Source file src/net/tcpsock.go

     1  // Copyright 2009 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/itoa"
    10  	"io"
    11  	"net/netip"
    12  	"os"
    13  	"syscall"
    14  	"time"
    15  )
    16  
    17  // BUG(mikio): On JS and Windows, the File method of TCPConn and
    18  // TCPListener is not implemented.
    19  
    20  // TCPAddr represents the address of a TCP end point.
    21  type TCPAddr struct {
    22  	IP   IP
    23  	Port int
    24  	Zone string // IPv6 scoped addressing zone
    25  }
    26  
    27  // AddrPort returns the TCPAddr a as a netip.AddrPort.
    28  //
    29  // If a.Port does not fit in a uint16, it's silently truncated.
    30  //
    31  // If a is nil, a zero value is returned.
    32  func (a *TCPAddr) AddrPort() netip.AddrPort {
    33  	if a == nil {
    34  		return netip.AddrPort{}
    35  	}
    36  	na, _ := netip.AddrFromSlice(a.IP)
    37  	na = na.WithZone(a.Zone)
    38  	return netip.AddrPortFrom(na, uint16(a.Port))
    39  }
    40  
    41  // Network returns the address's network name, "tcp".
    42  func (a *TCPAddr) Network() string { return "tcp" }
    43  
    44  func (a *TCPAddr) String() string {
    45  	if a == nil {
    46  		return "<nil>"
    47  	}
    48  	ip := ipEmptyString(a.IP)
    49  	if a.Zone != "" {
    50  		return JoinHostPort(ip+"%"+a.Zone, itoa.Itoa(a.Port))
    51  	}
    52  	return JoinHostPort(ip, itoa.Itoa(a.Port))
    53  }
    54  
    55  func (a *TCPAddr) isWildcard() bool {
    56  	if a == nil || a.IP == nil {
    57  		return true
    58  	}
    59  	return a.IP.IsUnspecified()
    60  }
    61  
    62  func (a *TCPAddr) opAddr() Addr {
    63  	if a == nil {
    64  		return nil
    65  	}
    66  	return a
    67  }
    68  
    69  // ResolveTCPAddr returns an address of TCP end point.
    70  //
    71  // The network must be a TCP network name.
    72  //
    73  // If the host in the address parameter is not a literal IP address or
    74  // the port is not a literal port number, ResolveTCPAddr resolves the
    75  // address to an address of TCP end point.
    76  // Otherwise, it parses the address as a pair of literal IP address
    77  // and port number.
    78  // The address parameter can use a host name, but this is not
    79  // recommended, because it will return at most one of the host name's
    80  // IP addresses.
    81  //
    82  // See func Dial for a description of the network and address
    83  // parameters.
    84  func ResolveTCPAddr(network, address string) (*TCPAddr, error) {
    85  	switch network {
    86  	case "tcp", "tcp4", "tcp6":
    87  	case "": // a hint wildcard for Go 1.0 undocumented behavior
    88  		network = "tcp"
    89  	default:
    90  		return nil, UnknownNetworkError(network)
    91  	}
    92  	addrs, err := DefaultResolver.internetAddrList(context.Background(), network, address)
    93  	if err != nil {
    94  		return nil, err
    95  	}
    96  	return addrs.forResolve(network, address).(*TCPAddr), nil
    97  }
    98  
    99  // TCPAddrFromAddrPort returns addr as a TCPAddr. If addr.IsValid() is false,
   100  // then the returned TCPAddr will contain a nil IP field, indicating an
   101  // address family-agnostic unspecified address.
   102  func TCPAddrFromAddrPort(addr netip.AddrPort) *TCPAddr {
   103  	return &TCPAddr{
   104  		IP:   addr.Addr().AsSlice(),
   105  		Zone: addr.Addr().Zone(),
   106  		Port: int(addr.Port()),
   107  	}
   108  }
   109  
   110  // TCPConn is an implementation of the Conn interface for TCP network
   111  // connections.
   112  type TCPConn struct {
   113  	conn
   114  }
   115  
   116  // SyscallConn returns a raw network connection.
   117  // This implements the syscall.Conn interface.
   118  func (c *TCPConn) SyscallConn() (syscall.RawConn, error) {
   119  	if !c.ok() {
   120  		return nil, syscall.EINVAL
   121  	}
   122  	return newRawConn(c.fd)
   123  }
   124  
   125  // ReadFrom implements the io.ReaderFrom ReadFrom method.
   126  func (c *TCPConn) ReadFrom(r io.Reader) (int64, error) {
   127  	if !c.ok() {
   128  		return 0, syscall.EINVAL
   129  	}
   130  	n, err := c.readFrom(r)
   131  	if err != nil && err != io.EOF {
   132  		err = &OpError{Op: "readfrom", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
   133  	}
   134  	return n, err
   135  }
   136  
   137  // CloseRead shuts down the reading side of the TCP connection.
   138  // Most callers should just use Close.
   139  func (c *TCPConn) CloseRead() error {
   140  	if !c.ok() {
   141  		return syscall.EINVAL
   142  	}
   143  	if err := c.fd.closeRead(); err != nil {
   144  		return &OpError{Op: "close", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
   145  	}
   146  	return nil
   147  }
   148  
   149  // CloseWrite shuts down the writing side of the TCP connection.
   150  // Most callers should just use Close.
   151  func (c *TCPConn) CloseWrite() error {
   152  	if !c.ok() {
   153  		return syscall.EINVAL
   154  	}
   155  	if err := c.fd.closeWrite(); err != nil {
   156  		return &OpError{Op: "close", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
   157  	}
   158  	return nil
   159  }
   160  
   161  // SetLinger sets the behavior of Close on a connection which still
   162  // has data waiting to be sent or to be acknowledged.
   163  //
   164  // If sec < 0 (the default), the operating system finishes sending the
   165  // data in the background.
   166  //
   167  // If sec == 0, the operating system discards any unsent or
   168  // unacknowledged data.
   169  //
   170  // If sec > 0, the data is sent in the background as with sec < 0. On
   171  // some operating systems after sec seconds have elapsed any remaining
   172  // unsent data may be discarded.
   173  func (c *TCPConn) SetLinger(sec int) error {
   174  	if !c.ok() {
   175  		return syscall.EINVAL
   176  	}
   177  	if err := setLinger(c.fd, sec); err != nil {
   178  		return &OpError{Op: "set", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
   179  	}
   180  	return nil
   181  }
   182  
   183  // SetKeepAlive sets whether the operating system should send
   184  // keep-alive messages on the connection.
   185  func (c *TCPConn) SetKeepAlive(keepalive bool) error {
   186  	if !c.ok() {
   187  		return syscall.EINVAL
   188  	}
   189  	if err := setKeepAlive(c.fd, keepalive); err != nil {
   190  		return &OpError{Op: "set", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
   191  	}
   192  	return nil
   193  }
   194  
   195  // SetKeepAlivePeriod sets period between keep-alives.
   196  func (c *TCPConn) SetKeepAlivePeriod(d time.Duration) error {
   197  	if !c.ok() {
   198  		return syscall.EINVAL
   199  	}
   200  	if err := setKeepAlivePeriod(c.fd, d); err != nil {
   201  		return &OpError{Op: "set", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
   202  	}
   203  	return nil
   204  }
   205  
   206  // SetNoDelay controls whether the operating system should delay
   207  // packet transmission in hopes of sending fewer packets (Nagle's
   208  // algorithm).  The default is true (no delay), meaning that data is
   209  // sent as soon as possible after a Write.
   210  func (c *TCPConn) SetNoDelay(noDelay bool) error {
   211  	if !c.ok() {
   212  		return syscall.EINVAL
   213  	}
   214  	if err := setNoDelay(c.fd, noDelay); err != nil {
   215  		return &OpError{Op: "set", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
   216  	}
   217  	return nil
   218  }
   219  
   220  func newTCPConn(fd *netFD) *TCPConn {
   221  	c := &TCPConn{conn{fd}}
   222  	setNoDelay(c.fd, true)
   223  	return c
   224  }
   225  
   226  // DialTCP acts like Dial for TCP networks.
   227  //
   228  // The network must be a TCP network name; see func Dial for details.
   229  //
   230  // If laddr is nil, a local address is automatically chosen.
   231  // If the IP field of raddr is nil or an unspecified IP address, the
   232  // local system is assumed.
   233  func DialTCP(network string, laddr, raddr *TCPAddr) (*TCPConn, error) {
   234  	switch network {
   235  	case "tcp", "tcp4", "tcp6":
   236  	default:
   237  		return nil, &OpError{Op: "dial", Net: network, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: UnknownNetworkError(network)}
   238  	}
   239  	if raddr == nil {
   240  		return nil, &OpError{Op: "dial", Net: network, Source: laddr.opAddr(), Addr: nil, Err: errMissingAddress}
   241  	}
   242  	sd := &sysDialer{network: network, address: raddr.String()}
   243  	c, err := sd.dialTCP(context.Background(), laddr, raddr)
   244  	if err != nil {
   245  		return nil, &OpError{Op: "dial", Net: network, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: err}
   246  	}
   247  	return c, nil
   248  }
   249  
   250  // TCPListener is a TCP network listener. Clients should typically
   251  // use variables of type Listener instead of assuming TCP.
   252  type TCPListener struct {
   253  	fd *netFD
   254  	lc ListenConfig
   255  }
   256  
   257  // SyscallConn returns a raw network connection.
   258  // This implements the syscall.Conn interface.
   259  //
   260  // The returned RawConn only supports calling Control. Read and
   261  // Write return an error.
   262  func (l *TCPListener) SyscallConn() (syscall.RawConn, error) {
   263  	if !l.ok() {
   264  		return nil, syscall.EINVAL
   265  	}
   266  	return newRawListener(l.fd)
   267  }
   268  
   269  // AcceptTCP accepts the next incoming call and returns the new
   270  // connection.
   271  func (l *TCPListener) AcceptTCP() (*TCPConn, error) {
   272  	if !l.ok() {
   273  		return nil, syscall.EINVAL
   274  	}
   275  	c, err := l.accept()
   276  	if err != nil {
   277  		return nil, &OpError{Op: "accept", Net: l.fd.net, Source: nil, Addr: l.fd.laddr, Err: err}
   278  	}
   279  	return c, nil
   280  }
   281  
   282  // Accept implements the Accept method in the Listener interface; it
   283  // waits for the next call and returns a generic Conn.
   284  func (l *TCPListener) Accept() (Conn, error) {
   285  	if !l.ok() {
   286  		return nil, syscall.EINVAL
   287  	}
   288  	c, err := l.accept()
   289  	if err != nil {
   290  		return nil, &OpError{Op: "accept", Net: l.fd.net, Source: nil, Addr: l.fd.laddr, Err: err}
   291  	}
   292  	return c, nil
   293  }
   294  
   295  // Close stops listening on the TCP address.
   296  // Already Accepted connections are not closed.
   297  func (l *TCPListener) Close() error {
   298  	if !l.ok() {
   299  		return syscall.EINVAL
   300  	}
   301  	if err := l.close(); err != nil {
   302  		return &OpError{Op: "close", Net: l.fd.net, Source: nil, Addr: l.fd.laddr, Err: err}
   303  	}
   304  	return nil
   305  }
   306  
   307  // Addr returns the listener's network address, a *TCPAddr.
   308  // The Addr returned is shared by all invocations of Addr, so
   309  // do not modify it.
   310  func (l *TCPListener) Addr() Addr { return l.fd.laddr }
   311  
   312  // SetDeadline sets the deadline associated with the listener.
   313  // A zero time value disables the deadline.
   314  func (l *TCPListener) SetDeadline(t time.Time) error {
   315  	if !l.ok() {
   316  		return syscall.EINVAL
   317  	}
   318  	if err := l.fd.pfd.SetDeadline(t); err != nil {
   319  		return &OpError{Op: "set", Net: l.fd.net, Source: nil, Addr: l.fd.laddr, Err: err}
   320  	}
   321  	return nil
   322  }
   323  
   324  // File returns a copy of the underlying os.File.
   325  // It is the caller's responsibility to close f when finished.
   326  // Closing l does not affect f, and closing f does not affect l.
   327  //
   328  // The returned os.File's file descriptor is different from the
   329  // connection's. Attempting to change properties of the original
   330  // using this duplicate may or may not have the desired effect.
   331  func (l *TCPListener) File() (f *os.File, err error) {
   332  	if !l.ok() {
   333  		return nil, syscall.EINVAL
   334  	}
   335  	f, err = l.file()
   336  	if err != nil {
   337  		return nil, &OpError{Op: "file", Net: l.fd.net, Source: nil, Addr: l.fd.laddr, Err: err}
   338  	}
   339  	return
   340  }
   341  
   342  // ListenTCP acts like Listen for TCP networks.
   343  //
   344  // The network must be a TCP network name; see func Dial for details.
   345  //
   346  // If the IP field of laddr is nil or an unspecified IP address,
   347  // ListenTCP listens on all available unicast and anycast IP addresses
   348  // of the local system.
   349  // If the Port field of laddr is 0, a port number is automatically
   350  // chosen.
   351  func ListenTCP(network string, laddr *TCPAddr) (*TCPListener, error) {
   352  	switch network {
   353  	case "tcp", "tcp4", "tcp6":
   354  	default:
   355  		return nil, &OpError{Op: "listen", Net: network, Source: nil, Addr: laddr.opAddr(), Err: UnknownNetworkError(network)}
   356  	}
   357  	if laddr == nil {
   358  		laddr = &TCPAddr{}
   359  	}
   360  	sl := &sysListener{network: network, address: laddr.String()}
   361  	ln, err := sl.listenTCP(context.Background(), laddr)
   362  	if err != nil {
   363  		return nil, &OpError{Op: "listen", Net: network, Source: nil, Addr: laddr.opAddr(), Err: err}
   364  	}
   365  	return ln, nil
   366  }
   367  
   368  // roundDurationUp rounds d to the next multiple of to.
   369  func roundDurationUp(d time.Duration, to time.Duration) time.Duration {
   370  	return (d + to - 1) / to
   371  }
   372  

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