add timeout on ws connection

Author: rinick

lib/src/http/client_link.dart

@@ -227,10 +227,14 @@ class HttpClientLink extends ClientLink {
         wsUrl = '$wsUrl$tokenHash';
       }
 
-      var socket = await HttpHelper.connectToWebSocket(
-        wsUrl,
-        useStandardWebSocket: useStandardWebSocket
-      );
+      var socket = await awaitWithTimeout(
+          HttpHelper.connectToWebSocket(wsUrl,
+              useStandardWebSocket: useStandardWebSocket),
+          // websocket initialization should take no more than 60 seconds
+          60000,
+          (WebSocket socket){socket.close();},
+          (err){}
+          );
 
       _wsConnection = new WebSocketConnection(
           socket,

lib/src/utils/promise_timeout.dart

@@ -0,0 +1,29 @@
+part of dslink.utils;
+
+Future<T> awaitWithTimeout<T>(Future<T> future, int timeoutMs,
+    Function onSuccessAfterTimeout, Function onErrorAfterTimeout) {
+  Completer<T> completer = new Completer();
+
+  Timer timer = new Timer(new Duration(milliseconds: timeoutMs), () {
+    if (!completer.isCompleted) {
+      completer.completeError(new Exception('Future timeout before complete'));
+    }
+  });
+  future.then((T t) {
+    if (completer.isCompleted) {
+      onSuccessAfterTimeout(t);
+    } else {
+      timer.cancel();
+      completer.complete(t);
+    }
+  }).catchError((err) {
+    if (completer.isCompleted) {
+      onErrorAfterTimeout(err);
+    } else {
+      timer.cancel();
+      completer.completeError(err);
+    }
+  });
+
+  return completer.future;
+}

lib/utils.dart

@@ -17,6 +17,7 @@ part "src/utils/codec.dart";
 part "src/utils/dslink_json.dart";
 part "src/utils/list.dart";
 part "src/utils/uri_component.dart";
+part "src/utils/promise_timeout.dart";
 
 typedef ExecutableFunction();
 typedef T Producer<T>();