Websocket hybi-17 new data format c++

Question

Websocket protocol has completely changed since version 8. Now the incoming messages from the browser are in a very different format and for me is really complicated.

  0                   1                   2                   3
  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 +-+-+-+-+-------+-+-------------+-------------------------------+
 |F|R|R|R| opcode|M| Payload len |    Extended payload length    |
 |I|S|S|S|  (4)  |A|     (7)     |             (16/64)           |
 |N|V|V|V|       |S|             |   (if payload len==126/127)   |
 | |1|2|3|       |K|             |                               |
 +-+-+-+-+-------+-+-------------+ - - - - - - - - - - - - - - - +
 |     Extended payload length continued, if payload len == 127  |
 + - - - - - - - - - - - - - - - +-------------------------------+
 |                               |Masking-key, if MASK set to 1  |
 +-------------------------------+-------------------------------+
 | Masking-key (continued)       |          Payload Data         |
 +-------------------------------- - - - - - - - - - - - - - - - +
 :                     Payload Data continued ...                :
 + - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - +
 |                     Payload Data continued ...                |
 +---------------------------------------------------------------+

Here is what I found from https://datatracker.ietf.org/doc/html/draft-ietf-hybi-thewebsocketprotocol-17

Does anybody know how to implement the server side read in c++ or c#? Or do you have a link to an example that is already working?

I know this server is correct but I need a code: http://websocket.org/echo.html

Answer 1

There's a great C++ WebSocket library here that supports hybi-17 (the latest revision), its header-only and uses just boost. It comes with example code and documentation: http://vinniefalco.github.io/

Here's a complete program that sends a message to the echo server:

#include <beast/websocket.hpp>
#include <beast/buffers_debug.hpp>
#include <boost/asio.hpp>
#include <iostream>
#include <string>

int main()
{
    // Normal boost::asio setup
    std::string const host = "echo.websocket.org";
    boost::asio::io_service ios;
    boost::asio::ip::tcp::resolver r(ios);
    boost::asio::ip::tcp::socket sock(ios);
    boost::asio::connect(sock,
        r.resolve(boost::asio::ip::tcp::resolver::query{host, "80"}));

    using namespace beast::websocket;

    // WebSocket connect and send message using beast
    stream<boost::asio::ip::tcp::socket&> ws(sock);
    ws.handshake(host, "/");
    ws.write(boost::asio::buffer("Hello, world!"));

    // Receive WebSocket message, print and close using beast
    beast::streambuf sb;
    opcode op;
    ws.read(op, sb);
    ws.close(close_code::normal);
    std::cout <<
        beast::debug::buffers_to_string(sb.data()) << "\n";
}

Answer 2

I've written a C++ server. See WsProtocol80::Read() for how to read hybi-17 messages. Note that the server uses custom string and socket classes so would be non-trivial to reuse but you should be able to easily follow what data is being read/written.

Feel free to ask any questions about specific parts of the code.

This wiki post may also be of interest.