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// 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 (
"context"
"internal/poll"
"os"
"syscall"
)
// A sockaddr represents a TCP, UDP, IP or Unix network endpoint
// address that can be converted into a syscall.Sockaddr.
type sockaddr interface {
Addr
// family returns the platform-dependent address family
// identifier.
family() int
// isWildcard reports whether the address is a wildcard
// address.
isWildcard() bool
// sockaddr returns the address converted into a syscall
// sockaddr type that implements syscall.Sockaddr
// interface. It returns a nil interface when the address is
// nil.
sockaddr(family int) (syscall.Sockaddr, error)
// toLocal maps the zero address to a local system address (127.0.0.1 or ::1)
toLocal(net string) sockaddr
}
// 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) (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); err != nil {
fd.Close()
return nil, err
}
return fd, nil
case syscall.SOCK_DGRAM:
if err := fd.listenDatagram(laddr); err != nil {
fd.Close()
return nil, err
}
return fd, nil
}
}
if err := fd.dial(ctx, laddr, raddr); err != nil {
fd.Close()
return nil, err
}
return fd, nil
}
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) error {
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) error {
if err := setDefaultListenerSockopts(fd.pfd.Sysfd); err != nil {
return err
}
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)
}
}
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) 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
}
}
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)
}
}
if err := fd.init(); err != nil {
return err
}
lsa, _ := syscall.Getsockname(fd.pfd.Sysfd)
fd.setAddr(fd.addrFunc()(lsa), nil)
return nil
}
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