Fix for issue #4

Example/Program.cs

@@ -84,7 +84,10 @@ namespace Example
 
         ws.OnMessage += (sender, e) =>
         {
-          enNfMessage("[WebSocket] Message", e.Data, "notification-message-im");
+          if (!String.IsNullOrEmpty(e.Data))
+          {
+            enNfMessage("[WebSocket] Message", e.Data, "notification-message-im");
+          }
         };
 
         ws.OnError += (sender, e) =>
@@ -112,7 +115,8 @@ namespace Example
 
           Console.Write("> ");
           data = Console.ReadLine();
-          if (data == "exit" || !ws.IsConnected)
+          if (data == "exit")
+          //if (data == "exit" || !ws.IsConnected)
           {
             break;
           }

websocket-sharp.userprefs

@@ -1,5 +1,5 @@
 <Properties>
-  <MonoDevelop.Ide.Workspace ActiveConfiguration="Release_Ubuntu" />
+  <MonoDevelop.Ide.Workspace ActiveConfiguration="Debug" />
   <MonoDevelop.Ide.Workbench />
   <MonoDevelop.Ide.DebuggingService.Breakpoints>
     <BreakpointStore />

websocket-sharp/Frame/WsFrame.cs

@@ -111,9 +111,18 @@ namespace WebSocketSharp.Frame
     {
       Fin    = fin;
       Opcode = opcode;
-      Masked = mask;
 
       ulong dataLength = payloadData.Length;
+
+      if (dataLength == 0)
+      {
+        Masked = Mask.UNMASK;
+      }
+      else
+      {
+        Masked = mask;
+      }
+
       if (dataLength < 126)
       {
         PayloadLen = (byte)dataLength;
@@ -130,6 +139,7 @@ namespace WebSocketSharp.Frame
       }
 
       PayloadData = payloadData;
+
       if (Masked == Mask.MASK)
       {
         MaskingKey = new byte[4];
@@ -264,7 +274,11 @@ namespace WebSocketSharp.Frame
         }
       }
       // Payload Data
-      if (buffer3Len <= (ulong)_readBufferLen)
+      if (buffer3Len == 0)
+      {
+        buffer3 = new byte[]{};
+      }
+      else if (buffer3Len <= (ulong)_readBufferLen)
       {
         buffer3 = new byte[buffer3Len];
         readLen = stream.Read(buffer3, 0, (int)buffer3Len);

websocket-sharp/WebSocket.cs

@@ -74,6 +74,7 @@ namespace WebSocketSharp
     private string                          _protocol;
     private string                          _protocols;
     private volatile WsState                _readyState;
+    private AutoResetEvent                  _receivedPong;
     private SslStream                       _sslStream;
     private TcpClient                       _tcpClient;
     private Uri                             _uri;
@@ -116,25 +117,8 @@ namespace WebSocketSharp
     {
       get
       {
-        if (_tcpClient == null) return false;
-
-        var socket = _tcpClient.Client;
-        if (!socket.Connected) return false;
-
-        if (socket.Poll(0, SelectMode.SelectWrite) &&
-            !socket.Poll(0, SelectMode.SelectError))
-        {
-//          var buffer = new byte[1];
-//
-//          if (socket.Receive(buffer, SocketFlags.Peek) != 0)
-//          {
-//            return true;
-//          }
-
-          return true;
-        }
-
-        return false;
+        if (_readyState != WsState.OPEN) return false;
+        return Ping();
       }
     }
 
@@ -198,6 +182,7 @@ namespace WebSocketSharp
       _fragmentLen         = 1024; // Max value is int.MaxValue - 14.
       _protocol            = String.Empty;
       _readyState          = WsState.CONNECTING;
+      _receivedPong        = new AutoResetEvent(false);
       _unTransmittedBuffer = new SynchronizedCollection<WsFrame>();
     }
 
@@ -894,6 +879,7 @@ namespace WebSocketSharp
             }
             else if (frame.Opcode == Opcode.PONG)
             {// FINAL & PONG
+              _receivedPong.Set();
               OnMessage.Emit(this, new MessageEventArgs(frame.Opcode, frame.PayloadData));
             }
             else
@@ -913,7 +899,9 @@ namespace WebSocketSharp
           {
             case Opcode.TEXT:
             case Opcode.BINARY:
+              goto default;            
             case Opcode.PONG:
+              _receivedPong.Set();
               goto default;
             case Opcode.CLOSE:
               #if DEBUG
@@ -1194,12 +1182,12 @@ namespace WebSocketSharp
       Close(CloseStatusCode.AWAY);
     }
 
-    public void Ping()
+    public bool Ping()
     {
-      Ping(String.Empty);
+      return Ping(String.Empty);
     }
 
-    public void Ping(string data)
+    public bool Ping(string data)
     {
       var payloadData = new PayloadData(data);
 
@@ -1207,11 +1195,13 @@ namespace WebSocketSharp
       {
         var msg = "Ping frame must have a payload length of 125 bytes or less.";
         error(msg);
-        return;
+        return false;
       }
 
       var frame = createFrame(Fin.FINAL, Opcode.PING, payloadData);
-      send(frame);
+      if (!send(frame)) return false;
+
+      return _receivedPong.WaitOne(5 * 1000);
     }
 
     public void Send(string data)