No onMessage events when connected to jWebSocket Android client about fleck

[statianzo]

Could you set the FleckLog.LogLevel to debug and attach the output here?
On May 20, 2012 10:35 PM, "arct" <
[email protected]>
wrote:

When testing the jWebSocket Android client "fundamental" demo apk, the
client can connect with Fleck, but closes the connection upon sending a
message. No onMessage event is fired at the Fleck server.

---

Reply to this email directly or view it on GitHub:
#41

[arct]

5/21/2012 6:46:20 PM [Info] Server started at ws://localhost:8080 (Fleck server started)
5/21/2012 6:46:23 PM [Debug] Client Connected (jWebsocket Android client opens connection)
5/21/2012 6:46:23 PM [Debug] 236 bytes read
5/21/2012 6:46:23 PM [Debug] Building Hybi-14 Response
5/21/2012 6:46:23 PM [Debug] Sent 129 bytes (Fleck server waits for message)
5/21/2012 6:46:28 PM [Debug] 69 bytes read (jWebSocket Android client sends message)
5/21/2012 6:46:28 PM [Debug] Error while reading Fleck.WebSocketException: Exception of type 'Fleck.WebSocketException' was thrown.
at Fleck.Handlers.Hybi13Handler.ReceiveData(List1 data, ReadState readState, Action2 processFrame)
at Fleck.Handlers.Hybi13Handler.<>c__DisplayClassa.b__5(List1 d) at Fleck.Handlers.ComposableHandler.Receive(IEnumerable1 data)
at Fleck.WebSocketConnection.<>c__DisplayClassb.b__a(Int32 r)
at Fleck.SocketWrapper.<>c__DisplayClassb.b__9(Task1 t) at System.Threading.Tasks.Task1.<>c__DisplayClass17.b__16(Object obj)
at System.Threading.Tasks.Task.InnerInvoke()
at System.Threading.Tasks.Task.Execute()
5/21/2012 6:46:28 PM [Debug] Sent 4 bytes (jWebsocket Android client closes connection)

[statianzo]

The source of the exception is this line. It's designed to ensure that an incoming frame is valid. If an invalid frame is received, an exception is thrown and the connection is closed.

if (!isMasked
    || !Enum.IsDefined(typeof(FrameType), frameType)
    || reservedBits != 0 //Must be zero per spec 5.2
    || (frameType == FrameType.Continuation && !readState.FrameType.HasValue))
    throw new WebSocketException(WebSocketStatusCodes.ProtocolError);

It's not passing one of the checks. It's possible that jWebsocket isn't matching spec. I would say that dropping a breakpoint on this conditional and finding the failing expression would be your best bet as to determining the cause of the error. Would you mind doing that?

[arct]

I added watches for each operand in that expression and set a breakpoint there. After stepping through to the exception, they evaluated as follows:

!isMasked : TRUE
!Enum.IsDefined(typeof(FrameType), frameType) : FALSE
reservedBits != 0 : FALSE
(frameType == FrameType.Continuation && !readState.FrameType.HasValue) : FALSE
WebSocketStatusCodes.ProtocolError = 1002

It appears jWebSocket Android client does not mask frames when sending. That's probably the culprit, because I don't think that's compliant behavior per RFC 6455. Am I correct?

[statianzo]

That's correct. RFC 6455 states both of the following:

If the data is being sent by the client, the frame(s) MUST be masked as defined in Section 5.3.

The server MUST close the connection upon receiving a frame that is not masked.

If you're interested in helping jWebSocket, the masking algorithm is quite simple, and a C# implementation exists here.

public static byte[] TransformBytes(byte[] bytes, int mask)
{
    var output = new byte[bytes.Length];
    var maskBytes = BitConverter.GetBytes(mask);
    if (BitConverter.IsLittleEndian)
        Array.Reverse(maskBytes);

    for (int i = 0; i < bytes.Length; i++)
    {
        output[i] = (byte)(bytes[i] ^ maskBytes[i % 4]);
    }

    return output;
}

[arct]

Thank you for your help.

[WirawanBagus]

Has this problem been solved? Because I see the same problem now. .

[statianzo]

the issue seemed to be with jwebsocket. best to check there.