Make Socket::connect try all addresses given.

runtime/bin/socket_patch.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.
 
 patch class RawServerSocket {
   /* patch */ static Future<RawServerSocket> bind(address,
                                                   int port,
                                                   {int backlog: 0,
                                                    bool v6Only: false}) {
     return _RawServerSocket.bind(address, port, backlog, v6Only);
@@ skipping 463 matching lines @@
                   return map;
                 });
             return map.values.toList();
           }
         });
   }
 
   static Future<_NativeSocket> connect(host, int port) {
     return new Future.value(host)
         .then((host) {
-          if (host is _InternetAddress) return host;
+          if (host is _InternetAddress) return [host];
           return lookup(host)
               .then((list) {
                 if (list.length == 0) {
                   throw createError(response, "Failed host lookup: '$host'");
                 }
-                return list[0];
+                return list;
               });
         })
-        .then((address) {
-          var socket = new _NativeSocket.normal();
-          socket.address = address;
-          var result = socket.nativeCreateConnect(
-              address._in_addr, port);
-          if (result is OSError) {
-            throw createError(result, "Connection failed", address, port);
-          } else {
-            socket.port;  // Query the local port, for error messages.
-            var completer = new Completer();
-            // Setup handlers for receiving the first write event which
-            // indicate that the socket is fully connected.
-            socket.setHandlers(
-                write: () {
-                  socket.setListening(read: false, write: false);
-                  completer.complete(socket);
-                },
-                error: (e) {
-                  socket.close();
-                  completer.completeError(e);
-                }
-            );
-            socket.setListening(read: false, write: true);
-            return completer.future;
+        .then((addresses) {
+          assert(addresses is List);
+          var completer = new Completer();
+          var it = addresses.iterator;
+          void run(error) {
+            if (!it.moveNext()) {
+              assert(error != null);
+              completer.completeError(error);
+              return;
+            }
+            var address = it.current;
+            var socket = new _NativeSocket.normal();
+            socket.address = address;
+            var result = socket.nativeCreateConnect(address._in_addr, port);
+            if (result is OSError) {
+              run(error != null ? error :
+                  createError(result, "Connection failed", address, port));
+            } else {
+              socket.port;  // Query the local port, for error messages.
+              // Setup handlers for receiving the first write event which
+              // indicate that the socket is fully connected.
+              socket.setHandlers(
+                  write: () {
+                    socket.setListening(read: false, write: false);
+                    completer.complete(socket);
+                  },
+                  error: (e) {
+                    socket.close();

[Søren Gjesse, 2014/05/01 07:23:34]

Add a comment that this keeps the first error.

[Anders Johnsen, 2014/05/01 08:42:38]

Done.

+                    run(error != null ? error : e);

[codefu, 2014/05/01 18:52:02]

If addresses.length > 1 and the first address connects... if later in time the
socket has an error won't this try to reconnect on later addresses (and possibly
throw an error since completer is already done)?

suggested: bool retry = true; before run(), then retry = false just before
comleter.complete(socket).  in error if(retry) run(...);

[Anders Johnsen, 2014/05/01 19:27:58]

No, this error handler is only called when connecting fails. As soon as the
connection is made, we disable listening (see above) and later register another
error handler.

+                  }
+              );
+              socket.setListening(read: false, write: true);
+            }
           }
+          run(null);
+          return completer.future;
         });
   }
 
   static Future<_NativeSocket> bind(host,
                                     int port,
                                     int backlog,
                                     bool v6Only) {
     return new Future.value(host)
         .then((host) {
           if (host is _InternetAddress) return host;
@@ skipping 1252 matching lines @@
                        String address,
                        List<int> in_addr,
                        int port) {
   return new Datagram(
       data,
       new _InternetAddress(address, null, in_addr),
       port);
 }
 
 String _socketsStats() => _SocketsObservatory.toJSON();