CODEWITHSUNDEEP
javahtmlwebsocket
Tyler
Tyler

Reputation: 11

HTML5 Websocket Server handshake (v.76) (Java)

I'm trying to build a Java-based HTML5 websocket server (v76) and have problems with the handshake. There are a few opensource Java solutions that supposedly support v76 but none of them seem to work.

I am certain my handshake response is correct (at least calculating the two key's responses). My question: Is Java by default Big Endian? Since the concatenation of the two key answers + the response bytes is the handshake answer, I'm having to do multiple type conversions (string to int, concat two ints into a string, then convert to byte and concat with the response bytes, then MD5 encoding), is there something in particular I need to be looking for? My response always seems accurate using Wireshark (# of bytes), but since the clients have no debug information it's hard to tell why my handshakes are failing.

Any supporting answers or working code would be EXTREMELY valuable to me.

Upvotes: 1

Views: 2729

Answers (3)

adotout
adotout

Reputation: 1190

Hey, this is a working example of the handshake producer for websockets version 76. If you use the example from the spec (http://tools.ietf.org/pdf/draft-hixie-thewebsocketprotocol-76.pdf) and print the output as a String, it produces the correct answer. 

    public byte[] getHandshake (String firstKey, String secondKey, byte[] last8)
    {
        byte[] toReturn = null;
        //Strip out numbers
        int firstNum = Integer.parseInt(firstKey.replaceAll("\\D", ""));
        int secondNum = Integer.parseInt(secondKey.replaceAll("\\D", ""));

        //Count spaces
        int firstDiv = firstKey.replaceAll("\\S", "").length();
        int secondDiv = secondKey.replaceAll("\\S", "").length();

        //Do the division
        int firstShake = firstNum / firstDiv;
        int secondShake = secondNum / secondDiv;

        //Prepare 128 bit byte array
        byte[] toMD5 = new byte[16];
        byte[] firstByte = ByteBuffer.allocate(4).putInt(firstShake).array();
        byte[] secondByte = ByteBuffer.allocate(4).putInt(secondShake).array();

        //Copy the bytes of the numbers you made into your md5 byte array
        System.arraycopy(firstByte, 0, toMD5, 0, 4);
        System.arraycopy(secondByte, 0, toMD5, 4, 4);
        System.arraycopy(last8, 0, toMD5, 8, 8);
        try
        {
            //MD5 everything together
            MessageDigest md5 = MessageDigest.getInstance("MD5");
            toReturn = md5.digest(toMD5);
        }
        catch (NoSuchAlgorithmException e)
        {
            e.printStackTrace();
        }

        return toReturn;
}

I wrote this so feel free to use it where ever.

EDIT: Some other problems I ran into - You MUST write the 'answer' to the handshake as bytes. If you try to write it back to the stream as a String it will fail (must be something to do with char conversion?). Also, make sure you're writing the rest of the response to the handshake exactly as it shows in the spec.

Upvotes: 1

TooTallNate
TooTallNate

Reputation: 1475

You can try my implementation: https://github.com/TooTallNate/Java-WebSocket

It supports draft 75 and 76 currently. Verified with current versions of Chrome and Safari. Good luck!

Upvotes: 0

Thorbjørn Ravn Andersen
Thorbjørn Ravn Andersen

Reputation: 75426

Jetty 7 supports web sockets, and is open source. You might find inspiration (but I would suggest you just embed Jetty in your application and be done with it).

http://blogs.webtide.com/gregw/entry/jetty_websocket_server

Upvotes: 0

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