335 lines
11 KiB
Go
335 lines
11 KiB
Go
// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// +build darwin dragonfly freebsd linux nacl netbsd openbsd solaris windows
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package net
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import (
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"io"
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"os"
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"syscall"
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"time"
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)
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func sockaddrToTCP(sa syscall.Sockaddr) Addr {
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switch sa := sa.(type) {
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case *syscall.SockaddrInet4:
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return &TCPAddr{IP: sa.Addr[0:], Port: sa.Port}
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case *syscall.SockaddrInet6:
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return &TCPAddr{IP: sa.Addr[0:], Port: sa.Port, Zone: zoneToString(int(sa.ZoneId))}
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}
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return nil
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}
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func (a *TCPAddr) family() int {
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if a == nil || len(a.IP) <= IPv4len {
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return syscall.AF_INET
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}
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if a.IP.To4() != nil {
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return syscall.AF_INET
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}
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return syscall.AF_INET6
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}
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func (a *TCPAddr) sockaddr(family int) (syscall.Sockaddr, error) {
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if a == nil {
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return nil, nil
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}
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return ipToSockaddr(family, a.IP, a.Port, a.Zone)
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}
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// TCPConn is an implementation of the Conn interface for TCP network
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// connections.
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type TCPConn struct {
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conn
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}
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func newTCPConn(fd *netFD) *TCPConn {
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c := &TCPConn{conn{fd}}
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setNoDelay(c.fd, true)
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return c
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}
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// ReadFrom implements the io.ReaderFrom ReadFrom method.
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func (c *TCPConn) ReadFrom(r io.Reader) (int64, error) {
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if n, err, handled := sendFile(c.fd, r); handled {
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if err != nil && err != io.EOF {
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err = &OpError{Op: "read", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
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}
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return n, err
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}
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n, err := genericReadFrom(c, r)
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if err != nil && err != io.EOF {
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err = &OpError{Op: "read", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
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}
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return n, err
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}
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// CloseRead shuts down the reading side of the TCP connection.
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// Most callers should just use Close.
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func (c *TCPConn) CloseRead() error {
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if !c.ok() {
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return syscall.EINVAL
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}
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err := c.fd.closeRead()
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if err != nil {
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err = &OpError{Op: "close", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
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}
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return err
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}
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// CloseWrite shuts down the writing side of the TCP connection.
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// Most callers should just use Close.
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func (c *TCPConn) CloseWrite() error {
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if !c.ok() {
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return syscall.EINVAL
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}
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err := c.fd.closeWrite()
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if err != nil {
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err = &OpError{Op: "close", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
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}
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return err
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}
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// SetLinger sets the behavior of Close on a connection which still
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// has data waiting to be sent or to be acknowledged.
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//
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// If sec < 0 (the default), the operating system finishes sending the
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// data in the background.
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//
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// If sec == 0, the operating system discards any unsent or
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// unacknowledged data.
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//
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// If sec > 0, the data is sent in the background as with sec < 0. On
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// some operating systems after sec seconds have elapsed any remaining
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// unsent data may be discarded.
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func (c *TCPConn) SetLinger(sec int) error {
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if !c.ok() {
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return syscall.EINVAL
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}
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if err := setLinger(c.fd, sec); err != nil {
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return &OpError{Op: "set", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
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}
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return nil
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}
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// SetKeepAlive sets whether the operating system should send
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// keepalive messages on the connection.
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func (c *TCPConn) SetKeepAlive(keepalive bool) error {
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if !c.ok() {
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return syscall.EINVAL
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}
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if err := setKeepAlive(c.fd, keepalive); err != nil {
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return &OpError{Op: "set", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
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}
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return nil
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}
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// SetKeepAlivePeriod sets period between keep alives.
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func (c *TCPConn) SetKeepAlivePeriod(d time.Duration) error {
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if !c.ok() {
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return syscall.EINVAL
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}
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if err := setKeepAlivePeriod(c.fd, d); err != nil {
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return &OpError{Op: "set", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
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}
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return nil
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}
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// SetNoDelay controls whether the operating system should delay
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// packet transmission in hopes of sending fewer packets (Nagle's
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// algorithm). The default is true (no delay), meaning that data is
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// sent as soon as possible after a Write.
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func (c *TCPConn) SetNoDelay(noDelay bool) error {
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if !c.ok() {
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return syscall.EINVAL
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}
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if err := setNoDelay(c.fd, noDelay); err != nil {
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return &OpError{Op: "set", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
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}
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return nil
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}
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// DialTCP connects to the remote address raddr on the network net,
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// which must be "tcp", "tcp4", or "tcp6". If laddr is not nil, it is
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// used as the local address for the connection.
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func DialTCP(net string, laddr, raddr *TCPAddr) (*TCPConn, error) {
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switch net {
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case "tcp", "tcp4", "tcp6":
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default:
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return nil, &OpError{Op: "dial", Net: net, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: UnknownNetworkError(net)}
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}
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if raddr == nil {
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return nil, &OpError{Op: "dial", Net: net, Source: laddr.opAddr(), Addr: nil, Err: errMissingAddress}
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}
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return dialTCP(net, laddr, raddr, noDeadline, noCancel)
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}
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func dialTCP(net string, laddr, raddr *TCPAddr, deadline time.Time, cancel <-chan struct{}) (*TCPConn, error) {
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fd, err := internetSocket(net, laddr, raddr, deadline, syscall.SOCK_STREAM, 0, "dial", cancel)
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// TCP has a rarely used mechanism called a 'simultaneous connection' in
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// which Dial("tcp", addr1, addr2) run on the machine at addr1 can
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// connect to a simultaneous Dial("tcp", addr2, addr1) run on the machine
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// at addr2, without either machine executing Listen. If laddr == nil,
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// it means we want the kernel to pick an appropriate originating local
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// address. Some Linux kernels cycle blindly through a fixed range of
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// local ports, regardless of destination port. If a kernel happens to
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// pick local port 50001 as the source for a Dial("tcp", "", "localhost:50001"),
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// then the Dial will succeed, having simultaneously connected to itself.
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// This can only happen when we are letting the kernel pick a port (laddr == nil)
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// and when there is no listener for the destination address.
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// It's hard to argue this is anything other than a kernel bug. If we
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// see this happen, rather than expose the buggy effect to users, we
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// close the fd and try again. If it happens twice more, we relent and
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// use the result. See also:
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// https://golang.org/issue/2690
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// http://stackoverflow.com/questions/4949858/
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//
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// The opposite can also happen: if we ask the kernel to pick an appropriate
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// originating local address, sometimes it picks one that is already in use.
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// So if the error is EADDRNOTAVAIL, we have to try again too, just for
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// a different reason.
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//
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// The kernel socket code is no doubt enjoying watching us squirm.
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for i := 0; i < 2 && (laddr == nil || laddr.Port == 0) && (selfConnect(fd, err) || spuriousENOTAVAIL(err)); i++ {
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if err == nil {
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fd.Close()
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}
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fd, err = internetSocket(net, laddr, raddr, deadline, syscall.SOCK_STREAM, 0, "dial", cancel)
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}
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if err != nil {
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return nil, &OpError{Op: "dial", Net: net, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: err}
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}
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return newTCPConn(fd), nil
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}
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func selfConnect(fd *netFD, err error) bool {
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// If the connect failed, we clearly didn't connect to ourselves.
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if err != nil {
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return false
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}
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// The socket constructor can return an fd with raddr nil under certain
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// unknown conditions. The errors in the calls there to Getpeername
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// are discarded, but we can't catch the problem there because those
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// calls are sometimes legally erroneous with a "socket not connected".
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// Since this code (selfConnect) is already trying to work around
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// a problem, we make sure if this happens we recognize trouble and
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// ask the DialTCP routine to try again.
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// TODO: try to understand what's really going on.
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if fd.laddr == nil || fd.raddr == nil {
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return true
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}
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l := fd.laddr.(*TCPAddr)
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r := fd.raddr.(*TCPAddr)
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return l.Port == r.Port && l.IP.Equal(r.IP)
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}
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func spuriousENOTAVAIL(err error) bool {
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if op, ok := err.(*OpError); ok {
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err = op.Err
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}
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if sys, ok := err.(*os.SyscallError); ok {
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err = sys.Err
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}
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return err == syscall.EADDRNOTAVAIL
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}
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// TCPListener is a TCP network listener. Clients should typically
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// use variables of type Listener instead of assuming TCP.
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type TCPListener struct {
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fd *netFD
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}
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// AcceptTCP accepts the next incoming call and returns the new
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// connection.
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func (l *TCPListener) AcceptTCP() (*TCPConn, error) {
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if l == nil || l.fd == nil {
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return nil, syscall.EINVAL
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}
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fd, err := l.fd.accept()
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if err != nil {
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return nil, &OpError{Op: "accept", Net: l.fd.net, Source: nil, Addr: l.fd.laddr, Err: err}
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}
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return newTCPConn(fd), nil
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}
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// Accept implements the Accept method in the Listener interface; it
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// waits for the next call and returns a generic Conn.
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func (l *TCPListener) Accept() (Conn, error) {
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c, err := l.AcceptTCP()
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if err != nil {
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return nil, err
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}
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return c, nil
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}
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// Close stops listening on the TCP address.
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// Already Accepted connections are not closed.
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func (l *TCPListener) Close() error {
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if l == nil || l.fd == nil {
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return syscall.EINVAL
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}
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err := l.fd.Close()
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if err != nil {
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err = &OpError{Op: "close", Net: l.fd.net, Source: nil, Addr: l.fd.laddr, Err: err}
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}
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return err
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}
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// Addr returns the listener's network address, a *TCPAddr.
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// The Addr returned is shared by all invocations of Addr, so
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// do not modify it.
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func (l *TCPListener) Addr() Addr { return l.fd.laddr }
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// SetDeadline sets the deadline associated with the listener.
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// A zero time value disables the deadline.
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func (l *TCPListener) SetDeadline(t time.Time) error {
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if l == nil || l.fd == nil {
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return syscall.EINVAL
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}
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if err := l.fd.setDeadline(t); err != nil {
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return &OpError{Op: "set", Net: l.fd.net, Source: nil, Addr: l.fd.laddr, Err: err}
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}
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return nil
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}
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// File returns a copy of the underlying os.File, set to blocking
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// mode. It is the caller's responsibility to close f when finished.
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// Closing l does not affect f, and closing f does not affect l.
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//
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// The returned os.File's file descriptor is different from the
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// connection's. Attempting to change properties of the original
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// using this duplicate may or may not have the desired effect.
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func (l *TCPListener) File() (f *os.File, err error) {
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f, err = l.fd.dup()
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if err != nil {
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err = &OpError{Op: "file", Net: l.fd.net, Source: nil, Addr: l.fd.laddr, Err: err}
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}
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return
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}
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// ListenTCP announces on the TCP address laddr and returns a TCP
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// listener. Net must be "tcp", "tcp4", or "tcp6". If laddr has a
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// port of 0, ListenTCP will choose an available port. The caller can
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// use the Addr method of TCPListener to retrieve the chosen address.
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func ListenTCP(net string, laddr *TCPAddr) (*TCPListener, error) {
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switch net {
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case "tcp", "tcp4", "tcp6":
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default:
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return nil, &OpError{Op: "listen", Net: net, Source: nil, Addr: laddr.opAddr(), Err: UnknownNetworkError(net)}
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}
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if laddr == nil {
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laddr = &TCPAddr{}
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}
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fd, err := internetSocket(net, laddr, nil, noDeadline, syscall.SOCK_STREAM, 0, "listen", noCancel)
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if err != nil {
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return nil, &OpError{Op: "listen", Net: net, Source: nil, Addr: laddr, Err: err}
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}
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return &TCPListener{fd}, nil
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}
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