fd_windows.go

     1  // Copyright 2010 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  package net
     6  
     7  import (
     8  	"context"
     9  	"internal/poll"
    10  	"internal/syscall/windows"
    11  	"os"
    12  	"runtime"
    13  	"syscall"
    14  	"unsafe"
    15  )
    16  
    17  const (
    18  	readSyscallName     = "wsarecv"
    19  	readFromSyscallName = "wsarecvfrom"
    20  	readMsgSyscallName  = "wsarecvmsg"
    21  	writeSyscallName    = "wsasend"
    22  	writeToSyscallName  = "wsasendto"
    23  	writeMsgSyscallName = "wsasendmsg"
    24  )
    25  
    26  func init() {
    27  	poll.InitWSA()
    28  }
    29  
    30  // canUseConnectEx reports whether we can use the ConnectEx Windows API call
    31  // for the given network type.
    32  func canUseConnectEx(net string) bool {
    33  	switch net {
    34  	case "tcp", "tcp4", "tcp6":
    35  		return true
    36  	}
    37  	// ConnectEx windows API does not support connectionless sockets.
    38  	return false
    39  }
    40  
    41  func newFD(sysfd syscall.Handle, family, sotype int, net string) (*netFD, error) {
    42  	ret := &netFD{
    43  		pfd: poll.FD{
    44  			Sysfd:         sysfd,
    45  			IsStream:      sotype == syscall.SOCK_STREAM,
    46  			ZeroReadIsEOF: sotype != syscall.SOCK_DGRAM && sotype != syscall.SOCK_RAW,
    47  		},
    48  		family: family,
    49  		sotype: sotype,
    50  		net:    net,
    51  	}
    52  	return ret, nil
    53  }
    54  
    55  func (fd *netFD) init() error {
    56  	errcall, err := fd.pfd.Init(fd.net, true)
    57  	if errcall != "" {
    58  		err = wrapSyscallError(errcall, err)
    59  	}
    60  	return err
    61  }
    62  
    63  // Always returns nil for connected peer address result.
    64  func (fd *netFD) connect(ctx context.Context, la, ra syscall.Sockaddr) (syscall.Sockaddr, error) {
    65  	// Do not need to call fd.writeLock here,
    66  	// because fd is not yet accessible to user,
    67  	// so no concurrent operations are possible.
    68  	if err := fd.init(); err != nil {
    69  		return nil, err
    70  	}
    71  
    72  	if ctx.Done() != nil {
    73  		// Propagate the Context's deadline and cancellation.
    74  		// If the context is already done, or if it has a nonzero deadline,
    75  		// ensure that that is applied before the call to ConnectEx begins
    76  		// so that we don't return spurious connections.
    77  		defer fd.pfd.SetWriteDeadline(noDeadline)
    78  
    79  		if ctx.Err() != nil {
    80  			fd.pfd.SetWriteDeadline(aLongTimeAgo)
    81  		} else {
    82  			if deadline, ok := ctx.Deadline(); ok && !deadline.IsZero() {
    83  				fd.pfd.SetWriteDeadline(deadline)
    84  			}
    85  
    86  			done := make(chan struct{})
    87  			stop := context.AfterFunc(ctx, func() {
    88  				// Force the runtime's poller to immediately give
    89  				// up waiting for writability.
    90  				fd.pfd.SetWriteDeadline(aLongTimeAgo)
    91  				close(done)
    92  			})
    93  			defer func() {
    94  				if !stop() {
    95  					// Wait for the call to SetWriteDeadline to complete so that we can
    96  					// reset the deadline if everything else succeeded.
    97  					<-done
    98  				}
    99  			}()
   100  		}
   101  	}
   102  
   103  	if !canUseConnectEx(fd.net) {
   104  		err := connectFunc(fd.pfd.Sysfd, ra)
   105  		return nil, os.NewSyscallError("connect", err)
   106  	}
   107  	// ConnectEx windows API requires an unconnected, previously bound socket.
   108  	if la == nil {
   109  		switch ra.(type) {
   110  		case *syscall.SockaddrInet4:
   111  			la = &syscall.SockaddrInet4{}
   112  		case *syscall.SockaddrInet6:
   113  			la = &syscall.SockaddrInet6{}
   114  		default:
   115  			panic("unexpected type in connect")
   116  		}
   117  		if err := syscall.Bind(fd.pfd.Sysfd, la); err != nil {
   118  			return nil, os.NewSyscallError("bind", err)
   119  		}
   120  	}
   121  
   122  	var isloopback bool
   123  	switch ra := ra.(type) {
   124  	case *syscall.SockaddrInet4:
   125  		isloopback = ra.Addr[0] == 127
   126  	case *syscall.SockaddrInet6:
   127  		isloopback = ra.Addr == [16]byte(IPv6loopback)
   128  	default:
   129  		panic("unexpected type in connect")
   130  	}
   131  	if isloopback {
   132  		// This makes ConnectEx() fails faster if the target port on the localhost
   133  		// is not reachable, instead of waiting for 2s.
   134  		params := windows.TCP_INITIAL_RTO_PARAMETERS{
   135  			Rtt:                   windows.TCP_INITIAL_RTO_UNSPECIFIED_RTT, // use the default or overridden by the Administrator
   136  			MaxSynRetransmissions: 1,                                       // minimum possible value before Windows 10.0.16299
   137  		}
   138  		if windows.SupportTCPInitialRTONoSYNRetransmissions() {
   139  			// In Windows 10.0.16299 TCP_INITIAL_RTO_NO_SYN_RETRANSMISSIONS makes ConnectEx() fails instantly.
   140  			params.MaxSynRetransmissions = windows.TCP_INITIAL_RTO_NO_SYN_RETRANSMISSIONS
   141  		}
   142  		var out uint32
   143  		// Don't abort the connection if WSAIoctl fails, as it is only an optimization.
   144  		// If it fails reliably, we expect TestDialClosedPortFailFast to detect it.
   145  		_ = fd.pfd.WSAIoctl(windows.SIO_TCP_INITIAL_RTO, (*byte)(unsafe.Pointer(&params)), uint32(unsafe.Sizeof(params)), nil, 0, &out, nil, 0)
   146  	}
   147  
   148  	// Call ConnectEx API.
   149  	if err := fd.pfd.ConnectEx(ra); err != nil {
   150  		select {
   151  		case <-ctx.Done():
   152  			return nil, mapErr(ctx.Err())
   153  		default:
   154  			if _, ok := err.(syscall.Errno); ok {
   155  				err = os.NewSyscallError("connectex", err)
   156  			}
   157  			return nil, err
   158  		}
   159  	}
   160  	// Refresh socket properties.
   161  	return nil, os.NewSyscallError("setsockopt", syscall.Setsockopt(fd.pfd.Sysfd, syscall.SOL_SOCKET, syscall.SO_UPDATE_CONNECT_CONTEXT, (*byte)(unsafe.Pointer(&fd.pfd.Sysfd)), int32(unsafe.Sizeof(fd.pfd.Sysfd))))
   162  }
   163  
   164  func (c *conn) writeBuffers(v *Buffers) (int64, error) {
   165  	if !c.ok() {
   166  		return 0, syscall.EINVAL
   167  	}
   168  	n, err := c.fd.writeBuffers(v)
   169  	if err != nil {
   170  		return n, &OpError{Op: "wsasend", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
   171  	}
   172  	return n, nil
   173  }
   174  
   175  func (fd *netFD) writeBuffers(buf *Buffers) (int64, error) {
   176  	n, err := fd.pfd.Writev((*[][]byte)(buf))
   177  	runtime.KeepAlive(fd)
   178  	return n, wrapSyscallError("wsasend", err)
   179  }
   180  
   181  func (fd *netFD) accept() (*netFD, error) {
   182  	s, rawsa, rsan, errcall, err := fd.pfd.Accept(func() (syscall.Handle, error) {
   183  		return sysSocket(fd.family, fd.sotype, 0)
   184  	})
   185  
   186  	if err != nil {
   187  		if errcall != "" {
   188  			err = wrapSyscallError(errcall, err)
   189  		}
   190  		return nil, err
   191  	}
   192  
   193  	// Associate our new socket with IOCP.
   194  	netfd, err := newFD(s, fd.family, fd.sotype, fd.net)
   195  	if err != nil {
   196  		poll.CloseFunc(s)
   197  		return nil, err
   198  	}
   199  	if err := netfd.init(); err != nil {
   200  		fd.Close()
   201  		return nil, err
   202  	}
   203  
   204  	// Get local and peer addr out of AcceptEx buffer.
   205  	var lrsa, rrsa *syscall.RawSockaddrAny
   206  	var llen, rlen int32
   207  	syscall.GetAcceptExSockaddrs((*byte)(unsafe.Pointer(&rawsa[0])),
   208  		0, rsan, rsan, &lrsa, &llen, &rrsa, &rlen)
   209  	lsa, _ := lrsa.Sockaddr()
   210  	rsa, _ := rrsa.Sockaddr()
   211  
   212  	netfd.setAddr(netfd.addrFunc()(lsa), netfd.addrFunc()(rsa))
   213  	return netfd, nil
   214  }
   215  
   216  // Unimplemented functions.
   217  
   218  func (fd *netFD) dup() (*os.File, error) {
   219  	// TODO: Implement this, perhaps using internal/poll.DupCloseOnExec.
   220  	return nil, syscall.EWINDOWS
   221  }
   222
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