237 lines
5.9 KiB
Go
237 lines
5.9 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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// IP sockets
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package net
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import (
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"os"
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"syscall"
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)
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// Should we try to use the IPv4 socket interface if we're
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// only dealing with IPv4 sockets? As long as the host system
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// understands IPv6, it's okay to pass IPv4 addresses to the IPv6
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// interface. That simplifies our code and is most general.
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// Unfortunately, we need to run on kernels built without IPv6 support too.
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// So probe the kernel to figure it out.
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func kernelSupportsIPv6() bool {
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// FreeBSD does not support this sort of interface.
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if syscall.OS == "freebsd" {
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return false
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}
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fd, e := syscall.Socket(syscall.AF_INET6, syscall.SOCK_STREAM, syscall.IPPROTO_TCP)
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if fd >= 0 {
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syscall.Close(fd)
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}
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return e == 0
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}
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var preferIPv4 = !kernelSupportsIPv6()
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// TODO(rsc): if syscall.OS == "linux", we're supposd to read
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// /proc/sys/net/core/somaxconn,
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// to take advantage of kernels that have raised the limit.
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func listenBacklog() int { return syscall.SOMAXCONN }
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// Internet sockets (TCP, UDP)
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// A sockaddr represents a TCP or UDP network address that can
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// be converted into a syscall.Sockaddr.
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type sockaddr interface {
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Addr
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sockaddr(family int) (syscall.Sockaddr, os.Error)
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family() int
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}
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func internetSocket(net string, laddr, raddr sockaddr, socktype, proto int, mode string, toAddr func(syscall.Sockaddr) Addr) (fd *netFD, err os.Error) {
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// Figure out IP version.
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// If network has a suffix like "tcp4", obey it.
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var oserr os.Error
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family := syscall.AF_INET6
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switch net[len(net)-1] {
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case '4':
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family = syscall.AF_INET
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case '6':
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// nothing to do
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default:
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// Otherwise, guess.
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// If the addresses are IPv4 and we prefer IPv4, use 4; else 6.
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if preferIPv4 &&
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(laddr == nil || laddr.family() == syscall.AF_INET) &&
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(raddr == nil || raddr.family() == syscall.AF_INET) {
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family = syscall.AF_INET
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}
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}
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var la, ra syscall.Sockaddr
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if laddr != nil {
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if la, oserr = laddr.sockaddr(family); oserr != nil {
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goto Error
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}
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}
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if raddr != nil {
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if ra, oserr = raddr.sockaddr(family); oserr != nil {
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goto Error
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}
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}
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fd, oserr = socket(net, family, socktype, proto, la, ra, toAddr)
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if oserr != nil {
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goto Error
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}
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return fd, nil
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Error:
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addr := raddr
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if mode == "listen" {
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addr = laddr
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}
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return nil, &OpError{mode, net, addr, oserr}
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}
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func getip(fd int, remote bool) (ip []byte, port int, ok bool) {
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// No attempt at error reporting because
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// there are no possible errors, and the
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// caller won't report them anyway.
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var sa syscall.Sockaddr
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if remote {
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sa, _ = syscall.Getpeername(fd)
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} else {
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sa, _ = syscall.Getsockname(fd)
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}
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switch sa := sa.(type) {
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case *syscall.SockaddrInet4:
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return sa.Addr[0:], sa.Port, true
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case *syscall.SockaddrInet6:
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return sa.Addr[0:], sa.Port, true
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}
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return
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}
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type InvalidAddrError string
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func (e InvalidAddrError) String() string { return string(e) }
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func (e InvalidAddrError) Timeout() bool { return false }
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func (e InvalidAddrError) Temporary() bool { return false }
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func ipToSockaddr(family int, ip IP, port int) (syscall.Sockaddr, os.Error) {
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switch family {
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case syscall.AF_INET:
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if len(ip) == 0 {
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ip = IPv4zero
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}
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if ip = ip.To4(); ip == nil {
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return nil, InvalidAddrError("non-IPv4 address")
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}
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s := new(syscall.SockaddrInet4)
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for i := 0; i < IPv4len; i++ {
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s.Addr[i] = ip[i]
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}
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s.Port = port
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return s, nil
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case syscall.AF_INET6:
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if len(ip) == 0 {
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ip = IPzero
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}
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// IPv4 callers use 0.0.0.0 to mean "announce on any available address".
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// In IPv6 mode, Linux treats that as meaning "announce on 0.0.0.0",
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// which it refuses to do. Rewrite to the IPv6 all zeros.
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if p4 := ip.To4(); p4 != nil && p4[0] == 0 && p4[1] == 0 && p4[2] == 0 && p4[3] == 0 {
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ip = IPzero
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}
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if ip = ip.To16(); ip == nil {
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return nil, InvalidAddrError("non-IPv6 address")
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}
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s := new(syscall.SockaddrInet6)
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for i := 0; i < IPv6len; i++ {
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s.Addr[i] = ip[i]
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}
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s.Port = port
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return s, nil
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}
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return nil, InvalidAddrError("unexpected socket family")
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}
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// Split "host:port" into "host" and "port".
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// Host cannot contain colons unless it is bracketed.
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func splitHostPort(hostport string) (host, port string, err os.Error) {
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// The port starts after the last colon.
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i := last(hostport, ':')
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if i < 0 {
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err = &AddrError{"missing port in address", hostport}
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return
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}
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host, port = hostport[0:i], hostport[i+1:]
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// Can put brackets around host ...
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if len(host) > 0 && host[0] == '[' && host[len(host)-1] == ']' {
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host = host[1 : len(host)-1]
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} else {
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// ... but if there are no brackets, no colons.
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if byteIndex(host, ':') >= 0 {
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err = &AddrError{"too many colons in address", hostport}
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return
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}
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}
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return
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}
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// Join "host" and "port" into "host:port".
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// If host contains colons, will join into "[host]:port".
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func joinHostPort(host, port string) string {
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// If host has colons, have to bracket it.
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if byteIndex(host, ':') >= 0 {
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return "[" + host + "]:" + port
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}
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return host + ":" + port
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}
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// Convert "host:port" into IP address and port.
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func hostPortToIP(net, hostport string) (ip IP, iport int, err os.Error) {
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host, port, err := splitHostPort(hostport)
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if err != nil {
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goto Error
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}
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var addr IP
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if host != "" {
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// Try as an IP address.
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addr = ParseIP(host)
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if addr == nil {
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// Not an IP address. Try as a DNS name.
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_, addrs, err1 := LookupHost(host)
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if err1 != nil {
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err = err1
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goto Error
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}
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addr = ParseIP(addrs[0])
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if addr == nil {
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// should not happen
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err = &AddrError{"LookupHost returned invalid address", addrs[0]}
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goto Error
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}
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}
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}
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p, i, ok := dtoi(port, 0)
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if !ok || i != len(port) {
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p, err = LookupPort(net, port)
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if err != nil {
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goto Error
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}
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}
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if p < 0 || p > 0xFFFF {
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err = &AddrError{"invalid port", port}
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goto Error
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}
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return addr, p, nil
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Error:
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return nil, 0, err
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}
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