string ~ ubyte

[Bob Cowdery]

On 31/10/2010 13:13, div0 wrote:
> On 31/10/2010 11:36, Bob Cowdery wrote:
>> Hi
>> I'm implementing a web sockets server as part of the UI for my
>> application. It's almost working but the connection closes on me just
>> after the handshake. I'm pretty sure the handshake response I'm sending
>> is incorrect.
>>
>> This is the last bit of the code (I've missed ot the bit that creates
>> the parts as I think that is ok):
>>
>>          // Create the challenge response
>>          // The response is formed by a concatenation of
>>          // part_1 + part_2 + key (where parts are 32 bit integers and
>> key is 8 bytes)
>>          // The parts must be in big endian order and the whole forms a
>> 128 bit value
>>          // The response is then the MD5 hash of this value
>>          writeln("Creating response");
>>          auto response = new ubyte[16];
>>          response[0] = part_1&  0xFF;
>>          response[1] = (part_1>>  8)&  0xFF;
>>          response[2] = (part_1>>  16)&  0xFF;
>>          response[3] = (part_1>>  24)&  0xFF;
>>          response[4] = part_2&  0xFF;
>>          response[5] = (part_2>>  8)&  0xFF;
>>          response[6] = (part_2>>  16)&  0xFF;
>>          response[7] = (part_2>>  24)&  0xFF;
>>          foreach(i, value; key) {
>>              response[i+8] = value;
>>          }
>>
>>          // Create an MD5 hash of the result.
>>          ubyte digest[16];
>>          sum(digest, response);
>>
>>          // Send the handshake
>>          writeln("Handshake sending: ", handshake ~
>> digestToString(digest));
>>          this.sock.send(handshake ~ digestToString(digest));
>>
>> The result of running gives me a handshake respose of:
>>
>>          Creating response
>>          Handshake sending: HTTP/1.1 101 Web Socket Protocol Handshake
>>          Upgrade: WebSocket
>>          Connection: Upgrade
>>          WebSocket-Origin: http://localhost:9000
>>          WebSocket-Location: ws://localhost:9999/
>>          Sec-Websocket-Origin: http://localhost:9000
>>          Sec-Websocket-Location: ws://localhost:9999/
>>
>>          5C368EF0F874025639911E2BC5F01412
>>
>> This all looks good except the string at the end (the digest) which has
>> 32 characters whereas I think the client is expecting 16. I'm guessing
>> the string is created as UTF16. Is there a way to get this to be 16
>> characters?
>>
>> bob
>
> If the client is expecting 16 bytes, then it wants the response in
> binary. You're converting it to hex text which is why you've got twice
> as many characters as you are expecting. just remove the
> digestToString bit and send the raw ubyte array.
>
> You may or may not need to reverse the md5 as well.
> Not sure if Endianess applies to a md5.
>
Thanks. If I do :
this.sock.send(cast(ubyte[])handshake ~ digest);
it looks better but stil closes the connection. I guess I will have to
look at the protocol spec again and see if I can figure what I'm doing
wrong.

bob