Function main

example/websocket/client/sync-ssl/websocket_client_sync_ssl.cpp:36–129

Sends a WebSocket message and prints the response

// 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-ssl <host> <port> <text>\n" <<
                "Example:\n" <<
                "    websocket-client-sync-ssl echo.websocket.org 443 \"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;

        // The SSL context is required, and holds certificates
        ssl::context ctx{ssl::context::tlsv12_client};

        // Verify the remote server's certificate
        ctx.set_verify_mode(ssl::verify_peer);

        // This holds the root certificate used for verification
        load_root_certificates(ctx);

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

        // 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(beast::get_lowest_layer(ws), results);

        // Set SNI Hostname (many hosts need this to handshake successfully)
        if(! SSL_set_tlsext_host_name(ws.next_layer().native_handle(), host.c_str()))
        {
            throw beast::system_error(
                static_cast<int>(::ERR_get_error()),
                net::error::get_ssl_category());
        }

        // Set the expected hostname in the peer certificate for verification
        ws.next_layer().set_verify_callback(ssl::host_name_verification(host));

        // 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());

        // Perform the SSL handshake
        ws.next_layer().handshake(ssl::stream_base::client);