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- //
- // 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 client, asynchronous
- //
- //------------------------------------------------------------------------------
- #include <boost/beast/core.hpp>
- #include <boost/beast/http.hpp>
- #include <boost/beast/version.hpp>
- #include <boost/asio/strand.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>
- 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::tcp_stream stream_;
- beast::flat_buffer buffer_; // (Must persist between reads)
- http::request<http::empty_body> req_;
- http::response<http::string_body> res_;
- public:
- // Objects are constructed with a strand to
- // ensure that handlers do not execute concurrently.
- explicit
- session(net::io_context& ioc)
- : resolver_(net::make_strand(ioc))
- , stream_(net::make_strand(ioc))
- {
- }
- // Start the asynchronous operation
- void
- run(
- char const* host,
- char const* port,
- char const* target,
- int version)
- {
- // 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
- stream_.expires_after(std::chrono::seconds(30));
- // Make the connection on the IP address we get from a lookup
- 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");
- // Set a timeout on the operation
- 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;
- // Gracefully close the socket
- stream_.socket().shutdown(tcp::socket::shutdown_both, ec);
- // not_connected happens sometimes so don't bother reporting it.
- if(ec && ec != beast::errc::not_connected)
- 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 <host> <port> <target> [<HTTP version: 1.0 or 1.1(default)>]\n" <<
- "Example:\n" <<
- " http-client-async www.example.com 80 /\n" <<
- " http-client-async www.example.com 80 / 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;
- // Launch the asynchronous operation
- std::make_shared<session>(ioc)->run(host, port, target, version);
- // Run the I/O service. The call will return when
- // the get operation is complete.
- ioc.run();
- return EXIT_SUCCESS;
- }
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