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