1 // Copyright 2009 The Go Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style
3 // license that can be found in the LICENSE file.
14 // Should we try to use the IPv4 socket interface if we're
15 // only dealing with IPv4 sockets? As long as the host system
16 // understands IPv6, it's okay to pass IPv4 addresses to the IPv6
17 // interface. That simplifies our code and is most general.
18 // Unfortunately, we need to run on kernels built without IPv6 support too.
19 // So probe the kernel to figure it out.
20 func kernelSupportsIPv6() bool {
21 s, err := syscall.Socket(syscall.AF_INET6, syscall.SOCK_STREAM, syscall.IPPROTO_TCP)
27 la := &TCPAddr{IP: IPv4(127, 0, 0, 1)}
28 sa, oserr := la.toAddr().sockaddr(syscall.AF_INET6)
33 return syscall.Bind(s, sa) == 0
36 var preferIPv4 = !kernelSupportsIPv6()
38 func firstSupportedAddr(addrs []string) (addr IP) {
39 for _, s := range addrs {
41 if !preferIPv4 || addr.To4() != nil {
49 // TODO(rsc): if syscall.OS == "linux", we're supposd to read
50 // /proc/sys/net/core/somaxconn,
51 // to take advantage of kernels that have raised the limit.
52 func listenBacklog() int { return syscall.SOMAXCONN }
54 // Internet sockets (TCP, UDP)
56 // A sockaddr represents a TCP or UDP network address that can
57 // be converted into a syscall.Sockaddr.
58 type sockaddr interface {
60 sockaddr(family int) (syscall.Sockaddr, os.Error)
64 func internetSocket(net string, laddr, raddr sockaddr, socktype, proto int, mode string, toAddr func(syscall.Sockaddr) Addr) (fd *netFD, err os.Error) {
65 // Figure out IP version.
66 // If network has a suffix like "tcp4", obey it.
68 family := syscall.AF_INET6
69 switch net[len(net)-1] {
71 family = syscall.AF_INET
76 // If the addresses are IPv4 and we prefer IPv4, use 4; else 6.
78 (laddr == nil || laddr.family() == syscall.AF_INET) &&
79 (raddr == nil || raddr.family() == syscall.AF_INET) {
80 family = syscall.AF_INET
84 var la, ra syscall.Sockaddr
86 if la, oserr = laddr.sockaddr(family); oserr != nil {
91 if ra, oserr = raddr.sockaddr(family); oserr != nil {
95 fd, oserr = socket(net, family, socktype, proto, la, ra, toAddr)
103 if mode == "listen" {
106 return nil, &OpError{mode, net, addr, oserr}
109 func getip(fd int, remote bool) (ip []byte, port int, ok bool) {
110 // No attempt at error reporting because
111 // there are no possible errors, and the
112 // caller won't report them anyway.
113 var sa syscall.Sockaddr
115 sa, _ = syscall.Getpeername(fd)
117 sa, _ = syscall.Getsockname(fd)
119 switch sa := sa.(type) {
120 case *syscall.SockaddrInet4:
121 return sa.Addr[0:], sa.Port, true
122 case *syscall.SockaddrInet6:
123 return sa.Addr[0:], sa.Port, true
128 type InvalidAddrError string
130 func (e InvalidAddrError) String() string { return string(e) }
131 func (e InvalidAddrError) Timeout() bool { return false }
132 func (e InvalidAddrError) Temporary() bool { return false }
135 func ipToSockaddr(family int, ip IP, port int) (syscall.Sockaddr, os.Error) {
137 case syscall.AF_INET:
141 if ip = ip.To4(); ip == nil {
142 return nil, InvalidAddrError("non-IPv4 address")
144 s := new(syscall.SockaddrInet4)
145 for i := 0; i < IPv4len; i++ {
150 case syscall.AF_INET6:
154 // IPv4 callers use 0.0.0.0 to mean "announce on any available address".
155 // In IPv6 mode, Linux treats that as meaning "announce on 0.0.0.0",
156 // which it refuses to do. Rewrite to the IPv6 all zeros.
157 if p4 := ip.To4(); p4 != nil && p4[0] == 0 && p4[1] == 0 && p4[2] == 0 && p4[3] == 0 {
160 if ip = ip.To16(); ip == nil {
161 return nil, InvalidAddrError("non-IPv6 address")
163 s := new(syscall.SockaddrInet6)
164 for i := 0; i < IPv6len; i++ {
170 return nil, InvalidAddrError("unexpected socket family")
173 // Split "host:port" into "host" and "port".
174 // Host cannot contain colons unless it is bracketed.
175 func splitHostPort(hostport string) (host, port string, err os.Error) {
176 // The port starts after the last colon.
177 i := last(hostport, ':')
179 err = &AddrError{"missing port in address", hostport}
183 host, port = hostport[0:i], hostport[i+1:]
185 // Can put brackets around host ...
186 if len(host) > 0 && host[0] == '[' && host[len(host)-1] == ']' {
187 host = host[1 : len(host)-1]
189 // ... but if there are no brackets, no colons.
190 if byteIndex(host, ':') >= 0 {
191 err = &AddrError{"too many colons in address", hostport}
198 // Join "host" and "port" into "host:port".
199 // If host contains colons, will join into "[host]:port".
200 func joinHostPort(host, port string) string {
201 // If host has colons, have to bracket it.
202 if byteIndex(host, ':') >= 0 {
203 return "[" + host + "]:" + port
205 return host + ":" + port
208 // Convert "host:port" into IP address and port.
209 func hostPortToIP(net, hostport string) (ip IP, iport int, err os.Error) {
210 host, port, err := splitHostPort(hostport)
217 // Try as an IP address.
220 // Not an IP address. Try as a DNS name.
221 _, addrs, err1 := LookupHost(host)
226 addr = firstSupportedAddr(addrs)
229 err = &AddrError{"LookupHost returned invalid address", addrs[0]}
235 p, i, ok := dtoi(port, 0)
236 if !ok || i != len(port) {
237 p, err = LookupPort(net, port)
242 if p < 0 || p > 0xFFFF {
243 err = &AddrError{"invalid port", port}