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, keepAlive time.Duration, keepAliveHook func(time.Duration)) *TCPConn {
   221  	setNoDelay(fd, true)
   222  	if keepAlive == 0 {
   223  		keepAlive = defaultTCPKeepAlive
   224  	}
   225  	if keepAlive > 0 {
   226  		setKeepAlive(fd, true)
   227  		setKeepAlivePeriod(fd, keepAlive)
   228  		if keepAliveHook != nil {
   229  			keepAliveHook(keepAlive)
   230  		}
   231  	}
   232  	return &TCPConn{conn{fd}}
   233  }
   234  
   235  // DialTCP acts like Dial for TCP networks.
   236  //
   237  // The network must be a TCP network name; see func Dial for details.
   238  //
   239  // If laddr is nil, a local address is automatically chosen.
   240  // If the IP field of raddr is nil or an unspecified IP address, the
   241  // local system is assumed.
   242  func DialTCP(network string, laddr, raddr *TCPAddr) (*TCPConn, error) {
   243  	switch network {
   244  	case "tcp", "tcp4", "tcp6":
   245  	default:
   246  		return nil, &OpError{Op: "dial", Net: network, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: UnknownNetworkError(network)}
   247  	}
   248  	if raddr == nil {
   249  		return nil, &OpError{Op: "dial", Net: network, Source: laddr.opAddr(), Addr: nil, Err: errMissingAddress}
   250  	}
   251  	sd := &sysDialer{network: network, address: raddr.String()}
   252  	c, err := sd.dialTCP(context.Background(), laddr, raddr)
   253  	if err != nil {
   254  		return nil, &OpError{Op: "dial", Net: network, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: err}
   255  	}
   256  	return c, nil
   257  }
   258  
   259  // TCPListener is a TCP network listener. Clients should typically
   260  // use variables of type Listener instead of assuming TCP.
   261  type TCPListener struct {
   262  	fd *netFD
   263  	lc ListenConfig
   264  }
   265  
   266  // SyscallConn returns a raw network connection.
   267  // This implements the syscall.Conn interface.
   268  //
   269  // The returned RawConn only supports calling Control. Read and
   270  // Write return an error.
   271  func (l *TCPListener) SyscallConn() (syscall.RawConn, error) {
   272  	if !l.ok() {
   273  		return nil, syscall.EINVAL
   274  	}
   275  	return newRawListener(l.fd)
   276  }
   277  
   278  // AcceptTCP accepts the next incoming call and returns the new
   279  // connection.
   280  func (l *TCPListener) AcceptTCP() (*TCPConn, error) {
   281  	if !l.ok() {
   282  		return nil, syscall.EINVAL
   283  	}
   284  	c, err := l.accept()
   285  	if err != nil {
   286  		return nil, &OpError{Op: "accept", Net: l.fd.net, Source: nil, Addr: l.fd.laddr, Err: err}
   287  	}
   288  	return c, nil
   289  }
   290  
   291  // Accept implements the Accept method in the Listener interface; it
   292  // waits for the next call and returns a generic Conn.
   293  func (l *TCPListener) Accept() (Conn, error) {
   294  	if !l.ok() {
   295  		return nil, syscall.EINVAL
   296  	}
   297  	c, err := l.accept()
   298  	if err != nil {
   299  		return nil, &OpError{Op: "accept", Net: l.fd.net, Source: nil, Addr: l.fd.laddr, Err: err}
   300  	}
   301  	return c, nil
   302  }
   303  
   304  // Close stops listening on the TCP address.
   305  // Already Accepted connections are not closed.
   306  func (l *TCPListener) Close() error {
   307  	if !l.ok() {
   308  		return syscall.EINVAL
   309  	}
   310  	if err := l.close(); err != nil {
   311  		return &OpError{Op: "close", Net: l.fd.net, Source: nil, Addr: l.fd.laddr, Err: err}
   312  	}
   313  	return nil
   314  }
   315  
   316  // Addr returns the listener's network address, a *TCPAddr.
   317  // The Addr returned is shared by all invocations of Addr, so
   318  // do not modify it.
   319  func (l *TCPListener) Addr() Addr { return l.fd.laddr }
   320  
   321  // SetDeadline sets the deadline associated with the listener.
   322  // A zero time value disables the deadline.
   323  func (l *TCPListener) SetDeadline(t time.Time) error {
   324  	if !l.ok() {
   325  		return syscall.EINVAL
   326  	}
   327  	if err := l.fd.pfd.SetDeadline(t); err != nil {
   328  		return &OpError{Op: "set", Net: l.fd.net, Source: nil, Addr: l.fd.laddr, Err: err}
   329  	}
   330  	return nil
   331  }
   332  
   333  // File returns a copy of the underlying os.File.
   334  // It is the caller's responsibility to close f when finished.
   335  // Closing l does not affect f, and closing f does not affect l.
   336  //
   337  // The returned os.File's file descriptor is different from the
   338  // connection's. Attempting to change properties of the original
   339  // using this duplicate may or may not have the desired effect.
   340  func (l *TCPListener) File() (f *os.File, err error) {
   341  	if !l.ok() {
   342  		return nil, syscall.EINVAL
   343  	}
   344  	f, err = l.file()
   345  	if err != nil {
   346  		return nil, &OpError{Op: "file", Net: l.fd.net, Source: nil, Addr: l.fd.laddr, Err: err}
   347  	}
   348  	return
   349  }
   350  
   351  // ListenTCP acts like Listen for TCP networks.
   352  //
   353  // The network must be a TCP network name; see func Dial for details.
   354  //
   355  // If the IP field of laddr is nil or an unspecified IP address,
   356  // ListenTCP listens on all available unicast and anycast IP addresses
   357  // of the local system.
   358  // If the Port field of laddr is 0, a port number is automatically
   359  // chosen.
   360  func ListenTCP(network string, laddr *TCPAddr) (*TCPListener, error) {
   361  	switch network {
   362  	case "tcp", "tcp4", "tcp6":
   363  	default:
   364  		return nil, &OpError{Op: "listen", Net: network, Source: nil, Addr: laddr.opAddr(), Err: UnknownNetworkError(network)}
   365  	}
   366  	if laddr == nil {
   367  		laddr = &TCPAddr{}
   368  	}
   369  	sl := &sysListener{network: network, address: laddr.String()}
   370  	ln, err := sl.listenTCP(context.Background(), laddr)
   371  	if err != nil {
   372  		return nil, &OpError{Op: "listen", Net: network, Source: nil, Addr: laddr.opAddr(), Err: err}
   373  	}
   374  	return ln, nil
   375  }
   376  
   377  // roundDurationUp rounds d to the next multiple of to.
   378  func roundDurationUp(d time.Duration, to time.Duration) time.Duration {
   379  	return (d + to - 1) / to
   380  }
   381
View as plain text