Add a new attachTo method to HttpServer, for using an existing ServerSocket.

runtime/bin/http_impl.dart

 // Copyright (c) 2012, 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.
 
 class _HttpRequestResponseBase {
   _HttpRequestResponseBase(_HttpConnectionBase this._httpConnection)
       : _contentLength = -1,
         _keepAlive = false,
         _headers = new Map();
 
@@ skipping 611 matching lines @@
   HttpResponse _response;
 
   // Callbacks.
   var requestReceived;
 }
 
 
 // HTTP server waiting for socket connections. The connections are
 // managed by the server and as requests are received the request.
 class _HttpServer implements HttpServer {
+  _HttpServer() : _connections = new Set<_HttpConnection>();
+
   void listen(String host, int port, [int backlog = 5]) {
+    listenOn(new ServerSocket(host, port, backlog));
+    _closeServer = true;
+  }
 
+  void listenOn(ServerSocket serverSocket) {
     void onConnection(Socket socket) {
       // Accept the client connection.
       _HttpConnection connection = new _HttpConnection(this);
-      connection._connectionEstablished(socket);
       connection.requestReceived = _onRequest;
-      _connections.add(connection);
       connection.onDisconnect = () => _connections.remove(connection);
       connection.onError = (e) {
         if (_onError != null) _onError(e);
       };
+      connection._connectionEstablished(socket);
+      _connections.add(connection);
     }
-
-    _connections = new Set<_HttpConnection>();
-    _server = new ServerSocket(host, port, backlog);
-    _server.onConnection = onConnection;
+    serverSocket.onConnection = onConnection;
+    _server = serverSocket;
+    _closeServer = false;
   }
 
   void close() {
-    _server.close();
+    if (_server !== null && _closeServer) {
+      _server.close();
+    }
+    _server = null;
     for (_HttpConnection connection in _connections) {
       connection._socket.close();
     }
+    _connections.clear();
   }
 
-  int get port() => _server.port;
+  int get port() => _server === null ? -1 : _server.port;

[Søren Gjesse, 2012/04/02 08:16:45]

How about throwing an exception if the server has no socket?

[Anders Johnsen, 2012/04/02 08:24:35]

Even better! :)

 
   void set onError(void callback(Exception e)) {
     _onError = callback;
   }
 
   void set onRequest(void callback(HttpRequest, HttpResponse)) {
     _onRequest = callback;
   }
 
   ServerSocket _server;  // The server listen socket.
+  bool _closeServer = false;
   Set<_HttpConnection> _connections;  // Set of currently connected clients.
   Function _onRequest;
   Function _onError;
 }
 
 
 class _HttpClientRequest
     extends _HttpRequestResponseBase implements HttpClientRequest {
   static final int START = 0;
   static final int HEADERS_SENT = 1;
@@ skipping 515 matching lines @@
     sockets.addFirst(socketConn);
     socketConn._markReturned();
   }
 
   Function _onOpen;
   Map<String, Queue<_SocketConnection>> _openSockets;
   Set<_SocketConnection> _activeSockets;
   Timer _evictionTimer;
   bool _shutdown;  // Has this HTTP client been shutdown?
 }