CODEWITHSUNDEEP
c#websocketlistener
Tom Gullen
Tom Gullen

Reputation: 61775

Websocket server, client can't handshake

I'm testing using the latest version of Chrome (websocket version 13).

Here's my simple client page located at http://127.0.0.1/folder/default.aspx:

<script type="text/javascript">
    var socket = new WebSocket('ws://localhost:8181/websession');
    socket.onopen = function () {
        alert('handshake successfully established. May send data now...');
    };
    socket.onclose = function () {
        alert('connection closed');
    };
    socket.onmessage = function(msg) {
        alert(msg);
    };
</script>

And here's my listener (c#)

var listener = new TcpListener(IPAddress.Loopback, 8181);
listener.Start();
while (true)
{
    Console.WriteLine("Listening...");
    using (var client = listener.AcceptTcpClient())
    using (var stream = client.GetStream())
    using (var reader = new StreamReader(stream))
    using (var writer = new StreamWriter(stream))
    {
        writer.WriteLine("HTTP/1.1 101 Web Socket Protocol Handshake");
        writer.WriteLine("Upgrade: WebSocket");
        writer.WriteLine("Connection: Upgrade");
        writer.WriteLine("WebSocket-Origin: http://127.0.0.1");
        writer.WriteLine("WebSocket-Location: ws://localhost:8181/websession");
        writer.WriteLine("");
    }
    Console.WriteLine("Finished");
}

When I run the server, and then load the client page it only says "connection closed".

Could someone please tell me how to get this handshake performing correctly? As far as I can tell from documentation and previous questions, the response I'm sending back to the client looks correct.

Upvotes: 4

Views: 2447

Answers (3)

Andriy Vandych
Andriy Vandych

Reputation: 144

StreamReader and StreamWriter on dispose are closing underlying stream (NetworkStream).So client page only says "connection closed"

Upvotes: 1

L.B
L.B

Reputation: 116178

Based on your code ,this should work (at least with chrome)

var listener = new TcpListener(IPAddress.Loopback, 8181);
listener.Start();
while (true)
{
    Console.WriteLine("Listening...");
    using (var client = listener.AcceptTcpClient())
    using (var stream = client.GetStream())
    using (var reader = new StreamReader(stream))
    using (var writer = new StreamWriter(stream))
    {

        string line = null, key = "", responseKey = "";
        string MAGIC_STRING = "258EAFA5-E914-47DA-95CA-C5AB0DC85B11";
        while (line != "")
        {
            line = reader.ReadLine();
            if (line.StartsWith("Sec-WebSocket-Key:"))
            {
                key = line.Split(':')[1].Trim();
            }
        }

        if (key != "")
        {
            key += MAGIC_STRING;
            using (var sha1 = SHA1.Create())
            {
                responseKey = Convert.ToBase64String(sha1.ComputeHash(Encoding.ASCII.GetBytes(key)));
            }
        }

        // send handshake to the client
        writer.WriteLine("HTTP/1.1 101 Web Socket Protocol Handshake");
        writer.WriteLine("Upgrade: WebSocket");
        writer.WriteLine("Connection: Upgrade");
        writer.WriteLine("WebSocket-Origin: http://127.0.0.1");
        writer.WriteLine("WebSocket-Location: ws://localhost:8181/websession");
        if (!String.IsNullOrEmpty(responseKey)) 
            writer.WriteLine("Sec-WebSocket-Accept: " + responseKey);
        writer.WriteLine("");

        writer.Flush();

        SendString(stream, "This code works!!!!");
        SendString(stream, "This code also works!!!! ".PadRight(300, '.') + "\r\nEND");
    }
    Console.WriteLine("Finished");
}


void SendString(Stream s, string str)
{
    var buf = Encoding.UTF8.GetBytes(str);
    int frameSize = 64;

    var parts = buf.Select((b, i) => new { b, i })
                   .GroupBy(x => x.i / (frameSize - 1))
                   .Select(x => x.Select(y => y.b).ToArray())
                   .ToList();

    for (int i = 0; i < parts.Count; i++ )
    {
        byte cmd = 0;
        if (i == 0) cmd |= 1;
        if (i == parts.Count - 1) cmd |= 0x80;

        s.WriteByte(cmd);
        s.WriteByte((byte)parts[i].Length);
        s.Write(parts[i], 0, parts[i].Length);
    }

    s.Flush();
}

PS: Use

socket.onmessage = function(msg) {
    alert(msg.data);
};

to see the content of message sent by the server.

Upvotes: 3

Marc Gravell
Marc Gravell

Reputation: 1063884

You haven't computed the security hash. The client sends you a number, and there is another number hard-coded in the spec. You need to combine them as per the instructions in the spec, and return it as a header.

This demonstrates that your server is actually a web-socket server.

See RFC6455

Note that you might also want to consider whether to implement Hixie 76 in addition to the RFC.

Upvotes: 2

Related Questions