C++ websocket

stackoverflow C or C++ websocket client working example

https://www.boost.org/doc/libs/develop/libs/beast/example/websocket/client/sync-ssl/websocket_client_sync_ssl.cpp

https://www.boost.org/doc/libs/master/libs/beast/example/websocket/server/async/websocket_server_async.cpp

https://www.boost.org/doc/libs/master/libs/beast/doc/html/beast/examples.html

用到的库为：#include "boost/beast/websocket.hpp"

参考wenet里用的是boost的库，这里也用boost学习C++的websocket。

Simple WebSocket Client

https://www.boost.org/doc/libs/master/libs/beast/doc/html/beast/quick_start/websocket_client.html

一个websocket 客户端 C++版本的例子，用boost实现

#include <boost/beast/core.hpp>
#include <boost/beast/websocket.hpp>
#include <boost/asio/connect.hpp>
#include <boost/asio/ip/tcp.hpp>
#include <cstdlib>
#include <iostream>
#include <string>

namespace beast = boost::beast;         // from <boost/beast.hpp>
namespace http = beast::http;           // from <boost/beast/http.hpp>
namespace websocket = beast::websocket; // from <boost/beast/websocket.hpp>
namespace net = boost::asio;            // from <boost/asio.hpp>
using tcp = boost::asio::ip::tcp;       // from <boost/asio/ip/tcp.hpp>

// Sends a WebSocket message and prints the response
int main(int argc, char** argv)
{
    try
    {
        // Check command line arguments.
        if(argc != 4)
        {
            std::cerr <<
                "Usage: websocket-client-sync <host> <port> <text>\n" <<
                "Example:\n" <<
                "    websocket-client-sync echo.websocket.org 80 \"Hello, world!\"\n";
            return EXIT_FAILURE;
        }
        std::string host = argv[1];
        auto const  port = argv[2];
        auto const  text = argv[3];

        // The io_context is required for all I/O
        net::io_context ioc;

        // These objects perform our I/O
        tcp::resolver resolver{ioc};
        websocket::stream<tcp::socket> ws{ioc};

        // Look up the domain name
        auto const results = resolver.resolve(host, port);

        // Make the connection on the IP address we get from a lookup
        auto ep = net::connect(ws.next_layer(), results);

        // Update the host_ string. This will provide the value of the
        // Host HTTP header during the WebSocket handshake.
        // See https://tools.ietf.org/html/rfc7230#section-5.4
        host += ':' + std::to_string(ep.port());

        // Set a decorator to change the User-Agent of the handshake
        ws.set_option(websocket::stream_base::decorator(
            [](websocket::request_type& req)
            {
                req.set(http::field::user_agent,
                    std::string(BOOST_BEAST_VERSION_STRING) +
                        " websocket-client-coro");
            }));

        // Perform the websocket handshake
        ws.handshake(host, "/");

        // Send the message
        ws.write(net::buffer(std::string(text)));

        // This buffer will hold the incoming message
        beast::flat_buffer buffer;

        // Read a message into our buffer
        ws.read(buffer);

        // Close the WebSocket connection
        ws.close(websocket::close_code::normal);

        // If we get here then the connection is closed gracefully

        // The make_printable() function helps print a ConstBufferSequence
        std::cout << beast::make_printable(buffer.data()) << std::endl;
    }
    catch(std::exception const& e)
    {
        std::cerr << "Error: " << e.what() << std::endl;
        return EXIT_FAILURE;
    }
    return EXIT_SUCCESS;
}

websocket server

服务器端

//
// Copyright (c) 2016-2019 Vinnie Falco (vinnie dot falco at gmail dot com)
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//
// Official repository: https://github.com/boostorg/beast
//

//------------------------------------------------------------------------------
//
// Example: WebSocket server, asynchronous
//
//------------------------------------------------------------------------------

    #include <boost/beast/core.hpp>
#include <boost/beast/websocket.hpp>
#include <boost/asio/dispatch.hpp>
#include <boost/asio/strand.hpp>
#include <algorithm>
#include <cstdlib>
#include <functional>
#include <iostream>
#include <memory>
#include <string>
#include <thread>
#include <vector>

namespace beast = boost::beast;         // from <boost/beast.hpp>
namespace http = beast::http;           // from <boost/beast/http.hpp>
namespace websocket = beast::websocket; // from <boost/beast/websocket.hpp>
namespace net = boost::asio;            // from <boost/asio.hpp>
using tcp = boost::asio::ip::tcp;       // from <boost/asio/ip/tcp.hpp>

//------------------------------------------------------------------------------

// Report a failure
void
fail(beast::error_code ec, char const* what)
{
    std::cerr << what << ": " << ec.message() << "\n";
}

// Echoes back all received WebSocket messages
class session : public std::enable_shared_from_this<session>
{
    websocket::stream<beast::tcp_stream> ws_;
    beast::flat_buffer buffer_;

public:
    // Take ownership of the socket
    explicit
    session(tcp::socket&& socket)
        : ws_(std::move(socket))
    {
    }

    // Get on the correct executor
    void
    run()
    {
        // We need to be executing within a strand to perform async operations
        // on the I/O objects in this session. Although not strictly necessary
        // for single-threaded contexts, this example code is written to be
        // thread-safe by default.
        net::dispatch(ws_.get_executor(),
            beast::bind_front_handler(
                &session::on_run,
                shared_from_this()));
    }

    // Start the asynchronous operation
    void
    on_run()
    {
        // Set suggested timeout settings for the websocket
        ws_.set_option(
            websocket::stream_base::timeout::suggested(
                beast::role_type::server));

        // Set a decorator to change the Server of the handshake
        ws_.set_option(websocket::stream_base::decorator(
            [](websocket::response_type& res)
            {
                res.set(http::field::server,
                    std::string(BOOST_BEAST_VERSION_STRING) +
                        " websocket-server-async");
            }));
        // Accept the websocket handshake
        ws_.async_accept(
            beast::bind_front_handler(
                &session::on_accept,
                shared_from_this()));
    }

    void
    on_accept(beast::error_code ec)
    {
        if(ec)
            return fail(ec, "accept");

        // Read a message
        do_read();
    }

    void
    do_read()
    {
        // Read a message into our buffer
        ws_.async_read(
            buffer_,
            beast::bind_front_handler(
                &session::on_read,
                shared_from_this()));
    }

    void
    on_read(
        beast::error_code ec,
        std::size_t bytes_transferred)
    {
        boost::ignore_unused(bytes_transferred);

        // This indicates that the session was closed
        if(ec == websocket::error::closed)
            return;

        if(ec)
            return fail(ec, "read");

        // Echo the message
        ws_.text(ws_.got_text());
        ws_.async_write(
            buffer_.data(),
            beast::bind_front_handler(
                &session::on_write,
                shared_from_this()));
    }

    void
    on_write(
        beast::error_code ec,
        std::size_t bytes_transferred)
    {
        boost::ignore_unused(bytes_transferred);

        if(ec)
            return fail(ec, "write");

        // Clear the buffer
        buffer_.consume(buffer_.size());

        // Do another read
        do_read();
    }
};

//------------------------------------------------------------------------------

// Accepts incoming connections and launches the sessions
class listener : public std::enable_shared_from_this<listener>
{
    net::io_context& ioc_;
    tcp::acceptor acceptor_;

public:
    listener(
        net::io_context& ioc,
        tcp::endpoint endpoint)
        : ioc_(ioc)
        , acceptor_(ioc)
    {
        beast::error_code ec;

        // Open the acceptor
        acceptor_.open(endpoint.protocol(), ec);
        if(ec)
        {
            fail(ec, "open");
            return;
        }

        // Allow address reuse
        acceptor_.set_option(net::socket_base::reuse_address(true), ec);
        if(ec)
        {
            fail(ec, "set_option");
            return;
        }

        // Bind to the server address
        acceptor_.bind(endpoint, ec);
        if(ec)
        {
            fail(ec, "bind");
            return;
        }

        // Start listening for connections
        acceptor_.listen(
            net::socket_base::max_listen_connections, ec);
        if(ec)
        {
            fail(ec, "listen");
            return;
        }
    }

    // Start accepting incoming connections
    void
    run()
    {
        do_accept();
    }

private:
    void
    do_accept()
    {
        // The new connection gets its own strand
        acceptor_.async_accept(
            net::make_strand(ioc_),
            beast::bind_front_handler(
                &listener::on_accept,
                shared_from_this()));
    }

    void
    on_accept(beast::error_code ec, tcp::socket socket)
    {
        if(ec)
        {
            fail(ec, "accept");
        }
        else
        {
            // Create the session and run it
            std::make_shared<session>(std::move(socket))->run();
        }

        // Accept another connection
        do_accept();
    }
};

//------------------------------------------------------------------------------

int main(int argc, char* argv[])
{
    // Check command line arguments.
    if (argc != 4)
    {
        std::cerr <<
            "Usage: websocket-server-async <address> <port> <threads>\n" <<
            "Example:\n" <<
            "    websocket-server-async 0.0.0.0 8080 1\n";
        return EXIT_FAILURE;
    }
    auto const address = net::ip::make_address(argv[1]);
    auto const port = static_cast<unsigned short>(std::atoi(argv[2]));
    auto const threads = std::max<int>(1, std::atoi(argv[3]));

    // The io_context is required for all I/O
    net::io_context ioc{threads};

    // Create and launch a listening port
    std::make_shared<listener>(ioc, tcp::endpoint{address, port})->run();

    // Run the I/O service on the requested number of threads
    std::vector<std::thread> v;
    v.reserve(threads - 1);
    for(auto i = threads - 1; i > 0; --i)
        v.emplace_back(
        [&ioc]
        {
            ioc.run();
        });
    ioc.run();

    return EXIT_SUCCESS;
}