github.com/activestate/go@v0.0.0-20170614201249-0b81c023a722/src/net/tcpsock.go (about)

     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  	"io"
    10  	"os"
    11  	"syscall"
    12  	"time"
    13  )
    14  
    15  // BUG(mikio): On Windows, the File method of TCPListener is not
    16  // implemented.
    17  
    18  // TCPAddr represents the address of a TCP end point.
    19  type TCPAddr struct {
    20  	IP   IP
    21  	Port int
    22  	Zone string // IPv6 scoped addressing zone
    23  }
    24  
    25  // Network returns the address's network name, "tcp".
    26  func (a *TCPAddr) Network() string { return "tcp" }
    27  
    28  func (a *TCPAddr) String() string {
    29  	if a == nil {
    30  		return "<nil>"
    31  	}
    32  	ip := ipEmptyString(a.IP)
    33  	if a.Zone != "" {
    34  		return JoinHostPort(ip+"%"+a.Zone, itoa(a.Port))
    35  	}
    36  	return JoinHostPort(ip, itoa(a.Port))
    37  }
    38  
    39  func (a *TCPAddr) isWildcard() bool {
    40  	if a == nil || a.IP == nil {
    41  		return true
    42  	}
    43  	return a.IP.IsUnspecified()
    44  }
    45  
    46  func (a *TCPAddr) opAddr() Addr {
    47  	if a == nil {
    48  		return nil
    49  	}
    50  	return a
    51  }
    52  
    53  // ResolveTCPAddr parses addr as a TCP address of the form "host:port"
    54  // or "[ipv6-host%zone]:port" and resolves a pair of domain name and
    55  // port name on the network net, which must be "tcp", "tcp4" or
    56  // "tcp6".  A literal address or host name for IPv6 must be enclosed
    57  // in square brackets, as in "[::1]:80", "[ipv6-host]:http" or
    58  // "[ipv6-host%zone]:80".
    59  //
    60  // Resolving a hostname is not recommended because this returns at most
    61  // one of its IP addresses.
    62  func ResolveTCPAddr(net, addr string) (*TCPAddr, error) {
    63  	switch net {
    64  	case "tcp", "tcp4", "tcp6":
    65  	case "": // a hint wildcard for Go 1.0 undocumented behavior
    66  		net = "tcp"
    67  	default:
    68  		return nil, UnknownNetworkError(net)
    69  	}
    70  	addrs, err := DefaultResolver.internetAddrList(context.Background(), net, addr)
    71  	if err != nil {
    72  		return nil, err
    73  	}
    74  	return addrs.first(isIPv4).(*TCPAddr), nil
    75  }
    76  
    77  // TCPConn is an implementation of the Conn interface for TCP network
    78  // connections.
    79  type TCPConn struct {
    80  	conn
    81  }
    82  
    83  // SyscallConn returns a raw network connection.
    84  // This implements the syscall.Conn interface.
    85  func (c *TCPConn) SyscallConn() (syscall.RawConn, error) {
    86  	if !c.ok() {
    87  		return nil, syscall.EINVAL
    88  	}
    89  	return newRawConn(c.fd)
    90  }
    91  
    92  // ReadFrom implements the io.ReaderFrom ReadFrom method.
    93  func (c *TCPConn) ReadFrom(r io.Reader) (int64, error) {
    94  	if !c.ok() {
    95  		return 0, syscall.EINVAL
    96  	}
    97  	n, err := c.readFrom(r)
    98  	if err != nil && err != io.EOF {
    99  		err = &OpError{Op: "readfrom", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
   100  	}
   101  	return n, err
   102  }
   103  
   104  // CloseRead shuts down the reading side of the TCP connection.
   105  // Most callers should just use Close.
   106  func (c *TCPConn) CloseRead() error {
   107  	if !c.ok() {
   108  		return syscall.EINVAL
   109  	}
   110  	if err := c.fd.closeRead(); err != nil {
   111  		return &OpError{Op: "close", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
   112  	}
   113  	return nil
   114  }
   115  
   116  // CloseWrite shuts down the writing side of the TCP connection.
   117  // Most callers should just use Close.
   118  func (c *TCPConn) CloseWrite() error {
   119  	if !c.ok() {
   120  		return syscall.EINVAL
   121  	}
   122  	if err := c.fd.closeWrite(); err != nil {
   123  		return &OpError{Op: "close", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
   124  	}
   125  	return nil
   126  }
   127  
   128  // SetLinger sets the behavior of Close on a connection which still
   129  // has data waiting to be sent or to be acknowledged.
   130  //
   131  // If sec < 0 (the default), the operating system finishes sending the
   132  // data in the background.
   133  //
   134  // If sec == 0, the operating system discards any unsent or
   135  // unacknowledged data.
   136  //
   137  // If sec > 0, the data is sent in the background as with sec < 0. On
   138  // some operating systems after sec seconds have elapsed any remaining
   139  // unsent data may be discarded.
   140  func (c *TCPConn) SetLinger(sec int) error {
   141  	if !c.ok() {
   142  		return syscall.EINVAL
   143  	}
   144  	if err := setLinger(c.fd, sec); err != nil {
   145  		return &OpError{Op: "set", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
   146  	}
   147  	return nil
   148  }
   149  
   150  // SetKeepAlive sets whether the operating system should send
   151  // keepalive messages on the connection.
   152  func (c *TCPConn) SetKeepAlive(keepalive bool) error {
   153  	if !c.ok() {
   154  		return syscall.EINVAL
   155  	}
   156  	if err := setKeepAlive(c.fd, keepalive); err != nil {
   157  		return &OpError{Op: "set", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
   158  	}
   159  	return nil
   160  }
   161  
   162  // SetKeepAlivePeriod sets period between keep alives.
   163  func (c *TCPConn) SetKeepAlivePeriod(d time.Duration) error {
   164  	if !c.ok() {
   165  		return syscall.EINVAL
   166  	}
   167  	if err := setKeepAlivePeriod(c.fd, d); err != nil {
   168  		return &OpError{Op: "set", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
   169  	}
   170  	return nil
   171  }
   172  
   173  // SetNoDelay controls whether the operating system should delay
   174  // packet transmission in hopes of sending fewer packets (Nagle's
   175  // algorithm).  The default is true (no delay), meaning that data is
   176  // sent as soon as possible after a Write.
   177  func (c *TCPConn) SetNoDelay(noDelay bool) error {
   178  	if !c.ok() {
   179  		return syscall.EINVAL
   180  	}
   181  	if err := setNoDelay(c.fd, noDelay); err != nil {
   182  		return &OpError{Op: "set", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
   183  	}
   184  	return nil
   185  }
   186  
   187  func newTCPConn(fd *netFD) *TCPConn {
   188  	c := &TCPConn{conn{fd}}
   189  	setNoDelay(c.fd, true)
   190  	return c
   191  }
   192  
   193  // DialTCP connects to the remote address raddr on the network net,
   194  // which must be "tcp", "tcp4", or "tcp6".  If laddr is not nil, it is
   195  // used as the local address for the connection.
   196  func DialTCP(net string, laddr, raddr *TCPAddr) (*TCPConn, error) {
   197  	switch net {
   198  	case "tcp", "tcp4", "tcp6":
   199  	default:
   200  		return nil, &OpError{Op: "dial", Net: net, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: UnknownNetworkError(net)}
   201  	}
   202  	if raddr == nil {
   203  		return nil, &OpError{Op: "dial", Net: net, Source: laddr.opAddr(), Addr: nil, Err: errMissingAddress}
   204  	}
   205  	c, err := dialTCP(context.Background(), net, laddr, raddr)
   206  	if err != nil {
   207  		return nil, &OpError{Op: "dial", Net: net, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: err}
   208  	}
   209  	return c, nil
   210  }
   211  
   212  // TCPListener is a TCP network listener. Clients should typically
   213  // use variables of type Listener instead of assuming TCP.
   214  type TCPListener struct {
   215  	fd *netFD
   216  }
   217  
   218  // AcceptTCP accepts the next incoming call and returns the new
   219  // connection.
   220  func (l *TCPListener) AcceptTCP() (*TCPConn, error) {
   221  	if !l.ok() {
   222  		return nil, syscall.EINVAL
   223  	}
   224  	c, err := l.accept()
   225  	if err != nil {
   226  		return nil, &OpError{Op: "accept", Net: l.fd.net, Source: nil, Addr: l.fd.laddr, Err: err}
   227  	}
   228  	return c, nil
   229  }
   230  
   231  // Accept implements the Accept method in the Listener interface; it
   232  // waits for the next call and returns a generic Conn.
   233  func (l *TCPListener) Accept() (Conn, error) {
   234  	if !l.ok() {
   235  		return nil, syscall.EINVAL
   236  	}
   237  	c, err := l.accept()
   238  	if err != nil {
   239  		return nil, &OpError{Op: "accept", Net: l.fd.net, Source: nil, Addr: l.fd.laddr, Err: err}
   240  	}
   241  	return c, nil
   242  }
   243  
   244  // Close stops listening on the TCP address.
   245  // Already Accepted connections are not closed.
   246  func (l *TCPListener) Close() error {
   247  	if !l.ok() {
   248  		return syscall.EINVAL
   249  	}
   250  	if err := l.close(); err != nil {
   251  		return &OpError{Op: "close", Net: l.fd.net, Source: nil, Addr: l.fd.laddr, Err: err}
   252  	}
   253  	return nil
   254  }
   255  
   256  // Addr returns the listener's network address, a *TCPAddr.
   257  // The Addr returned is shared by all invocations of Addr, so
   258  // do not modify it.
   259  func (l *TCPListener) Addr() Addr { return l.fd.laddr }
   260  
   261  // SetDeadline sets the deadline associated with the listener.
   262  // A zero time value disables the deadline.
   263  func (l *TCPListener) SetDeadline(t time.Time) error {
   264  	if !l.ok() {
   265  		return syscall.EINVAL
   266  	}
   267  	if err := l.fd.pfd.SetDeadline(t); err != nil {
   268  		return &OpError{Op: "set", Net: l.fd.net, Source: nil, Addr: l.fd.laddr, Err: err}
   269  	}
   270  	return nil
   271  }
   272  
   273  // File returns a copy of the underlying os.File, set to blocking
   274  // mode. It is the caller's responsibility to close f when finished.
   275  // Closing l does not affect f, and closing f does not affect l.
   276  //
   277  // The returned os.File's file descriptor is different from the
   278  // connection's. Attempting to change properties of the original
   279  // using this duplicate may or may not have the desired effect.
   280  func (l *TCPListener) File() (f *os.File, err error) {
   281  	if !l.ok() {
   282  		return nil, syscall.EINVAL
   283  	}
   284  	f, err = l.file()
   285  	if err != nil {
   286  		return nil, &OpError{Op: "file", Net: l.fd.net, Source: nil, Addr: l.fd.laddr, Err: err}
   287  	}
   288  	return
   289  }
   290  
   291  // ListenTCP announces on the TCP address laddr and returns a TCP
   292  // listener. Net must be "tcp", "tcp4", or "tcp6".  If laddr has a
   293  // port of 0, ListenTCP will choose an available port. The caller can
   294  // use the Addr method of TCPListener to retrieve the chosen address.
   295  func ListenTCP(net string, laddr *TCPAddr) (*TCPListener, error) {
   296  	switch net {
   297  	case "tcp", "tcp4", "tcp6":
   298  	default:
   299  		return nil, &OpError{Op: "listen", Net: net, Source: nil, Addr: laddr.opAddr(), Err: UnknownNetworkError(net)}
   300  	}
   301  	if laddr == nil {
   302  		laddr = &TCPAddr{}
   303  	}
   304  	ln, err := listenTCP(context.Background(), net, laddr)
   305  	if err != nil {
   306  		return nil, &OpError{Op: "listen", Net: net, Source: nil, Addr: laddr.opAddr(), Err: err}
   307  	}
   308  	return ln, nil
   309  }