split ipsock.go, sock.go, and unixsock.go out of net.go

prior to cleanup.  no changes, only moving.

remove dependencies on strconv and strings

R=r
http://go/go-review/1017010

src/pkg/Make.deps

@@ -5,8 +5,8 @@ bignum.install: fmt.install
 bufio.install: io.install os.install strconv.install utf8.install
 bytes.install: os.install unicode.install utf8.install
 compress/flate.install: bufio.install bytes.install io.install math.install os.install sort.install strconv.install
-compress/gzip.install: bufio.install compress/flate.install hash/crc32.install hash.install io.install os.install
-compress/zlib.install: bufio.install compress/flate.install hash/adler32.install hash.install io.install os.install
+compress/gzip.install: bufio.install compress/flate.install hash.install hash/crc32.install io.install os.install
+compress/zlib.install: bufio.install compress/flate.install hash.install hash/adler32.install io.install os.install
 container/heap.install: sort.install
 container/list.install:
 container/ring.install:
@@ -19,7 +19,7 @@ crypto/rc4.install: os.install strconv.install
 crypto/sha1.install: hash.install os.install
 debug/dwarf.install: encoding/binary.install os.install strconv.install
 debug/macho.install: bytes.install debug/dwarf.install encoding/binary.install fmt.install io.install os.install strconv.install
-debug/elf.install: bytes.install debug/dwarf.install encoding/binary.install fmt.install io.install os.install strconv.install
+debug/elf.install: debug/dwarf.install encoding/binary.install fmt.install io.install os.install strconv.install
 debug/gosym.install: encoding/binary.install fmt.install os.install strconv.install strings.install
 debug/proc.install: container/vector.install fmt.install io.install os.install runtime.install strconv.install strings.install sync.install syscall.install
 ebnf.install: container/vector.install go/scanner.install go/token.install os.install strconv.install unicode.install utf8.install
@@ -47,13 +47,13 @@ hash/adler32.install: hash.install os.install
 hash/crc32.install: hash.install os.install
 http.install: bufio.install bytes.install container/vector.install fmt.install io.install log.install net.install os.install path.install strconv.install strings.install utf8.install
 image.install:
-image/png.install: bufio.install compress/zlib.install hash/crc32.install hash.install image.install io.install os.install strconv.install
+image/png.install: bufio.install compress/zlib.install hash.install hash/crc32.install image.install io.install os.install strconv.install
 io.install: bytes.install os.install sort.install strings.install sync.install
 json.install: bytes.install container/vector.install fmt.install math.install reflect.install strconv.install strings.install utf8.install
 log.install: fmt.install io.install os.install runtime.install time.install
 malloc.install:
 math.install:
-net.install: fmt.install io.install once.install os.install reflect.install strconv.install strings.install sync.install syscall.install
+net.install: fmt.install io.install once.install os.install reflect.install sync.install syscall.install
 once.install: sync.install
 os.install: once.install syscall.install
 path.install: io.install os.install strings.install
@@ -63,14 +63,13 @@ regexp.install: bytes.install container/vector.install io.install os.install run
 rpc.install: bufio.install fmt.install gob.install http.install io.install log.install net.install os.install reflect.install sort.install strings.install sync.install template.install unicode.install utf8.install
 runtime.install:
 sort.install:
-strconv.install: bytes.install math.install os.install unicode.install utf8.install
+strconv.install: bytes.install math.install os.install strings.install unicode.install utf8.install
 strings.install: os.install unicode.install utf8.install
 sync.install: runtime.install
 syscall.install: sync.install
 tabwriter.install: bytes.install container/vector.install io.install os.install utf8.install
 template.install: bytes.install container/vector.install fmt.install io.install os.install reflect.install runtime.install strings.install
 testing.install: flag.install fmt.install os.install runtime.install utf8.install
-testing/expect.install: fmt.install os.install rand.install reflect.install strings.install
 testing/iotest.install: bytes.install io.install log.install os.install
 testing/quick.install: flag.install fmt.install math.install os.install rand.install reflect.install strings.install
 time.install: io.install once.install os.install syscall.install

src/pkg/net/Makefile

@@ -12,8 +12,11 @@ GOFILES=\
 	fd.go\
 	fd_$(GOOS).go\
 	ip.go\
+	ipsock.go\
 	net.go\
 	parse.go\
 	port.go\
+	sock.go\
+	unixsock.go\
 
 include $(GOROOT)/src/Make.pkg

src/pkg/net/dnsclient.go

@@ -11,14 +11,12 @@
 //	Could have a small cache.
 //	Random UDP source port (net.Dial should do that for us).
 //	Random request IDs.
-//	More substantial error reporting.
 
 package net
 
 import (
 	"once";
 	"os";
-	"strings";
 )
 
 // DNSError represents a DNS lookup error.
@@ -240,7 +238,7 @@ func LookupHost(name string) (cname string, addrs []string, err os.Error) {
 	// If name is rooted (trailing dot) or has enough dots,
 	// try it by itself first.
 	rooted := len(name) > 0 && name[len(name)-1] == '.';
-	if rooted || strings.Count(name, ".") >= cfg.ndots {
+	if rooted || count(name, '.') >= cfg.ndots {
 		rname := name;
 		if !rooted {
 			rname += ".";

src/pkg/net/ip.go

@@ -12,9 +12,6 @@
 
 package net
 
-import (
-)
-
 // IP address lengths (bytes).
 const (
 	IPv4len = 4;

src/pkg/net/ipsock.go

+// 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;
+}
+

src/pkg/net/parse.go

@@ -3,7 +3,7 @@
 // license that can be found in the LICENSE file.
 
 // Simple file i/o and string manipulation, to avoid
-// depending on strconv and bufio.
+// depending on strconv and bufio and strings.
 
 package net
 
@@ -154,3 +154,46 @@ func xtoi(s string, i0 int) (n int, i int, ok bool) {
 	return n, i, true
 }
 
+// Integer to decimal.
+func itoa(i int) string {
+	var buf [30]byte;
+	n := len(buf);
+	neg := false;
+	if i < 0 {
+		i = -i;
+		neg = true;
+	}
+	ui := uint(i);
+	for ui > 0 || n == len(buf) {
+		n--;
+		buf[n] = byte('0' + ui%10);
+		ui /= 10;
+	}
+	if neg {
+		n--;
+		buf[n] = '-';
+	}
+	return string(buf[n:len(buf)]);
+}
+
+// Number of occurrences of b in s.
+func count(s string, b byte) int {
+	n := 0;
+	for i := 0; i < len(s); i++ {
+		if s[i] == b {
+			n++;
+		}
+	}
+	return n;
+}
+
+// Index of rightmost occurrence of b in s.
+func last(s string, b byte) int {
+	i := len(s);
+	for i--; i >= 0; i-- {
+		if s[i] == b {
+			break;
+		}
+	}
+	return i;
+}

src/pkg/net/sock.go

+// 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.
+
+// Sockets
+
+package net
+
+import (
+	"os";
+	"reflect";
+	"syscall";
+)
+
+// Boolean to int.
+func boolint(b bool) int {
+	if b {
+		return 1
+	}
+	return 0
+}
+
+// Generic socket creation.
+func socket(net, laddr, raddr string, f, p, t int, la, ra syscall.Sockaddr) (fd *netFD, err os.Error) {
+	// See ../syscall/exec.go for description of ForkLock.
+	syscall.ForkLock.RLock();
+	s, e := syscall.Socket(f, p, t);
+	if e != 0 {
+		syscall.ForkLock.RUnlock();
+		return nil, os.Errno(e)
+	}
+	syscall.CloseOnExec(s);
+	syscall.ForkLock.RUnlock();
+
+	// Allow reuse of recently-used addresses.
+	syscall.SetsockoptInt(s, syscall.SOL_SOCKET, syscall.SO_REUSEADDR, 1);
+
+	if la != nil {
+		e = syscall.Bind(s, la);
+		if e != 0 {
+			syscall.Close(s);
+			return nil, os.Errno(e)
+		}
+	}
+
+	if ra != nil {
+		e = syscall.Connect(s, ra);
+		if e != 0 {
+			syscall.Close(s);
+			return nil, os.Errno(e)
+		}
+	}
+
+	fd, err = newFD(s, net, laddr, raddr);
+	if err != nil {
+		syscall.Close(s);
+		return nil, err
+	}
+
+	return fd, nil
+}
+
+
+// Generic implementation of Conn interface; not exported.
+type connBase struct {
+	fd *netFD;
+	raddr string;
+}
+
+func (c *connBase) LocalAddr() string {
+	if c == nil {
+		return ""
+	}
+	return c.fd.addr();
+}
+
+func (c *connBase) RemoteAddr() string {
+	if c == nil {
+		return ""
+	}
+	return c.fd.remoteAddr();
+}
+
+func (c *connBase) File() *os.File {
+	if c == nil {
+		return nil
+	}
+	return c.fd.file;
+}
+
+func (c *connBase) sysFD() int {
+	if c == nil || c.fd == nil {
+		return -1;
+	}
+	return c.fd.fd;
+}
+
+func (c *connBase) Read(b []byte) (n int, err os.Error) {
+	n, err = c.fd.Read(b);
+	return n, err
+}
+
+func (c *connBase) Write(b []byte) (n int, err os.Error) {
+	n, err = c.fd.Write(b);
+	return n, err
+}
+
+func (c *connBase) ReadFrom(b []byte) (n int, raddr string, err os.Error) {
+	if c == nil {
+		return -1, "", os.EINVAL
+	}
+	n, err = c.Read(b);
+	return n, c.raddr, err
+}
+
+func (c *connBase) WriteTo(raddr string, b []byte) (n int, err os.Error) {
+	if c == nil {
+		return -1, os.EINVAL
+	}
+	if raddr != c.raddr {
+		return -1, os.EINVAL
+	}
+	n, err = c.Write(b);
+	return n, err
+}
+
+func (c *connBase) Close() os.Error {
+	if c == nil {
+		return os.EINVAL
+	}
+	return c.fd.Close()
+}
+
+
+func setsockoptInt(fd, level, opt int, value int) os.Error {
+	return os.NewSyscallError("setsockopt", syscall.SetsockoptInt(fd, level, opt, value));
+}
+
+func setsockoptNsec(fd, level, opt int, nsec int64) os.Error {
+	var tv = syscall.NsecToTimeval(nsec);
+	return os.NewSyscallError("setsockopt", syscall.SetsockoptTimeval(fd, level, opt, &tv));
+}
+
+func (c *connBase) SetReadBuffer(bytes int) os.Error {
+	return setsockoptInt(c.sysFD(), syscall.SOL_SOCKET, syscall.SO_RCVBUF, bytes);
+}
+
+func (c *connBase) SetWriteBuffer(bytes int) os.Error {
+	return setsockoptInt(c.sysFD(), syscall.SOL_SOCKET, syscall.SO_SNDBUF, bytes);
+}
+
+func (c *connBase) SetReadTimeout(nsec int64) os.Error {
+	c.fd.rdeadline_delta = nsec;
+	return nil;
+}
+
+func (c *connBase) SetWriteTimeout(nsec int64) os.Error {
+	c.fd.wdeadline_delta = nsec;
+	return nil;
+}
+
+func (c *connBase) SetTimeout(nsec int64) os.Error {
+	if e := c.SetReadTimeout(nsec); e != nil {
+		return e
+	}
+	return c.SetWriteTimeout(nsec)
+}
+
+func (c *connBase) SetReuseAddr(reuse bool) os.Error {
+	return setsockoptInt(c.sysFD(), syscall.SOL_SOCKET, syscall.SO_REUSEADDR, boolint(reuse));
+}
+
+func (c *connBase) BindToDevice(dev string) os.Error {
+	// TODO(rsc): call setsockopt with null-terminated string pointer
+	return os.EINVAL
+}
+
+func (c *connBase) SetDontRoute(dontroute bool) os.Error {
+	return setsockoptInt(c.sysFD(), syscall.SOL_SOCKET, syscall.SO_DONTROUTE, boolint(dontroute));
+}
+
+func (c *connBase) SetKeepAlive(keepalive bool) os.Error {
+	return setsockoptInt(c.sysFD(), syscall.SOL_SOCKET, syscall.SO_KEEPALIVE, boolint(keepalive));
+}
+
+func (c *connBase) SetLinger(sec int) os.Error {
+	var l syscall.Linger;
+	if sec >= 0 {
+		l.Onoff = 1;
+		l.Linger = int32(sec);
+	} else {
+		l.Onoff = 0;
+		l.Linger = 0;
+	}
+	e := syscall.SetsockoptLinger(c.sysFD(), syscall.SOL_SOCKET, syscall.SO_LINGER, &l);
+	return os.NewSyscallError("setsockopt", e);
+}
+
+
+type UnknownSocketError struct {
+	sa syscall.Sockaddr;
+}
+func (e *UnknownSocketError) String() string {
+	return "unknown socket address type " + reflect.Typeof(e.sa).String()
+}
+
+func sockaddrToString(sa syscall.Sockaddr) (name string, err os.Error) {
+	switch a := sa.(type) {
+	case *syscall.SockaddrInet4:
+		return joinHostPort(IP(&a.Addr).String(), itoa(a.Port)), nil;
+	case *syscall.SockaddrInet6:
+		return joinHostPort(IP(&a.Addr).String(), itoa(a.Port)), nil;
+	case *syscall.SockaddrUnix:
+		return a.Name, nil;
+	}
+
+	return "", &UnknownSocketError{sa};
+}
+

src/pkg/net/unixsock.go

+// 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.
+
+// Unix domain sockets
+
+package net
+
+import (
+	"os";
+	"syscall";
+)
+
+func unixSocket(net, laddr, raddr string, mode string) (fd *netFD, err os.Error) {
+	var proto int;
+	switch net {
+	default:
+		return nil, UnknownNetworkError(net);
+	case "unix":
+		proto = syscall.SOCK_STREAM;
+	case "unix-dgram":
+		proto = syscall.SOCK_DGRAM;
+	}
+
+	var la, ra syscall.Sockaddr;
+	switch mode {
+	default:
+		panic("unixSocket", mode);
+
+	case "dial":
+		if laddr != "" {
+			return nil, &OpError{mode, net, raddr, &AddrError{"unexpected local address", laddr}}
+		}
+		if raddr == "" {
+			return nil, &OpError{mode, net, "", errMissingAddress}
+		}
+		ra = &syscall.SockaddrUnix{Name: raddr};
+
+	case "listen":
+		if laddr == "" {
+			return nil, &OpError{mode, net, "", errMissingAddress}
+		}
+		la = &syscall.SockaddrUnix{Name: laddr};
+		if raddr != "" {
+			return nil, &OpError{mode, net, laddr, &AddrError{"unexpected remote address", raddr}}
+		}
+	}
+
+	fd, err = socket(net, laddr, raddr, syscall.AF_UNIX, 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};
+}
+
+// ConnUnix is an implementation of the Conn interface
+// for connections to Unix domain sockets.
+type ConnUnix struct {
+	connBase
+}
+
+func newConnUnix(fd *netFD, raddr string) *ConnUnix {
+	c := new(ConnUnix);
+	c.fd = fd;
+	c.raddr = raddr;
+	return c;
+}
+
+// DialUnix is like Dial but can only connect to Unix domain sockets
+// and returns a ConnUnix structure.  The laddr argument must be
+// the empty string; it is included only to match the signature of
+// the other dial routines.
+func DialUnix(net, laddr, raddr string) (c *ConnUnix, err os.Error) {
+	fd, e := unixSocket(net, laddr, raddr, "dial");
+	if e != nil {
+		return nil, e
+	}
+	return newConnUnix(fd, raddr), nil;
+}
+
+// ListenerUnix is a Unix domain socket listener.
+// Clients should typically use variables of type Listener
+// instead of assuming Unix domain sockets.
+type ListenerUnix struct {
+	fd *netFD;
+	laddr string
+}
+
+// ListenUnix announces on the Unix domain socket laddr and returns a Unix listener.
+// Net can be either "unix" (stream sockets) or "unix-dgram" (datagram sockets).
+func ListenUnix(net, laddr string) (l *ListenerUnix, err os.Error) {
+	fd, e := unixSocket(net, laddr, "", "listen");
+	if e != nil {
+		if pe, ok := e.(*os.PathError); ok {
+			e = pe.Error;
+		}
+		// Check for socket ``in use'' but ``refusing connections,''
+		// which means some program created it and exited
+		// without unlinking it from the file system.
+		// Clean up on that program's behalf and try again.
+		// Don't do this for Linux's ``abstract'' sockets, which begin with @.
+		if e != os.EADDRINUSE || laddr[0] == '@' {
+			return nil, e;
+		}
+		fd1, e1 := unixSocket(net, "", laddr, "dial");
+		if e1 == nil {
+			fd1.Close();
+		}
+		if pe, ok := e1.(*os.PathError); ok {
+			e1 = pe.Error;
+		}
+		if e1 != os.ECONNREFUSED {
+			return nil, e;
+		}
+		syscall.Unlink(laddr);
+		fd1, e1 = unixSocket(net, laddr, "", "listen");
+		if e1 != nil {
+			return nil, e;
+		}
+		fd = fd1;
+	}
+	e1 := syscall.Listen(fd.fd, 8); // listenBacklog());
+	if e1 != 0 {
+		syscall.Close(fd.fd);
+		return nil, &OpError{"listen", "unix", laddr, os.Errno(e1)};
+	}
+	return &ListenerUnix{fd, laddr}, nil;
+}
+
+// AcceptUnix accepts the next incoming call and returns the new connection
+// and the remote address.
+func (l *ListenerUnix) AcceptUnix() (c *ConnUnix, 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 newConnUnix(fd, fd.raddr), raddr, nil
+}
+
+// Accept implements the Accept method in the Listener interface;
+// it waits for the next call and returns a generic Conn.
+func (l *ListenerUnix) Accept() (c Conn, raddr string, err os.Error) {
+	// TODO(rsc): Should return l.AcceptUnix() be okay here?
+	// There is a type conversion -- the first return arg of
+	// l.AcceptUnix() is *ConnUnix and it gets converted to Conn
+	// in the explicit assignment.
+	c, raddr, err = l.AcceptUnix();
+	return;
+}
+
+
+// Close stops listening on the Unix address.
+// Already accepted connections are not closed.
+func (l *ListenerUnix) Close() os.Error {
+	if l == nil || l.fd == nil {
+		return os.EINVAL
+	}
+
+	// The operating system doesn't clean up
+	// the file that announcing created, so
+	// we have to clean it up ourselves.
+	// There's a race here--we can't know for
+	// sure whether someone else has come along
+	// and replaced our socket name already--
+	// but this sequence (remove then close)
+	// is at least compatible with the auto-remove
+	// sequence in ListenUnix.  It's only non-Go
+	// programs that can mess us up.
+	if l.laddr[0] != '@' {
+		syscall.Unlink(l.laddr);
+	}
+	err := l.fd.Close();
+	l.fd = nil;
+	return err;
+}
+
+// Addr returns the listener's network address.
+func (l *ListenerUnix) Addr() string {
+	return l.fd.addr();
+}