DO NOT SUBMIT: Unix domain sockets. From CL 1061283003.

sdk/lib/io/socket.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of dart.io;
 
 
 /**
  * [InternetAddressType] is the type an [InternetAddress]. Currently,
  * IP version 4 (IPv4) and IP version 6 (IPv6) are supported.
@@ skipping 126 matching lines @@
    * addresses. If [type] is either [InternetAddressType.IP_V4] or
    * [InternetAddressType.IP_V6] it will only lookup addresses of the
    * specified type. The order of the list can, and most likely will,
    * change over time.
    */
   external static Future<List<InternetAddress>> lookup(
       String host, {InternetAddressType type: InternetAddressType.ANY});
 }
 
 
+class UnixDomainAddress {
+  final String path;
+  bool get isLoopback => false;  // HACK.
+  UnixDomainAddress(this.path);
+}
+
+
 /**
  * A [NetworkInterface] represent an active network interface on the current
  * system. It contains a list of [InternetAddress]s, that's bound to the
  * interface.
  */
 abstract class NetworkInterface {
   /**
    * Get the name of the [NetworkInterface].
    */
   String get name;
@@ skipping 595 matching lines @@
    * If an error occur when trying to join the multicase group an
    * exception is thrown.
    */
   void leaveMulticast(InternetAddress group, {NetworkInterface interface});
 }
 
 
 class SocketException implements IOException {
   final String message;
   final OSError osError;
-  final InternetAddress address;
+  final /* InternetAddress or UnixDomainAddress */ address;
   final int port;
 
   const SocketException(this.message, {this.osError, this.address, this.port});
   const SocketException.closed()
       : message = 'Socket has been closed',
         osError = null,
         address = null,
         port = null;
 
   String toString() {
     StringBuffer sb = new StringBuffer();
     sb.write("SocketException");
     if (!message.isEmpty) {
       sb.write(": $message");
       if (osError != null) {
         sb.write(" ($osError)");
       }
     } else if (osError != null) {
       sb.write(": $osError");
     }
     if (address != null) {
       sb.write(", address = ${address.host}");
     }
     if (port != null) {
       sb.write(", port = $port");
     }
     return sb.toString();
   }
 }