| // 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. |
| |
| // +build darwin dragonfly freebsd linux nacl netbsd openbsd solaris windows |
| |
| package net |
| |
| import ( |
| "io" |
| "os" |
| "syscall" |
| "time" |
| ) |
| |
| // BUG(rsc): On OpenBSD, listening on the "tcp" network does not listen for |
| // both IPv4 and IPv6 connections. This is due to the fact that IPv4 traffic |
| // will not be routed to an IPv6 socket - two separate sockets are required |
| // if both AFs are to be supported. See inet6(4) on OpenBSD for details. |
| |
| func sockaddrToTCP(sa syscall.Sockaddr) Addr { |
| switch sa := sa.(type) { |
| case *syscall.SockaddrInet4: |
| return &TCPAddr{IP: sa.Addr[0:], Port: sa.Port} |
| case *syscall.SockaddrInet6: |
| return &TCPAddr{IP: sa.Addr[0:], Port: sa.Port, Zone: zoneToString(int(sa.ZoneId))} |
| } |
| return nil |
| } |
| |
| func (a *TCPAddr) family() int { |
| if a == nil || len(a.IP) <= IPv4len { |
| return syscall.AF_INET |
| } |
| if a.IP.To4() != nil { |
| return syscall.AF_INET |
| } |
| return syscall.AF_INET6 |
| } |
| |
| func (a *TCPAddr) sockaddr(family int) (syscall.Sockaddr, error) { |
| if a == nil { |
| return nil, nil |
| } |
| return ipToSockaddr(family, a.IP, a.Port, a.Zone) |
| } |
| |
| // TCPConn is an implementation of the Conn interface for TCP network |
| // connections. |
| type TCPConn struct { |
| conn |
| } |
| |
| func newTCPConn(fd *netFD) *TCPConn { |
| c := &TCPConn{conn{fd}} |
| setNoDelay(c.fd, true) |
| return c |
| } |
| |
| // ReadFrom implements the io.ReaderFrom ReadFrom method. |
| func (c *TCPConn) ReadFrom(r io.Reader) (int64, error) { |
| if n, err, handled := sendFile(c.fd, r); handled { |
| if err != nil && err != io.EOF { |
| err = &OpError{Op: "read", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err} |
| } |
| return n, err |
| } |
| n, err := genericReadFrom(c, r) |
| if err != nil && err != io.EOF { |
| err = &OpError{Op: "read", 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 |
| } |
| err := c.fd.closeRead() |
| if err != nil { |
| err = &OpError{Op: "close", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err} |
| } |
| return err |
| } |
| |
| // 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 |
| } |
| err := c.fd.closeWrite() |
| if err != nil { |
| err = &OpError{Op: "close", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err} |
| } |
| return err |
| } |
| |
| // 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 |
| } |
| |
| // 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, Addr: raddr, Err: UnknownNetworkError(net)} |
| } |
| if raddr == nil { |
| return nil, &OpError{Op: "dial", Net: net, Source: laddr, Addr: raddr, Err: errMissingAddress} |
| } |
| return dialTCP(net, laddr, raddr, noDeadline) |
| } |
| |
| func dialTCP(net string, laddr, raddr *TCPAddr, deadline time.Time) (*TCPConn, error) { |
| fd, err := internetSocket(net, laddr, raddr, deadline, syscall.SOCK_STREAM, 0, "dial") |
| |
| // TCP has a rarely used mechanism called a 'simultaneous connection' in |
| // which Dial("tcp", addr1, addr2) run on the machine at addr1 can |
| // connect to a simultaneous Dial("tcp", addr2, addr1) run on the machine |
| // at addr2, without either machine executing Listen. If laddr == nil, |
| // it means we want the kernel to pick an appropriate originating local |
| // address. Some Linux kernels cycle blindly through a fixed range of |
| // local ports, regardless of destination port. If a kernel happens to |
| // pick local port 50001 as the source for a Dial("tcp", "", "localhost:50001"), |
| // then the Dial will succeed, having simultaneously connected to itself. |
| // This can only happen when we are letting the kernel pick a port (laddr == nil) |
| // and when there is no listener for the destination address. |
| // It's hard to argue this is anything other than a kernel bug. If we |
| // see this happen, rather than expose the buggy effect to users, we |
| // close the fd and try again. If it happens twice more, we relent and |
| // use the result. See also: |
| // http://golang.org/issue/2690 |
| // http://stackoverflow.com/questions/4949858/ |
| // |
| // The opposite can also happen: if we ask the kernel to pick an appropriate |
| // originating local address, sometimes it picks one that is already in use. |
| // So if the error is EADDRNOTAVAIL, we have to try again too, just for |
| // a different reason. |
| // |
| // The kernel socket code is no doubt enjoying watching us squirm. |
| for i := 0; i < 2 && (laddr == nil || laddr.Port == 0) && (selfConnect(fd, err) || spuriousENOTAVAIL(err)); i++ { |
| if err == nil { |
| fd.Close() |
| } |
| fd, err = internetSocket(net, laddr, raddr, deadline, syscall.SOCK_STREAM, 0, "dial") |
| } |
| |
| if err != nil { |
| return nil, &OpError{Op: "dial", Net: net, Source: laddr, Addr: raddr, Err: err} |
| } |
| return newTCPConn(fd), nil |
| } |
| |
| func selfConnect(fd *netFD, err error) bool { |
| // If the connect failed, we clearly didn't connect to ourselves. |
| if err != nil { |
| return false |
| } |
| |
| // The socket constructor can return an fd with raddr nil under certain |
| // unknown conditions. The errors in the calls there to Getpeername |
| // are discarded, but we can't catch the problem there because those |
| // calls are sometimes legally erroneous with a "socket not connected". |
| // Since this code (selfConnect) is already trying to work around |
| // a problem, we make sure if this happens we recognize trouble and |
| // ask the DialTCP routine to try again. |
| // TODO: try to understand what's really going on. |
| if fd.laddr == nil || fd.raddr == nil { |
| return true |
| } |
| l := fd.laddr.(*TCPAddr) |
| r := fd.raddr.(*TCPAddr) |
| return l.Port == r.Port && l.IP.Equal(r.IP) |
| } |
| |
| func spuriousENOTAVAIL(err error) bool { |
| e, ok := err.(*OpError) |
| return ok && e.Err == syscall.EADDRNOTAVAIL |
| } |
| |
| // 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 == nil || l.fd == nil { |
| return nil, syscall.EINVAL |
| } |
| fd, err := l.fd.accept() |
| if err != nil { |
| return nil, &OpError{Op: "accept", Net: l.fd.net, Source: nil, Addr: l.fd.laddr, Err: err} |
| } |
| return newTCPConn(fd), 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) { |
| c, err := l.AcceptTCP() |
| if err != nil { |
| return nil, err |
| } |
| return c, nil |
| } |
| |
| // Close stops listening on the TCP address. |
| // Already Accepted connections are not closed. |
| func (l *TCPListener) Close() error { |
| if l == nil || l.fd == nil { |
| return syscall.EINVAL |
| } |
| err := l.fd.Close() |
| if err != nil { |
| err = &OpError{Op: "close", Net: l.fd.net, Source: nil, Addr: l.fd.laddr, Err: err} |
| } |
| return err |
| } |
| |
| // 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 == nil || l.fd == nil { |
| 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) { |
| f, err = l.fd.dup() |
| if err != nil { |
| err = &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, Err: UnknownNetworkError(net)} |
| } |
| if laddr == nil { |
| laddr = &TCPAddr{} |
| } |
| fd, err := internetSocket(net, laddr, nil, noDeadline, syscall.SOCK_STREAM, 0, "listen") |
| if err != nil { |
| return nil, &OpError{Op: "listen", Net: net, Source: nil, Addr: laddr, Err: err} |
| } |
| return &TCPListener{fd}, nil |
| } |