fd_windows.go

Documentation: net

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