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146 lines
4.3 KiB
C++
146 lines
4.3 KiB
C++
//
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// Copyright (c) 2022 Klemens D. Morgenstern (klemens dot morgenstern at gmx dot net)
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//
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// Distributed under the Boost Software License, Version 1.0. (See accompanying
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// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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//
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// Official repository: https://github.com/boostorg/beast
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//
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//------------------------------------------------------------------------------
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//
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// Example: HTTP client, coroutine
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//
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//------------------------------------------------------------------------------
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#include <boost/asio/awaitable.hpp>
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#include <boost/asio/co_spawn.hpp>
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#include <boost/asio/io_context.hpp>
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#include <boost/beast/core.hpp>
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#include <boost/beast/http.hpp>
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#include <boost/beast/version.hpp>
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#include <cstdlib>
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#include <iostream>
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#include <string>
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#if defined(BOOST_ASIO_HAS_CO_AWAIT)
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namespace beast = boost::beast;
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namespace http = beast::http;
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namespace net = boost::asio;
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// Performs an HTTP GET and prints the response
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net::awaitable<void>
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do_session(std::string host, std::string port, std::string target, int version)
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{
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auto executor = co_await net::this_coro::executor;
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auto resolver = net::ip::tcp::resolver{ executor };
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auto stream = beast::tcp_stream{ executor };
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// Look up the domain name
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auto const results = co_await resolver.async_resolve(host, port);
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// Set the timeout.
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stream.expires_after(std::chrono::seconds(30));
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// Make the connection on the IP address we get from a lookup
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co_await stream.async_connect(results);
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// Set up an HTTP GET request message
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http::request<http::string_body> req{ http::verb::get, target, version };
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req.set(http::field::host, host);
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req.set(http::field::user_agent, BOOST_BEAST_VERSION_STRING);
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// Set the timeout.
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stream.expires_after(std::chrono::seconds(30));
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// Send the HTTP request to the remote host
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co_await http::async_write(stream, req);
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// This buffer is used for reading and must be persisted
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beast::flat_buffer buffer;
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// Declare a container to hold the response
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http::response<http::dynamic_body> res;
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// Receive the HTTP response
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co_await http::async_read(stream, buffer, res);
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// Write the message to standard out
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std::cout << res << std::endl;
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// Gracefully close the socket
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beast::error_code ec;
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stream.socket().shutdown(net::ip::tcp::socket::shutdown_both, ec);
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// not_connected happens sometimes
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// so don't bother reporting it.
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//
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if(ec && ec != beast::errc::not_connected)
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throw boost::system::system_error(ec, "shutdown");
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// If we get here then the connection is closed gracefully
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}
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//------------------------------------------------------------------------------
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int
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main(int argc, char** argv)
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{
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try
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{
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// Check command line arguments.
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if(argc != 4 && argc != 5)
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{
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std::cerr << "Usage: http-client-awaitable <host> <port> <target> [<HTTP version: 1.0 or 1.1(default)>]\n"
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<< "Example:\n"
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<< " http-client-awaitable www.example.com 80 /\n"
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<< " http-client-awaitable www.example.com 80 / 1.0\n";
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return EXIT_FAILURE;
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}
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auto const host = argv[1];
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auto const port = argv[2];
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auto const target = argv[3];
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auto const version =
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argc == 5 && !std::strcmp("1.0", argv[4]) ? 10 : 11;
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// The io_context is required for all I/O
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net::io_context ioc;
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// Launch the asynchronous operation
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net::co_spawn(
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ioc,
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do_session(host, port, target, version),
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// If the awaitable exists with an exception, it gets delivered here
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// as `e`. This can happen for regular errors, such as connection
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// drops.
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[](std::exception_ptr e)
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{
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if(e)
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std::rethrow_exception(e);
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});
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// Run the I/O service. The call will return when
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// the get operation is complete.
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ioc.run();
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}
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catch(std::exception const& e)
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{
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std::cerr << "Error: " << e.what() << std::endl;
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return EXIT_FAILURE;
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}
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return EXIT_SUCCESS;
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}
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#else
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int
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main(int, char*[])
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{
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std::printf("awaitables require C++20\n");
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return EXIT_FAILURE;
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}
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#endif
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