SslClientSession.h

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regarding copyright ownership.  The ASF licenses this file
to you under the Apache License, Version 2.0 (the
"License"; you may not use this file except in compliance
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  http://www.apache.org/licenses/LICENSE-2.0
 
Unless required by applicable law or agreed to in writing,
software distributed under the License is distributed on an
"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
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specific language governing permissions and limitations
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#pragma once
 
#include "../AbstractClientSessionCRTP.h"
 
#include <boost/version.hpp>
#if BOOST_VERSION < 106800
#include "ssl_stream.h"
#elif BOOST_VERSION < 107000
#include <boost/beast/experimental/core/ssl_stream.hpp>
#else
#include <boost/beast/http.hpp>
#include <boost/beast/ssl.hpp>
#include <boost/beast/websocket/ssl.hpp>
#endif
 
namespace http = boost::beast::http;    // from <boost/beast/http.hpp>
 
namespace ETP_NS
{
    class SslClientSession : public AbstractClientSessionCRTP<SslClientSession>
    {
    private:
        websocket::stream<boost::beast::ssl_stream<tcp::socket>> ws_;
        http::request<http::empty_body> proxyHandshake;
        http::response<http::empty_body> proxyHandshakeResponse;
        // use own response parser
        // NOTE: 200 response to a CONNECT request from a tunneling proxy do not carry a body
        http::response_parser<http::empty_body> http_proxy_handshake_parser;
 
    public:
        /*
        * @param frameSize              Sets the size of the write buffer used by the implementation to send frames : https://www.boost.org/doc/libs/1_75_0/libs/beast/doc/html/beast/ref/boost__beast__websocket__stream/write_buffer_bytes/overload1.html.
        */
        FETPAPI_DLL_IMPORT_OR_EXPORT SslClientSession(boost::asio::ssl::context& ctx,
            InitializationParameters const* initializationParams, const std::string& target, const std::string& authorization, const std::string& proxyAuthorization = "",
            const std::map<std::string, std::string>& additionalHandshakeHeaderFields = {}, std::size_t frameSize = 4096);
 
        virtual ~SslClientSession() {}
 
        // Called by the base class
        FETPAPI_DLL_IMPORT_OR_EXPORT websocket::stream<boost::beast::ssl_stream<tcp::socket>>& ws() { return ws_; }
 
        bool isTls() const final { return true; }
 
        void on_resolve(boost::system::error_code ec, tcp::resolver::results_type results)
        {
            if (ec) {
                std::cerr << "on_resolve : " << ec.message() << std::endl;
            }
 
            // Make the connection on the IP address we get from a lookup
            boost::asio::async_connect(
                ws_.next_layer().next_layer(),
                results.begin(),
                results.end(),
                std::bind(
                    &SslClientSession::on_ssl_connect,
                    std::static_pointer_cast<SslClientSession>(shared_from_this()),
                    std::placeholders::_1));
        }
 
        void on_ssl_connect(boost::system::error_code ec) {
            if (ec) {
                std::cerr << "on_ssl_connect : " << ec.message() << std::endl;
            }
 
            if (!proxyHost.empty()) {
                proxyHandshake.version(11);
                proxyHandshake.method(http::verb::connect);
                proxyHandshake.target(etpServerHost + ':' + etpServerPort);
                proxyHandshake.set(http::field::host, etpServerHost + ':' + etpServerPort);
                if (!etpServerAuthorization.empty()) {
                    proxyHandshake.set(http::field::authorization, etpServerAuthorization);
                }
                if (!proxyAuthorization.empty()) {
                    proxyHandshake.set(http::field::proxy_authorization, proxyAuthorization);
                }
 
                // Send the handshake to the proxy
                http::async_write(ws_.next_layer().next_layer(), proxyHandshake,
                    std::bind(
                        &SslClientSession::on_proxy_handshake_write,
                        std::static_pointer_cast<SslClientSession>(shared_from_this()),
                        std::placeholders::_1,
                        std::placeholders::_2));
            }
            else {
                // Perform the SSL handshake
                ws_.next_layer().async_handshake(
                    boost::asio::ssl::stream_base::client,
                    std::bind(
                        &AbstractClientSessionCRTP::on_connect,
                        std::static_pointer_cast<AbstractClientSessionCRTP>(shared_from_this()),
                        std::placeholders::_1));
            }
        }
 
        void
            on_proxy_handshake_write(
                boost::system::error_code ec,
                std::size_t bytes_transferred)
        {
            boost::ignore_unused(bytes_transferred);
 
            if (ec) {
                std::cerr << "Proxy handshake write : " << ec.message() << std::endl;
                return;
            }
 
            http_proxy_handshake_parser.skip(true); // see https://stackoverflow.com/a/49837467/10904212
 
            // Receive the HTTP response
            http::async_read(ws_.next_layer().next_layer(), receivedBuffer, http_proxy_handshake_parser,
                std::bind(
                    &SslClientSession::on_proxy_handshake_read,
                    std::static_pointer_cast<SslClientSession>(shared_from_this()),
                    std::placeholders::_1,
                    std::placeholders::_2));
        }
 
        void
            on_proxy_handshake_read(
                boost::system::error_code ec,
                std::size_t bytes_transferred)
        {
            boost::ignore_unused(bytes_transferred);
            if (ec) {
                std::cerr << "read : " << ec.message() << std::endl;
                return;
            }
 
            // Perform the SSL handshake
            ws_.next_layer().async_handshake(
                boost::asio::ssl::stream_base::client,
                std::bind(
                    &AbstractClientSessionCRTP::on_connect,
                    std::static_pointer_cast<AbstractClientSessionCRTP>(shared_from_this()),
                    std::placeholders::_1));
        }
    };
}