChunkPools[4].Put((*[16 << 10]byte)(p))
  1083  	default:
  1084  		panic(fmt.Sprintf("unexpected buffer len=%v", len(p)))
  1085  	}
  1086  }
  1087  
  1088  // dataBuffer is an io.ReadWriter backed by a list of data chunks.
  1089  // Each dataBuffer is used to read DATA frames on a single stream.
  1090  // The buffer is divided into chunks so the server can limit the
  1091  // total memory used by a single connection without limiting the
  1092  // request body size on any single stream.
  1093  type http2dataBuffer struct {
  1094  	chunks   [][]byte
  1095  	r        int   // next byte to read is chunks[0][r]
  1096  	w        int   // next byte to write is chunks[len(chunks)-1][w]
  1097  	size     int   // total buffered bytes
  1098  	expected int64 // we expect at least this many bytes in future Write calls (ignored if <= 0)
  1099  }
  1100  
  1101  var http2errReadEmpty = errors.New("read from empty dataBuffer")
  1102  
  1103  // Read copies bytes from the buffer into p.
  1104  // It is an error to read when no data is available.
  1105  func (b *http2dataBuffer) Read(p []byte) (int, error) {
  1106  	if b.size == 0 {
  1107  		return 0, http2errReadEmpty
  1108  	}
  1109  	var ntotal int
  1110  	for len(p) > 0 && b.size > 0 {
  1111  		readFrom := b.bytesFromFirstChunk()
  1112  		n := copy(p, readFrom)
  1113  		p = p[n:]
  1114  		ntotal += n
  1115  		b.r += n
  1116  		b.size -= n
  1117  		// If the first chunk has been consumed, advance to the next chunk.
  1118  		if b.r == len(b.chunks[0]) {
  1119  			http2putDataBufferChunk(b.chunks[0])
  1120  			end := len(b.chunks) - 1
  1121  			copy(b.chunks[:end], b.chunks[1:])
  1122  			b.chunks[end] = nil
  1123  			b.chunks = b.chunks[:end]
  1124  			b.r = 0
  1125  		}
  1126  	}
  1127  	return ntotal, nil
  1128  }
  1129  
  1130  func (b *http2dataBuffer) bytesFromFirstChunk() []byte {
  1131  	if len(b.chunks) == 1 {
  1132  		return b.chunks[0][b.r:b.w]
  1133  	}
  1134  	return b.chunks[0][b.r:]
  1135  }
  1136  
  1137  // Len returns the number of bytes of the unread portion of the buffer.
  1138  func (b *http2dataBuffer) Len() int {
  1139  	return b.size
  1140  }
  1141  
  1142  // Write appends p to the buffer.
  1143  func (b *http2dataBuffer) Write(p []byte) (int, error) {
  1144  	ntotal := len(p)
  1145  	for len(p) > 0 {
  1146  		// If the last chunk is empty, allocate a new chunk. Try to allocate
  1147  		// enough to fully copy p plus any additional bytes we expect to
  1148  		// receive. However, this may allocate less than len(p).
  1149  		want := int64(len(p))
  1150  		if b.expected > want {
  1151  			want = b.expected
  1152  		}
  1153  		chunk := b.lastChunkOrAlloc(want)
  1154  		n := copy(chunk[b.w:], p)
  1155  		p = p[n:]
  1156  		b.w += n
  1157  		b.size += n
  1158  		b.expected -= int64(n)
  1159  	}
  1160  	return ntotal, nil
  1161  }
  1162  
  1163  func (b *http2dataBuffer) lastChunkOrAlloc(want int64) []byte {
  1164  	if len(b.chunks) != 0 {
  1165  		last := b.chunks[len(b.chunks)-1]
  1166  		if b.w < len(last) {
  1167  			return last
  1168  		}
  1169  	}
  1170  	chunk := http2getDataBufferChunk(want)
  1171  	b.chunks = append(b.chunks, chunk)
  1172  	b.w = 0
  1173  	return chunk
  1174  }
  1175  
  1176  // An ErrCode is an unsigned 32-bit error code as defined in the HTTP/2 spec.
  1177  type http2ErrCode uint32
  1178  
  1179  const (
  1180  	http2ErrCodeNo                 http2ErrCode = 0x0
  1181  	http2ErrCodeProtocol           http2ErrCode = 0x1
  1182  	http2ErrCodeInternal           http2ErrCode = 0x2
  1183  	http2ErrCodeFlowControl        http2ErrCode = 0x3
  1184  	http2ErrCodeSettingsTimeout    http2ErrCode = 0x4
  1185  	http2ErrCodeStreamClosed       http2ErrCode = 0x5
  1186  	http2ErrCodeFrameSize          http2ErrCode = 0x6
  1187  	http2ErrCodeRefusedStream      http2ErrCode = 0x7
  1188  	http2ErrCodeCancel             http2ErrCode = 0x8
  1189  	http2ErrCodeCompression        http2ErrCode = 0x9
  1190  	http2ErrCodeConnect            http2ErrCode = 0xa
  1191  	http2ErrCodeEnhanceYourCalm    http2ErrCode = 0xb
  1192  	http2ErrCodeInadequateSecurity http2ErrCode = 0xc
  1193  	http2ErrCodeHTTP11Required     http2ErrCode = 0xd
  1194  )
  1195  
  1196  var http2errCodeName = map[http2ErrCode]string{
  1197  	http2ErrCodeNo:                 "NO_ERROR",
  1198  	http2ErrCodeProtocol:           "PROTOCOL_ERROR",
  1199  	http2ErrCodeInternal:           "INTERNAL_ERROR",
  1200  	http2ErrCodeFlowControl:        "FLOW_CONTROL_ERROR",
  1201  	http2ErrCodeSettingsTimeout:    "SETTINGS_TIMEOUT",
  1202  	http2ErrCodeStreamClosed:       "STREAM_CLOSED",
  1203  	http2ErrCodeFrameSize:          "FRAME_SIZE_ERROR",
  1204  	http2ErrCodeRefusedStream:      "REFUSED_STREAM",
  1205  	http2ErrCodeCancel:             "CANCEL",
  1206  	http2ErrCodeCompression:        "COMPRESSION_ERROR",
  1207  	http2ErrCodeConnect:            "CONNECT_ERROR",
  1208  	http2ErrCodeEnhanceYourCalm:    "ENHANCE_YOUR_CALM",
  1209  	http2ErrCodeInadequateSecurity: "INADEQUATE_SECURITY",
  1210  	http2ErrCodeHTTP11Required:     "HTTP_1_1_REQUIRED",
  1211  }
  1212  
  1213  func (e http2ErrCode) String() string {
  1214  	if s, ok := http2errCodeName[e]; ok {
  1215  		return s
  1216  	}
  1217  	return fmt.Sprintf("unknown error code 0x%x", uint32(e))
  1218  }
  1219  
  1220  func (e http2ErrCode) stringToken() string {
  1221  	if s, ok := http2errCodeName[e]; ok {
  1222  		return s
  1223  	}
  1224  	return fmt.Sprintf("ERR_UNKNOWN_%d", uint32(e))
  1225  }
  1226  
  1227  // ConnectionError is an error that results in the termination of the
  1228  // entire connection.
  1229  type http2ConnectionError http2ErrCode
  1230  
  1231  func (e http2ConnectionError) Error() string {
  1232  	return fmt.Sprintf("connection error: %s", http2ErrCode(e))
  1233  }
  1234  
  1235  // StreamError is an error that only affects one stream within an
  1236  // HTTP/2 connection.
  1237  type http2StreamError struct {
  1238  	StreamID uint32
  1239  	Code     http2ErrCode
  1240  	Cause    error // optional additional detail
  1241  }
  1242  
  1243  // errFromPeer is a sentinel error value for StreamError.Cause to
  1244  // indicate that the StreamError was sent from the peer over the wire
  1245  // and wasn't locally generated in the Transport.
  1246  var http2errFromPeer = errors.New("received from peer")
  1247  
  1248  func http2streamError(id uint32, code http2ErrCode) http2StreamError {
  1249  	return http2StreamError{StreamID: id, Code: code}
  1250  }
  1251  
  1252  func (e http2StreamError) Error() string {
  1253  	if e.Cause != nil {
  1254  		return fmt.Sprintf("stream error: stream ID %d; %v; %v", e.StreamID, e.Code, e.Cause)
  1255  	}
  1256  	return fmt.Sprintf("stream error: stream ID %d; %v", e.StreamID, e.Code)
  1257  }
  1258  
  1259  // 6.9.1 The Flow Control Window
  1260  // "If a sender receives a WINDOW_UPDATE that causes a flow control
  1261  // window to exceed this maximum it MUST terminate either the stream
  1262  // or the connection, as appropriate. For streams, [...]; for the
  1263  // connection, a GOAWAY frame with a FLOW_CONTROL_ERROR code."
  1264  type http2goAwayFlowError struct{}
  1265  
  1266  func (http2goAwayFlowError) Error() string { return "connection exceeded flow control window size" }
  1267  
  1268  // connError represents an HTTP/2 ConnectionError error code, along
  1269  // with a string (for debugging) explaining why.
  1270  //
  1271  // Errors of this type are only returned by the frame parser functions
  1272  // and converted into ConnectionError(Code), after stashing away
  1273  // the Reason into the Framer's errDetail field, accessible via
  1274  // the (*Framer).ErrorDetail method.
  1275  type http2connError struct {
  1276  	Code   http2ErrCode // the ConnectionError error code
  1277  	Reason string       // additional reason
  1278  }
  1279  
  1280  func (e http2connError) Error() string {
  1281  	return fmt.Sprintf("http2: connection error: %v: %v", e.Code, e.Reason)
  1282  }
  1283  
  1284  type http2pseudoHeaderError string
  1285  
  1286  func (e http2pseudoHeaderError) Error() string {
  1287  	return fmt.Sprintf("invalid pseudo-header %q", string(e))
  1288  }
  1289  
  1290  type http2duplicatePseudoHeaderError string
  1291  
  1292  func (e http2duplicatePseudoHeaderError) Error() string {
  1293  	return fmt.Sprintf("duplicate pseudo-header %q", string(e))
  1294  }
  1295  
  1296  type http2headerFieldNameError string
  1297  
  1298  func (e http2headerFieldNameError) Error() string {
  1299  	return fmt.Sprintf("invalid header field name %q", string(e))
  1300  }
  1301  
  1302  type http2headerFieldValueError string
  1303  
  1304  func (e http2headerFieldValueError) Error() string {
  1305  	return fmt.Sprintf("invalid header field value for %q", string(e))
  1306  }
  1307  
  1308  var (
  1309  	http2errMixPseudoHeaderTypes = errors.New("mix of request and response pseudo headers")
  1310  	http2errPseudoAfterRegular   = errors.New("pseudo header field after regular")
  1311  )
  1312  
  1313  // inflowMinRefresh is the minimum number of bytes we'll send for a
  1314  // flow control window update.
  1315  const http2inflowMinRefresh = 4 << 10
  1316  
  1317  // inflow accounts for an inbound flow control window.
  1318  // It tracks both the latest window sent to the peer (used for enforcement)
  1319  // and the accumulated unsent window.
  1320  type http2inflow struct {
  1321  	avail  int32
  1322  	unsent int32
  1323  }
  1324  
  1325  // init sets the initial window.
  1326  func (f *http2inflow) init(n int32) {
  1327  	f.avail = n
  1328  }
  1329  
  1330  // add adds n bytes to the window, with a maximum window size of max,
  1331  // indicating that the peer can now send us more data.
  1332  // For example, the user read from a {Request,Response} body and consumed
  1333  // some of the buffered data, so the peer can now send more.
  1334  // It returns the number of bytes to send in a WINDOW_UPDATE frame to the peer.
  1335  // Window updates are accumulated and sent when the unsent capacity
  1336  // is at least inflowMinRefresh or will at least double the peer's available window.
  1337  func (f *http2inflow) add(n int) (connAdd int32) {
  1338  	if n < 0 {
  1339  		panic("negative update")
  1340  	}
  1341  	unsent := int64(f.unsent) + int64(n)
  1342  	// "A sender MUST NOT allow a flow-control window to exceed 2^31-1 octets."
  1343  	// RFC 7540 Section 6.9.1.
  1344  	const maxWindow = 1<<31 - 1
  1345  	if unsent+int64(f.avail) > maxWindow {
  1346  		panic("flow control update exceeds maximum window size")
  1347  	}
  1348  	f.unsent = int32(unsent)
  1349  	if f.unsent < http2inflowMinRefresh && f.unsent < f.avail {
  1350  		// If there aren't at least inflowMinRefresh bytes of window to send,
  1351  		// and this update won't at least double the window, buffer the update for later.
  1352  		return 0
  1353  	}
  1354  	f.avail += f.unsent
  1355  	f.unsent = 0
  1356  	return int32(unsent)
  1357  }
  1358  
  1359  // take attempts to take n bytes from the peer's flow control window.
  1360  // It reports whether the window has available capacity.
  1361  func (f *http2inflow) take(n uint32) bool {
  1362  	if n > uint32(f.avail) {
  1363  		return false
  1364  	}
  1365  	f.avail -= int32(n)
  1366  	return true
  1367  }
  1368  
  1369  // takeInflows attempts to take n bytes from two inflows,
  1370  // typically connection-level and stream-level flows.
  1371  // It reports whether both windows have available capacity.
  1372  func http2takeInflows(f1, f2 *http2inflow, n uint32) bool {
  1373  	if n > uint32(f1.avail) || n > uint32(f2.avail) {
  1374  		return false
  1375  	}
  1376  	f1.avail -= int32(n)
  1377  	f2.avail -= int32(n)
  1378  	return true
  1379  }
  1380  
  1381  // outflow is the outbound flow control window's size.
  1382  type http2outflow struct {
  1383  	_ http2incomparable
  1384  
  1385  	// n is the number of DATA bytes we're allowed to send.
  1386  	// An outflow is kept both on a conn and a per-stream.
  1387  	n int32
  1388  
  1389  	// conn points to the shared connection-level outflow that is
  1390  	// shared by all streams on that conn. It is nil for the outflow
  1391  	// that's on the conn directly.
  1392  	conn *http2outflow
  1393  }
  1394  
  1395  func (f *http2outflow) setConnFlow(cf *http2outflow) { f.conn = cf }
  1396  
  1397  func (f *http2outflow) available() int32 {
  1398  	n := f.n
  1399  	if f.conn != nil && f.conn.n < n {
  1400  		n = f.conn.n
  1401  	}
  1402  	return n
  1403  }
  1404  
  1405  func (f *http2outflow) take(n int32) {
  1406  	if n > f.available() {
  1407  		panic("internal error: took too much")
  1408  	}
  1409  	f.n -= n
  1410  	if f.conn != nil {
  1411  		f.conn.n -= n
  1412  	}
  1413  }
  1414  
  1415  // add adds n bytes (positive or negative) to the flow control window.
  1416  // It returns false if the sum would exceed 2^31-1.
  1417  func (f *http2outflow) add(n int32) bool {
  1418  	sum := f.n + n
  1419  	if (sum > n) == (f.n > 0) {
  1420  		f.n = sum
  1421  		return true
  1422  	}
  1423  	return false
  1424  }
  1425  
  1426  const http2frameHeaderLen = 9
  1427  
  1428  var http2padZeros = make([]byte, 255) // zeros for padding
  1429  
  1430  // A FrameType is a registered frame type as defined in
  1431  // https://httpwg.org/specs/rfc7540.html#rfc.section.11.2
  1432  type http2FrameType uint8
  1433  
  1434  const (
  1435  	http2FrameData         http2FrameType = 0x0
  1436  	http2FrameHeaders      http2FrameType = 0x1
  1437  	http2FramePriority     http2FrameType = 0x2
  1438  	http2FrameRSTStream    http2FrameType = 0x3
  1439  	http2FrameSettings     http2FrameType = 0x4
  1440  	http2FramePushPromise  http2FrameType = 0x5
  1441  	http2FramePing         http2FrameType = 0x6
  1442  	http2FrameGoAway       http2FrameType = 0x7
  1443  	http2FrameWindowUpdate http2FrameType = 0x8
  1444  	http2FrameContinuation http2FrameType = 0x9
  1445  )
  1446  
  1447  var http2frameName = map[http2FrameType]string{
  1448  	http2FrameData:         "DATA",
  1449  	http2FrameHeaders:      "HEADERS",
  1450  	http2FramePriority:     "PRIORITY",
  1451  	http2FrameRSTStream:    "RST_STREAM",
  1452  	http2FrameSettings:     "SETTINGS",
  1453  	http2FramePushPromise:  "PUSH_PROMISE",
  1454  	http2FramePing:         "PING",
  1455  	http2FrameGoAway:       "GOAWAY",
  1456  	http2FrameWindowUpdate: "WINDOW_UPDATE",
  1457  	http2FrameContinuation: "CONTINUATION",
  1458  }
  1459  
  1460  func (t http2FrameType) String() string {
  1461  	if s, ok := http2frameName[t]; ok {
  1462  		return s
  1463  	}
  1464  	return fmt.Sprintf("UNKNOWN_FRAME_TYPE_%d", uint8(t))
  1465  }
  1466  
  1467  // Flags is a bitmask of HTTP/2 flags.
  1468  // The meaning of flags varies depending on the frame type.
  1469  type http2Flags uint8
  1470  
  1471  // Has reports whether f contains all (0 or more) flags in v.
  1472  func (f http2Flags) Has(v http2Flags) bool {
  1473  	return (f & v) == v
  1474  }
  1475  
  1476  // Frame-specific FrameHeader flag bits.
  1477  const (
  1478  	// Data Frame
  1479  	http2FlagDataEndStream http2Flags = 0x1
  1480  	http2FlagDataPadded    http2Flags = 0x8
  1481  
  1482  	// Headers Frame
  1483  	http2FlagHeadersEndStream  http2Flags = 0x1
  1484  	http2FlagHeadersEndHeaders http2Flags = 0x4
  1485  	http2FlagHeadersPadded     http2Flags = 0x8
  1486  	http2FlagHeadersPriority   http2Flags = 0x20
  1487  
  1488  	// Settings Frame
  1489  	http2FlagSettingsAck http2Flags = 0x1
  1490  
  1491  	// Ping Frame
  1492  	http2FlagPingAck http2Flags = 0x1
  1493  
  1494  	// Continuation Frame
  1495  	http2FlagContinuationEndHeaders http2Flags = 0x4
  1496  
  1497  	http2FlagPushPromiseEndHeaders http2Flags = 0x4
  1498  	http2FlagPushPromisePadded     http2Flags = 0x8
  1499  )
  1500  
  1501  var http2flagName = map[http2FrameType]map[http2Flags]string{
  1502  	http2FrameData: {
  1503  		http2FlagDataEndStream: "END_STREAM",
  1504  		http2FlagDataPadded:    "PADDED",
  1505  	},
  1506  	http2FrameHeaders: {
  1507  		http2FlagHeadersEndStream:  "END_STREAM",
  1508  		http2FlagHeadersEndHeaders: "END_HEADERS",
  1509  		http2FlagHeadersPadded:     "PADDED",
  1510  		http2FlagHeadersPriority:   "PRIORITY",
  1511  	},
  1512  	http2FrameSettings: {
  1513  		http2FlagSettingsAck: "ACK",
  1514  	},
  1515  	http2FramePing: {
  1516  		http2FlagPingAck: "ACK",
  1517  	},
  1518  	http2FrameContinuation: {
  1519  		http2FlagContinuationEndHeaders: "END_HEADERS",
  1520  	},
  1521  	http2FramePushPromise: {
  1522  		http2FlagPushPromiseEndHeaders: "END_HEADERS",
  1523  		http2FlagPushPromisePadded:     "PADDED",
  1524  	},
  1525  }
  1526  
  1527  // a frameParser parses a frame given its FrameHeader and payload
  1528  // bytes. The length of payload will always equal fh.Length (which
  1529  // might be 0).
  1530  type http2frameParser func(fc *http2frameCache, fh http2FrameHeader, countError func(string), payload []byte) (http2Frame, error)
  1531  
  1532  var http2frameParsers = map[http2FrameType]http2frameParser{
  1533  	http2FrameData:         http2parseDataFrame,
  1534  	http2FrameHeaders:      http2parseHeadersFrame,
  1535  	http2FramePriority:     http2parsePriorityFrame,
  1536  	http2FrameRSTStream:    http2parseRSTStreamFrame,
  1537  	http2FrameSettings:     http2parseSettingsFrame,
  1538  	http2FramePushPromise:  http2parsePushPromise,
  1539  	http2FramePing:         http2parsePingFrame,
  1540  	http2FrameGoAway:       http2parseGoAwayFrame,
  1541  	http2FrameWindowUpdate: http2parseWindowUpdateFrame,
  1542  	http2FrameContinuation: http2parseContinuationFrame,
  1543  }
  1544  
  1545  func http2typeFrameParser(t http2FrameType) http2frameParser {
  1546  	if f := http2frameParsers[t]; f != nil {
  1547  		return f
  1548  	}
  1549  	return http2parseUnknownFrame
  1550  }
  1551  
  1552  // A FrameHeader is the 9 byte header of all HTTP/2 frames.
  1553  //
  1554  // See https://httpwg.org/specs/rfc7540.html#FrameHeader
  1555  type http2FrameHeader struct {
  1556  	valid bool // caller can access []byte fields in the Frame
  1557  
  1558  	// Type is the 1 byte frame type. There are ten standard frame
  1559  	// types, but extension frame types may be written by WriteRawFrame
  1560  	// and will be returned by ReadFrame (as UnknownFrame).
  1561  	Type http2FrameType
  1562  
  1563  	// Flags are the 1 byte of 8 potential bit flags per frame.
  1564  	// They are specific to the frame type.
  1565  	Flags http2Flags
  1566  
  1567  	// Length is the length of the frame, not including the 9 byte header.
  1568  	// The maximum size is one byte less than 16MB (uint24), but only
  1569  	// frames up to 16KB are allowed without peer agreement.
  1570  	Length uint32
  1571  
  1572  	// StreamID is which stream this frame is for. Certain frames
  1573  	// are not stream-specific, in which case this field is 0.
  1574  	StreamID uint32
  1575  }
  1576  
  1577  // Header returns h. It exists so FrameHeaders can be embedded in other
  1578  // specific frame types and implement the Frame interface.
  1579  func (h http2FrameHeader) Header() http2FrameHeader { return h }
  1580  
  1581  func (h http2FrameHeader) String() string {
  1582  	var buf bytes.Buffer
  1583  	buf.WriteString("[FrameHeader ")
  1584  	h.writeDebug(&buf)
  1585  	buf.WriteByte(']')
  1586  	return buf.String()
  1587  }
  1588  
  1589  func (h http2FrameHeader) writeDebug(buf *bytes.Buffer) {
  1590  	buf.WriteString(h.Type.String())
  1591  	if h.Flags != 0 {
  1592  		buf.WriteString(" flags=")
  1593  		set := 0
  1594  		for i := uint8(0); i < 8; i++ {
  1595  			if h.Flags&(1<<i) == 0 {
  1596  				continue
  1597  			}
  1598  			set++
  1599  			if set > 1 {
  1600  				buf.WriteByte('|')
  1601  			}
  1602  			name := http2flagName[h.Type][http2Flags(1<<i)]
  1603  			if name != "" {
  1604  				buf.WriteString(name)
  1605  			} else {
  1606  				fmt.Fprintf(buf, "0x%x", 1<<i)
  1607  			}
  1608  		}
  1609  	}
  1610  	if h.StreamID != 0 {
  1611  		fmt.Fprintf(buf, " stream=%d", h.StreamID)
  1612  	}
  1613  	fmt.Fprintf(buf, " len=%d", h.Length)
  1614  }
  1615  
  1616  func (h *http2FrameHeader) checkValid() {
  1617  	if !h.valid {
  1618  		panic("Frame accessor called on non-owned Frame")
  1619  	}
  1620  }
  1621  
  1622  func (h *http2FrameHeader) invalidate() { h.valid = false }
  1623  
  1624  // frame header bytes.
  1625  // Used only by ReadFrameHeader.
  1626  var http2fhBytes = sync.Pool{
  1627  	New: func() interface{} {
  1628  		buf := make([]byte, http2frameHeaderLen)
  1629  		return &buf
  1630  	},
  1631  }
  1632  
  1633  // ReadFrameHeader reads 9 bytes from r and returns a FrameHeader.
  1634  // Most users should use Framer.ReadFrame instead.
  1635  func http2ReadFrameHeader(r io.Reader) (http2FrameHeader, error) {
  1636  	bufp := http2fhBytes.Get().(*[]byte)
  1637  	defer http2fhBytes.Put(bufp)
  1638  	return http2readFrameHeader(*bufp, r)
  1639  }
  1640  
  1641  func http2readFrameHeader(buf []byte, r io.Reader) (http2FrameHeader, error) {
  1642  	_, err := io.ReadFull(r, buf[:http2frameHeaderLen])
  1643  	if err != nil {
  1644  		return http2FrameHeader{}, err
  1645  	}
  1646  	return http2FrameHeader{
  1647  		Length:   (uint32(buf[0])<<16 | uint32(buf[1])<<8 | uint32(buf[2])),
  1648  		Type:     http2FrameType(buf[3]),
  1649  		Flags:    http2Flags(buf[4]),
  1650  		StreamID: binary.BigEndian.Uint32(buf[5:]) & (1<<31 - 1),
  1651  		valid:    true,
  1652  	}, nil
  1653  }
  1654  
  1655  // A Frame is the base interface implemented by all frame types.
  1656  // Callers will generally type-assert the specific frame type:
  1657  // *HeadersFrame, *SettingsFrame, *WindowUpdateFrame, etc.
  1658  //
  1659  // Frames are only valid until the next call to Framer.ReadFrame.
  1660  type http2Frame interface {
  1661  	Header() http2FrameHeader
  1662  
  1663  	// invalidate is called by Framer.ReadFrame to make this
  1664  	// frame's buffers as being invalid, since the subsequent
  1665  	// frame will reuse them.
  1666  	invalidate()
  1667  }
  1668  
  1669  // A Framer reads and writes Frames.
  1670  type http2Framer struct {
  1671  	r         io.Reader
  1672  	lastFrame http2Frame
  1673  	errDetail error
  1674  
  1675  	// countError is a non-nil func that's called on a frame parse
  1676  	// error with some unique error path token. It's initialized
  1677  	// from Transport.CountError or Server.CountError.
  1678  	countError func(errToken string)
  1679  
  1680  	// lastHeaderStream is non-zero if the last frame was an
  1681  	// unfinished HEADERS/CONTINUATION.
  1682  	lastHeaderStream uint32
  1683  
  1684  	maxReadSize uint32
  1685  	headerBuf   [http2frameHeaderLen]byte
  1686  
  1687  	// TODO: let getReadBuf be configurable, and use a less memory-pinning
  1688  	// allocator in server.go to minimize memory pinned for many idle conns.
  1689  	// Will probably also need to make frame invalidation have a hook too.
  1690  	getReadBuf func(size uint32) []byte
  1691  	readBuf    []byte // cache for default getReadBuf
  1692  
  1693  	maxWriteSize uint32 // zero means unlimited; TODO: implement
  1694  
  1695  	w    io.Writer
  1696  	wbuf []byte
  1697  
  1698  	// AllowIllegalWrites permits the Framer's Write methods to
  1699  	// write frames that do not conform to the HTTP/2 spec. This
  1700  	// permits using the Framer to test other HTTP/2
  1701  	// implementations' conformance to the spec.
  1702  	// If false, the Write methods will prefer to return an error
  1703  	// rather than comply.
  1704  	AllowIllegalWrites bool
  1705  
  1706  	// AllowIllegalReads permits the Framer's ReadFrame method
  1707  	// to return non-compliant frames or frame orders.
  1708  	// This is for testing and permits using the Framer to test
  1709  	// other HTTP/2 implementations' conformance to the spec.
  1710  	// It is not compatible with ReadMetaHeaders.
  1711  	AllowIllegalReads bool
  1712  
  1713  	// ReadMetaHeaders if non-nil causes ReadFrame to merge
  1714  	// HEADERS and CONTINUATION frames together and return
  1715  	// MetaHeadersFrame instead.
  1716  	ReadMetaHeaders *hpack.Decoder
  1717  
  1718  	// MaxHeaderListSize is the http2 MAX_HEADER_LIST_SIZE.
  1719  	// It's used only if ReadMetaHeaders is set; 0 means a sane default
  1720  	// (currently 16MB)
  1721  	// If the limit is hit, MetaHeadersFrame.Truncated is set true.
  1722  	MaxHeaderListSize uint32
  1723  
  1724  	// TODO: track which type of frame & with which flags was sent
  1725  	// last. Then return an error (unless AllowIllegalWrites) if
  1726  	// we're in the middle of a header block and a
  1727  	// non-Continuation or Continuation on a different stream is
  1728  	// attempted to be written.
  1729  
  1730  	logReads, logWrites bool
  1731  
  1732  	debugFramer       *http2Framer // only use for logging written writes
  1733  	debugFramerBuf    *bytes.Buffer
  1734  	debugReadLoggerf  func(string, ...interface{})
  1735  	debugWriteLoggerf func(string, ...interface{})
  1736  
  1737  	frameCache *http2frameCache // nil if frames aren't reused (default)
  1738  }
  1739  
  1740  func (fr *http2Framer) maxHeaderListSize() uint32 {
  1741  	if fr.MaxHeaderListSize == 0 {
  1742  		return 16 << 20 // sane default, per docs
  1743  	}
  1744  	return fr.MaxHeaderListSize
  1745  }
  1746  
  1747  func (f *http2Framer) startWrite(ftype http2FrameType, flags http2Flags, streamID uint32) {
  1748  	// Write the FrameHeader.
  1749  	f.wbuf = append(f.wbuf[:0],
  1750  		0, // 3 bytes of length, filled in in endWrite
  1751  		0,
  1752  		0,
  1753  		byte(ftype),
  1754  		byte(flags),
  1755  		byte(streamID>>24),
  1756  		byte(streamID>>16),
  1757  		byte(streamID>>8),
  1758  		byte(streamID))
  1759  }
  1760  
  1761  func (f *http2Framer) endWrite() error {
  1762  	// Now that we know the final size, fill in the FrameHeader in
  1763  	// the space previously reserved for it. Abuse append.
  1764  	length := len(f.wbuf) - http2frameHeaderLen
  1765  	if length >= (1 << 24) {
  1766  		return http2ErrFrameTooLarge
  1767  	}
  1768  	_ = append(f.wbuf[:0],
  1769  		byte(length>>16),
  1770  		byte(length>>8),
  1771  		byte(length))
  1772  	if f.logWrites {
  1773  		f.logWrite()
  1774  	}
  1775  
  1776  	n, err := f.w.Write(f.wbuf)
  1777  	if err == nil && n != len(f.wbuf) {
  1778  		err = io.ErrShortWrite
  1779  	}
  1780  	return err
  1781  }
  1782  
  1783  func (f *http2Framer) logWrite() {
  1784  	if f.debugFramer == nil {
  1785  		f.debugFramerBuf = new(bytes.Buffer)
  1786  		f.debugFramer = http2NewFramer(nil, f.debugFramerBuf)
  1787  		f.debugFramer.logReads = false // we log it ourselves, saying "wrote" below
  1788  		// Let us read anything, even if we accidentally wrote it
  1789  		// in the wrong order:
  1790  		f.debugFramer.AllowIllegalReads = true
  1791  	}
  1792  	f.debugFramerBuf.Write(f.wbuf)
  1793  	fr, err := f.debugFramer.ReadFrame()
  1794  	if err != nil {
  1795  		f.debugWriteLoggerf("http2: Framer %p: failed to decode just-written frame", f)
  1796  		return
  1797  	}
  1798  	f.debugWriteLoggerf("http2: Framer %p: wrote %v", f, http2summarizeFrame(fr))
  1799  }
  1800  
  1801  func (f *http2Framer) writeByte(v byte) { f.wbuf = append(f.wbuf, v) }
  1802  
  1803  func (f *http2Framer) writeBytes(v []byte) { f.wbuf = append(f.wbuf, v...) }
  1804  
  1805  func (f *http2Framer) writeUint16(v uint16) { f.wbuf = append(f.wbuf, byte(v>>8), byte(v)) }
  1806  
  1807  func (f *http2Framer) writeUint32(v uint32) {
  1808  	f.wbuf = append(f.wbuf, byte(v>>24), byte(v>>16), byte(v>>8), byte(v))
  1809  }
  1810  
  1811  const (
  1812  	http2minMaxFrameSize = 1 << 14
  1813  	http2maxFrameSize    = 1<<24 - 1
  1814  )
  1815  
  1816  // SetReuseFrames allows the Framer to reuse Frames.
  1817  // If called on a Framer, Frames returned by calls to ReadFrame are only
  1818  // valid until the next call to ReadFrame.
  1819  func (fr *http2Framer) SetReuseFrames() {
  1820  	if fr.frameCache != nil {
  1821  		return
  1822  	}
  1823  	fr.frameCache = &http2frameCache{}
  1824  }
  1825  
  1826  type http2frameCache struct {
  1827  	dataFrame http2DataFrame
  1828  }
  1829  
  1830  func (fc *http2frameCache) getDataFrame() *http2DataFrame {
  1831  	if fc == nil {
  1832  		return &http2DataFrame{}
  1833  	}
  1834  	return &fc.dataFrame
  1835  }
  1836  
  1837  // NewFramer returns a Framer that writes frames to w and reads them from r.
  1838  func http2NewFramer(w io.Writer, r io.Reader) *http2Framer {
  1839  	fr := &http2Framer{
  1840  		w:                 w,
  1841  		r:                 r,
  1842  		countError:        func(string) {},
  1843  		logReads:          http2logFrameReads,
  1844  		logWrites:         http2logFrameWrites,
  1845  		debugReadLoggerf:  log.Printf,
  1846  		debugWriteLoggerf: log.Printf,
  1847  	}
  1848  	fr.getReadBuf = func(size uint32) []byte {
  1849  		if cap(fr.readBuf) >= int(size) {
  1850  			return fr.readBuf[:size]
  1851  		}
  1852  		fr.readBuf = make([]byte, size)
  1853  		return fr.readBuf
  1854  	}
  1855  	fr.SetMaxReadFrameSize(http2maxFrameSize)
  1856  	return fr
  1857  }
  1858  
  1859  // SetMaxReadFrameSize sets the maximum size of a frame
  1860  // that will be read by a subsequent call to ReadFrame.
  1861  // It is the caller's responsibility to advertise this
  1862  // limit with a SETTINGS frame.
  1863  func (fr *http2Framer) SetMaxReadFrameSize(v uint32) {
  1864  	if v > http2maxFrameSize {
  1865  		v = http2maxFrameSize
  1866  	}
  1867  	fr.maxReadSize = v
  1868  }
  1869  
  1870  // ErrorDetail returns a more detailed error of the last error
  1871  // returned by Framer.ReadFrame. For instance, if ReadFrame
  1872  // returns a StreamError with code PROTOCOL_ERROR, ErrorDetail
  1873  // will say exactly what was invalid. ErrorDetail is not guaranteed
  1874  // to return a non-nil value and like the rest of the http2 package,
  1875  // its return value is not protected by an API compatibility promise.
  1876  // ErrorDetail is reset after the next call to ReadFrame.
  1877  func (fr *http2Framer) ErrorDetail() error {
  1878  	return fr.errDetail
  1879  }
  1880  
  1881  // ErrFrameTooLarge is returned from Framer.ReadFrame when the peer
  1882  // sends a frame that is larger than declared with SetMaxReadFrameSize.
  1883  var http2ErrFrameTooLarge = errors.New("http2: frame too large")
  1884  
  1885  // terminalReadFrameError reports whether err is an unrecoverable
  1886  // error from ReadFrame and no other frames should be read.
  1887  func http2terminalReadFrameError(err error) bool {
  1888  	if _, ok := err.(http2StreamError); ok {
  1889  		return false
  1890  	}
  1891  	return err != nil
  1892  }
  1893  
  1894  // ReadFrame reads a single frame. The returned Frame is only valid
  1895  // until the next call to ReadFrame.
  1896  //
  1897  // If the frame is larger than previously set with SetMaxReadFrameSize, the
  1898  // returned error is ErrFrameTooLarge. Other errors may be of type
  1899  // ConnectionError, StreamError, or anything else from the underlying
  1900  // reader.
  1901  //
  1902  // If ReadFrame returns an error and a non-nil Frame, the Frame's StreamID
  1903  // indicates the stream responsible for the error.
  1904  func (fr *http2Framer) ReadFrame() (http2Frame, error) {
  1905  	fr.errDetail = nil
  1906  	if fr.lastFrame != nil {
  1907  		fr.lastFrame.invalidate()
  1908  	}
  1909  	fh, err := http2readFrameHeader(fr.headerBuf[:], fr.r)
  1910  	if err != nil {
  1911  		return nil, err
  1912  	}
  1913  	if fh.Length > fr.maxReadSize {
  1914  		return nil, http2ErrFrameTooLarge
  1915  	}
  1916  	payload := fr.getReadBuf(fh.Length)
  1917  	if _, err := io.ReadFull(fr.r, payload); err != nil {
  1918  		return nil, err
  1919  	}
  1920  	f, err := http2typeFrameParser(fh.Type)(fr.frameCache, fh, fr.countError, payload)
  1921  	if err != nil {
  1922  		if ce, ok := err.(http2connError); ok {
  1923  			return nil, fr.connError(ce.Code, ce.Reason)
  1924  		}
  1925  		return nil, err
  1926  	}
  1927  	if err := fr.checkFrameOrder(f); err != nil {
  1928  		return nil, err
  1929  	}
  1930  	if fr.logReads {
  1931  		fr.debugReadLoggerf("http2: Framer %p: read %v", fr, http2summarizeFrame(f))
  1932  	}
  1933  	if fh.Type == http2FrameHeaders && fr.ReadMetaHeaders != nil {
  1934  		return fr.readMetaFrame(f.(*http2HeadersFrame))
  1935  	}
  1936  	return f, nil
  1937  }
  1938  
  1939  // connError returns ConnectionError(code) but first
  1940  // stashes away a public reason to the caller can optionally relay it
  1941  // to the peer before hanging up on them. This might help others debug
  1942  // their implementations.
  1943  func (fr *http2Framer) connError(code http2ErrCode, reason string) error {
  1944  	fr.errDetail = errors.New(reason)
  1945  	return http2ConnectionError(code)
  1946  }
  1947  
  1948  // checkFrameOrder reports an error if f is an invalid frame to return
  1949  // next from ReadFrame. Mostly it checks whether HEADERS and
  1950  // CONTINUATION frames are contiguous.
  1951  func (fr *http2Framer) checkFrameOrder(f http2Frame) error {
  1952  	last := fr.lastFrame
  1953  	fr.lastFrame = f
  1954  	if fr.AllowIllegalReads {
  1955  		return nil
  1956  	}
  1957  
  1958  	fh := f.Header()
  1959  	if fr.lastHeaderStream != 0 {
  1960  		if fh.Type != http2FrameContinuation {
  1961  			return fr.connError(http2ErrCodeProtocol,
  1962  				fmt.Sprintf("got %s for stream %d; expected CONTINUATION following %s for stream %d",
  1963  					fh.Type, fh.StreamID,
  1964  					last.Header().Type, fr.lastHeaderStream))
  1965  		}
  1966  		if fh.StreamID != fr.lastHeaderStream {
  1967  			return fr.connError(http2ErrCodeProtocol,
  1968  				fmt.Sprintf("got CONTINUATION for stream %d; expected stream %d",
  1969  					fh.StreamID, fr.lastHeaderStream))
  1970  		}
  1971  	} else if fh.Type == http2FrameContinuation {
  1972  		return fr.connError(http2ErrCodeProtocol, fmt.Sprintf("unexpected CONTINUATION for stream %d", fh.StreamID))
  1973  	}
  1974  
  1975  	switch fh.Type {
  1976  	case http2FrameHeaders, http2FrameContinuation:
  1977  		if fh.Flags.Has(http2FlagHeadersEndHeaders) {
  1978  			fr.lastHeaderStream = 0
  1979  		} else {
  1980  			fr.lastHeaderStream = fh.StreamID
  1981  		}
  1982  	}
  1983  
  1984  	return nil
  1985  }
  1986  
  1987  // A DataFrame conveys arbitrary, variable-length sequences of octets
  1988  // associated with a stream.
  1989  // See https://httpwg.org/specs/rfc7540.html#rfc.section.6.1
  1990  type http2DataFrame struct {
  1991  	http2FrameHeader
  1992  	data []byte
  1993  }
  1994  
  1995  func (f *http2DataFrame) StreamEnded() bool {
  1996  	return f.http2FrameHeader.Flags.Has(http2FlagDataEndStream)
  1997  }
  1998  
  1999  // Data returns the frame's data octets, not including any padding
  2000  // size byte or padding suffix bytes.
  2001  // The caller must not retain the returned memory past the next
  2002  // call to ReadFrame.
  2003  func (f *http2DataFrame) Data() []byte {
  2004  	f.checkValid()
  2005  	return f.data
  2006  }
  2007  
  2008  func http2parseDataFrame(fc *http2frameCache, fh http2FrameHeader, countError func(string), payload []byte) (http2Frame, error) {
  2009  	if fh.StreamID == 0 {
  2010  		// DATA frames MUST be associated with a stream. If a
  2011  		// DATA frame is received whose stream identifier
  2012  		// field is 0x0, the recipient MUST respond with a
  2013  		// connection error (Section 5.4.1) of type
  2014  		// PROTOCOL_ERROR.
  2015  		countError("frame_data_stream_0")
  2016  		return nil, http2connError{http2ErrCodeProtocol, "DATA frame with stream ID 0"}
  2017  	}
  2018  	f := fc.getDataFrame()
  2019  	f.http2FrameHeader = fh
  2020  
  2021  	var padSize byte
  2022  	if fh.Flags.Has(http2FlagDataPadded) {
  2023  		var err error
  2024  		payload, padSize, err = http2readByte(payload)
  2025  		if err != nil {
  2026  			countError("frame_data_pad_byte_short")
  2027  			return nil, err
  2028  		}
  2029  	}
  2030  	if int(padSize) > len(payload) {
  2031  		// If the length of the padding is greater than the
  2032  		// length of the frame payload, the recipient MUST
  2033  		// treat this as a connection error.
  2034  		// Filed: https://github.com/http2/http2-spec/issues/610
  2035  		countError("frame_data_pad_too_big")
  2036  		return nil, http2connError{http2ErrCodeProtocol, "pad size larger than data payload"}
  2037  	}
  2038  	f.data = payload[:len(payload)-int(padSize)]
  2039  	return f, nil
  2040  }
  2041  
  2042  var (
  2043  	http2errStreamID    = errors.New("invalid stream ID")
  2044  	http2errDepStreamID = errors.New("invalid dependent stream ID")
  2045  	http2errPadLength   = errors.New("pad length too large")
  2046  	http2errPadBytes    = errors.New("padding bytes must all be zeros unless AllowIllegalWrites is enabled")
  2047  )
  2048  
  2049  func http2validStreamIDOrZero(streamID uint32) bool {
  2050  	return streamID&(1<<31) == 0
  2051  }
  2052  
  2053  func http2validStreamID(streamID uint32) bool {
  2054  	return streamID != 0 && streamID&(1<<31) == 0
  2055  }
  2056  
  2057  // WriteData writes a DATA frame.
  2058  //
  2059  // It will perform exactly one Write to the underlying Writer.
  2060  // It is the caller's responsibility not to violate the maximum frame size
  2061  // and to not call other Write methods concurrently.
  2062  func (f *http2Framer) WriteData(streamID uint32, endStream bool, data []byte) error {
  2063  	return f.WriteDataPadded(streamID, endStream, data, nil)
  2064  }
  2065  
  2066  // WriteDataPadded writes a DATA frame with optional padding.
  2067  //
  2068  // If pad is nil, the padding bit is not sent.
  2069  // The length of pad must not exceed 255 bytes.
  2070  // The bytes of pad must all be zero, unless f.AllowIllegalWrites is set.
  2071  //
  2072  // It will perform exactly one Write to the underlying Writer.
  2073  // It is the caller's responsibility not to violate the maximum frame size
  2074  // and to not call other Write methods concurrently.
  2075  func (f *http2Framer) WriteDataPadded(streamID uint32, endStream bool, data, pad []byte) error {
  2076  	if err := f.startWriteDataPadded(streamID, endStream, data, pad); err != nil {
  2077  		return err
  2078  	}
  2079  	return f.endWrite()
  2080  }
  2081  
  2082  // startWriteDataPadded is WriteDataPadded, but only writes the frame to the Framer's internal buffer.
  2083  // The caller should call endWrite to flush the frame to the underlying writer.
  2084  func (f *http2Framer) startWriteDataPadded(streamID uint32, endStream bool, data, pad []byte) error {
  2085  	if !http2validStreamID(streamID) && !f.AllowIllegalWrites {
  2086  		return http2errStreamID
  2087  	}
  2088  	if len(pad) > 0 {
  2089  		if len(pad) > 255 {
  2090  			return http2errPadLength
  2091  		}
  2092  		if !f.AllowIllegalWrites {
  2093  			for _, b := range pad {
  2094  				if b != 0 {
  2095  					// "Padding octets MUST be set to zero when sending."
  2096  					return http2errPadBytes
  2097  				}
  2098  			}
  2099  		}
  2100  	}
  2101  	var flags http2Flags
  2102  	if endStream {
  2103  		flags |= http2FlagDataEndStream
  2104  	}
  2105  	if pad != nil {
  2106  		flags |= http2FlagDataPadded
  2107  	}
  2108  	f.startWrite(http2FrameData, flags, streamID)
  2109  	if pad != nil {
  2110  		f.wbuf = append(f.wbuf, byte(len(pad)))
  2111  	}
  2112  	f.wbuf = append(f.wbuf, data...)
  2113  	f.wbuf = append(f.wbuf, pad...)
  2114  	return nil
  2115  }
  2116  
  2117  // A SettingsFrame conveys configuration parameters that affect how
  2118  // endpoints communicate, such as preferences and constraints on peer
  2119  // behavior.
  2120  //
  2121  // See https://httpwg.org/specs/rfc7540.html#SETTINGS
  2122  type http2SettingsFrame struct {
  2123  	http2FrameHeader
  2124  	p []byte
  2125  }
  2126  
  2127  func http2parseSettingsFrame(_ *http2frameCache, fh http2FrameHeader, countError func(string), p []byte) (http2Frame, error) {
  2128  	if fh.Flags.Has(http2FlagSettingsAck) && fh.Length > 0 {
  2129  		// When this (ACK 0x1) bit is set, the payload of the
  2130  		// SETTINGS frame MUST be empty. Receipt of a
  2131  		// SETTINGS frame with the ACK flag set and a length
  2132  		// field value other than 0 MUST be treated as a
  2133  		// connection error (Section 5.4.1) of type
  2134  		// FRAME_SIZE_ERROR.
  2135  		countError("frame_settings_ack_with_length")
  2136  		return nil, http2ConnectionError(http2ErrCodeFrameSize)
  2137  	}
  2138  	if fh.StreamID != 0 {
  2139  		// SETTINGS frames always apply to a connection,
  2140  		// never a single stream. The stream identifier for a
  2141  		// SETTINGS frame MUST be zero (0x0).  If an endpoint
  2142  		// receives a SETTINGS frame whose stream identifier
  2143  		// field is anything other than 0x0, the endpoint MUST
  2144  		// respond with a connection error (Section 5.4.1) of
  2145  		// type PROTOCOL_ERROR.
  2146  		countError("frame_settings_has_stream")
  2147  		return nil, http2ConnectionError(http2ErrCodeProtocol)
  2148  	}
  2149  	if len(p)%6 != 0 {
  2150  		countError("frame_settings_mod_6")
  2151  		// Expecting even number of 6 byte settings.
  2152  		return nil, http2ConnectionError(http2ErrCodeFrameSize)
  2153  	}
  2154  	f := &http2SettingsFrame{http2FrameHeader: fh, p: p}
  2155  	if v, ok := f.Value(http2SettingInitialWindowSize); ok && v > (1<<31)-1 {
  2156  		countError("frame_settings_window_size_too_big")
  2157  		// Values above the maximum flow control window size of 2^31 - 1 MUST
  2158  		// be treated as a connection error (Section 5.4.1) of type
  2159  		// FLOW_CONTROL_ERROR.
  2160  		return nil, http2ConnectionError(http2ErrCodeFlowControl)
  2161  	}
  2162  	return f, nil
  2163  }
  2164  
  2165  func (f *http2SettingsFrame) IsAck() bool {
  2166  	return f.http2FrameHeader.Flags.Has(http2FlagSettingsAck)
  2167  }
  2168  
  2169  func (f *http2SettingsFrame) Value(id http2SettingID) (v uint32, ok bool) {
  2170  	f.checkValid()
  2171  	for i := 0; i < f.NumSettings(); i++ {
  2172  		if s := f.Setting(i); s.ID == id {
  2173  			return s.Val, true
  2174  		}
  2175  	}
  2176  	return 0, false
  2177  }
  2178  
  2179  // Setting returns the setting from the frame at the given 0-based index.
  2180  // The index must be >= 0 and less than f.NumSettings().
  2181  func (f *http2SettingsFrame) Setting(i int) http2Setting {
  2182  	buf := f.p
  2183  	return http2Setting{
  2184  		ID:  http2SettingID(binary.BigEndian.Uint16(buf[i*6 : i*6+2])),
  2185  		Val: binary.BigEndian.Uint32(buf[i*6+2 : i*6+6]),
  2186  	}
  2187  }
  2188  
  2189  func (f *http2SettingsFrame) NumSettings() int { return len(f.p) / 6 }
  2190  
  2191  // HasDuplicates reports whether f contains any duplicate setting IDs.
  2192  func (f *http2SettingsFrame) HasDuplicates() bool {
  2193  	num := f.NumSettings()
  2194  	if num == 0 {
  2195  		return false
  2196  	}
  2197  	// If it's small enough (the common case), just do the n^2
  2198  	// thing and avoid a map allocation.
  2199  	if num < 10 {
  2200  		for i := 0; i < num; i++ {
  2201  			idi := f.Setting(i).ID
  2202  			for j := i + 1; j < num; j++ {
  2203  				idj := f.Setting(j).ID
  2204  				if idi == idj {
  2205  					return true
  2206  				}
  2207  			}
  2208  		}
  2209  		return false
  2210  	}
  2211  	seen := map[http2SettingID]bool{}
  2212  	for i := 0; i < num; i++ {
  2213  		id := f.Setting(i).ID
  2214  		if seen[id] {
  2215  			return true
  2216  		}
  2217  		seen[id] = true
  2218  	}
  2219  	return false
  2220  }
  2221  
  2222  // ForeachSetting runs fn for each setting.
  2223  // It stops and returns the first error.
  2224  func (f *http2SettingsFrame) ForeachSetting(fn func(http2Setting) error) error {
  2225  	f.checkValid()
  2226  	for i := 0; i < f.NumSettings(); i++ {
  2227  		if err := fn(f.Setting(i)); err != nil {
  2228  			return err
  2229  		}
  2230  	}
  2231  	return nil
  2232  }
  2233  
  2234  // WriteSettings writes a SETTINGS frame with zero or more settings
  2235  // specified and the ACK bit not set.
  2236  //
  2237  // It will perform exactly one Write to the underlying Writer.
  2238  // It is the caller's responsibility to not call other Write methods concurrently.
  2239  func (f *http2Framer) WriteSettings(settings ...http2Setting) error {
  2240  	f.startWrite(http2FrameSettings, 0, 0)
  2241  	for _, s := range settings {
  2242  		f.writeUint16(uint16(s.ID))
  2243  		f.writeUint32(s.Val)
  2244  	}
  2245  	return f.endWrite()
  2246  }
  2247  
  2248  // WriteSettingsAck writes an empty SETTINGS frame with the ACK bit set.
  2249  //
  2250  // It will perform exactly one Write to the underlying Writer.
  2251  // It is the caller's responsibility to not call other Write methods concurrently.
  2252  func (f *http2Framer) WriteSettingsAck() error {
  2253  	f.startWrite(http2FrameSettings, http2FlagSettingsAck, 0)
  2254  	return f.endWrite()
  2255  }
  2256  
  2257  // A PingFrame is a mechanism for measuring a minimal round trip time
  2258  // from the sender, as well as determining whether an idle connection
  2259  // is still functional.
  2260  // See https://httpwg.org/specs/rfc7540.html#rfc.section.6.7
  2261  type http2PingFrame struct {
  2262  	http2FrameHeader
  2263  	Data [8]byte
  2264  }
  2265  
  2266  func (f *http2PingFrame) IsAck() bool { return f.Flags.Has(http2FlagPingAck) }
  2267  
  2268  func http2parsePingFrame(_ *http2frameCache, fh http2FrameHeader, countError func(string), payload []byte) (http2Frame, error) {
  2269  	if len(payload) != 8 {
  2270  		countError("frame_ping_length")
  2271  		return nil, http2ConnectionError(http2ErrCodeFrameSize)
  2272  	}
  2273  	if fh.StreamID != 0 {
  2274  		countError("frame_ping_has_stream")
  2275  		return nil, http2ConnectionError(http2ErrCodeProtocol)
  2276  	}
  2277  	f := &http2PingFrame{http2FrameHeader: fh}
  2278  	copy(f.Data[:], payload)
  2279  	return f, nil
  2280  }
  2281  
  2282  func (f *http2Framer) WritePing(ack bool, data [8]byte) error {
  2283  	var flags http2Flags
  2284  	if ack {
  2285  		flags = http2FlagPingAck
  2286  	}
  2287  	f.startWrite(http2FramePing, flags, 0)
  2288  	f.writeBytes(data[:])
  2289  	return f.endWrite()
  2290  }
  2291  
  2292  // A GoAwayFrame informs the remote peer to stop creating streams on this connection.
  2293  // See https://httpwg.org/specs/rfc7540.html#rfc.section.6.8
  2294  type http2GoAwayFrame struct {
  2295  	http2FrameHeader
  2296  	LastStreamID uint32
  2297  	ErrCode      http2ErrCode
  2298  	debugData    []byte
  2299  }
  2300  
  2301  // DebugData returns any debug data in the GOAWAY frame. Its contents
  2302  // are not defined.
  2303  // The caller must not retain the returned memory past the next
  2304  // call to ReadFrame.
  2305  func (f *http2GoAwayFrame) DebugData() []byte {
  2306  	f.checkValid()
  2307  	return f.debugData
  2308  }
  2309  
  2310  func http2parseGoAwayFrame(_ *http2frameCache, fh http2FrameHeader, countError func(string), p []byte) (http2Frame, error) {
  2311  	if fh.StreamID != 0 {
  2312  		countError("frame_goaway_has_stream")
  2313  		return nil, http2ConnectionError(http2ErrCodeProtocol)
  2314  	}
  2315  	if len(p) < 8 {
  2316  		countError("frame_goaway_short")
  2317  		return nil, http2ConnectionError(http2ErrCodeFrameSize)
  2318  	}
  2319  	return &http2GoAwayFrame{
  2320  		http2FrameHeader: fh,
  2321  		LastStreamID:     binary.BigEndian.Uint32(p[:4]) & (1<<31 - 1),
  2322  		ErrCode:          http2ErrCode(binary.BigEndian.Uint32(p[4:8])),
  2323  		debugData:        p[8:],
  2324  	}, nil
  2325  }
  2326  
  2327  func (f *http2Framer) WriteGoAway(maxStreamID uint32, code http2ErrCode, debugData []byte) error {
  2328  	f.startWrite(http2FrameGoAway, 0, 0)
  2329  	f.writeUint32(maxStreamID & (1<<31 - 1))
  2330  	f.writeUint32(uint32(code))
  2331  	f.writeBytes(debugData)
  2332  	return f.endWrite()
  2333  }
  2334  
  2335  // An UnknownFrame is the frame type returned when the frame type is unknown
  2336  // or no specific frame type parser exists.
  2337  type http2UnknownFrame struct {
  2338  	http2FrameHeader
  2339  	p []byte
  2340  }
  2341  
  2342  // Payload returns the frame's payload (after the header).  It is not
  2343  // valid to call this method after a subsequent call to
  2344  // Framer.ReadFrame, nor is it valid to retain the returned slice.
  2345  // The memory is owned by the Framer and is invalidated when the next
  2346  // frame is read.
  2347  func (f *http2UnknownFrame) Payload() []byte {
  2348  	f.checkValid()
  2349  	return f.p
  2350  }
  2351  
  2352  func http2parseUnknownFrame(_ *http2frameCache, fh http2FrameHeader, countError func(string), p []byte) (http2Frame, error) {
  2353  	return &http2UnknownFrame{fh, p}, nil
  2354  }
  2355  
  2356  // A WindowUpdateFrame is used to implement flow control.
  2357  // See https://httpwg.org/specs/rfc7540.html#rfc.section.6.9
  2358  type http2WindowUpdateFrame struct {
  2359  	http2FrameHeader
  2360  	Increment uint32 // never read with high bit set
  2361  }
  2362  
  2363  func http2parseWindowUpdateFrame(_ *http2frameCache, fh http2FrameHeader, countError func(string), p []byte) (http2Frame, error) {
  2364  	if len(p) != 4 {
  2365  		countError("frame_windowupdate_bad_len")
  2366  		return nil, http2ConnectionError(http2ErrCodeFrameSize)
  2367  	}
  2368  	inc := binary.BigEndian.Uint32(p[:4]) & 0x7fffffff // mask off high reserved bit
  2369  	if inc == 0 {
  2370  		// A receiver MUST treat the receipt of a
  2371  		// WINDOW_UPDATE frame with an flow control window
  2372  		// increment of 0 as a stream error (Section 5.4.2) of
  2373  		// type PROTOCOL_ERROR; errors on the connection flow
  2374  		// control window MUST be treated as a connection
  2375  		// error (Section 5.4.1).
  2376  		if fh.StreamID == 0 {
  2377  			countError("frame_windowupdate_zero_inc_conn")
  2378  			return nil, http2ConnectionError(http2ErrCodeProtocol)
  2379  		}
  2380  		countError("frame_windowupdate_zero_inc_stream")
  2381  		return nil, http2streamError(fh.StreamID, http2ErrCodeProtocol)
  2382  	}
  2383  	return &http2WindowUpdateFrame{
  2384  		http2FrameHeader: fh,
  2385  		Increment:        inc,
  2386  	}, nil
  2387  }
  2388  
  2389  // WriteWindowUpdate writes a WINDOW_UPDATE frame.
  2390  // The increment value must be between 1 and 2,147,483,647, inclusive.
  2391  // If the Stream ID is zero, the window update applies to the
  2392  // connection as a whole.
  2393  func (f *http2Framer) WriteWindowUpdate(streamID, incr uint32) error {
  2394  	// "The legal range for the increment to the flow control window is 1 to 2^31-1 (2,147,483,647) octets."
  2395  	if (incr < 1 || incr > 2147483647) && !f.AllowIllegalWrites {
  2396  		return errors.New("illegal window increment value")
  2397  	}
  2398  	f.startWrite(http2FrameWindowUpdate, 0, streamID)
  2399  	f.writeUint32(incr)
  2400  	return f.endWrite()
  2401  }
  2402  
  2403  // A HeadersFrame is used to open a stream and additionally carries a
  2404  // header block fragment.
  2405  type http2HeadersFrame struct {
  2406  	http2FrameHeader
  2407  
  2408  	// Priority is set if FlagHeadersPriority is set in the FrameHeader.
  2409  	Priority http2PriorityParam
  2410  
  2411  	headerFragBuf []byte // not owned
  2412  }
  2413  
  2414  func (f *http2HeadersFrame) HeaderBlockFragment() []byte {
  2415  	f.checkValid()
  2416  	return f.headerFragBuf
  2417  }
  2418  
  2419  func (f *http2HeadersFrame) HeadersEnded() bool {
  2420  	return f.http2FrameHeader.Flags.Has(http2FlagHeadersEndHeaders)
  2421  }
  2422  
  2423  func (f *http2HeadersFrame) StreamEnded() bool {
  2424  	return f.http2FrameHeader.Flags.Has(http2FlagHeadersEndStream)
  2425  }
  2426  
  2427  func (f *http2HeadersFrame) HasPriority() bool {
  2428  	return f.http2FrameHeader.Flags.Has(http2FlagHeadersPriority)
  2429  }
  2430  
  2431  func http2parseHeadersFrame(_ *http2frameCache, fh http2FrameHeader, countError func(string), p []byte) (_ http2Frame, err error) {
  2432  	hf := &http2HeadersFrame{
  2433  		http2FrameHeader: fh,
  2434  	}
  2435  	if fh.StreamID == 0 {
  2436  		// HEADERS frames MUST be associated with a stream. If a HEADERS frame
  2437  		// is received whose stream identifier field is 0x0, the recipient MUST
  2438  		// respond with a connection error (Section 5.4.1) of type
  2439  		// PROTOCOL_ERROR.
  2440  		countError("frame_headers_zero_stream")
  2441  		return nil, http2connError{http2ErrCodeProtocol, "HEADERS frame with stream ID 0"}
  2442  	}
  2443  	var padLength uint8
  2444  	if fh.Flags.Has(http2FlagHeadersPadded) {
  2445  		if p, padLength, err = http2readByte(p); err != nil {
  2446  			countError("frame_headers_pad_short")
  2447  			return
  2448  		}
  2449  	}
  2450  	if fh.Flags.Has(http2FlagHeadersPriority) {
  2451  		var v uint32
  2452  		p, v, err = http2readUint32(p)
  2453  		if err != nil {
  2454  			countError("frame_headers_prio_short")
  2455  			return nil, err
  2456  		}
  2457  		hf.Priority.StreamDep = v & 0x7fffffff
  2458  		hf.Priority.Exclusive = (v != hf.Priority.StreamDep) // high bit was set
  2459  		p, hf.Priority.Weight, err = http2readByte(p)
  2460  		if err != nil {
  2461  			countError("frame_headers_prio_weight_short")
  2462  			return nil, err
  2463  		}
  2464  	}
  2465  	if len(p)-int(padLength) < 0 {
  2466  		countError("frame_headers_pad_too_big")
  2467  		return nil, http2streamError(fh.StreamID, http2ErrCodeProtocol)
  2468  	}
  2469  	hf.headerFragBuf = p[:len(p)-int(padLength)]
  2470  	return hf, nil
  2471  }
  2472  
  2473  // HeadersFrameParam are the parameters for writing a HEADERS frame.
  2474  type http2HeadersFrameParam struct {
  2475  	// StreamID is the required Stream ID to initiate.
  2476  	StreamID uint32
  2477  	// BlockFragment is part (or all) of a Header Block.
  2478  	BlockFragment []byte
  2479  
  2480  	// EndStream indicates that the header block is the last that
  2481  	// the endpoint will send for the identified stream. Setting
  2482  	// this flag causes the stream to enter one of "half closed"
  2483  	// states.
  2484  	EndStream bool
  2485  
  2486  	// EndHeaders indicates that this frame contains an entire
  2487  	// header block and is not followed by any
  2488  	// CONTINUATION frames.
  2489  	EndHeaders bool
  2490  
  2491  	// PadLength is the optional number of bytes of zeros to add
  2492  	// to this frame.
  2493  	PadLength uint8
  2494  
  2495  	// Priority, if non-zero, includes stream priority information
  2496  	// in the HEADER frame.
  2497  	Priority http2PriorityParam
  2498  }
  2499  
  2500  // WriteHeaders writes a single HEADERS frame.
  2501  //
  2502  // This is a low-level header writing method. Encoding headers and
  2503  // splitting them into any necessary CONTINUATION frames is handled
  2504  // elsewhere.
  2505  //
  2506  // It will perform exactly one Write to the underlying Writer.
  2507  // It is the caller's responsibility to not call other Write methods concurrently.
  2508  func (f *http2Framer) WriteHeaders(p http2HeadersFrameParam) error {
  2509  	if !http2validStreamID(p.StreamID) && !f.AllowIllegalWrites {
  2510  		return http2errStreamID
  2511  	}
  2512  	var flags http2Flags
  2513  	if p.PadLength != 0 {
  2514  		flags |= http2FlagHeadersPadded
  2515  	}
  2516  	if p.EndStream {
  2517  		flags |= http2FlagHeadersEndStream
  2518  	}
  2519  	if p.EndHeaders {
  2520  		flags |= http2FlagHeadersEndHeaders
  2521  	}
  2522  	if !p.Priority.IsZero() {
  2523  		flags |= http2FlagHeadersPriority
  2524  	}
  2525  	f.startWrite(http2FrameHeaders, flags, p.StreamID)
  2526  	if p.PadLength != 0 {
  2527  		f.writeByte(p.PadLength)
  2528  	}
  2529  	if !p.Priority.IsZero() {
  2530  		v := p.Priority.StreamDep
  2531  		if !http2validStreamIDOrZero(v) && !f.AllowIllegalWrites {
  2532  			return http2errDepStreamID
  2533  		}
  2534  		if p.Priority.Exclusive {
  2535  			v |= 1 << 31
  2536  		}
  2537  		f.writeUint32(v)
  2538  		f.writeByte(p.Priority.Weight)
  2539  	}
  2540  	f.wbuf = append(f.wbuf, p.BlockFragment...)
  2541  	f.wbuf = append(f.wbuf, http2padZeros[:p.PadLength]...)
  2542  	return f.endWrite()
  2543  }
  2544  
  2545  // A PriorityFrame specifies the sender-advised priority of a stream.
  2546  // See https://httpwg.org/specs/rfc7540.html#rfc.section.6.3
  2547  type http2PriorityFrame struct {
  2548  	http2FrameHeader
  2549  	http2PriorityParam
  2550  }
  2551  
  2552  // PriorityParam are the stream prioritzation parameters.
  2553  type http2PriorityParam struct {
  2554  	// StreamDep is a 31-bit stream identifier for the
  2555  	// stream that this stream depends on. Zero means no
  2556  	// dependency.
  2557  	StreamDep uint32
  2558  
  2559  	// Exclusive is whether the dependency is exclusive.
  2560  	Exclusive bool
  2561  
  2562  	// Weight is the stream's zero-indexed weight. It should be
  2563  	// set together with StreamDep, or neither should be set. Per
  2564  	// the spec, "Add one to the value to obtain a weight between
  2565  	// 1 and 256."
  2566  	Weight uint8
  2567  }
  2568  
  2569  func (p http2PriorityParam) IsZero() bool {
  2570  	return p == http2PriorityParam{}
  2571  }
  2572  
  2573  func http2parsePriorityFrame(_ *http2frameCache, fh http2FrameHeader, countError func(string), payload []byte) (http2Frame, error) {
  2574  	if fh.StreamID == 0 {
  2575  		countError("frame_priority_zero_stream")
  2576  		return nil, http2connError{http2ErrCodeProtocol, "PRIORITY frame with stream ID 0"}
  2577  	}
  2578  	if len(payload) != 5 {
  2579  		countError("frame_priority_bad_length")
  2580  		return nil, http2connError{http2ErrCodeFrameSize, fmt.Sprintf("PRIORITY frame payload size was %d; want 5", len(payload))}
  2581  	}
  2582  	v := binary.BigEndian.Uint32(payload[:4])
  2583  	streamID := v & 0x7fffffff // mask off high bit
  2584  	return &http2PriorityFrame{
  2585  		http2FrameHeader: fh,
  2586  		http2PriorityParam: http2PriorityParam{
  2587  			Weight:    payload[4],
  2588  			StreamDep: streamID,
  2589  			Exclusive: streamID != v, // was high bit set?
  2590  		},
  2591  	}, nil
  2592  }
  2593  
  2594  // WritePriority writes a PRIORITY frame.
  2595  //
  2596  // It will perform exactly one Write to the underlying Writer.
  2597  // It is the caller's responsibility to not call other Write methods concurrently.
  2598  func (f *http2Framer) WritePriority(streamID uint32, p http2PriorityParam) error {
  2599  	if !http2validStreamID(streamID) && !f.AllowIllegalWrites {
  2600  		return http2errStreamID
  2601  	}
  2602  	if !http2validStreamIDOrZero(p.StreamDep) {
  2603  		return http2errDepStreamID
  2604  	}
  2605  	f.startWrite(http2FramePriority, 0, streamID)
  2606  	v := p.StreamDep
  2607  	if p.Exclusive {
  2608  		v |= 1 << 31
  2609  	}
  2610  	f.writeUint32(v)
  2611  	f.writeByte(p.Weight)
  2612  	return f.endWrite()
  2613  }
  2614  
  2615  // A RSTStreamFrame allows for abnormal termination of a stream.
  2616  // See https://httpwg.org/specs/rfc7540.html#rfc.section.6.4
  2617  type http2RSTStreamFrame struct {
  2618  	http2FrameHeader
  2619  	ErrCode http2ErrCode
  2620  }
  2621  
  2622  func http2parseRSTStreamFrame(_ *http2frameCache, fh http2FrameHeader, countError func(string), p []byte) (http2Frame, error) {
  2623  	if len(p) != 4 {
  2624  		countError("frame_rststream_bad_len")
  2625  		return nil, http2ConnectionError(http2ErrCodeFrameSize)
  2626  	}
  2627  	if fh.StreamID == 0 {
  2628  		countError("frame_rststream_zero_stream")
  2629  		return nil, http2ConnectionError(http2ErrCodeProtocol)
  2630  	}
  2631  	return &http2RSTStreamFrame{fh, http2ErrCode(binary.BigEndian.Uint32(p[:4]))}, nil
  2632  }
  2633  
  2634  // WriteRSTStream writes a RST_STREAM frame.
  2635  //
  2636  // It will perform exactly one Write to the underlying Writer.
  2637  // It is the caller's responsibility to not call other Write methods concurrently.
  2638  func (f *http2Framer) WriteRSTStream(streamID uint32, code http2ErrCode) error {
  2639  	if !http2validStreamID(streamID) && !f.AllowIllegalWrites {
  2640  		return http2errStreamID
  2641  	}
  2642  	f.startWrite(http2FrameRSTStream, 0, streamID)
  2643  	f.writeUint32(uint32(code))
  2644  	return f.endWrite()
  2645  }
  2646  
  2647  // A ContinuationFrame is used to continue a sequence of header block fragments.
  2648  // See https://httpwg.org/specs/rfc7540.html#rfc.section.6.10
  2649  type http2ContinuationFrame struct {
  2650  	http2FrameHeader
  2651  	headerFragBuf []byte
  2652  }
  2653  
  2654  func http2parseContinuationFrame(_ *http2frameCache, fh http2FrameHeader, countError func(string), p []byte) (http2Frame, error) {
  2655  	if fh.StreamID == 0 {
  2656  		countError("frame_continuation_zero_stream")
  2657  		return nil, http2connError{http2ErrCodeProtocol, "CONTINUATION frame with stream ID 0"}
  2658  	}
  2659  	return &http2ContinuationFrame{fh, p}, nil
  2660  }
  2661  
  2662  func (f *http2ContinuationFrame) HeaderBlockFragment() []byte {
  2663  	f.checkValid()
  2664  	return f.headerFragBuf
  2665  }
  2666  
  2667  func (f *http2ContinuationFrame) HeadersEnded() bool {
  2668  	return f.http2FrameHeader.Flags.Has(http2FlagContinuationEndHeaders)
  2669  }
  2670  
  2671  // WriteContinuation writes a CONTINUATION frame.
  2672  //
  2673  // It will perform exactly one Write to the underlying Writer.
  2674  // It is the caller's responsibility to not call other Write methods concurrently.
  2675  func (f *http2Framer) WriteContinuation(streamID uint32, endHeaders bool, headerBlockFragment []byte) error {
  2676  	if !http2validStreamID(streamID) && !f.AllowIllegalWrites {
  2677  		return http2errStreamID
  2678  	}
  2679  	var flags http2Flags
  2680  	if endHeaders {
  2681  		flags |= http2FlagContinuationEndHeaders
  2682  	}
  2683  	f.startWrite(http2FrameContinuation, flags, streamID)
  2684  	f.wbuf = append(f.wbuf, headerBlockFragment...)
  2685  	return f.endWrite()
  2686  }
  2687  
  2688  // A PushPromiseFrame is used to initiate a server stream.
  2689  // See https://httpwg.org/specs/rfc7540.html#rfc.section.6.6
  2690  type http2PushPromiseFrame struct {
  2691  	http2FrameHeader
  2692  	PromiseID     uint32
  2693  	headerFragBuf []byte // not owned
  2694  }
  2695  
  2696  func (f *http2PushPromiseFrame) HeaderBlockFragment() []byte {
  2697  	f.checkValid()
  2698  	return f.headerFragBuf
  2699  }
  2700  
  2701  func (f *http2PushPromiseFrame) HeadersEnded() bool {
  2702  	return f.http2FrameHeader.Flags.Has(http2FlagPushPromiseEndHeaders)
  2703  }
  2704  
  2705  func http2parsePushPromise(_ *http2frameCache, fh http2FrameHeader, countError func(string), p []byte) (_ http2Frame, err error) {
  2706  	pp := &http2PushPromiseFrame{
  2707  		http2FrameHeader: fh,
  2708  	}
  2709  	if pp.StreamID == 0 {
  2710  		// PUSH_PROMISE frames MUST be associated with an existing,
  2711  		// peer-initiated stream. The stream identifier of a
  2712  		// PUSH_PROMISE frame indicates the stream it is associated
  2713  		// with. If the stream identifier field specifies the value
  2714  		// 0x0, a recipient MUST respond with a connection error
  2715  		// (Section 5.4.1) of type PROTOCOL_ERROR.
  2716  		countError("frame_pushpromise_zero_stream")
  2717  		return nil, http2ConnectionError(http2ErrCodeProtocol)
  2718  	}
  2719  	// The PUSH_PROMISE frame includes optional padding.
  2720  	// Padding fields and flags are identical to those defined for DATA frames
  2721  	var padLength uint8
  2722  	if fh.Flags.Has(http2FlagPushPromisePadded) {
  2723  		if p, padLength, err = http2readByte(p); err != nil {
  2724  			countError("frame_pushpromise_pad_short")
  2725  			return
  2726  		}
  2727  	}
  2728  
  2729  	p, pp.PromiseID, err = http2readUint32(p)
  2730  	if err != nil {
  2731  		countError("frame_pushpromise_promiseid_short")
  2732  		return
  2733  	}
  2734  	pp.PromiseID = pp.PromiseID & (1<<31 - 1)
  2735  
  2736  	if int(padLength) > len(p) {
  2737  		// like the DATA frame, error out if padding is longer than the body.
  2738  		countError("frame_pushpromise_pad_too_big")
  2739  		return nil, http2ConnectionError(http2ErrCodeProtocol)
  2740  	}
  2741  	pp.headerFragBuf = p[:len(p)-int(padLength)]
  2742  	return pp, nil
  2743  }
  2744  
  2745  // PushPromiseParam are the parameters for writing a PUSH_PROMISE frame.
  2746  type http2PushPromiseParam struct {
  2747  	// StreamID is the required Stream ID to initiate.
  2748  	StreamID uint32
  2749  
  2750  	// PromiseID is the required Stream ID which this
  2751  	// Push Promises
  2752  	PromiseID uint32
  2753  
  2754  	// BlockFragment is part (or all) of a Header Block.
  2755  	BlockFragment []byte
  2756  
  2757  	// EndHeaders indicates that this frame contains an entire
  2758  	// header block and is not followed by any
  2759  	// CONTINUATION frames.
  2760  	EndHeaders bool
  2761  
  2762  	// PadLength is the optional number of bytes of zeros to add
  2763  	// to this frame.
  2764  	PadLength uint8
  2765  }
  2766  
  2767  // WritePushPromise writes a single PushPromise Frame.
  2768  //
  2769  // As with Header Frames, This is the low level call for writing
  2770  // individual frames. Continuation frames are handled elsewhere.
  2771  //
  2772  // It will perform exactly one Write to the underlying Writer.
  2773  // It is the caller's responsibility to not call other Write methods concurrently.
  2774  func (f *http2Framer) WritePushPromise(p http2PushPromiseParam) error {
  2775  	if !http2validStreamID(p.StreamID) && !f.AllowIllegalWrites {
  2776  		return http2errStreamID
  2777  	}
  2778  	var flags http2Flags
  2779  	if p.PadLength != 0 {
  2780  		flags |= http2FlagPushPromisePadded
  2781  	}
  2782  	if p.EndHeaders {
  2783  		flags |= http2FlagPushPromiseEndHeaders
  2784  	}
  2785  	f.startWrite(http2FramePushPromise, flags, p.StreamID)
  2786  	if p.PadLength != 0 {
  2787  		f.writeByte(p.PadLength)
  2788  	}
  2789  	if !http2validStreamID(p.PromiseID) && !f.AllowIllegalWrites {
  2790  		return http2errStreamID
  2791  	}
  2792  	f.writeUint32(p.PromiseID)
  2793  	f.wbuf = append(f.wbuf, p.BlockFragment...)
  2794  	f.wbuf = append(f.wbuf, http2padZeros[:p.PadLength]...)
  2795  	return f.endWrite()
  2796  }
  2797  
  2798  // WriteRawFrame writes a raw frame. This can be used to write
  2799  // extension frames unknown to this package.
  2800  func (f *http2Framer) WriteRawFrame(t http2FrameType, flags http2Flags, streamID uint32, payload []byte) error {
  2801  	f.startWrite(t, flags, streamID)
  2802  	f.writeBytes(payload)
  2803  	return f.endWrite()
  2804  }
  2805  
  2806  func http2readByte(p []byte) (remain []byte, b byte, err error) {
  2807  	if len(p) == 0 {
  2808  		return nil, 0, io.ErrUnexpectedEOF
  2809  	}
  2810  	return p[1:], p[0], nil
  2811  }
  2812  
  2813  func http2readUint32(p []byte) (remain []byte, v uint32, err error) {
  2814  	if len(p) < 4 {
  2815  		return nil, 0, io.ErrUnexpectedEOF
  2816  	}
  2817  	return p[4:], binary.BigEndian.Uint32(p[:4]), nil
  2818  }
  2819  
  2820  type http2streamEnder interface {
  2821  	StreamEnded() bool
  2822  }
  2823  
  2824  type http2headersEnder interface {
  2825  	HeadersEnded() bool
  2826  }
  2827  
  2828  type http2headersOrContinuation interface {
  2829  	http2headersEnder
  2830  	HeaderBlockFragment() []byte
  2831  }
  2832  
  2833  // A MetaHeadersFrame is the representation of one HEADERS frame and
  2834  // zero or more contiguous CONTINUATION frames and the decoding of
  2835  // their HPACK-encoded contents.
  2836  //
  2837  // This type of frame does not appear on the wire and is only returned
  2838  // by the Framer when Framer.ReadMetaHeaders is set.
  2839  type http2MetaHeadersFrame struct {
  2840  	*http2HeadersFrame
  2841  
  2842  	// Fields are the fields contained in the HEADERS and
  2843  	// CONTINUATION frames. The underlying slice is owned by the
  2844  	// Framer and must not be retained after the next call to
  2845  	// ReadFrame.
  2846  	//
  2847  	// Fields are guaranteed to be in the correct http2 order and
  2848  	// not have unknown pseudo header fields or invalid header
  2849  	// field names or values. Required pseudo header fields may be
  2850  	// missing, however. Use the MetaHeadersFrame.Pseudo accessor
  2851  	// method access pseudo headers.
  2852  	Fields []hpack.HeaderField
  2853  
  2854  	// Truncated is whether the max header list size limit was hit
  2855  	// and Fields is incomplete. The hpack decoder state is still
  2856  	// valid, however.
  2857  	Truncated bool
  2858  }
  2859  
  2860  // PseudoValue returns the given pseudo header field's value.
  2861  // The provided pseudo field should not contain the leading colon.
  2862  func (mh *http2MetaHeadersFrame) PseudoValue(pseudo string) string {
  2863  	for _, hf := range mh.Fields {
  2864  		if !hf.IsPseudo() {
  2865  			return ""
  2866  		}
  2867  		if hf.Name[1:] == pseudo {
  2868  			return hf.Value
  2869  		}
  2870  	}
  2871  	return ""
  2872  }
  2873  
  2874  // RegularFields returns the regular (non-pseudo) header fields of mh.
  2875  // The caller does not own the returned slice.
  2876  func (mh *http2MetaHeadersFrame) RegularFields() []hpack.HeaderField {
  2877  	for i, hf := range mh.Fields {
  2878  		if !hf.IsPseudo() {
  2879  			return mh.Fields[i:]
  2880  		}
  2881  	}
  2882  	return nil
  2883  }
  2884  
  2885  // PseudoFields returns the pseudo header fields of mh.
  2886  // The caller does not own the returned slice.
  2887  func (mh *http2MetaHeadersFrame) PseudoFields() []hpack.HeaderField {
  2888  	for i, hf := range mh.Fields {
  2889  		if !hf.IsPseudo() {
  2890  			return mh.Fields[:i]
  2891  		}
  2892  	}
  2893  	return mh.Fields
  2894  }
  2895  
  2896  func (mh *http2MetaHeadersFrame) checkPseudos() error {
  2897  	var isRequest, isResponse bool
  2898  	pf := mh.PseudoFields()
  2899  	for i, hf := range pf {
  2900  		switch hf.Name {
  2901  		case ":method", ":path", ":scheme", ":authority":
  2902  			isRequest = true
  2903  		case ":status":
  2904  			isResponse = true
  2905  		default:
  2906  			return http2pseudoHeaderError(hf.Name)
  2907  		}
  2908  		// Check for duplicates.
  2909  		// This would be a bad algorithm, but N is 4.
  2910  		// And this doesn't allocate.
  2911  		for _, hf2 := range pf[:i] {
  2912  			if hf.Name == hf2.Name {
  2913  				return http2duplicatePseudoHeaderError(hf.Name)
  2914  			}
  2915  		}
  2916  	}
  2917  	if isRequest && isResponse {
  2918  		return http2errMixPseudoHeaderTypes
  2919  	}
  2920  	return nil
  2921  }
  2922  
  2923  func (fr *http2Framer) maxHeaderStringLen() int {
  2924  	v := int(fr.maxHeaderListSize())
  2925  	if v < 0 {
  2926  		// If maxHeaderListSize overflows an int, use no limit (0).
  2927  		return 0
  2928  	}
  2929  	return v
  2930  }
  2931  
  2932  // readMetaFrame returns 0 or more CONTINUATION frames from fr and
  2933  // merge them into the provided hf and returns a MetaHeadersFrame
  2934  // with the decoded hpack values.
  2935  func (fr *http2Framer) readMetaFrame(hf *http2HeadersFrame) (http2Frame, error) {
  2936  	if fr.AllowIllegalReads {
  2937  		return nil, errors.New("illegal use of AllowIllegalReads with ReadMetaHeaders")
  2938  	}
  2939  	mh := &http2MetaHeadersFrame{
  2940  		http2HeadersFrame: hf,
  2941  	}
  2942  	var remainSize = fr.maxHeaderListSize()
  2943  	var sawRegular bool
  2944  
  2945  	var invalid error // pseudo header field errors
  2946  	hdec := fr.ReadMetaHeaders
  2947  	hdec.SetEmitEnabled(true)
  2948  	hdec.SetMaxStringLength(fr.maxHeaderStringLen())
  2949  	hdec.SetEmitFunc(func(hf hpack.HeaderField) {
  2950  		if http2VerboseLogs && fr.logReads {
  2951  			fr.debugReadLoggerf("http2: decoded hpack field %+v", hf)
  2952  		}
  2953  		if !httpguts.ValidHeaderFieldValue(hf.Value) {
  2954  			// Don't include the value in the error, because it may be sensitive.
  2955  			invalid = http2headerFieldValueError(hf.Name)
  2956  		}
  2957  		isPseudo := strings.HasPrefix(hf.Name, ":")
  2958  		if isPseudo {
  2959  			if sawRegular {
  2960  				invalid = http2errPseudoAfterRegular
  2961  			}
  2962  		} else {
  2963  			sawRegular = true
  2964  			if !http2validWireHeaderFieldName(hf.Name) {
  2965  				invalid = http2headerFieldNameError(hf.Name)
  2966  			}
  2967  		}
  2968  
  2969  		if invalid != nil {
  2970  			hdec.SetEmitEnabled(false)
  2971  			return
  2972  		}
  2973  
  2974  		size := hf.Size()
  2975  		if size > remainSize {
  2976  			hdec.SetEmitEnabled(false)
  2977  			mh.Truncated = true
  2978  			remainSize = 0
  2979  			return
  2980  		}
  2981  		remainSize -= size
  2982  
  2983  		mh.Fields = append(mh.Fields, hf)
  2984  	})
  2985  	// Lose reference to MetaHeadersFrame:
  2986  	defer hdec.SetEmitFunc(func(hf hpack.HeaderField) {})
  2987  
  2988  	var hc http2headersOrContinuation = hf
  2989  	for {
  2990  		frag := hc.HeaderBlockFragment()
  2991  
  2992  		// Avoid parsing large amounts of headers that we will then discard.
  2993  		// If the sender exceeds the max header list size by too much,
  2994  		// skip parsing the fragment and close the connection.
  2995  		//
  2996  		// "Too much" is either any CONTINUATION frame after we've already
  2997  		// exceeded the max header list size (in which case remainSize is 0),
  2998  		// or a frame whose encoded size is more than twice the remaining
  2999  		// header list bytes we're willing to accept.
  3000  		if int64(len(frag)) > int64(2*remainSize) {
  3001  			if http2VerboseLogs {
  3002  				log.Printf("http2: header list too large")
  3003  			}
  3004  			// It would be nice to send a RST_STREAM before sending the GOAWAY,
  3005  			// but the structure of the server's frame writer makes this difficult.
  3006  			return mh, http2ConnectionError(http2ErrCodeProtocol)
  3007  		}
  3008  
  3009  		// Also close the connection after any CONTINUATION frame following an
  3010  		// invalid header, since we stop tracking the size of the headers after
  3011  		// an invalid one.
  3012  		if invalid != nil {
  3013  			if http2VerboseLogs {
  3014  				log.Printf("http2: invalid header: %v", invalid)
  3015  			}
  3016  			// It would be nice to send a RST_STREAM before sending the GOAWAY,
  3017  			// but the structure of the server's frame writer makes this difficult.
  3018  			return mh, http2ConnectionError(http2ErrCodeProtocol)
  3019  		}
  3020  
  3021  		if _, err := hdec.Write(frag); err != nil {
  3022  			return mh, http2ConnectionError(http2ErrCodeCompression)
  3023  		}
  3024  
  3025  		if hc.HeadersEnded() {
  3026  			break
  3027  		}
  3028  		if f, err := fr.ReadFrame(); err != nil {
  3029  			return nil, err
  3030  		} else {
  3031  			hc = f.(*http2ContinuationFrame) // guaranteed by checkFrameOrder
  3032  		}
  3033  	}
  3034  
  3035  	mh.http2HeadersFrame.headerFragBuf = nil
  3036  	mh.http2HeadersFrame.invalidate()
  3037  
  3038  	if err := hdec.Close(); err != nil {
  3039  		return mh, http2ConnectionError(http2ErrCodeCompression)
  3040  	}
  3041  	if invalid != nil {
  3042  		fr.errDetail = invalid
  3043  		if http2VerboseLogs {
  3044  			log.Printf("http2: invalid header: %v", invalid)
  3045  		}
  3046  		return nil, http2StreamError{mh.StreamID, http2ErrCodeProtocol, invalid}
  3047  	}
  3048  	if err := mh.checkPseudos(); err != nil {
  3049  		fr.errDetail = err
  3050  		if http2VerboseLogs {
  3051  			log.Printf("http2: invalid pseudo headers: %v", err)
  3052  		}
  3053  		return nil, http2StreamError{mh.StreamID, http2ErrCodeProtocol, err}
  3054  	}
  3055  	return mh, nil
  3056  }
  3057  
  3058  func http2summarizeFrame(f http2Frame) string {
  3059  	var buf bytes.Buffer
  3060  	f.Header().writeDebug(&buf)
  3061  	switch f := f.(type) {
  3062  	case *http2SettingsFrame:
  3063  		n := 0
  3064  		f.ForeachSetting(func(s http2Setting) error {
  3065  			n++
  3066  			if n == 1 {
  3067  				buf.WriteString(", settings:")
  3068  			}
  3069  			fmt.Fprintf(&buf, " %v=%v,", s.ID, s.Val)
  3070  			return nil
  3071  		})
  3072  		if n > 0 {
  3073  			buf.Truncate(buf.Len() - 1) // remove trailing comma
  3074  		}
  3075  	case *http2DataFrame:
  3076  		data := f.Data()
  3077  		const max = 256
  3078  		if len(data) > max {
  3079  			data = data[:max]
  3080  		}
  3081  		fmt.Fprintf(&buf, " data=%q", data)
  3082  		if len(f.Data()) > max {
  3083  			fmt.Fprintf(&buf, " (%d bytes omitted)", len(f.Data())-max)
  3084  		}
  3085  	case *http2WindowUpdateFrame:
  3086  		if f.StreamID == 0 {
  3087  			buf.WriteString(" (conn)")
  3088  		}
  3089  		fmt.Fprintf(&buf, " incr=%v", f.Increment)
  3090  	case *http2PingFrame:
  3091  		fmt.Fprintf(&buf, " ping=%q", f.Data[:])
  3092  	case *http2GoAwayFrame:
  3093  		fmt.Fprintf(&buf, " LastStreamID=%v ErrCode=%v Debug=%q",
  3094  			f.LastStreamID, f.ErrCode, f.debugData)
  3095  	case *http2RSTStreamFrame:
  3096  		fmt.Fprintf(&buf, " ErrCode=%v", f.ErrCode)
  3097  	}
  3098  	return buf.String()
  3099  }
  3100  
  3101  var http2DebugGoroutines = os.Getenv("DEBUG_HTTP2_GOROUTINES") == "1"
  3102  
  3103  type http2goroutineLock uint64
  3104  
  3105  func http2newGoroutineLock() http2goroutineLock {
  3106  	if !http2DebugGoroutines {
  3107  		return 0
  3108  	}
  3109  	return http2goroutineLock(http2curGoroutineID())
  3110  }
  3111  
  3112  func (g http2goroutineLock) check() {
  3113  	if !http2DebugGoroutines {
  3114  		return
  3115  	}
  3116  	if http2curGoroutineID() != uint64(g) {
  3117  		panic("running on the wrong goroutine")
  3118  	}
  3119  }
  3120  
  3121  func (g http2goroutineLock) checkNotOn() {
  3122  	if !http2DebugGoroutines {
  3123  		return
  3124  	}
  3125  	if http2curGoroutineID() == uint64(g) {
  3126  		panic("running on the wrong goroutine")
  3127  	}
  3128  }
  3129  
  3130  var http2goroutineSpace = []byte("goroutine ")
  3131  
  3132  func http2curGoroutineID() uint64 {
  3133  	bp := http2littleBuf.Get().(*[]byte)
  3134  	defer http2littleBuf.Put(bp)
  3135  	b := *bp
  3136  	b = b[:runtime.Stack(b, false)]
  3137  	// Parse the 4707 out of "goroutine 4707 ["
  3138  	b = bytes.TrimPrefix(b, http2goroutineSpace)
  3139  	i := bytes.IndexByte(b, ' ')
  3140  	if i < 0 {
  3141  		panic(fmt.Sprintf("No space found in %q", b))
  3142  	}
  3143  	b = b[:i]
  3144  	n, err := http2parseUintBytes(b, 10, 64)
  3145  	if err != nil {
  3146  		panic(fmt.Sprintf("Failed to parse goroutine ID out of %q: %v", b, err))
  3147  	}
  3148  	return n
  3149  }
  3150  
  3151  var http2littleBuf = sync.Pool{
  3152  	New: func() interface{} {
  3153  		buf := make([]byte, 64)
  3154  		return &buf
  3155  	},
  3156  }
  3157  
  3158  // parseUintBytes is like strconv.ParseUint, but using a []byte.
  3159  func http2parseUintBytes(s []byte, base int, bitSize int) (n uint64, err error) {
  3160  	var cutoff, maxVal uint64
  3161  
  3162  	if bitSize == 0 {
  3163  		bitSize = int(strconv.IntSize)
  3164  	}
  3165  
  3166  	s0 := s
  3167  	switch {
  3168  	case len(s) < 1:
  3169  		err = strconv.ErrSyntax
  3170  		goto Error
  3171  
  3172  	case 2 <= base && base <= 36:
  3173  		// valid base; nothing to do
  3174  
  3175  	case base == 0:
  3176  		// Look for octal, hex prefix.
  3177  		switch {
  3178  		case s[0] == '0' && len(s) > 1 && (s[1] == 'x' || s[1] == 'X'):
  3179  			base = 16
  3180  			s = s[2:]
  3181  			if len(s) < 1 {
  3182  				err = strconv.ErrSyntax
  3183  				goto Error
  3184  			}
  3185  		case s[0] == '0':
  3186  			base = 8
  3187  		default:
  3188  			base = 10
  3189  		}
  3190  
  3191  	default:
  3192  		err = errors.New("invalid base " + strconv.Itoa(base))
  3193  		goto Error
  3194  	}
  3195  
  3196  	n = 0
  3197  	cutoff = http2cutoff64(base)
  3198  	maxVal = 1<<uint(bitSize) - 1
  3199  
  3200  	for i := 0; i < len(s); i++ {
  3201  		var v byte
  3202  		d := s[i]
  3203  		switch {
  3204  		case '0' <= d && d <= '9':
  3205  			v = d - '0'
  3206  		case 'a' <= d && d <= 'z':
  3207  			v = d - 'a' + 10
  3208  		case 'A' <= d && d <= 'Z':
  3209  			v = d - 'A' + 10
  3210  		default:
  3211  			n = 0
  3212  			err = strconv.ErrSyntax
  3213  			goto Error
  3214  		}
  3215  		if int(v) >= base {
  3216  			n = 0
  3217  			err = strconv.ErrSyntax
  3218  			goto Error
  3219  		}
  3220  
  3221  		if n >= cutoff {
  3222  			// n*base overflows
  3223  			n = 1<<64 - 1
  3224  			err = strconv.ErrRange
  3225  			goto Error
  3226  		}
  3227  		n *= uint64(base)
  3228  
  3229  		n1 := n + uint64(v)
  3230  		if n1 < n || n1 > maxVal {
  3231  			// n+v overflows
  3232  			n = 1<<64 - 1
  3233  			err = strconv.ErrRange
  3234  			goto Error
  3235  		}
  3236  		n = n1
  3237  	}
  3238  
  3239  	return n, nil
  3240  
  3241  Error:
  3242  	return n, &strconv.NumError{Func: "ParseUint", Num: string(s0), Err: err}
  3243  }
  3244  
  3245  // Return the first number n such that n*base >= 1<<64.
  3246  func http2cutoff64(base int) uint64 {
  3247  	if base < 2 {
  3248  		return 0
  3249  	}
  3250  	return (1<<64-1)/uint64(base) + 1
  3251  }
  3252  
  3253  var (
  3254  	http2commonBuildOnce   sync.Once
  3255  	http2commonLowerHeader map[string]string // Go-Canonical-Case -> lower-case
  3256  	http2commonCanonHeader map[string]string // lower-case -> Go-Canonical-Case
  3257  )
  3258  
  3259  func http2buildCommonHeaderMapsOnce() {
  3260  	http2commonBuildOnce.Do(http2buildCommonHeaderMaps)
  3261  }
  3262  
  3263  func http2buildCommonHeaderMaps() {
  3264  	common := []string{
  3265  		"accept",
  3266  		"accept-charset",
  3267  		"accept-encoding",
  3268  		"accept-language",
  3269  		"accept-ranges",
  3270  		"age",
  3271  		"access-control-allow-credentials",
  3272  		"access-control-allow-headers",
  3273  		"access-control-allow-methods",
  3274  		"access-control-allow-origin",
  3275  		"access-control-expose-headers",
  3276  		"access-control-max-age",
  3277  		"access-control-request-headers",
  3278  		"access-control-request-method",
  3279  		"allow",
  3280  		"authorization",
  3281  		"cache-control",
  3282  		"content-disposition",
  3283  		"content-encoding",
  3284  		"content-language",
  3285  		"content-length",
  3286  		"content-location",
  3287  		"content-range",
  3288  		"content-type",
  3289  		"cookie",
  3290  		"date",
  3291  		"etag",
  3292  		"expect",
  3293  		"expires",
  3294  		"from",
  3295  		"host",
  3296  		"if-match",
  3297  		"if-modified-since",
  3298  		"if-none-match",
  3299  		"if-unmodified-since",
  3300  		"last-modified",
  3301  		"link",
  3302  		"location",
  3303  		"max-forwards",
  3304  		"origin",
  3305  		"proxy-authenticate",
  3306  		"proxy-authorization",
  3307  		"range",
  3308  		"referer",
  3309  		"refresh",
  3310  		"retry-after",
  3311  		"server",
  3312  		"set-cookie",
  3313  		"strict-transport-security",
  3314  		"trailer",
  3315  		"transfer-encoding",
  3316  		"user-agent",
  3317  		"vary",
  3318  		"via",
  3319  		"www-authenticate",
  3320  		"x-forwarded-for",
  3321  		"x-forwarded-proto",
  3322  	}
  3323  	http2commonLowerHeader = make(map[string]string, len(common))
  3324  	http2commonCanonHeader = make(map[string]string, len(common))
  3325  	for _, v := range common {
  3326  		chk := CanonicalHeaderKey(v)
  3327  		http2commonLowerHeader[chk] = v
  3328  		http2commonCanonHeader[v] = chk
  3329  	}
  3330  }
  3331  
  3332  func http2lowerHeader(v string) (lower string, ascii bool) {
  3333  	http2buildCommonHeaderMapsOnce()
  3334  	if s, ok := http2commonLowerHeader[v]; ok {
  3335  		return s, true
  3336  	}
  3337  	return http2asciiToLower(v)
  3338  }
  3339  
  3340  func http2canonicalHeader(v string) string {
  3341  	http2buildCommonHeaderMapsOnce()
  3342  	if s, ok := http2commonCanonHeader[v]; ok {
  3343  		return s
  3344  	}
  3345  	return CanonicalHeaderKey(v)
  3346  }
  3347  
  3348  var (
  3349  	http2VerboseLogs    bool
  3350  	http2logFrameWrites bool
  3351  	http2logFrameReads  bool
  3352  	http2inTests        bool
  3353  )
  3354  
  3355  func init() {
  3356  	e := os.Getenv("GODEBUG")
  3357  	if strings.Contains(e, "http2debug=1") {
  3358  		http2VerboseLogs = true
  3359  	}
  3360  	if strings.Contains(e, "http2debug=2") {
  3361  		http2VerboseLogs = true
  3362  		http2logFrameWrites = true
  3363  		http2logFrameReads = true
  3364  	}
  3365  }
  3366  
  3367  const (
  3368  	// ClientPreface is the string that must be sent by new
  3369  	// connections from clients.
  3370  	http2ClientPreface = "PRI * HTTP/2.0\r\n\r\nSM\r\n\r\n"
  3371  
  3372  	// SETTINGS_MAX_FRAME_SIZE default
  3373  	// https://httpwg.org/specs/rfc7540.html#rfc.section.6.5.2
  3374  	http2initialMaxFrameSize = 16384
  3375  
  3376  	// NextProtoTLS is the NPN/ALPN protocol negotiated during
  3377  	// HTTP/2's TLS setup.
  3378  	http2NextProtoTLS = "h2"
  3379  
  3380  	// https://httpwg.org/specs/rfc7540.html#SettingValues
  3381  	http2initialHeaderTableSize = 4096
  3382  
  3383  	http2initialWindowSize = 65535 // 6.9.2 Initial Flow Control Window Size
  3384  
  3385  	http2defaultMaxReadFrameSize = 1 << 20
  3386  )
  3387  
  3388  var (
  3389  	http2clientPreface = []byte(http2ClientPreface)
  3390  )
  3391  
  3392  type http2streamState int
  3393  
  3394  // HTTP/2 stream states.
  3395  //
  3396  // See http://tools.ietf.org/html/rfc7540#section-5.1.
  3397  //
  3398  // For simplicity, the server code merges "reserved (local)" into
  3399  // "half-closed (remote)". This is one less state transition to track.
  3400  // The only downside is that we send PUSH_PROMISEs slightly less
  3401  // liberally than allowable. More discussion here:
  3402  // https://lists.w3.org/Archives/Public/ietf-http-wg/2016JulSep/0599.html
  3403  //
  3404  // "reserved (remote)" is omitted since the client code does not
  3405  // support server push.
  3406  const (
  3407  	http2stateIdle http2streamState = iota
  3408  	http2stateOpen
  3409  	http2stateHalfClosedLocal
  3410  	http2stateHalfClosedRemote
  3411  	http2stateClosed
  3412  )
  3413  
  3414  var http2stateName = [...]string{
  3415  	http2stateIdle:             "Idle",
  3416  	http2stateOpen:             "Open",
  3417  	http2stateHalfClosedLocal:  "HalfClosedLocal",
  3418  	http2stateHalfClosedRemote: "HalfClosedRemote",
  3419  	http2stateClosed:           "Closed",
  3420  }
  3421  
  3422  func (st http2streamState) String() string {
  3423  	return http2stateName[st]
  3424  }
  3425  
  3426  // Setting is a setting parameter: which setting it is, and its value.
  3427  type http2Setting struct {
  3428  	// ID is which setting is being set.
  3429  	// See https://httpwg.org/specs/rfc7540.html#SettingFormat
  3430  	ID http2SettingID
  3431  
  3432  	// Val is the value.
  3433  	Val uint32
  3434  }
  3435  
  3436  func (s http2Setting) String() string {
  3437  	return fmt.Sprintf("[%v = %d]", s.ID, s.Val)
  3438  }
  3439  
  3440  // Valid reports whether the setting is valid.
  3441  func (s http2Setting) Valid() error {
  3442  	// Limits and error codes from 6.5.2 Defined SETTINGS Parameters
  3443  	switch s.ID {
  3444  	case http2SettingEnablePush:
  3445  		if s.Val != 1 && s.Val != 0 {
  3446  			return http2ConnectionError(http2ErrCodeProtocol)
  3447  		}
  3448  	case http2SettingInitialWindowSize:
  3449  		if s.Val > 1<<31-1 {
  3450  			return http2ConnectionError(http2ErrCodeFlowControl)
  3451  		}
  3452  	case http2SettingMaxFrameSize:
  3453  		if s.Val < 16384 || s.Val > 1<<24-1 {
  3454  			return http2ConnectionError(http2ErrCodeProtocol)
  3455  		}
  3456  	}
  3457  	return nil
  3458  }
  3459  
  3460  // A SettingID is an HTTP/2 setting as defined in
  3461  // https://httpwg.org/specs/rfc7540.html#iana-settings
  3462  type http2SettingID uint16
  3463  
  3464  const (
  3465  	http2SettingHeaderTableSize      http2SettingID = 0x1
  3466  	http2SettingEnablePush           http2SettingID = 0x2
  3467  	http2SettingMaxConcurrentStreams http2SettingID = 0x3
  3468  	http2SettingInitialWindowSize    http2SettingID = 0x4
  3469  	http2SettingMaxFrameSize         http2SettingID = 0x5
  3470  	http2SettingMaxHeaderListSize    http2SettingID = 0x6
  3471  )
  3472  
  3473  var http2settingName = map[http2SettingID]string{
  3474  	http2SettingHeaderTableSize:      "HEADER_TABLE_SIZE",
  3475  	http2SettingEnablePush:           "ENABLE_PUSH",
  3476  	http2SettingMaxConcurrentStreams: "MAX_CONCURRENT_STREAMS",
  3477  	http2SettingInitialWindowSize:    "INITIAL_WINDOW_SIZE",
  3478  	http2SettingMaxFrameSize:         "MAX_FRAME_SIZE",
  3479  	http2SettingMaxHeaderListSize:    "MAX_HEADER_LIST_SIZE",
  3480  }
  3481  
  3482  func (s http2SettingID) String() string {
  3483  	if v, ok := http2settingName[s]; ok {
  3484  		return v
  3485  	}
  3486  	return fmt.Sprintf("UNKNOWN_SETTING_%d", uint16(s))
  3487  }
  3488  
  3489  // validWireHeaderFieldName reports whether v is a valid header field
  3490  // name (key). See httpguts.ValidHeaderName for the base rules.
  3491  //
  3492  // Further, http2 says:
  3493  //
  3494  //	"Just as in HTTP/1.x, header field names are strings of ASCII
  3495  //	characters that are compared in a case-insensitive
  3496  //	fashion. However, header field names MUST be converted to
  3497  //	lowercase prior to their encoding in HTTP/2. "
  3498  func http2validWireHeaderFieldName(v string) bool {
  3499  	if len(v) == 0 {
  3500  		return false
  3501  	}
  3502  	for _, r := range v {
  3503  		if !httpguts.IsTokenRune(r) {
  3504  			return false
  3505  		}
  3506  		if 'A' <= r && r <= 'Z' {
  3507  			return false
  3508  		}
  3509  	}
  3510  	return true
  3511  }
  3512  
  3513  func http2httpCodeString(code int) string {
  3514  	switch code {
  3515  	case 200:
  3516  		return "200"
  3517  	case 404:
  3518  		return "404"
  3519  	}
  3520  	return strconv.Itoa(code)
  3521  }
  3522  
  3523  // from pkg io
  3524  type http2stringWriter interface {
  3525  	WriteString(s string) (n int, err error)
  3526  }
  3527  
  3528  // A closeWaiter is like a sync.WaitGroup but only goes 1 to 0 (open to closed).
  3529  type http2closeWaiter chan struct{}
  3530  
  3531  // Init makes a closeWaiter usable.
  3532  // It exists because so a closeWaiter value can be placed inside a
  3533  // larger struct and have the Mutex and Cond's memory in the same
  3534  // allocation.
  3535  func (cw *http2closeWaiter) Init() {
  3536  	*cw = make(chan struct{})
  3537  }
  3538  
  3539  // Close marks the closeWaiter as closed and unblocks any waiters.
  3540  func (cw http2closeWaiter) Close() {
  3541  	close(cw)
  3542  }
  3543  
  3544  // Wait waits for the closeWaiter to become closed.
  3545  func (cw http2closeWaiter) Wait() {
  3546  	<-cw
  3547  }
  3548  
  3549  // bufferedWriter is a buffered writer that writes to w.
  3550  // Its buffered writer is lazily allocated as needed, to minimize
  3551  // idle memory usage with many connections.
  3552  type http2bufferedWriter struct {
  3553  	_  http2incomparable
  3554  	w  io.Writer     // immutable
  3555  	bw *bufio.Writer // non-nil when data is buffered
  3556  }
  3557  
  3558  func http2newBufferedWriter(w io.Writer) *http2bufferedWriter {
  3559  	return &http2bufferedWriter{w: w}
  3560  }
  3561  
  3562  // bufWriterPoolBufferSize is the size of bufio.Writer's
  3563  // buffers created using bufWriterPool.
  3564  //
  3565  // TODO: pick a less arbitrary value? this is a bit under
  3566  // (3 x typical 1500 byte MTU) at least. Other than that,
  3567  // not much thought went into it.
  3568  const http2bufWriterPoolBufferSize = 4 << 10
  3569  
  3570  var http2bufWriterPool = sync.Pool{
  3571  	New: func() interface{} {
  3572  		return bufio.NewWriterSize(nil, http2bufWriterPoolBufferSize)
  3573  	},
  3574  }
  3575  
  3576  func (w *http2bufferedWriter) Available() int {
  3577  	if w.bw == nil {
  3578  		return http2bufWriterPoolBufferSize
  3579  	}
  3580  	return w.bw.Available()
  3581  }
  3582  
  3583  func (w *http2bufferedWriter) Write(p []byte) (n int, err error) {
  3584  	if w.bw == nil {
  3585  		bw := http2bufWriterPool.Get().(*bufio.Writer)
  3586  		bw.Reset(w.w)
  3587  		w.bw = bw
  3588  	}
  3589  	return w.bw.Write(p)
  3590  }
  3591  
  3592  func (w *http2bufferedWriter) Flush() error {
  3593  	bw := w.bw
  3594  	if bw == nil {
  3595  		return nil
  3596  	}
  3597  	err := bw.Flush()
  3598  	bw.Reset(nil)
  3599  	http2bufWriterPool.Put(bw)
  3600  	w.bw = nil
  3601  	return err
  3602  }
  3603  
  3604  func http2mustUint31(v int32) uint32 {
  3605  	if v < 0 || v > 2147483647 {
  3606  		panic("out of range")
  3607  	}
  3608  	return uint32(v)
  3609  }
  3610  
  3611  // bodyAllowedForStatus reports whether a given response status code
  3612  // permits a body. See RFC 7230, section 3.3.
  3613  func http2bodyAllowedForStatus(status int) bool {
  3614  	switch {
  3615  	case status >= 100 && status <= 199:
  3616  		return false
  3617  	case status == 204:
  3618  		return false
  3619  	case status == 304:
  3620  		return false
  3621  	}
  3622  	return true
  3623  }
  3624  
  3625  type http2httpError struct {
  3626  	_       http2incomparable
  3627  	msg     string
  3628  	timeout bool
  3629  }
  3630  
  3631  func (e *http2httpError) Error() string { return e.msg }
  3632  
  3633  func (e *http2httpError) Timeout() bool { return e.timeout }
  3634  
  3635  func (e *http2httpError) Temporary() bool { return true }
  3636  
  3637  var http2errTimeout error = &http2httpError{msg: "http2: timeout awaiting response headers", timeout: true}
  3638  
  3639  type http2connectionStater interface {
  3640  	ConnectionState() tls.ConnectionState
  3641  }
  3642  
  3643  var http2sorterPool = sync.Pool{New: func() interface{} { return new(http2sorter) }}
  3644  
  3645  type http2sorter struct {
  3646  	v []string // owned by sorter
  3647  }
  3648  
  3649  func (s *http2sorter) Len() int { return len(s.v) }
  3650  
  3651  func (s *http2sorter) Swap(i, j int) { s.v[i], s.v[j] = s.v[j], s.v[i] }
  3652  
  3653  func (s *http2sorter) Less(i, j int) bool { return s.v[i] < s.v[j] }
  3654  
  3655  // Keys returns the sorted keys of h.
  3656  //
  3657  // The returned slice is only valid until s used again or returned to
  3658  // its pool.
  3659  func (s *http2sorter) Keys(h Header) []string {
  3660  	keys := s.v[:0]
  3661  	for k := range h {
  3662  		keys = append(keys, k)
  3663  	}
  3664  	s.v = keys
  3665  	sort.Sort(s)
  3666  	return keys
  3667  }
  3668  
  3669  func (s *http2sorter) SortStrings(ss []string) {
  3670  	// Our sorter works on s.v, which sorter owns, so
  3671  	// stash it away while we sort the user's buffer.
  3672  	save := s.v
  3673  	s.v = ss
  3674  	sort.Sort(s)
  3675  	s.v = save
  3676  }
  3677  
  3678  // validPseudoPath reports whether v is a valid :path pseudo-header
  3679  // value. It must be either:
  3680  //
  3681  //   - a non-empty string starting with '/'
  3682  //   - the string '*', for OPTIONS requests.
  3683  //
  3684  // For now this is only used a quick check for deciding when to clean
  3685  // up Opaque URLs before sending requests from the Transport.
  3686  // See golang.org/issue/16847
  3687  //
  3688  // We used to enforce that the path also didn't start with "//", but
  3689  // Google's GFE accepts such paths and Chrome sends them, so ignore
  3690  // that part of the spec. See golang.org/issue/19103.
  3691  func http2validPseudoPath(v string) bool {
  3692  	return (len(v) > 0 && v[0] == '/') || v == "*"
  3693  }
  3694  
  3695  // incomparable is a zero-width, non-comparable type. Adding it to a struct
  3696  // makes that struct also non-comparable, and generally doesn't add
  3697  // any size (as long as it's first).
  3698  type http2incomparable [0]func()
  3699  
  3700  // synctestGroupInterface is the methods of synctestGroup used by Server and Transport.
  3701  // It's defined as an interface here to let us keep synctestGroup entirely test-only
  3702  // and not a part of non-test builds.
  3703  type http2synctestGroupInterface interface {
  3704  	Join()
  3705  	Now() time.Time
  3706  	NewTimer(d time.Duration) http2timer
  3707  	AfterFunc(d time.Duration, f func()) http2timer
  3708  	ContextWithTimeout(ctx context.Context, d time.Duration) (context.Context, context.CancelFunc)
  3709  }
  3710  
  3711  // pipe is a goroutine-safe io.Reader/io.Writer pair. It's like
  3712  // io.Pipe except there are no PipeReader/PipeWriter halves, and the
  3713  // underlying buffer is an interface. (io.Pipe is always unbuffered)
  3714  type http2pipe struct {
  3715  	mu       sync.Mutex
  3716  	c        sync.Cond       // c.L lazily initialized to &p.mu
  3717  	b        http2pipeBuffer // nil when done reading
  3718  	unread   int             // bytes unread when done
  3719  	err      error           // read error once empty. non-nil means closed.
  3720  	breakErr error           // immediate read error (caller doesn't see rest of b)
  3721  	donec    chan struct{}   // closed on error
  3722  	readFn   func()          // optional code to run in Read before error
  3723  }
  3724  
  3725  type http2pipeBuffer interface {
  3726  	Len() int
  3727  	io.Writer
  3728  	io.Reader
  3729  }
  3730  
  3731  // setBuffer initializes the pipe buffer.
  3732  // It has no effect if the pipe is already closed.
  3733  func (p *http2pipe) setBuffer(b http2pipeBuffer) {
  3734  	p.mu.Lock()
  3735  	defer p.mu.Unlock()
  3736  	if p.err != nil || p.breakErr != nil {
  3737  		return
  3738  	}
  3739  	p.b = b
  3740  }
  3741  
  3742  func (p *http2pipe) Len() int {
  3743  	p.mu.Lock()
  3744  	defer p.mu.Unlock()
  3745  	if p.b == nil {
  3746  		return p.unread
  3747  	}
  3748  	return p.b.Len()
  3749  }
  3750  
  3751  // Read waits until data is available and copies bytes
  3752  // from the buffer into p.
  3753  func (p *http2pipe) Read(d []byte) (n int, err error) {
  3754  	p.mu.Lock()
  3755  	defer p.mu.Unlock()
  3756  	if p.c.L == nil {
  3757  		p.c.L = &p.mu
  3758  	}
  3759  	for {
  3760  		if p.breakErr != nil {
  3761  			return 0, p.breakErr
  3762  		}
  3763  		if p.b != nil && p.b.Len() > 0 {
  3764  			return p.b.Read(d)
  3765  		}
  3766  		if p.err != nil {
  3767  			if p.readFn != nil {
  3768  				p.readFn()     // e.g. copy trailers
  3769  				p.readFn = nil // not sticky like p.err
  3770  			}
  3771  			p.b = nil
  3772  			return 0, p.err
  3773  		}
  3774  		p.c.Wait()
  3775  	}
  3776  }
  3777  
  3778  var (
  3779  	http2errClosedPipeWrite        = errors.New("write on closed buffer")
  3780  	http2errUninitializedPipeWrite = errors.New("write on uninitialized buffer")
  3781  )
  3782  
  3783  // Write copies bytes from p into the buffer and wakes a reader.
  3784  // It is an error to write more data than the buffer can hold.
  3785  func (p *http2pipe) Write(d []byte) (n int, err error) {
  3786  	p.mu.Lock()
  3787  	defer p.mu.Unlock()
  3788  	if p.c.L == nil {
  3789  		p.c.L = &p.mu
  3790  	}
  3791  	defer p.c.Signal()
  3792  	if p.err != nil || p.breakErr != nil {
  3793  		return 0, http2errClosedPipeWrite
  3794  	}
  3795  	// pipe.setBuffer is never invoked, leaving the buffer uninitialized.
  3796  	// We shouldn't try to write to an uninitialized pipe,
  3797  	// but returning an error is better than panicking.
  3798  	if p.b == nil {
  3799  		return 0, http2errUninitializedPipeWrite
  3800  	}
  3801  	return p.b.Write(d)
  3802  }
  3803  
  3804  // CloseWithError causes the next Read (waking up a current blocked
  3805  // Read if needed) to return the provided err after all data has been
  3806  // read.
  3807  //
  3808  // The error must be non-nil.
  3809  func (p *http2pipe) CloseWithError(err error) { p.closeWithError(&p.err, err, nil) }
  3810  
  3811  // BreakWithError causes the next Read (waking up a current blocked
  3812  // Read if needed) to return the provided err immediately, without
  3813  // waiting for unread data.
  3814  func (p *http2pipe) BreakWithError(err error) { p.closeWithError(&p.breakErr, err, nil) }
  3815  
  3816  // closeWithErrorAndCode is like CloseWithError but also sets some code to run
  3817  // in the caller's goroutine before returning the error.
  3818  func (p *http2pipe) closeWithErrorAndCode(err error, fn func()) { p.closeWithError(&p.err, err, fn) }
  3819  
  3820  func (p *http2pipe) closeWithError(dst *error, err error, fn func()) {
  3821  	if err == nil {
  3822  		panic("err must be non-nil")
  3823  	}
  3824  	p.mu.Lock()
  3825  	defer p.mu.Unlock()
  3826  	if p.c.L == nil {
  3827  		p.c.L = &p.mu
  3828  	}
  3829  	defer p.c.Signal()
  3830  	if *dst != nil {
  3831  		// Already been done.
  3832  		return
  3833  	}
  3834  	p.readFn = fn
  3835  	if dst == &p.breakErr {
  3836  		if p.b != nil {
  3837  			p.unread += p.b.Len()
  3838  		}
  3839  		p.b = nil
  3840  	}
  3841  	*dst = err
  3842  	p.closeDoneLocked()
  3843  }
  3844  
  3845  // requires p.mu be held.
  3846  func (p *http2pipe) closeDoneLocked() {
  3847  	if p.donec == nil {
  3848  		return
  3849  	}
  3850  	// Close if unclosed. This isn't racy since we always
  3851  	// hold p.mu while closing.
  3852  	select {
  3853  	case <-p.donec:
  3854  	default:
  3855  		close(p.donec)
  3856  	}
  3857  }
  3858  
  3859  // Err returns the error (if any) first set by BreakWithError or CloseWithError.
  3860  func (p *http2pipe) Err() error {
  3861  	p.mu.Lock()
  3862  	defer p.mu.Unlock()
  3863  	if p.breakErr != nil {
  3864  		return p.breakErr
  3865  	}
  3866  	return p.err
  3867  }
  3868  
  3869  // Done returns a channel which is closed if and when this pipe is closed
  3870  // with CloseWithError.
  3871  func (p *http2pipe) Done() <-chan struct{} {
  3872  	p.mu.Lock()
  3873  	defer p.mu.Unlock()
  3874  	if p.donec == nil {
  3875  		p.donec = make(chan struct{})
  3876  		if p.err != nil || p.breakErr != nil {
  3877  			// Already hit an error.
  3878  			p.closeDoneLocked()
  3879  		}
  3880  	}
  3881  	return p.donec
  3882  }
  3883  
  3884  const (
  3885  	http2prefaceTimeout         = 10 * time.Second
  3886  	http2firstSettingsTimeout   = 2 * time.Second // should be in-flight with preface anyway
  3887  	http2handlerChunkWriteSize  = 4 << 10
  3888  	http2defaultMaxStreams      = 250 // TODO: make this 100 as the GFE seems to?
  3889  	http2maxQueuedControlFrames = 10000
  3890  )
  3891  
  3892  var (
  3893  	http2errClientDisconnected = errors.New("client disconnected")
  3894  	http2errClosedBody         = errors.New("body closed by handler")
  3895  	http2errHandlerComplete    = errors.New("http2: request body closed due to handler exiting")
  3896  	http2errStreamClosed       = errors.New("http2: stream closed")
  3897  )
  3898  
  3899  var http2responseWriterStatePool = sync.Pool{
  3900  	New: func() interface{} {
  3901  		rws := &http2responseWriterState{}
  3902  		rws.bw = bufio.NewWriterSize(http2chunkWriter{rws}, http2handlerChunkWriteSize)
  3903  		return rws
  3904  	},
  3905  }
  3906  
  3907  // Test hooks.
  3908  var (
  3909  	http2testHookOnConn        func()
  3910  	http2testHookGetServerConn func(*http2serverConn)
  3911  	http2testHookOnPanicMu     *sync.Mutex // nil except in tests
  3912  	http2testHookOnPanic       func(sc *http2serverConn, panicVal interface{}) (rePanic bool)
  3913  )
  3914  
  3915  // Server is an HTTP/2 server.
  3916  type http2Server struct {
  3917  	// MaxHandlers limits the number of http.Handler ServeHTTP goroutines
  3918  	// which may run at a time over all connections.
  3919  	// Negative or zero no limit.
  3920  	// TODO: implement
  3921  	MaxHandlers int
  3922  
  3923  	// MaxConcurrentStreams optionally specifies the number of
  3924  	// concurrent streams that each client may have open at a
  3925  	// time. This is unrelated to the number of http.Handler goroutines
  3926  	// which may be active globally, which is MaxHandlers.
  3927  	// If zero, MaxConcurrentStreams defaults to at least 100, per
  3928  	// the HTTP/2 spec's recommendations.
  3929  	MaxConcurrentStreams uint32
  3930  
  3931  	// MaxDecoderHeaderTableSize optionally specifies the http2
  3932  	// SETTINGS_HEADER_TABLE_SIZE to send in the initial settings frame. It
  3933  	// informs the remote endpoint of the maximum size of the header compression
  3934  	// table used to decode header blocks, in octets. If zero, the default value
  3935  	// of 4096 is used.
  3936  	MaxDecoderHeaderTableSize uint32
  3937  
  3938  	// MaxEncoderHeaderTableSize optionally specifies an upper limit for the
  3939  	// header compression table used for encoding request headers. Received
  3940  	// SETTINGS_HEADER_TABLE_SIZE settings are capped at this limit. If zero,
  3941  	// the default value of 4096 is used.
  3942  	MaxEncoderHeaderTableSize uint32
  3943  
  3944  	// MaxReadFrameSize optionally specifies the largest frame
  3945  	// this server is willing to read. A valid value is between
  3946  	// 16k and 16M, inclusive. If zero or otherwise invalid, a
  3947  	// default value is used.
  3948  	MaxReadFrameSize uint32
  3949  
  3950  	// PermitProhibitedCipherSuites, if true, permits the use of
  3951  	// cipher suites prohibited by the HTTP/2 spec.
  3952  	PermitProhibitedCipherSuites bool
  3953  
  3954  	// IdleTimeout specifies how long until idle clients should be
  3955  	// closed with a GOAWAY frame. PING frames are not considered
  3956  	// activity for the purposes of IdleTimeout.
  3957  	// If zero or negative, there is no timeout.
  3958  	IdleTimeout time.Duration
  3959  
  3960  	// MaxUploadBufferPerConnection is the size of the initial flow
  3961  	// control window for each connections. The HTTP/2 spec does not
  3962  	// allow this to be smaller than 65535 or larger than 2^32-1.
  3963  	// If the value is outside this range, a default value will be
  3964  	// used instead.
  3965  	MaxUploadBufferPerConnection int32
  3966  
  3967  	// MaxUploadBufferPerStream is the size of the initial flow control
  3968  	// window for each stream. The HTTP/2 spec does not allow this to
  3969  	// be larger than 2^32-1. If the value is zero or larger than the
  3970  	// maximum, a default value will be used instead.
  3971  	MaxUploadBufferPerStream int32
  3972  
  3973  	// NewWriteScheduler constructs a write scheduler for a connection.
  3974  	// If nil, a default scheduler is chosen.
  3975  	NewWriteScheduler func() http2WriteScheduler
  3976  
  3977  	// CountError, if non-nil, is called on HTTP/2 server errors.
  3978  	// It's intended to increment a metric for monitoring, such
  3979  	// as an expvar or Prometheus metric.
  3980  	// The errType consists of only ASCII word characters.
  3981  	CountError func(errType string)
  3982  
  3983  	// Internal state. This is a pointer (rather than embedded directly)
  3984  	// so that we don't embed a Mutex in this struct, which will make the
  3985  	// struct non-copyable, which might break some callers.
  3986  	state *http2serverInternalState
  3987  
  3988  	// Synchronization group used for testing.
  3989  	// Outside of tests, this is nil.
  3990  	group http2synctestGroupInterface
  3991  }
  3992  
  3993  func (s *http2Server) markNewGoroutine() {
  3994  	if s.group != nil {
  3995  		s.group.Join()
  3996  	}
  3997  }
  3998  
  3999  func (s *http2Server) now() time.Time {
  4000  	if s.group != nil {
  4001  		return s.group.Now()
  4002  	}
  4003  	return time.Now()
  4004  }
  4005  
  4006  // newTimer creates a new time.Timer, or a synthetic timer in tests.
  4007  func (s *http2Server) newTimer(d time.Duration) http2timer {
  4008  	if s.group != nil {
  4009  		return s.group.NewTimer(d)
  4010  	}
  4011  	return http2timeTimer{time.NewTimer(d)}
  4012  }
  4013  
  4014  // afterFunc creates a new time.AfterFunc timer, or a synthetic timer in tests.
  4015  func (s *http2Server) afterFunc(d time.Duration, f func()) http2timer {
  4016  	if s.group != nil {
  4017  		return s.group.AfterFunc(d, f)
  4018  	}
  4019  	return http2timeTimer{time.AfterFunc(d, f)}
  4020  }
  4021  
  4022  func (s *http2Server) initialConnRecvWindowSize() int32 {
  4023  	if s.MaxUploadBufferPerConnection >= http2initialWindowSize {
  4024  		return s.MaxUploadBufferPerConnection
  4025  	}
  4026  	return 1 << 20
  4027  }
  4028  
  4029  func (s *http2Server) initialStreamRecvWindowSize() int32 {
  4030  	if s.MaxUploadBufferPerStream > 0 {
  4031  		return s.MaxUploadBufferPerStream
  4032  	}
  4033  	return 1 << 20
  4034  }
  4035  
  4036  func (s *http2Server) maxReadFrameSize() uint32 {
  4037  	if v := s.MaxReadFrameSize; v >= http2minMaxFrameSize && v <= http2maxFrameSize {
  4038  		return v
  4039  	}
  4040  	return http2defaultMaxReadFrameSize
  4041  }
  4042  
  4043  func (s *http2Server) maxConcurrentStreams() uint32 {
  4044  	if v := s.MaxConcurrentStreams; v > 0 {
  4045  		return v
  4046  	}
  4047  	return http2defaultMaxStreams
  4048  }
  4049  
  4050  func (s *http2Server) maxDecoderHeaderTableSize() uint32 {
  4051  	if v := s.MaxDecoderHeaderTableSize; v > 0 {
  4052  		return v
  4053  	}
  4054  	return http2initialHeaderTableSize
  4055  }
  4056  
  4057  func (s *http2Server) maxEncoderHeaderTableSize() uint32 {
  4058  	if v := s.MaxEncoderHeaderTableSize; v > 0 {
  4059  		return v
  4060  	}
  4061  	return http2initialHeaderTableSize
  4062  }
  4063  
  4064  // maxQueuedControlFrames is the maximum number of control frames like
  4065  // SETTINGS, PING and RST_STREAM that will be queued for writing before
  4066  // the connection is closed to prevent memory exhaustion attacks.
  4067  func (s *http2Server) maxQueuedControlFrames() int {
  4068  	// TODO: if anybody asks, add a Server field, and remember to define the
  4069  	// behavior of negative values.
  4070  	return http2maxQueuedControlFrames
  4071  }
  4072  
  4073  type http2serverInternalState struct {
  4074  	mu          sync.Mutex
  4075  	activeConns map[*http2serverConn]struct{}
  4076  }
  4077  
  4078  func (s *http2serverInternalState) registerConn(sc *http2serverConn) {
  4079  	if s == nil {
  4080  		return // if the Server was used without calling ConfigureServer
  4081  	}
  4082  	s.mu.Lock()
  4083  	s.activeConns[sc] = struct{}{}
  4084  	s.mu.Unlock()
  4085  }
  4086  
  4087  func (s *http2serverInternalState) unregisterConn(sc *http2serverConn) {
  4088  	if s == nil {
  4089  		return // if the Server was used without calling ConfigureServer
  4090  	}
  4091  	s.mu.Lock()
  4092  	delete(s.activeConns, sc)
  4093  	s.mu.Unlock()
  4094  }
  4095  
  4096  func (s *http2serverInternalState) startGracefulShutdown() {
  4097  	if s == nil {
  4098  		return // if the Server was used without calling ConfigureServer
  4099  	}
  4100  	s.mu.Lock()
  4101  	for sc := range s.activeConns {
  4102  		sc.startGracefulShutdown()
  4103  	}
  4104  	s.mu.Unlock()
  4105  }
  4106  
  4107  // ConfigureServer adds HTTP/2 support to a net/http Server.
  4108  //
  4109  // The configuration conf may be nil.
  4110  //
  4111  // ConfigureServer must be called before s begins serving.
  4112  func http2ConfigureServer(s *Server, conf *http2Server) error {
  4113  	if s == nil {
  4114  		panic("nil *http.Server")
  4115  	}
  4116  	if conf == nil {
  4117  		conf = new(http2Server)
  4118  	}
  4119  	conf.state = &http2serverInternalState{activeConns: make(map[*http2serverConn]struct{})}
  4120  	if h1, h2 := s, conf; h2.IdleTimeout == 0 {
  4121  		if h1.IdleTimeout != 0 {
  4122  			h2.IdleTimeout = h1.IdleTimeout
  4123  		} else {
  4124  			h2.IdleTimeout = h1.ReadTimeout
  4125  		}
  4126  	}
  4127  	s.RegisterOnShutdown(conf.state.startGracefulShutdown)
  4128  
  4129  	if s.TLSConfig == nil {
  4130  		s.TLSConfig = new(tls.Config)
  4131  	} else if s.TLSConfig.CipherSuites != nil && s.TLSConfig.MinVersion < tls.VersionTLS13 {
  4132  		// If they already provided a TLS 1.0–1.2 CipherSuite list, return an
  4133  		// error if it is missing ECDHE_RSA_WITH_AES_128_GCM_SHA256 or
  4134  		// ECDHE_ECDSA_WITH_AES_128_GCM_SHA256.
  4135  		haveRequired := false
  4136  		for _, cs := range s.TLSConfig.CipherSuites {
  4137  			switch cs {
  4138  			case tls.TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256,
  4139  				// Alternative MTI cipher to not discourage ECDSA-only servers.
  4140  				// See http://golang.org/cl/30721 for further information.
  4141  				tls.TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256:
  4142  				haveRequired = true
  4143  			}
  4144  		}
  4145  		if !haveRequired {
  4146  			return fmt.Errorf("http2: TLSConfig.CipherSuites is missing an HTTP/2-required AES_128_GCM_SHA256 cipher (need at least one of TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 or TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256)")
  4147  		}
  4148  	}
  4149  
  4150  	// Note: not setting MinVersion to tls.VersionTLS12,
  4151  	// as we don't want to interfere with HTTP/1.1 traffic
  4152  	// on the user's server. We enforce TLS 1.2 later once
  4153  	// we accept a connection. Ideally this should be done
  4154  	// during next-proto selection, but using TLS <1.2 with
  4155  	// HTTP/2 is still the client's bug.
  4156  
  4157  	s.TLSConfig.PreferServerCipherSuites = true
  4158  
  4159  	if !http2strSliceContains(s.TLSConfig.NextProtos, http2NextProtoTLS) {
  4160  		s.TLSConfig.NextProtos = append(s.TLSConfig.NextProtos, http2NextProtoTLS)
  4161  	}
  4162  	if !http2strSliceContains(s.TLSConfig.NextProtos, "http/1.1") {
  4163  		s.TLSConfig.NextProtos = append(s.TLSConfig.NextProtos, "http/1.1")
  4164  	}
  4165  
  4166  	if s.TLSNextProto == nil {
  4167  		s.TLSNextProto = map[string]func(*Server, *tls.Conn, Handler){}
  4168  	}
  4169  	protoHandler := func(hs *Server, c *tls.Conn, h Handler) {
  4170  		if http2testHookOnConn != nil {
  4171  			http2testHookOnConn()
  4172  		}
  4173  		// The TLSNextProto interface predates contexts, so
  4174  		// the net/http package passes down its per-connection
  4175  		// base context via an exported but unadvertised
  4176  		// method on the Handler. This is for internal
  4177  		// net/http<=>http2 use only.
  4178  		var ctx context.Context
  4179  		type baseContexter interface {
  4180  			BaseContext() context.Context
  4181  		}
  4182  		if bc, ok := h.(baseContexter); ok {
  4183  			ctx = bc.BaseContext()
  4184  		}
  4185  		conf.ServeConn(c, &http2ServeConnOpts{
  4186  			Context:    ctx,
  4187  			Handler:    h,
  4188  			BaseConfig: hs,
  4189  		})
  4190  	}
  4191  	s.TLSNextProto[http2NextProtoTLS] = protoHandler
  4192  	return nil
  4193  }
  4194  
  4195  // ServeConnOpts are options for the Server.ServeConn method.
  4196  type http2ServeConnOpts struct {
  4197  	// Context is the base context to use.
  4198  	// If nil, context.Background is used.
  4199  	Context context.Context
  4200  
  4201  	// BaseConfig optionally sets the base configuration
  4202  	// for values. If nil, defaults are used.
  4203  	BaseConfig *Server
  4204  
  4205  	// Handler specifies which handler to use for processing
  4206  	// requests. If nil, BaseConfig.Handler is used. If BaseConfig
  4207  	// or BaseConfig.Handler is nil, http.DefaultServeMux is used.
  4208  	Handler Handler
  4209  
  4210  	// UpgradeRequest is an initial request received on a connection
  4211  	// undergoing an h2c upgrade. The request body must have been
  4212  	// completely read from the connection before calling ServeConn,
  4213  	// and the 101 Switching Protocols response written.
  4214  	UpgradeRequest *Request
  4215  
  4216  	// Settings is the decoded contents of the HTTP2-Settings header
  4217  	// in an h2c upgrade request.
  4218  	Settings []byte
  4219  
  4220  	// SawClientPreface is set if the HTTP/2 connection preface
  4221  	// has already been read from the connection.
  4222  	SawClientPreface bool
  4223  }
  4224  
  4225  func (o *http2ServeConnOpts) context() context.Context {
  4226  	if o != nil && o.Context != nil {
  4227  		return o.Context
  4228  	}
  4229  	return context.Background()
  4230  }
  4231  
  4232  func (o *http2ServeConnOpts) baseConfig() *Server {
  4233  	if o != nil && o.BaseConfig != nil {
  4234  		return o.BaseConfig
  4235  	}
  4236  	return new(Server)
  4237  }
  4238  
  4239  func (o *http2ServeConnOpts) handler() Handler {
  4240  	if o != nil {
  4241  		if o.Handler != nil {
  4242  			return o.Handler
  4243  		}
  4244  		if o.BaseConfig != nil && o.BaseConfig.Handler != nil {
  4245  			return o.BaseConfig.Handler
  4246  		}
  4247  	}
  4248  	return DefaultServeMux
  4249  }
  4250  
  4251  // ServeConn serves HTTP/2 requests on the provided connection and
  4252  // blocks until the connection is no longer readable.
  4253  //
  4254  // ServeConn starts speaking HTTP/2 assuming that c has not had any
  4255  // reads or writes. It writes its initial settings frame and expects
  4256  // to be able to read the preface and settings frame from the
  4257  // client. If c has a ConnectionState method like a *tls.Conn, the
  4258  // ConnectionState is used to verify the TLS ciphersuite and to set
  4259  // the Request.TLS field in Handlers.
  4260  //
  4261  // ServeConn does not support h2c by itself. Any h2c support must be
  4262  // implemented in terms of providing a suitably-behaving net.Conn.
  4263  //
  4264  // The opts parameter is optional. If nil, default values are used.
  4265  func (s *http2Server) ServeConn(c net.Conn, opts *http2ServeConnOpts) {
  4266  	s.serveConn(c, opts, nil)
  4267  }
  4268  
  4269  func (s *http2Server) serveConn(c net.Conn, opts *http2ServeConnOpts, newf func(*http2serverConn)) {
  4270  	baseCtx, cancel := http2serverConnBaseContext(c, opts)
  4271  	defer cancel()
  4272  
  4273  	sc := &http2serverConn{
  4274  		srv:                         s,
  4275  		hs:                          opts.baseConfig(),
  4276  		conn:                        c,
  4277  		baseCtx:                     baseCtx,
  4278  		remoteAddrStr:               c.RemoteAddr().String(),
  4279  		bw:                          http2newBufferedWriter(c),
  4280  		handler:                     opts.handler(),
  4281  		streams:                     make(map[uint32]*http2stream),
  4282  		readFrameCh:                 make(chan http2readFrameResult),
  4283  		wantWriteFrameCh:            make(chan http2FrameWriteRequest, 8),
  4284  		serveMsgCh:                  make(chan interface{}, 8),
  4285  		wroteFrameCh:                make(chan http2frameWriteResult, 1), // buffered; one send in writeFrameAsync
  4286  		bodyReadCh:                  make(chan http2bodyReadMsg),         // buffering doesn't matter either way
  4287  		doneServing:                 make(chan struct{}),
  4288  		clientMaxStreams:            math.MaxUint32, // Section 6.5.2: "Initially, there is no limit to this value"
  4289  		advMaxStreams:               s.maxConcurrentStreams(),
  4290  		initialStreamSendWindowSize: http2initialWindowSize,
  4291  		maxFrameSize:                http2initialMaxFrameSize,
  4292  		serveG:                      http2newGoroutineLock(),
  4293  		pushEnabled:                 true,
  4294  		sawClientPreface:            opts.SawClientPreface,
  4295  	}
  4296  	if newf != nil {
  4297  		newf(sc)
  4298  	}
  4299  
  4300  	s.state.registerConn(sc)
  4301  	defer s.state.unregisterConn(sc)
  4302  
  4303  	// The net/http package sets the write deadline from the
  4304  	// http.Server.WriteTimeout during the TLS handshake, but then
  4305  	// passes the connection off to us with the deadline already set.
  4306  	// Write deadlines are set per stream in serverConn.newStream.
  4307  	// Disarm the net.Conn write deadline here.
  4308  	if sc.hs.WriteTimeout > 0 {
  4309  		sc.conn.SetWriteDeadline(time.Time{})
  4310  	}
  4311  
  4312  	if s.NewWriteScheduler != nil {
  4313  		sc.writeSched = s.NewWriteScheduler()
  4314  	} else {
  4315  		sc.writeSched = http2newRoundRobinWriteScheduler()
  4316  	}
  4317  
  4318  	// These start at the RFC-specified defaults. If there is a higher
  4319  	// configured value for inflow, that will be updated when we send a
  4320  	// WINDOW_UPDATE shortly after sending SETTINGS.
  4321  	sc.flow.add(http2initialWindowSize)
  4322  	sc.inflow.init(http2initialWindowSize)
  4323  	sc.hpackEncoder = hpack.NewEncoder(&sc.headerWriteBuf)
  4324  	sc.hpackEncoder.SetMaxDynamicTableSizeLimit(s.maxEncoderHeaderTableSize())
  4325  
  4326  	fr := http2NewFramer(sc.bw, c)
  4327  	if s.CountError != nil {
  4328  		fr.countError = s.CountError
  4329  	}
  4330  	fr.ReadMetaHeaders = hpack.NewDecoder(s.maxDecoderHeaderTableSize(), nil)
  4331  	fr.MaxHeaderListSize = sc.maxHeaderListSize()
  4332  	fr.SetMaxReadFrameSize(s.maxReadFrameSize())
  4333  	sc.framer = fr
  4334  
  4335  	if tc, ok := c.(http2connectionStater); ok {
  4336  		sc.tlsState = new(tls.ConnectionState)
  4337  		*sc.tlsState = tc.ConnectionState()
  4338  		// 9.2 Use of TLS Features
  4339  		// An implementation of HTTP/2 over TLS MUST use TLS
  4340  		// 1.2 or higher with the restrictions on feature set
  4341  		// and cipher suite described in this section. Due to
  4342  		// implementation limitations, it might not be
  4343  		// possible to fail TLS negotiation. An endpoint MUST
  4344  		// immediately terminate an HTTP/2 connection that
  4345  		// does not meet the TLS requirements described in
  4346  		// this section with a connection error (Section
  4347  		// 5.4.1) of type INADEQUATE_SECURITY.
  4348  		if sc.tlsState.Version < tls.VersionTLS12 {
  4349  			sc.rejectConn(http2ErrCodeInadequateSecurity, "TLS version too low")
  4350  			return
  4351  		}
  4352  
  4353  		if sc.tlsState.ServerName == "" {
  4354  			// Client must use SNI, but we don't enforce that anymore,
  4355  			// since it was causing problems when connecting to bare IP
  4356  			// addresses during development.
  4357  			//
  4358  			// TODO: optionally enforce? Or enforce at the time we receive
  4359  			// a new request, and verify the ServerName matches the :authority?
  4360  			// But that precludes proxy situations, perhaps.
  4361  			//
  4362  			// So for now, do nothing here again.
  4363  		}
  4364  
  4365  		if !s.PermitProhibitedCipherSuites && http2isBadCipher(sc.tlsState.CipherSuite) {
  4366  			// "Endpoints MAY choose to generate a connection error
  4367  			// (Section 5.4.1) of type INADEQUATE_SECURITY if one of
  4368  			// the prohibited cipher suites are negotiated."
  4369  			//
  4370  			// We choose that. In my opinion, the spec is weak
  4371  			// here. It also says both parties must support at least
  4372  			// TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 so there's no
  4373  			// excuses here. If we really must, we could allow an
  4374  			// "AllowInsecureWeakCiphers" option on the server later.
  4375  			// Let's see how it plays out first.
  4376  			sc.rejectConn(http2ErrCodeInadequateSecurity, fmt.Sprintf("Prohibited TLS 1.2 Cipher Suite: %x", sc.tlsState.CipherSuite))
  4377  			return
  4378  		}
  4379  	}
  4380  
  4381  	if opts.Settings != nil {
  4382  		fr := &http2SettingsFrame{
  4383  			http2FrameHeader: http2FrameHeader{valid: true},
  4384  			p:                opts.Settings,
  4385  		}
  4386  		if err := fr.ForeachSetting(sc.processSetting); err != nil {
  4387  			sc.rejectConn(http2ErrCodeProtocol, "invalid settings")
  4388  			return
  4389  		}
  4390  		opts.Settings = nil
  4391  	}
  4392  
  4393  	if hook := http2testHookGetServerConn; hook != nil {
  4394  		hook(sc)
  4395  	}
  4396  
  4397  	if opts.UpgradeRequest != nil {
  4398  		sc.upgradeRequest(opts.UpgradeRequest)
  4399  		opts.UpgradeRequest = nil
  4400  	}
  4401  
  4402  	sc.serve()
  4403  }
  4404  
  4405  func http2serverConnBaseContext(c net.Conn, opts *http2ServeConnOpts) (ctx context.Context, cancel func()) {
  4406  	ctx, cancel = context.WithCancel(opts.context())
  4407  	ctx = context.WithValue(ctx, LocalAddrContextKey, c.LocalAddr())
  4408  	if hs := opts.baseConfig(); hs != nil {
  4409  		ctx = context.WithValue(ctx, ServerContextKey, hs)
  4410  	}
  4411  	return
  4412  }
  4413  
  4414  func (sc *http2serverConn) rejectConn(err http2ErrCode, debug string) {
  4415  	sc.vlogf("http2: server rejecting conn: %v, %s", err, debug)
  4416  	// ignoring errors. hanging up anyway.
  4417  	sc.framer.WriteGoAway(0, err, []byte(debug))
  4418  	sc.bw.Flush()
  4419  	sc.conn.Close()
  4420  }
  4421  
  4422  type http2serverConn struct {
  4423  	// Immutable:
  4424  	srv              *http2Server
  4425  	hs               *Server
  4426  	conn             net.Conn
  4427  	bw               *http2bufferedWriter // writing to conn
  4428  	handler          Handler
  4429  	baseCtx          context.Context
  4430  	framer           *http2Framer
  4431  	doneServing      chan struct{}               // closed when serverConn.serve ends
  4432  	readFrameCh      chan http2readFrameResult   // written by serverConn.readFrames
  4433  	wantWriteFrameCh chan http2FrameWriteRequest // from handlers -> serve
  4434  	wroteFrameCh     chan http2frameWriteResult  // from writeFrameAsync -> serve, tickles more frame writes
  4435  	bodyReadCh       chan http2bodyReadMsg       // from handlers -> serve
  4436  	serveMsgCh       chan interface{}            // misc messages & code to send to / run on the serve loop
  4437  	flow             http2outflow                // conn-wide (not stream-specific) outbound flow control
  4438  	inflow           http2inflow                 // conn-wide inbound flow control
  4439  	tlsState         *tls.ConnectionState        // shared by all handlers, like net/http
  4440  	remoteAddrStr    string
  4441  	writeSched       http2WriteScheduler
  4442  
  4443  	// Everything following is owned by the serve loop; use serveG.check():
  4444  	serveG                      http2goroutineLock // used to verify funcs are on serve()
  4445  	pushEnabled                 bool
  4446  	sawClientPreface            bool // preface has already been read, used in h2c upgrade
  4447  	sawFirstSettings            bool // got the initial SETTINGS frame after the preface
  4448  	needToSendSettingsAck       bool
  4449  	unackedSettings             int    // how many SETTINGS have we sent without ACKs?
  4450  	queuedControlFrames         int    // control frames in the writeSched queue
  4451  	clientMaxStreams            uint32 // SETTINGS_MAX_CONCURRENT_STREAMS from client (our PUSH_PROMISE limit)
  4452  	advMaxStreams               uint32 // our SETTINGS_MAX_CONCURRENT_STREAMS advertised the client
  4453  	curClientStreams            uint32 // number of open streams initiated by the client
  4454  	curPushedStreams            uint32 // number of open streams initiated by server push
  4455  	curHandlers                 uint32 // number of running handler goroutines
  4456  	maxClientStreamID           uint32 // max ever seen from client (odd), or 0 if there have been no client requests
  4457  	maxPushPromiseID            uint32 // ID of the last push promise (even), or 0 if there have been no pushes
  4458  	streams                     map[uint32]*http2stream
  4459  	unstartedHandlers           []http2unstartedHandler
  4460  	initialStreamSendWindowSize int32
  4461  	maxFrameSize                int32
  4462  	peerMaxHeaderListSize       uint32            // zero means unknown (default)
  4463  	canonHeader                 map[string]string // http2-lower-case -> Go-Canonical-Case
  4464  	canonHeaderKeysSize         int               // canonHeader keys size in bytes
  4465  	writingFrame                bool              // started writing a frame (on serve goroutine or separate)
  4466  	writingFrameAsync           bool              // started a frame on its own goroutine but haven't heard back on wroteFrameCh
  4467  	needsFrameFlush             bool              // last frame write wasn't a flush
  4468  	inGoAway                    bool              // we've started to or sent GOAWAY
  4469  	inFrameScheduleLoop         bool              // whether we're in the scheduleFrameWrite loop
  4470  	needToSendGoAway            bool              // we need to schedule a GOAWAY frame write
  4471  	goAwayCode                  http2ErrCode
  4472  	shutdownTimer               http2timer // nil until used
  4473  	idleTimer                   http2timer // nil if unused
  4474  
  4475  	// Owned by the writeFrameAsync goroutine:
  4476  	headerWriteBuf bytes.Buffer
  4477  	hpackEncoder   *hpack.Encoder
  4478  
  4479  	// Used by startGracefulShutdown.
  4480  	shutdownOnce sync.Once
  4481  }
  4482  
  4483  func (sc *http2serverConn) maxHeaderListSize() uint32 {
  4484  	n := sc.hs.MaxHeaderBytes
  4485  	if n <= 0 {
  4486  		n = DefaultMaxHeaderBytes
  4487  	}
  4488  	// http2's count is in a slightly different unit and includes 32 bytes per pair.
  4489  	// So, take the net/http.Server value and pad it up a bit, assuming 10 headers.
  4490  	const perFieldOverhead = 32 // per http2 spec
  4491  	const typicalHeaders = 10   // conservative
  4492  	return uint32(n + typicalHeaders*perFieldOverhead)
  4493  }
  4494  
  4495  func (sc *http2serverConn) curOpenStreams() uint32 {
  4496  	sc.serveG.check()
  4497  	return sc.curClientStreams + sc.curPushedStreams
  4498  }
  4499  
  4500  // stream represents a stream. This is the minimal metadata needed by
  4501  // the serve goroutine. Most of the actual stream state is owned by
  4502  // the http.Handler's goroutine in the responseWriter. Because the
  4503  // responseWriter's responseWriterState is recycled at the end of a
  4504  // handler, this struct intentionally has no pointer to the
  4505  // *responseWriter{,State} itself, as the Handler ending nils out the
  4506  // responseWriter's state field.
  4507  type http2stream struct {
  4508  	// immutable:
  4509  	sc        *http2serverConn
  4510  	id        uint32
  4511  	body      *http2pipe       // non-nil if expecting DATA frames
  4512  	cw        http2closeWaiter // closed wait stream transitions to closed state
  4513  	ctx       context.Context
  4514  	cancelCtx func()
  4515  
  4516  	// owned by serverConn's serve loop:
  4517  	bodyBytes        int64        // body bytes seen so far
  4518  	declBodyBytes    int64        // or -1 if undeclared
  4519  	flow             http2outflow // limits writing from Handler to client
  4520  	inflow           http2inflow  // what the client is allowed to POST/etc to us
  4521  	state            http2streamState
  4522  	resetQueued      bool       // RST_STREAM queued for write; set by sc.resetStream
  4523  	gotTrailerHeader bool       // HEADER frame for trailers was seen
  4524  	wroteHeaders     bool       // whether we wrote headers (not status 100)
  4525  	readDeadline     http2timer // nil if unused
  4526  	writeDeadline    http2timer // nil if unused
  4527  	closeErr         error      // set before cw is closed
  4528  
  4529  	trailer    Header // accumulated trailers
  4530  	reqTrailer Header // handler's Request.Trailer
  4531  }
  4532  
  4533  func (sc *http2serverConn) Framer() *http2Framer { return sc.framer }
  4534  
  4535  func (sc *http2serverConn) CloseConn() error { return sc.conn.Close() }
  4536  
  4537  func (sc *http2serverConn) Flush() error { return sc.bw.Flush() }
  4538  
  4539  func (sc *http2serverConn) HeaderEncoder() (*hpack.Encoder, *bytes.Buffer) {
  4540  	return sc.hpackEncoder, &sc.headerWriteBuf
  4541  }
  4542  
  4543  func (sc *http2serverConn) state(streamID uint32) (http2streamState, *http2stream) {
  4544  	sc.serveG.check()
  4545  	// http://tools.ietf.org/html/rfc7540#section-5.1
  4546  	if st, ok := sc.streams[streamID]; ok {
  4547  		return st.state, st
  4548  	}
  4549  	// "The first use of a new stream identifier implicitly closes all
  4550  	// streams in the "idle" state that might have been initiated by
  4551  	// that peer with a lower-valued stream identifier. For example, if
  4552  	// a client sends a HEADERS frame on stream 7 without ever sending a
  4553  	// frame on stream 5, then stream 5 transitions to the "closed"
  4554  	// state when the first frame for stream 7 is sent or received."
  4555  	if streamID%2 == 1 {
  4556  		if streamID <= sc.maxClientStreamID {
  4557  			return http2stateClosed, nil
  4558  		}
  4559  	} else {
  4560  		if streamID <= sc.maxPushPromiseID {
  4561  			return http2stateClosed, nil
  4562  		}
  4563  	}
  4564  	return http2stateIdle, nil
  4565  }
  4566  
  4567  // setConnState calls the net/http ConnState hook for this connection, if configured.
  4568  // Note that the net/http package does StateNew and StateClosed for us.
  4569  // There is currently no plan for StateHijacked or hijacking HTTP/2 connections.
  4570  func (sc *http2serverConn) setConnState(state ConnState) {
  4571  	if sc.hs.ConnState != nil {
  4572  		sc.hs.ConnState(sc.conn, state)
  4573  	}
  4574  }
  4575  
  4576  func (sc *http2serverConn) vlogf(format string, args ...interface{}) {
  4577  	if http2VerboseLogs {
  4578  		sc.logf(format, args...)
  4579  	}
  4580  }
  4581  
  4582  func (sc *http2serverConn) logf(format string, args ...interface{}) {
  4583  	if lg := sc.hs.ErrorLog; lg != nil {
  4584  		lg.Printf(format, args...)
  4585  	} else {
  4586  		log.Printf(format, args...)
  4587  	}
  4588  }
  4589  
  4590  // errno returns v's underlying uintptr, else 0.
  4591  //
  4592  // TODO: remove this helper function once http2 can use build
  4593  // tags. See comment in isClosedConnError.
  4594  func http2errno(v error) uintptr {
  4595  	if rv := reflect.ValueOf(v); rv.Kind() == reflect.Uintptr {
  4596  		return uintptr(rv.Uint())
  4597  	}
  4598  	return 0
  4599  }
  4600  
  4601  // isClosedConnError reports whether err is an error from use of a closed
  4602  // network connection.
  4603  func http2isClosedConnError(err error) bool {
  4604  	if err == nil {
  4605  		return false
  4606  	}
  4607  
  4608  	if errors.Is(err, net.ErrClosed) {
  4609  		return true
  4610  	}
  4611  
  4612  	// TODO(bradfitz): x/tools/cmd/bundle doesn't really support
  4613  	// build tags, so I can't make an http2_windows.go file with
  4614  	// Windows-specific stuff. Fix that and move this, once we
  4615  	// have a way to bundle this into std's net/http somehow.
  4616  	if runtime.GOOS == "windows" {
  4617  		if oe, ok := err.(*net.OpError); ok && oe.Op == "read" {
  4618  			if se, ok := oe.Err.(*os.SyscallError); ok && se.Syscall == "wsarecv" {
  4619  				const WSAECONNABORTED = 10053
  4620  				const WSAECONNRESET = 10054
  4621  				if n := http2errno(se.Err); n == WSAECONNRESET || n == WSAECONNABORTED {
  4622  					return true
  4623  				}
  4624  			}
  4625  		}
  4626  	}
  4627  	return false
  4628  }
  4629  
  4630  func (sc *http2serverConn) condlogf(err error, format string, args ...interface{}) {
  4631  	if err == nil {
  4632  		return
  4633  	}
  4634  	if err == io.EOF || err == io.ErrUnexpectedEOF || http2isClosedConnError(err) || err == http2errPrefaceTimeout {
  4635  		// Boring, expected errors.
  4636  		sc.vlogf(format, args...)
  4637  	} else {
  4638  		sc.logf(format, args...)
  4639  	}
  4640  }
  4641  
  4642  // maxCachedCanonicalHeadersKeysSize is an arbitrarily-chosen limit on the size
  4643  // of the entries in the canonHeader cache.
  4644  // This should be larger than the size of unique, uncommon header keys likely to
  4645  // be sent by the peer, while not so high as to permit unreasonable memory usage
  4646  // if the peer sends an unbounded number of unique header keys.
  4647  const http2maxCachedCanonicalHeadersKeysSize = 2048
  4648  
  4649  func (sc *http2serverConn) canonicalHeader(v string) string {
  4650  	sc.serveG.check()
  4651  	http2buildCommonHeaderMapsOnce()
  4652  	cv, ok := http2commonCanonHeader[v]
  4653  	if ok {
  4654  		return cv
  4655  	}
  4656  	cv, ok = sc.canonHeader[v]
  4657  	if ok {
  4658  		return cv
  4659  	}
  4660  	if sc.canonHeader == nil {
  4661  		sc.canonHeader = make(map[string]string)
  4662  	}
  4663  	cv = CanonicalHeaderKey(v)
  4664  	size := 100 + len(v)*2 // 100 bytes of map overhead + key + value
  4665  	if sc.canonHeaderKeysSize+size <= http2maxCachedCanonicalHeadersKeysSize {
  4666  		sc.canonHeader[v] = cv
  4667  		sc.canonHeaderKeysSize += size
  4668  	}
  4669  	return cv
  4670  }
  4671  
  4672  type http2readFrameResult struct {
  4673  	f   http2Frame // valid until readMore is called
  4674  	err error
  4675  
  4676  	// readMore should be called once the consumer no longer needs or
  4677  	// retains f. After readMore, f is invalid and more frames can be
  4678  	// read.
  4679  	readMore func()
  4680  }
  4681  
  4682  // readFrames is the loop that reads incoming frames.
  4683  // It takes care to only read one frame at a time, blocking until the
  4684  // consumer is done with the frame.
  4685  // It's run on its own goroutine.
  4686  func (sc *http2serverConn) readFrames() {
  4687  	sc.srv.markNewGoroutine()
  4688  	gate := make(chan struct{})
  4689  	gateDone := func() { gate <- struct{}{} }
  4690  	for {
  4691  		f, err := sc.framer.ReadFrame()
  4692  		select {
  4693  		case sc.readFrameCh <- http2readFrameResult{f, err, gateDone}:
  4694  		case <-sc.doneServing:
  4695  			return
  4696  		}
  4697  		select {
  4698  		case <-gate:
  4699  		case <-sc.doneServing:
  4700  			return
  4701  		}
  4702  		if http2terminalReadFrameError(err) {
  4703  			return
  4704  		}
  4705  	}
  4706  }
  4707  
  4708  // frameWriteResult is the message passed from writeFrameAsync to the serve goroutine.
  4709  type http2frameWriteResult struct {
  4710  	_   http2incomparable
  4711  	wr  http2FrameWriteRequest // what was written (or attempted)
  4712  	err error                  // result of the writeFrame call
  4713  }
  4714  
  4715  // writeFrameAsync runs in its own goroutine and writes a single frame
  4716  // and then reports when it's done.
  4717  // At most one goroutine can be running writeFrameAsync at a time per
  4718  // serverConn.
  4719  func (sc *http2serverConn) writeFrameAsync(wr http2FrameWriteRequest, wd *http2writeData) {
  4720  	sc.srv.markNewGoroutine()
  4721  	var err error
  4722  	if wd == nil {
  4723  		err = wr.write.writeFrame(sc)
  4724  	} else {
  4725  		err = sc.framer.endWrite()
  4726  	}
  4727  	sc.wroteFrameCh <- http2frameWriteResult{wr: wr, err: err}
  4728  }
  4729  
  4730  func (sc *http2serverConn) closeAllStreamsOnConnClose() {
  4731  	sc.serveG.check()
  4732  	for _, st := range sc.streams {
  4733  		sc.closeStream(st, http2errClientDisconnected)
  4734  	}
  4735  }
  4736  
  4737  func (sc *http2serverConn) stopShutdownTimer() {
  4738  	sc.serveG.check()
  4739  	if t := sc.shutdownTimer; t != nil {
  4740  		t.Stop()
  4741  	}
  4742  }
  4743  
  4744  func (sc *http2serverConn) notePanic() {
  4745  	// Note: this is for serverConn.serve panicking, not http.Handler code.
  4746  	if http2testHookOnPanicMu != nil {
  4747  		http2testHookOnPanicMu.Lock()
  4748  		defer http2testHookOnPanicMu.Unlock()
  4749  	}
  4750  	if http2testHookOnPanic != nil {
  4751  		if e := recover(); e != nil {
  4752  			if http2testHookOnPanic(sc, e) {
  4753  				panic(e)
  4754  			}
  4755  		}
  4756  	}
  4757  }
  4758  
  4759  func (sc *http2serverConn) serve() {
  4760  	sc.serveG.check()
  4761  	defer sc.notePanic()
  4762  	defer sc.conn.Close()
  4763  	defer sc.closeAllStreamsOnConnClose()
  4764  	defer sc.stopShutdownTimer()
  4765  	defer close(sc.doneServing) // unblocks handlers trying to send
  4766  
  4767  	if http2VerboseLogs {
  4768  		sc.vlogf("http2: server connection from %v on %p", sc.conn.RemoteAddr(), sc.hs)
  4769  	}
  4770  
  4771  	sc.writeFrame(http2FrameWriteRequest{
  4772  		write: http2writeSettings{
  4773  			{http2SettingMaxFrameSize, sc.srv.maxReadFrameSize()},
  4774  			{http2SettingMaxConcurrentStreams, sc.advMaxStreams},
  4775  			{http2SettingMaxHeaderListSize, sc.maxHeaderListSize()},
  4776  			{http2SettingHeaderTableSize, sc.srv.maxDecoderHeaderTableSize()},
  4777  			{http2SettingInitialWindowSize, uint32(sc.srv.initialStreamRecvWindowSize())},
  4778  		},
  4779  	})
  4780  	sc.unackedSettings++
  4781  
  4782  	// Each connection starts with initialWindowSize inflow tokens.
  4783  	// If a higher value is configured, we add more tokens.
  4784  	if diff := sc.srv.initialConnRecvWindowSize() - http2initialWindowSize; diff > 0 {
  4785  		sc.sendWindowUpdate(nil, int(diff))
  4786  	}
  4787  
  4788  	if err := sc.readPreface(); err != nil {
  4789  		sc.condlogf(err, "http2: server: error reading preface from client %v: %v", sc.conn.RemoteAddr(), err)
  4790  		return
  4791  	}
  4792  	// Now that we've got the preface, get us out of the
  4793  	// "StateNew" state. We can't go directly to idle, though.
  4794  	// Active means we read some data and anticipate a request. We'll
  4795  	// do another Active when we get a HEADERS frame.
  4796  	sc.setConnState(StateActive)
  4797  	sc.setConnState(StateIdle)
  4798  
  4799  	if sc.srv.IdleTimeout > 0 {
  4800  		sc.idleTimer = sc.srv.afterFunc(sc.srv.IdleTimeout, sc.onIdleTimer)
  4801  		defer sc.idleTimer.Stop()
  4802  	}
  4803  
  4804  	go sc.readFrames() // closed by defer sc.conn.Close above
  4805  
  4806  	settingsTimer := sc.srv.afterFunc(http2firstSettingsTimeout, sc.onSettingsTimer)
  4807  	defer settingsTimer.Stop()
  4808  
  4809  	loopNum := 0
  4810  	for {
  4811  		loopNum++
  4812  		select {
  4813  		case wr := <-sc.wantWriteFrameCh:
  4814  			if se, ok := wr.write.(http2StreamError); ok {
  4815  				sc.resetStream(se)
  4816  				break
  4817  			}
  4818  			sc.writeFrame(wr)
  4819  		case res := <-sc.wroteFrameCh:
  4820  			sc.wroteFrame(res)
  4821  		case res := <-sc.readFrameCh:
  4822  			// Process any written frames before reading new frames from the client since a
  4823  			// written frame could have triggered a new stream to be started.
  4824  			if sc.writingFrameAsync {
  4825  				select {
  4826  				case wroteRes := <-sc.wroteFrameCh:
  4827  					sc.wroteFrame(wroteRes)
  4828  				default:
  4829  				}
  4830  			}
  4831  			if !sc.processFrameFromReader(res) {
  4832  				return
  4833  			}
  4834  			res.readMore()
  4835  			if settingsTimer != nil {
  4836  				settingsTimer.Stop()
  4837  				settingsTimer = nil
  4838  			}
  4839  		case m := <-sc.bodyReadCh:
  4840  			sc.noteBodyRead(m.st, m.n)
  4841  		case msg := <-sc.serveMsgCh:
  4842  			switch v := msg.(type) {
  4843  			case func(int):
  4844  				v(loopNum) // for testing
  4845  			case *http2serverMessage:
  4846  				switch v {
  4847  				case http2settingsTimerMsg:
  4848  					sc.logf("timeout waiting for SETTINGS frames from %v", sc.conn.RemoteAddr())
  4849  					return
  4850  				case http2idleTimerMsg:
  4851  					sc.vlogf("connection is idle")
  4852  					sc.goAway(http2ErrCodeNo)
  4853  				case http2shutdownTimerMsg:
  4854  					sc.vlogf("GOAWAY close timer fired; closing conn from %v", sc.conn.RemoteAddr())
  4855  					return
  4856  				case http2gracefulShutdownMsg:
  4857  					sc.startGracefulShutdownInternal()
  4858  				case http2handlerDoneMsg:
  4859  					sc.handlerDone()
  4860  				default:
  4861  					panic("unknown timer")
  4862  				}
  4863  			case *http2startPushRequest:
  4864  				sc.startPush(v)
  4865  			case func(*http2serverConn):
  4866  				v(sc)
  4867  			default:
  4868  				panic(fmt.Sprintf("unexpected type %T", v))
  4869  			}
  4870  		}
  4871  
  4872  		// If the peer is causing us to generate a lot of control frames,
  4873  		// but not reading them from us, assume they are trying to make us
  4874  		// run out of memory.
  4875  		if sc.queuedControlFrames > sc.srv.maxQueuedControlFrames() {
  4876  			sc.vlogf("http2: too many control frames in send queue, closing connection")
  4877  			return
  4878  		}
  4879  
  4880  		// Start the shutdown timer after sending a GOAWAY. When sending GOAWAY
  4881  		// with no error code (graceful shutdown), don't start the timer until
  4882  		// all open streams have been completed.
  4883  		sentGoAway := sc.inGoAway && !sc.needToSendGoAway && !sc.writingFrame
  4884  		gracefulShutdownComplete := sc.goAwayCode == http2ErrCodeNo && sc.curOpenStreams() == 0
  4885  		if sentGoAway && sc.shutdownTimer == nil && (sc.goAwayCode != http2ErrCodeNo || gracefulShutdownComplete) {
  4886  			sc.shutDownIn(http2goAwayTimeout)
  4887  		}
  4888  	}
  4889  }
  4890  
  4891  type http2serverMessage int
  4892  
  4893  // Message values sent to serveMsgCh.
  4894  var (
  4895  	http2settingsTimerMsg    = new(http2serverMessage)
  4896  	http2idleTimerMsg        = new(http2serverMessage)
  4897  	http2shutdownTimerMsg    = new(http2serverMessage)
  4898  	http2gracefulShutdownMsg = new(http2serverMessage)
  4899  	http2handlerDoneMsg      = new(http2serverMessage)
  4900  )
  4901  
  4902  func (sc *http2serverConn) onSettingsTimer() { sc.sendServeMsg(http2settingsTimerMsg) }
  4903  
  4904  func (sc *http2serverConn) onIdleTimer() { sc.sendServeMsg(http2idleTimerMsg) }
  4905  
  4906  func (sc *http2serverConn) onShutdownTimer() { sc.sendServeMsg(http2shutdownTimerMsg) }
  4907  
  4908  func (sc *http2serverConn) sendServeMsg(msg interface{}) {
  4909  	sc.serveG.checkNotOn() // NOT
  4910  	select {
  4911  	case sc.serveMsgCh <- msg:
  4912  	case <-sc.doneServing:
  4913  	}
  4914  }
  4915  
  4916  var http2errPrefaceTimeout = errors.New("timeout waiting for client preface")
  4917  
  4918  // readPreface reads the ClientPreface greeting from the peer or
  4919  // returns errPrefaceTimeout on timeout, or an error if the greeting
  4920  // is invalid.
  4921  func (sc *http2serverConn) readPreface() error {
  4922  	if sc.sawClientPreface {
  4923  		return nil
  4924  	}
  4925  	errc := make(chan error, 1)
  4926  	go func() {
  4927  		// Read the client preface
  4928  		buf := make([]byte, len(http2ClientPreface))
  4929  		if _, err := io.ReadFull(sc.conn, buf); err != nil {
  4930  			errc <- err
  4931  		} else if !bytes.Equal(buf, http2clientPreface) {
  4932  			errc <- fmt.Errorf("bogus greeting %q", buf)
  4933  		} else {
  4934  			errc <- nil
  4935  		}
  4936  	}()
  4937  	timer := sc.srv.newTimer(http2prefaceTimeout) // TODO: configurable on *Server?
  4938  	defer timer.Stop()
  4939  	select {
  4940  	case <-timer.C():
  4941  		return http2errPrefaceTimeout
  4942  	case err := <-errc:
  4943  		if err == nil {
  4944  			if http2VerboseLogs {
  4945  				sc.vlogf("http2: server: client %v said hello", sc.conn.RemoteAddr())
  4946  			}
  4947  		}
  4948  		return err
  4949  	}
  4950  }
  4951  
  4952  var http2errChanPool = sync.Pool{
  4953  	New: func() interface{} { return make(chan error, 1) },
  4954  }
  4955  
  4956  var http2writeDataPool = sync.Pool{
  4957  	New: func() interface{} { return new(http2writeData) },
  4958  }
  4959  
  4960  // writeDataFromHandler writes DATA response frames from a handler on
  4961  // the given stream.
  4962  func (sc *http2serverConn) writeDataFromHandler(stream *http2stream, data []byte, endStream bool) error {
  4963  	ch := http2errChanPool.Get().(chan error)
  4964  	writeArg := http2writeDataPool.Get().(*http2writeData)
  4965  	*writeArg = http2writeData{stream.id, data, endStream}
  4966  	err := sc.writeFrameFromHandler(http2FrameWriteRequest{
  4967  		write:  writeArg,
  4968  		stream: stream,
  4969  		done:   ch,
  4970  	})
  4971  	if err != nil {
  4972  		return err
  4973  	}
  4974  	var frameWriteDone bool // the frame write is done (successfully or not)
  4975  	select {
  4976  	case err = <-ch:
  4977  		frameWriteDone = true
  4978  	case <-sc.doneServing:
  4979  		return http2errClientDisconnected
  4980  	case <-stream.cw:
  4981  		// If both ch and stream.cw were ready (as might
  4982  		// happen on the final Write after an http.Handler
  4983  		// ends), prefer the write result. Otherwise this
  4984  		// might just be us successfully closing the stream.
  4985  		// The writeFrameAsync and serve goroutines guarantee
  4986  		// that the ch send will happen before the stream.cw
  4987  		// close.
  4988  		select {
  4989  		case err = <-ch:
  4990  			frameWriteDone = true
  4991  		default:
  4992  			return http2errStreamClosed
  4993  		}
  4994  	}
  4995  	http2errChanPool.Put(ch)
  4996  	if frameWriteDone {
  4997  		http2writeDataPool.Put(writeArg)
  4998  	}
  4999  	return err
  5000  }
  5001  
  5002  // writeFrameFromHandler sends wr to sc.wantWriteFrameCh, but aborts
  5003  // if the connection has gone away.
  5004  //
  5005  // This must not be run from the serve goroutine itself, else it might
  5006  // deadlock writing to sc.wantWriteFrameCh (which is only mildly
  5007  // buffered and is read by serve itself). If you're on the serve
  5008  // goroutine, call writeFrame instead.
  5009  func (sc *http2serverConn) writeFrameFromHandler(wr http2FrameWriteRequest) error {
  5010  	sc.serveG.checkNotOn() // NOT
  5011  	select {
  5012  	case sc.wantWriteFrameCh <- wr:
  5013  		return nil
  5014  	case <-sc.doneServing:
  5015  		// Serve loop is gone.
  5016  		// Client has closed their connection to the server.
  5017  		return http2errClientDisconnected
  5018  	}
  5019  }
  5020  
  5021  // writeFrame schedules a frame to write and sends it if there's nothing
  5022  // already being written.
  5023  //
  5024  // There is no pushback here (the serve goroutine never blocks). It's
  5025  // the http.Handlers that block, waiting for their previous frames to
  5026  // make it onto the wire
  5027  //
  5028  // If you're not on the serve goroutine, use writeFrameFromHandler instead.
  5029  func (sc *http2serverConn) writeFrame(wr http2FrameWriteRequest) {
  5030  	sc.serveG.check()
  5031  
  5032  	// If true, wr will not be written and wr.done will not be signaled.
  5033  	var ignoreWrite bool
  5034  
  5035  	// We are not allowed to write frames on closed streams. RFC 7540 Section
  5036  	// 5.1.1 says: "An endpoint MUST NOT send frames other than PRIORITY on
  5037  	// a closed stream." Our server never sends PRIORITY, so that exception
  5038  	// does not apply.
  5039  	//
  5040  	// The serverConn might close an open stream while the stream's handler
  5041  	// is still running. For example, the server might close a stream when it
  5042  	// receives bad data from the client. If this happens, the handler might
  5043  	// attempt to write a frame after the stream has been closed (since the
  5044  	// handler hasn't yet been notified of the close). In this case, we simply
  5045  	// ignore the frame. The handler will notice that the stream is closed when
  5046  	// it waits for the frame to be written.
  5047  	//
  5048  	// As an exception to this rule, we allow sending RST_STREAM after close.
  5049  	// This allows us to immediately reject new streams without tracking any
  5050  	// state for those streams (except for the queued RST_STREAM frame). This
  5051  	// may result in duplicate RST_STREAMs in some cases, but the client should
  5052  	// ignore those.
  5053  	if wr.StreamID() != 0 {
  5054  		_, isReset := wr.write.(http2StreamError)
  5055  		if state, _ := sc.state(wr.StreamID()); state == http2stateClosed && !isReset {
  5056  			ignoreWrite = true
  5057  		}
  5058  	}
  5059  
  5060  	// Don't send a 100-continue response if we've already sent headers.
  5061  	// See golang.org/issue/14030.
  5062  	switch wr.write.(type) {
  5063  	case *http2writeResHeaders:
  5064  		wr.stream.wroteHeaders = true
  5065  	case http2write100ContinueHeadersFrame:
  5066  		if wr.stream.wroteHeaders {
  5067  			// We do not need to notify wr.done because this frame is
  5068  			// never written with wr.done != nil.
  5069  			if wr.done != nil {
  5070  				panic("wr.done != nil for write100ContinueHeadersFrame")
  5071  			}
  5072  			ignoreWrite = true
  5073  		}
  5074  	}
  5075  
  5076  	if !ignoreWrite {
  5077  		if wr.isControl() {
  5078  			sc.queuedControlFrames++
  5079  			// For extra safety, detect wraparounds, which should not happen,
  5080  			// and pull the plug.
  5081  			if sc.queuedControlFrames < 0 {
  5082  				sc.conn.Close()
  5083  			}
  5084  		}
  5085  		sc.writeSched.Push(wr)
  5086  	}
  5087  	sc.scheduleFrameWrite()
  5088  }
  5089  
  5090  // startFrameWrite starts a goroutine to write wr (in a separate
  5091  // goroutine since that might block on the network), and updates the
  5092  // serve goroutine's state about the world, updated from info in wr.
  5093  func (sc *http2serverConn) startFrameWrite(wr http2FrameWriteRequest) {
  5094  	sc.serveG.check()
  5095  	if sc.writingFrame {
  5096  		panic("internal error: can only be writing one frame at a time")
  5097  	}
  5098  
  5099  	st := wr.stream
  5100  	if st != nil {
  5101  		switch st.state {
  5102  		case http2stateHalfClosedLocal:
  5103  			switch wr.write.(type) {
  5104  			case http2StreamError, http2handlerPanicRST, http2writeWindowUpdate:
  5105  				// RFC 7540 Section 5.1 allows sending RST_STREAM, PRIORITY, and WINDOW_UPDATE
  5106  				// in this state. (We never send PRIORITY from the server, so that is not checked.)
  5107  			default:
  5108  				panic(fmt.Sprintf("internal error: attempt to send frame on a half-closed-local stream: %v", wr))
  5109  			}
  5110  		case http2stateClosed:
  5111  			panic(fmt.Sprintf("internal error: attempt to send frame on a closed stream: %v", wr))
  5112  		}
  5113  	}
  5114  	if wpp, ok := wr.write.(*http2writePushPromise); ok {
  5115  		var err error
  5116  		wpp.promisedID, err = wpp.allocatePromisedID()
  5117  		if err != nil {
  5118  			sc.writingFrameAsync = false
  5119  			wr.replyToWriter(err)
  5120  			return
  5121  		}
  5122  	}
  5123  
  5124  	sc.writingFrame = true
  5125  	sc.needsFrameFlush = true
  5126  	if wr.write.staysWithinBuffer(sc.bw.Available()) {
  5127  		sc.writingFrameAsync = false
  5128  		err := wr.write.writeFrame(sc)
  5129  		sc.wroteFrame(http2frameWriteResult{wr: wr, err: err})
  5130  	} else if wd, ok := wr.write.(*http2writeData); ok {
  5131  		// Encode the frame in the serve goroutine, to ensure we don't have
  5132  		// any lingering asynchronous references to data passed to Write.
  5133  		// See https://go.dev/issue/58446.
  5134  		sc.framer.startWriteDataPadded(wd.streamID, wd.endStream, wd.p, nil)
  5135  		sc.writingFrameAsync = true
  5136  		go sc.writeFrameAsync(wr, wd)
  5137  	} else {
  5138  		sc.writingFrameAsync = true
  5139  		go sc.writeFrameAsync(wr, nil)
  5140  	}
  5141  }
  5142  
  5143  // errHandlerPanicked is the error given to any callers blocked in a read from
  5144  // Request.Body when the main goroutine panics. Since most handlers read in the
  5145  // main ServeHTTP goroutine, this will show up rarely.
  5146  var http2errHandlerPanicked = errors.New("http2: handler panicked")
  5147  
  5148  // wroteFrame is called on the serve goroutine with the result of
  5149  // whatever happened on writeFrameAsync.
  5150  func (sc *http2serverConn) wroteFrame(res http2frameWriteResult) {
  5151  	sc.serveG.check()
  5152  	if !sc.writingFrame {
  5153  		panic("internal error: expected to be already writing a frame")
  5154  	}
  5155  	sc.writingFrame = false
  5156  	sc.writingFrameAsync = false
  5157  
  5158  	wr := res.wr
  5159  
  5160  	if http2writeEndsStream(wr.write) {
  5161  		st := wr.stream
  5162  		if st == nil {
  5163  			panic("internal error: expecting non-nil stream")
  5164  		}
  5165  		switch st.state {
  5166  		case http2stateOpen:
  5167  			// Here we would go to stateHalfClosedLocal in
  5168  			// theory, but since our handler is done and
  5169  			// the net/http package provides no mechanism
  5170  			// for closing a ResponseWriter while still
  5171  			// reading data (see possible TODO at top of
  5172  			// this file), we go into closed state here
  5173  			// anyway, after telling the peer we're
  5174  			// hanging up on them. We'll transition to
  5175  			// stateClosed after the RST_STREAM frame is
  5176  			// written.
  5177  			st.state = http2stateHalfClosedLocal
  5178  			// Section 8.1: a server MAY request that the client abort
  5179  			// transmission of a request without error by sending a
  5180  			// RST_STREAM with an error code of NO_ERROR after sending
  5181  			// a complete response.
  5182  			sc.resetStream(http2streamError(st.id, http2ErrCodeNo))
  5183  		case http2stateHalfClosedRemote:
  5184  			sc.closeStream(st, http2errHandlerComplete)
  5185  		}
  5186  	} else {
  5187  		switch v := wr.write.(type) {
  5188  		case http2StreamError:
  5189  			// st may be unknown if the RST_STREAM was generated to reject bad input.
  5190  			if st, ok := sc.streams[v.StreamID]; ok {
  5191  				sc.closeStream(st, v)
  5192  			}
  5193  		case http2handlerPanicRST:
  5194  			sc.closeStream(wr.stream, http2errHandlerPanicked)
  5195  		}
  5196  	}
  5197  
  5198  	// Reply (if requested) to unblock the ServeHTTP goroutine.
  5199  	wr.replyToWriter(res.err)
  5200  
  5201  	sc.scheduleFrameWrite()
  5202  }
  5203  
  5204  // scheduleFrameWrite tickles the frame writing scheduler.
  5205  //
  5206  // If a frame is already being written, nothing happens. This will be called again
  5207  // when the frame is done being written.
  5208  //
  5209  // If a frame isn't being written and we need to send one, the best frame
  5210  // to send is selected by writeSched.
  5211  //
  5212  // If a frame isn't being written and there's nothing else to send, we
  5213  // flush the write buffer.
  5214  func (sc *http2serverConn) scheduleFrameWrite() {
  5215  	sc.serveG.check()
  5216  	if sc.writingFrame || sc.inFrameScheduleLoop {
  5217  		return
  5218  	}
  5219  	sc.inFrameScheduleLoop = true
  5220  	for !sc.writingFrameAsync {
  5221  		if sc.needToSendGoAway {
  5222  			sc.needToSendGoAway = false
  5223  			sc.startFrameWrite(http2FrameWriteRequest{
  5224  				write: &http2writeGoAway{
  5225  					maxStreamID: sc.maxClientStreamID,
  5226  					code:        sc.goAwayCode,
  5227  				},
  5228  			})
  5229  			continue
  5230  		}
  5231  		if sc.needToSendSettingsAck {
  5232  			sc.needToSendSettingsAck = false
  5233  			sc.startFrameWrite(http2FrameWriteRequest{write: http2writeSettingsAck{}})
  5234  			continue
  5235  		}
  5236  		if !sc.inGoAway || sc.goAwayCode == http2ErrCodeNo {
  5237  			if wr, ok := sc.writeSched.Pop(); ok {
  5238  				if wr.isControl() {
  5239  					sc.queuedControlFrames--
  5240  				}
  5241  				sc.startFrameWrite(wr)
  5242  				continue
  5243  			}
  5244  		}
  5245  		if sc.needsFrameFlush {
  5246  			sc.startFrameWrite(http2FrameWriteRequest{write: http2flushFrameWriter{}})
  5247  			sc.needsFrameFlush = false // after startFrameWrite, since it sets this true
  5248  			continue
  5249  		}
  5250  		break
  5251  	}
  5252  	sc.inFrameScheduleLoop = false
  5253  }
  5254  
  5255  // startGracefulShutdown gracefully shuts down a connection. This
  5256  // sends GOAWAY with ErrCodeNo to tell the client we're gracefully
  5257  // shutting down. The connection isn't closed until all current
  5258  // streams are done.
  5259  //
  5260  // startGracefulShutdown returns immediately; it does not wait until
  5261  // the connection has shut down.
  5262  func (sc *http2serverConn) startGracefulShutdown() {
  5263  	sc.serveG.checkNotOn() // NOT
  5264  	sc.shutdownOnce.Do(func() { sc.sendServeMsg(http2gracefulShutdownMsg) })
  5265  }
  5266  
  5267  // After sending GOAWAY with an error code (non-graceful shutdown), the
  5268  // connection will close after goAwayTimeout.
  5269  //
  5270  // If we close the connection immediately after sending GOAWAY, there may
  5271  // be unsent data in our kernel receive buffer, which will cause the kernel
  5272  // to send a TCP RST on close() instead of a FIN. This RST will abort the
  5273  // connection immediately, whether or not the client had received the GOAWAY.
  5274  //
  5275  // Ideally we should delay for at least 1 RTT + epsilon so the client has
  5276  // a chance to read the GOAWAY and stop sending messages. Measuring RTT
  5277  // is hard, so we approximate with 1 second. See golang.org/issue/18701.
  5278  //
  5279  // This is a var so it can be shorter in tests, where all requests uses the
  5280  // loopback interface making the expected RTT very small.
  5281  //
  5282  // TODO: configurable?
  5283  var http2goAwayTimeout = 1 * time.Second
  5284  
  5285  func (sc *http2serverConn) startGracefulShutdownInternal() {
  5286  	sc.goAway(http2ErrCodeNo)
  5287  }
  5288  
  5289  func (sc *http2serverConn) goAway(code http2ErrCode) {
  5290  	sc.serveG.check()
  5291  	if sc.inGoAway {
  5292  		if sc.goAwayCode == http2ErrCodeNo {
  5293  			sc.goAwayCode = code
  5294  		}
  5295  		return
  5296  	}
  5297  	sc.inGoAway = true
  5298  	sc.needToSendGoAway = true
  5299  	sc.goAwayCode = code
  5300  	sc.scheduleFrameWrite()
  5301  }
  5302  
  5303  func (sc *http2serverConn) shutDownIn(d time.Duration) {
  5304  	sc.serveG.check()
  5305  	sc.shutdownTimer = sc.srv.afterFunc(d, sc.onShutdownTimer)
  5306  }
  5307  
  5308  func (sc *http2serverConn) resetStream(se http2StreamError) {
  5309  	sc.serveG.check()
  5310  	sc.writeFrame(http2FrameWriteRequest{write: se})
  5311  	if st, ok := sc.streams[se.StreamID]; ok {
  5312  		st.resetQueued = true
  5313  	}
  5314  }
  5315  
  5316  // processFrameFromReader processes the serve loop's read from readFrameCh from the
  5317  // frame-reading goroutine.
  5318  // processFrameFromReader returns whether the connection should be kept open.
  5319  func (sc *http2serverConn) processFrameFromReader(res http2readFrameResult) bool {
  5320  	sc.serveG.check()
  5321  	err := res.err
  5322  	if err != nil {
  5323  		if err == http2ErrFrameTooLarge {
  5324  			sc.goAway(http2ErrCodeFrameSize)
  5325  			return true // goAway will close the loop
  5326  		}
  5327  		clientGone := err == io.EOF || err == io.ErrUnexpectedEOF || http2isClosedConnError(err)
  5328  		if clientGone {
  5329  			// TODO: could we also get into this state if
  5330  			// the peer does a half close
  5331  			// (e.g. CloseWrite) because they're done
  5332  			// sending frames but they're still wanting
  5333  			// our open replies?  Investigate.
  5334  			// TODO: add CloseWrite to crypto/tls.Conn first
  5335  			// so we have a way to test this? I suppose
  5336  			// just for testing we could have a non-TLS mode.
  5337  			return false
  5338  		}
  5339  	} else {
  5340  		f := res.f
  5341  		if http2VerboseLogs {
  5342  			sc.vlogf("http2: server read frame %v", http2summarizeFrame(f))
  5343  		}
  5344  		err = sc.processFrame(f)
  5345  		if err == nil {
  5346  			return true
  5347  		}
  5348  	}
  5349  
  5350  	switch ev := err.(type) {
  5351  	case http2StreamError:
  5352  		sc.resetStream(ev)
  5353  		return true
  5354  	case http2goAwayFlowError:
  5355  		sc.goAway(http2ErrCodeFlowControl)
  5356  		return true
  5357  	case http2ConnectionError:
  5358  		if res.f != nil {
  5359  			if id := res.f.Header().StreamID; id > sc.maxClientStreamID {
  5360  				sc.maxClientStreamID = id
  5361  			}
  5362  		}
  5363  		sc.logf("http2: server connection error from %v: %v", sc.conn.RemoteAddr(), ev)
  5364  		sc.goAway(http2ErrCode(ev))
  5365  		return true // goAway will handle shutdown
  5366  	default:
  5367  		if res.err != nil {
  5368  			sc.vlogf("http2: server closing client connection; error reading frame from client %s: %v", sc.conn.RemoteAddr(), err)
  5369  		} else {
  5370  			sc.logf("http2: server closing client connection: %v", err)
  5371  		}
  5372  		return false
  5373  	}
  5374  }
  5375  
  5376  func (sc *http2serverConn) processFrame(f http2Frame) error {
  5377  	sc.serveG.check()
  5378  
  5379  	// First frame received must be SETTINGS.
  5380  	if !sc.sawFirstSettings {
  5381  		if _, ok := f.(*http2SettingsFrame); !ok {
  5382  			return sc.countError("first_settings", http2ConnectionError(http2ErrCodeProtocol))
  5383  		}
  5384  		sc.sawFirstSettings = true
  5385  	}
  5386  
  5387  	// Discard frames for streams initiated after the identified last
  5388  	// stream sent in a GOAWAY, or all frames after sending an error.
  5389  	// We still need to return connection-level flow control for DATA frames.
  5390  	// RFC 9113 Section 6.8.
  5391  	if sc.inGoAway && (sc.goAwayCode != http2ErrCodeNo || f.Header().StreamID > sc.maxClientStreamID) {
  5392  
  5393  		if f, ok := f.(*http2DataFrame); ok {
  5394  			if !sc.inflow.take(f.Length) {
  5395  				return sc.countError("data_flow", http2streamError(f.Header().StreamID, http2ErrCodeFlowControl))
  5396  			}
  5397  			sc.sendWindowUpdate(nil, int(f.Length)) // conn-level
  5398  		}
  5399  		return nil
  5400  	}
  5401  
  5402  	switch f := f.(type) {
  5403  	case *http2SettingsFrame:
  5404  		return sc.processSettings(f)
  5405  	case *http2MetaHeadersFrame:
  5406  		return sc.processHeaders(f)
  5407  	case *http2WindowUpdateFrame:
  5408  		return sc.processWindowUpdate(f)
  5409  	case *http2PingFrame:
  5410  		return sc.processPing(f)
  5411  	case *http2DataFrame:
  5412  		return sc.processData(f)
  5413  	case *http2RSTStreamFrame:
  5414  		return sc.processResetStream(f)
  5415  	case *http2PriorityFrame:
  5416  		return sc.processPriority(f)
  5417  	case *http2GoAwayFrame:
  5418  		return sc.processGoAway(f)
  5419  	case *http2PushPromiseFrame:
  5420  		// A client cannot push. Thus, servers MUST treat the receipt of a PUSH_PROMISE
  5421  		// frame as a connection error (Section 5.4.1) of type PROTOCOL_ERROR.
  5422  		return sc.countError("push_promise", http2ConnectionError(http2ErrCodeProtocol))
  5423  	default:
  5424  		sc.vlogf("http2: server ignoring frame: %v", f.Header())
  5425  		return nil
  5426  	}
  5427  }
  5428  
  5429  func (sc *http2serverConn) processPing(f *http2PingFrame) error {
  5430  	sc.serveG.check()
  5431  	if f.IsAck() {
  5432  		// 6.7 PING: " An endpoint MUST NOT respond to PING frames
  5433  		// containing this flag."
  5434  		return nil
  5435  	}
  5436  	if f.StreamID != 0 {
  5437  		// "PING frames are not associated with any individual
  5438  		// stream. If a PING frame is received with a stream
  5439  		// identifier field value other than 0x0, the recipient MUST
  5440  		// respond with a connection error (Section 5.4.1) of type
  5441  		// PROTOCOL_ERROR."
  5442  		return sc.countError("ping_on_stream", http2ConnectionError(http2ErrCodeProtocol))
  5443  	}
  5444  	sc.writeFrame(http2FrameWriteRequest{write: http2writePingAck{f}})
  5445  	return nil
  5446  }
  5447  
  5448  func (sc *http2serverConn) processWindowUpdate(f *http2WindowUpdateFrame) error {
  5449  	sc.serveG.check()
  5450  	switch {
  5451  	case f.StreamID != 0: // stream-level flow control
  5452  		state, st := sc.state(f.StreamID)
  5453  		if state == http2stateIdle {
  5454  			// Section 5.1: "Receiving any frame other than HEADERS
  5455  			// or PRIORITY on a stream in this state MUST be
  5456  			// treated as a connection error (Section 5.4.1) of
  5457  			// type PROTOCOL_ERROR."
  5458  			return sc.countError("stream_idle", http2ConnectionError(http2ErrCodeProtocol))
  5459  		}
  5460  		if st == nil {
  5461  			// "WINDOW_UPDATE can be sent by a peer that has sent a
  5462  			// frame bearing the END_STREAM flag. This means that a
  5463  			// receiver could receive a WINDOW_UPDATE frame on a "half
  5464  			// closed (remote)" or "closed" stream. A receiver MUST
  5465  			// NOT treat this as an error, see Section 5.1."
  5466  			return nil
  5467  		}
  5468  		if !st.flow.add(int32(f.Increment)) {
  5469  			return sc.countError("bad_flow", http2streamError(f.StreamID, http2ErrCodeFlowControl))
  5470  		}
  5471  	default: // connection-level flow control
  5472  		if !sc.flow.add(int32(f.Increment)) {
  5473  			return http2goAwayFlowError{}
  5474  		}
  5475  	}
  5476  	sc.scheduleFrameWrite()
  5477  	return nil
  5478  }
  5479  
  5480  func (sc *http2serverConn) processResetStream(f *http2RSTStreamFrame) error {
  5481  	sc.serveG.check()
  5482  
  5483  	state, st := sc.state(f.StreamID)
  5484  	if state == http2stateIdle {
  5485  		// 6.4 "RST_STREAM frames MUST NOT be sent for a
  5486  		// stream in the "idle" state. If a RST_STREAM frame
  5487  		// identifying an idle stream is received, the
  5488  		// recipient MUST treat this as a connection error
  5489  		// (Section 5.4.1) of type PROTOCOL_ERROR.
  5490  		return sc.countError("reset_idle_stream", http2ConnectionError(http2ErrCodeProtocol))
  5491  	}
  5492  	if st != nil {
  5493  		st.cancelCtx()
  5494  		sc.closeStream(st, http2streamError(f.StreamID, f.ErrCode))
  5495  	}
  5496  	return nil
  5497  }
  5498  
  5499  func (sc *http2serverConn) closeStream(st *http2stream, err error) {
  5500  	sc.serveG.check()
  5501  	if st.state == http2stateIdle || st.state == http2stateClosed {
  5502  		panic(fmt.Sprintf("invariant; can't close stream in state %v", st.state))
  5503  	}
  5504  	st.state = http2stateClosed
  5505  	if st.readDeadline != nil {
  5506  		st.readDeadline.Stop()
  5507  	}
  5508  	if st.writeDeadline != nil {
  5509  		st.writeDeadline.Stop()
  5510  	}
  5511  	if st.isPushed() {
  5512  		sc.curPushedStreams--
  5513  	} else {
  5514  		sc.curClientStreams--
  5515  	}
  5516  	delete(sc.streams, st.id)
  5517  	if len(sc.streams) == 0 {
  5518  		sc.setConnState(StateIdle)
  5519  		if sc.srv.IdleTimeout > 0 && sc.idleTimer != nil {
  5520  			sc.idleTimer.Reset(sc.srv.IdleTimeout)
  5521  		}
  5522  		if http2h1ServerKeepAlivesDisabled(sc.hs) {
  5523  			sc.startGracefulShutdownInternal()
  5524  		}
  5525  	}
  5526  	if p := st.body; p != nil {
  5527  		// Return any buffered unread bytes worth of conn-level flow control.
  5528  		// See golang.org/issue/16481
  5529  		sc.sendWindowUpdate(nil, p.Len())
  5530  
  5531  		p.CloseWithError(err)
  5532  	}
  5533  	if e, ok := err.(http2StreamError); ok {
  5534  		if e.Cause != nil {
  5535  			err = e.Cause
  5536  		} else {
  5537  			err = http2errStreamClosed
  5538  		}
  5539  	}
  5540  	st.closeErr = err
  5541  	st.cancelCtx()
  5542  	st.cw.Close() // signals Handler's CloseNotifier, unblocks writes, etc
  5543  	sc.writeSched.CloseStream(st.id)
  5544  }
  5545  
  5546  func (sc *http2serverConn) processSettings(f *http2SettingsFrame) error {
  5547  	sc.serveG.check()
  5548  	if f.IsAck() {
  5549  		sc.unackedSettings--
  5550  		if sc.unackedSettings < 0 {
  5551  			// Why is the peer ACKing settings we never sent?
  5552  			// The spec doesn't mention this case, but
  5553  			// hang up on them anyway.
  5554  			return sc.countError("ack_mystery", http2ConnectionError(http2ErrCodeProtocol))
  5555  		}
  5556  		return nil
  5557  	}
  5558  	if f.NumSettings() > 100 || f.HasDuplicates() {
  5559  		// This isn't actually in the spec, but hang up on
  5560  		// suspiciously large settings frames or those with
  5561  		// duplicate entries.
  5562  		return sc.countError("settings_big_or_dups", http2ConnectionError(http2ErrCodeProtocol))
  5563  	}
  5564  	if err := f.ForeachSetting(sc.processSetting); err != nil {
  5565  		return err
  5566  	}
  5567  	// TODO: judging by RFC 7540, Section 6.5.3 each SETTINGS frame should be
  5568  	// acknowledged individually, even if multiple are received before the ACK.
  5569  	sc.needToSendSettingsAck = true
  5570  	sc.scheduleFrameWrite()
  5571  	return nil
  5572  }
  5573  
  5574  func (sc *http2serverConn) processSetting(s http2Setting) error {
  5575  	sc.serveG.check()
  5576  	if err := s.Valid(); err != nil {
  5577  		return err
  5578  	}
  5579  	if http2VerboseLogs {
  5580  		sc.vlogf("http2: server processing setting %v", s)
  5581  	}
  5582  	switch s.ID {
  5583  	case http2SettingHeaderTableSize:
  5584  		sc.hpackEncoder.SetMaxDynamicTableSize(s.Val)
  5585  	case http2SettingEnablePush:
  5586  		sc.pushEnabled = s.Val != 0
  5587  	case http2SettingMaxConcurrentStreams:
  5588  		sc.clientMaxStreams = s.Val
  5589  	case http2SettingInitialWindowSize:
  5590  		return sc.processSettingInitialWindowSize(s.Val)
  5591  	case http2SettingMaxFrameSize:
  5592  		sc.maxFrameSize = int32(s.Val) // the maximum valid s.Val is < 2^31
  5593  	case http2SettingMaxHeaderListSize:
  5594  		sc.peerMaxHeaderListSize = s.Val
  5595  	default:
  5596  		// Unknown setting: "An endpoint that receives a SETTINGS
  5597  		// frame with any unknown or unsupported identifier MUST
  5598  		// ignore that setting."
  5599  		if http2VerboseLogs {
  5600  			sc.vlogf("http2: server ignoring unknown setting %v", s)
  5601  		}
  5602  	}
  5603  	return nil
  5604  }
  5605  
  5606  func (sc *http2serverConn) processSettingInitialWindowSize(val uint32) error {
  5607  	sc.serveG.check()
  5608  	// Note: val already validated to be within range by
  5609  	// processSetting's Valid call.
  5610  
  5611  	// "A SETTINGS frame can alter the initial flow control window
  5612  	// size for all current streams. When the value of
  5613  	// SETTINGS_INITIAL_WINDOW_SIZE changes, a receiver MUST
  5614  	// adjust the size of all stream flow control windows that it
  5615  	// maintains by the difference between the new value and the
  5616  	// old value."
  5617  	old := sc.initialStreamSendWindowSize
  5618  	sc.initialStreamSendWindowSize = int32(val)
  5619  	growth := int32(val) - old // may be negative
  5620  	for _, st := range sc.streams {
  5621  		if !st.flow.add(growth) {
  5622  			// 6.9.2 Initial Flow Control Window Size
  5623  			// "An endpoint MUST treat a change to
  5624  			// SETTINGS_INITIAL_WINDOW_SIZE that causes any flow
  5625  			// control window to exceed the maximum size as a
  5626  			// connection error (Section 5.4.1) of type
  5627  			// FLOW_CONTROL_ERROR."
  5628  			return sc.countError("setting_win_size", http2ConnectionError(http2ErrCodeFlowControl))
  5629  		}
  5630  	}
  5631  	return nil
  5632  }
  5633  
  5634  func (sc *http2serverConn) processData(f *http2DataFrame) error {
  5635  	sc.serveG.check()
  5636  	id := f.Header().StreamID
  5637  
  5638  	data := f.Data()
  5639  	state, st := sc.state(id)
  5640  	if id == 0 || state == http2stateIdle {
  5641  		// Section 6.1: "DATA frames MUST be associated with a
  5642  		// stream. If a DATA frame is received whose stream
  5643  		// identifier field is 0x0, the recipient MUST respond
  5644  		// with a connection error (Section 5.4.1) of type
  5645  		// PROTOCOL_ERROR."
  5646  		//
  5647  		// Section 5.1: "Receiving any frame other than HEADERS
  5648  		// or PRIORITY on a stream in this state MUST be
  5649  		// treated as a connection error (Section 5.4.1) of
  5650  		// type PROTOCOL_ERROR."
  5651  		return sc.countError("data_on_idle", http2ConnectionError(http2ErrCodeProtocol))
  5652  	}
  5653  
  5654  	// "If a DATA frame is received whose stream is not in "open"
  5655  	// or "half closed (local)" state, the recipient MUST respond
  5656  	// with a stream error (Section 5.4.2) of type STREAM_CLOSED."
  5657  	if st == nil || state != http2stateOpen || st.gotTrailerHeader || st.resetQueued {
  5658  		// This includes sending a RST_STREAM if the stream is
  5659  		// in stateHalfClosedLocal (which currently means that
  5660  		// the http.Handler returned, so it's done reading &
  5661  		// done writing). Try to stop the client from sending
  5662  		// more DATA.
  5663  
  5664  		// But still enforce their connection-level flow control,
  5665  		// and return any flow control bytes since we're not going
  5666  		// to consume them.
  5667  		if !sc.inflow.take(f.Length) {
  5668  			return sc.countError("data_flow", http2streamError(id, http2ErrCodeFlowControl))
  5669  		}
  5670  		sc.sendWindowUpdate(nil, int(f.Length)) // conn-level
  5671  
  5672  		if st != nil && st.resetQueued {
  5673  			// Already have a stream error in flight. Don't send another.
  5674  			return nil
  5675  		}
  5676  		return sc.countError("closed", http2streamError(id, http2ErrCodeStreamClosed))
  5677  	}
  5678  	if st.body == nil {
  5679  		panic("internal error: should have a body in this state")
  5680  	}
  5681  
  5682  	// Sender sending more than they'd declared?
  5683  	if st.declBodyBytes != -1 && st.bodyBytes+int64(len(data)) > st.declBodyBytes {
  5684  		if !sc.inflow.take(f.Length) {
  5685  			return sc.countError("data_flow", http2streamError(id, http2ErrCodeFlowControl))
  5686  		}
  5687  		sc.sendWindowUpdate(nil, int(f.Length)) // conn-level
  5688  
  5689  		st.body.CloseWithError(fmt.Errorf("sender tried to send more than declared Content-Length of %d bytes", st.declBodyBytes))
  5690  		// RFC 7540, sec 8.1.2.6: A request or response is also malformed if the
  5691  		// value of a content-length header field does not equal the sum of the
  5692  		// DATA frame payload lengths that form the body.
  5693  		return sc.countError("send_too_much", http2streamError(id, http2ErrCodeProtocol))
  5694  	}
  5695  	if f.Length > 0 {
  5696  		// Check whether the client has flow control quota.
  5697  		if !http2takeInflows(&sc.inflow, &st.inflow, f.Length) {
  5698  			return sc.countError("flow_on_data_length", http2streamError(id, http2ErrCodeFlowControl))
  5699  		}
  5700  
  5701  		if len(data) > 0 {
  5702  			st.bodyBytes += int64(len(data))
  5703  			wrote, err := st.body.Write(data)
  5704  			if err != nil {
  5705  				// The handler has closed the request body.
  5706  				// Return the connection-level flow control for the discarded data,
  5707  				// but not the stream-level flow control.
  5708  				sc.sendWindowUpdate(nil, int(f.Length)-wrote)
  5709  				return nil
  5710  			}
  5711  			if wrote != len(data) {
  5712  				panic("internal error: bad Writer")
  5713  			}
  5714  		}
  5715  
  5716  		// Return any padded flow control now, since we won't
  5717  		// refund it later on body reads.
  5718  		// Call sendWindowUpdate even if there is no padding,
  5719  		// to return buffered flow control credit if the sent
  5720  		// window has shrunk.
  5721  		pad := int32(f.Length) - int32(len(data))
  5722  		sc.sendWindowUpdate32(nil, pad)
  5723  		sc.sendWindowUpdate32(st, pad)
  5724  	}
  5725  	if f.StreamEnded() {
  5726  		st.endStream()
  5727  	}
  5728  	return nil
  5729  }
  5730  
  5731  func (sc *http2serverConn) processGoAway(f *http2GoAwayFrame) error {
  5732  	sc.serveG.check()
  5733  	if f.ErrCode != http2ErrCodeNo {
  5734  		sc.logf("http2: received GOAWAY %+v, starting graceful shutdown", f)
  5735  	} else {
  5736  		sc.vlogf("http2: received GOAWAY %+v, starting graceful shutdown", f)
  5737  	}
  5738  	sc.startGracefulShutdownInternal()
  5739  	// http://tools.ietf.org/html/rfc7540#section-6.8
  5740  	// We should not create any new streams, which means we should disable push.
  5741  	sc.pushEnabled = false
  5742  	return nil
  5743  }
  5744  
  5745  // isPushed reports whether the stream is server-initiated.
  5746  func (st *http2stream) isPushed() bool {
  5747  	return st.id%2 == 0
  5748  }
  5749  
  5750  // endStream closes a Request.Body's pipe. It is called when a DATA
  5751  // frame says a request body is over (or after trailers).
  5752  func (st *http2stream) endStream() {
  5753  	sc := st.sc
  5754  	sc.serveG.check()
  5755  
  5756  	if st.declBodyBytes != -1 && st.declBodyBytes != st.bodyBytes {
  5757  		st.body.CloseWithError(fmt.Errorf("request declared a Content-Length of %d but only wrote %d bytes",
  5758  			st.declBodyBytes, st.bodyBytes))
  5759  	} else {
  5760  		st.body.closeWithErrorAndCode(io.EOF, st.copyTrailersToHandlerRequest)
  5761  		st.body.CloseWithError(io.EOF)
  5762  	}
  5763  	st.state = http2stateHalfClosedRemote
  5764  }
  5765  
  5766  // copyTrailersToHandlerRequest is run in the Handler's goroutine in
  5767  // its Request.Body.Read just before it gets io.EOF.
  5768  func (st *http2stream) copyTrailersToHandlerRequest() {
  5769  	for k, vv := range st.trailer {
  5770  		if _, ok := st.reqTrailer[k]; ok {
  5771  			// Only copy it over it was pre-declared.
  5772  			st.reqTrailer[k] = vv
  5773  		}
  5774  	}
  5775  }
  5776  
  5777  // onReadTimeout is run on its own goroutine (from time.AfterFunc)
  5778  // when the stream's ReadTimeout has fired.
  5779  func (st *http2stream) onReadTimeout() {
  5780  	if st.body != nil {
  5781  		// Wrap the ErrDeadlineExceeded to avoid callers depending on us
  5782  		// returning the bare error.
  5783  		st.body.CloseWithError(fmt.Errorf("%w", os.ErrDeadlineExceeded))
  5784  	}
  5785  }
  5786  
  5787  // onWriteTimeout is run on its own goroutine (from time.AfterFunc)
  5788  // when the stream's WriteTimeout has fired.
  5789  func (st *http2stream) onWriteTimeout() {
  5790  	st.sc.writeFrameFromHandler(http2FrameWriteRequest{write: http2StreamError{
  5791  		StreamID: st.id,
  5792  		Code:     http2ErrCodeInternal,
  5793  		Cause:    os.ErrDeadlineExceeded,
  5794  	}})
  5795  }
  5796  
  5797  func (sc *http2serverConn) processHeaders(f *http2MetaHeadersFrame) error {
  5798  	sc.serveG.check()
  5799  	id := f.StreamID
  5800  	// http://tools.ietf.org/html/rfc7540#section-5.1.1
  5801  	// Streams initiated by a client MUST use odd-numbered stream
  5802  	// identifiers. [...] An endpoint that receives an unexpected
  5803  	// stream identifier MUST respond with a connection error
  5804  	// (Section 5.4.1) of type PROTOCOL_ERROR.
  5805  	if id%2 != 1 {
  5806  		return sc.countError("headers_even", http2ConnectionError(http2ErrCodeProtocol))
  5807  	}
  5808  	// A HEADERS frame can be used to create a new stream or
  5809  	// send a trailer for an open one. If we already have a stream
  5810  	// open, let it process its own HEADERS frame (trailers at this
  5811  	// point, if it's valid).
  5812  	if st := sc.streams[f.StreamID]; st != nil {
  5813  		if st.resetQueued {
  5814  			// We're sending RST_STREAM to close the stream, so don't bother
  5815  			// processing this frame.
  5816  			return nil
  5817  		}
  5818  		// RFC 7540, sec 5.1: If an endpoint receives additional frames, other than
  5819  		// WINDOW_UPDATE, PRIORITY, or RST_STREAM, for a stream that is in
  5820  		// this state, it MUST respond with a stream error (Section 5.4.2) of
  5821  		// type STREAM_CLOSED.
  5822  		if st.state == http2stateHalfClosedRemote {
  5823  			return sc.countError("headers_half_closed", http2streamError(id, http2ErrCodeStreamClosed))
  5824  		}
  5825  		return st.processTrailerHeaders(f)
  5826  	}
  5827  
  5828  	// [...] The identifier of a newly established stream MUST be
  5829  	// numerically greater than all streams that the initiating
  5830  	// endpoint has opened or reserved. [...]  An endpoint that
  5831  	// receives an unexpected stream identifier MUST respond with
  5832  	// a connection error (Section 5.4.1) of type PROTOCOL_ERROR.
  5833  	if id <= sc.maxClientStreamID {
  5834  		return sc.countError("stream_went_down", http2ConnectionError(http2ErrCodeProtocol))
  5835  	}
  5836  	sc.maxClientStreamID = id
  5837  
  5838  	if sc.idleTimer != nil {
  5839  		sc.idleTimer.Stop()
  5840  	}
  5841  
  5842  	// http://tools.ietf.org/html/rfc7540#section-5.1.2
  5843  	// [...] Endpoints MUST NOT exceed the limit set by their peer. An
  5844  	// endpoint that receives a HEADERS frame that causes their
  5845  	// advertised concurrent stream limit to be exceeded MUST treat
  5846  	// this as a stream error (Section 5.4.2) of type PROTOCOL_ERROR
  5847  	// or REFUSED_STREAM.
  5848  	if sc.curClientStreams+1 > sc.advMaxStreams {
  5849  		if sc.unackedSettings == 0 {
  5850  			// They should know better.
  5851  			return sc.countError("over_max_streams", http2streamError(id, http2ErrCodeProtocol))
  5852  		}
  5853  		// Assume it's a network race, where they just haven't
  5854  		// received our last SETTINGS update. But actually
  5855  		// this can't happen yet, because we don't yet provide
  5856  		// a way for users to adjust server parameters at
  5857  		// runtime.
  5858  		return sc.countError("over_max_streams_race", http2streamError(id, http2ErrCodeRefusedStream))
  5859  	}
  5860  
  5861  	initialState := http2stateOpen
  5862  	if f.StreamEnded() {
  5863  		initialState = http2stateHalfClosedRemote
  5864  	}
  5865  	st := sc.newStream(id, 0, initialState)
  5866  
  5867  	if f.HasPriority() {
  5868  		if err := sc.checkPriority(f.StreamID, f.Priority); err != nil {
  5869  			return err
  5870  		}
  5871  		sc.writeSched.AdjustStream(st.id, f.Priority)
  5872  	}
  5873  
  5874  	rw, req, err := sc.newWriterAndRequest(st, f)
  5875  	if err != nil {
  5876  		return err
  5877  	}
  5878  	st.reqTrailer = req.Trailer
  5879  	if st.reqTrailer != nil {
  5880  		st.trailer = make(Header)
  5881  	}
  5882  	st.body = req.Body.(*http2requestBody).pipe // may be nil
  5883  	st.declBodyBytes = req.ContentLength
  5884  
  5885  	handler := sc.handler.ServeHTTP
  5886  	if f.Truncated {
  5887  		// Their header list was too long. Send a 431 error.
  5888  		handler = http2handleHeaderListTooLong
  5889  	} else if err := http2checkValidHTTP2RequestHeaders(req.Header); err != nil {
  5890  		handler = http2new400Handler(err)
  5891  	}
  5892  
  5893  	// The net/http package sets the read deadline from the
  5894  	// http.Server.ReadTimeout during the TLS handshake, but then
  5895  	// passes the connection off to us with the deadline already
  5896  	// set. Disarm it here after the request headers are read,
  5897  	// similar to how the http1 server works. Here it's
  5898  	// technically more like the http1 Server's ReadHeaderTimeout
  5899  	// (in Go 1.8), though. That's a more sane option anyway.
  5900  	if sc.hs.ReadTimeout > 0 {
  5901  		sc.conn.SetReadDeadline(time.Time{})
  5902  		st.readDeadline = sc.srv.afterFunc(sc.hs.ReadTimeout, st.onReadTimeout)
  5903  	}
  5904  
  5905  	return sc.scheduleHandler(id, rw, req, handler)
  5906  }
  5907  
  5908  func (sc *http2serverConn) upgradeRequest(req *Request) {
  5909  	sc.serveG.check()
  5910  	id := uint32(1)
  5911  	sc.maxClientStreamID = id
  5912  	st := sc.newStream(id, 0, http2stateHalfClosedRemote)
  5913  	st.reqTrailer = req.Trailer
  5914  	if st.reqTrailer != nil {
  5915  		st.trailer = make(Header)
  5916  	}
  5917  	rw := sc.newResponseWriter(st, req)
  5918  
  5919  	// Disable any read deadline set by the net/http package
  5920  	// prior to the upgrade.
  5921  	if sc.hs.ReadTimeout > 0 {
  5922  		sc.conn.SetReadDeadline(time.Time{})
  5923  	}
  5924  
  5925  	// This is the first request on the connection,
  5926  	// so start the handler directly rather than going
  5927  	// through scheduleHandler.
  5928  	sc.curHandlers++
  5929  	go sc.runHandler(rw, req, sc.handler.ServeHTTP)
  5930  }
  5931  
  5932  func (st *http2stream) processTrailerHeaders(f *http2MetaHeadersFrame) error {
  5933  	sc := st.sc
  5934  	sc.serveG.check()
  5935  	if st.gotTrailerHeader {
  5936  		return sc.countError("dup_trailers", http2ConnectionError(http2ErrCodeProtocol))
  5937  	}
  5938  	st.gotTrailerHeader = true
  5939  	if !f.StreamEnded() {
  5940  		return sc.countError("trailers_not_ended", http2streamError(st.id, http2ErrCodeProtocol))
  5941  	}
  5942  
  5943  	if len(f.PseudoFields()) > 0 {
  5944  		return sc.countError("trailers_pseudo", http2streamError(st.id, http2ErrCodeProtocol))
  5945  	}
  5946  	if st.trailer != nil {
  5947  		for _, hf := range f.RegularFields() {
  5948  			key := sc.canonicalHeader(hf.Name)
  5949  			if !httpguts.ValidTrailerHeader(key) {
  5950  				// TODO: send more details to the peer somehow. But http2 has
  5951  				// no way to send debug data at a stream level. Discuss with
  5952  				// HTTP folk.
  5953  				return sc.countError("trailers_bogus", http2streamError(st.id, http2ErrCodeProtocol))
  5954  			}
  5955  			st.trailer[key] = append(st.trailer[key], hf.Value)
  5956  		}
  5957  	}
  5958  	st.endStream()
  5959  	return nil
  5960  }
  5961  
  5962  func (sc *http2serverConn) checkPriority(streamID uint32, p http2PriorityParam) error {
  5963  	if streamID == p.StreamDep {
  5964  		// Section 5.3.1: "A stream cannot depend on itself. An endpoint MUST treat
  5965  		// this as a stream error (Section 5.4.2) of type PROTOCOL_ERROR."
  5966  		// Section 5.3.3 says that a stream can depend on one of its dependencies,
  5967  		// so it's only self-dependencies that are forbidden.
  5968  		return sc.countError("priority", http2streamError(streamID, http2ErrCodeProtocol))
  5969  	}
  5970  	return nil
  5971  }
  5972  
  5973  func (sc *http2serverConn) processPriority(f *http2PriorityFrame) error {
  5974  	if err := sc.checkPriority(f.StreamID, f.http2PriorityParam); err != nil {
  5975  		return err
  5976  	}
  5977  	sc.writeSched.AdjustStream(f.StreamID, f.http2PriorityParam)
  5978  	return nil
  5979  }
  5980  
  5981  func (sc *http2serverConn) newStream(id, pusherID uint32, state http2streamState) *http2stream {
  5982  	sc.serveG.check()
  5983  	if id == 0 {
  5984  		panic("internal error: cannot create stream with id 0")
  5985  	}
  5986  
  5987  	ctx, cancelCtx := context.WithCancel(sc.baseCtx)
  5988  	st := &http2stream{
  5989  		sc:        sc,
  5990  		id:        id,
  5991  		state:     state,
  5992  		ctx:       ctx,
  5993  		cancelCtx: cancelCtx,
  5994  	}
  5995  	st.cw.Init()
  5996  	st.flow.conn = &sc.flow // link to conn-level counter
  5997  	st.flow.add(sc.initialStreamSendWindowSize)
  5998  	st.inflow.init(sc.srv.initialStreamRecvWindowSize())
  5999  	if sc.hs.WriteTimeout > 0 {
  6000  		st.writeDeadline = sc.srv.afterFunc(sc.hs.WriteTimeout, st.onWriteTimeout)
  6001  	}
  6002  
  6003  	sc.streams[id] = st
  6004  	sc.writeSched.OpenStream(st.id, http2OpenStreamOptions{PusherID: pusherID})
  6005  	if st.isPushed() {
  6006  		sc.curPushedStreams++
  6007  	} else {
  6008  		sc.curClientStreams++
  6009  	}
  6010  	if sc.curOpenStreams() == 1 {
  6011  		sc.setConnState(StateActive)
  6012  	}
  6013  
  6014  	return st
  6015  }
  6016  
  6017  func (sc *http2serverConn) newWriterAndRequest(st *http2stream, f *http2MetaHeadersFrame) (*http2responseWriter, *Request, error) {
  6018  	sc.serveG.check()
  6019  
  6020  	rp := http2requestParam{
  6021  		method:    f.PseudoValue("method"),
  6022  		scheme:    f.PseudoValue("scheme"),
  6023  		authority: f.PseudoValue("authority"),
  6024  		path:      f.PseudoValue("path"),
  6025  	}
  6026  
  6027  	isConnect := rp.method == "CONNECT"
  6028  	if isConnect {
  6029  		if rp.path != "" || rp.scheme != "" || rp.authority == "" {
  6030  			return nil, nil, sc.countError("bad_connect", http2streamError(f.StreamID, http2ErrCodeProtocol))
  6031  		}
  6032  	} else if rp.method == "" || rp.path == "" || (rp.scheme != "https" && rp.scheme != "http") {
  6033  		// See 8.1.2.6 Malformed Requests and Responses:
  6034  		//
  6035  		// Malformed requests or responses that are detected
  6036  		// MUST be treated as a stream error (Section 5.4.2)
  6037  		// of type PROTOCOL_ERROR."
  6038  		//
  6039  		// 8.1.2.3 Request Pseudo-Header Fields
  6040  		// "All HTTP/2 requests MUST include exactly one valid
  6041  		// value for the :method, :scheme, and :path
  6042  		// pseudo-header fields"
  6043  		return nil, nil, sc.countError("bad_path_method", http2streamError(f.StreamID, http2ErrCodeProtocol))
  6044  	}
  6045  
  6046  	rp.header = make(Header)
  6047  	for _, hf := range f.RegularFields() {
  6048  		rp.header.Add(sc.canonicalHeader(hf.Name), hf.Value)
  6049  	}
  6050  	if rp.authority == "" {
  6051  		rp.authority = rp.header.Get("Host")
  6052  	}
  6053  
  6054  	rw, req, err := sc.newWriterAndRequestNoBody(st, rp)
  6055  	if err != nil {
  6056  		return nil, nil, err
  6057  	}
  6058  	bodyOpen := !f.StreamEnded()
  6059  	if bodyOpen {
  6060  		if vv, ok := rp.header["Content-Length"]; ok {
  6061  			if cl, err := strconv.ParseUint(vv[0], 10, 63); err == nil {
  6062  				req.ContentLength = int64(cl)
  6063  			} else {
  6064  				req.ContentLength = 0
  6065  			}
  6066  		} else {
  6067  			req.ContentLength = -1
  6068  		}
  6069  		req.Body.(*http2requestBody).pipe = &http2pipe{
  6070  			b: &http2dataBuffer{expected: req.ContentLength},
  6071  		}
  6072  	}
  6073  	return rw, req, nil
  6074  }
  6075  
  6076  type http2requestParam struct {
  6077  	method                  string
  6078  	scheme, authority, path string
  6079  	header                  Header
  6080  }
  6081  
  6082  func (sc *http2serverConn) newWriterAndRequestNoBody(st *http2stream, rp http2requestParam) (*http2responseWriter, *Request, error) {
  6083  	sc.serveG.check()
  6084  
  6085  	var tlsState *tls.ConnectionState // nil if not scheme https
  6086  	if rp.scheme == "https" {
  6087  		tlsState = sc.tlsState
  6088  	}
  6089  
  6090  	needsContinue := httpguts.HeaderValuesContainsToken(rp.header["Expect"], "100-continue")
  6091  	if needsContinue {
  6092  		rp.header.Del("Expect")
  6093  	}
  6094  	// Merge Cookie headers into one "; "-delimited value.
  6095  	if cookies := rp.header["Cookie"]; len(cookies) > 1 {
  6096  		rp.header.Set("Cookie", strings.Join(cookies, "; "))
  6097  	}
  6098  
  6099  	// Setup Trailers
  6100  	var trailer Header
  6101  	for _, v := range rp.header["Trailer"] {
  6102  		for _, key := range strings.Split(v, ",") {
  6103  			key = CanonicalHeaderKey(textproto.TrimString(key))
  6104  			switch key {
  6105  			case "Transfer-Encoding", "Trailer", "Content-Length":
  6106  				// Bogus. (copy of http1 rules)
  6107  				// Ignore.
  6108  			default:
  6109  				if trailer == nil {
  6110  					trailer = make(Header)
  6111  				}
  6112  				trailer[key] = nil
  6113  			}
  6114  		}
  6115  	}
  6116  	delete(rp.header, "Trailer")
  6117  
  6118  	var url_ *url.URL
  6119  	var requestURI string
  6120  	if rp.method == "CONNECT" {
  6121  		url_ = &url.URL{Host: rp.authority}
  6122  		requestURI = rp.authority // mimic HTTP/1 server behavior
  6123  	} else {
  6124  		var err error
  6125  		url_, err = url.ParseRequestURI(rp.path)
  6126  		if err != nil {
  6127  			return nil, nil, sc.countError("bad_path", http2streamError(st.id, http2ErrCodeProtocol))
  6128  		}
  6129  		requestURI = rp.path
  6130  	}
  6131  
  6132  	body := &http2requestBody{
  6133  		conn:          sc,
  6134  		stream:        st,
  6135  		needsContinue: needsContinue,
  6136  	}
  6137  	req := &Request{
  6138  		Method:     rp.method,
  6139  		URL:        url_,
  6140  		RemoteAddr: sc.remoteAddrStr,
  6141  		Header:     rp.header,
  6142  		RequestURI: requestURI,
  6143  		Proto:      "HTTP/2.0",
  6144  		ProtoMajor: 2,
  6145  		ProtoMinor: 0,
  6146  		TLS:        tlsState,
  6147  		Host:       rp.authority,
  6148  		Body:       body,
  6149  		Trailer:    trailer,
  6150  	}
  6151  	req = req.WithContext(st.ctx)
  6152  
  6153  	rw := sc.newResponseWriter(st, req)
  6154  	return rw, req, nil
  6155  }
  6156  
  6157  func (sc *http2serverConn) newResponseWriter(st *http2stream, req *Request) *http2responseWriter {
  6158  	rws := http2responseWriterStatePool.Get().(*http2responseWriterState)
  6159  	bwSave := rws.bw
  6160  	*rws = http2responseWriterState{} // zero all the fields
  6161  	rws.conn = sc
  6162  	rws.bw = bwSave
  6163  	rws.bw.Reset(http2chunkWriter{rws})
  6164  	rws.stream = st
  6165  	rws.req = req
  6166  	return &http2responseWriter{rws: rws}
  6167  }
  6168  
  6169  type http2unstartedHandler struct {
  6170  	streamID uint32
  6171  	rw       *http2responseWriter
  6172  	req      *Request
  6173  	handler  func(ResponseWriter, *Request)
  6174  }
  6175  
  6176  // scheduleHandler starts a handler goroutine,
  6177  // or schedules one to start as soon as an existing handler finishes.
  6178  func (sc *http2serverConn) scheduleHandler(streamID uint32, rw *http2responseWriter, req *Request, handler func(ResponseWriter, *Request)) error {
  6179  	sc.serveG.check()
  6180  	maxHandlers := sc.advMaxStreams
  6181  	if sc.curHandlers < maxHandlers {
  6182  		sc.curHandlers++
  6183  		go sc.runHandler(rw, req, handler)
  6184  		return nil
  6185  	}
  6186  	if len(sc.unstartedHandlers) > int(4*sc.advMaxStreams) {
  6187  		return sc.countError("too_many_early_resets", http2ConnectionError(http2ErrCodeEnhanceYourCalm))
  6188  	}
  6189  	sc.unstartedHandlers = append(sc.unstartedHandlers, http2unstartedHandler{
  6190  		streamID: streamID,
  6191  		rw:       rw,
  6192  		req:      req,
  6193  		handler:  handler,
  6194  	})
  6195  	return nil
  6196  }
  6197  
  6198  func (sc *http2serverConn) handlerDone() {
  6199  	sc.serveG.check()
  6200  	sc.curHandlers--
  6201  	i := 0
  6202  	maxHandlers := sc.advMaxStreams
  6203  	for ; i < len(sc.unstartedHandlers); i++ {
  6204  		u := sc.unstartedHandlers[i]
  6205  		if sc.streams[u.streamID] == nil {
  6206  			// This stream was reset before its goroutine had a chance to start.
  6207  			continue
  6208  		}
  6209  		if sc.curHandlers >= maxHandlers {
  6210  			break
  6211  		}
  6212  		sc.curHandlers++
  6213  		go sc.runHandler(u.rw, u.req, u.handler)
  6214  		sc.unstartedHandlers[i] = http2unstartedHandler{} // don't retain references
  6215  	}
  6216  	sc.unstartedHandlers = sc.unstartedHandlers[i:]
  6217  	if len(sc.unstartedHandlers) == 0 {
  6218  		sc.unstartedHandlers = nil
  6219  	}
  6220  }
  6221  
  6222  // Run on its own goroutine.
  6223  func (sc *http2serverConn) runHandler(rw *http2responseWriter, req *Request, handler func(ResponseWriter, *Request)) {
  6224  	sc.srv.markNewGoroutine()
  6225  	defer sc.sendServeMsg(http2handlerDoneMsg)
  6226  	didPanic := true
  6227  	defer func() {
  6228  		rw.rws.stream.cancelCtx()
  6229  		if req.MultipartForm != nil {
  6230  			req.MultipartForm.RemoveAll()
  6231  		}
  6232  		if didPanic {
  6233  			e := recover()
  6234  			sc.writeFrameFromHandler(http2FrameWriteRequest{
  6235  				write:  http2handlerPanicRST{rw.rws.stream.id},
  6236  				stream: rw.rws.stream,
  6237  			})
  6238  			// Same as net/http:
  6239  			if e != nil && e != ErrAbortHandler {
  6240  				const size = 64 << 10
  6241  				buf := make([]byte, size)
  6242  				buf = buf[:runtime.Stack(buf, false)]
  6243  				sc.logf("http2: panic serving %v: %v\n%s", sc.conn.RemoteAddr(), e, buf)
  6244  			}
  6245  			return
  6246  		}
  6247  		rw.handlerDone()
  6248  	}()
  6249  	handler(rw, req)
  6250  	didPanic = false
  6251  }
  6252  
  6253  func http2handleHeaderListTooLong(w ResponseWriter, r *Request) {
  6254  	// 10.5.1 Limits on Header Block Size:
  6255  	// .. "A server that receives a larger header block than it is
  6256  	// willing to handle can send an HTTP 431 (Request Header Fields Too
  6257  	// Large) status code"
  6258  	const statusRequestHeaderFieldsTooLarge = 431 // only in Go 1.6+
  6259  	w.WriteHeader(statusRequestHeaderFieldsTooLarge)
  6260  	io.WriteString(w, "<h1>HTTP Error 431</h1><p>Request Header Field(s) Too Large</p>")
  6261  }
  6262  
  6263  // called from handler goroutines.
  6264  // h may be nil.
  6265  func (sc *http2serverConn) writeHeaders(st *http2stream, headerData *http2writeResHeaders) error {
  6266  	sc.serveG.checkNotOn() // NOT on
  6267  	var errc chan error
  6268  	if headerData.h != nil {
  6269  		// If there's a header map (which we don't own), so we have to block on
  6270  		// waiting for this frame to be written, so an http.Flush mid-handler
  6271  		// writes out the correct value of keys, before a handler later potentially
  6272  		// mutates it.
  6273  		errc = http2errChanPool.Get().(chan error)
  6274  	}
  6275  	if err := sc.writeFrameFromHandler(http2FrameWriteRequest{
  6276  		write:  headerData,
  6277  		stream: st,
  6278  		done:   errc,
  6279  	}); err != nil {
  6280  		return err
  6281  	}
  6282  	if errc != nil {
  6283  		select {
  6284  		case err := <-errc:
  6285  			http2errChanPool.Put(errc)
  6286  			return err
  6287  		case <-sc.doneServing:
  6288  			return http2errClientDisconnected
  6289  		case <-st.cw:
  6290  			return http2errStreamClosed
  6291  		}
  6292  	}
  6293  	return nil
  6294  }
  6295  
  6296  // called from handler goroutines.
  6297  func (sc *http2serverConn) write100ContinueHeaders(st *http2stream) {
  6298  	sc.writeFrameFromHandler(http2FrameWriteRequest{
  6299  		write:  http2write100ContinueHeadersFrame{st.id},
  6300  		stream: st,
  6301  	})
  6302  }
  6303  
  6304  // A bodyReadMsg tells the server loop that the http.Handler read n
  6305  // bytes of the DATA from the client on the given stream.
  6306  type http2bodyReadMsg struct {
  6307  	st *http2stream
  6308  	n  int
  6309  }
  6310  
  6311  // called from handler goroutines.
  6312  // Notes that the handler for the given stream ID read n bytes of its body
  6313  // and schedules flow control tokens to be sent.
  6314  func (sc *http2serverConn) noteBodyReadFromHandler(st *http2stream, n int, err error) {
  6315  	sc.serveG.checkNotOn() // NOT on
  6316  	if n > 0 {
  6317  		select {
  6318  		case sc.bodyReadCh <- http2bodyReadMsg{st, n}:
  6319  		case <-sc.doneServing:
  6320  		}
  6321  	}
  6322  }
  6323  
  6324  func (sc *http2serverConn) noteBodyRead(st *http2stream, n int) {
  6325  	sc.serveG.check()
  6326  	sc.sendWindowUpdate(nil, n) // conn-level
  6327  	if st.state != http2stateHalfClosedRemote && st.state != http2stateClosed {
  6328  		// Don't send this WINDOW_UPDATE if the stream is closed
  6329  		// remotely.
  6330  		sc.sendWindowUpdate(st, n)
  6331  	}
  6332  }
  6333  
  6334  // st may be nil for conn-level
  6335  func (sc *http2serverConn) sendWindowUpdate32(st *http2stream, n int32) {
  6336  	sc.sendWindowUpdate(st, int(n))
  6337  }
  6338  
  6339  // st may be nil for conn-level
  6340  func (sc *http2serverConn) sendWindowUpdate(st *http2stream, n int) {
  6341  	sc.serveG.check()
  6342  	var streamID uint32
  6343  	var send int32
  6344  	if st == nil {
  6345  		send = sc.inflow.add(n)
  6346  	} else {
  6347  		streamID = st.id
  6348  		send = st.inflow.add(n)
  6349  	}
  6350  	if send == 0 {
  6351  		return
  6352  	}
  6353  	sc.writeFrame(http2FrameWriteRequest{
  6354  		write:  http2writeWindowUpdate{streamID: streamID, n: uint32(send)},
  6355  		stream: st,
  6356  	})
  6357  }
  6358  
  6359  // requestBody is the Handler's Request.Body type.
  6360  // Read and Close may be called concurrently.
  6361  type http2requestBody struct {
  6362  	_             http2incomparable
  6363  	stream        *http2stream
  6364  	conn          *http2serverConn
  6365  	closeOnce     sync.Once  // for use by Close only
  6366  	sawEOF        bool       // for use by Read only
  6367  	pipe          *http2pipe // non-nil if we have an HTTP entity message body
  6368  	needsContinue bool       // need to send a 100-continue
  6369  }
  6370  
  6371  func (b *http2requestBody) Close() error {
  6372  	b.closeOnce.Do(func() {
  6373  		if b.pipe != nil {
  6374  			b.pipe.BreakWithError(http2errClosedBody)
  6375  		}
  6376  	})
  6377  	return nil
  6378  }
  6379  
  6380  func (b *http2requestBody) Read(p []byte) (n int, err error) {
  6381  	if b.needsContinue {
  6382  		b.needsContinue = false
  6383  		b.conn.write100ContinueHeaders(b.stream)
  6384  	}
  6385  	if b.pipe == nil || b.sawEOF {
  6386  		return 0, io.EOF
  6387  	}
  6388  	n, err = b.pipe.Read(p)
  6389  	if err == io.EOF {
  6390  		b.sawEOF = true
  6391  	}
  6392  	if b.conn == nil && http2inTests {
  6393  		return
  6394  	}
  6395  	b.conn.noteBodyReadFromHandler(b.stream, n, err)
  6396  	return
  6397  }
  6398  
  6399  // responseWriter is the http.ResponseWriter implementation. It's
  6400  // intentionally small (1 pointer wide) to minimize garbage. The
  6401  // responseWriterState pointer inside is zeroed at the end of a
  6402  // request (in handlerDone) and calls on the responseWriter thereafter
  6403  // simply crash (caller's mistake), but the much larger responseWriterState
  6404  // and buffers are reused between multiple requests.
  6405  type http2responseWriter struct {
  6406  	rws *http2responseWriterState
  6407  }
  6408  
  6409  // Optional http.ResponseWriter interfaces implemented.
  6410  var (
  6411  	_ CloseNotifier     = (*http2responseWriter)(nil)
  6412  	_ Flusher           = (*http2responseWriter)(nil)
  6413  	_ http2stringWriter = (*http2responseWriter)(nil)
  6414  )
  6415  
  6416  type http2responseWriterState struct {
  6417  	// immutable within a request:
  6418  	stream *http2stream
  6419  	req    *Request
  6420  	conn   *http2serverConn
  6421  
  6422  	// TODO: adjust buffer writing sizes based on server config, frame size updates from peer, etc
  6423  	bw *bufio.Writer // writing to a chunkWriter{this *responseWriterState}
  6424  
  6425  	// mutated by http.Handler goroutine:
  6426  	handlerHeader Header   // nil until called
  6427  	snapHeader    Header   // snapshot of handlerHeader at WriteHeader time
  6428  	trailers      []string // set in writeChunk
  6429  	status        int      // status code passed to WriteHeader
  6430  	wroteHeader   bool     // WriteHeader called (explicitly or implicitly). Not necessarily sent to user yet.
  6431  	sentHeader    bool     // have we sent the header frame?
  6432  	handlerDone   bool     // handler has finished
  6433  
  6434  	sentContentLen int64 // non-zero if handler set a Content-Length header
  6435  	wroteBytes     int64
  6436  
  6437  	closeNotifierMu sync.Mutex // guards closeNotifierCh
  6438  	closeNotifierCh chan bool  // nil until first used
  6439  }
  6440  
  6441  type http2chunkWriter struct{ rws *http2responseWriterState }
  6442  
  6443  func (cw http2chunkWriter) Write(p []byte) (n int, err error) {
  6444  	n, err = cw.rws.writeChunk(p)
  6445  	if err == http2errStreamClosed {
  6446  		// If writing failed because the stream has been closed,
  6447  		// return the reason it was closed.
  6448  		err = cw.rws.stream.closeErr
  6449  	}
  6450  	return n, err
  6451  }
  6452  
  6453  func (rws *http2responseWriterState) hasTrailers() bool { return len(rws.trailers) > 0 }
  6454  
  6455  func (rws *http2responseWriterState) hasNonemptyTrailers() bool {
  6456  	for _, trailer := range rws.trailers {
  6457  		if _, ok := rws.handlerHeader[trailer]; ok {
  6458  			return true
  6459  		}
  6460  	}
  6461  	return false
  6462  }
  6463  
  6464  // declareTrailer is called for each Trailer header when the
  6465  // response header is written. It notes that a header will need to be
  6466  // written in the trailers at the end of the response.
  6467  func (rws *http2responseWriterState) declareTrailer(k string) {
  6468  	k = CanonicalHeaderKey(k)
  6469  	if !httpguts.ValidTrailerHeader(k) {
  6470  		// Forbidden by RFC 7230, section 4.1.2.
  6471  		rws.conn.logf("ignoring invalid trailer %q", k)
  6472  		return
  6473  	}
  6474  	if !http2strSliceContains(rws.trailers, k) {
  6475  		rws.trailers = append(rws.trailers, k)
  6476  	}
  6477  }
  6478  
  6479  // writeChunk writes chunks from the bufio.Writer. But because
  6480  // bufio.Writer may bypass its chunking, sometimes p may be
  6481  // arbitrarily large.
  6482  //
  6483  // writeChunk is also responsible (on the first chunk) for sending the
  6484  // HEADER response.
  6485  func (rws *http2responseWriterState) writeChunk(p []byte) (n int, err error) {
  6486  	if !rws.wroteHeader {
  6487  		rws.writeHeader(200)
  6488  	}
  6489  
  6490  	if rws.handlerDone {
  6491  		rws.promoteUndeclaredTrailers()
  6492  	}
  6493  
  6494  	isHeadResp := rws.req.Method == "HEAD"
  6495  	if !rws.sentHeader {
  6496  		rws.sentHeader = true
  6497  		var ctype, clen string
  6498  		if clen = rws.snapHeader.Get("Content-Length"); clen != "" {
  6499  			rws.snapHeader.Del("Content-Length")
  6500  			if cl, err := strconv.ParseUint(clen, 10, 63); err == nil {
  6501  				rws.sentContentLen = int64(cl)
  6502  			} else {
  6503  				clen = ""
  6504  			}
  6505  		}
  6506  		_, hasContentLength := rws.snapHeader["Content-Length"]
  6507  		if !hasContentLength && clen == "" && rws.handlerDone && http2bodyAllowedForStatus(rws.status) && (len(p) > 0 || !isHeadResp) {
  6508  			clen = strconv.Itoa(len(p))
  6509  		}
  6510  		_, hasContentType := rws.snapHeader["Content-Type"]
  6511  		// If the Content-Encoding is non-blank, we shouldn't
  6512  		// sniff the body. See Issue golang.org/issue/31753.
  6513  		ce := rws.snapHeader.Get("Content-Encoding")
  6514  		hasCE := len(ce) > 0
  6515  		if !hasCE && !hasContentType && http2bodyAllowedForStatus(rws.status) && len(p) > 0 {
  6516  			ctype = DetectContentType(p)
  6517  		}
  6518  		var date string
  6519  		if _, ok := rws.snapHeader["Date"]; !ok {
  6520  			// TODO(bradfitz): be faster here, like net/http? measure.
  6521  			date = rws.conn.srv.now().UTC().Format(TimeFormat)
  6522  		}
  6523  
  6524  		for _, v := range rws.snapHeader["Trailer"] {
  6525  			http2foreachHeaderElement(v, rws.declareTrailer)
  6526  		}
  6527  
  6528  		// "Connection" headers aren't allowed in HTTP/2 (RFC 7540, 8.1.2.2),
  6529  		// but respect "Connection" == "close" to mean sending a GOAWAY and tearing
  6530  		// down the TCP connection when idle, like we do for HTTP/1.
  6531  		// TODO: remove more Connection-specific header fields here, in addition
  6532  		// to "Connection".
  6533  		if _, ok := rws.snapHeader["Connection"]; ok {
  6534  			v := rws.snapHeader.Get("Connection")
  6535  			delete(rws.snapHeader, "Connection")
  6536  			if v == "close" {
  6537  				rws.conn.startGracefulShutdown()
  6538  			}
  6539  		}
  6540  
  6541  		endStream := (rws.handlerDone && !rws.hasTrailers() && len(p) == 0) || isHeadResp
  6542  		err = rws.conn.writeHeaders(rws.stream, &http2writeResHeaders{
  6543  			streamID:      rws.stream.id,
  6544  			httpResCode:   rws.status,
  6545  			h:             rws.snapHeader,
  6546  			endStream:     endStream,
  6547  			contentType:   ctype,
  6548  			contentLength: clen,
  6549  			date:          date,
  6550  		})
  6551  		if err != nil {
  6552  			return 0, err
  6553  		}
  6554  		if endStream {
  6555  			return 0, nil
  6556  		}
  6557  	}
  6558  	if isHeadResp {
  6559  		return len(p), nil
  6560  	}
  6561  	if len(p) == 0 && !rws.handlerDone {
  6562  		return 0, nil
  6563  	}
  6564  
  6565  	// only send trailers if they have actually been defined by the
  6566  	// server handler.
  6567  	hasNonemptyTrailers := rws.hasNonemptyTrailers()
  6568  	endStream := rws.handlerDone && !hasNonemptyTrailers
  6569  	if len(p) > 0 || endStream {
  6570  		// only send a 0 byte DATA frame if we're ending the stream.
  6571  		if err := rws.conn.writeDataFromHandler(rws.stream, p, endStream); err != nil {
  6572  			return 0, err
  6573  		}
  6574  	}
  6575  
  6576  	if rws.handlerDone && hasNonemptyTrailers {
  6577  		err = rws.conn.writeHeaders(rws.stream, &http2writeResHeaders{
  6578  			streamID:  rws.stream.id,
  6579  			h:         rws.handlerHeader,
  6580  			trailers:  rws.trailers,
  6581  			endStream: true,
  6582  		})
  6583  		return len(p), err
  6584  	}
  6585  	return len(p), nil
  6586  }
  6587  
  6588  // TrailerPrefix is a magic prefix for ResponseWriter.Header map keys
  6589  // that, if present, signals that the map entry is actually for
  6590  // the response trailers, and not the response headers. The prefix
  6591  // is stripped after the ServeHTTP call finishes and the values are
  6592  // sent in the trailers.
  6593  //
  6594  // This mechanism is intended only for trailers that are not known
  6595  // prior to the headers being written. If the set of trailers is fixed
  6596  // or known before the header is written, the normal Go trailers mechanism
  6597  // is preferred:
  6598  //
  6599  //	https://golang.org/pkg/net/http/#ResponseWriter
  6600  //	https://golang.org/pkg/net/http/#example_ResponseWriter_trailers
  6601  const http2TrailerPrefix = "Trailer:"
  6602  
  6603  // promoteUndeclaredTrailers permits http.Handlers to set trailers
  6604  // after the header has already been flushed. Because the Go
  6605  // ResponseWriter interface has no way to set Trailers (only the
  6606  // Header), and because we didn't want to expand the ResponseWriter
  6607  // interface, and because nobody used trailers, and because RFC 7230
  6608  // says you SHOULD (but not must) predeclare any trailers in the
  6609  // header, the official ResponseWriter rules said trailers in Go must
  6610  // be predeclared, and then we reuse the same ResponseWriter.Header()
  6611  // map to mean both Headers and Trailers. When it's time to write the
  6612  // Trailers, we pick out the fields of Headers that were declared as
  6613  // trailers. That worked for a while, until we found the first major
  6614  // user of Trailers in the wild: gRPC (using them only over http2),
  6615  // and gRPC libraries permit setting trailers mid-stream without
  6616  // predeclaring them. So: change of plans. We still permit the old
  6617  // way, but we also permit this hack: if a Header() key begins with
  6618  // "Trailer:", the suffix of that key is a Trailer. Because ':' is an
  6619  // invalid token byte anyway, there is no ambiguity. (And it's already
  6620  // filtered out) It's mildly hacky, but not terrible.
  6621  //
  6622  // This method runs after the Handler is done and promotes any Header
  6623  // fields to be trailers.
  6624  func (rws *http2responseWriterState) promoteUndeclaredTrailers() {
  6625  	for k, vv := range rws.handlerHeader {
  6626  		if !strings.HasPrefix(k, http2TrailerPrefix) {
  6627  			continue
  6628  		}
  6629  		trailerKey := strings.TrimPrefix(k, http2TrailerPrefix)
  6630  		rws.declareTrailer(trailerKey)
  6631  		rws.handlerHeader[CanonicalHeaderKey(trailerKey)] = vv
  6632  	}
  6633  
  6634  	if len(rws.trailers) > 1 {
  6635  		sorter := http2sorterPool.Get().(*http2sorter)
  6636  		sorter.SortStrings(rws.trailers)
  6637  		http2sorterPool.Put(sorter)
  6638  	}
  6639  }
  6640  
  6641  func (w *http2responseWriter) SetReadDeadline(deadline time.Time) error {
  6642  	st := w.rws.stream
  6643  	if !deadline.IsZero() && deadline.Before(w.rws.conn.srv.now()) {
  6644  		// If we're setting a deadline in the past, reset the stream immediately
  6645  		// so writes after SetWriteDeadline returns will fail.
  6646  		st.onReadTimeout()
  6647  		return nil
  6648  	}
  6649  	w.rws.conn.sendServeMsg(func(sc *http2serverConn) {
  6650  		if st.readDeadline != nil {
  6651  			if !st.readDeadline.Stop() {
  6652  				// Deadline already exceeded, or stream has been closed.
  6653  				return
  6654  			}
  6655  		}
  6656  		if deadline.IsZero() {
  6657  			st.readDeadline = nil
  6658  		} else if st.readDeadline == nil {
  6659  			st.readDeadline = sc.srv.afterFunc(deadline.Sub(sc.srv.now()), st.onReadTimeout)
  6660  		} else {
  6661  			st.readDeadline.Reset(deadline.Sub(sc.srv.now()))
  6662  		}
  6663  	})
  6664  	return nil
  6665  }
  6666  
  6667  func (w *http2responseWriter) SetWriteDeadline(deadline time.Time) error {
  6668  	st := w.rws.stream
  6669  	if !deadline.IsZero() && deadline.Before(w.rws.conn.srv.now()) {
  6670  		// If we're setting a deadline in the past, reset the stream immediately
  6671  		// so writes after SetWriteDeadline returns will fail.
  6672  		st.onWriteTimeout()
  6673  		return nil
  6674  	}
  6675  	w.rws.conn.sendServeMsg(func(sc *http2serverConn) {
  6676  		if st.writeDeadline != nil {
  6677  			if !st.writeDeadline.Stop() {
  6678  				// Deadline already exceeded, or stream has been closed.
  6679  				return
  6680  			}
  6681  		}
  6682  		if deadline.IsZero() {
  6683  			st.writeDeadline = nil
  6684  		} else if st.writeDeadline == nil {
  6685  			st.writeDeadline = sc.srv.afterFunc(deadline.Sub(sc.srv.now()), st.onWriteTimeout)
  6686  		} else {
  6687  			st.writeDeadline.Reset(deadline.Sub(sc.srv.now()))
  6688  		}
  6689  	})
  6690  	return nil
  6691  }
  6692  
  6693  func (w *http2responseWriter) Flush() {
  6694  	w.FlushError()
  6695  }
  6696  
  6697  func (w *http2responseWriter) FlushError() error {
  6698  	rws := w.rws
  6699  	if rws == nil {
  6700  		panic("Header called after Handler finished")
  6701  	}
  6702  	var err error
  6703  	if rws.bw.Buffered() > 0 {
  6704  		err = rws.bw.Flush()
  6705  	} else {
  6706  		// The bufio.Writer won't call chunkWriter.Write
  6707  		// (writeChunk with zero bytes), so we have to do it
  6708  		// ourselves to force the HTTP response header and/or
  6709  		// final DATA frame (with END_STREAM) to be sent.
  6710  		_, err = http2chunkWriter{rws}.Write(nil)
  6711  		if err == nil {
  6712  			select {
  6713  			case <-rws.stream.cw:
  6714  				err = rws.stream.closeErr
  6715  			default:
  6716  			}
  6717  		}
  6718  	}
  6719  	return err
  6720  }
  6721  
  6722  func (w *http2responseWriter) CloseNotify() <-chan bool {
  6723  	rws := w.rws
  6724  	if rws == nil {
  6725  		panic("CloseNotify called after Handler finished")
  6726  	}
  6727  	rws.closeNotifierMu.Lock()
  6728  	ch := rws.closeNotifierCh
  6729  	if ch == nil {
  6730  		ch = make(chan bool, 1)
  6731  		rws.closeNotifierCh = ch
  6732  		cw := rws.stream.cw
  6733  		go func() {
  6734  			cw.Wait() // wait for close
  6735  			ch <- true
  6736  		}()
  6737  	}
  6738  	rws.closeNotifierMu.Unlock()
  6739  	return ch
  6740  }
  6741  
  6742  func (w *http2responseWriter) Header() Header {
  6743  	rws := w.rws
  6744  	if rws == nil {
  6745  		panic("Header called after Handler finished")
  6746  	}
  6747  	if rws.handlerHeader == nil {
  6748  		rws.handlerHeader = make(Header)
  6749  	}
  6750  	return rws.handlerHeader
  6751  }
  6752  
  6753  // checkWriteHeaderCode is a copy of net/http's checkWriteHeaderCode.
  6754  func http2checkWriteHeaderCode(code int) {
  6755  	// Issue 22880: require valid WriteHeader status codes.
  6756  	// For now we only enforce that it's three digits.
  6757  	// In the future we might block things over 599 (600 and above aren't defined
  6758  	// at http://httpwg.org/specs/rfc7231.html#status.codes).
  6759  	// But for now any three digits.
  6760  	//
  6761  	// We used to send "HTTP/1.1 000 0" on the wire in responses but there's
  6762  	// no equivalent bogus thing we can realistically send in HTTP/2,
  6763  	// so we'll consistently panic instead and help people find their bugs
  6764  	// early. (We can't return an error from WriteHeader even if we wanted to.)
  6765  	if code < 100 || code > 999 {
  6766  		panic(fmt.Sprintf("invalid WriteHeader code %v", code))
  6767  	}
  6768  }
  6769  
  6770  func (w *http2responseWriter) WriteHeader(code int) {
  6771  	rws := w.rws
  6772  	if rws == nil {
  6773  		panic("WriteHeader called after Handler finished")
  6774  	}
  6775  	rws.writeHeader(code)
  6776  }
  6777  
  6778  func (rws *http2responseWriterState) writeHeader(code int) {
  6779  	if rws.wroteHeader {
  6780  		return
  6781  	}
  6782  
  6783  	http2checkWriteHeaderCode(code)
  6784  
  6785  	// Handle informational headers
  6786  	if code >= 100 && code <= 199 {
  6787  		// Per RFC 8297 we must not clear the current header map
  6788  		h := rws.handlerHeader
  6789  
  6790  		_, cl := h["Content-Length"]
  6791  		_, te := h["Transfer-Encoding"]
  6792  		if cl || te {
  6793  			h = h.Clone()
  6794  			h.Del("Content-Length")
  6795  			h.Del("Transfer-Encoding")
  6796  		}
  6797  
  6798  		rws.conn.writeHeaders(rws.stream, &http2writeResHeaders{
  6799  			streamID:    rws.stream.id,
  6800  			httpResCode: code,
  6801  			h:           h,
  6802  			endStream:   rws.handlerDone && !rws.hasTrailers(),
  6803  		})
  6804  
  6805  		return
  6806  	}
  6807  
  6808  	rws.wroteHeader = true
  6809  	rws.status = code
  6810  	if len(rws.handlerHeader) > 0 {
  6811  		rws.snapHeader = http2cloneHeader(rws.handlerHeader)
  6812  	}
  6813  }
  6814  
  6815  func http2cloneHeader(h Header) Header {
  6816  	h2 := make(Header, len(h))
  6817  	for k, vv := range h {
  6818  		vv2 := make([]string, len(vv))
  6819  		copy(vv2, vv)
  6820  		h2[k] = vv2
  6821  	}
  6822  	return h2
  6823  }
  6824  
  6825  // The Life Of A Write is like this:
  6826  //
  6827  // * Handler calls w.Write or w.WriteString ->
  6828  // * -> rws.bw (*bufio.Writer) ->
  6829  // * (Handler might call Flush)
  6830  // * -> chunkWriter{rws}
  6831  // * -> responseWriterState.writeChunk(p []byte)
  6832  // * -> responseWriterState.writeChunk (most of the magic; see comment there)
  6833  func (w *http2responseWriter) Write(p []byte) (n int, err error) {
  6834  	return w.write(len(p), p, "")
  6835  }
  6836  
  6837  func (w *http2responseWriter) WriteString(s string) (n int, err error) {
  6838  	return w.write(len(s), nil, s)
  6839  }
  6840  
  6841  // either dataB or dataS is non-zero.
  6842  func (w *http2responseWriter) write(lenData int, dataB []byte, dataS string) (n int, err error) {
  6843  	rws := w.rws
  6844  	if rws == nil {
  6845  		panic("Write called after Handler finished")
  6846  	}
  6847  	if !rws.wroteHeader {
  6848  		w.WriteHeader(200)
  6849  	}
  6850  	if !http2bodyAllowedForStatus(rws.status) {
  6851  		return 0, ErrBodyNotAllowed
  6852  	}
  6853  	rws.wroteBytes += int64(len(dataB)) + int64(len(dataS)) // only one can be set
  6854  	if rws.sentContentLen != 0 && rws.wroteBytes > rws.sentContentLen {
  6855  		// TODO: send a RST_STREAM
  6856  		return 0, errors.New("http2: handler wrote more than declared Content-Length")
  6857  	}
  6858  
  6859  	if dataB != nil {
  6860  		return rws.bw.Write(dataB)
  6861  	} else {
  6862  		return rws.bw.WriteString(dataS)
  6863  	}
  6864  }
  6865  
  6866  func (w *http2responseWriter) handlerDone() {
  6867  	rws := w.rws
  6868  	rws.handlerDone = true
  6869  	w.Flush()
  6870  	w.rws = nil
  6871  	http2responseWriterStatePool.Put(rws)
  6872  }
  6873  
  6874  // Push errors.
  6875  var (
  6876  	http2ErrRecursivePush    = errors.New("http2: recursive push not allowed")
  6877  	http2ErrPushLimitReached = errors.New("http2: push would exceed peer's SETTINGS_MAX_CONCURRENT_STREAMS")
  6878  )
  6879  
  6880  var _ Pusher = (*http2responseWriter)(nil)
  6881  
  6882  func (w *http2responseWriter) Push(target string, opts *PushOptions) error {
  6883  	st := w.rws.stream
  6884  	sc := st.sc
  6885  	sc.serveG.checkNotOn()
  6886  
  6887  	// No recursive pushes: "PUSH_PROMISE frames MUST only be sent on a peer-initiated stream."
  6888  	// http://tools.ietf.org/html/rfc7540#section-6.6
  6889  	if st.isPushed() {
  6890  		return http2ErrRecursivePush
  6891  	}
  6892  
  6893  	if opts == nil {
  6894  		opts = new(PushOptions)
  6895  	}
  6896  
  6897  	// Default options.
  6898  	if opts.Method == "" {
  6899  		opts.Method = "GET"
  6900  	}
  6901  	if opts.Header == nil {
  6902  		opts.Header = Header{}
  6903  	}
  6904  	wantScheme := "http"
  6905  	if w.rws.req.TLS != nil {
  6906  		wantScheme = "https"
  6907  	}
  6908  
  6909  	// Validate the request.
  6910  	u, err := url.Parse(target)
  6911  	if err != nil {
  6912  		return err
  6913  	}
  6914  	if u.Scheme == "" {
  6915  		if !strings.HasPrefix(target, "/") {
  6916  			return fmt.Errorf("target must be an absolute URL or an absolute path: %q", target)
  6917  		}
  6918  		u.Scheme = wantScheme
  6919  		u.Host = w.rws.req.Host
  6920  	} else {
  6921  		if u.Scheme != wantScheme {
  6922  			return fmt.Errorf("cannot push URL with scheme %q from request with scheme %q", u.Scheme, wantScheme)
  6923  		}
  6924  		if u.Host == "" {
  6925  			return errors.New("URL must have a host")
  6926  		}
  6927  	}
  6928  	for k := range opts.Header {
  6929  		if strings.HasPrefix(k, ":") {
  6930  			return fmt.Errorf("promised request headers cannot include pseudo header %q", k)
  6931  		}
  6932  		// These headers are meaningful only if the request has a body,
  6933  		// but PUSH_PROMISE requests cannot have a body.
  6934  		// http://tools.ietf.org/html/rfc7540#section-8.2
  6935  		// Also disallow Host, since the promised URL must be absolute.
  6936  		if http2asciiEqualFold(k, "content-length") ||
  6937  			http2asciiEqualFold(k, "content-encoding") ||
  6938  			http2asciiEqualFold(k, "trailer") ||
  6939  			http2asciiEqualFold(k, "te") ||
  6940  			http2asciiEqualFold(k, "expect") ||
  6941  			http2asciiEqualFold(k, "host") {
  6942  			return fmt.Errorf("promised request headers cannot include %q", k)
  6943  		}
  6944  	}
  6945  	if err := http2checkValidHTTP2RequestHeaders(opts.Header); err != nil {
  6946  		return err
  6947  	}
  6948  
  6949  	// The RFC effectively limits promised requests to GET and HEAD:
  6950  	// "Promised requests MUST be cacheable [GET, HEAD, or POST], and MUST be safe [GET or HEAD]"
  6951  	// http://tools.ietf.org/html/rfc7540#section-8.2
  6952  	if opts.Method != "GET" && opts.Method != "HEAD" {
  6953  		return fmt.Errorf("method %q must be GET or HEAD", opts.Method)
  6954  	}
  6955  
  6956  	msg := &http2startPushRequest{
  6957  		parent: st,
  6958  		method: opts.Method,
  6959  		url:    u,
  6960  		header: http2cloneHeader(opts.Header),
  6961  		done:   http2errChanPool.Get().(chan error),
  6962  	}
  6963  
  6964  	select {
  6965  	case <-sc.doneServing:
  6966  		return http2errClientDisconnected
  6967  	case <-st.cw:
  6968  		return http2errStreamClosed
  6969  	case sc.serveMsgCh <- msg:
  6970  	}
  6971  
  6972  	select {
  6973  	case <-sc.doneServing:
  6974  		return http2errClientDisconnected
  6975  	case <-st.cw:
  6976  		return http2errStreamClosed
  6977  	case err := <-msg.done:
  6978  		http2errChanPool.Put(msg.done)
  6979  		return err
  6980  	}
  6981  }
  6982  
  6983  type http2startPushRequest struct {
  6984  	parent *http2stream
  6985  	method string
  6986  	url    *url.URL
  6987  	header Header
  6988  	done   chan error
  6989  }
  6990  
  6991  func (sc *http2serverConn) startPush(msg *http2startPushRequest) {
  6992  	sc.serveG.check()
  6993  
  6994  	// http://tools.ietf.org/html/rfc7540#section-6.6.
  6995  	// PUSH_PROMISE frames MUST only be sent on a peer-initiated stream that
  6996  	// is in either the "open" or "half-closed (remote)" state.
  6997  	if msg.parent.state != http2stateOpen && msg.parent.state != http2stateHalfClosedRemote {
  6998  		// responseWriter.Push checks that the stream is peer-initiated.
  6999  		msg.done <- http2errStreamClosed
  7000  		return
  7001  	}
  7002  
  7003  	// http://tools.ietf.org/html/rfc7540#section-6.6.
  7004  	if !sc.pushEnabled {
  7005  		msg.done <- ErrNotSupported
  7006  		return
  7007  	}
  7008  
  7009  	// PUSH_PROMISE frames must be sent in increasing order by stream ID, so
  7010  	// we allocate an ID for the promised stream lazily, when the PUSH_PROMISE
  7011  	// is written. Once the ID is allocated, we start the request handler.
  7012  	allocatePromisedID := func() (uint32, error) {
  7013  		sc.serveG.check()
  7014  
  7015  		// Check this again, just in case. Technically, we might have received
  7016  		// an updated SETTINGS by the time we got around to writing this frame.
  7017  		if !sc.pushEnabled {
  7018  			return 0, ErrNotSupported
  7019  		}
  7020  		// http://tools.ietf.org/html/rfc7540#section-6.5.2.
  7021  		if sc.curPushedStreams+1 > sc.clientMaxStreams {
  7022  			return 0, http2ErrPushLimitReached
  7023  		}
  7024  
  7025  		// http://tools.ietf.org/html/rfc7540#section-5.1.1.
  7026  		// Streams initiated by the server MUST use even-numbered identifiers.
  7027  		// A server that is unable to establish a new stream identifier can send a GOAWAY
  7028  		// frame so that the client is forced to open a new connection for new streams.
  7029  		if sc.maxPushPromiseID+2 >= 1<<31 {
  7030  			sc.startGracefulShutdownInternal()
  7031  			return 0, http2ErrPushLimitReached
  7032  		}
  7033  		sc.maxPushPromiseID += 2
  7034  		promisedID := sc.maxPushPromiseID
  7035  
  7036  		// http://tools.ietf.org/html/rfc7540#section-8.2.
  7037  		// Strictly speaking, the new stream should start in "reserved (local)", then
  7038  		// transition to "half closed (remote)" after sending the initial HEADERS, but
  7039  		// we start in "half closed (remote)" for simplicity.
  7040  		// See further comments at the definition of stateHalfClosedRemote.
  7041  		promised := sc.newStream(promisedID, msg.parent.id, http2stateHalfClosedRemote)
  7042  		rw, req, err := sc.newWriterAndRequestNoBody(promised, http2requestParam{
  7043  			method:    msg.method,
  7044  			scheme:    msg.url.Scheme,
  7045  			authority: msg.url.Host,
  7046  			path:      msg.url.RequestURI(),
  7047  			header:    http2cloneHeader(msg.header), // clone since handler runs concurrently with writing the PUSH_PROMISE
  7048  		})
  7049  		if err != nil {
  7050  			// Should not happen, since we've already validated msg.url.
  7051  			panic(fmt.Sprintf("newWriterAndRequestNoBody(%+v): %v", msg.url, err))
  7052  		}
  7053  
  7054  		sc.curHandlers++
  7055  		go sc.runHandler(rw, req, sc.handler.ServeHTTP)
  7056  		return promisedID, nil
  7057  	}
  7058  
  7059  	sc.writeFrame(http2FrameWriteRequest{
  7060  		write: &http2writePushPromise{
  7061  			streamID:           msg.parent.id,
  7062  			method:             msg.method,
  7063  			url:                msg.url,
  7064  			h:                  msg.header,
  7065  			allocatePromisedID: allocatePromisedID,
  7066  		},
  7067  		stream: msg.parent,
  7068  		done:   msg.done,
  7069  	})
  7070  }
  7071  
  7072  // foreachHeaderElement splits v according to the "#rule" construction
  7073  // in RFC 7230 section 7 and calls fn for each non-empty element.
  7074  func http2foreachHeaderElement(v string, fn func(string)) {
  7075  	v = textproto.TrimString(v)
  7076  	if v == "" {
  7077  		return
  7078  	}
  7079  	if !strings.Contains(v, ",") {
  7080  		fn(v)
  7081  		return
  7082  	}
  7083  	for _, f := range strings.Split(v, ",") {
  7084  		if f = textproto.TrimString(f); f != "" {
  7085  			fn(f)
  7086  		}
  7087  	}
  7088  }
  7089  
  7090  // From http://httpwg.org/specs/rfc7540.html#rfc.section.8.1.2.2
  7091  var http2connHeaders = []string{
  7092  	"Connection",
  7093  	"Keep-Alive",
  7094  	"Proxy-Connection",
  7095  	"Transfer-Encoding",
  7096  	"Upgrade",
  7097  }
  7098  
  7099  // checkValidHTTP2RequestHeaders checks whether h is a valid HTTP/2 request,
  7100  // per RFC 7540 Section 8.1.2.2.
  7101  // The returned error is reported to users.
  7102  func http2checkValidHTTP2RequestHeaders(h Header) error {
  7103  	for _, k := range http2connHeaders {
  7104  		if _, ok := h[k]; ok {
  7105  			return fmt.Errorf("request header %q is not valid in HTTP/2", k)
  7106  		}
  7107  	}
  7108  	te := h["Te"]
  7109  	if len(te) > 0 && (len(te) > 1 || (te[0] != "trailers" && te[0] != "")) {
  7110  		return errors.New(`request header "TE" may only be "trailers" in HTTP/2`)
  7111  	}
  7112  	return nil
  7113  }
  7114  
  7115  func http2new400Handler(err error) HandlerFunc {
  7116  	return func(w ResponseWriter, r *Request) {
  7117  		Error(w, err.Error(), StatusBadRequest)
  7118  	}
  7119  }
  7120  
  7121  // h1ServerKeepAlivesDisabled reports whether hs has its keep-alives
  7122  // disabled. See comments on h1ServerShutdownChan above for why
  7123  // the code is written this way.
  7124  func http2h1ServerKeepAlivesDisabled(hs *Server) bool {
  7125  	var x interface{} = hs
  7126  	type I interface {
  7127  		doKeepAlives() bool
  7128  	}
  7129  	if hs, ok := x.(I); ok {
  7130  		return !hs.doKeepAlives()
  7131  	}
  7132  	return false
  7133  }
  7134  
  7135  func (sc *http2serverConn) countError(name string, err error) error {
  7136  	if sc == nil || sc.srv == nil {
  7137  		return err
  7138  	}
  7139  	f := sc.srv.CountError
  7140  	if f == nil {
  7141  		return err
  7142  	}
  7143  	var typ string
  7144  	var code http2ErrCode
  7145  	switch e := err.(type) {
  7146  	case http2ConnectionError:
  7147  		typ = "conn"
  7148  		code = http2ErrCode(e)
  7149  	case http2StreamError:
  7150  		typ = "stream"
  7151  		code = http2ErrCode(e.Code)
  7152  	default:
  7153  		return err
  7154  	}
  7155  	codeStr := http2errCodeName[code]
  7156  	if codeStr == "" {
  7157  		codeStr = strconv.Itoa(int(code))
  7158  	}
  7159  	f(fmt.Sprintf("%s_%s_%s", typ, codeStr, name))
  7160  	return err
  7161  }
  7162  
  7163  // A timer is a time.Timer, as an interface which can be replaced in tests.
  7164  type http2timer = interface {
  7165  	C() <-chan time.Time
  7166  	Reset(d time.Duration) bool
  7167  	Stop() bool
  7168  }
  7169  
  7170  // timeTimer adapts a time.Timer to the timer interface.
  7171  type http2timeTimer struct {
  7172  	*time.Timer
  7173  }
  7174  
  7175  func (t http2timeTimer) C() <-chan time.Time { return t.Timer.C }
  7176  
  7177  const (
  7178  	// transportDefaultConnFlow is how many connection-level flow control
  7179  	// tokens we give the server at start-up, past the default 64k.
  7180  	http2transportDefaultConnFlow = 1 << 30
  7181  
  7182  	// transportDefaultStreamFlow is how many stream-level flow
  7183  	// control tokens we announce to the peer, and how many bytes
  7184  	// we buffer per stream.
  7185  	http2transportDefaultStreamFlow = 4 << 20
  7186  
  7187  	http2defaultUserAgent = "Go-http-client/2.0"
  7188  
  7189  	// initialMaxConcurrentStreams is a connections maxConcurrentStreams until
  7190  	// it's received servers initial SETTINGS frame, which corresponds with the
  7191  	// spec's minimum recommended value.
  7192  	http2initialMaxConcurrentStreams = 100
  7193  
  7194  	// defaultMaxConcurrentStreams is a connections default maxConcurrentStreams
  7195  	// if the server doesn't include one in its initial SETTINGS frame.
  7196  	http2defaultMaxConcurrentStreams = 1000
  7197  )
  7198  
  7199  // Transport is an HTTP/2 Transport.
  7200  //
  7201  // A Transport internally caches connections to servers. It is safe
  7202  // for concurrent use by multiple goroutines.
  7203  type http2Transport struct {
  7204  	// DialTLSContext specifies an optional dial function with context for
  7205  	// creating TLS connections for requests.
  7206  	//
  7207  	// If DialTLSContext and DialTLS is nil, tls.Dial is used.
  7208  	//
  7209  	// If the returned net.Conn has a ConnectionState method like tls.Conn,
  7210  	// it will be used to set http.Response.TLS.
  7211  	DialTLSContext func(ctx context.Context, network, addr string, cfg *tls.Config) (net.Conn, error)
  7212  
  7213  	// DialTLS specifies an optional dial function for creating
  7214  	// TLS connections for requests.
  7215  	//
  7216  	// If DialTLSContext and DialTLS is nil, tls.Dial is used.
  7217  	//
  7218  	// Deprecated: Use DialTLSContext instead, which allows the transport
  7219  	// to cancel dials as soon as they are no longer needed.
  7220  	// If both are set, DialTLSContext takes priority.
  7221  	DialTLS func(network, addr string, cfg *tls.Config) (net.Conn, error)
  7222  
  7223  	// TLSClientConfig specifies the TLS configuration to use with
  7224  	// tls.Client. If nil, the default configuration is used.
  7225  	TLSClientConfig *tls.Config
  7226  
  7227  	// ConnPool optionally specifies an alternate connection pool to use.
  7228  	// If nil, the default is used.
  7229  	ConnPool http2ClientConnPool
  7230  
  7231  	// DisableCompression, if true, prevents the Transport from
  7232  	// requesting compression with an "Accept-Encoding: gzip"
  7233  	// request header when the Request contains no existing
  7234  	// Accept-Encoding value. If the Transport requests gzip on
  7235  	// its own and gets a gzipped response, it's transparently
  7236  	// decoded in the Response.Body. However, if the user
  7237  	// explicitly requested gzip it is not automatically
  7238  	// uncompressed.
  7239  	DisableCompression bool
  7240  
  7241  	// AllowHTTP, if true, permits HTTP/2 requests using the insecure,
  7242  	// plain-text "http" scheme. Note that this does not enable h2c support.
  7243  	AllowHTTP bool
  7244  
  7245  	// MaxHeaderListSize is the http2 SETTINGS_MAX_HEADER_LIST_SIZE to
  7246  	// send in the initial settings frame. It is how many bytes
  7247  	// of response headers are allowed. Unlike the http2 spec, zero here
  7248  	// means to use a default limit (currently 10MB). If you actually
  7249  	// want to advertise an unlimited value to the peer, Transport
  7250  	// interprets the highest possible value here (0xffffffff or 1<<32-1)
  7251  	// to mean no limit.
  7252  	MaxHeaderListSize uint32
  7253  
  7254  	// MaxReadFrameSize is the http2 SETTINGS_MAX_FRAME_SIZE to send in the
  7255  	// initial settings frame. It is the size in bytes of the largest frame
  7256  	// payload that the sender is willing to receive. If 0, no setting is
  7257  	// sent, and the value is provided by the peer, which should be 16384
  7258  	// according to the spec:
  7259  	// https://datatracker.ietf.org/doc/html/rfc7540#section-6.5.2.
  7260  	// Values are bounded in the range 16k to 16M.
  7261  	MaxReadFrameSize uint32
  7262  
  7263  	// MaxDecoderHeaderTableSize optionally specifies the http2
  7264  	// SETTINGS_HEADER_TABLE_SIZE to send in the initial settings frame. It
  7265  	// informs the remote endpoint of the maximum size of the header compression
  7266  	// table used to decode header blocks, in octets. If zero, the default value
  7267  	// of 4096 is used.
  7268  	MaxDecoderHeaderTableSize uint32
  7269  
  7270  	// MaxEncoderHeaderTableSize optionally specifies an upper limit for the
  7271  	// header compression table used for encoding request headers. Received
  7272  	// SETTINGS_HEADER_TABLE_SIZE settings are capped at this limit. If zero,
  7273  	// the default value of 4096 is used.
  7274  	MaxEncoderHeaderTableSize uint32
  7275  
  7276  	// StrictMaxConcurrentStreams controls whether the server's
  7277  	// SETTINGS_MAX_CONCURRENT_STREAMS should be respected
  7278  	// globally. If false, new TCP connections are created to the
  7279  	// server as needed to keep each under the per-connection
  7280  	// SETTINGS_MAX_CONCURRENT_STREAMS limit. If true, the
  7281  	// server's SETTINGS_MAX_CONCURRENT_STREAMS is interpreted as
  7282  	// a global limit and callers of RoundTrip block when needed,
  7283  	// waiting for their turn.
  7284  	StrictMaxConcurrentStreams bool
  7285  
  7286  	// IdleConnTimeout is the maximum amount of time an idle
  7287  	// (keep-alive) connection will remain idle before closing
  7288  	// itself.
  7289  	// Zero means no limit.
  7290  	IdleConnTimeout time.Duration
  7291  
  7292  	// ReadIdleTimeout is the timeout after which a health check using ping
  7293  	// frame will be carried out if no frame is received on the connection.
  7294  	// Note that a ping response will is considered a received frame, so if
  7295  	// there is no other traffic on the connection, the health check will
  7296  	// be performed every ReadIdleTimeout interval.
  7297  	// If zero, no health check is performed.
  7298  	ReadIdleTimeout time.Duration
  7299  
  7300  	// PingTimeout is the timeout after which the connection will be closed
  7301  	// if a response to Ping is not received.
  7302  	// Defaults to 15s.
  7303  	PingTimeout time.Duration
  7304  
  7305  	// WriteByteTimeout is the timeout after which the connection will be
  7306  	// closed no data can be written to it. The timeout begins when data is
  7307  	// available to write, and is extended whenever any bytes are written.
  7308  	WriteByteTimeout time.Duration
  7309  
  7310  	// CountError, if non-nil, is called on HTTP/2 transport errors.
  7311  	// It's intended to increment a metric for monitoring, such
  7312  	// as an expvar or Prometheus metric.
  7313  	// The errType consists of only ASCII word characters.
  7314  	CountError func(errType string)
  7315  
  7316  	// t1, if non-nil, is the standard library Transport using
  7317  	// this transport. Its settings are used (but not its
  7318  	// RoundTrip method, etc).
  7319  	t1 *Transport
  7320  
  7321  	connPoolOnce  sync.Once
  7322  	connPoolOrDef http2ClientConnPool // non-nil version of ConnPool
  7323  
  7324  	*http2transportTestHooks
  7325  }
  7326  
  7327  // Hook points used for testing.
  7328  // Outside of tests, t.transportTestHooks is nil and these all have minimal implementations.
  7329  // Inside tests, see the testSyncHooks function docs.
  7330  
  7331  type http2transportTestHooks struct {
  7332  	newclientconn func(*http2ClientConn)
  7333  	group         http2synctestGroupInterface
  7334  }
  7335  
  7336  func (t *http2Transport) markNewGoroutine() {
  7337  	if t != nil && t.http2transportTestHooks != nil {
  7338  		t.http2transportTestHooks.group.Join()
  7339  	}
  7340  }
  7341  
  7342  // newTimer creates a new time.Timer, or a synthetic timer in tests.
  7343  func (t *http2Transport) newTimer(d time.Duration) http2timer {
  7344  	if t.http2transportTestHooks != nil {
  7345  		return t.http2transportTestHooks.group.NewTimer(d)
  7346  	}
  7347  	return http2timeTimer{time.NewTimer(d)}
  7348  }
  7349  
  7350  // afterFunc creates a new time.AfterFunc timer, or a synthetic timer in tests.
  7351  func (t *http2Transport) afterFunc(d time.Duration, f func()) http2timer {
  7352  	if t.http2transportTestHooks != nil {
  7353  		return t.http2transportTestHooks.group.AfterFunc(d, f)
  7354  	}
  7355  	return http2timeTimer{time.AfterFunc(d, f)}
  7356  }
  7357  
  7358  func (t *http2Transport) contextWithTimeout(ctx context.Context, d time.Duration) (context.Context, context.CancelFunc) {
  7359  	if t.http2transportTestHooks != nil {
  7360  		return t.http2transportTestHooks.group.ContextWithTimeout(ctx, d)
  7361  	}
  7362  	return context.WithTimeout(ctx, d)
  7363  }
  7364  
  7365  func (t *http2Transport) maxHeaderListSize() uint32 {
  7366  	if t.MaxHeaderListSize == 0 {
  7367  		return 10 << 20
  7368  	}
  7369  	if t.MaxHeaderListSize == 0xffffffff {
  7370  		return 0
  7371  	}
  7372  	return t.MaxHeaderListSize
  7373  }
  7374  
  7375  func (t *http2Transport) maxFrameReadSize() uint32 {
  7376  	if t.MaxReadFrameSize == 0 {
  7377  		return 0 // use the default provided by the peer
  7378  	}
  7379  	if t.MaxReadFrameSize < http2minMaxFrameSize {
  7380  		return http2minMaxFrameSize
  7381  	}
  7382  	if t.MaxReadFrameSize > http2maxFrameSize {
  7383  		return http2maxFrameSize
  7384  	}
  7385  	return t.MaxReadFrameSize
  7386  }
  7387  
  7388  func (t *http2Transport) disableCompression() bool {
  7389  	return t.DisableCompression || (t.t1 != nil && t.t1.DisableCompression)
  7390  }
  7391  
  7392  func (t *http2Transport) pingTimeout() time.Duration {
  7393  	if t.PingTimeout == 0 {
  7394  		return 15 * time.Second
  7395  	}
  7396  	return t.PingTimeout
  7397  
  7398  }
  7399  
  7400  // ConfigureTransport configures a net/http HTTP/1 Transport to use HTTP/2.
  7401  // It returns an error if t1 has already been HTTP/2-enabled.
  7402  //
  7403  // Use ConfigureTransports instead to configure the HTTP/2 Transport.
  7404  func http2ConfigureTransport(t1 *Transport) error {
  7405  	_, err := http2ConfigureTransports(t1)
  7406  	return err
  7407  }
  7408  
  7409  // ConfigureTransports configures a net/http HTTP/1 Transport to use HTTP/2.
  7410  // It returns a new HTTP/2 Transport for further configuration.
  7411  // It returns an error if t1 has already been HTTP/2-enabled.
  7412  func http2ConfigureTransports(t1 *Transport) (*http2Transport, error) {
  7413  	return http2configureTransports(t1)
  7414  }
  7415  
  7416  func http2configureTransports(t1 *Transport) (*http2Transport, error) {
  7417  	connPool := new(http2clientConnPool)
  7418  	t2 := &http2Transport{
  7419  		ConnPool: http2noDialClientConnPool{connPool},
  7420  		t1:       t1,
  7421  	}
  7422  	connPool.t = t2
  7423  	if err := http2registerHTTPSProtocol(t1, http2noDialH2RoundTripper{t2}); err != nil {
  7424  		return nil, err
  7425  	}
  7426  	if t1.TLSClientConfig == nil {
  7427  		t1.TLSClientConfig = new(tls.Config)
  7428  	}
  7429  	if !http2strSliceContains(t1.TLSClientConfig.NextProtos, "h2") {
  7430  		t1.TLSClientConfig.NextProtos = append([]string{"h2"}, t1.TLSClientConfig.NextProtos...)
  7431  	}
  7432  	if !http2strSliceContains(t1.TLSClientConfig.NextProtos, "http/1.1") {
  7433  		t1.TLSClientConfig.NextProtos = append(t1.TLSClientConfig.NextProtos, "http/1.1")
  7434  	}
  7435  	upgradeFn := func(authority string, c *tls.Conn) RoundTripper {
  7436  		addr := http2authorityAddr("https", authority)
  7437  		if used, err := connPool.addConnIfNeeded(addr, t2, c); err != nil {
  7438  			go c.Close()
  7439  			return http2erringRoundTripper{err}
  7440  		} else if !used {
  7441  			// Turns out we don't need this c.
  7442  			// For example, two goroutines made requests to the same host
  7443  			// at the same time, both kicking off TCP dials. (since protocol
  7444  			// was unknown)
  7445  			go c.Close()
  7446  		}
  7447  		return t2
  7448  	}
  7449  	if m := t1.TLSNextProto; len(m) == 0 {
  7450  		t1.TLSNextProto = map[string]func(string, *tls.Conn) RoundTripper{
  7451  			"h2": upgradeFn,
  7452  		}
  7453  	} else {
  7454  		m["h2"] = upgradeFn
  7455  	}
  7456  	return t2, nil
  7457  }
  7458  
  7459  func (t *http2Transport) connPool() http2ClientConnPool {
  7460  	t.connPoolOnce.Do(t.initConnPool)
  7461  	return t.connPoolOrDef
  7462  }
  7463  
  7464  func (t *http2Transport) initConnPool() {
  7465  	if t.ConnPool != nil {
  7466  		t.connPoolOrDef = t.ConnPool
  7467  	} else {
  7468  		t.connPoolOrDef = &http2clientConnPool{t: t}
  7469  	}
  7470  }
  7471  
  7472  // ClientConn is the state of a single HTTP/2 client connection to an
  7473  // HTTP/2 server.
  7474  type http2ClientConn struct {
  7475  	t             *http2Transport
  7476  	tconn         net.Conn             // usually *tls.Conn, except specialized impls
  7477  	tlsState      *tls.ConnectionState // nil only for specialized impls
  7478  	reused        uint32               // whether conn is being reused; atomic
  7479  	singleUse     bool                 // whether being used for a single http.Request
  7480  	getConnCalled bool                 // used by clientConnPool
  7481  
  7482  	// readLoop goroutine fields:
  7483  	readerDone chan struct{} // closed on error
  7484  	readerErr  error         // set before readerDone is closed
  7485  
  7486  	idleTimeout time.Duration // or 0 for never
  7487  	idleTimer   http2timer
  7488  
  7489  	mu              sync.Mutex   // guards following
  7490  	cond            *sync.Cond   // hold mu; broadcast on flow/closed changes
  7491  	flow            http2outflow // our conn-level flow control quota (cs.outflow is per stream)
  7492  	inflow          http2inflow  // peer's conn-level flow control
  7493  	doNotReuse      bool         // whether conn is marked to not be reused for any future requests
  7494  	closing         bool
  7495  	closed          bool
  7496  	seenSettings    bool                          // true if we've seen a settings frame, false otherwise
  7497  	wantSettingsAck bool                          // we sent a SETTINGS frame and haven't heard back
  7498  	goAway          *http2GoAwayFrame             // if non-nil, the GoAwayFrame we received
  7499  	goAwayDebug     string                        // goAway frame's debug data, retained as a string
  7500  	streams         map[uint32]*http2clientStream // client-initiated
  7501  	streamsReserved int                           // incr by ReserveNewRequest; decr on RoundTrip
  7502  	nextStreamID    uint32
  7503  	pendingRequests int                       // requests blocked and waiting to be sent because len(streams) == maxConcurrentStreams
  7504  	pings           map[[8]byte]chan struct{} // in flight ping data to notification channel
  7505  	br              *bufio.Reader
  7506  	lastActive      time.Time
  7507  	lastIdle        time.Time // time last idle
  7508  	// Settings from peer: (also guarded by wmu)
  7509  	maxFrameSize           uint32
  7510  	maxConcurrentStreams   uint32
  7511  	peerMaxHeaderListSize  uint64
  7512  	peerMaxHeaderTableSize uint32
  7513  	initialWindowSize      uint32
  7514  
  7515  	// reqHeaderMu is a 1-element semaphore channel controlling access to sending new requests.
  7516  	// Write to reqHeaderMu to lock it, read from it to unlock.
  7517  	// Lock reqmu BEFORE mu or wmu.
  7518  	reqHeaderMu chan struct{}
  7519  
  7520  	// wmu is held while writing.
  7521  	// Acquire BEFORE mu when holding both, to avoid blocking mu on network writes.
  7522  	// Only acquire both at the same time when changing peer settings.
  7523  	wmu  sync.Mutex
  7524  	bw   *bufio.Writer
  7525  	fr   *http2Framer
  7526  	werr error        // first write error that has occurred
  7527  	hbuf bytes.Buffer // HPACK encoder writes into this
  7528  	henc *hpack.Encoder
  7529  }
  7530  
  7531  // clientStream is the state for a single HTTP/2 stream. One of these
  7532  // is created for each Transport.RoundTrip call.
  7533  type http2clientStream struct {
  7534  	cc *http2ClientConn
  7535  
  7536  	// Fields of Request that we may access even after the response body is closed.
  7537  	ctx       context.Context
  7538  	reqCancel <-chan struct{}
  7539  
  7540  	trace         *httptrace.ClientTrace // or nil
  7541  	ID            uint32
  7542  	bufPipe       http2pipe // buffered pipe with the flow-controlled response payload
  7543  	requestedGzip bool
  7544  	isHead        bool
  7545  
  7546  	abortOnce sync.Once
  7547  	abort     chan struct{} // closed to signal stream should end immediately
  7548  	abortErr  error         // set if abort is closed
  7549  
  7550  	peerClosed chan struct{} // closed when the peer sends an END_STREAM flag
  7551  	donec      chan struct{} // closed after the stream is in the closed state
  7552  	on100      chan struct{} // buffered; written to if a 100 is received
  7553  
  7554  	respHeaderRecv chan struct{} // closed when headers are received
  7555  	res            *Response     // set if respHeaderRecv is closed
  7556  
  7557  	flow        http2outflow // guarded by cc.mu
  7558  	inflow      http2inflow  // guarded by cc.mu
  7559  	bytesRemain int64        // -1 means unknown; owned by transportResponseBody.Read
  7560  	readErr     error        // sticky read error; owned by transportResponseBody.Read
  7561  
  7562  	reqBody              io.ReadCloser
  7563  	reqBodyContentLength int64         // -1 means unknown
  7564  	reqBodyClosed        chan struct{} // guarded by cc.mu; non-nil on Close, closed when done
  7565  
  7566  	// owned by writeRequest:
  7567  	sentEndStream bool // sent an END_STREAM flag to the peer
  7568  	sentHeaders   bool
  7569  
  7570  	// owned by clientConnReadLoop:
  7571  	firstByte    bool  // got the first response byte
  7572  	pastHeaders  bool  // got first MetaHeadersFrame (actual headers)
  7573  	pastTrailers bool  // got optional second MetaHeadersFrame (trailers)
  7574  	num1xx       uint8 // number of 1xx responses seen
  7575  	readClosed   bool  // peer sent an END_STREAM flag
  7576  	readAborted  bool  // read loop reset the stream
  7577  
  7578  	trailer    Header  // accumulated trailers
  7579  	resTrailer *Header // client's Response.Trailer
  7580  }
  7581  
  7582  var http2got1xxFuncForTests func(int, textproto.MIMEHeader) error
  7583  
  7584  // get1xxTraceFunc returns the value of request's httptrace.ClientTrace.Got1xxResponse func,
  7585  // if any. It returns nil if not set or if the Go version is too old.
  7586  func (cs *http2clientStream) get1xxTraceFunc() func(int, textproto.MIMEHeader) error {
  7587  	if fn := http2got1xxFuncForTests; fn != nil {
  7588  		return fn
  7589  	}
  7590  	return http2traceGot1xxResponseFunc(cs.trace)
  7591  }
  7592  
  7593  func (cs *http2clientStream) abortStream(err error) {
  7594  	cs.cc.mu.Lock()
  7595  	defer cs.cc.mu.Unlock()
  7596  	cs.abortStreamLocked(err)
  7597  }
  7598  
  7599  func (cs *http2clientStream) abortStreamLocked(err error) {
  7600  	cs.abortOnce.Do(func() {
  7601  		cs.abortErr = err
  7602  		close(cs.abort)
  7603  	})
  7604  	if cs.reqBody != nil {
  7605  		cs.closeReqBodyLocked()
  7606  	}
  7607  	// TODO(dneil): Clean up tests where cs.cc.cond is nil.
  7608  	if cs.cc.cond != nil {
  7609  		// Wake up writeRequestBody if it is waiting on flow control.
  7610  		cs.cc.cond.Broadcast()
  7611  	}
  7612  }
  7613  
  7614  func (cs *http2clientStream) abortRequestBodyWrite() {
  7615  	cc := cs.cc
  7616  	cc.mu.Lock()
  7617  	defer cc.mu.Unlock()
  7618  	if cs.reqBody != nil && cs.reqBodyClosed == nil {
  7619  		cs.closeReqBodyLocked()
  7620  		cc.cond.Broadcast()
  7621  	}
  7622  }
  7623  
  7624  func (cs *http2clientStream) closeReqBodyLocked() {
  7625  	if cs.reqBodyClosed != nil {
  7626  		return
  7627  	}
  7628  	cs.reqBodyClosed = make(chan struct{})
  7629  	reqBodyClosed := cs.reqBodyClosed
  7630  	go func() {
  7631  		cs.cc.t.markNewGoroutine()
  7632  		cs.reqBody.Close()
  7633  		close(reqBodyClosed)
  7634  	}()
  7635  }
  7636  
  7637  type http2stickyErrWriter struct {
  7638  	conn    net.Conn
  7639  	timeout time.Duration
  7640  	err     *error
  7641  }
  7642  
  7643  func (sew http2stickyErrWriter) Write(p []byte) (n int, err error) {
  7644  	if *sew.err != nil {
  7645  		return 0, *sew.err
  7646  	}
  7647  	for {
  7648  		if sew.timeout != 0 {
  7649  			sew.conn.SetWriteDeadline(time.Now().Add(sew.timeout))
  7650  		}
  7651  		nn, err := sew.conn.Write(p[n:])
  7652  		n += nn
  7653  		if n < len(p) && nn > 0 && errors.Is(err, os.ErrDeadlineExceeded) {
  7654  			// Keep extending the deadline so long as we're making progress.
  7655  			continue
  7656  		}
  7657  		if sew.timeout != 0 {
  7658  			sew.conn.SetWriteDeadline(time.Time{})
  7659  		}
  7660  		*sew.err = err
  7661  		return n, err
  7662  	}
  7663  }
  7664  
  7665  // noCachedConnError is the concrete type of ErrNoCachedConn, which
  7666  // needs to be detected by net/http regardless of whether it's its
  7667  // bundled version (in h2_bundle.go with a rewritten type name) or
  7668  // from a user's x/net/http2. As such, as it has a unique method name
  7669  // (IsHTTP2NoCachedConnError) that net/http sniffs for via func
  7670  // isNoCachedConnError.
  7671  type http2noCachedConnError struct{}
  7672  
  7673  func (http2noCachedConnError) IsHTTP2NoCachedConnError() {}
  7674  
  7675  func (http2noCachedConnError) Error() string { return "http2: no cached connection was available" }
  7676  
  7677  // isNoCachedConnError reports whether err is of type noCachedConnError
  7678  // or its equivalent renamed type in net/http2's h2_bundle.go. Both types
  7679  // may coexist in the same running program.
  7680  func http2isNoCachedConnError(err error) bool {
  7681  	_, ok := err.(interface{ IsHTTP2NoCachedConnError() })
  7682  	return ok
  7683  }
  7684  
  7685  var http2ErrNoCachedConn error = http2noCachedConnError{}
  7686  
  7687  // RoundTripOpt are options for the Transport.RoundTripOpt method.
  7688  type http2RoundTripOpt struct {
  7689  	// OnlyCachedConn controls whether RoundTripOpt may
  7690  	// create a new TCP connection. If set true and
  7691  	// no cached connection is available, RoundTripOpt
  7692  	// will return ErrNoCachedConn.
  7693  	OnlyCachedConn bool
  7694  }
  7695  
  7696  func (t *http2Transport) RoundTrip(req *Request) (*Response, error) {
  7697  	return t.RoundTripOpt(req, http2RoundTripOpt{})
  7698  }
  7699  
  7700  // authorityAddr returns a given authority (a host/IP, or host:port / ip:port)
  7701  // and returns a host:port. The port 443 is added if needed.
  7702  func http2authorityAddr(scheme string, authority string) (addr string) {
  7703  	host, port, err := net.SplitHostPort(authority)
  7704  	if err != nil { // authority didn't have a port
  7705  		host = authority
  7706  		port = ""
  7707  	}
  7708  	if port == "" { // authority's port was empty
  7709  		port = "443"
  7710  		if scheme == "http" {
  7711  			port = "80"
  7712  		}
  7713  	}
  7714  	if a, err := idna.ToASCII(host); err == nil {
  7715  		host = a
  7716  	}
  7717  	// IPv6 address literal, without a port:
  7718  	if strings.HasPrefix(host, "[") && strings.HasSuffix(host, "]") {
  7719  		return host + ":" + port
  7720  	}
  7721  	return net.JoinHostPort(host, port)
  7722  }
  7723  
  7724  // RoundTripOpt is like RoundTrip, but takes options.
  7725  func (t *http2Transport) RoundTripOpt(req *Request, opt http2RoundTripOpt) (*Response, error) {
  7726  	if !(req.URL.Scheme == "https" || (req.URL.Scheme == "http" && t.AllowHTTP)) {
  7727  		return nil, errors.New("http2: unsupported scheme")
  7728  	}
  7729  
  7730  	addr := http2authorityAddr(req.URL.Scheme, req.URL.Host)
  7731  	for retry := 0; ; retry++ {
  7732  		cc, err := t.connPool().GetClientConn(req, addr)
  7733  		if err != nil {
  7734  			t.vlogf("http2: Transport failed to get client conn for %s: %v", addr, err)
  7735  			return nil, err
  7736  		}
  7737  		reused := !atomic.CompareAndSwapUint32(&cc.reused, 0, 1)
  7738  		http2traceGotConn(req, cc, reused)
  7739  		res, err := cc.RoundTrip(req)
  7740  		if err != nil && retry <= 6 {
  7741  			roundTripErr := err
  7742  			if req, err = http2shouldRetryRequest(req, err); err == nil {
  7743  				// After the first retry, do exponential backoff with 10% jitter.
  7744  				if retry == 0 {
  7745  					t.vlogf("RoundTrip retrying after failure: %v", roundTripErr)
  7746  					continue
  7747  				}
  7748  				backoff := float64(uint(1) << (uint(retry) - 1))
  7749  				backoff += backoff * (0.1 * mathrand.Float64())
  7750  				d := time.Second * time.Duration(backoff)
  7751  				tm := t.newTimer(d)
  7752  				select {
  7753  				case <-tm.C():
  7754  					t.vlogf("RoundTrip retrying after failure: %v", roundTripErr)
  7755  					continue
  7756  				case <-req.Context().Done():
  7757  					tm.Stop()
  7758  					err = req.Context().Err()
  7759  				}
  7760  			}
  7761  		}
  7762  		if err != nil {
  7763  			t.vlogf("RoundTrip failure: %v", err)
  7764  			return nil, err
  7765  		}
  7766  		return res, nil
  7767  	}
  7768  }
  7769  
  7770  // CloseIdleConnections closes any connections which were previously
  7771  // connected from previous requests but are now sitting idle.
  7772  // It does not interrupt any connections currently in use.
  7773  func (t *http2Transport) CloseIdleConnections() {
  7774  	if cp, ok := t.connPool().(http2clientConnPoolIdleCloser); ok {
  7775  		cp.closeIdleConnections()
  7776  	}
  7777  }
  7778  
  7779  var (
  7780  	http2errClientConnClosed    = errors.New("http2: client conn is closed")
  7781  	http2errClientConnUnusable  = errors.New("http2: client conn not usable")
  7782  	http2errClientConnGotGoAway = errors.New("http2: Transport received Server's graceful shutdown GOAWAY")
  7783  )
  7784  
  7785  // shouldRetryRequest is called by RoundTrip when a request fails to get
  7786  // response headers. It is always called with a non-nil error.
  7787  // It returns either a request to retry (either the same request, or a
  7788  // modified clone), or an error if the request can't be replayed.
  7789  func http2shouldRetryRequest(req *Request, err error) (*Request, error) {
  7790  	if !http2canRetryError(err) {
  7791  		return nil, err
  7792  	}
  7793  	// If the Body is nil (or http.NoBody), it's safe to reuse
  7794  	// this request and its Body.
  7795  	if req.Body == nil || req.Body == NoBody {
  7796  		return req, nil
  7797  	}
  7798  
  7799  	// If the request body can be reset back to its original
  7800  	// state via the optional req.GetBody, do that.
  7801  	if req.GetBody != nil {
  7802  		body, err := req.GetBody()
  7803  		if err != nil {
  7804  			return nil, err
  7805  		}
  7806  		newReq := *req
  7807  		newReq.Body = body
  7808  		return &newReq, nil
  7809  	}
  7810  
  7811  	// The Request.Body can't reset back to the beginning, but we
  7812  	// don't seem to have started to read from it yet, so reuse
  7813  	// the request directly.
  7814  	if err == http2errClientConnUnusable {
  7815  		return req, nil
  7816  	}
  7817  
  7818  	return nil, fmt.Errorf("http2: Transport: cannot retry err [%v] after Request.Body was written; define Request.GetBody to avoid this error", err)
  7819  }
  7820  
  7821  func http2canRetryError(err error) bool {
  7822  	if err == http2errClientConnUnusable || err == http2errClientConnGotGoAway {
  7823  		return true
  7824  	}
  7825  	if se, ok := err.(http2StreamError); ok {
  7826  		if se.Code == http2ErrCodeProtocol && se.Cause == http2errFromPeer {
  7827  			// See golang/go#47635, golang/go#42777
  7828  			return true
  7829  		}
  7830  		return se.Code == http2ErrCodeRefusedStream
  7831  	}
  7832  	return false
  7833  }
  7834  
  7835  func (t *http2Transport) dialClientConn(ctx context.Context, addr string, singleUse bool) (*http2ClientConn, error) {
  7836  	if t.http2transportTestHooks != nil {
  7837  		return t.newClientConn(nil, singleUse)
  7838  	}
  7839  	host, _, err := net.SplitHostPort(addr)
  7840  	if err != nil {
  7841  		return nil, err
  7842  	}
  7843  	tconn, err := t.dialTLS(ctx, "tcp", addr, t.newTLSConfig(host))
  7844  	if err != nil {
  7845  		return nil, err
  7846  	}
  7847  	return t.newClientConn(tconn, singleUse)
  7848  }
  7849  
  7850  func (t *http2Transport) newTLSConfig(host string) *tls.Config {
  7851  	cfg := new(tls.Config)
  7852  	if t.TLSClientConfig != nil {
  7853  		*cfg = *t.TLSClientConfig.Clone()
  7854  	}
  7855  	if !http2strSliceContains(cfg.NextProtos, http2NextProtoTLS) {
  7856  		cfg.NextProtos = append([]string{http2NextProtoTLS}, cfg.NextProtos...)
  7857  	}
  7858  	if cfg.ServerName == "" {
  7859  		cfg.ServerName = host
  7860  	}
  7861  	return cfg
  7862  }
  7863  
  7864  func (t *http2Transport) dialTLS(ctx context.Context, network, addr string, tlsCfg *tls.Config) (net.Conn, error) {
  7865  	if t.DialTLSContext != nil {
  7866  		return t.DialTLSContext(ctx, network, addr, tlsCfg)
  7867  	} else if t.DialTLS != nil {
  7868  		return t.DialTLS(network, addr, tlsCfg)
  7869  	}
  7870  
  7871  	tlsCn, err := t.dialTLSWithContext(ctx, network, addr, tlsCfg)
  7872  	if err != nil {
  7873  		return nil, err
  7874  	}
  7875  	state := tlsCn.ConnectionState()
  7876  	if p := state.NegotiatedProtocol; p != http2NextProtoTLS {
  7877  		return nil, fmt.Errorf("http2: unexpected ALPN protocol %q; want %q", p, http2NextProtoTLS)
  7878  	}
  7879  	if !state.NegotiatedProtocolIsMutual {
  7880  		return nil, errors.New("http2: could not negotiate protocol mutually")
  7881  	}
  7882  	return tlsCn, nil
  7883  }
  7884  
  7885  // disableKeepAlives reports whether connections should be closed as
  7886  // soon as possible after handling the first request.
  7887  func (t *http2Transport) disableKeepAlives() bool {
  7888  	return t.t1 != nil && t.t1.DisableKeepAlives
  7889  }
  7890  
  7891  func (t *http2Transport) expectContinueTimeout() time.Duration {
  7892  	if t.t1 == nil {
  7893  		return 0
  7894  	}
  7895  	return t.t1.ExpectContinueTimeout
  7896  }
  7897  
  7898  func (t *http2Transport) maxDecoderHeaderTableSize() uint32 {
  7899  	if v := t.MaxDecoderHeaderTableSize; v > 0 {
  7900  		return v
  7901  	}
  7902  	return http2initialHeaderTableSize
  7903  }
  7904  
  7905  func (t *http2Transport) maxEncoderHeaderTableSize() uint32 {
  7906  	if v := t.MaxEncoderHeaderTableSize; v > 0 {
  7907  		return v
  7908  	}
  7909  	return http2initialHeaderTableSize
  7910  }
  7911  
  7912  func (t *http2Transport) NewClientConn(c net.Conn) (*http2ClientConn, error) {
  7913  	return t.newClientConn(c, t.disableKeepAlives())
  7914  }
  7915  
  7916  func (t *http2Transport) newClientConn(c net.Conn, singleUse bool) (*http2ClientConn, error) {
  7917  	cc := &http2ClientConn{
  7918  		t:                     t,
  7919  		tconn:                 c,
  7920  		readerDone:            make(chan struct{}),
  7921  		nextStreamID:          1,
  7922  		maxFrameSize:          16 << 10,                         // spec default
  7923  		initialWindowSize:     65535,                            // spec default
  7924  		maxConcurrentStreams:  http2initialMaxConcurrentStreams, // "infinite", per spec. Use a smaller value until we have received server settings.
  7925  		peerMaxHeaderListSize: 0xffffffffffffffff,               // "infinite", per spec. Use 2^64-1 instead.
  7926  		streams:               make(map[uint32]*http2clientStream),
  7927  		singleUse:             singleUse,
  7928  		wantSettingsAck:       true,
  7929  		pings:                 make(map[[8]byte]chan struct{}),
  7930  		reqHeaderMu:           make(chan struct{}, 1),
  7931  	}
  7932  	if t.http2transportTestHooks != nil {
  7933  		t.markNewGoroutine()
  7934  		t.http2transportTestHooks.newclientconn(cc)
  7935  		c = cc.tconn
  7936  	}
  7937  	if http2VerboseLogs {
  7938  		t.vlogf("http2: Transport creating client conn %p to %v", cc, c.RemoteAddr())
  7939  	}
  7940  
  7941  	cc.cond = sync.NewCond(&cc.mu)
  7942  	cc.flow.add(int32(http2initialWindowSize))
  7943  
  7944  	// TODO: adjust this writer size to account for frame size +
  7945  	// MTU + crypto/tls record padding.
  7946  	cc.bw = bufio.NewWriter(http2stickyErrWriter{
  7947  		conn:    c,
  7948  		timeout: t.WriteByteTimeout,
  7949  		err:     &cc.werr,
  7950  	})
  7951  	cc.br = bufio.NewReader(c)
  7952  	cc.fr = http2NewFramer(cc.bw, cc.br)
  7953  	if t.maxFrameReadSize() != 0 {
  7954  		cc.fr.SetMaxReadFrameSize(t.maxFrameReadSize())
  7955  	}
  7956  	if t.CountError != nil {
  7957  		cc.fr.countError = t.CountError
  7958  	}
  7959  	maxHeaderTableSize := t.maxDecoderHeaderTableSize()
  7960  	cc.fr.ReadMetaHeaders = hpack.NewDecoder(maxHeaderTableSize, nil)
  7961  	cc.fr.MaxHeaderListSize = t.maxHeaderListSize()
  7962  
  7963  	cc.henc = hpack.NewEncoder(&cc.hbuf)
  7964  	cc.henc.SetMaxDynamicTableSizeLimit(t.maxEncoderHeaderTableSize())
  7965  	cc.peerMaxHeaderTableSize = http2initialHeaderTableSize
  7966  
  7967  	if t.AllowHTTP {
  7968  		cc.nextStreamID = 3
  7969  	}
  7970  
  7971  	if cs, ok := c.(http2connectionStater); ok {
  7972  		state := cs.ConnectionState()
  7973  		cc.tlsState = &state
  7974  	}
  7975  
  7976  	initialSettings := []http2Setting{
  7977  		{ID: http2SettingEnablePush, Val: 0},
  7978  		{ID: http2SettingInitialWindowSize, Val: http2transportDefaultStreamFlow},
  7979  	}
  7980  	if max := t.maxFrameReadSize(); max != 0 {
  7981  		initialSettings = append(initialSettings, http2Setting{ID: http2SettingMaxFrameSize, Val: max})
  7982  	}
  7983  	if max := t.maxHeaderListSize(); max != 0 {
  7984  		initialSettings = append(initialSettings, http2Setting{ID: http2SettingMaxHeaderListSize, Val: max})
  7985  	}
  7986  	if maxHeaderTableSize != http2initialHeaderTableSize {
  7987  		initialSettings = append(initialSettings, http2Setting{ID: http2SettingHeaderTableSize, Val: maxHeaderTableSize})
  7988  	}
  7989  
  7990  	cc.bw.Write(http2clientPreface)
  7991  	cc.fr.WriteSettings(initialSettings...)
  7992  	cc.fr.WriteWindowUpdate(0, http2transportDefaultConnFlow)
  7993  	cc.inflow.init(http2transportDefaultConnFlow + http2initialWindowSize)
  7994  	cc.bw.Flush()
  7995  	if cc.werr != nil {
  7996  		cc.Close()
  7997  		return nil, cc.werr
  7998  	}
  7999  
  8000  	// Start the idle timer after the connection is fully initialized.
  8001  	if d := t.idleConnTimeout(); d != 0 {
  8002  		cc.idleTimeout = d
  8003  		cc.idleTimer = t.afterFunc(d, cc.onIdleTimeout)
  8004  	}
  8005  
  8006  	go cc.readLoop()
  8007  	return cc, nil
  8008  }
  8009  
  8010  func (cc *http2ClientConn) healthCheck() {
  8011  	pingTimeout := cc.t.pingTimeout()
  8012  	// We don't need to periodically ping in the health check, because the readLoop of ClientConn will
  8013  	// trigger the healthCheck again if there is no frame received.
  8014  	ctx, cancel := cc.t.contextWithTimeout(context.Background(), pingTimeout)
  8015  	defer cancel()
  8016  	cc.vlogf("http2: Transport sending health check")
  8017  	err := cc.Ping(ctx)
  8018  	if err != nil {
  8019  		cc.vlogf("http2: Transport health check failure: %v", err)
  8020  		cc.closeForLostPing()
  8021  	} else {
  8022  		cc.vlogf("http2: Transport health check success")
  8023  	}
  8024  }
  8025  
  8026  // SetDoNotReuse marks cc as not reusable for future HTTP requests.
  8027  func (cc *http2ClientConn) SetDoNotReuse() {
  8028  	cc.mu.Lock()
  8029  	defer cc.mu.Unlock()
  8030  	cc.doNotReuse = true
  8031  }
  8032  
  8033  func (cc *http2ClientConn) setGoAway(f *http2GoAwayFrame) {
  8034  	cc.mu.Lock()
  8035  	defer cc.mu.Unlock()
  8036  
  8037  	old := cc.goAway
  8038  	cc.goAway = f
  8039  
  8040  	// Merge the previous and current GoAway error frames.
  8041  	if cc.goAwayDebug == "" {
  8042  		cc.goAwayDebug = string(f.DebugData())
  8043  	}
  8044  	if old != nil && old.ErrCode != http2ErrCodeNo {
  8045  		cc.goAway.ErrCode = old.ErrCode
  8046  	}
  8047  	last := f.LastStreamID
  8048  	for streamID, cs := range cc.streams {
  8049  		if streamID <= last {
  8050  			// The server's GOAWAY indicates that it received this stream.
  8051  			// It will either finish processing it, or close the connection
  8052  			// without doing so. Either way, leave the stream alone for now.
  8053  			continue
  8054  		}
  8055  		if streamID == 1 && cc.goAway.ErrCode != http2ErrCodeNo {
  8056  			// Don't retry the first stream on a connection if we get a non-NO error.
  8057  			// If the server is sending an error on a new connection,
  8058  			// retrying the request on a new one probably isn't going to work.
  8059  			cs.abortStreamLocked(fmt.Errorf("http2: Transport received GOAWAY from server ErrCode:%v", cc.goAway.ErrCode))
  8060  		} else {
  8061  			// Aborting the stream with errClentConnGotGoAway indicates that
  8062  			// the request should be retried on a new connection.
  8063  			cs.abortStreamLocked(http2errClientConnGotGoAway)
  8064  		}
  8065  	}
  8066  }
  8067  
  8068  // CanTakeNewRequest reports whether the connection can take a new request,
  8069  // meaning it has not been closed or received or sent a GOAWAY.
  8070  //
  8071  // If the caller is going to immediately make a new request on this
  8072  // connection, use ReserveNewRequest instead.
  8073  func (cc *http2ClientConn) CanTakeNewRequest() bool {
  8074  	cc.mu.Lock()
  8075  	defer cc.mu.Unlock()
  8076  	return cc.canTakeNewRequestLocked()
  8077  }
  8078  
  8079  // ReserveNewRequest is like CanTakeNewRequest but also reserves a
  8080  // concurrent stream in cc. The reservation is decremented on the
  8081  // next call to RoundTrip.
  8082  func (cc *http2ClientConn) ReserveNewRequest() bool {
  8083  	cc.mu.Lock()
  8084  	defer cc.mu.Unlock()
  8085  	if st := cc.idleStateLocked(); !st.canTakeNewRequest {
  8086  		return false
  8087  	}
  8088  	cc.streamsReserved++
  8089  	return true
  8090  }
  8091  
  8092  // ClientConnState describes the state of a ClientConn.
  8093  type http2ClientConnState struct {
  8094  	// Closed is whether the connection is closed.
  8095  	Closed bool
  8096  
  8097  	// Closing is whether the connection is in the process of
  8098  	// closing. It may be closing due to shutdown, being a
  8099  	// single-use connection, being marked as DoNotReuse, or
  8100  	// having received a GOAWAY frame.
  8101  	Closing bool
  8102  
  8103  	// StreamsActive is how many streams are active.
  8104  	StreamsActive int
  8105  
  8106  	// StreamsReserved is how many streams have been reserved via
  8107  	// ClientConn.ReserveNewRequest.
  8108  	StreamsReserved int
  8109  
  8110  	// StreamsPending is how many requests have been sent in excess
  8111  	// of the peer's advertised MaxConcurrentStreams setting and
  8112  	// are waiting for other streams to complete.
  8113  	StreamsPending int
  8114  
  8115  	// MaxConcurrentStreams is how many concurrent streams the
  8116  	// peer advertised as acceptable. Zero means no SETTINGS
  8117  	// frame has been received yet.
  8118  	MaxConcurrentStreams uint32
  8119  
  8120  	// LastIdle, if non-zero, is when the connection last
  8121  	// transitioned to idle state.
  8122  	LastIdle time.Time
  8123  }
  8124  
  8125  // State returns a snapshot of cc's state.
  8126  func (cc *http2ClientConn) State() http2ClientConnState {
  8127  	cc.wmu.Lock()
  8128  	maxConcurrent := cc.maxConcurrentStreams
  8129  	if !cc.seenSettings {
  8130  		maxConcurrent = 0
  8131  	}
  8132  	cc.wmu.Unlock()
  8133  
  8134  	cc.mu.Lock()
  8135  	defer cc.mu.Unlock()
  8136  	return http2ClientConnState{
  8137  		Closed:               cc.closed,
  8138  		Closing:              cc.closing || cc.singleUse || cc.doNotReuse || cc.goAway != nil,
  8139  		StreamsActive:        len(cc.streams),
  8140  		StreamsReserved:      cc.streamsReserved,
  8141  		StreamsPending:       cc.pendingRequests,
  8142  		LastIdle:             cc.lastIdle,
  8143  		MaxConcurrentStreams: maxConcurrent,
  8144  	}
  8145  }
  8146  
  8147  // clientConnIdleState describes the suitability of a client
  8148  // connection to initiate a new RoundTrip request.
  8149  type http2clientConnIdleState struct {
  8150  	canTakeNewRequest bool
  8151  }
  8152  
  8153  func (cc *http2ClientConn) idleState() http2clientConnIdleState {
  8154  	cc.mu.Lock()
  8155  	defer cc.mu.Unlock()
  8156  	return cc.idleStateLocked()
  8157  }
  8158  
  8159  func (cc *http2ClientConn) idleStateLocked() (st http2clientConnIdleState) {
  8160  	if cc.singleUse && cc.nextStreamID > 1 {
  8161  		return
  8162  	}
  8163  	var maxConcurrentOkay bool
  8164  	if cc.t.StrictMaxConcurrentStreams {
  8165  		// We'll tell the caller we can take a new request to
  8166  		// prevent the caller from dialing a new TCP
  8167  		// connection, but then we'll block later before
  8168  		// writing it.
  8169  		maxConcurrentOkay = true
  8170  	} else {
  8171  		maxConcurrentOkay = int64(len(cc.streams)+cc.streamsReserved+1) <= int64(cc.maxConcurrentStreams)
  8172  	}
  8173  
  8174  	st.canTakeNewRequest = cc.goAway == nil && !cc.closed && !cc.closing && maxConcurrentOkay &&
  8175  		!cc.doNotReuse &&
  8176  		int64(cc.nextStreamID)+2*int64(cc.pendingRequests) < math.MaxInt32 &&
  8177  		!cc.tooIdleLocked()
  8178  	return
  8179  }
  8180  
  8181  func (cc *http2ClientConn) canTakeNewRequestLocked() bool {
  8182  	st := cc.idleStateLocked()
  8183  	return st.canTakeNewRequest
  8184  }
  8185  
  8186  // tooIdleLocked reports whether this connection has been been sitting idle
  8187  // for too much wall time.
  8188  func (cc *http2ClientConn) tooIdleLocked() bool {
  8189  	// The Round(0) strips the monontonic clock reading so the
  8190  	// times are compared based on their wall time. We don't want
  8191  	// to reuse a connection that's been sitting idle during
  8192  	// VM/laptop suspend if monotonic time was also frozen.
  8193  	return cc.idleTimeout != 0 && !cc.lastIdle.IsZero() && time.Since(cc.lastIdle.Round(0)) > cc.idleTimeout
  8194  }
  8195  
  8196  // onIdleTimeout is called from a time.AfterFunc goroutine. It will
  8197  // only be called when we're idle, but because we're coming from a new
  8198  // goroutine, there could be a new request coming in at the same time,
  8199  // so this simply calls the synchronized closeIfIdle to shut down this
  8200  // connection. The timer could just call closeIfIdle, but this is more
  8201  // clear.
  8202  func (cc *http2ClientConn) onIdleTimeout() {
  8203  	cc.closeIfIdle()
  8204  }
  8205  
  8206  func (cc *http2ClientConn) closeConn() {
  8207  	t := time.AfterFunc(250*time.Millisecond, cc.forceCloseConn)
  8208  	defer t.Stop()
  8209  	cc.tconn.Close()
  8210  }
  8211  
  8212  // A tls.Conn.Close can hang for a long time if the peer is unresponsive.
  8213  // Try to shut it down more aggressively.
  8214  func (cc *http2ClientConn) forceCloseConn() {
  8215  	tc, ok := cc.tconn.(*tls.Conn)
  8216  	if !ok {
  8217  		return
  8218  	}
  8219  	if nc := tc.NetConn(); nc != nil {
  8220  		nc.Close()
  8221  	}
  8222  }
  8223  
  8224  func (cc *http2ClientConn) closeIfIdle() {
  8225  	cc.mu.Lock()
  8226  	if len(cc.streams) > 0 || cc.streamsReserved > 0 {
  8227  		cc.mu.Unlock()
  8228  		return
  8229  	}
  8230  	cc.closed = true
  8231  	nextID := cc.nextStreamID
  8232  	// TODO: do clients send GOAWAY too? maybe? Just Close:
  8233  	cc.mu.Unlock()
  8234  
  8235  	if http2VerboseLogs {
  8236  		cc.vlogf("http2: Transport closing idle conn %p (forSingleUse=%v, maxStream=%v)", cc, cc.singleUse, nextID-2)
  8237  	}
  8238  	cc.closeConn()
  8239  }
  8240  
  8241  func (cc *http2ClientConn) isDoNotReuseAndIdle() bool {
  8242  	cc.mu.Lock()
  8243  	defer cc.mu.Unlock()
  8244  	return cc.doNotReuse && len(cc.streams) == 0
  8245  }
  8246  
  8247  var http2shutdownEnterWaitStateHook = func() {}
  8248  
  8249  // Shutdown gracefully closes the client connection, waiting for running streams to complete.
  8250  func (cc *http2ClientConn) Shutdown(ctx context.Context) error {
  8251  	if err := cc.sendGoAway(); err != nil {
  8252  		return err
  8253  	}
  8254  	// Wait for all in-flight streams to complete or connection to close
  8255  	done := make(chan struct{})
  8256  	cancelled := false // guarded by cc.mu
  8257  	go func() {
  8258  		cc.t.markNewGoroutine()
  8259  		cc.mu.Lock()
  8260  		defer cc.mu.Unlock()
  8261  		for {
  8262  			if len(cc.streams) == 0 || cc.closed {
  8263  				cc.closed = true
  8264  				close(done)
  8265  				break
  8266  			}
  8267  			if cancelled {
  8268  				break
  8269  			}
  8270  			cc.cond.Wait()
  8271  		}
  8272  	}()
  8273  	http2shutdownEnterWaitStateHook()
  8274  	select {
  8275  	case <-done:
  8276  		cc.closeConn()
  8277  		return nil
  8278  	case <-ctx.Done():
  8279  		cc.mu.Lock()
  8280  		// Free the goroutine above
  8281  		cancelled = true
  8282  		cc.cond.Broadcast()
  8283  		cc.mu.Unlock()
  8284  		return ctx.Err()
  8285  	}
  8286  }
  8287  
  8288  func (cc *http2ClientConn) sendGoAway() error {
  8289  	cc.mu.Lock()
  8290  	closing := cc.closing
  8291  	cc.closing = true
  8292  	maxStreamID := cc.nextStreamID
  8293  	cc.mu.Unlock()
  8294  	if closing {
  8295  		// GOAWAY sent already
  8296  		return nil
  8297  	}
  8298  
  8299  	cc.wmu.Lock()
  8300  	defer cc.wmu.Unlock()
  8301  	// Send a graceful shutdown frame to server
  8302  	if err := cc.fr.WriteGoAway(maxStreamID, http2ErrCodeNo, nil); err != nil {
  8303  		return err
  8304  	}
  8305  	if err := cc.bw.Flush(); err != nil {
  8306  		return err
  8307  	}
  8308  	// Prevent new requests
  8309  	return nil
  8310  }
  8311  
  8312  // closes the client connection immediately. In-flight requests are interrupted.
  8313  // err is sent to streams.
  8314  func (cc *http2ClientConn) closeForError(err error) {
  8315  	cc.mu.Lock()
  8316  	cc.closed = true
  8317  	for _, cs := range cc.streams {
  8318  		cs.abortStreamLocked(err)
  8319  	}
  8320  	cc.cond.Broadcast()
  8321  	cc.mu.Unlock()
  8322  	cc.closeConn()
  8323  }
  8324  
  8325  // Close closes the client connection immediately.
  8326  //
  8327  // In-flight requests are interrupted. For a graceful shutdown, use Shutdown instead.
  8328  func (cc *http2ClientConn) Close() error {
  8329  	err := errors.New("http2: client connection force closed via ClientConn.Close")
  8330  	cc.closeForError(err)
  8331  	return nil
  8332  }
  8333  
  8334  // closes the client connection immediately. In-flight requests are interrupted.
  8335  func (cc *http2ClientConn) closeForLostPing() {
  8336  	err := errors.New("http2: client connection lost")
  8337  	if f := cc.t.CountError; f != nil {
  8338  		f("conn_close_lost_ping")
  8339  	}
  8340  	cc.closeForError(err)
  8341  }
  8342  
  8343  // errRequestCanceled is a copy of net/http's errRequestCanceled because it's not
  8344  // exported. At least they'll be DeepEqual for h1-vs-h2 comparisons tests.
  8345  var http2errRequestCanceled = errors.New("net/http: request canceled")
  8346  
  8347  func http2commaSeparatedTrailers(req *Request) (string, error) {
  8348  	keys := make([]string, 0, len(req.Trailer))
  8349  	for k := range req.Trailer {
  8350  		k = http2canonicalHeader(k)
  8351  		switch k {
  8352  		case "Transfer-Encoding", "Trailer", "Content-Length":
  8353  			return "", fmt.Errorf("invalid Trailer key %q", k)
  8354  		}
  8355  		keys = append(keys, k)
  8356  	}
  8357  	if len(keys) > 0 {
  8358  		sort.Strings(keys)
  8359  		return strings.Join(keys, ","), nil
  8360  	}
  8361  	return "", nil
  8362  }
  8363  
  8364  func (cc *http2ClientConn) responseHeaderTimeout() time.Duration {
  8365  	if cc.t.t1 != nil {
  8366  		return cc.t.t1.ResponseHeaderTimeout
  8367  	}
  8368  	// No way to do this (yet?) with just an http2.Transport. Probably
  8369  	// no need. Request.Cancel this is the new way. We only need to support
  8370  	// this for compatibility with the old http.Transport fields when
  8371  	// we're doing transparent http2.
  8372  	return 0
  8373  }
  8374  
  8375  // checkConnHeaders checks whether req has any invalid connection-level headers.
  8376  // per RFC 7540 section 8.1.2.2: Connection-Specific Header Fields.
  8377  // Certain headers are special-cased as okay but not transmitted later.
  8378  func http2checkConnHeaders(req *Request) error {
  8379  	if v := req.Header.Get("Upgrade"); v != "" {
  8380  		return fmt.Errorf("http2: invalid Upgrade request header: %q", req.Header["Upgrade"])
  8381  	}
  8382  	if vv := req.Header["Transfer-Encoding"]; len(vv) > 0 && (len(vv) > 1 || vv[0] != "" && vv[0] != "chunked") {
  8383  		return fmt.Errorf("http2: invalid Transfer-Encoding request header: %q", vv)
  8384  	}
  8385  	if vv := req.Header["Connection"]; len(vv) > 0 && (len(vv) > 1 || vv[0] != "" && !http2asciiEqualFold(vv[0], "close") && !http2asciiEqualFold(vv[0], "keep-alive")) {
  8386  		return fmt.Errorf("http2: invalid Connection request header: %q", vv)
  8387  	}
  8388  	return nil
  8389  }
  8390  
  8391  // actualContentLength returns a sanitized version of
  8392  // req.ContentLength, where 0 actually means zero (not unknown) and -1
  8393  // means unknown.
  8394  func http2actualContentLength(req *Request) int64 {
  8395  	if req.Body == nil || req.Body == NoBody {
  8396  		return 0
  8397  	}
  8398  	if req.ContentLength != 0 {
  8399  		return req.ContentLength
  8400  	}
  8401  	return -1
  8402  }
  8403  
  8404  func (cc *http2ClientConn) decrStreamReservations() {
  8405  	cc.mu.Lock()
  8406  	defer cc.mu.Unlock()
  8407  	cc.decrStreamReservationsLocked()
  8408  }
  8409  
  8410  func (cc *http2ClientConn) decrStreamReservationsLocked() {
  8411  	if cc.streamsReserved > 0 {
  8412  		cc.streamsReserved--
  8413  	}
  8414  }
  8415  
  8416  func (cc *http2ClientConn) RoundTrip(req *Request) (*Response, error) {
  8417  	return cc.roundTrip(req, nil)
  8418  }
  8419  
  8420  func (cc *http2ClientConn) roundTrip(req *Request, streamf func(*http2clientStream)) (*Response, error) {
  8421  	ctx := req.Context()
  8422  	cs := &http2clientStream{
  8423  		cc:                   cc,
  8424  		ctx:                  ctx,
  8425  		reqCancel:            req.Cancel,
  8426  		isHead:               req.Method == "HEAD",
  8427  		reqBody:              req.Body,
  8428  		reqBodyContentLength: http2actualContentLength(req),
  8429  		trace:                httptrace.ContextClientTrace(ctx),
  8430  		peerClosed:           make(chan struct{}),
  8431  		abort:                make(chan struct{}),
  8432  		respHeaderRecv:       make(chan struct{}),
  8433  		donec:                make(chan struct{}),
  8434  	}
  8435  
  8436  	// TODO(bradfitz): this is a copy of the logic in net/http. Unify somewhere?
  8437  	if !cc.t.disableCompression() &&
  8438  		req.Header.Get("Accept-Encoding") == "" &&
  8439  		req.Header.Get("Range") == "" &&
  8440  		!cs.isHead {
  8441  		// Request gzip only, not deflate. Deflate is ambiguous and
  8442  		// not as universally supported anyway.
  8443  		// See: https://zlib.net/zlib_faq.html#faq39
  8444  		//
  8445  		// Note that we don't request this for HEAD requests,
  8446  		// due to a bug in nginx:
  8447  		//   http://trac.nginx.org/nginx/ticket/358
  8448  		//   https://golang.org/issue/5522
  8449  		//
  8450  		// We don't request gzip if the request is for a range, since
  8451  		// auto-decoding a portion of a gzipped document will just fail
  8452  		// anyway. See https://golang.org/issue/8923
  8453  		cs.requestedGzip = true
  8454  	}
  8455  
  8456  	go cs.doRequest(req, streamf)
  8457  
  8458  	waitDone := func() error {
  8459  		select {
  8460  		case <-cs.donec:
  8461  			return nil
  8462  		case <-ctx.Done():
  8463  			return ctx.Err()
  8464  		case <-cs.reqCancel:
  8465  			return http2errRequestCanceled
  8466  		}
  8467  	}
  8468  
  8469  	handleResponseHeaders := func() (*Response, error) {
  8470  		res := cs.res
  8471  		if res.StatusCode > 299 {
  8472  			// On error or status code 3xx, 4xx, 5xx, etc abort any
  8473  			// ongoing write, assuming that the server doesn't care
  8474  			// about our request body. If the server replied with 1xx or
  8475  			// 2xx, however, then assume the server DOES potentially
  8476  			// want our body (e.g. full-duplex streaming:
  8477  			// golang.org/issue/13444). If it turns out the server
  8478  			// doesn't, they'll RST_STREAM us soon enough. This is a
  8479  			// heuristic to avoid adding knobs to Transport. Hopefully
  8480  			// we can keep it.
  8481  			cs.abortRequestBodyWrite()
  8482  		}
  8483  		res.Request = req
  8484  		res.TLS = cc.tlsState
  8485  		if res.Body == http2noBody && http2actualContentLength(req) == 0 {
  8486  			// If there isn't a request or response body still being
  8487  			// written, then wait for the stream to be closed before
  8488  			// RoundTrip returns.
  8489  			if err := waitDone(); err != nil {
  8490  				return nil, err
  8491  			}
  8492  		}
  8493  		return res, nil
  8494  	}
  8495  
  8496  	cancelRequest := func(cs *http2clientStream, err error) error {
  8497  		cs.cc.mu.Lock()
  8498  		bodyClosed := cs.reqBodyClosed
  8499  		cs.cc.mu.Unlock()
  8500  		// Wait for the request body to be closed.
  8501  		//
  8502  		// If nothing closed the body before now, abortStreamLocked
  8503  		// will have started a goroutine to close it.
  8504  		//
  8505  		// Closing the body before returning avoids a race condition
  8506  		// with net/http checking its readTrackingBody to see if the
  8507  		// body was read from or closed. See golang/go#60041.
  8508  		//
  8509  		// The body is closed in a separate goroutine without the
  8510  		// connection mutex held, but dropping the mutex before waiting
  8511  		// will keep us from holding it indefinitely if the body
  8512  		// close is slow for some reason.
  8513  		if bodyClosed != nil {
  8514  			<-bodyClosed
  8515  		}
  8516  		return err
  8517  	}
  8518  
  8519  	for {
  8520  		select {
  8521  		case <-cs.respHeaderRecv:
  8522  			return handleResponseHeaders()
  8523  		case <-cs.abort:
  8524  			select {
  8525  			case <-cs.respHeaderRecv:
  8526  				// If both cs.respHeaderRecv and cs.abort are signaling,
  8527  				// pick respHeaderRecv. The server probably wrote the
  8528  				// response and immediately reset the stream.
  8529  				// golang.org/issue/49645
  8530  				return handleResponseHeaders()
  8531  			default:
  8532  				waitDone()
  8533  				return nil, cs.abortErr
  8534  			}
  8535  		case <-ctx.Done():
  8536  			err := ctx.Err()
  8537  			cs.abortStream(err)
  8538  			return nil, cancelRequest(cs, err)
  8539  		case <-cs.reqCancel:
  8540  			cs.abortStream(http2errRequestCanceled)
  8541  			return nil, cancelRequest(cs, http2errRequestCanceled)
  8542  		}
  8543  	}
  8544  }
  8545  
  8546  // doRequest runs for the duration of the request lifetime.
  8547  //
  8548  // It sends the request and performs post-request cleanup (closing Request.Body, etc.).
  8549  func (cs *http2clientStream) doRequest(req *Request, streamf func(*http2clientStream)) {
  8550  	cs.cc.t.markNewGoroutine()
  8551  	err := cs.writeRequest(req, streamf)
  8552  	cs.cleanupWriteRequest(err)
  8553  }
  8554  
  8555  // writeRequest sends a request.
  8556  //
  8557  // It returns nil after the request is written, the response read,
  8558  // and the request stream is half-closed by the peer.
  8559  //
  8560  // It returns non-nil if the request ends otherwise.
  8561  // If the returned error is StreamError, the error Code may be used in resetting the stream.
  8562  func (cs *http2clientStream) writeRequest(req *Request, streamf func(*http2clientStream)) (err error) {
  8563  	cc := cs.cc
  8564  	ctx := cs.ctx
  8565  
  8566  	if err := http2checkConnHeaders(req); err != nil {
  8567  		return err
  8568  	}
  8569  
  8570  	// Acquire the new-request lock by writing to reqHeaderMu.
  8571  	// This lock guards the critical section covering allocating a new stream ID
  8572  	// (requires mu) and creating the stream (requires wmu).
  8573  	if cc.reqHeaderMu == nil {
  8574  		panic("RoundTrip on uninitialized ClientConn") // for tests
  8575  	}
  8576  	select {
  8577  	case cc.reqHeaderMu <- struct{}{}:
  8578  	case <-cs.reqCancel:
  8579  		return http2errRequestCanceled
  8580  	case <-ctx.Done():
  8581  		return ctx.Err()
  8582  	}
  8583  
  8584  	cc.mu.Lock()
  8585  	if cc.idleTimer != nil {
  8586  		cc.idleTimer.Stop()
  8587  	}
  8588  	cc.decrStreamReservationsLocked()
  8589  	if err := cc.awaitOpenSlotForStreamLocked(cs); err != nil {
  8590  		cc.mu.Unlock()
  8591  		<-cc.reqHeaderMu
  8592  		return err
  8593  	}
  8594  	cc.addStreamLocked(cs) // assigns stream ID
  8595  	if http2isConnectionCloseRequest(req) {
  8596  		cc.doNotReuse = true
  8597  	}
  8598  	cc.mu.Unlock()
  8599  
  8600  	if streamf != nil {
  8601  		streamf(cs)
  8602  	}
  8603  
  8604  	continueTimeout := cc.t.expectContinueTimeout()
  8605  	if continueTimeout != 0 {
  8606  		if !httpguts.HeaderValuesContainsToken(req.Header["Expect"], "100-continue") {
  8607  			continueTimeout = 0
  8608  		} else {
  8609  			cs.on100 = make(chan struct{}, 1)
  8610  		}
  8611  	}
  8612  
  8613  	// Past this point (where we send request headers), it is possible for
  8614  	// RoundTrip to return successfully. Since the RoundTrip contract permits
  8615  	// the caller to "mutate or reuse" the Request after closing the Response's Body,
  8616  	// we must take care when referencing the Request from here on.
  8617  	err = cs.encodeAndWriteHeaders(req)
  8618  	<-cc.reqHeaderMu
  8619  	if err != nil {
  8620  		return err
  8621  	}
  8622  
  8623  	hasBody := cs.reqBodyContentLength != 0
  8624  	if !hasBody {
  8625  		cs.sentEndStream = true
  8626  	} else {
  8627  		if continueTimeout != 0 {
  8628  			http2traceWait100Continue(cs.trace)
  8629  			timer := time.NewTimer(continueTimeout)
  8630  			select {
  8631  			case <-timer.C:
  8632  				err = nil
  8633  			case <-cs.on100:
  8634  				err = nil
  8635  			case <-cs.abort:
  8636  				err = cs.abortErr
  8637  			case <-ctx.Done():
  8638  				err = ctx.Err()
  8639  			case <-cs.reqCancel:
  8640  				err = http2errRequestCanceled
  8641  			}
  8642  			timer.Stop()
  8643  			if err != nil {
  8644  				http2traceWroteRequest(cs.trace, err)
  8645  				return err
  8646  			}
  8647  		}
  8648  
  8649  		if err = cs.writeRequestBody(req); err != nil {
  8650  			if err != http2errStopReqBodyWrite {
  8651  				http2traceWroteRequest(cs.trace, err)
  8652  				return err
  8653  			}
  8654  		} else {
  8655  			cs.sentEndStream = true
  8656  		}
  8657  	}
  8658  
  8659  	http2traceWroteRequest(cs.trace, err)
  8660  
  8661  	var respHeaderTimer <-chan time.Time
  8662  	var respHeaderRecv chan struct{}
  8663  	if d := cc.responseHeaderTimeout(); d != 0 {
  8664  		timer := cc.t.newTimer(d)
  8665  		defer timer.Stop()
  8666  		respHeaderTimer = timer.C()
  8667  		respHeaderRecv = cs.respHeaderRecv
  8668  	}
  8669  	// Wait until the peer half-closes its end of the stream,
  8670  	// or until the request is aborted (via context, error, or otherwise),
  8671  	// whichever comes first.
  8672  	for {
  8673  		select {
  8674  		case <-cs.peerClosed:
  8675  			return nil
  8676  		case <-respHeaderTimer:
  8677  			return http2errTimeout
  8678  		case <-respHeaderRecv:
  8679  			respHeaderRecv = nil
  8680  			respHeaderTimer = nil // keep waiting for END_STREAM
  8681  		case <-cs.abort:
  8682  			return cs.abortErr
  8683  		case <-ctx.Done():
  8684  			return ctx.Err()
  8685  		case <-cs.reqCancel:
  8686  			return http2errRequestCanceled
  8687  		}
  8688  	}
  8689  }
  8690  
  8691  func (cs *http2clientStream) encodeAndWriteHeaders(req *Request) error {
  8692  	cc := cs.cc
  8693  	ctx := cs.ctx
  8694  
  8695  	cc.wmu.Lock()
  8696  	defer cc.wmu.Unlock()
  8697  
  8698  	// If the request was canceled while waiting for cc.mu, just quit.
  8699  	select {
  8700  	case <-cs.abort:
  8701  		return cs.abortErr
  8702  	case <-ctx.Done():
  8703  		return ctx.Err()
  8704  	case <-cs.reqCancel:
  8705  		return http2errRequestCanceled
  8706  	default:
  8707  	}
  8708  
  8709  	// Encode headers.
  8710  	//
  8711  	// we send: HEADERS{1}, CONTINUATION{0,} + DATA{0,} (DATA is
  8712  	// sent by writeRequestBody below, along with any Trailers,
  8713  	// again in form HEADERS{1}, CONTINUATION{0,})
  8714  	trailers, err := http2commaSeparatedTrailers(req)
  8715  	if err != nil {
  8716  		return err
  8717  	}
  8718  	hasTrailers := trailers != ""
  8719  	contentLen := http2actualContentLength(req)
  8720  	hasBody := contentLen != 0
  8721  	hdrs, err := cc.encodeHeaders(req, cs.requestedGzip, trailers, contentLen)
  8722  	if err != nil {
  8723  		return err
  8724  	}
  8725  
  8726  	// Write the request.
  8727  	endStream := !hasBody && !hasTrailers
  8728  	cs.sentHeaders = true
  8729  	err = cc.writeHeaders(cs.ID, endStream, int(cc.maxFrameSize), hdrs)
  8730  	http2traceWroteHeaders(cs.trace)
  8731  	return err
  8732  }
  8733  
  8734  // cleanupWriteRequest performs post-request tasks.
  8735  //
  8736  // If err (the result of writeRequest) is non-nil and the stream is not closed,
  8737  // cleanupWriteRequest will send a reset to the peer.
  8738  func (cs *http2clientStream) cleanupWriteRequest(err error) {
  8739  	cc := cs.cc
  8740  
  8741  	if cs.ID == 0 {
  8742  		// We were canceled before creating the stream, so return our reservation.
  8743  		cc.decrStreamReservations()
  8744  	}
  8745  
  8746  	// TODO: write h12Compare test showing whether
  8747  	// Request.Body is closed by the Transport,
  8748  	// and in multiple cases: server replies <=299 and >299
  8749  	// while still writing request body
  8750  	cc.mu.Lock()
  8751  	mustCloseBody := false
  8752  	if cs.reqBody != nil && cs.reqBodyClosed == nil {
  8753  		mustCloseBody = true
  8754  		cs.reqBodyClosed = make(chan struct{})
  8755  	}
  8756  	bodyClosed := cs.reqBodyClosed
  8757  	cc.mu.Unlock()
  8758  	if mustCloseBody {
  8759  		cs.reqBody.Close()
  8760  		close(bodyClosed)
  8761  	}
  8762  	if bodyClosed != nil {
  8763  		<-bodyClosed
  8764  	}
  8765  
  8766  	if err != nil && cs.sentEndStream {
  8767  		// If the connection is closed immediately after the response is read,
  8768  		// we may be aborted before finishing up here. If the stream was closed
  8769  		// cleanly on both sides, there is no error.
  8770  		select {
  8771  		case <-cs.peerClosed:
  8772  			err = nil
  8773  		default:
  8774  		}
  8775  	}
  8776  	if err != nil {
  8777  		cs.abortStream(err) // possibly redundant, but harmless
  8778  		if cs.sentHeaders {
  8779  			if se, ok := err.(http2StreamError); ok {
  8780  				if se.Cause != http2errFromPeer {
  8781  					cc.writeStreamReset(cs.ID, se.Code, err)
  8782  				}
  8783  			} else {
  8784  				cc.writeStreamReset(cs.ID, http2ErrCodeCancel, err)
  8785  			}
  8786  		}
  8787  		cs.bufPipe.CloseWithError(err) // no-op if already closed
  8788  	} else {
  8789  		if cs.sentHeaders && !cs.sentEndStream {
  8790  			cc.writeStreamReset(cs.ID, http2ErrCodeNo, nil)
  8791  		}
  8792  		cs.bufPipe.CloseWithError(http2errRequestCanceled)
  8793  	}
  8794  	if cs.ID != 0 {
  8795  		cc.forgetStreamID(cs.ID)
  8796  	}
  8797  
  8798  	cc.wmu.Lock()
  8799  	werr := cc.werr
  8800  	cc.wmu.Unlock()
  8801  	if werr != nil {
  8802  		cc.Close()
  8803  	}
  8804  
  8805  	close(cs.donec)
  8806  }
  8807  
  8808  // awaitOpenSlotForStreamLocked waits until len(streams) < maxConcurrentStreams.
  8809  // Must hold cc.mu.
  8810  func (cc *http2ClientConn) awaitOpenSlotForStreamLocked(cs *http2clientStream) error {
  8811  	for {
  8812  		cc.lastActive = time.Now()
  8813  		if cc.closed || !cc.canTakeNewRequestLocked() {
  8814  			return http2errClientConnUnusable
  8815  		}
  8816  		cc.lastIdle = time.Time{}
  8817  		if int64(len(cc.streams)) < int64(cc.maxConcurrentStreams) {
  8818  			return nil
  8819  		}
  8820  		cc.pendingRequests++
  8821  		cc.cond.Wait()
  8822  		cc.pendingRequests--
  8823  		select {
  8824  		case <-cs.abort:
  8825  			return cs.abortErr
  8826  		default:
  8827  		}
  8828  	}
  8829  }
  8830  
  8831  // requires cc.wmu be held
  8832  func (cc *http2ClientConn) writeHeaders(streamID uint32, endStream bool, maxFrameSize int, hdrs []byte) error {
  8833  	first := true // first frame written (HEADERS is first, then CONTINUATION)
  8834  	for len(hdrs) > 0 && cc.werr == nil {
  8835  		chunk := hdrs
  8836  		if len(chunk) > maxFrameSize {
  8837  			chunk = chunk[:maxFrameSize]
  8838  		}
  8839  		hdrs = hdrs[len(chunk):]
  8840  		endHeaders := len(hdrs) == 0
  8841  		if first {
  8842  			cc.fr.WriteHeaders(http2HeadersFrameParam{
  8843  				StreamID:      streamID,
  8844  				BlockFragment: chunk,
  8845  				EndStream:     endStream,
  8846  				EndHeaders:    endHeaders,
  8847  			})
  8848  			first = false
  8849  		} else {
  8850  			cc.fr.WriteContinuation(streamID, endHeaders, chunk)
  8851  		}
  8852  	}
  8853  	cc.bw.Flush()
  8854  	return cc.werr
  8855  }
  8856  
  8857  // internal error values; they don't escape to callers
  8858  var (
  8859  	// abort request body write; don't send cancel
  8860  	http2errStopReqBodyWrite = errors.New("http2: aborting request body write")
  8861  
  8862  	// abort request body write, but send stream reset of cancel.
  8863  	http2errStopReqBodyWriteAndCancel = errors.New("http2: canceling request")
  8864  
  8865  	http2errReqBodyTooLong = errors.New("http2: request body larger than specified content length")
  8866  )
  8867  
  8868  // frameScratchBufferLen returns the length of a buffer to use for
  8869  // outgoing request bodies to read/write to/from.
  8870  //
  8871  // It returns max(1, min(peer's advertised max frame size,
  8872  // Request.ContentLength+1, 512KB)).
  8873  func (cs *http2clientStream) frameScratchBufferLen(maxFrameSize int) int {
  8874  	const max = 512 << 10
  8875  	n := int64(maxFrameSize)
  8876  	if n > max {
  8877  		n = max
  8878  	}
  8879  	if cl := cs.reqBodyContentLength; cl != -1 && cl+1 < n {
  8880  		// Add an extra byte past the declared content-length to
  8881  		// give the caller's Request.Body io.Reader a chance to
  8882  		// give us more bytes than they declared, so we can catch it
  8883  		// early.
  8884  		n = cl + 1
  8885  	}
  8886  	if n < 1 {
  8887  		return 1
  8888  	}
  8889  	return int(n) // doesn't truncate; max is 512K
  8890  }
  8891  
  8892  // Seven bufPools manage different frame sizes. This helps to avoid scenarios where long-running
  8893  // streaming requests using small frame sizes occupy large buffers initially allocated for prior
  8894  // requests needing big buffers. The size ranges are as follows:
  8895  // {0 KB, 16 KB], {16 KB, 32 KB], {32 KB, 64 KB], {64 KB, 128 KB], {128 KB, 256 KB],
  8896  // {256 KB, 512 KB], {512 KB, infinity}
  8897  // In practice, the maximum scratch buffer size should not exceed 512 KB due to
  8898  // frameScratchBufferLen(maxFrameSize), thus the "infinity pool" should never be used.
  8899  // It exists mainly as a safety measure, for potential future increases in max buffer size.
  8900  var http2bufPools [7]sync.Pool // of *[]byte
  8901  
  8902  func http2bufPoolIndex(size int) int {
  8903  	if size <= 16384 {
  8904  		return 0
  8905  	}
  8906  	size -= 1
  8907  	bits := bits.Len(uint(size))
  8908  	index := bits - 14
  8909  	if index >= len(http2bufPools) {
  8910  		return len(http2bufPools) - 1
  8911  	}
  8912  	return index
  8913  }
  8914  
  8915  func (cs *http2clientStream) writeRequestBody(req *Request) (err error) {
  8916  	cc := cs.cc
  8917  	body := cs.reqBody
  8918  	sentEnd := false // whether we sent the final DATA frame w/ END_STREAM
  8919  
  8920  	hasTrailers := req.Trailer != nil
  8921  	remainLen := cs.reqBodyContentLength
  8922  	hasContentLen := remainLen != -1
  8923  
  8924  	cc.mu.Lock()
  8925  	maxFrameSize := int(cc.maxFrameSize)
  8926  	cc.mu.Unlock()
  8927  
  8928  	// Scratch buffer for reading into & writing from.
  8929  	scratchLen := cs.frameScratchBufferLen(maxFrameSize)
  8930  	var buf []byte
  8931  	index := http2bufPoolIndex(scratchLen)
  8932  	if bp, ok := http2bufPools[index].Get().(*[]byte); ok && len(*bp) >= scratchLen {
  8933  		defer http2bufPools[index].Put(bp)
  8934  		buf = *bp
  8935  	} else {
  8936  		buf = make([]byte, scratchLen)
  8937  		defer http2bufPools[index].Put(&buf)
  8938  	}
  8939  
  8940  	var sawEOF bool
  8941  	for !sawEOF {
  8942  		n, err := body.Read(buf)
  8943  		if hasContentLen {
  8944  			remainLen -= int64(n)
  8945  			if remainLen == 0 && err == nil {
  8946  				// The request body's Content-Length was predeclared and
  8947  				// we just finished reading it all, but the underlying io.Reader
  8948  				// returned the final chunk with a nil error (which is one of
  8949  				// the two valid things a Reader can do at EOF). Because we'd prefer
  8950  				// to send the END_STREAM bit early, double-check that we're actually
  8951  				// at EOF. Subsequent reads should return (0, EOF) at this point.
  8952  				// If either value is different, we return an error in one of two ways below.
  8953  				var scratch [1]byte
  8954  				var n1 int
  8955  				n1, err = body.Read(scratch[:])
  8956  				remainLen -= int64(n1)
  8957  			}
  8958  			if remainLen < 0 {
  8959  				err = http2errReqBodyTooLong
  8960  				return err
  8961  			}
  8962  		}
  8963  		if err != nil {
  8964  			cc.mu.Lock()
  8965  			bodyClosed := cs.reqBodyClosed != nil
  8966  			cc.mu.Unlock()
  8967  			switch {
  8968  			case bodyClosed:
  8969  				return http2errStopReqBodyWrite
  8970  			case err == io.EOF:
  8971  				sawEOF = true
  8972  				err = nil
  8973  			default:
  8974  				return err
  8975  			}
  8976  		}
  8977  
  8978  		remain := buf[:n]
  8979  		for len(remain) > 0 && err == nil {
  8980  			var allowed int32
  8981  			allowed, err = cs.awaitFlowControl(len(remain))
  8982  			if err != nil {
  8983  				return err
  8984  			}
  8985  			cc.wmu.Lock()
  8986  			data := remain[:allowed]
  8987  			remain = remain[allowed:]
  8988  			sentEnd = sawEOF && len(remain) == 0 && !hasTrailers
  8989  			err = cc.fr.WriteData(cs.ID, sentEnd, data)
  8990  			if err == nil {
  8991  				// TODO(bradfitz): this flush is for latency, not bandwidth.
  8992  				// Most requests won't need this. Make this opt-in or
  8993  				// opt-out?  Use some heuristic on the body type? Nagel-like
  8994  				// timers?  Based on 'n'? Only last chunk of this for loop,
  8995  				// unless flow control tokens are low? For now, always.
  8996  				// If we change this, see comment below.
  8997  				err = cc.bw.Flush()
  8998  			}
  8999  			cc.wmu.Unlock()
  9000  		}
  9001  		if err != nil {
  9002  			return err
  9003  		}
  9004  	}
  9005  
  9006  	if sentEnd {
  9007  		// Already sent END_STREAM (which implies we have no
  9008  		// trailers) and flushed, because currently all
  9009  		// WriteData frames above get a flush. So we're done.
  9010  		return nil
  9011  	}
  9012  
  9013  	// Since the RoundTrip contract permits the caller to "mutate or reuse"
  9014  	// a request after the Response's Body is closed, verify that this hasn't
  9015  	// happened before accessing the trailers.
  9016  	cc.mu.Lock()
  9017  	trailer := req.Trailer
  9018  	err = cs.abortErr
  9019  	cc.mu.Unlock()
  9020  	if err != nil {
  9021  		return err
  9022  	}
  9023  
  9024  	cc.wmu.Lock()
  9025  	defer cc.wmu.Unlock()
  9026  	var trls []byte
  9027  	if len(trailer) > 0 {
  9028  		trls, err = cc.encodeTrailers(trailer)
  9029  		if err != nil {
  9030  			return err
  9031  		}
  9032  	}
  9033  
  9034  	// Two ways to send END_STREAM: either with trailers, or
  9035  	// with an empty DATA frame.
  9036  	if len(trls) > 0 {
  9037  		err = cc.writeHeaders(cs.ID, true, maxFrameSize, trls)
  9038  	} else {
  9039  		err = cc.fr.WriteData(cs.ID, true, nil)
  9040  	}
  9041  	if ferr := cc.bw.Flush(); ferr != nil && err == nil {
  9042  		err = ferr
  9043  	}
  9044  	return err
  9045  }
  9046  
  9047  // awaitFlowControl waits for [1, min(maxBytes, cc.cs.maxFrameSize)] flow
  9048  // control tokens from the server.
  9049  // It returns either the non-zero number of tokens taken or an error
  9050  // if the stream is dead.
  9051  func (cs *http2clientStream) awaitFlowControl(maxBytes int) (taken int32, err error) {
  9052  	cc := cs.cc
  9053  	ctx := cs.ctx
  9054  	cc.mu.Lock()
  9055  	defer cc.mu.Unlock()
  9056  	for {
  9057  		if cc.closed {
  9058  			return 0, http2errClientConnClosed
  9059  		}
  9060  		if cs.reqBodyClosed != nil {
  9061  			return 0, http2errStopReqBodyWrite
  9062  		}
  9063  		select {
  9064  		case <-cs.abort:
  9065  			return 0, cs.abortErr
  9066  		case <-ctx.Done():
  9067  			return 0, ctx.Err()
  9068  		case <-cs.reqCancel:
  9069  			return 0, http2errRequestCanceled
  9070  		default:
  9071  		}
  9072  		if a := cs.flow.available(); a > 0 {
  9073  			take := a
  9074  			if int(take) > maxBytes {
  9075  
  9076  				take = int32(maxBytes) // can't truncate int; take is int32
  9077  			}
  9078  			if take > int32(cc.maxFrameSize) {
  9079  				take = int32(cc.maxFrameSize)
  9080  			}
  9081  			cs.flow.take(take)
  9082  			return take, nil
  9083  		}
  9084  		cc.cond.Wait()
  9085  	}
  9086  }
  9087  
  9088  func http2validateHeaders(hdrs Header) string {
  9089  	for k, vv := range hdrs {
  9090  		if !httpguts.ValidHeaderFieldName(k) {
  9091  			return fmt.Sprintf("name %q", k)
  9092  		}
  9093  		for _, v := range vv {
  9094  			if !httpguts.ValidHeaderFieldValue(v) {
  9095  				// Don't include the value in the error,
  9096  				// because it may be sensitive.
  9097  				return fmt.Sprintf("value for header %q", k)
  9098  			}
  9099  		}
  9100  	}
  9101  	return ""
  9102  }
  9103  
  9104  var http2errNilRequestURL = errors.New("http2: Request.URI is nil")
  9105  
  9106  // requires cc.wmu be held.
  9107  func (cc *http2ClientConn) encodeHeaders(req *Request, addGzipHeader bool, trailers string, contentLength int64) ([]byte, error) {
  9108  	cc.hbuf.Reset()
  9109  	if req.URL == nil {
  9110  		return nil, http2errNilRequestURL
  9111  	}
  9112  
  9113  	host := req.Host
  9114  	if host == "" {
  9115  		host = req.URL.Host
  9116  	}
  9117  	host, err := httpguts.PunycodeHostPort(host)
  9118  	if err != nil {
  9119  		return nil, err
  9120  	}
  9121  	if !httpguts.ValidHostHeader(host) {
  9122  		return nil, errors.New("http2: invalid Host header")
  9123  	}
  9124  
  9125  	var path string
  9126  	if req.Method != "CONNECT" {
  9127  		path = req.URL.RequestURI()
  9128  		if !http2validPseudoPath(path) {
  9129  			orig := path
  9130  			path = strings.TrimPrefix(path, req.URL.Scheme+"://"+host)
  9131  			if !http2validPseudoPath(path) {
  9132  				if req.URL.Opaque != "" {
  9133  					return nil, fmt.Errorf("invalid request :path %q from URL.Opaque = %q", orig, req.URL.Opaque)
  9134  				} else {
  9135  					return nil, fmt.Errorf("invalid request :path %q", orig)
  9136  				}
  9137  			}
  9138  		}
  9139  	}
  9140  
  9141  	// Check for any invalid headers+trailers and return an error before we
  9142  	// potentially pollute our hpack state. (We want to be able to
  9143  	// continue to reuse the hpack encoder for future requests)
  9144  	if err := http2validateHeaders(req.Header); err != "" {
  9145  		return nil, fmt.Errorf("invalid HTTP header %s", err)
  9146  	}
  9147  	if err := http2validateHeaders(req.Trailer); err != "" {
  9148  		return nil, fmt.Errorf("invalid HTTP trailer %s", err)
  9149  	}
  9150  
  9151  	enumerateHeaders := func(f func(name, value string)) {
  9152  		// 8.1.2.3 Request Pseudo-Header Fields
  9153  		// The :path pseudo-header field includes the path and query parts of the
  9154  		// target URI (the path-absolute production and optionally a '?' character
  9155  		// followed by the query production, see Sections 3.3 and 3.4 of
  9156  		// [RFC3986]).
  9157  		f(":authority", host)
  9158  		m := req.Method
  9159  		if m == "" {
  9160  			m = MethodGet
  9161  		}
  9162  		f(":method", m)
  9163  		if req.Method != "CONNECT" {
  9164  			f(":path", path)
  9165  			f(":scheme", req.URL.Scheme)
  9166  		}
  9167  		if trailers != "" {
  9168  			f("trailer", trailers)
  9169  		}
  9170  
  9171  		var didUA bool
  9172  		for k, vv := range req.Header {
  9173  			if http2asciiEqualFold(k, "host") || http2asciiEqualFold(k, "content-length") {
  9174  				// Host is :authority, already sent.
  9175  				// Content-Length is automatic, set below.
  9176  				continue
  9177  			} else if http2asciiEqualFold(k, "connection") ||
  9178  				http2asciiEqualFold(k, "proxy-connection") ||
  9179  				http2asciiEqualFold(k, "transfer-encoding") ||
  9180  				http2asciiEqualFold(k, "upgrade") ||
  9181  				http2asciiEqualFold(k, "keep-alive") {
  9182  				// Per 8.1.2.2 Connection-Specific Header
  9183  				// Fields, don't send connection-specific
  9184  				// fields. We have already checked if any
  9185  				// are error-worthy so just ignore the rest.
  9186  				continue
  9187  			} else if http2asciiEqualFold(k, "user-agent") {
  9188  				// Match Go's http1 behavior: at most one
  9189  				// User-Agent. If set to nil or empty string,
  9190  				// then omit it. Otherwise if not mentioned,
  9191  				// include the default (below).
  9192  				didUA = true
  9193  				if len(vv) < 1 {
  9194  					continue
  9195  				}
  9196  				vv = vv[:1]
  9197  				if vv[0] == "" {
  9198  					continue
  9199  				}
  9200  			} else if http2asciiEqualFold(k, "cookie") {
  9201  				// Per 8.1.2.5 To allow for better compression efficiency, the
  9202  				// Cookie header field MAY be split into separate header fields,
  9203  				// each with one or more cookie-pairs.
  9204  				for _, v := range vv {
  9205  					for {
  9206  						p := strings.IndexByte(v, ';')
  9207  						if p < 0 {
  9208  							break
  9209  						}
  9210  						f("cookie", v[:p])
  9211  						p++
  9212  						// strip space after semicolon if any.
  9213  						for p+1 <= len(v) && v[p] == ' ' {
  9214  							p++
  9215  						}
  9216  						v = v[p:]
  9217  					}
  9218  					if len(v) > 0 {
  9219  						f("cookie", v)
  9220  					}
  9221  				}
  9222  				continue
  9223  			}
  9224  
  9225  			for _, v := range vv {
  9226  				f(k, v)
  9227  			}
  9228  		}
  9229  		if http2shouldSendReqContentLength(req.Method, contentLength) {
  9230  			f("content-length", strconv.FormatInt(contentLength, 10))
  9231  		}
  9232  		if addGzipHeader {
  9233  			f("accept-encoding", "gzip")
  9234  		}
  9235  		if !didUA {
  9236  			f("user-agent", http2defaultUserAgent)
  9237  		}
  9238  	}
  9239  
  9240  	// Do a first pass over the headers counting bytes to ensure
  9241  	// we don't exceed cc.peerMaxHeaderListSize. This is done as a
  9242  	// separate pass before encoding the headers to prevent
  9243  	// modifying the hpack state.
  9244  	hlSize := uint64(0)
  9245  	enumerateHeaders(func(name, value string) {
  9246  		hf := hpack.HeaderField{Name: name, Value: value}
  9247  		hlSize += uint64(hf.Size())
  9248  	})
  9249  
  9250  	if hlSize > cc.peerMaxHeaderListSize {
  9251  		return nil, http2errRequestHeaderListSize
  9252  	}
  9253  
  9254  	trace := httptrace.ContextClientTrace(req.Context())
  9255  	traceHeaders := http2traceHasWroteHeaderField(trace)
  9256  
  9257  	// Header list size is ok. Write the headers.
  9258  	enumerateHeaders(func(name, value string) {
  9259  		name, ascii := http2lowerHeader(name)
  9260  		if !ascii {
  9261  			// Skip writing invalid headers. Per RFC 7540, Section 8.1.2, header
  9262  			// field names have to be ASCII characters (just as in HTTP/1.x).
  9263  			return
  9264  		}
  9265  		cc.writeHeader(name, value)
  9266  		if traceHeaders {
  9267  			http2traceWroteHeaderField(trace, name, value)
  9268  		}
  9269  	})
  9270  
  9271  	return cc.hbuf.Bytes(), nil
  9272  }
  9273  
  9274  // shouldSendReqContentLength reports whether the http2.Transport should send
  9275  // a "content-length" request header. This logic is basically a copy of the net/http
  9276  // transferWriter.shouldSendContentLength.
  9277  // The contentLength is the corrected contentLength (so 0 means actually 0, not unknown).
  9278  // -1 means unknown.
  9279  func http2shouldSendReqContentLength(method string, contentLength int64) bool {
  9280  	if contentLength > 0 {
  9281  		return true
  9282  	}
  9283  	if contentLength < 0 {
  9284  		return false
  9285  	}
  9286  	// For zero bodies, whether we send a content-length depends on the method.
  9287  	// It also kinda doesn't matter for http2 either way, with END_STREAM.
  9288  	switch method {
  9289  	case "POST", "PUT", "PATCH":
  9290  		return true
  9291  	default:
  9292  		return false
  9293  	}
  9294  }
  9295  
  9296  // requires cc.wmu be held.
  9297  func (cc *http2ClientConn) encodeTrailers(trailer Header) ([]byte, error) {
  9298  	cc.hbuf.Reset()
  9299  
  9300  	hlSize := uint64(0)
  9301  	for k, vv := range trailer {
  9302  		for _, v := range vv {
  9303  			hf := hpack.HeaderField{Name: k, Value: v}
  9304  			hlSize += uint64(hf.Size())
  9305  		}
  9306  	}
  9307  	if hlSize > cc.peerMaxHeaderListSize {
  9308  		return nil, http2errRequestHeaderListSize
  9309  	}
  9310  
  9311  	for k, vv := range trailer {
  9312  		lowKey, ascii := http2lowerHeader(k)
  9313  		if !ascii {
  9314  			// Skip writing invalid headers. Per RFC 7540, Section 8.1.2, header
  9315  			// field names have to be ASCII characters (just as in HTTP/1.x).
  9316  			continue
  9317  		}
  9318  		// Transfer-Encoding, etc.. have already been filtered at the
  9319  		// start of RoundTrip
  9320  		for _, v := range vv {
  9321  			cc.writeHeader(lowKey, v)
  9322  		}
  9323  	}
  9324  	return cc.hbuf.Bytes(), nil
  9325  }
  9326  
  9327  func (cc *http2ClientConn) writeHeader(name, value string) {
  9328  	if http2VerboseLogs {
  9329  		log.Printf("http2: Transport encoding header %q = %q", name, value)
  9330  	}
  9331  	cc.henc.WriteField(hpack.HeaderField{Name: name, Value: value})
  9332  }
  9333  
  9334  type http2resAndError struct {
  9335  	_   http2incomparable
  9336  	res *Response
  9337  	err error
  9338  }
  9339  
  9340  // requires cc.mu be held.
  9341  func (cc *http2ClientConn) addStreamLocked(cs *http2clientStream) {
  9342  	cs.flow.add(int32(cc.initialWindowSize))
  9343  	cs.flow.setConnFlow(&cc.flow)
  9344  	cs.inflow.init(http2transportDefaultStreamFlow)
  9345  	cs.ID = cc.nextStreamID
  9346  	cc.nextStreamID += 2
  9347  	cc.streams[cs.ID] = cs
  9348  	if cs.ID == 0 {
  9349  		panic("assigned stream ID 0")
  9350  	}
  9351  }
  9352  
  9353  func (cc *http2ClientConn) forgetStreamID(id uint32) {
  9354  	cc.mu.Lock()
  9355  	slen := len(cc.streams)
  9356  	delete(cc.streams, id)
  9357  	if len(cc.streams) != slen-1 {
  9358  		panic("forgetting unknown stream id")
  9359  	}
  9360  	cc.lastActive = time.Now()
  9361  	if len(cc.streams) == 0 && cc.idleTimer != nil {
  9362  		cc.idleTimer.Reset(cc.idleTimeout)
  9363  		cc.lastIdle = time.Now()
  9364  	}
  9365  	// Wake up writeRequestBody via clientStream.awaitFlowControl and
  9366  	// wake up RoundTrip if there is a pending request.
  9367  	cc.cond.Broadcast()
  9368  
  9369  	closeOnIdle := cc.singleUse || cc.doNotReuse || cc.t.disableKeepAlives() || cc.goAway != nil
  9370  	if closeOnIdle && cc.streamsReserved == 0 && len(cc.streams) == 0 {
  9371  		if http2VerboseLogs {
  9372  			cc.vlogf("http2: Transport closing idle conn %p (forSingleUse=%v, maxStream=%v)", cc, cc.singleUse, cc.nextStreamID-2)
  9373  		}
  9374  		cc.closed = true
  9375  		defer cc.closeConn()
  9376  	}
  9377  
  9378  	cc.mu.Unlock()
  9379  }
  9380  
  9381  // clientConnReadLoop is the state owned by the clientConn's frame-reading readLoop.
  9382  type http2clientConnReadLoop struct {
  9383  	_  http2incomparable
  9384  	cc *http2ClientConn
  9385  }
  9386  
  9387  // readLoop runs in its own goroutine and reads and dispatches frames.
  9388  func (cc *http2ClientConn) readLoop() {
  9389  	cc.t.markNewGoroutine()
  9390  	rl := &http2clientConnReadLoop{cc: cc}
  9391  	defer rl.cleanup()
  9392  	cc.readerErr = rl.run()
  9393  	if ce, ok := cc.readerErr.(http2ConnectionError); ok {
  9394  		cc.wmu.Lock()
  9395  		cc.fr.WriteGoAway(0, http2ErrCode(ce), nil)
  9396  		cc.wmu.Unlock()
  9397  	}
  9398  }
  9399  
  9400  // GoAwayError is returned by the Transport when the server closes the
  9401  // TCP connection after sending a GOAWAY frame.
  9402  type http2GoAwayError struct {
  9403  	LastStreamID uint32
  9404  	ErrCode      http2ErrCode
  9405  	DebugData    string
  9406  }
  9407  
  9408  func (e http2GoAwayError) Error() string {
  9409  	return fmt.Sprintf("http2: server sent GOAWAY and closed the connection; LastStreamID=%v, ErrCode=%v, debug=%q",
  9410  		e.LastStreamID, e.ErrCode, e.DebugData)
  9411  }
  9412  
  9413  func http2isEOFOrNetReadError(err error) bool {
  9414  	if err == io.EOF {
  9415  		return true
  9416  	}
  9417  	ne, ok := err.(*net.OpError)
  9418  	return ok && ne.Op == "read"
  9419  }
  9420  
  9421  func (rl *http2clientConnReadLoop) cleanup() {
  9422  	cc := rl.cc
  9423  	cc.t.connPool().MarkDead(cc)
  9424  	defer cc.closeConn()
  9425  	defer close(cc.readerDone)
  9426  
  9427  	if cc.idleTimer != nil {
  9428  		cc.idleTimer.Stop()
  9429  	}
  9430  
  9431  	// Close any response bodies if the server closes prematurely.
  9432  	// TODO: also do this if we've written the headers but not
  9433  	// gotten a response yet.
  9434  	err := cc.readerErr
  9435  	cc.mu.Lock()
  9436  	if cc.goAway != nil && http2isEOFOrNetReadError(err) {
  9437  		err = http2GoAwayError{
  9438  			LastStreamID: cc.goAway.LastStreamID,
  9439  			ErrCode:      cc.goAway.ErrCode,
  9440  			DebugData:    cc.goAwayDebug,
  9441  		}
  9442  	} else if err == io.EOF {
  9443  		err = io.ErrUnexpectedEOF
  9444  	}
  9445  	cc.closed = true
  9446  
  9447  	for _, cs := range cc.streams {
  9448  		select {
  9449  		case <-cs.peerClosed:
  9450  			// The server closed the stream before closing the conn,
  9451  			// so no need to interrupt it.
  9452  		default:
  9453  			cs.abortStreamLocked(err)
  9454  		}
  9455  	}
  9456  	cc.cond.Broadcast()
  9457  	cc.mu.Unlock()
  9458  }
  9459  
  9460  // countReadFrameError calls Transport.CountError with a string
  9461  // representing err.
  9462  func (cc *http2ClientConn) countReadFrameError(err error) {
  9463  	f := cc.t.CountError
  9464  	if f == nil || err == nil {
  9465  		return
  9466  	}
  9467  	if ce, ok := err.(http2ConnectionError); ok {
  9468  		errCode := http2ErrCode(ce)
  9469  		f(fmt.Sprintf("read_frame_conn_error_%s", errCode.stringToken()))
  9470  		return
  9471  	}
  9472  	if errors.Is(err, io.EOF) {
  9473  		f("read_frame_eof")
  9474  		return
  9475  	}
  9476  	if errors.Is(err, io.ErrUnexpectedEOF) {
  9477  		f("read_frame_unexpected_eof")
  9478  		return
  9479  	}
  9480  	if errors.Is(err, http2ErrFrameTooLarge) {
  9481  		f("read_frame_too_large")
  9482  		return
  9483  	}
  9484  	f("read_frame_other")
  9485  }
  9486  
  9487  func (rl *http2clientConnReadLoop) run() error {
  9488  	cc := rl.cc
  9489  	gotSettings := false
  9490  	readIdleTimeout := cc.t.ReadIdleTimeout
  9491  	var t http2timer
  9492  	if readIdleTimeout != 0 {
  9493  		t = cc.t.afterFunc(readIdleTimeout, cc.healthCheck)
  9494  	}
  9495  	for {
  9496  		f, err := cc.fr.ReadFrame()
  9497  		if t != nil {
  9498  			t.Reset(readIdleTimeout)
  9499  		}
  9500  		if err != nil {
  9501  			cc.vlogf("http2: Transport readFrame error on conn %p: (%T) %v", cc, err, err)
  9502  		}
  9503  		if se, ok := err.(http2StreamError); ok {
  9504  			if cs := rl.streamByID(se.StreamID); cs != nil {
  9505  				if se.Cause == nil {
  9506  					se.Cause = cc.fr.errDetail
  9507  				}
  9508  				rl.endStreamError(cs, se)
  9509  			}
  9510  			continue
  9511  		} else if err != nil {
  9512  			cc.countReadFrameError(err)
  9513  			return err
  9514  		}
  9515  		if http2VerboseLogs {
  9516  			cc.vlogf("http2: Transport received %s", http2summarizeFrame(f))
  9517  		}
  9518  		if !gotSettings {
  9519  			if _, ok := f.(*http2SettingsFrame); !ok {
  9520  				cc.logf("protocol error: received %T before a SETTINGS frame", f)
  9521  				return http2ConnectionError(http2ErrCodeProtocol)
  9522  			}
  9523  			gotSettings = true
  9524  		}
  9525  
  9526  		switch f := f.(type) {
  9527  		case *http2MetaHeadersFrame:
  9528  			err = rl.processHeaders(f)
  9529  		case *http2DataFrame:
  9530  			err = rl.processData(f)
  9531  		case *http2GoAwayFrame:
  9532  			err = rl.processGoAway(f)
  9533  		case *http2RSTStreamFrame:
  9534  			err = rl.processResetStream(f)
  9535  		case *http2SettingsFrame:
  9536  			err = rl.processSettings(f)
  9537  		case *http2PushPromiseFrame:
  9538  			err = rl.processPushPromise(f)
  9539  		case *http2WindowUpdateFrame:
  9540  			err = rl.processWindowUpdate(f)
  9541  		case *http2PingFrame:
  9542  			err = rl.processPing(f)
  9543  		default:
  9544  			cc.logf("Transport: unhandled response frame type %T", f)
  9545  		}
  9546  		if err != nil {
  9547  			if http2VerboseLogs {
  9548  				cc.vlogf("http2: Transport conn %p received error from processing frame %v: %v", cc, http2summarizeFrame(f), err)
  9549  			}
  9550  			return err
  9551  		}
  9552  	}
  9553  }
  9554  
  9555  func (rl *http2clientConnReadLoop) processHeaders(f *http2MetaHeadersFrame) error {
  9556  	cs := rl.streamByID(f.StreamID)
  9557  	if cs == nil {
  9558  		// We'd get here if we canceled a request while the
  9559  		// server had its response still in flight. So if this
  9560  		// was just something we canceled, ignore it.
  9561  		return nil
  9562  	}
  9563  	if cs.readClosed {
  9564  		rl.endStreamError(cs, http2StreamError{
  9565  			StreamID: f.StreamID,
  9566  			Code:     http2ErrCodeProtocol,
  9567  			Cause:    errors.New("protocol error: headers after END_STREAM"),
  9568  		})
  9569  		return nil
  9570  	}
  9571  	if !cs.firstByte {
  9572  		if cs.trace != nil {
  9573  			// TODO(bradfitz): move first response byte earlier,
  9574  			// when we first read the 9 byte header, not waiting
  9575  			// until all the HEADERS+CONTINUATION frames have been
  9576  			// merged. This works for now.
  9577  			http2traceFirstResponseByte(cs.trace)
  9578  		}
  9579  		cs.firstByte = true
  9580  	}
  9581  	if !cs.pastHeaders {
  9582  		cs.pastHeaders = true
  9583  	} else {
  9584  		return rl.processTrailers(cs, f)
  9585  	}
  9586  
  9587  	res, err := rl.handleResponse(cs, f)
  9588  	if err != nil {
  9589  		if _, ok := err.(http2ConnectionError); ok {
  9590  			return err
  9591  		}
  9592  		// Any other error type is a stream error.
  9593  		rl.endStreamError(cs, http2StreamError{
  9594  			StreamID: f.StreamID,
  9595  			Code:     http2ErrCodeProtocol,
  9596  			Cause:    err,
  9597  		})
  9598  		return nil // return nil from process* funcs to keep conn alive
  9599  	}
  9600  	if res == nil {
  9601  		// (nil, nil) special case. See handleResponse docs.
  9602  		return nil
  9603  	}
  9604  	cs.resTrailer = &res.Trailer
  9605  	cs.res = res
  9606  	close(cs.respHeaderRecv)
  9607  	if f.StreamEnded() {
  9608  		rl.endStream(cs)
  9609  	}
  9610  	return nil
  9611  }
  9612  
  9613  // may return error types nil, or ConnectionError. Any other error value
  9614  // is a StreamError of type ErrCodeProtocol. The returned error in that case
  9615  // is the detail.
  9616  //
  9617  // As a special case, handleResponse may return (nil, nil) to skip the
  9618  // frame (currently only used for 1xx responses).
  9619  func (rl *http2clientConnReadLoop) handleResponse(cs *http2clientStream, f *http2MetaHeadersFrame) (*Response, error) {
  9620  	if f.Truncated {
  9621  		return nil, http2errResponseHeaderListSize
  9622  	}
  9623  
  9624  	status := f.PseudoValue("status")
  9625  	if status == "" {
  9626  		return nil, errors.New("malformed response from server: missing status pseudo header")
  9627  	}
  9628  	statusCode, err := strconv.Atoi(status)
  9629  	if err != nil {
  9630  		return nil, errors.New("malformed response from server: malformed non-numeric status pseudo header")
  9631  	}
  9632  
  9633  	regularFields := f.RegularFields()
  9634  	strs := make([]string, len(regularFields))
  9635  	header := make(Header, len(regularFields))
  9636  	res := &Response{
  9637  		Proto:      "HTTP/2.0",
  9638  		ProtoMajor: 2,
  9639  		Header:     header,
  9640  		StatusCode: statusCode,
  9641  		Status:     status + " " + StatusText(statusCode),
  9642  	}
  9643  	for _, hf := range regularFields {
  9644  		key := http2canonicalHeader(hf.Name)
  9645  		if key == "Trailer" {
  9646  			t := res.Trailer
  9647  			if t == nil {
  9648  				t = make(Header)
  9649  				res.Trailer = t
  9650  			}
  9651  			http2foreachHeaderElement(hf.Value, func(v string) {
  9652  				t[http2canonicalHeader(v)] = nil
  9653  			})
  9654  		} else {
  9655  			vv := header[key]
  9656  			if vv == nil && len(strs) > 0 {
  9657  				// More than likely this will be a single-element key.
  9658  				// Most headers aren't multi-valued.
  9659  				// Set the capacity on strs[0] to 1, so any future append
  9660  				// won't extend the slice into the other strings.
  9661  				vv, strs = strs[:1:1], strs[1:]
  9662  				vv[0] = hf.Value
  9663  				header[key] = vv
  9664  			} else {
  9665  				header[key] = append(vv, hf.Value)
  9666  			}
  9667  		}
  9668  	}
  9669  
  9670  	if statusCode >= 100 && statusCode <= 199 {
  9671  		if f.StreamEnded() {
  9672  			return nil, errors.New("1xx informational response with END_STREAM flag")
  9673  		}
  9674  		cs.num1xx++
  9675  		const max1xxResponses = 5 // arbitrary bound on number of informational responses, same as net/http
  9676  		if cs.num1xx > max1xxResponses {
  9677  			return nil, errors.New("http2: too many 1xx informational responses")
  9678  		}
  9679  		if fn := cs.get1xxTraceFunc(); fn != nil {
  9680  			if err := fn(statusCode, textproto.MIMEHeader(header)); err != nil {
  9681  				return nil, err
  9682  			}
  9683  		}
  9684  		if statusCode == 100 {
  9685  			http2traceGot100Continue(cs.trace)
  9686  			select {
  9687  			case cs.on100 <- struct{}{}:
  9688  			default:
  9689  			}
  9690  		}
  9691  		cs.pastHeaders = false // do it all again
  9692  		return nil, nil
  9693  	}
  9694  
  9695  	res.ContentLength = -1
  9696  	if clens := res.Header["Content-Length"]; len(clens) == 1 {
  9697  		if cl, err := strconv.ParseUint(clens[0], 10, 63); err == nil {
  9698  			res.ContentLength = int64(cl)
  9699  		} else {
  9700  			// TODO: care? unlike http/1, it won't mess up our framing, so it's
  9701  			// more safe smuggling-wise to ignore.
  9702  		}
  9703  	} else if len(clens) > 1 {
  9704  		// TODO: care? unlike http/1, it won't mess up our framing, so it's
  9705  		// more safe smuggling-wise to ignore.
  9706  	} else if f.StreamEnded() && !cs.isHead {
  9707  		res.ContentLength = 0
  9708  	}
  9709  
  9710  	if cs.isHead {
  9711  		res.Body = http2noBody
  9712  		return res, nil
  9713  	}
  9714  
  9715  	if f.StreamEnded() {
  9716  		if res.ContentLength > 0 {
  9717  			res.Body = http2missingBody{}
  9718  		} else {
  9719  			res.Body = http2noBody
  9720  		}
  9721  		return res, nil
  9722  	}
  9723  
  9724  	cs.bufPipe.setBuffer(&http2dataBuffer{expected: res.ContentLength})
  9725  	cs.bytesRemain = res.ContentLength
  9726  	res.Body = http2transportResponseBody{cs}
  9727  
  9728  	if cs.requestedGzip && http2asciiEqualFold(res.Header.Get("Content-Encoding"), "gzip") {
  9729  		res.Header.Del("Content-Encoding")
  9730  		res.Header.Del("Content-Length")
  9731  		res.ContentLength = -1
  9732  		res.Body = &http2gzipReader{body: res.Body}
  9733  		res.Uncompressed = true
  9734  	}
  9735  	return res, nil
  9736  }
  9737  
  9738  func (rl *http2clientConnReadLoop) processTrailers(cs *http2clientStream, f *http2MetaHeadersFrame) error {
  9739  	if cs.pastTrailers {
  9740  		// Too many HEADERS frames for this stream.
  9741  		return http2ConnectionError(http2ErrCodeProtocol)
  9742  	}
  9743  	cs.pastTrailers = true
  9744  	if !f.StreamEnded() {
  9745  		// We expect that any headers for trailers also
  9746  		// has END_STREAM.
  9747  		return http2ConnectionError(http2ErrCodeProtocol)
  9748  	}
  9749  	if len(f.PseudoFields()) > 0 {
  9750  		// No pseudo header fields are defined for trailers.
  9751  		// TODO: ConnectionError might be overly harsh? Check.
  9752  		return http2ConnectionError(http2ErrCodeProtocol)
  9753  	}
  9754  
  9755  	trailer := make(Header)
  9756  	for _, hf := range f.RegularFields() {
  9757  		key := http2canonicalHeader(hf.Name)
  9758  		trailer[key] = append(trailer[key], hf.Value)
  9759  	}
  9760  	cs.trailer = trailer
  9761  
  9762  	rl.endStream(cs)
  9763  	return nil
  9764  }
  9765  
  9766  // transportResponseBody is the concrete type of Transport.RoundTrip's
  9767  // Response.Body. It is an io.ReadCloser.
  9768  type http2transportResponseBody struct {
  9769  	cs *http2clientStream
  9770  }
  9771  
  9772  func (b http2transportResponseBody) Read(p []byte) (n int, err error) {
  9773  	cs := b.cs
  9774  	cc := cs.cc
  9775  
  9776  	if cs.readErr != nil {
  9777  		return 0, cs.readErr
  9778  	}
  9779  	n, err = b.cs.bufPipe.Read(p)
  9780  	if cs.bytesRemain != -1 {
  9781  		if int64(n) > cs.bytesRemain {
  9782  			n = int(cs.bytesRemain)
  9783  			if err == nil {
  9784  				err = errors.New("net/http: server replied with more than declared Content-Length; truncated")
  9785  				cs.abortStream(err)
  9786  			}
  9787  			cs.readErr = err
  9788  			return int(cs.bytesRemain), err
  9789  		}
  9790  		cs.bytesRemain -= int64(n)
  9791  		if err == io.EOF && cs.bytesRemain > 0 {
  9792  			err = io.ErrUnexpectedEOF
  9793  			cs.readErr = err
  9794  			return n, err
  9795  		}
  9796  	}
  9797  	if n == 0 {
  9798  		// No flow control tokens to send back.
  9799  		return
  9800  	}
  9801  
  9802  	cc.mu.Lock()
  9803  	connAdd := cc.inflow.add(n)
  9804  	var streamAdd int32
  9805  	if err == nil { // No need to refresh if the stream is over or failed.
  9806  		streamAdd = cs.inflow.add(n)
  9807  	}
  9808  	cc.mu.Unlock()
  9809  
  9810  	if connAdd != 0 || streamAdd != 0 {
  9811  		cc.wmu.Lock()
  9812  		defer cc.wmu.Unlock()
  9813  		if connAdd != 0 {
  9814  			cc.fr.WriteWindowUpdate(0, http2mustUint31(connAdd))
  9815  		}
  9816  		if streamAdd != 0 {
  9817  			cc.fr.WriteWindowUpdate(cs.ID, http2mustUint31(streamAdd))
  9818  		}
  9819  		cc.bw.Flush()
  9820  	}
  9821  	return
  9822  }
  9823  
  9824  var http2errClosedResponseBody = errors.New("http2: response body closed")
  9825  
  9826  func (b http2transportResponseBody) Close() error {
  9827  	cs := b.cs
  9828  	cc := cs.cc
  9829  
  9830  	cs.bufPipe.BreakWithError(http2errClosedResponseBody)
  9831  	cs.abortStream(http2errClosedResponseBody)
  9832  
  9833  	unread := cs.bufPipe.Len()
  9834  	if unread > 0 {
  9835  		cc.mu.Lock()
  9836  		// Return connection-level flow control.
  9837  		connAdd := cc.inflow.add(unread)
  9838  		cc.mu.Unlock()
  9839  
  9840  		// TODO(dneil): Acquiring this mutex can block indefinitely.
  9841  		// Move flow control return to a goroutine?
  9842  		cc.wmu.Lock()
  9843  		// Return connection-level flow control.
  9844  		if connAdd > 0 {
  9845  			cc.fr.WriteWindowUpdate(0, uint32(connAdd))
  9846  		}
  9847  		cc.bw.Flush()
  9848  		cc.wmu.Unlock()
  9849  	}
  9850  
  9851  	select {
  9852  	case <-cs.donec:
  9853  	case <-cs.ctx.Done():
  9854  		// See golang/go#49366: The net/http package can cancel the
  9855  		// request context after the response body is fully read.
  9856  		// Don't treat this as an error.
  9857  		return nil
  9858  	case <-cs.reqCancel:
  9859  		return http2errRequestCanceled
  9860  	}
  9861  	return nil
  9862  }
  9863  
  9864  func (rl *http2clientConnReadLoop) processData(f *http2DataFrame) error {
  9865  	cc := rl.cc
  9866  	cs := rl.streamByID(f.StreamID)
  9867  	data := f.Data()
  9868  	if cs == nil {
  9869  		cc.mu.Lock()
  9870  		neverSent := cc.nextStreamID
  9871  		cc.mu.Unlock()
  9872  		if f.StreamID >= neverSent {
  9873  			// We never asked for this.
  9874  			cc.logf("http2: Transport received unsolicited DATA frame; closing connection")
  9875  			return http2ConnectionError(http2ErrCodeProtocol)
  9876  		}
  9877  		// We probably did ask for this, but canceled. Just ignore it.
  9878  		// TODO: be stricter here? only silently ignore things which
  9879  		// we canceled, but not things which were closed normally
  9880  		// by the peer? Tough without accumulating too much state.
  9881  
  9882  		// But at least return their flow control:
  9883  		if f.Length > 0 {
  9884  			cc.mu.Lock()
  9885  			ok := cc.inflow.take(f.Length)
  9886  			connAdd := cc.inflow.add(int(f.Length))
  9887  			cc.mu.Unlock()
  9888  			if !ok {
  9889  				return http2ConnectionError(http2ErrCodeFlowControl)
  9890  			}
  9891  			if connAdd > 0 {
  9892  				cc.wmu.Lock()
  9893  				cc.fr.WriteWindowUpdate(0, uint32(connAdd))
  9894  				cc.bw.Flush()
  9895  				cc.wmu.Unlock()
  9896  			}
  9897  		}
  9898  		return nil
  9899  	}
  9900  	if cs.readClosed {
  9901  		cc.logf("protocol error: received DATA after END_STREAM")
  9902  		rl.endStreamError(cs, http2StreamError{
  9903  			StreamID: f.StreamID,
  9904  			Code:     http2ErrCodeProtocol,
  9905  		})
  9906  		return nil
  9907  	}
  9908  	if !cs.pastHeaders {
  9909  		cc.logf("protocol error: received DATA before a HEADERS frame")
  9910  		rl.endStreamError(cs, http2StreamError{
  9911  			StreamID: f.StreamID,
  9912  			Code:     http2ErrCodeProtocol,
  9913  		})
  9914  		return nil
  9915  	}
  9916  	if f.Length > 0 {
  9917  		if cs.isHead && len(data) > 0 {
  9918  			cc.logf("protocol error: received DATA on a HEAD request")
  9919  			rl.endStreamError(cs, http2StreamError{
  9920  				StreamID: f.StreamID,
  9921  				Code:     http2ErrCodeProtocol,
  9922  			})
  9923  			return nil
  9924  		}
  9925  		// Check connection-level flow control.
  9926  		cc.mu.Lock()
  9927  		if !http2takeInflows(&cc.inflow, &cs.inflow, f.Length) {
  9928  			cc.mu.Unlock()
  9929  			return http2ConnectionError(http2ErrCodeFlowControl)
  9930  		}
  9931  		// Return any padded flow control now, since we won't
  9932  		// refund it later on body reads.
  9933  		var refund int
  9934  		if pad := int(f.Length) - len(data); pad > 0 {
  9935  			refund += pad
  9936  		}
  9937  
  9938  		didReset := false
  9939  		var err error
  9940  		if len(data) > 0 {
  9941  			if _, err = cs.bufPipe.Write(data); err != nil {
  9942  				// Return len(data) now if the stream is already closed,
  9943  				// since data will never be read.
  9944  				didReset = true
  9945  				refund += len(data)
  9946  			}
  9947  		}
  9948  
  9949  		sendConn := cc.inflow.add(refund)
  9950  		var sendStream int32
  9951  		if !didReset {
  9952  			sendStream = cs.inflow.add(refund)
  9953  		}
  9954  		cc.mu.Unlock()
  9955  
  9956  		if sendConn > 0 || sendStream > 0 {
  9957  			cc.wmu.Lock()
  9958  			if sendConn > 0 {
  9959  				cc.fr.WriteWindowUpdate(0, uint32(sendConn))
  9960  			}
  9961  			if sendStream > 0 {
  9962  				cc.fr.WriteWindowUpdate(cs.ID, uint32(sendStream))
  9963  			}
  9964  			cc.bw.Flush()
  9965  			cc.wmu.Unlock()
  9966  		}
  9967  
  9968  		if err != nil {
  9969  			rl.endStreamError(cs, err)
  9970  			return nil
  9971  		}
  9972  	}
  9973  
  9974  	if f.StreamEnded() {
  9975  		rl.endStream(cs)
  9976  	}
  9977  	return nil
  9978  }
  9979  
  9980  func (rl *http2clientConnReadLoop) endStream(cs *http2clientStream) {
  9981  	// TODO: check that any declared content-length matches, like
  9982  	// server.go's (*stream).endStream method.
  9983  	if !cs.readClosed {
  9984  		cs.readClosed = true
  9985  		// Close cs.bufPipe and cs.peerClosed with cc.mu held to avoid a
  9986  		// race condition: The caller can read io.EOF from Response.Body
  9987  		// and close the body before we close cs.peerClosed, causing
  9988  		// cleanupWriteRequest to send a RST_STREAM.
  9989  		rl.cc.mu.Lock()
  9990  		defer rl.cc.mu.Unlock()
  9991  		cs.bufPipe.closeWithErrorAndCode(io.EOF, cs.copyTrailers)
  9992  		close(cs.peerClosed)
  9993  	}
  9994  }
  9995  
  9996  func (rl *http2clientConnReadLoop) endStreamError(cs *http2clientStream, err error) {
  9997  	cs.readAborted = true
  9998  	cs.abortStream(err)
  9999  }
 10000  
 10001  func (rl *http2clientConnReadLoop) streamByID(id uint32) *http2clientStream {
 10002  	rl.cc.mu.Lock()
 10003  	defer rl.cc.mu.Unlock()
 10004  	cs := rl.cc.streams[id]
 10005  	if cs != nil && !cs.readAborted {
 10006  		return cs
 10007  	}
 10008  	return nil
 10009  }
 10010  
 10011  func (cs *http2clientStream) copyTrailers() {
 10012  	for k, vv := range cs.trailer {
 10013  		t := cs.resTrailer
 10014  		if *t == nil {
 10015  			*t = make(Header)
 10016  		}
 10017  		(*t)[k] = vv
 10018  	}
 10019  }
 10020  
 10021  func (rl *http2clientConnReadLoop) processGoAway(f *http2GoAwayFrame) error {
 10022  	cc := rl.cc
 10023  	cc.t.connPool().MarkDead(cc)
 10024  	if f.ErrCode != 0 {
 10025  		// TODO: deal with GOAWAY more. particularly the error code
 10026  		cc.vlogf("transport got GOAWAY with error code = %v", f.ErrCode)
 10027  		if fn := cc.t.CountError; fn != nil {
 10028  			fn("recv_goaway_" + f.ErrCode.stringToken())
 10029  		}
 10030  	}
 10031  	cc.setGoAway(f)
 10032  	return nil
 10033  }
 10034  
 10035  func (rl *http2clientConnReadLoop) processSettings(f *http2SettingsFrame) error {
 10036  	cc := rl.cc
 10037  	// Locking both mu and wmu here allows frame encoding to read settings with only wmu held.
 10038  	// Acquiring wmu when f.IsAck() is unnecessary, but convenient and mostly harmless.
 10039  	cc.wmu.Lock()
 10040  	defer cc.wmu.Unlock()
 10041  
 10042  	if err := rl.processSettingsNoWrite(f); err != nil {
 10043  		return err
 10044  	}
 10045  	if !f.IsAck() {
 10046  		cc.fr.WriteSettingsAck()
 10047  		cc.bw.Flush()
 10048  	}
 10049  	return nil
 10050  }
 10051  
 10052  func (rl *http2clientConnReadLoop) processSettingsNoWrite(f *http2SettingsFrame) error {
 10053  	cc := rl.cc
 10054  	cc.mu.Lock()
 10055  	defer cc.mu.Unlock()
 10056  
 10057  	if f.IsAck() {
 10058  		if cc.wantSettingsAck {
 10059  			cc.wantSettingsAck = false
 10060  			return nil
 10061  		}
 10062  		return http2ConnectionError(http2ErrCodeProtocol)
 10063  	}
 10064  
 10065  	var seenMaxConcurrentStreams bool
 10066  	err := f.ForeachSetting(func(s http2Setting) error {
 10067  		switch s.ID {
 10068  		case http2SettingMaxFrameSize:
 10069  			cc.maxFrameSize = s.Val
 10070  		case http2SettingMaxConcurrentStreams:
 10071  			cc.maxConcurrentStreams = s.Val
 10072  			seenMaxConcurrentStreams = true
 10073  		case http2SettingMaxHeaderListSize:
 10074  			cc.peerMaxHeaderListSize = uint64(s.Val)
 10075  		case http2SettingInitialWindowSize:
 10076  			// Values above the maximum flow-control
 10077  			// window size of 2^31-1 MUST be treated as a
 10078  			// connection error (Section 5.4.1) of type
 10079  			// FLOW_CONTROL_ERROR.
 10080  			if s.Val > math.MaxInt32 {
 10081  				return http2ConnectionError(http2ErrCodeFlowControl)
 10082  			}
 10083  
 10084  			// Adjust flow control of currently-open
 10085  			// frames by the difference of the old initial
 10086  			// window size and this one.
 10087  			delta := int32(s.Val) - int32(cc.initialWindowSize)
 10088  			for _, cs := range cc.streams {
 10089  				cs.flow.add(delta)
 10090  			}
 10091  			cc.cond.Broadcast()
 10092  
 10093  			cc.initialWindowSize = s.Val
 10094  		case http2SettingHeaderTableSize:
 10095  			cc.henc.SetMaxDynamicTableSize(s.Val)
 10096  			cc.peerMaxHeaderTableSize = s.Val
 10097  		default:
 10098  			cc.vlogf("Unhandled Setting: %v", s)
 10099  		}
 10100  		return nil
 10101  	})
 10102  	if err != nil {
 10103  		return err
 10104  	}
 10105  
 10106  	if !cc.seenSettings {
 10107  		if !seenMaxConcurrentStreams {
 10108  			// This was the servers initial SETTINGS frame and it
 10109  			// didn't contain a MAX_CONCURRENT_STREAMS field so
 10110  			// increase the number of concurrent streams this
 10111  			// connection can establish to our default.
 10112  			cc.maxConcurrentStreams = http2defaultMaxConcurrentStreams
 10113  		}
 10114  		cc.seenSettings = true
 10115  	}
 10116  
 10117  	return nil
 10118  }
 10119  
 10120  func (rl *http2clientConnReadLoop) processWindowUpdate(f *http2WindowUpdateFrame) error {
 10121  	cc := rl.cc
 10122  	cs := rl.streamByID(f.StreamID)
 10123  	if f.StreamID != 0 && cs == nil {
 10124  		return nil
 10125  	}
 10126  
 10127  	cc.mu.Lock()
 10128  	defer cc.mu.Unlock()
 10129  
 10130  	fl := &cc.flow
 10131  	if cs != nil {
 10132  		fl = &cs.flow
 10133  	}
 10134  	if !fl.add(int32(f.Increment)) {
 10135  		// For stream, the sender sends RST_STREAM with an error code of FLOW_CONTROL_ERROR
 10136  		if cs != nil {
 10137  			rl.endStreamError(cs, http2StreamError{
 10138  				StreamID: f.StreamID,
 10139  				Code:     http2ErrCodeFlowControl,
 10140  			})
 10141  			return nil
 10142  		}
 10143  
 10144  		return http2ConnectionError(http2ErrCodeFlowControl)
 10145  	}
 10146  	cc.cond.Broadcast()
 10147  	return nil
 10148  }
 10149  
 10150  func (rl *http2clientConnReadLoop) processResetStream(f *http2RSTStreamFrame) error {
 10151  	cs := rl.streamByID(f.StreamID)
 10152  	if cs == nil {
 10153  		// TODO: return error if server tries to RST_STREAM an idle stream
 10154  		return nil
 10155  	}
 10156  	serr := http2streamError(cs.ID, f.ErrCode)
 10157  	serr.Cause = http2errFromPeer
 10158  	if f.ErrCode == http2ErrCodeProtocol {
 10159  		rl.cc.SetDoNotReuse()
 10160  	}
 10161  	if fn := cs.cc.t.CountError; fn != nil {
 10162  		fn("recv_rststream_" + f.ErrCode.stringToken())
 10163  	}
 10164  	cs.abortStream(serr)
 10165  
 10166  	cs.bufPipe.CloseWithError(serr)
 10167  	return nil
 10168  }
 10169  
 10170  // Ping sends a PING frame to the server and waits for the ack.
 10171  func (cc *http2ClientConn) Ping(ctx context.Context) error {
 10172  	c := make(chan struct{})
 10173  	// Generate a random payload
 10174  	var p [8]byte
 10175  	for {
 10176  		if _, err := rand.Read(p[:]); err != nil {
 10177  			return err
 10178  		}
 10179  		cc.mu.Lock()
 10180  		// check for dup before insert
 10181  		if _, found := cc.pings[p]; !found {
 10182  			cc.pings[p] = c
 10183  			cc.mu.Unlock()
 10184  			break
 10185  		}
 10186  		cc.mu.Unlock()
 10187  	}
 10188  	var pingError error
 10189  	errc := make(chan struct{})
 10190  	go func() {
 10191  		cc.t.markNewGoroutine()
 10192  		cc.wmu.Lock()
 10193  		defer cc.wmu.Unlock()
 10194  		if pingError = cc.fr.WritePing(false, p); pingError != nil {
 10195  			close(errc)
 10196  			return
 10197  		}
 10198  		if pingError = cc.bw.Flush(); pingError != nil {
 10199  			close(errc)
 10200  			return
 10201  		}
 10202  	}()
 10203  	select {
 10204  	case <-c:
 10205  		return nil
 10206  	case <-errc:
 10207  		return pingError
 10208  	case <-ctx.Done():
 10209  		return ctx.Err()
 10210  	case <-cc.readerDone:
 10211  		// connection closed
 10212  		return cc.readerErr
 10213  	}
 10214  }
 10215  
 10216  func (rl *http2clientConnReadLoop) processPing(f *http2PingFrame) error {
 10217  	if f.IsAck() {
 10218  		cc := rl.cc
 10219  		cc.mu.Lock()
 10220  		defer cc.mu.Unlock()
 10221  		// If ack, notify listener if any
 10222  		if c, ok := cc.pings[f.Data]; ok {
 10223  			close(c)
 10224  			delete(cc.pings, f.Data)
 10225  		}
 10226  		return nil
 10227  	}
 10228  	cc := rl.cc
 10229  	cc.wmu.Lock()
 10230  	defer cc.wmu.Unlock()
 10231  	if err := cc.fr.WritePing(true, f.Data); err != nil {
 10232  		return err
 10233  	}
 10234  	return cc.bw.Flush()
 10235  }
 10236  
 10237  func (rl *http2clientConnReadLoop) processPushPromise(f *http2PushPromiseFrame) error {
 10238  	// We told the peer we don't want them.
 10239  	// Spec says:
 10240  	// "PUSH_PROMISE MUST NOT be sent if the SETTINGS_ENABLE_PUSH
 10241  	// setting of the peer endpoint is set to 0. An endpoint that
 10242  	// has set this setting and has received acknowledgement MUST
 10243  	// treat the receipt of a PUSH_PROMISE frame as a connection
 10244  	// error (Section 5.4.1) of type PROTOCOL_ERROR."
 10245  	return http2ConnectionError(http2ErrCodeProtocol)
 10246  }
 10247  
 10248  func (cc *http2ClientConn) writeStreamReset(streamID uint32, code http2ErrCode, err error) {
 10249  	// TODO: map err to more interesting error codes, once the
 10250  	// HTTP community comes up with some. But currently for
 10251  	// RST_STREAM there's no equivalent to GOAWAY frame's debug
 10252  	// data, and the error codes are all pretty vague ("cancel").
 10253  	cc.wmu.Lock()
 10254  	cc.fr.WriteRSTStream(streamID, code)
 10255  	cc.bw.Flush()
 10256  	cc.wmu.Unlock()
 10257  }
 10258  
 10259  var (
 10260  	http2errResponseHeaderListSize = errors.New("http2: response header list larger than advertised limit")
 10261  	http2errRequestHeaderListSize  = errors.New("http2: request header list larger than peer's advertised limit")
 10262  )
 10263  
 10264  func (cc *http2ClientConn) logf(format string, args ...interface{}) {
 10265  	cc.t.logf(format, args...)
 10266  }
 10267  
 10268  func (cc *http2ClientConn) vlogf(format string, args ...interface{}) {
 10269  	cc.t.vlogf(format, args...)
 10270  }
 10271  
 10272  func (t *http2Transport) vlogf(format string, args ...interface{}) {
 10273  	if http2VerboseLogs {
 10274  		t.logf(format, args...)
 10275  	}
 10276  }
 10277  
 10278  func (t *http2Transport) logf(format string, args ...interface{}) {
 10279  	log.Printf(format, args...)
 10280  }
 10281  
 10282  var http2noBody io.ReadCloser = http2noBodyReader{}
 10283  
 10284  type http2noBodyReader struct{}
 10285  
 10286  func (http2noBodyReader) Close() error { return nil }
 10287  
 10288  func (http2noBodyReader) Read([]byte) (int, error) { return 0, io.EOF }
 10289  
 10290  type http2missingBody struct{}
 10291  
 10292  func (http2missingBody) Close() error { return nil }
 10293  
 10294  func (http2missingBody) Read([]byte) (int, error) { return 0, io.ErrUnexpectedEOF }
 10295  
 10296  func http2strSliceContains(ss []string, s string) bool {
 10297  	for _, v := range ss {
 10298  		if v == s {
 10299  			return true
 10300  		}
 10301  	}
 10302  	return false
 10303  }
 10304  
 10305  type http2erringRoundTripper struct{ err error }
 10306  
 10307  func (rt http2erringRoundTripper) RoundTripErr() error { return rt.err }
 10308  
 10309  func (rt http2erringRoundTripper) RoundTrip(*Request) (*Response, error) { return nil, rt.err }
 10310  
 10311  // gzipReader wraps a response body so it can lazily
 10312  // call gzip.NewReader on the first call to Read
 10313  type http2gzipReader struct {
 10314  	_    http2incomparable
 10315  	body io.ReadCloser // underlying Response.Body
 10316  	zr   *gzip.Reader  // lazily-initialized gzip reader
 10317  	zerr error         // sticky error
 10318  }
 10319  
 10320  func (gz *http2gzipReader) Read(p []byte) (n int, err error) {
 10321  	if gz.zerr != nil {
 10322  		return 0, gz.zerr
 10323  	}
 10324  	if gz.zr == nil {
 10325  		gz.zr, err = gzip.NewReader(gz.body)
 10326  		if err != nil {
 10327  			gz.zerr = err
 10328  			return 0, err
 10329  		}
 10330  	}
 10331  	return gz.zr.Read(p)
 10332  }
 10333  
 10334  func (gz *http2gzipReader) Close() error {
 10335  	if err := gz.body.Close(); err != nil {
 10336  		return err
 10337  	}
 10338  	gz.zerr = fs.ErrClosed
 10339  	return nil
 10340  }
 10341  
 10342  type http2errorReader struct{ err error }
 10343  
 10344  func (r http2errorReader) Read(p []byte) (int, error) { return 0, r.err }
 10345  
 10346  // isConnectionCloseRequest reports whether req should use its own
 10347  // connection for a single request and then close the connection.
 10348  func http2isConnectionCloseRequest(req *Request) bool {
 10349  	return req.Close || httpguts.HeaderValuesContainsToken(req.Header["Connection"], "close")
 10350  }
 10351  
 10352  // registerHTTPSProtocol calls Transport.RegisterProtocol but
 10353  // converting panics into errors.
 10354  func http2registerHTTPSProtocol(t *Transport, rt http2noDialH2RoundTripper) (err error) {
 10355  	defer func() {
 10356  		if e := recover(); e != nil {
 10357  			err = fmt.Errorf("%v", e)
 10358  		}
 10359  	}()
 10360  	t.RegisterProtocol("https", rt)
 10361  	return nil
 10362  }
 10363  
 10364  // noDialH2RoundTripper is a RoundTripper which only tries to complete the request
 10365  // if there's already has a cached connection to the host.
 10366  // (The field is exported so it can be accessed via reflect from net/http; tested
 10367  // by TestNoDialH2RoundTripperType)
 10368  type http2noDialH2RoundTripper struct{ *http2Transport }
 10369  
 10370  func (rt http2noDialH2RoundTripper) RoundTrip(req *Request) (*Response, error) {
 10371  	res, err := rt.http2Transport.RoundTrip(req)
 10372  	if http2isNoCachedConnError(err) {
 10373  		return nil, ErrSkipAltProtocol
 10374  	}
 10375  	return res, err
 10376  }
 10377  
 10378  func (t *http2Transport) idleConnTimeout() time.Duration {
 10379  	// to keep things backwards compatible, we use non-zero values of
 10380  	// IdleConnTimeout, followed by using the IdleConnTimeout on the underlying
 10381  	// http1 transport, followed by 0
 10382  	if t.IdleConnTimeout != 0 {
 10383  		return t.IdleConnTimeout
 10384  	}
 10385  
 10386  	if t.t1 != nil {
 10387  		return t.t1.IdleConnTimeout
 10388  	}
 10389  
 10390  	return 0
 10391  }
 10392  
 10393  func http2traceGetConn(req *Request, hostPort string) {
 10394  	trace := httptrace.ContextClientTrace(req.Context())
 10395  	if trace == nil || trace.GetConn == nil {
 10396  		return
 10397  	}
 10398  	trace.GetConn(hostPort)
 10399  }
 10400  
 10401  func http2traceGotConn(req *Request, cc *http2ClientConn, reused bool) {
 10402  	trace := httptrace.ContextClientTrace(req.Context())
 10403  	if trace == nil || trace.GotConn == nil {
 10404  		return
 10405  	}
 10406  	ci := httptrace.GotConnInfo{Conn: cc.tconn}
 10407  	ci.Reused = reused
 10408  	cc.mu.Lock()
 10409  	ci.WasIdle = len(cc.streams) == 0 && reused
 10410  	if ci.WasIdle && !cc.lastActive.IsZero() {
 10411  		ci.IdleTime = time.Since(cc.lastActive)
 10412  	}
 10413  	cc.mu.Unlock()
 10414  
 10415  	trace.GotConn(ci)
 10416  }
 10417  
 10418  func http2traceWroteHeaders(trace *httptrace.ClientTrace) {
 10419  	if trace != nil && trace.WroteHeaders != nil {
 10420  		trace.WroteHeaders()
 10421  	}
 10422  }
 10423  
 10424  func http2traceGot100Continue(trace *httptrace.ClientTrace) {
 10425  	if trace != nil && trace.Got100Continue != nil {
 10426  		trace.Got100Continue()
 10427  	}
 10428  }
 10429  
 10430  func http2traceWait100Continue(trace *httptrace.ClientTrace) {
 10431  	if trace != nil && trace.Wait100Continue != nil {
 10432  		trace.Wait100Continue()
 10433  	}
 10434  }
 10435  
 10436  func http2traceWroteRequest(trace *httptrace.ClientTrace, err error) {
 10437  	if trace != nil && trace.WroteRequest != nil {
 10438  		trace.WroteRequest(httptrace.WroteRequestInfo{Err: err})
 10439  	}
 10440  }
 10441  
 10442  func http2traceFirstResponseByte(trace *httptrace.ClientTrace) {
 10443  	if trace != nil && trace.GotFirstResponseByte != nil {
 10444  		trace.GotFirstResponseByte()
 10445  	}
 10446  }
 10447  
 10448  func http2traceHasWroteHeaderField(trace *httptrace.ClientTrace) bool {
 10449  	return trace != nil && trace.WroteHeaderField != nil
 10450  }
 10451  
 10452  func http2traceWroteHeaderField(trace *httptrace.ClientTrace, k, v string) {
 10453  	if trace != nil && trace.WroteHeaderField != nil {
 10454  		trace.WroteHeaderField(k, []string{v})
 10455  	}
 10456  }
 10457  
 10458  func http2traceGot1xxResponseFunc(trace *httptrace.ClientTrace) func(int, textproto.MIMEHeader) error {
 10459  	if trace != nil {
 10460  		return trace.Got1xxResponse
 10461  	}
 10462  	return nil
 10463  }
 10464  
 10465  // dialTLSWithContext uses tls.Dialer, added in Go 1.15, to open a TLS
 10466  // connection.
 10467  func (t *http2Transport) dialTLSWithContext(ctx context.Context, network, addr string, cfg *tls.Config) (*tls.Conn, error) {
 10468  	dialer := &tls.Dialer{
 10469  		Config: cfg,
 10470  	}
 10471  	cn, err := dialer.DialContext(ctx, network, addr)
 10472  	if err != nil {
 10473  		return nil, err
 10474  	}
 10475  	tlsCn := cn.(*tls.Conn) // DialContext comment promises this will always succeed
 10476  	return tlsCn, nil
 10477  }
 10478  
 10479  // writeFramer is implemented by any type that is used to write frames.
 10480  type http2writeFramer interface {
 10481  	writeFrame(http2writeContext) error
 10482  
 10483  	// staysWithinBuffer reports whether this writer promises that
 10484  	// it will only write less than or equal to size bytes, and it
 10485  	// won't Flush the write context.
 10486  	staysWithinBuffer(size int) bool
 10487  }
 10488  
 10489  // writeContext is the interface needed by the various frame writer
 10490  // types below. All the writeFrame methods below are scheduled via the
 10491  // frame writing scheduler (see writeScheduler in writesched.go).
 10492  //
 10493  // This interface is implemented by *serverConn.
 10494  //
 10495  // TODO: decide whether to a) use this in the client code (which didn't
 10496  // end up using this yet, because it has a simpler design, not
 10497  // currently implementing priorities), or b) delete this and
 10498  // make the server code a bit more concrete.
 10499  type http2writeContext interface {
 10500  	Framer() *http2Framer
 10501  	Flush() error
 10502  	CloseConn() error
 10503  	// HeaderEncoder returns an HPACK encoder that writes to the
 10504  	// returned buffer.
 10505  	HeaderEncoder() (*hpack.Encoder, *bytes.Buffer)
 10506  }
 10507  
 10508  // writeEndsStream reports whether w writes a frame that will transition
 10509  // the stream to a half-closed local state. This returns false for RST_STREAM,
 10510  // which closes the entire stream (not just the local half).
 10511  func http2writeEndsStream(w http2writeFramer) bool {
 10512  	switch v := w.(type) {
 10513  	case *http2writeData:
 10514  		return v.endStream
 10515  	case *http2writeResHeaders:
 10516  		return v.endStream
 10517  	case nil:
 10518  		// This can only happen if the caller reuses w after it's
 10519  		// been intentionally nil'ed out to prevent use. Keep this
 10520  		// here to catch future refactoring breaking it.
 10521  		panic("writeEndsStream called on nil writeFramer")
 10522  	}
 10523  	return false
 10524  }
 10525  
 10526  type http2flushFrameWriter struct{}
 10527  
 10528  func (http2flushFrameWriter) writeFrame(ctx http2writeContext) error {
 10529  	return ctx.Flush()
 10530  }
 10531  
 10532  func (http2flushFrameWriter) staysWithinBuffer(max int) bool { return false }
 10533  
 10534  type http2writeSettings []http2Setting
 10535  
 10536  func (s http2writeSettings) staysWithinBuffer(max int) bool {
 10537  	const settingSize = 6 // uint16 + uint32
 10538  	return http2frameHeaderLen+settingSize*len(s) <= max
 10539  
 10540  }
 10541  
 10542  func (s http2writeSettings) writeFrame(ctx http2writeContext) error {
 10543  	return ctx.Framer().WriteSettings([]http2Setting(s)...)
 10544  }
 10545  
 10546  type http2writeGoAway struct {
 10547  	maxStreamID uint32
 10548  	code        http2ErrCode
 10549  }
 10550  
 10551  func (p *http2writeGoAway) writeFrame(ctx http2writeContext) error {
 10552  	err := ctx.Framer().WriteGoAway(p.maxStreamID, p.code, nil)
 10553  	ctx.Flush() // ignore error: we're hanging up on them anyway
 10554  	return err
 10555  }
 10556  
 10557  func (*http2writeGoAway) staysWithinBuffer(max int) bool { return false } // flushes
 10558  
 10559  type http2writeData struct {
 10560  	streamID  uint32
 10561  	p         []byte
 10562  	endStream bool
 10563  }
 10564  
 10565  func (w *http2writeData) String() string {
 10566  	return fmt.Sprintf("writeData(stream=%d, p=%d, endStream=%v)", w.streamID, len(w.p), w.endStream)
 10567  }
 10568  
 10569  func (w *http2writeData) writeFrame(ctx http2writeContext) error {
 10570  	return ctx.Framer().WriteData(w.streamID, w.endStream, w.p)
 10571  }
 10572  
 10573  func (w *http2writeData) staysWithinBuffer(max int) bool {
 10574  	return http2frameHeaderLen+len(w.p) <= max
 10575  }
 10576  
 10577  // handlerPanicRST is the message sent from handler goroutines when
 10578  // the handler panics.
 10579  type http2handlerPanicRST struct {
 10580  	StreamID uint32
 10581  }
 10582  
 10583  func (hp http2handlerPanicRST) writeFrame(ctx http2writeContext) error {
 10584  	return ctx.Framer().WriteRSTStream(hp.StreamID, http2ErrCodeInternal)
 10585  }
 10586  
 10587  func (hp http2handlerPanicRST) staysWithinBuffer(max int) bool { return http2frameHeaderLen+4 <= max }
 10588  
 10589  func (se http2StreamError) writeFrame(ctx http2writeContext) error {
 10590  	return ctx.Framer().WriteRSTStream(se.StreamID, se.Code)
 10591  }
 10592  
 10593  func (se http2StreamError) staysWithinBuffer(max int) bool { return http2frameHeaderLen+4 <= max }
 10594  
 10595  type http2writePingAck struct{ pf *http2PingFrame }
 10596  
 10597  func (w http2writePingAck) writeFrame(ctx http2writeContext) error {
 10598  	return ctx.Framer().WritePing(true, w.pf.Data)
 10599  }
 10600  
 10601  func (w http2writePingAck) staysWithinBuffer(max int) bool {
 10602  	return http2frameHeaderLen+len(w.pf.Data) <= max
 10603  }
 10604  
 10605  type http2writeSettingsAck struct{}
 10606  
 10607  func (http2writeSettingsAck) writeFrame(ctx http2writeContext) error {
 10608  	return ctx.Framer().WriteSettingsAck()
 10609  }
 10610  
 10611  func (http2writeSettingsAck) staysWithinBuffer(max int) bool { return http2frameHeaderLen <= max }
 10612  
 10613  // splitHeaderBlock splits headerBlock into fragments so that each fragment fits
 10614  // in a single frame, then calls fn for each fragment. firstFrag/lastFrag are true
 10615  // for the first/last fragment, respectively.
 10616  func http2splitHeaderBlock(ctx http2writeContext, headerBlock []byte, fn func(ctx http2writeContext, frag []byte, firstFrag, lastFrag bool) error) error {
 10617  	// For now we're lazy and just pick the minimum MAX_FRAME_SIZE
 10618  	// that all peers must support (16KB). Later we could care
 10619  	// more and send larger frames if the peer advertised it, but
 10620  	// there's little point. Most headers are small anyway (so we
 10621  	// generally won't have CONTINUATION frames), and extra frames
 10622  	// only waste 9 bytes anyway.
 10623  	const maxFrameSize = 16384
 10624  
 10625  	first := true
 10626  	for len(headerBlock) > 0 {
 10627  		frag := headerBlock
 10628  		if len(frag) > maxFrameSize {
 10629  			frag = frag[:maxFrameSize]
 10630  		}
 10631  		headerBlock = headerBlock[len(frag):]
 10632  		if err := fn(ctx, frag, first, len(headerBlock) == 0); err != nil {
 10633  			return err
 10634  		}
 10635  		first = false
 10636  	}
 10637  	return nil
 10638  }
 10639  
 10640  // writeResHeaders is a request to write a HEADERS and 0+ CONTINUATION frames
 10641  // for HTTP response headers or trailers from a server handler.
 10642  type http2writeResHeaders struct {
 10643  	streamID    uint32
 10644  	httpResCode int      // 0 means no ":status" line
 10645  	h           Header   // may be nil
 10646  	trailers    []string // if non-nil, which keys of h to write. nil means all.
 10647  	endStream   bool
 10648  
 10649  	date          string
 10650  	contentType   string
 10651  	contentLength string
 10652  }
 10653  
 10654  func http2encKV(enc *hpack.Encoder, k, v string) {
 10655  	if http2VerboseLogs {
 10656  		log.Printf("http2: server encoding header %q = %q", k, v)
 10657  	}
 10658  	enc.WriteField(hpack.HeaderField{Name: k, Value: v})
 10659  }
 10660  
 10661  func (w *http2writeResHeaders) staysWithinBuffer(max int) bool {
 10662  	// TODO: this is a common one. It'd be nice to return true
 10663  	// here and get into the fast path if we could be clever and
 10664  	// calculate the size fast enough, or at least a conservative
 10665  	// upper bound that usually fires. (Maybe if w.h and
 10666  	// w.trailers are nil, so we don't need to enumerate it.)
 10667  	// Otherwise I'm afraid that just calculating the length to
 10668  	// answer this question would be slower than the ~2µs benefit.
 10669  	return false
 10670  }
 10671  
 10672  func (w *http2writeResHeaders) writeFrame(ctx http2writeContext) error {
 10673  	enc, buf := ctx.HeaderEncoder()
 10674  	buf.Reset()
 10675  
 10676  	if w.httpResCode != 0 {
 10677  		http2encKV(enc, ":status", http2httpCodeString(w.httpResCode))
 10678  	}
 10679  
 10680  	http2encodeHeaders(enc, w.h, w.trailers)
 10681  
 10682  	if w.contentType != "" {
 10683  		http2encKV(enc, "content-type", w.contentType)
 10684  	}
 10685  	if w.contentLength != "" {
 10686  		http2encKV(enc, "content-length", w.contentLength)
 10687  	}
 10688  	if w.date != "" {
 10689  		http2encKV(enc, "date", w.date)
 10690  	}
 10691  
 10692  	headerBlock := buf.Bytes()
 10693  	if len(headerBlock) == 0 && w.trailers == nil {
 10694  		panic("unexpected empty hpack")
 10695  	}
 10696  
 10697  	return http2splitHeaderBlock(ctx, headerBlock, w.writeHeaderBlock)
 10698  }
 10699  
 10700  func (w *http2writeResHeaders) writeHeaderBlock(ctx http2writeContext, frag []byte, firstFrag, lastFrag bool) error {
 10701  	if firstFrag {
 10702  		return ctx.Framer().WriteHeaders(http2HeadersFrameParam{
 10703  			StreamID:      w.streamID,
 10704  			BlockFragment: frag,
 10705  			EndStream:     w.endStream,
 10706  			EndHeaders:    lastFrag,
 10707  		})
 10708  	} else {
 10709  		return ctx.Framer().WriteContinuation(w.streamID, lastFrag, frag)
 10710  	}
 10711  }
 10712  
 10713  // writePushPromise is a request to write a PUSH_PROMISE and 0+ CONTINUATION frames.
 10714  type http2writePushPromise struct {
 10715  	streamID uint32   // pusher stream
 10716  	method   string   // for :method
 10717  	url      *url.URL // for :scheme, :authority, :path
 10718  	h        Header
 10719  
 10720  	// Creates an ID for a pushed stream. This runs on serveG just before
 10721  	// the frame is written. The returned ID is copied to promisedID.
 10722  	allocatePromisedID func() (uint32, error)
 10723  	promisedID         uint32
 10724  }
 10725  
 10726  func (w *http2writePushPromise) staysWithinBuffer(max int) bool {
 10727  	// TODO: see writeResHeaders.staysWithinBuffer
 10728  	return false
 10729  }
 10730  
 10731  func (w *http2writePushPromise) writeFrame(ctx http2writeContext) error {
 10732  	enc, buf := ctx.HeaderEncoder()
 10733  	buf.Reset()
 10734  
 10735  	http2encKV(enc, ":method", w.method)
 10736  	http2encKV(enc, ":scheme", w.url.Scheme)
 10737  	http2encKV(enc, ":authority", w.url.Host)
 10738  	http2encKV(enc, ":path", w.url.RequestURI())
 10739  	http2encodeHeaders(enc, w.h, nil)
 10740  
 10741  	headerBlock := buf.Bytes()
 10742  	if len(headerBlock) == 0 {
 10743  		panic("unexpected empty hpack")
 10744  	}
 10745  
 10746  	return http2splitHeaderBlock(ctx, headerBlock, w.writeHeaderBlock)
 10747  }
 10748  
 10749  func (w *http2writePushPromise) writeHeaderBlock(ctx http2writeContext, frag []byte, firstFrag, lastFrag bool) error {
 10750  	if firstFrag {
 10751  		return ctx.Framer().WritePushPromise(http2PushPromiseParam{
 10752  			StreamID:      w.streamID,
 10753  			PromiseID:     w.promisedID,
 10754  			BlockFragment: frag,
 10755  			EndHeaders:    lastFrag,
 10756  		})
 10757  	} else {
 10758  		return ctx.Framer().WriteContinuation(w.streamID, lastFrag, frag)
 10759  	}
 10760  }
 10761  
 10762  type http2write100ContinueHeadersFrame struct {
 10763  	streamID uint32
 10764  }
 10765  
 10766  func (w http2write100ContinueHeadersFrame) writeFrame(ctx http2writeContext) error {
 10767  	enc, buf := ctx.HeaderEncoder()
 10768  	buf.Reset()
 10769  	http2encKV(enc, ":status", "100")
 10770  	return ctx.Framer().WriteHeaders(http2HeadersFrameParam{
 10771  		StreamID:      w.streamID,
 10772  		BlockFragment: buf.Bytes(),
 10773  		EndStream:     false,
 10774  		EndHeaders:    true,
 10775  	})
 10776  }
 10777  
 10778  func (w http2write100ContinueHeadersFrame) staysWithinBuffer(max int) bool {
 10779  	// Sloppy but conservative:
 10780  	return 9+2*(len(":status")+len("100")) <= max
 10781  }
 10782  
 10783  type http2writeWindowUpdate struct {
 10784  	streamID uint32 // or 0 for conn-level
 10785  	n        uint32
 10786  }
 10787  
 10788  func (wu http2writeWindowUpdate) staysWithinBuffer(max int) bool { return http2frameHeaderLen+4 <= max }
 10789  
 10790  func (wu http2writeWindowUpdate) writeFrame(ctx http2writeContext) error {
 10791  	return ctx.Framer().WriteWindowUpdate(wu.streamID, wu.n)
 10792  }
 10793  
 10794  // encodeHeaders encodes an http.Header. If keys is not nil, then (k, h[k])
 10795  // is encoded only if k is in keys.
 10796  func http2encodeHeaders(enc *hpack.Encoder, h Header, keys []string) {
 10797  	if keys == nil {
 10798  		sorter := http2sorterPool.Get().(*http2sorter)
 10799  		// Using defer here, since the returned keys from the
 10800  		// sorter.Keys method is only valid until the sorter
 10801  		// is returned:
 10802  		defer http2sorterPool.Put(sorter)
 10803  		keys = sorter.Keys(h)
 10804  	}
 10805  	for _, k := range keys {
 10806  		vv := h[k]
 10807  		k, ascii := http2lowerHeader(k)
 10808  		if !ascii {
 10809  			// Skip writing invalid headers. Per RFC 7540, Section 8.1.2, header
 10810  			// field names have to be ASCII characters (just as in HTTP/1.x).
 10811  			continue
 10812  		}
 10813  		if !http2validWireHeaderFieldName(k) {
 10814  			// Skip it as backup paranoia. Per
 10815  			// golang.org/issue/14048, these should
 10816  			// already be rejected at a higher level.
 10817  			continue
 10818  		}
 10819  		isTE := k == "transfer-encoding"
 10820  		for _, v := range vv {
 10821  			if !httpguts.ValidHeaderFieldValue(v) {
 10822  				// TODO: return an error? golang.org/issue/14048
 10823  				// For now just omit it.
 10824  				continue
 10825  			}
 10826  			// TODO: more of "8.1.2.2 Connection-Specific Header Fields"
 10827  			if isTE && v != "trailers" {
 10828  				continue
 10829  			}
 10830  			http2encKV(enc, k, v)
 10831  		}
 10832  	}
 10833  }
 10834  
 10835  // WriteScheduler is the interface implemented by HTTP/2 write schedulers.
 10836  // Methods are never called concurrently.
 10837  type http2WriteScheduler interface {
 10838  	// OpenStream opens a new stream in the write scheduler.
 10839  	// It is illegal to call this with streamID=0 or with a streamID that is
 10840  	// already open -- the call may panic.
 10841  	OpenStream(streamID uint32, options http2OpenStreamOptions)
 10842  
 10843  	// CloseStream closes a stream in the write scheduler. Any frames queued on
 10844  	// this stream should be discarded. It is illegal to call this on a stream
 10845  	// that is not open -- the call may panic.
 10846  	CloseStream(streamID uint32)
 10847  
 10848  	// AdjustStream adjusts the priority of the given stream. This may be called
 10849  	// on a stream that has not yet been opened or has been closed. Note that
 10850  	// RFC 7540 allows PRIORITY frames to be sent on streams in any state. See:
 10851  	// https://tools.ietf.org/html/rfc7540#section-5.1
 10852  	AdjustStream(streamID uint32, priority http2PriorityParam)
 10853  
 10854  	// Push queues a frame in the scheduler. In most cases, this will not be
 10855  	// called with wr.StreamID()!=0 unless that stream is currently open. The one
 10856  	// exception is RST_STREAM frames, which may be sent on idle or closed streams.
 10857  	Push(wr http2FrameWriteRequest)
 10858  
 10859  	// Pop dequeues the next frame to write. Returns false if no frames can
 10860  	// be written. Frames with a given wr.StreamID() are Pop'd in the same
 10861  	// order they are Push'd, except RST_STREAM frames. No frames should be
 10862  	// discarded except by CloseStream.
 10863  	Pop() (wr http2FrameWriteRequest, ok bool)
 10864  }
 10865  
 10866  // OpenStreamOptions specifies extra options for WriteScheduler.OpenStream.
 10867  type http2OpenStreamOptions struct {
 10868  	// PusherID is zero if the stream was initiated by the client. Otherwise,
 10869  	// PusherID names the stream that pushed the newly opened stream.
 10870  	PusherID uint32
 10871  }
 10872  
 10873  // FrameWriteRequest is a request to write a frame.
 10874  type http2FrameWriteRequest struct {
 10875  	// write is the interface value that does the writing, once the
 10876  	// WriteScheduler has selected this frame to write. The write
 10877  	// functions are all defined in write.go.
 10878  	write http2writeFramer
 10879  
 10880  	// stream is the stream on which this frame will be written.
 10881  	// nil for non-stream frames like PING and SETTINGS.
 10882  	// nil for RST_STREAM streams, which use the StreamError.StreamID field instead.
 10883  	stream *http2stream
 10884  
 10885  	// done, if non-nil, must be a buffered channel with space for
 10886  	// 1 message and is sent the return value from write (or an
 10887  	// earlier error) when the frame has been written.
 10888  	done chan error
 10889  }
 10890  
 10891  // StreamID returns the id of the stream this frame will be written to.
 10892  // 0 is used for non-stream frames such as PING and SETTINGS.
 10893  func (wr http2FrameWriteRequest) StreamID() uint32 {
 10894  	if wr.stream == nil {
 10895  		if se, ok := wr.write.(http2StreamError); ok {
 10896  			// (*serverConn).resetStream doesn't set
 10897  			// stream because it doesn't necessarily have
 10898  			// one. So special case this type of write
 10899  			// message.
 10900  			return se.StreamID
 10901  		}
 10902  		return 0
 10903  	}
 10904  	return wr.stream.id
 10905  }
 10906  
 10907  // isControl reports whether wr is a control frame for MaxQueuedControlFrames
 10908  // purposes. That includes non-stream frames and RST_STREAM frames.
 10909  func (wr http2FrameWriteRequest) isControl() bool {
 10910  	return wr.stream == nil
 10911  }
 10912  
 10913  // DataSize returns the number of flow control bytes that must be consumed
 10914  // to write this entire frame. This is 0 for non-DATA frames.
 10915  func (wr http2FrameWriteRequest) DataSize() int {
 10916  	if wd, ok := wr.write.(*http2writeData); ok {
 10917  		return len(wd.p)
 10918  	}
 10919  	return 0
 10920  }
 10921  
 10922  // Consume consumes min(n, available) bytes from this frame, where available
 10923  // is the number of flow control bytes available on the stream. Consume returns
 10924  // 0, 1, or 2 frames, where the integer return value gives the number of frames
 10925  // returned.
 10926  //
 10927  // If flow control prevents consuming any bytes, this returns (_, _, 0). If
 10928  // the entire frame was consumed, this returns (wr, _, 1). Otherwise, this
 10929  // returns (consumed, rest, 2), where 'consumed' contains the consumed bytes and
 10930  // 'rest' contains the remaining bytes. The consumed bytes are deducted from the
 10931  // underlying stream's flow control budget.
 10932  func (wr http2FrameWriteRequest) Consume(n int32) (http2FrameWriteRequest, http2FrameWriteRequest, int) {
 10933  	var empty http2FrameWriteRequest
 10934  
 10935  	// Non-DATA frames are always consumed whole.
 10936  	wd, ok := wr.write.(*http2writeData)
 10937  	if !ok || len(wd.p) == 0 {
 10938  		return wr, empty, 1
 10939  	}
 10940  
 10941  	// Might need to split after applying limits.
 10942  	allowed := wr.stream.flow.available()
 10943  	if n < allowed {
 10944  		allowed = n
 10945  	}
 10946  	if wr.stream.sc.maxFrameSize < allowed {
 10947  		allowed = wr.stream.sc.maxFrameSize
 10948  	}
 10949  	if allowed <= 0 {
 10950  		return empty, empty, 0
 10951  	}
 10952  	if len(wd.p) > int(allowed) {
 10953  		wr.stream.flow.take(allowed)
 10954  		consumed := http2FrameWriteRequest{
 10955  			stream: wr.stream,
 10956  			write: &http2writeData{
 10957  				streamID: wd.streamID,
 10958  				p:        wd.p[:allowed],
 10959  				// Even if the original had endStream set, there
 10960  				// are bytes remaining because len(wd.p) > allowed,
 10961  				// so we know endStream is false.
 10962  				endStream: false,
 10963  			},
 10964  			// Our caller is blocking on the final DATA frame, not
 10965  			// this intermediate frame, so no need to wait.
 10966  			done: nil,
 10967  		}
 10968  		rest := http2FrameWriteRequest{
 10969  			stream: wr.stream,
 10970  			write: &http2writeData{
 10971  				streamID:  wd.streamID,
 10972  				p:         wd.p[allowed:],
 10973  				endStream: wd.endStream,
 10974  			},
 10975  			done: wr.done,
 10976  		}
 10977  		return consumed, rest, 2
 10978  	}
 10979  
 10980  	// The frame is consumed whole.
 10981  	// NB: This cast cannot overflow because allowed is <= math.MaxInt32.
 10982  	wr.stream.flow.take(int32(len(wd.p)))
 10983  	return wr, empty, 1
 10984  }
 10985  
 10986  // String is for debugging only.
 10987  func (wr http2FrameWriteRequest) String() string {
 10988  	var des string
 10989  	if s, ok := wr.write.(fmt.Stringer); ok {
 10990  		des = s.String()
 10991  	} else {
 10992  		des = fmt.Sprintf("%T", wr.write)
 10993  	}
 10994  	return fmt.Sprintf("[FrameWriteRequest stream=%d, ch=%v, writer=%v]", wr.StreamID(), wr.done != nil, des)
 10995  }
 10996  
 10997  // replyToWriter sends err to wr.done and panics if the send must block
 10998  // This does nothing if wr.done is nil.
 10999  func (wr *http2FrameWriteRequest) replyToWriter(err error) {
 11000  	if wr.done == nil {
 11001  		return
 11002  	}
 11003  	select {
 11004  	case wr.done <- err:
 11005  	default:
 11006  		panic(fmt.Sprintf("unbuffered done channel passed in for type %T", wr.write))
 11007  	}
 11008  	wr.write = nil // prevent use (assume it's tainted after wr.done send)
 11009  }
 11010  
 11011  // writeQueue is used by implementations of WriteScheduler.
 11012  type http2writeQueue struct {
 11013  	s          []http2FrameWriteRequest
 11014  	prev, next *http2writeQueue
 11015  }
 11016  
 11017  func (q *http2writeQueue) empty() bool { return len(q.s) == 0 }
 11018  
 11019  func (q *http2writeQueue) push(wr http2FrameWriteRequest) {
 11020  	q.s = append(q.s, wr)
 11021  }
 11022  
 11023  func (q *http2writeQueue) shift() http2FrameWriteRequest {
 11024  	if len(q.s) == 0 {
 11025  		panic("invalid use of queue")
 11026  	}
 11027  	wr := q.s[0]
 11028  	// TODO: less copy-happy queue.
 11029  	copy(q.s, q.s[1:])
 11030  	q.s[len(q.s)-1] = http2FrameWriteRequest{}
 11031  	q.s = q.s[:len(q.s)-1]
 11032  	return wr
 11033  }
 11034  
 11035  // consume consumes up to n bytes from q.s[0]. If the frame is
 11036  // entirely consumed, it is removed from the queue. If the frame
 11037  // is partially consumed, the frame is kept with the consumed
 11038  // bytes removed. Returns true iff any bytes were consumed.
 11039  func (q *http2writeQueue) consume(n int32) (http2FrameWriteRequest, bool) {
 11040  	if len(q.s) == 0 {
 11041  		return http2FrameWriteRequest{}, false
 11042  	}
 11043  	consumed, rest, numresult := q.s[0].Consume(n)
 11044  	switch numresult {
 11045  	case 0:
 11046  		return http2FrameWriteRequest{}, false
 11047  	case 1:
 11048  		q.shift()
 11049  	case 2:
 11050  		q.s[0] = rest
 11051  	}
 11052  	return consumed, true
 11053  }
 11054  
 11055  type http2writeQueuePool []*http2writeQueue
 11056  
 11057  // put inserts an unused writeQueue into the pool.
 11058  
 11059  // put inserts an unused writeQueue into the pool.
 11060  func (p *http2writeQueuePool) put(q *http2writeQueue) {
 11061  	for i := range q.s {
 11062  		q.s[i] = http2FrameWriteRequest{}
 11063  	}
 11064  	q.s = q.s[:0]
 11065  	*p = append(*p, q)
 11066  }
 11067  
 11068  // get returns an empty writeQueue.
 11069  func (p *http2writeQueuePool) get() *http2writeQueue {
 11070  	ln := len(*p)
 11071  	if ln == 0 {
 11072  		return new(http2writeQueue)
 11073  	}
 11074  	x := ln - 1
 11075  	q := (*p)[x]
 11076  	(*p)[x] = nil
 11077  	*p = (*p)[:x]
 11078  	return q
 11079  }
 11080  
 11081  // RFC 7540, Section 5.3.5: the default weight is 16.
 11082  const http2priorityDefaultWeight = 15 // 16 = 15 + 1
 11083  
 11084  // PriorityWriteSchedulerConfig configures a priorityWriteScheduler.
 11085  type http2PriorityWriteSchedulerConfig struct {
 11086  	// MaxClosedNodesInTree controls the maximum number of closed streams to
 11087  	// retain in the priority tree. Setting this to zero saves a small amount
 11088  	// of memory at the cost of performance.
 11089  	//
 11090  	// See RFC 7540, Section 5.3.4:
 11091  	//   "It is possible for a stream to become closed while prioritization
 11092  	//   information ... is in transit. ... This potentially creates suboptimal
 11093  	//   prioritization, since the stream could be given a priority that is
 11094  	//   different from what is intended. To avoid these problems, an endpoint
 11095  	//   SHOULD retain stream prioritization state for a period after streams
 11096  	//   become closed. The longer state is retained, the lower the chance that
 11097  	//   streams are assigned incorrect or default priority values."
 11098  	MaxClosedNodesInTree int
 11099  
 11100  	// MaxIdleNodesInTree controls the maximum number of idle streams to
 11101  	// retain in the priority tree. Setting this to zero saves a small amount
 11102  	// of memory at the cost of performance.
 11103  	//
 11104  	// See RFC 7540, Section 5.3.4:
 11105  	//   Similarly, streams that are in the "idle" state can be assigned
 11106  	//   priority or become a parent of other streams. This allows for the
 11107  	//   creation of a grouping node in the dependency tree, which enables
 11108  	//   more flexible expressions of priority. Idle streams begin with a
 11109  	//   default priority (Section 5.3.5).
 11110  	MaxIdleNodesInTree int
 11111  
 11112  	// ThrottleOutOfOrderWrites enables write throttling to help ensure that
 11113  	// data is delivered in priority order. This works around a race where
 11114  	// stream B depends on stream A and both streams are about to call Write
 11115  	// to queue DATA frames. If B wins the race, a naive scheduler would eagerly
 11116  	// write as much data from B as possible, but this is suboptimal because A
 11117  	// is a higher-priority stream. With throttling enabled, we write a small
 11118  	// amount of data from B to minimize the amount of bandwidth that B can
 11119  	// steal from A.
 11120  	ThrottleOutOfOrderWrites bool
 11121  }
 11122  
 11123  // NewPriorityWriteScheduler constructs a WriteScheduler that schedules
 11124  // frames by following HTTP/2 priorities as described in RFC 7540 Section 5.3.
 11125  // If cfg is nil, default options are used.
 11126  func http2NewPriorityWriteScheduler(cfg *http2PriorityWriteSchedulerConfig) http2WriteScheduler {
 11127  	if cfg == nil {
 11128  		// For justification of these defaults, see:
 11129  		// https://docs.google.com/document/d/1oLhNg1skaWD4_DtaoCxdSRN5erEXrH-KnLrMwEpOtFY
 11130  		cfg = &http2PriorityWriteSchedulerConfig{
 11131  			MaxClosedNodesInTree:     10,
 11132  			MaxIdleNodesInTree:       10,
 11133  			ThrottleOutOfOrderWrites: false,
 11134  		}
 11135  	}
 11136  
 11137  	ws := &http2priorityWriteScheduler{
 11138  		nodes:                make(map[uint32]*http2priorityNode),
 11139  		maxClosedNodesInTree: cfg.MaxClosedNodesInTree,
 11140  		maxIdleNodesInTree:   cfg.MaxIdleNodesInTree,
 11141  		enableWriteThrottle:  cfg.ThrottleOutOfOrderWrites,
 11142  	}
 11143  	ws.nodes[0] = &ws.root
 11144  	if cfg.ThrottleOutOfOrderWrites {
 11145  		ws.writeThrottleLimit = 1024
 11146  	} else {
 11147  		ws.writeThrottleLimit = math.MaxInt32
 11148  	}
 11149  	return ws
 11150  }
 11151  
 11152  type http2priorityNodeState int
 11153  
 11154  const (
 11155  	http2priorityNodeOpen http2priorityNodeState = iota
 11156  	http2priorityNodeClosed
 11157  	http2priorityNodeIdle
 11158  )
 11159  
 11160  // priorityNode is a node in an HTTP/2 priority tree.
 11161  // Each node is associated with a single stream ID.
 11162  // See RFC 7540, Section 5.3.
 11163  type http2priorityNode struct {
 11164  	q            http2writeQueue        // queue of pending frames to write
 11165  	id           uint32                 // id of the stream, or 0 for the root of the tree
 11166  	weight       uint8                  // the actual weight is weight+1, so the value is in [1,256]
 11167  	state        http2priorityNodeState // open | closed | idle
 11168  	bytes        int64                  // number of bytes written by this node, or 0 if closed
 11169  	subtreeBytes int64                  // sum(node.bytes) of all nodes in this subtree
 11170  
 11171  	// These links form the priority tree.
 11172  	parent     *http2priorityNode
 11173  	kids       *http2priorityNode // start of the kids list
 11174  	prev, next *http2priorityNode // doubly-linked list of siblings
 11175  }
 11176  
 11177  func (n *http2priorityNode) setParent(parent *http2priorityNode) {
 11178  	if n == parent {
 11179  		panic("setParent to self")
 11180  	}
 11181  	if n.parent == parent {
 11182  		return
 11183  	}
 11184  	// Unlink from current parent.
 11185  	if parent := n.parent; parent != nil {
 11186  		if n.prev == nil {
 11187  			parent.kids = n.next
 11188  		} else {
 11189  			n.prev.next = n.next
 11190  		}
 11191  		if n.next != nil {
 11192  			n.next.prev = n.prev
 11193  		}
 11194  	}
 11195  	// Link to new parent.
 11196  	// If parent=nil, remove n from the tree.
 11197  	// Always insert at the head of parent.kids (this is assumed by walkReadyInOrder).
 11198  	n.parent = parent
 11199  	if parent == nil {
 11200  		n.next = nil
 11201  		n.prev = nil
 11202  	} else {
 11203  		n.next = parent.kids
 11204  		n.prev = nil
 11205  		if n.next != nil {
 11206  			n.next.prev = n
 11207  		}
 11208  		parent.kids = n
 11209  	}
 11210  }
 11211  
 11212  func (n *http2priorityNode) addBytes(b int64) {
 11213  	n.bytes += b
 11214  	for ; n != nil; n = n.parent {
 11215  		n.subtreeBytes += b
 11216  	}
 11217  }
 11218  
 11219  // walkReadyInOrder iterates over the tree in priority order, calling f for each node
 11220  // with a non-empty write queue. When f returns true, this function returns true and the
 11221  // walk halts. tmp is used as scratch space for sorting.
 11222  //
 11223  // f(n, openParent) takes two arguments: the node to visit, n, and a bool that is true
 11224  // if any ancestor p of n is still open (ignoring the root node).
 11225  func (n *http2priorityNode) walkReadyInOrder(openParent bool, tmp *[]*http2priorityNode, f func(*http2priorityNode, bool) bool) bool {
 11226  	if !n.q.empty() && f(n, openParent) {
 11227  		return true
 11228  	}
 11229  	if n.kids == nil {
 11230  		return false
 11231  	}
 11232  
 11233  	// Don't consider the root "open" when updating openParent since
 11234  	// we can't send data frames on the root stream (only control frames).
 11235  	if n.id != 0 {
 11236  		openParent = openParent || (n.state == http2priorityNodeOpen)
 11237  	}
 11238  
 11239  	// Common case: only one kid or all kids have the same weight.
 11240  	// Some clients don't use weights; other clients (like web browsers)
 11241  	// use mostly-linear priority trees.
 11242  	w := n.kids.weight
 11243  	needSort := false
 11244  	for k := n.kids.next; k != nil; k = k.next {
 11245  		if k.weight != w {
 11246  			needSort = true
 11247  			break
 11248  		}
 11249  	}
 11250  	if !needSort {
 11251  		for k := n.kids; k != nil; k = k.next {
 11252  			if k.walkReadyInOrder(openParent, tmp, f) {
 11253  				return true
 11254  			}
 11255  		}
 11256  		return false
 11257  	}
 11258  
 11259  	// Uncommon case: sort the child nodes. We remove the kids from the parent,
 11260  	// then re-insert after sorting so we can reuse tmp for future sort calls.
 11261  	*tmp = (*tmp)[:0]
 11262  	for n.kids != nil {
 11263  		*tmp = append(*tmp, n.kids)
 11264  		n.kids.setParent(nil)
 11265  	}
 11266  	sort.Sort(http2sortPriorityNodeSiblings(*tmp))
 11267  	for i := len(*tmp) - 1; i >= 0; i-- {
 11268  		(*tmp)[i].setParent(n) // setParent inserts at the head of n.kids
 11269  	}
 11270  	for k := n.kids; k != nil; k = k.next {
 11271  		if k.walkReadyInOrder(openParent, tmp, f) {
 11272  			return true
 11273  		}
 11274  	}
 11275  	return false
 11276  }
 11277  
 11278  type http2sortPriorityNodeSiblings []*http2priorityNode
 11279  
 11280  func (z http2sortPriorityNodeSiblings) Len() int { return len(z) }
 11281  
 11282  func (z http2sortPriorityNodeSiblings) Swap(i, k int) { z[i], z[k] = z[k], z[i] }
 11283  
 11284  func (z http2sortPriorityNodeSiblings) Less(i, k int) bool {
 11285  	// Prefer the subtree that has sent fewer bytes relative to its weight.
 11286  	// See sections 5.3.2 and 5.3.4.
 11287  	wi, bi := float64(z[i].weight+1), float64(z[i].subtreeBytes)
 11288  	wk, bk := float64(z[k].weight+1), float64(z[k].subtreeBytes)
 11289  	if bi == 0 && bk == 0 {
 11290  		return wi >= wk
 11291  	}
 11292  	if bk == 0 {
 11293  		return false
 11294  	}
 11295  	return bi/bk <= wi/wk
 11296  }
 11297  
 11298  type http2priorityWriteScheduler struct {
 11299  	// root is the root of the priority tree, where root.id = 0.
 11300  	// The root queues control frames that are not associated with any stream.
 11301  	root http2priorityNode
 11302  
 11303  	// nodes maps stream ids to priority tree nodes.
 11304  	nodes map[uint32]*http2priorityNode
 11305  
 11306  	// maxID is the maximum stream id in nodes.
 11307  	maxID uint32
 11308  
 11309  	// lists of nodes that have been closed or are idle, but are kept in
 11310  	// the tree for improved prioritization. When the lengths exceed either
 11311  	// maxClosedNodesInTree or maxIdleNodesInTree, old nodes are discarded.
 11312  	closedNodes, idleNodes []*http2priorityNode
 11313  
 11314  	// From the config.
 11315  	maxClosedNodesInTree int
 11316  	maxIdleNodesInTree   int
 11317  	writeThrottleLimit   int32
 11318  	enableWriteThrottle  bool
 11319  
 11320  	// tmp is scratch space for priorityNode.walkReadyInOrder to reduce allocations.
 11321  	tmp []*http2priorityNode
 11322  
 11323  	// pool of empty queues for reuse.
 11324  	queuePool http2writeQueuePool
 11325  }
 11326  
 11327  func (ws *http2priorityWriteScheduler) OpenStream(streamID uint32, options http2OpenStreamOptions) {
 11328  	// The stream may be currently idle but cannot be opened or closed.
 11329  	if curr := ws.nodes[streamID]; curr != nil {
 11330  		if curr.state != http2priorityNodeIdle {
 11331  			panic(fmt.Sprintf("stream %d already opened", streamID))
 11332  		}
 11333  		curr.state = http2priorityNodeOpen
 11334  		return
 11335  	}
 11336  
 11337  	// RFC 7540, Section 5.3.5:
 11338  	//  "All streams are initially assigned a non-exclusive dependency on stream 0x0.
 11339  	//  Pushed streams initially depend on their associated stream. In both cases,
 11340  	//  streams are assigned a default weight of 16."
 11341  	parent := ws.nodes[options.PusherID]
 11342  	if parent == nil {
 11343  		parent = &ws.root
 11344  	}
 11345  	n := &http2priorityNode{
 11346  		q:      *ws.queuePool.get(),
 11347  		id:     streamID,
 11348  		weight: http2priorityDefaultWeight,
 11349  		state:  http2priorityNodeOpen,
 11350  	}
 11351  	n.setParent(parent)
 11352  	ws.nodes[streamID] = n
 11353  	if streamID > ws.maxID {
 11354  		ws.maxID = streamID
 11355  	}
 11356  }
 11357  
 11358  func (ws *http2priorityWriteScheduler) CloseStream(streamID uint32) {
 11359  	if streamID == 0 {
 11360  		panic("violation of WriteScheduler interface: cannot close stream 0")
 11361  	}
 11362  	if ws.nodes[streamID] == nil {
 11363  		panic(fmt.Sprintf("violation of WriteScheduler interface: unknown stream %d", streamID))
 11364  	}
 11365  	if ws.nodes[streamID].state != http2priorityNodeOpen {
 11366  		panic(fmt.Sprintf("violation of WriteScheduler interface: stream %d already closed", streamID))
 11367  	}
 11368  
 11369  	n := ws.nodes[streamID]
 11370  	n.state = http2priorityNodeClosed
 11371  	n.addBytes(-n.bytes)
 11372  
 11373  	q := n.q
 11374  	ws.queuePool.put(&q)
 11375  	n.q.s = nil
 11376  	if ws.maxClosedNodesInTree > 0 {
 11377  		ws.addClosedOrIdleNode(&ws.closedNodes, ws.maxClosedNodesInTree, n)
 11378  	} else {
 11379  		ws.removeNode(n)
 11380  	}
 11381  }
 11382  
 11383  func (ws *http2priorityWriteScheduler) AdjustStream(streamID uint32, priority http2PriorityParam) {
 11384  	if streamID == 0 {
 11385  		panic("adjustPriority on root")
 11386  	}
 11387  
 11388  	// If streamID does not exist, there are two cases:
 11389  	// - A closed stream that has been removed (this will have ID <= maxID)
 11390  	// - An idle stream that is being used for "grouping" (this will have ID > maxID)
 11391  	n := ws.nodes[streamID]
 11392  	if n == nil {
 11393  		if streamID <= ws.maxID || ws.maxIdleNodesInTree == 0 {
 11394  			return
 11395  		}
 11396  		ws.maxID = streamID
 11397  		n = &http2priorityNode{
 11398  			q:      *ws.queuePool.get(),
 11399  			id:     streamID,
 11400  			weight: http2priorityDefaultWeight,
 11401  			state:  http2priorityNodeIdle,
 11402  		}
 11403  		n.setParent(&ws.root)
 11404  		ws.nodes[streamID] = n
 11405  		ws.addClosedOrIdleNode(&ws.idleNodes, ws.maxIdleNodesInTree, n)
 11406  	}
 11407  
 11408  	// Section 5.3.1: A dependency on a stream that is not currently in the tree
 11409  	// results in that stream being given a default priority (Section 5.3.5).
 11410  	parent := ws.nodes[priority.StreamDep]
 11411  	if parent == nil {
 11412  		n.setParent(&ws.root)
 11413  		n.weight = http2priorityDefaultWeight
 11414  		return
 11415  	}
 11416  
 11417  	// Ignore if the client tries to make a node its own parent.
 11418  	if n == parent {
 11419  		return
 11420  	}
 11421  
 11422  	// Section 5.3.3:
 11423  	//   "If a stream is made dependent on one of its own dependencies, the
 11424  	//   formerly dependent stream is first moved to be dependent on the
 11425  	//   reprioritized stream's previous parent. The moved dependency retains
 11426  	//   its weight."
 11427  	//
 11428  	// That is: if parent depends on n, move parent to depend on n.parent.
 11429  	for x := parent.parent; x != nil; x = x.parent {
 11430  		if x == n {
 11431  			parent.setParent(n.parent)
 11432  			break
 11433  		}
 11434  	}
 11435  
 11436  	// Section 5.3.3: The exclusive flag causes the stream to become the sole
 11437  	// dependency of its parent stream, causing other dependencies to become
 11438  	// dependent on the exclusive stream.
 11439  	if priority.Exclusive {
 11440  		k := parent.kids
 11441  		for k != nil {
 11442  			next := k.next
 11443  			if k != n {
 11444  				k.setParent(n)
 11445  			}
 11446  			k = next
 11447  		}
 11448  	}
 11449  
 11450  	n.setParent(parent)
 11451  	n.weight = priority.Weight
 11452  }
 11453  
 11454  func (ws *http2priorityWriteScheduler) Push(wr http2FrameWriteRequest) {
 11455  	var n *http2priorityNode
 11456  	if wr.isControl() {
 11457  		n = &ws.root
 11458  	} else {
 11459  		id := wr.StreamID()
 11460  		n = ws.nodes[id]
 11461  		if n == nil {
 11462  			// id is an idle or closed stream. wr should not be a HEADERS or
 11463  			// DATA frame. In other case, we push wr onto the root, rather
 11464  			// than creating a new priorityNode.
 11465  			if wr.DataSize() > 0 {
 11466  				panic("add DATA on non-open stream")
 11467  			}
 11468  			n = &ws.root
 11469  		}
 11470  	}
 11471  	n.q.push(wr)
 11472  }
 11473  
 11474  func (ws *http2priorityWriteScheduler) Pop() (wr http2FrameWriteRequest, ok bool) {
 11475  	ws.root.walkReadyInOrder(false, &ws.tmp, func(n *http2priorityNode, openParent bool) bool {
 11476  		limit := int32(math.MaxInt32)
 11477  		if openParent {
 11478  			limit = ws.writeThrottleLimit
 11479  		}
 11480  		wr, ok = n.q.consume(limit)
 11481  		if !ok {
 11482  			return false
 11483  		}
 11484  		n.addBytes(int64(wr.DataSize()))
 11485  		// If B depends on A and B continuously has data available but A
 11486  		// does not, gradually increase the throttling limit to allow B to
 11487  		// steal more and more bandwidth from A.
 11488  		if openParent {
 11489  			ws.writeThrottleLimit += 1024
 11490  			if ws.writeThrottleLimit < 0 {
 11491  				ws.writeThrottleLimit = math.MaxInt32
 11492  			}
 11493  		} else if ws.enableWriteThrottle {
 11494  			ws.writeThrottleLimit = 1024
 11495  		}
 11496  		return true
 11497  	})
 11498  	return wr, ok
 11499  }
 11500  
 11501  func (ws *http2priorityWriteScheduler) addClosedOrIdleNode(list *[]*http2priorityNode, maxSize int, n *http2priorityNode) {
 11502  	if maxSize == 0 {
 11503  		return
 11504  	}
 11505  	if len(*list) == maxSize {
 11506  		// Remove the oldest node, then shift left.
 11507  		ws.removeNode((*list)[0])
 11508  		x := (*list)[1:]
 11509  		copy(*list, x)
 11510  		*list = (*list)[:len(x)]
 11511  	}
 11512  	*list = append(*list, n)
 11513  }
 11514  
 11515  func (ws *http2priorityWriteScheduler) removeNode(n *http2priorityNode) {
 11516  	for n.kids != nil {
 11517  		n.kids.setParent(n.parent)
 11518  	}
 11519  	n.setParent(nil)
 11520  	delete(ws.nodes, n.id)
 11521  }
 11522  
 11523  // NewRandomWriteScheduler constructs a WriteScheduler that ignores HTTP/2
 11524  // priorities. Control frames like SETTINGS and PING are written before DATA
 11525  // frames, but if no control frames are queued and multiple streams have queued
 11526  // HEADERS or DATA frames, Pop selects a ready stream arbitrarily.
 11527  func http2NewRandomWriteScheduler() http2WriteScheduler {
 11528  	return &http2randomWriteScheduler{sq: make(map[uint32]*http2writeQueue)}
 11529  }
 11530  
 11531  type http2randomWriteScheduler struct {
 11532  	// zero are frames not associated with a specific stream.
 11533  	zero http2writeQueue
 11534  
 11535  	// sq contains the stream-specific queues, keyed by stream ID.
 11536  	// When a stream is idle, closed, or emptied, it's deleted
 11537  	// from the map.
 11538  	sq map[uint32]*http2writeQueue
 11539  
 11540  	// pool of empty queues for reuse.
 11541  	queuePool http2writeQueuePool
 11542  }
 11543  
 11544  func (ws *http2randomWriteScheduler) OpenStream(streamID uint32, options http2OpenStreamOptions) {
 11545  	// no-op: idle streams are not tracked
 11546  }
 11547  
 11548  func (ws *http2randomWriteScheduler) CloseStream(streamID uint32) {
 11549  	q, ok := ws.sq[streamID]
 11550  	if !ok {
 11551  		return
 11552  	}
 11553  	delete(ws.sq, streamID)
 11554  	ws.queuePool.put(q)
 11555  }
 11556  
 11557  func (ws *http2randomWriteScheduler) AdjustStream(streamID uint32, priority http2PriorityParam) {
 11558  	// no-op: priorities are ignored
 11559  }
 11560  
 11561  func (ws *http2randomWriteScheduler) Push(wr http2FrameWriteRequest) {
 11562  	if wr.isControl() {
 11563  		ws.zero.push(wr)
 11564  		return
 11565  	}
 11566  	id := wr.StreamID()
 11567  	q, ok := ws.sq[id]
 11568  	if !ok {
 11569  		q = ws.queuePool.get()
 11570  		ws.sq[id] = q
 11571  	}
 11572  	q.push(wr)
 11573  }
 11574  
 11575  func (ws *http2randomWriteScheduler) Pop() (http2FrameWriteRequest, bool) {
 11576  	// Control and RST_STREAM frames first.
 11577  	if !ws.zero.empty() {
 11578  		return ws.zero.shift(), true
 11579  	}
 11580  	// Iterate over all non-idle streams until finding one that can be consumed.
 11581  	for streamID, q := range ws.sq {
 11582  		if wr, ok := q.consume(math.MaxInt32); ok {
 11583  			if q.empty() {
 11584  				delete(ws.sq, streamID)
 11585  				ws.queuePool.put(q)
 11586  			}
 11587  			return wr, true
 11588  		}
 11589  	}
 11590  	return http2FrameWriteRequest{}, false
 11591  }
 11592  
 11593  type http2roundRobinWriteScheduler struct {
 11594  	// control contains control frames (SETTINGS, PING, etc.).
 11595  	control http2writeQueue
 11596  
 11597  	// streams maps stream ID to a queue.
 11598  	streams map[uint32]*http2writeQueue
 11599  
 11600  	// stream queues are stored in a circular linked list.
 11601  	// head is the next stream to write, or nil if there are no streams open.
 11602  	head *http2writeQueue
 11603  
 11604  	// pool of empty queues for reuse.
 11605  	queuePool http2writeQueuePool
 11606  }
 11607  
 11608  // newRoundRobinWriteScheduler constructs a new write scheduler.
 11609  // The round robin scheduler priorizes control frames
 11610  // like SETTINGS and PING over DATA frames.
 11611  // When there are no control frames to send, it performs a round-robin
 11612  // selection from the ready streams.
 11613  func http2newRoundRobinWriteScheduler() http2WriteScheduler {
 11614  	ws := &http2roundRobinWriteScheduler{
 11615  		streams: make(map[uint32]*http2writeQueue),
 11616  	}
 11617  	return ws
 11618  }
 11619  
 11620  func (ws *http2roundRobinWriteScheduler) OpenStream(streamID uint32, options http2OpenStreamOptions) {
 11621  	if ws.streams[streamID] != nil {
 11622  		panic(fmt.Errorf("stream %d already opened", streamID))
 11623  	}
 11624  	q := ws.queuePool.get()
 11625  	ws.streams[streamID] = q
 11626  	if ws.head == nil {
 11627  		ws.head = q
 11628  		q.next = q
 11629  		q.prev = q
 11630  	} else {
 11631  		// Queues are stored in a ring.
 11632  		// Insert the new stream before ws.head, putting it at the end of the list.
 11633  		q.prev = ws.head.prev
 11634  		q.next = ws.head
 11635  		q.prev.next = q
 11636  		q.next.prev = q
 11637  	}
 11638  }
 11639  
 11640  func (ws *http2roundRobinWriteScheduler) CloseStream(streamID uint32) {
 11641  	q := ws.streams[streamID]
 11642  	if q == nil {
 11643  		return
 11644  	}
 11645  	if q.next == q {
 11646  		// This was the only open stream.
 11647  		ws.head = nil
 11648  	} else {
 11649  		q.prev.next = q.next
 11650  		q.next.prev = q.prev
 11651  		if ws.head == q {
 11652  			ws.head = q.next
 11653  		}
 11654  	}
 11655  	delete(ws.streams, streamID)
 11656  	ws.queuePool.put(q)
 11657  }
 11658  
 11659  func (ws *http2roundRobinWriteScheduler) AdjustStream(streamID uint32, priority http2PriorityParam) {}
 11660  
 11661  func (ws *http2roundRobinWriteScheduler) Push(wr http2FrameWriteRequest) {
 11662  	if wr.isControl() {
 11663  		ws.control.push(wr)
 11664  		return
 11665  	}
 11666  	q := ws.streams[wr.StreamID()]
 11667  	if q == nil {
 11668  		// This is a closed stream.
 11669  		// wr should not be a HEADERS or DATA frame.
 11670  		// We push the request onto the control queue.
 11671  		if wr.DataSize() > 0 {
 11672  			panic("add DATA on non-open stream")
 11673  		}
 11674  		ws.control.push(wr)
 11675  		return
 11676  	}
 11677  	q.push(wr)
 11678  }
 11679  
 11680  func (ws *http2roundRobinWriteScheduler) Pop() (http2FrameWriteRequest, bool) {
 11681  	// Control and RST_STREAM frames first.
 11682  	if !ws.control.empty() {
 11683  		return ws.control.shift(), true
 11684  	}
 11685  	if ws.head == nil {
 11686  		return http2FrameWriteRequest{}, false
 11687  	}
 11688  	q := ws.head
 11689  	for {
 11690  		if wr, ok := q.consume(math.MaxInt32); ok {
 11691  			ws.head = q.next
 11692  			return wr, true
 11693  		}
 11694  		q = q.next
 11695  		if q == ws.head {
 11696  			break
 11697  		}
 11698  	}
 11699  	return http2FrameWriteRequest{}, false
 11700  }
 11701  

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