libs/beast/example/http/client/awaitable-ssl/http_client_awaitable_ssl.cpp
// // Copyright (c) 2022 Klemens D. Morgenstern (klemens dot morgenstern at gmx dot net) // // 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 client, coroutine // //------------------------------------------------------------------------------ #include <boost/beast/core.hpp> #include <boost/beast/http.hpp> #include <boost/beast/ssl.hpp> #include <boost/beast/version.hpp> #include <boost/asio/as_tuple.hpp> #include <boost/asio/awaitable.hpp> #include <boost/asio/co_spawn.hpp> #include <boost/asio/detached.hpp> #include <boost/asio/use_awaitable.hpp> #if defined(BOOST_ASIO_HAS_CO_AWAIT) #include <cstdlib> #include <functional> #include <iostream> #include <string> #include "example/common/root_certificates.hpp" 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> //------------------------------------------------------------------------------ // Performs an HTTP GET and prints the response net::awaitable<void> do_session( std::string host, std::string port, std::string target, int version, ssl::context& ctx) { // These objects perform our I/O // They use an executor with a default completion token of use_awaitable // This makes our code easy, but will use exceptions as the default error handling, // i.e. if the connection drops, we might see an exception. // See async_shutdown for error handling with an error_code. auto resolver = net::use_awaitable.as_default_on(tcp::resolver(co_await net::this_coro::executor)); using executor_with_default = net::use_awaitable_t<>::executor_with_default<net::any_io_executor>; using tcp_stream = typename beast::tcp_stream::rebind_executor<executor_with_default>::other; // We construct the ssl stream from the already rebound tcp_stream. beast::ssl_stream<tcp_stream> stream{ net::use_awaitable.as_default_on(beast::tcp_stream(co_await net::this_coro::executor)), ctx}; // Set SNI Hostname (many hosts need this to handshake successfully) if(! SSL_set_tlsext_host_name(stream.native_handle(), host.c_str())) throw boost::system::system_error(static_cast<int>(::ERR_get_error()), net::error::get_ssl_category()); // Look up the domain name auto const results = co_await resolver.async_resolve(host, port); // Set the timeout. beast::get_lowest_layer(stream).expires_after(std::chrono::seconds(30)); // Make the connection on the IP address we get from a lookup co_await beast::get_lowest_layer(stream).async_connect(results); // Set the timeout. beast::get_lowest_layer(stream).expires_after(std::chrono::seconds(30)); // Perform the SSL handshake co_await stream.async_handshake(ssl::stream_base::client); // Set up an HTTP GET request message http::request<http::string_body> req{http::verb::get, target, version}; req.set(http::field::host, host); req.set(http::field::user_agent, BOOST_BEAST_VERSION_STRING); // Set the timeout. beast::get_lowest_layer(stream).expires_after(std::chrono::seconds(30)); // Send the HTTP request to the remote host co_await http::async_write(stream, req); // This buffer is used for reading and must be persisted beast::flat_buffer b; // Declare a container to hold the response http::response<http::dynamic_body> res; // Receive the HTTP response co_await http::async_read(stream, b, res); // Write the message to standard out std::cout << res << std::endl; // Set the timeout. beast::get_lowest_layer(stream).expires_after(std::chrono::seconds(30)); // Gracefully close the stream - do not threat every error as an exception! auto [ec] = co_await stream.async_shutdown(net::as_tuple(net::use_awaitable)); if (ec == net::error::eof) { // Rationale: // http://stackoverflow.com/questions/25587403/boost-asio-ssl-async-shutdown-always-finishes-with-an-error ec = {}; } if (ec) throw boost::system::system_error(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-awaitable <host> <port> <target> [<HTTP version: 1.0 or 1.1(default)>]\n" << "Example:\n" << " http-client-awaitable www.example.com 443 /\n" << " http-client-awaitable 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 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}; // 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 net::co_spawn( ioc, do_session(host, port, target, version, ctx), // If the awaitable exists with an exception, it gets delivered here as `e`. // This can happen for regular errors, such as connection drops. [](std::exception_ptr e) { if (!e) return ; try { std::rethrow_exception(e); } catch(std::exception & ex) { std::cerr << "Error: " << ex.what() << "\n"; } }); // Run the I/O service. The call will return when // the get operation is complete. ioc.run(); return EXIT_SUCCESS; } #else int main(int, char * []) { std::printf("awaitables require C++20\n"); return 1; } #endif