src/internal/poll/fd_unix.go:85
// Close closes the FD. The underlying file descriptor is closed by the
// destroy method when there are no remaining references.
func (fd *FD) Close() error {
if !fd.fdmu.increfAndClose() {
return errClosing(fd.isFile)
}
// Unblock any I/O. Once it all unblocks and returns,
// so that it cannot be referring to fd.sysfd anymore,
// the final decref will close fd.sysfd. This should happen
// fairly quickly, since all the I/O is non-blocking, and any
// attempts to block in the pollDesc will return errClosing(fd.isFile).
fd.pd.evict()
// The call to decref will call destroy if there are no other
// references.
err := fd.decref()
// Wait until the descriptor is closed. If this was the only
// reference, it is already closed. Only wait if the file has
// not been set to blocking mode, as otherwise any current I/O
// may be blocking, and that would block the Close.
// No need for an atomic read of isBlocking, increfAndClose means
// we have exclusive access to fd.
if fd.isBlocking == 0 {
runtime_Semacquire(&fd.csema)
}
return err
}
src/net/sock_posix.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.
// +build aix darwin dragonfly freebsd linux netbsd openbsd solaris windows
package net
import (
"context"
"internal/poll"
"os"
"syscall"
)
// socket returns a network file descriptor that is ready for
// asynchronous I/O using the network poller.
func socket(ctx context.Context, net string, family, sotype, proto int, ipv6only bool, laddr, raddr sockaddr, ctrlFn func(string, string, syscall.RawConn) error) (fd *netFD, err error) {
s, err := sysSocket(family, sotype, proto)
if err != nil {
return nil, err
}
if err = setDefaultSockopts(s, family, sotype, ipv6only); err != nil {
poll.CloseFunc(s)
return nil, err
}
if fd, err = newFD(s, family, sotype, net); err != nil {
poll.CloseFunc(s)
return nil, err
}
// This function makes a network file descriptor for the
// following applications:
//
// - An endpoint holder that opens a passive stream
// connection, known as a stream listener
//
// - An endpoint holder that opens a destination-unspecific
// datagram connection, known as a datagram listener
//
// - An endpoint holder that opens an active stream or a
// destination-specific datagram connection, known as a
// dialer
//
// - An endpoint holder that opens the other connection, such
// as talking to the protocol stack inside the kernel
//
// For stream and datagram listeners, they will only require
// named sockets, so we can assume that it's just a request
// from stream or datagram listeners when laddr is not nil but
// raddr is nil. Otherwise we assume it's just for dialers or
// the other connection holders.
if laddr != nil && raddr == nil {
switch sotype {
case syscall.SOCK_STREAM, syscall.SOCK_SEQPACKET:
if err := fd.listenStream(laddr, listenerBacklog(), ctrlFn); err != nil {
fd.Close()
return nil, err
}
return fd, nil
case syscall.SOCK_DGRAM:
if err := fd.listenDatagram(laddr, ctrlFn); err != nil {
fd.Close()
return nil, err
}
return fd, nil
}
}
if err := fd.dial(ctx, laddr, raddr, ctrlFn); err != nil {
fd.Close()
return nil, err
}
return fd, nil
}
func (fd *netFD) ctrlNetwork() string {
switch fd.net {
case "unix", "unixgram", "unixpacket":
return fd.net
}
switch fd.net[len(fd.net)-1] {
case '4', '6':
return fd.net
}
if fd.family == syscall.AF_INET {
return fd.net + "4"
}
return fd.net + "6"
}
func (fd *netFD) addrFunc() func(syscall.Sockaddr) Addr {
switch fd.family {
case syscall.AF_INET, syscall.AF_INET6:
switch fd.sotype {
case syscall.SOCK_STREAM:
return sockaddrToTCP
case syscall.SOCK_DGRAM:
return sockaddrToUDP
case syscall.SOCK_RAW:
return sockaddrToIP
}
case syscall.AF_UNIX:
switch fd.sotype {
case syscall.SOCK_STREAM:
return sockaddrToUnix
case syscall.SOCK_DGRAM:
return sockaddrToUnixgram
case syscall.SOCK_SEQPACKET:
return sockaddrToUnixpacket
}
}
return func(syscall.Sockaddr) Addr { return nil }
}
func (fd *netFD) dial(ctx context.Context, laddr, raddr sockaddr, ctrlFn func(string, string, syscall.RawConn) error) error {
if ctrlFn != nil {
c, err := newRawConn(fd)
if err != nil {
return err
}
var ctrlAddr string
if raddr != nil {
ctrlAddr = raddr.String()
} else if laddr != nil {
ctrlAddr = laddr.String()
}
if err := ctrlFn(fd.ctrlNetwork(), ctrlAddr, c); err != nil {
return err
}
}
var err error
var lsa syscall.Sockaddr
if laddr != nil {
if lsa, err = laddr.sockaddr(fd.family); err != nil {
return err
} else if lsa != nil {
if err = syscall.Bind(fd.pfd.Sysfd, lsa); err != nil {
return os.NewSyscallError("bind", err)
}
}
}
var rsa syscall.Sockaddr // remote address from the user
var crsa syscall.Sockaddr // remote address we actually connected to
if raddr != nil {
if rsa, err = raddr.sockaddr(fd.family); err != nil {
return err
}
if crsa, err = fd.connect(ctx, lsa, rsa); err != nil {
return err
}
fd.isConnected = true
} else {
if err := fd.init(); err != nil {
return err
}
}
// Record the local and remote addresses from the actual socket.
// Get the local address by calling Getsockname.
// For the remote address, use
// 1) the one returned by the connect method, if any; or
// 2) the one from Getpeername, if it succeeds; or
// 3) the one passed to us as the raddr parameter.
lsa, _ = syscall.Getsockname(fd.pfd.Sysfd)
if crsa != nil {
fd.setAddr(fd.addrFunc()(lsa), fd.addrFunc()(crsa))
} else if rsa, _ = syscall.Getpeername(fd.pfd.Sysfd); rsa != nil {
fd.setAddr(fd.addrFunc()(lsa), fd.addrFunc()(rsa))
} else {
fd.setAddr(fd.addrFunc()(lsa), raddr)
}
return nil
}
func (fd *netFD) listenStream(laddr sockaddr, backlog int, ctrlFn func(string, string, syscall.RawConn) error) error {
var err error
if err = setDefaultListenerSockopts(fd.pfd.Sysfd); err != nil {
return err
}
var lsa syscall.Sockaddr
if lsa, err = laddr.sockaddr(fd.family); err != nil {
return err
}
if ctrlFn != nil {
c, err := newRawConn(fd)
if err != nil {
return err
}
if err := ctrlFn(fd.ctrlNetwork(), laddr.String(), c); err != nil {
return err
}
}
if err = syscall.Bind(fd.pfd.Sysfd, lsa); err != nil {
return os.NewSyscallError("bind", err)
}
if err = listenFunc(fd.pfd.Sysfd, backlog); err != nil {
return os.NewSyscallError("listen", err)
}
if err = fd.init(); err != nil {
return err
}
lsa, _ = syscall.Getsockname(fd.pfd.Sysfd)
fd.setAddr(fd.addrFunc()(lsa), nil)
return nil
}
func (fd *netFD) listenDatagram(laddr sockaddr, ctrlFn func(string, string, syscall.RawConn) error) error {
switch addr := laddr.(type) {
case *UDPAddr:
// We provide a socket that listens to a wildcard
// address with reusable UDP port when the given laddr
// is an appropriate UDP multicast address prefix.
// This makes it possible for a single UDP listener to
// join multiple different group addresses, for
// multiple UDP listeners that listen on the same UDP
// port to join the same group address.
if addr.IP != nil && addr.IP.IsMulticast() {
if err := setDefaultMulticastSockopts(fd.pfd.Sysfd); err != nil {
return err
}
addr := *addr
switch fd.family {
case syscall.AF_INET:
addr.IP = IPv4zero
case syscall.AF_INET6:
addr.IP = IPv6unspecified
}
laddr = &addr
}
}
var err error
var lsa syscall.Sockaddr
if lsa, err = laddr.sockaddr(fd.family); err != nil {
return err
}
if ctrlFn != nil {
c, err := newRawConn(fd)
if err != nil {
return err
}
if err := ctrlFn(fd.ctrlNetwork(), laddr.String(), c); err != nil {
return err
}
}
if err = syscall.Bind(fd.pfd.Sysfd, lsa); err != nil {
return os.NewSyscallError("bind", err)
}
if err = fd.init(); err != nil {
return err
}
lsa, _ = syscall.Getsockname(fd.pfd.Sysfd)
fd.setAddr(fd.addrFunc()(lsa), nil)
return nil
}
golang 网络编程之如何正确关闭tcp连接以及管理它的生命周期 - 就想叫yoko - 博客园 https://www.cnblogs.com/notokoy/p/11067932.html