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  	if err := fd.pfd.Init(fd.net, true); err != nil {
    57  		return err
    58  	}
    59  	switch fd.net {
    60  	case "udp", "udp4", "udp6":
    61  		// Disable reporting of PORT_UNREACHABLE errors.
    62  		// See https://go.dev/issue/5834.
    63  		ret := uint32(0)
    64  		flag := uint32(0)
    65  		size := uint32(unsafe.Sizeof(flag))
    66  		err := syscall.WSAIoctl(fd.pfd.Sysfd, syscall.SIO_UDP_CONNRESET, (*byte)(unsafe.Pointer(&flag)), size, nil, 0, &ret, nil, 0)
    67  		if err != nil {
    68  			return wrapSyscallError("wsaioctl", err)
    69  		}
    70  	}
    71  	return nil
    72  }
    73  
    74  // Always returns nil for connected peer address result.
    75  func (fd *netFD) connect(ctx context.Context, la, ra syscall.Sockaddr) (syscall.Sockaddr, error) {
    76  	// Do not need to call fd.writeLock here,
    77  	// because fd is not yet accessible to user,
    78  	// so no concurrent operations are possible.
    79  	if err := fd.init(); err != nil {
    80  		return nil, err
    81  	}
    82  
    83  	if ctx.Done() != nil {
    84  		// Propagate the Context's deadline and cancellation.
    85  		// If the context is already done, or if it has a nonzero deadline,
    86  		// ensure that that is applied before the call to ConnectEx begins
    87  		// so that we don't return spurious connections.
    88  		defer fd.pfd.SetWriteDeadline(noDeadline)
    89  
    90  		if ctx.Err() != nil {
    91  			fd.pfd.SetWriteDeadline(aLongTimeAgo)
    92  		} else {
    93  			if deadline, ok := ctx.Deadline(); ok && !deadline.IsZero() {
    94  				fd.pfd.SetWriteDeadline(deadline)
    95  			}
    96  
    97  			done := make(chan struct{})
    98  			stop := context.AfterFunc(ctx, func() {
    99  				// Force the runtime's poller to immediately give
   100  				// up waiting for writability.
   101  				fd.pfd.SetWriteDeadline(aLongTimeAgo)
   102  				close(done)
   103  			})
   104  			defer func() {
   105  				if !stop() {
   106  					// Wait for the call to SetWriteDeadline to complete so that we can
   107  					// reset the deadline if everything else succeeded.
   108  					<-done
   109  				}
   110  			}()
   111  		}
   112  	}
   113  
   114  	if !canUseConnectEx(fd.net) {
   115  		err := connectFunc(fd.pfd.Sysfd, ra)
   116  		return nil, os.NewSyscallError("connect", err)
   117  	}
   118  	// ConnectEx windows API requires an unconnected, previously bound socket.
   119  	if la == nil {
   120  		switch ra.(type) {
   121  		case *syscall.SockaddrInet4:
   122  			la = &syscall.SockaddrInet4{}
   123  		case *syscall.SockaddrInet6:
   124  			la = &syscall.SockaddrInet6{}
   125  		default:
   126  			panic("unexpected type in connect")
   127  		}
   128  		if err := syscall.Bind(fd.pfd.Sysfd, la); err != nil {
   129  			return nil, os.NewSyscallError("bind", err)
   130  		}
   131  	}
   132  
   133  	var isloopback bool
   134  	switch ra := ra.(type) {
   135  	case *syscall.SockaddrInet4:
   136  		isloopback = ra.Addr[0] == 127
   137  	case *syscall.SockaddrInet6:
   138  		isloopback = ra.Addr == [16]byte(IPv6loopback)
   139  	default:
   140  		panic("unexpected type in connect")
   141  	}
   142  	if isloopback {
   143  		// This makes ConnectEx() fails faster if the target port on the localhost
   144  		// is not reachable, instead of waiting for 2s.
   145  		params := windows.TCP_INITIAL_RTO_PARAMETERS{
   146  			Rtt:                   windows.TCP_INITIAL_RTO_UNSPECIFIED_RTT, // use the default or overridden by the Administrator
   147  			MaxSynRetransmissions: 1,                                       // minimum possible value before Windows 10.0.16299
   148  		}
   149  		if windows.SupportTCPInitialRTONoSYNRetransmissions() {
   150  			// In Windows 10.0.16299 TCP_INITIAL_RTO_NO_SYN_RETRANSMISSIONS makes ConnectEx() fails instantly.
   151  			params.MaxSynRetransmissions = windows.TCP_INITIAL_RTO_NO_SYN_RETRANSMISSIONS
   152  		}
   153  		var out uint32
   154  		// Don't abort the connection if WSAIoctl fails, as it is only an optimization.
   155  		// If it fails reliably, we expect TestDialClosedPortFailFast to detect it.
   156  		_ = fd.pfd.WSAIoctl(windows.SIO_TCP_INITIAL_RTO, (*byte)(unsafe.Pointer(&params)), uint32(unsafe.Sizeof(params)), nil, 0, &out, nil, 0)
   157  	}
   158  
   159  	// Call ConnectEx API.
   160  	if err := fd.pfd.ConnectEx(ra); err != nil {
   161  		select {
   162  		case <-ctx.Done():
   163  			return nil, mapErr(ctx.Err())
   164  		default:
   165  			if _, ok := err.(syscall.Errno); ok {
   166  				err = os.NewSyscallError("connectex", err)
   167  			}
   168  			return nil, err
   169  		}
   170  	}
   171  	// Refresh socket properties.
   172  	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))))
   173  }
   174  
   175  func (c *conn) writeBuffers(v *Buffers) (int64, error) {
   176  	if !c.ok() {
   177  		return 0, syscall.EINVAL
   178  	}
   179  	n, err := c.fd.writeBuffers(v)
   180  	if err != nil {
   181  		return n, &OpError{Op: "wsasend", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
   182  	}
   183  	return n, nil
   184  }
   185  
   186  func (fd *netFD) writeBuffers(buf *Buffers) (int64, error) {
   187  	n, err := fd.pfd.Writev((*[][]byte)(buf))
   188  	runtime.KeepAlive(fd)
   189  	return n, wrapSyscallError("wsasend", err)
   190  }
   191  
   192  func (fd *netFD) accept() (*netFD, error) {
   193  	s, rawsa, rsan, errcall, err := fd.pfd.Accept(func() (syscall.Handle, error) {
   194  		return sysSocket(fd.family, fd.sotype, 0)
   195  	})
   196  
   197  	if err != nil {
   198  		if errcall != "" {
   199  			err = wrapSyscallError(errcall, err)
   200  		}
   201  		return nil, err
   202  	}
   203  
   204  	// Associate our new socket with IOCP.
   205  	netfd, err := newFD(s, fd.family, fd.sotype, fd.net)
   206  	if err != nil {
   207  		poll.CloseFunc(s)
   208  		return nil, err
   209  	}
   210  	if err := netfd.init(); err != nil {
   211  		fd.Close()
   212  		return nil, err
   213  	}
   214  
   215  	// Get local and peer addr out of AcceptEx buffer.
   216  	var lrsa, rrsa *syscall.RawSockaddrAny
   217  	var llen, rlen int32
   218  	syscall.GetAcceptExSockaddrs((*byte)(unsafe.Pointer(&rawsa[0])),
   219  		0, rsan, rsan, &lrsa, &llen, &rrsa, &rlen)
   220  	lsa, _ := lrsa.Sockaddr()
   221  	rsa, _ := rrsa.Sockaddr()
   222  
   223  	netfd.setAddr(netfd.addrFunc()(lsa), netfd.addrFunc()(rsa))
   224  	return netfd, nil
   225  }
   226  
   227  // Unimplemented functions.
   228  
   229  func (fd *netFD) dup() (*os.File, error) {
   230  	// TODO: Implement this, perhaps using internal/poll.DupCloseOnExec.
   231  	return nil, syscall.EWINDOWS
   232  }
   233
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