libs/beast/example/http/client/async-ssl-system-executor/http_client_async_ssl_system_executor.cpp
// // 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: HTTP SSL client, asynchronous, using system_executor // //------------------------------------------------------------------------------ #include "example/common/root_certificates.hpp" #include <boost/beast/core.hpp> #include <boost/beast/http.hpp> #include <boost/beast/ssl.hpp> #include <boost/beast/version.hpp> #include <boost/asio/strand.hpp> #include <boost/asio/system_executor.hpp> #include <cstdlib> #include <functional> #include <iostream> #include <memory> #include <string> namespace beast = boost::beast; // from <boost/beast.hpp> namespace http = beast::http; // from <boost/beast/http.hpp> namespace net = boost::asio; // from <boost/asio.hpp> namespace ssl = boost::asio::ssl; // from <boost/asio/ssl.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"; } // Performs an HTTP GET and prints the response class session : public std::enable_shared_from_this<session> { tcp::resolver resolver_; beast::ssl_stream<beast::tcp_stream> stream_; beast::flat_buffer buffer_; // (Must persist between reads) http::request<http::empty_body> req_; http::response<http::string_body> res_; // Objects are constructed with a strand to // ensure that handlers do not execute concurrently. session(net::strand<net::system_executor> strand, ssl::context& ctx) : resolver_(strand) , stream_(strand, ctx) { } public: // Delegate construction to a prive constructor to be able to use // the same strand for both I/O object. explicit session(ssl::context& ctx) : session(net::make_strand(net::system_executor()), ctx) { } // Start the asynchronous operation void run( char const* host, char const* port, char const* target, int version) { // Set SNI Hostname (many hosts need this to handshake successfully) if(! SSL_set_tlsext_host_name(stream_.native_handle(), host)) { beast::error_code ec{static_cast<int>(::ERR_get_error()), net::error::get_ssl_category()}; std::cerr << ec.message() << "\n"; return; } // Set up an HTTP GET request message req_.version(version); req_.method(http::verb::get); req_.target(target); req_.set(http::field::host, host); req_.set(http::field::user_agent, BOOST_BEAST_VERSION_STRING); // Look up the domain name resolver_.async_resolve( host, port, beast::bind_front_handler( &session::on_resolve, shared_from_this())); } void on_resolve( beast::error_code ec, tcp::resolver::results_type results) { if(ec) return fail(ec, "resolve"); // Set a timeout on the operation beast::get_lowest_layer(stream_).expires_after(std::chrono::seconds(30)); // Make the connection on the IP address we get from a lookup beast::get_lowest_layer(stream_).async_connect( results, beast::bind_front_handler( &session::on_connect, shared_from_this())); } void on_connect(beast::error_code ec, tcp::resolver::results_type::endpoint_type) { if(ec) return fail(ec, "connect"); // Perform the SSL handshake stream_.async_handshake( ssl::stream_base::client, beast::bind_front_handler( &session::on_handshake, shared_from_this())); } void on_handshake(beast::error_code ec) { if(ec) return fail(ec, "handshake"); // Set a timeout on the operation beast::get_lowest_layer(stream_).expires_after(std::chrono::seconds(30)); // Send the HTTP request to the remote host http::async_write(stream_, req_, 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"); // Receive the HTTP response http::async_read(stream_, buffer_, res_, 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); if(ec) return fail(ec, "read"); // Write the message to standard out std::cout << res_ << std::endl; // Set a timeout on the operation beast::get_lowest_layer(stream_).expires_after(std::chrono::seconds(30)); // Gracefully close the stream stream_.async_shutdown( beast::bind_front_handler( &session::on_shutdown, shared_from_this())); } void on_shutdown(beast::error_code ec) { if(ec == net::error::eof) { // Rationale: // http://stackoverflow.com/questions/25587403/boost-asio-ssl-async-shutdown-always-finishes-with-an-error ec = {}; } if(ec) return fail(ec, "shutdown"); // If we get here then the connection is closed gracefully } }; //------------------------------------------------------------------------------ int main(int argc, char** argv) { // Check command line arguments. if(argc != 4 && argc != 5) { std::cerr << "Usage: http-client-async-ssl-system-executor <host> <port> <target> [<HTTP version: 1.0 or 1.1(default)>]\n" << "Example:\n" << " http-client-async-ssl-system-executor www.example.com 443 /\n" << " http-client-async-ssl-system-executor www.example.com 443 / 1.0\n"; return EXIT_FAILURE; } auto const host = argv[1]; auto const port = argv[2]; auto const target = argv[3]; int version = argc == 5 && !std::strcmp("1.0", argv[4]) ? 10 : 11; // The SSL context is required, and holds certificates ssl::context ctx{ssl::context::tlsv12_client}; // This holds the root certificate used for verification load_root_certificates(ctx); // Verify the remote server's certificate ctx.set_verify_mode(ssl::verify_peer); // Launch the asynchronous operation std::make_shared<session>(ctx)->run(host, port, target, version); // The async operations will run on the system_executor. // Because the main thread has nothing to do in this example, we just wait // for the system_executor to run out of work. net::query(net::system_executor(), net::execution::context).join(); return EXIT_SUCCESS; }