http.go

     1  // Copyright 2016 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  //go:generate bundle -o=h2_bundle.go -prefix=http2 -tags=!nethttpomithttp2 golang.org/x/net/http2
     6  
     7  package http
     8  
     9  import (
    10  	"io"
    11  	"strconv"
    12  	"strings"
    13  	"time"
    14  	"unicode/utf8"
    15  
    16  	"golang.org/x/net/http/httpguts"
    17  )
    18  
    19  // incomparable is a zero-width, non-comparable type. Adding it to a struct
    20  // makes that struct also non-comparable, and generally doesn't add
    21  // any size (as long as it's first).
    22  type incomparable [0]func()
    23  
    24  // maxInt64 is the effective "infinite" value for the Server and
    25  // Transport's byte-limiting readers.
    26  const maxInt64 = 1<<63 - 1
    27  
    28  // aLongTimeAgo is a non-zero time, far in the past, used for
    29  // immediate cancellation of network operations.
    30  var aLongTimeAgo = time.Unix(1, 0)
    31  
    32  // omitBundledHTTP2 is set by omithttp2.go when the nethttpomithttp2
    33  // build tag is set. That means h2_bundle.go isn't compiled in and we
    34  // shouldn't try to use it.
    35  var omitBundledHTTP2 bool
    36  
    37  // TODO(bradfitz): move common stuff here. The other files have accumulated
    38  // generic http stuff in random places.
    39  
    40  // contextKey is a value for use with context.WithValue. It's used as
    41  // a pointer so it fits in an interface{} without allocation.
    42  type contextKey struct {
    43  	name string
    44  }
    45  
    46  func (k *contextKey) String() string { return "net/http context value " + k.name }
    47  
    48  // Given a string of the form "host", "host:port", or "[ipv6::address]:port",
    49  // return true if the string includes a port.
    50  func hasPort(s string) bool { return strings.LastIndex(s, ":") > strings.LastIndex(s, "]") }
    51  
    52  // removeEmptyPort strips the empty port in ":port" to ""
    53  // as mandated by RFC 3986 Section 6.2.3.
    54  func removeEmptyPort(host string) string {
    55  	if hasPort(host) {
    56  		return strings.TrimSuffix(host, ":")
    57  	}
    58  	return host
    59  }
    60  
    61  func isNotToken(r rune) bool {
    62  	return !httpguts.IsTokenRune(r)
    63  }
    64  
    65  // stringContainsCTLByte reports whether s contains any ASCII control character.
    66  func stringContainsCTLByte(s string) bool {
    67  	for i := 0; i < len(s); i++ {
    68  		b := s[i]
    69  		if b < ' ' || b == 0x7f {
    70  			return true
    71  		}
    72  	}
    73  	return false
    74  }
    75  
    76  func hexEscapeNonASCII(s string) string {
    77  	newLen := 0
    78  	for i := 0; i < len(s); i++ {
    79  		if s[i] >= utf8.RuneSelf {
    80  			newLen += 3
    81  		} else {
    82  			newLen++
    83  		}
    84  	}
    85  	if newLen == len(s) {
    86  		return s
    87  	}
    88  	b := make([]byte, 0, newLen)
    89  	var pos int
    90  	for i := 0; i < len(s); i++ {
    91  		if s[i] >= utf8.RuneSelf {
    92  			if pos < i {
    93  				b = append(b, s[pos:i]...)
    94  			}
    95  			b = append(b, '%')
    96  			b = strconv.AppendInt(b, int64(s[i]), 16)
    97  			pos = i + 1
    98  		}
    99  	}
   100  	if pos < len(s) {
   101  		b = append(b, s[pos:]...)
   102  	}
   103  	return string(b)
   104  }
   105  
   106  // NoBody is an [io.ReadCloser] with no bytes. Read always returns EOF
   107  // and Close always returns nil. It can be used in an outgoing client
   108  // request to explicitly signal that a request has zero bytes.
   109  // An alternative, however, is to simply set [Request.Body] to nil.
   110  var NoBody = noBody{}
   111  
   112  type noBody struct{}
   113  
   114  func (noBody) Read([]byte) (int, error)         { return 0, io.EOF }
   115  func (noBody) Close() error                     { return nil }
   116  func (noBody) WriteTo(io.Writer) (int64, error) { return 0, nil }
   117  
   118  var (
   119  	// verify that an io.Copy from NoBody won't require a buffer:
   120  	_ io.WriterTo   = NoBody
   121  	_ io.ReadCloser = NoBody
   122  )
   123  
   124  // PushOptions describes options for [Pusher.Push].
   125  type PushOptions struct {
   126  	// Method specifies the HTTP method for the promised request.
   127  	// If set, it must be "GET" or "HEAD". Empty means "GET".
   128  	Method string
   129  
   130  	// Header specifies additional promised request headers. This cannot
   131  	// include HTTP/2 pseudo header fields like ":path" and ":scheme",
   132  	// which will be added automatically.
   133  	Header Header
   134  }
   135  
   136  // Pusher is the interface implemented by ResponseWriters that support
   137  // HTTP/2 server push. For more background, see
   138  // https://tools.ietf.org/html/rfc7540#section-8.2.
   139  type Pusher interface {
   140  	// Push initiates an HTTP/2 server push. This constructs a synthetic
   141  	// request using the given target and options, serializes that request
   142  	// into a PUSH_PROMISE frame, then dispatches that request using the
   143  	// server's request handler. If opts is nil, default options are used.
   144  	//
   145  	// The target must either be an absolute path (like "/path") or an absolute
   146  	// URL that contains a valid host and the same scheme as the parent request.
   147  	// If the target is a path, it will inherit the scheme and host of the
   148  	// parent request.
   149  	//
   150  	// The HTTP/2 spec disallows recursive pushes and cross-authority pushes.
   151  	// Push may or may not detect these invalid pushes; however, invalid
   152  	// pushes will be detected and canceled by conforming clients.
   153  	//
   154  	// Handlers that wish to push URL X should call Push before sending any
   155  	// data that may trigger a request for URL X. This avoids a race where the
   156  	// client issues requests for X before receiving the PUSH_PROMISE for X.
   157  	//
   158  	// Push will run in a separate goroutine making the order of arrival
   159  	// non-deterministic. Any required synchronization needs to be implemented
   160  	// by the caller.
   161  	//
   162  	// Push returns ErrNotSupported if the client has disabled push or if push
   163  	// is not supported on the underlying connection.
   164  	Push(target string, opts *PushOptions) error
   165  }
   166
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