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.
 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
 }

 // ListenerTCP is a TCP network listener.
 // Clients should typically use variables of type Listener
 // instead of assuming TCP.
 type ListenerTCP struct {
 	fd *netFD;
 }

 // ListenTCP announces on the TCP address laddr and returns a TCP listener.
 // Net must be "tcp", "tcp4", or "tcp6".
 // If laddr has a port of 0, it means to listen on some available port.
 // The caller can use l.Addr() to retrieve the chosen address.
 func ListenTCP(net, laddr string) (l *ListenerTCP, err os.Error) {
 	fd, e := internetSocket(net, laddr, "", syscall.SOCK_STREAM, "listen");
 	if e != nil {
 		return nil, e
 	}
 	e1 := syscall.Listen(fd.fd, listenBacklog());
 	if e1 != 0 {
 		syscall.Close(fd.fd);
 		return nil, &OpError{"listen", "tcp", laddr, os.Errno(e1)};
 	}
 	l = new(ListenerTCP);
 	l.fd = fd;
 	return l, nil
 }

 // AcceptTCP accepts the next incoming call and returns the new connection
 // and the remote address.
 func (l *ListenerTCP) AcceptTCP() (c *ConnTCP, raddr string, err os.Error) {
 	if l == nil || l.fd == nil || l.fd.fd < 0 {
 		return nil, "", os.EINVAL
 	}
 	fd, e := l.fd.accept();
 	if e != nil {
 		return nil, "", e
 	}
 	return newConnTCP(fd, fd.raddr), fd.raddr, nil
 }

 // Accept implements the Accept method in the Listener interface;
 // it waits for the next call and returns a generic Conn.
 func (l *ListenerTCP) Accept() (c Conn, raddr string, err os.Error) {
 	c1, r1, e1 := l.AcceptTCP();
 	if e1 != nil {
 		return nil, "", e1
 	}
 	return c1, r1, nil
 }

 // Close stops listening on the TCP address.
 // Already Accepted connections are not closed.
 func (l *ListenerTCP) Close() os.Error {
 	if l == nil || l.fd == nil {
 		return os.EINVAL
 	}
 	return l.fd.Close()
 }

 // Addr returns the listener's network address.
 func (l *ListenerTCP) Addr() string {
 	return l.fd.addr();
 }

 // Internet sockets (TCP, UDP)

 func internetSocket(net, laddr, raddr string, proto int, mode string) (fd *netFD, err os.Error) {
 	// Parse addresses (unless they are empty).
 	var lip, rip IP;
 	var lport, rport int;

 	if laddr != "" {
 		if lip, lport, err = hostPortToIP(net, laddr, mode); err != nil {
 			goto Error;
 		}
 	}
 	if raddr != "" {
 		if rip, rport, err = hostPortToIP(net, raddr, mode); err != nil {
 			goto Error;
 		}
 	}

 	// Figure out IP version.
 	// If network has a suffix like "tcp4", obey it.
 	vers := 0;
 	switch net[len(net)-1] {
 	case '4':
 		vers = 4;
 	case '6':
 		vers = 6;
 	default:
 		// Otherwise, guess.
 		// If the addresses are IPv4 and we prefer IPv4, use 4; else 6.
 		if preferIPv4 && (lip == nil || lip.To4() != nil) && (rip == nil || rip.To4() != nil) {
 			vers = 4
 		} else {
 			vers = 6
 		}
 	}

 	var family int;
 	if vers == 4 {
 		family = syscall.AF_INET
 	} else {
 		family = syscall.AF_INET6
 	}

 	var la, ra syscall.Sockaddr;
 	if lip != nil {
 		if la, err = ipToSockaddr(family, lip, lport); err != nil {
 			goto Error;
 		}
 	}
 	if rip != nil {
 		if ra, err = ipToSockaddr(family, rip, rport); err != nil {
 			goto Error;
 		}
 	}

 	fd, err = socket(net, laddr, raddr, family, proto, 0, la, ra);
 	if err != nil {
 		goto Error;
 	}
 	return fd, nil;

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


 // TCP connections.

 // ConnTCP is an implementation of the Conn interface
 // for TCP network connections.
 type ConnTCP struct {
 	connBase
 }

 func (c *ConnTCP) SetNoDelay(nodelay bool) os.Error {
 	if c == nil {
 		return os.EINVAL
 	}
 	return setsockoptInt(c.sysFD(), syscall.IPPROTO_TCP, syscall.TCP_NODELAY, boolint(nodelay))
 }

 func newConnTCP(fd *netFD, raddr string) *ConnTCP {
 	c := new(ConnTCP);
 	c.fd = fd;
 	c.raddr = raddr;
 	c.SetNoDelay(true);
 	return c
 }

 // DialTCP is like Dial but can only connect to TCP networks
 // and returns a ConnTCP structure.
 func DialTCP(net, laddr, raddr string) (c *ConnTCP, err os.Error) {
 	if raddr == "" {
 		return nil, &OpError{"dial", "tcp", "", errMissingAddress}
 	}
 	fd, e := internetSocket(net, laddr, raddr, syscall.SOCK_STREAM, "dial");
 	if e != nil {
 		return nil, e
 	}
 	return newConnTCP(fd, raddr), nil
 }


 // UDP connections.

 // TODO(rsc): UDP headers mode

 // ConnUDP is an implementation of the Conn interface
 // for UDP network connections.
 type ConnUDP struct {
 	connBase
 }

 func newConnUDP(fd *netFD, raddr string) *ConnUDP {
 	c := new(ConnUDP);
 	c.fd = fd;
 	c.raddr = raddr;
 	return c
 }

 // DialUDP is like Dial but can only connect to UDP networks
 // and returns a ConnUDP structure.
 func DialUDP(net, laddr, raddr string) (c *ConnUDP, err os.Error) {
 	if raddr == "" {
 		return nil, &OpError{"dial", "udp", "", errMissingAddress}
 	}
 	fd, e := internetSocket(net, laddr, raddr, syscall.SOCK_DGRAM, "dial");
 	if e != nil {
 		return nil, e
 	}
 	return newConnUDP(fd, raddr), nil
 }

 func ipToSockaddr(family int, ip IP, port int) (syscall.Sockaddr, os.Error) {
 	switch family {
 	case syscall.AF_INET:
 		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:
 		// 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.
 // For now, host and port must be numeric literals.
 // Eventually, we'll have name resolution.
 func hostPortToIP(net, hostport, mode string) (ip IP, iport int, err os.Error) {
 	host, port, err := splitHostPort(hostport);
 	if err != nil {
 		goto Error;
 	}

 	var addr IP;
 	if host == "" {
 		if mode != "listen" {
 			err = &AddrError{"no host in address", hostport};
 			goto Error;
 		}
 		if preferIPv4 {
 			addr = IPv4zero;
 		} else {
 			addr = IPzero;	// wildcard - listen to all
 		}
 	}

 	// Try as an IP address.
 	if addr == nil {
 		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;
 }
	// 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
	}

	// ListenerTCP is a TCP network listener.
	// Clients should typically use variables of type Listener
	// instead of assuming TCP.
	type ListenerTCP struct {
	fd *netFD;
	}

	// ListenTCP announces on the TCP address laddr and returns a TCP listener.
	// Net must be "tcp", "tcp4", or "tcp6".
	// If laddr has a port of 0, it means to listen on some available port.
	// The caller can use l.Addr() to retrieve the chosen address.
	func ListenTCP(net, laddr string) (l *ListenerTCP, err os.Error) {
	fd, e := internetSocket(net, laddr, "", syscall.SOCK_STREAM, "listen");
	if e != nil {
	return nil, e
	}
	e1 := syscall.Listen(fd.fd, listenBacklog());
	if e1 != 0 {
	syscall.Close(fd.fd);
	return nil, &OpError{"listen", "tcp", laddr, os.Errno(e1)};
	}
	l = new(ListenerTCP);
	l.fd = fd;
	return l, nil
	}

	// AcceptTCP accepts the next incoming call and returns the new connection
	// and the remote address.
	func (l ListenerTCP) AcceptTCP() (c ConnTCP, raddr string, err os.Error) {
	if l == nil \|\| l.fd == nil \|\| l.fd.fd < 0 {
	return nil, "", os.EINVAL
	}
	fd, e := l.fd.accept();
	if e != nil {
	return nil, "", e
	}
	return newConnTCP(fd, fd.raddr), fd.raddr, nil
	}

	// Accept implements the Accept method in the Listener interface;
	// it waits for the next call and returns a generic Conn.
	func (l *ListenerTCP) Accept() (c Conn, raddr string, err os.Error) {
	c1, r1, e1 := l.AcceptTCP();
	if e1 != nil {
	return nil, "", e1
	}
	return c1, r1, nil
	}

	// Close stops listening on the TCP address.
	// Already Accepted connections are not closed.
	func (l *ListenerTCP) Close() os.Error {
	if l == nil \|\| l.fd == nil {
	return os.EINVAL
	}
	return l.fd.Close()
	}

	// Addr returns the listener's network address.
	func (l *ListenerTCP) Addr() string {
	return l.fd.addr();
	}

	// Internet sockets (TCP, UDP)

	func internetSocket(net, laddr, raddr string, proto int, mode string) (fd *netFD, err os.Error) {
	// Parse addresses (unless they are empty).
	var lip, rip IP;
	var lport, rport int;

	if laddr != "" {
	if lip, lport, err = hostPortToIP(net, laddr, mode); err != nil {
	goto Error;
	}
	}
	if raddr != "" {
	if rip, rport, err = hostPortToIP(net, raddr, mode); err != nil {
	goto Error;
	}
	}

	// Figure out IP version.
	// If network has a suffix like "tcp4", obey it.
	vers := 0;
	switch net[len(net)-1] {
	case '4':
	vers = 4;
	case '6':
	vers = 6;
	default:
	// Otherwise, guess.
	// If the addresses are IPv4 and we prefer IPv4, use 4; else 6.
	if preferIPv4 && (lip == nil \|\| lip.To4() != nil) && (rip == nil \|\| rip.To4() != nil) {
	vers = 4
	} else {
	vers = 6
	}
	}

	var family int;
	if vers == 4 {
	family = syscall.AF_INET
	} else {
	family = syscall.AF_INET6
	}

	var la, ra syscall.Sockaddr;
	if lip != nil {
	if la, err = ipToSockaddr(family, lip, lport); err != nil {
	goto Error;
	}
	}
	if rip != nil {
	if ra, err = ipToSockaddr(family, rip, rport); err != nil {
	goto Error;
	}
	}

	fd, err = socket(net, laddr, raddr, family, proto, 0, la, ra);
	if err != nil {
	goto Error;
	}
	return fd, nil;

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


	// TCP connections.

	// ConnTCP is an implementation of the Conn interface
	// for TCP network connections.
	type ConnTCP struct {
	connBase
	}

	func (c *ConnTCP) SetNoDelay(nodelay bool) os.Error {
	if c == nil {
	return os.EINVAL
	}
	return setsockoptInt(c.sysFD(), syscall.IPPROTO_TCP, syscall.TCP_NODELAY, boolint(nodelay))
	}

	func newConnTCP(fd netFD, raddr string) ConnTCP {
	c := new(ConnTCP);
	c.fd = fd;
	c.raddr = raddr;
	c.SetNoDelay(true);
	return c
	}

	// DialTCP is like Dial but can only connect to TCP networks
	// and returns a ConnTCP structure.
	func DialTCP(net, laddr, raddr string) (c *ConnTCP, err os.Error) {
	if raddr == "" {
	return nil, &OpError{"dial", "tcp", "", errMissingAddress}
	}
	fd, e := internetSocket(net, laddr, raddr, syscall.SOCK_STREAM, "dial");
	if e != nil {
	return nil, e
	}
	return newConnTCP(fd, raddr), nil
	}


	// UDP connections.

	// TODO(rsc): UDP headers mode

	// ConnUDP is an implementation of the Conn interface
	// for UDP network connections.
	type ConnUDP struct {
	connBase
	}

	func newConnUDP(fd netFD, raddr string) ConnUDP {
	c := new(ConnUDP);
	c.fd = fd;
	c.raddr = raddr;
	return c
	}

	// DialUDP is like Dial but can only connect to UDP networks
	// and returns a ConnUDP structure.
	func DialUDP(net, laddr, raddr string) (c *ConnUDP, err os.Error) {
	if raddr == "" {
	return nil, &OpError{"dial", "udp", "", errMissingAddress}
	}
	fd, e := internetSocket(net, laddr, raddr, syscall.SOCK_DGRAM, "dial");
	if e != nil {
	return nil, e
	}
	return newConnUDP(fd, raddr), nil
	}

	func ipToSockaddr(family int, ip IP, port int) (syscall.Sockaddr, os.Error) {
	switch family {
	case syscall.AF_INET:
	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:
	// 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.
	// For now, host and port must be numeric literals.
	// Eventually, we'll have name resolution.
	func hostPortToIP(net, hostport, mode string) (ip IP, iport int, err os.Error) {
	host, port, err := splitHostPort(hostport);
	if err != nil {
	goto Error;
	}

	var addr IP;
	if host == "" {
	if mode != "listen" {
	err = &AddrError{"no host in address", hostport};
	goto Error;
	}
	if preferIPv4 {
	addr = IPv4zero;
	} else {
	addr = IPzero; // wildcard - listen to all
	}
	}

	// Try as an IP address.
	if addr == nil {
	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;
	}