Source file src/net/tcpsock.go

  // Copyright 2009 The Go Authors. All rights reserved.
  // Use of this source code is governed by a BSD-style
  // license that can be found in the LICENSE file.
  
  package net
  
  import (
  	"context"
  	"io"
  	"os"
  	"syscall"
  	"time"
  )
  
  // BUG(mikio): On Windows, the File method of TCPListener is not
  // implemented.
  
  // TCPAddr represents the address of a TCP end point.
  type TCPAddr struct {
  	IP   IP
  	Port int
  	Zone string // IPv6 scoped addressing zone
  }
  
  // Network returns the address's network name, "tcp".
  func (a *TCPAddr) Network() string { return "tcp" }
  
  func (a *TCPAddr) String() string {
  	if a == nil {
  		return "<nil>"
  	}
  	ip := ipEmptyString(a.IP)
  	if a.Zone != "" {
  		return JoinHostPort(ip+"%"+a.Zone, itoa(a.Port))
  	}
  	return JoinHostPort(ip, itoa(a.Port))
  }
  
  func (a *TCPAddr) isWildcard() bool {
  	if a == nil || a.IP == nil {
  		return true
  	}
  	return a.IP.IsUnspecified()
  }
  
  func (a *TCPAddr) opAddr() Addr {
  	if a == nil {
  		return nil
  	}
  	return a
  }
  
  // ResolveTCPAddr parses addr as a TCP address of the form "host:port"
  // or "[ipv6-host%zone]:port" and resolves a pair of domain name and
  // port name on the network net, which must be "tcp", "tcp4" or
  // "tcp6".  A literal address or host name for IPv6 must be enclosed
  // in square brackets, as in "[::1]:80", "[ipv6-host]:http" or
  // "[ipv6-host%zone]:80".
  //
  // Resolving a hostname is not recommended because this returns at most
  // one of its IP addresses.
  func ResolveTCPAddr(net, addr string) (*TCPAddr, error) {
  	switch net {
  	case "tcp", "tcp4", "tcp6":
  	case "": // a hint wildcard for Go 1.0 undocumented behavior
  		net = "tcp"
  	default:
  		return nil, UnknownNetworkError(net)
  	}
  	addrs, err := DefaultResolver.internetAddrList(context.Background(), net, addr)
  	if err != nil {
  		return nil, err
  	}
  	return addrs.first(isIPv4).(*TCPAddr), nil
  }
  
  // TCPConn is an implementation of the Conn interface for TCP network
  // connections.
  type TCPConn struct {
  	conn
  }
  
  // ReadFrom implements the io.ReaderFrom ReadFrom method.
  func (c *TCPConn) ReadFrom(r io.Reader) (int64, error) {
  	if !c.ok() {
  		return 0, syscall.EINVAL
  	}
  	n, err := c.readFrom(r)
  	if err != nil && err != io.EOF {
  		err = &OpError{Op: "readfrom", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
  	}
  	return n, err
  }
  
  // CloseRead shuts down the reading side of the TCP connection.
  // Most callers should just use Close.
  func (c *TCPConn) CloseRead() error {
  	if !c.ok() {
  		return syscall.EINVAL
  	}
  	if err := c.fd.closeRead(); err != nil {
  		return &OpError{Op: "close", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
  	}
  	return nil
  }
  
  // CloseWrite shuts down the writing side of the TCP connection.
  // Most callers should just use Close.
  func (c *TCPConn) CloseWrite() error {
  	if !c.ok() {
  		return syscall.EINVAL
  	}
  	if err := c.fd.closeWrite(); err != nil {
  		return &OpError{Op: "close", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
  	}
  	return nil
  }
  
  // SetLinger sets the behavior of Close on a connection which still
  // has data waiting to be sent or to be acknowledged.
  //
  // If sec < 0 (the default), the operating system finishes sending the
  // data in the background.
  //
  // If sec == 0, the operating system discards any unsent or
  // unacknowledged data.
  //
  // If sec > 0, the data is sent in the background as with sec < 0. On
  // some operating systems after sec seconds have elapsed any remaining
  // unsent data may be discarded.
  func (c *TCPConn) SetLinger(sec int) error {
  	if !c.ok() {
  		return syscall.EINVAL
  	}
  	if err := setLinger(c.fd, sec); err != nil {
  		return &OpError{Op: "set", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
  	}
  	return nil
  }
  
  // SetKeepAlive sets whether the operating system should send
  // keepalive messages on the connection.
  func (c *TCPConn) SetKeepAlive(keepalive bool) error {
  	if !c.ok() {
  		return syscall.EINVAL
  	}
  	if err := setKeepAlive(c.fd, keepalive); err != nil {
  		return &OpError{Op: "set", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
  	}
  	return nil
  }
  
  // SetKeepAlivePeriod sets period between keep alives.
  func (c *TCPConn) SetKeepAlivePeriod(d time.Duration) error {
  	if !c.ok() {
  		return syscall.EINVAL
  	}
  	if err := setKeepAlivePeriod(c.fd, d); err != nil {
  		return &OpError{Op: "set", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
  	}
  	return nil
  }
  
  // SetNoDelay controls whether the operating system should delay
  // packet transmission in hopes of sending fewer packets (Nagle's
  // algorithm).  The default is true (no delay), meaning that data is
  // sent as soon as possible after a Write.
  func (c *TCPConn) SetNoDelay(noDelay bool) error {
  	if !c.ok() {
  		return syscall.EINVAL
  	}
  	if err := setNoDelay(c.fd, noDelay); err != nil {
  		return &OpError{Op: "set", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
  	}
  	return nil
  }
  
  func newTCPConn(fd *netFD) *TCPConn {
  	c := &TCPConn{conn{fd}}
  	setNoDelay(c.fd, true)
  	return c
  }
  
  // DialTCP connects to the remote address raddr on the network net,
  // which must be "tcp", "tcp4", or "tcp6".  If laddr is not nil, it is
  // used as the local address for the connection.
  func DialTCP(net string, laddr, raddr *TCPAddr) (*TCPConn, error) {
  	switch net {
  	case "tcp", "tcp4", "tcp6":
  	default:
  		return nil, &OpError{Op: "dial", Net: net, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: UnknownNetworkError(net)}
  	}
  	if raddr == nil {
  		return nil, &OpError{Op: "dial", Net: net, Source: laddr.opAddr(), Addr: nil, Err: errMissingAddress}
  	}
  	c, err := dialTCP(context.Background(), net, laddr, raddr)
  	if err != nil {
  		return nil, &OpError{Op: "dial", Net: net, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: err}
  	}
  	return c, nil
  }
  
  // TCPListener is a TCP network listener. Clients should typically
  // use variables of type Listener instead of assuming TCP.
  type TCPListener struct {
  	fd *netFD
  }
  
  // AcceptTCP accepts the next incoming call and returns the new
  // connection.
  func (l *TCPListener) AcceptTCP() (*TCPConn, error) {
  	if !l.ok() {
  		return nil, syscall.EINVAL
  	}
  	c, err := l.accept()
  	if err != nil {
  		return nil, &OpError{Op: "accept", Net: l.fd.net, Source: nil, Addr: l.fd.laddr, Err: err}
  	}
  	return c, nil
  }
  
  // Accept implements the Accept method in the Listener interface; it
  // waits for the next call and returns a generic Conn.
  func (l *TCPListener) Accept() (Conn, error) {
  	if !l.ok() {
  		return nil, syscall.EINVAL
  	}
  	c, err := l.accept()
  	if err != nil {
  		return nil, &OpError{Op: "accept", Net: l.fd.net, Source: nil, Addr: l.fd.laddr, Err: err}
  	}
  	return c, nil
  }
  
  // Close stops listening on the TCP address.
  // Already Accepted connections are not closed.
  func (l *TCPListener) Close() error {
  	if !l.ok() {
  		return syscall.EINVAL
  	}
  	if err := l.close(); err != nil {
  		return &OpError{Op: "close", Net: l.fd.net, Source: nil, Addr: l.fd.laddr, Err: err}
  	}
  	return nil
  }
  
  // Addr returns the listener's network address, a *TCPAddr.
  // The Addr returned is shared by all invocations of Addr, so
  // do not modify it.
  func (l *TCPListener) Addr() Addr { return l.fd.laddr }
  
  // SetDeadline sets the deadline associated with the listener.
  // A zero time value disables the deadline.
  func (l *TCPListener) SetDeadline(t time.Time) error {
  	if !l.ok() {
  		return syscall.EINVAL
  	}
  	if err := l.fd.setDeadline(t); err != nil {
  		return &OpError{Op: "set", Net: l.fd.net, Source: nil, Addr: l.fd.laddr, Err: err}
  	}
  	return nil
  }
  
  // File returns a copy of the underlying os.File, set to blocking
  // mode. It is the caller's responsibility to close f when finished.
  // Closing l does not affect f, and closing f does not affect l.
  //
  // The returned os.File's file descriptor is different from the
  // connection's. Attempting to change properties of the original
  // using this duplicate may or may not have the desired effect.
  func (l *TCPListener) File() (f *os.File, err error) {
  	if !l.ok() {
  		return nil, syscall.EINVAL
  	}
  	f, err = l.file()
  	if err != nil {
  		return nil, &OpError{Op: "file", Net: l.fd.net, Source: nil, Addr: l.fd.laddr, Err: err}
  	}
  	return
  }
  
  // ListenTCP announces on the TCP address laddr and returns a TCP
  // listener. Net must be "tcp", "tcp4", or "tcp6".  If laddr has a
  // port of 0, ListenTCP will choose an available port. The caller can
  // use the Addr method of TCPListener to retrieve the chosen address.
  func ListenTCP(net string, laddr *TCPAddr) (*TCPListener, error) {
  	switch net {
  	case "tcp", "tcp4", "tcp6":
  	default:
  		return nil, &OpError{Op: "listen", Net: net, Source: nil, Addr: laddr.opAddr(), Err: UnknownNetworkError(net)}
  	}
  	if laddr == nil {
  		laddr = &TCPAddr{}
  	}
  	ln, err := listenTCP(context.Background(), net, laddr)
  	if err != nil {
  		return nil, &OpError{Op: "listen", Net: net, Source: nil, Addr: laddr.opAddr(), Err: err}
  	}
  	return ln, nil
  }
  

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