src/pkg/net/ipsock.go - go - Git at Google

 // 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.
 //
 // probeIPv6Stack probes both basic IPv6 capability and IPv6 IPv4-
 // mapping capability which is controlled by IPV6_V6ONLY socket
 // option and/or kernel state "net.inet6.ip6.v6only".
 // It returns two boolean values.  If the first boolean value is
 // true, kernel supports basic IPv6 functionality.  If the second
 // boolean value is true, kernel supports IPv6 IPv4-mapping.
 func probeIPv6Stack() (supportsIPv6, supportsIPv4map bool) {
 	var probes = []struct {
 		s  int
 		la TCPAddr
 		ok bool
 	}{
 		// IPv6 communication capability
 		{-1, TCPAddr{IP: ParseIP("::1")}, false},
 		// IPv6 IPv4-mapped address communication capability
 		{-1, TCPAddr{IP: IPv4(127, 0, 0, 1)}, false},
 	}
 	var errno int

 	for i := range probes {
 		probes[i].s, errno = syscall.Socket(syscall.AF_INET6, syscall.SOCK_STREAM, syscall.IPPROTO_TCP)
 		if errno != 0 {
 			continue
 		}
 		defer closesocket(probes[i].s)
 		sa, err := probes[i].la.toAddr().sockaddr(syscall.AF_INET6)
 		if err != nil {
 			continue
 		}
 		errno = syscall.Bind(probes[i].s, sa)
 		if errno != 0 {
 			continue
 		}
 		probes[i].ok = true
 	}

 	return probes[0].ok, probes[1].ok
 }

 var supportsIPv6, supportsIPv4map = probeIPv6Stack()

 // favoriteAddrFamily returns the appropriate address family to
 // the given net, raddr, laddr and mode.  At first it figures
 // address family out from the net.  If mode indicates "listen"
 // and laddr.(type).IP is nil, it assumes that the user wants to
 // make a passive connection with wildcard address family, both
 // INET and INET6, and wildcard address.  Otherwise guess: if the
 // addresses are IPv4 then returns INET, or else returns INET6.
 func favoriteAddrFamily(net string, raddr, laddr sockaddr, mode string) int {
 	switch net[len(net)-1] {
 	case '4':
 		return syscall.AF_INET
 	case '6':
 		return syscall.AF_INET6
 	}

 	if mode == "listen" {
 		switch a := laddr.(type) {
 		case *TCPAddr:
 			if a.IP == nil && supportsIPv6 {
 				return syscall.AF_INET6
 			}
 		case *UDPAddr:
 			if a.IP == nil && supportsIPv6 {
 				return syscall.AF_INET6
 			}
 		case *IPAddr:
 			if a.IP == nil && supportsIPv6 {
 				return syscall.AF_INET6
 			}
 		}
 	}

 	if (laddr == nil || laddr.family() == syscall.AF_INET) &&
 		(raddr == nil || raddr.family() == syscall.AF_INET) {
 		return syscall.AF_INET
 	}
 	return syscall.AF_INET6
 }

 func firstFavoriteAddr(filter func(IP) IP, addrs []string) (addr IP) {
 	if filter == anyaddr {
 		// We'll take any IP address, but since the dialing code
 		// does not yet try multiple addresses, prefer to use
 		// an IPv4 address if possible.  This is especially relevant
 		// if localhost resolves to [ipv6-localhost, ipv4-localhost].
 		// Too much code assumes localhost == ipv4-localhost.
 		addr = firstSupportedAddr(ipv4only, addrs)
 		if addr == nil {
 			addr = firstSupportedAddr(anyaddr, addrs)
 		}
 	} else {
 		addr = firstSupportedAddr(filter, addrs)
 	}
 	return
 }

 func firstSupportedAddr(filter func(IP) IP, addrs []string) IP {
 	for _, s := range addrs {
 		if addr := filter(ParseIP(s)); addr != nil {
 			return addr
 		}
 	}
 	return nil
 }

 func anyaddr(x IP) IP {
 	if x4 := x.To4(); x4 != nil {
 		return x4
 	}
 	if supportsIPv6 {
 		return x
 	}
 	return nil
 }

 func ipv4only(x IP) IP { return x.To4() }

 func ipv6only(x IP) IP {
 	// Only return addresses that we can use
 	// with the kernel's IPv6 addressing modes.
 	if len(x) == IPv6len && x.To4() == nil && supportsIPv6 {
 		return x
 	}
 	return nil
 }

 // TODO(rsc): if syscall.OS == "linux", we're supposed 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, socktype, proto int, mode string, toAddr func(syscall.Sockaddr) Addr) (fd *netFD, err os.Error) {
 	var oserr os.Error
 	var la, ra syscall.Sockaddr
 	family := favoriteAddrFamily(net, raddr, laddr, mode)
 	if laddr != nil {
 		if la, oserr = laddr.sockaddr(family); oserr != nil {
 			goto Error
 		}
 	}
 	if raddr != nil {
 		if ra, oserr = raddr.sockaddr(family); oserr != nil {
 			goto Error
 		}
 	}
 	fd, oserr = socket(net, family, socktype, proto, la, ra, toAddr)
 	if oserr != nil {
 		goto Error
 	}
 	return fd, nil

 Error:
 	addr := raddr
 	if mode == "listen" {
 		addr = laddr
 	}
 	return nil, &OpError{mode, net, addr, oserr}
 }

 type InvalidAddrError string

 func (e InvalidAddrError) String() string  { return string(e) }
 func (e InvalidAddrError) Timeout() bool   { return false }
 func (e InvalidAddrError) Temporary() bool { return false }

 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, InvalidAddrError("non-IPv4 address")
 		}
 		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 = IPv6zero
 		}
 		// 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 ip.Equal(IPv4zero) {
 			ip = IPv6zero
 		}
 		if ip = ip.To16(); ip == nil {
 			return nil, InvalidAddrError("non-IPv6 address")
 		}
 		s := new(syscall.SockaddrInet6)
 		for i := 0; i < IPv6len; i++ {
 			s.Addr[i] = ip[i]
 		}
 		s.Port = port
 		return s, nil
 	}
 	return nil, InvalidAddrError("unexpected socket family")
 }

 // SplitHostPort splits a network address of the form
 // "host:port" or "[host]:port" into host and port.
 // The latter form must be used when host contains a colon.
 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:]

 	// 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
 }

 // JoinHostPort combines host and port into a network address
 // of the form "host:port" or, if host contains a colon, "[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) {
 	var (
 		addr IP
 		p, i int
 		ok   bool
 	)
 	host, port, err := SplitHostPort(hostport)
 	if err != nil {
 		goto Error
 	}

 	if host != "" {
 		// Try as an IP address.
 		addr = ParseIP(host)
 		if addr == nil {
 			filter := anyaddr
 			if net != "" && net[len(net)-1] == '4' {
 				filter = ipv4only
 			}
 			if net != "" && net[len(net)-1] == '6' {
 				filter = ipv6only
 			}
 			// Not an IP address.  Try as a DNS name.
 			addrs, err1 := LookupHost(host)
 			if err1 != nil {
 				err = err1
 				goto Error
 			}
 			addr = firstFavoriteAddr(filter, addrs)
 			if addr == nil {
 				// should not happen
 				err = &AddrError{"LookupHost returned no suitable 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
 }
	// 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.
	//
	// probeIPv6Stack probes both basic IPv6 capability and IPv6 IPv4-
	// mapping capability which is controlled by IPV6_V6ONLY socket
	// option and/or kernel state "net.inet6.ip6.v6only".
	// It returns two boolean values. If the first boolean value is
	// true, kernel supports basic IPv6 functionality. If the second
	// boolean value is true, kernel supports IPv6 IPv4-mapping.
	func probeIPv6Stack() (supportsIPv6, supportsIPv4map bool) {
	var probes = []struct {
	s int
	la TCPAddr
	ok bool
	}{
	// IPv6 communication capability
	{-1, TCPAddr{IP: ParseIP("::1")}, false},
	// IPv6 IPv4-mapped address communication capability
	{-1, TCPAddr{IP: IPv4(127, 0, 0, 1)}, false},
	}
	var errno int

	for i := range probes {
	probes[i].s, errno = syscall.Socket(syscall.AF_INET6, syscall.SOCK_STREAM, syscall.IPPROTO_TCP)
	if errno != 0 {
	continue
	}
	defer closesocket(probes[i].s)
	sa, err := probes[i].la.toAddr().sockaddr(syscall.AF_INET6)
	if err != nil {
	continue
	}
	errno = syscall.Bind(probes[i].s, sa)
	if errno != 0 {
	continue
	}
	probes[i].ok = true
	}

	return probes[0].ok, probes[1].ok
	}

	var supportsIPv6, supportsIPv4map = probeIPv6Stack()

	// favoriteAddrFamily returns the appropriate address family to
	// the given net, raddr, laddr and mode. At first it figures
	// address family out from the net. If mode indicates "listen"
	// and laddr.(type).IP is nil, it assumes that the user wants to
	// make a passive connection with wildcard address family, both
	// INET and INET6, and wildcard address. Otherwise guess: if the
	// addresses are IPv4 then returns INET, or else returns INET6.
	func favoriteAddrFamily(net string, raddr, laddr sockaddr, mode string) int {
	switch net[len(net)-1] {
	case '4':
	return syscall.AF_INET
	case '6':
	return syscall.AF_INET6
	}

	if mode == "listen" {
	switch a := laddr.(type) {
	case *TCPAddr:
	if a.IP == nil && supportsIPv6 {
	return syscall.AF_INET6
	}
	case *UDPAddr:
	if a.IP == nil && supportsIPv6 {
	return syscall.AF_INET6
	}
	case *IPAddr:
	if a.IP == nil && supportsIPv6 {
	return syscall.AF_INET6
	}
	}
	}

	if (laddr == nil \|\| laddr.family() == syscall.AF_INET) &&
	(raddr == nil \|\| raddr.family() == syscall.AF_INET) {
	return syscall.AF_INET
	}
	return syscall.AF_INET6
	}

	func firstFavoriteAddr(filter func(IP) IP, addrs []string) (addr IP) {
	if filter == anyaddr {
	// We'll take any IP address, but since the dialing code
	// does not yet try multiple addresses, prefer to use
	// an IPv4 address if possible. This is especially relevant
	// if localhost resolves to [ipv6-localhost, ipv4-localhost].
	// Too much code assumes localhost == ipv4-localhost.
	addr = firstSupportedAddr(ipv4only, addrs)
	if addr == nil {
	addr = firstSupportedAddr(anyaddr, addrs)
	}
	} else {
	addr = firstSupportedAddr(filter, addrs)
	}
	return
	}

	func firstSupportedAddr(filter func(IP) IP, addrs []string) IP {
	for _, s := range addrs {
	if addr := filter(ParseIP(s)); addr != nil {
	return addr
	}
	}
	return nil
	}

	func anyaddr(x IP) IP {
	if x4 := x.To4(); x4 != nil {
	return x4
	}
	if supportsIPv6 {
	return x
	}
	return nil
	}

	func ipv4only(x IP) IP { return x.To4() }

	func ipv6only(x IP) IP {
	// Only return addresses that we can use
	// with the kernel's IPv6 addressing modes.
	if len(x) == IPv6len && x.To4() == nil && supportsIPv6 {
	return x
	}
	return nil
	}

	// TODO(rsc): if syscall.OS == "linux", we're supposed 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, socktype, proto int, mode string, toAddr func(syscall.Sockaddr) Addr) (fd *netFD, err os.Error) {
	var oserr os.Error
	var la, ra syscall.Sockaddr
	family := favoriteAddrFamily(net, raddr, laddr, mode)
	if laddr != nil {
	if la, oserr = laddr.sockaddr(family); oserr != nil {
	goto Error
	}
	}
	if raddr != nil {
	if ra, oserr = raddr.sockaddr(family); oserr != nil {
	goto Error
	}
	}
	fd, oserr = socket(net, family, socktype, proto, la, ra, toAddr)
	if oserr != nil {
	goto Error
	}
	return fd, nil

	Error:
	addr := raddr
	if mode == "listen" {
	addr = laddr
	}
	return nil, &OpError{mode, net, addr, oserr}
	}

	type InvalidAddrError string

	func (e InvalidAddrError) String() string { return string(e) }
	func (e InvalidAddrError) Timeout() bool { return false }
	func (e InvalidAddrError) Temporary() bool { return false }

	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, InvalidAddrError("non-IPv4 address")
	}
	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 = IPv6zero
	}
	// 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 ip.Equal(IPv4zero) {
	ip = IPv6zero
	}
	if ip = ip.To16(); ip == nil {
	return nil, InvalidAddrError("non-IPv6 address")
	}
	s := new(syscall.SockaddrInet6)
	for i := 0; i < IPv6len; i++ {
	s.Addr[i] = ip[i]
	}
	s.Port = port
	return s, nil
	}
	return nil, InvalidAddrError("unexpected socket family")
	}

	// SplitHostPort splits a network address of the form
	// "host:port" or "[host]:port" into host and port.
	// The latter form must be used when host contains a colon.
	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:]

	// 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
	}

	// JoinHostPort combines host and port into a network address
	// of the form "host:port" or, if host contains a colon, "[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) {
	var (
	addr IP
	p, i int
	ok bool
	)
	host, port, err := SplitHostPort(hostport)
	if err != nil {
	goto Error
	}

	if host != "" {
	// Try as an IP address.
	addr = ParseIP(host)
	if addr == nil {
	filter := anyaddr
	if net != "" && net[len(net)-1] == '4' {
	filter = ipv4only
	}
	if net != "" && net[len(net)-1] == '6' {
	filter = ipv6only
	}
	// Not an IP address. Try as a DNS name.
	addrs, err1 := LookupHost(host)
	if err1 != nil {
	err = err1
	goto Error
	}
	addr = firstFavoriteAddr(filter, addrs)
	if addr == nil {
	// should not happen
	err = &AddrError{"LookupHost returned no suitable 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
	}