libs/beast/example/advanced/server/advanced_server.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: Advanced server // //------------------------------------------------------------------------------ #include <boost/beast/core.hpp> #include <boost/beast/http.hpp> #include <boost/beast/websocket.hpp> #include <boost/beast/version.hpp> #include <boost/asio/bind_executor.hpp> #include <boost/asio/signal_set.hpp> #include <boost/asio/strand.hpp> #include <boost/make_unique.hpp> #include <boost/optional.hpp> #include <algorithm> #include <cstdlib> #include <functional> #include <iostream> #include <memory> #include <string> #include <thread> #include <vector> namespace beast = boost::beast; // from <boost/beast.hpp> namespace http = beast::http; // from <boost/beast/http.hpp> namespace websocket = beast::websocket; // from <boost/beast/websocket.hpp> namespace net = boost::asio; // from <boost/asio.hpp> using tcp = boost::asio::ip::tcp; // from <boost/asio/ip/tcp.hpp> // Return a reasonable mime type based on the extension of a file. beast::string_view mime_type(beast::string_view path) { using beast::iequals; auto const ext = [&path] { auto const pos = path.rfind("."); if(pos == beast::string_view::npos) return beast::string_view{}; return path.substr(pos); }(); if(iequals(ext, ".htm")) return "text/html"; if(iequals(ext, ".html")) return "text/html"; if(iequals(ext, ".php")) return "text/html"; if(iequals(ext, ".css")) return "text/css"; if(iequals(ext, ".txt")) return "text/plain"; if(iequals(ext, ".js")) return "application/javascript"; if(iequals(ext, ".json")) return "application/json"; if(iequals(ext, ".xml")) return "application/xml"; if(iequals(ext, ".swf")) return "application/x-shockwave-flash"; if(iequals(ext, ".flv")) return "video/x-flv"; if(iequals(ext, ".png")) return "image/png"; if(iequals(ext, ".jpe")) return "image/jpeg"; if(iequals(ext, ".jpeg")) return "image/jpeg"; if(iequals(ext, ".jpg")) return "image/jpeg"; if(iequals(ext, ".gif")) return "image/gif"; if(iequals(ext, ".bmp")) return "image/bmp"; if(iequals(ext, ".ico")) return "image/vnd.microsoft.icon"; if(iequals(ext, ".tiff")) return "image/tiff"; if(iequals(ext, ".tif")) return "image/tiff"; if(iequals(ext, ".svg")) return "image/svg+xml"; if(iequals(ext, ".svgz")) return "image/svg+xml"; return "application/text"; } // Append an HTTP rel-path to a local filesystem path. // The returned path is normalized for the platform. std::string path_cat( beast::string_view base, beast::string_view path) { if(base.empty()) return std::string(path); std::string result(base); #ifdef BOOST_MSVC char constexpr path_separator = '\\'; if(result.back() == path_separator) result.resize(result.size() - 1); result.append(path.data(), path.size()); for(auto& c : result) if(c == '/') c = path_separator; #else char constexpr path_separator = '/'; if(result.back() == path_separator) result.resize(result.size() - 1); result.append(path.data(), path.size()); #endif return result; } // This function produces an HTTP response for the given // request. The type of the response object depends on the // contents of the request, so the interface requires the // caller to pass a generic lambda for receiving the response. template< class Body, class Allocator, class Send> void handle_request( beast::string_view doc_root, http::request<Body, http::basic_fields<Allocator>>&& req, Send&& send) { // Returns a bad request response auto const bad_request = [&req](beast::string_view why) { http::response<http::string_body> res{http::status::bad_request, req.version()}; res.set(http::field::server, BOOST_BEAST_VERSION_STRING); res.set(http::field::content_type, "text/html"); res.keep_alive(req.keep_alive()); res.body() = std::string(why); res.prepare_payload(); return res; }; // Returns a not found response auto const not_found = [&req](beast::string_view target) { http::response<http::string_body> res{http::status::not_found, req.version()}; res.set(http::field::server, BOOST_BEAST_VERSION_STRING); res.set(http::field::content_type, "text/html"); res.keep_alive(req.keep_alive()); res.body() = "The resource '" + std::string(target) + "' was not found."; res.prepare_payload(); return res; }; // Returns a server error response auto const server_error = [&req](beast::string_view what) { http::response<http::string_body> res{http::status::internal_server_error, req.version()}; res.set(http::field::server, BOOST_BEAST_VERSION_STRING); res.set(http::field::content_type, "text/html"); res.keep_alive(req.keep_alive()); res.body() = "An error occurred: '" + std::string(what) + "'"; res.prepare_payload(); return res; }; // Make sure we can handle the method if( req.method() != http::verb::get && req.method() != http::verb::head) return send(bad_request("Unknown HTTP-method")); // Request path must be absolute and not contain "..". if( req.target().empty() || req.target()[0] != '/' || req.target().find("..") != beast::string_view::npos) return send(bad_request("Illegal request-target")); // Build the path to the requested file std::string path = path_cat(doc_root, req.target()); if(req.target().back() == '/') path.append("index.html"); // Attempt to open the file beast::error_code ec; http::file_body::value_type body; body.open(path.c_str(), beast::file_mode::scan, ec); // Handle the case where the file doesn't exist if(ec == beast::errc::no_such_file_or_directory) return send(not_found(req.target())); // Handle an unknown error if(ec) return send(server_error(ec.message())); // Cache the size since we need it after the move auto const size = body.size(); // Respond to HEAD request if(req.method() == http::verb::head) { http::response<http::empty_body> res{http::status::ok, req.version()}; res.set(http::field::server, BOOST_BEAST_VERSION_STRING); res.set(http::field::content_type, mime_type(path)); res.content_length(size); res.keep_alive(req.keep_alive()); return send(std::move(res)); } // Respond to GET request http::response<http::file_body> res{ std::piecewise_construct, std::make_tuple(std::move(body)), std::make_tuple(http::status::ok, req.version())}; res.set(http::field::server, BOOST_BEAST_VERSION_STRING); res.set(http::field::content_type, mime_type(path)); res.content_length(size); res.keep_alive(req.keep_alive()); return send(std::move(res)); } //------------------------------------------------------------------------------ // Report a failure void fail(beast::error_code ec, char const* what) { std::cerr << what << ": " << ec.message() << "\n"; } // Echoes back all received WebSocket messages class websocket_session : public std::enable_shared_from_this<websocket_session> { websocket::stream<beast::tcp_stream> ws_; beast::flat_buffer buffer_; public: // Take ownership of the socket explicit websocket_session(tcp::socket&& socket) : ws_(std::move(socket)) { } // Start the asynchronous accept operation template<class Body, class Allocator> void do_accept(http::request<Body, http::basic_fields<Allocator>> req) { // Set suggested timeout settings for the websocket ws_.set_option( websocket::stream_base::timeout::suggested( beast::role_type::server)); // Set a decorator to change the Server of the handshake ws_.set_option(websocket::stream_base::decorator( [](websocket::response_type& res) { res.set(http::field::server, std::string(BOOST_BEAST_VERSION_STRING) + " advanced-server"); })); // Accept the websocket handshake ws_.async_accept( req, beast::bind_front_handler( &websocket_session::on_accept, shared_from_this())); } private: void on_accept(beast::error_code ec) { if(ec) return fail(ec, "accept"); // Read a message do_read(); } void do_read() { // Read a message into our buffer ws_.async_read( buffer_, beast::bind_front_handler( &websocket_session::on_read, shared_from_this())); } void on_read( beast::error_code ec, std::size_t bytes_transferred) { boost::ignore_unused(bytes_transferred); // This indicates that the websocket_session was closed if(ec == websocket::error::closed) return; if(ec) fail(ec, "read"); // Echo the message ws_.text(ws_.got_text()); ws_.async_write( buffer_.data(), beast::bind_front_handler( &websocket_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"); // Clear the buffer buffer_.consume(buffer_.size()); // Do another read do_read(); } }; //------------------------------------------------------------------------------ // Handles an HTTP server connection class http_session : public std::enable_shared_from_this<http_session> { // This queue is used for HTTP pipelining. class queue { enum { // Maximum number of responses we will queue limit = 8 }; // The type-erased, saved work item struct work { virtual ~work() = default; virtual void operator()() = 0; }; http_session& self_; std::vector<std::unique_ptr<work>> items_; public: explicit queue(http_session& self) : self_(self) { static_assert(limit > 0, "queue limit must be positive"); items_.reserve(limit); } // Returns `true` if we have reached the queue limit bool is_full() const { return items_.size() >= limit; } // Called when a message finishes sending // Returns `true` if the caller should initiate a read bool on_write() { BOOST_ASSERT(! items_.empty()); auto const was_full = is_full(); items_.erase(items_.begin()); if(! items_.empty()) (*items_.front())(); return was_full; } // Called by the HTTP handler to send a response. template<bool isRequest, class Body, class Fields> void operator()(http::message<isRequest, Body, Fields>&& msg) { // This holds a work item struct work_impl : work { http_session& self_; http::message<isRequest, Body, Fields> msg_; work_impl( http_session& self, http::message<isRequest, Body, Fields>&& msg) : self_(self) , msg_(std::move(msg)) { } void operator()() { http::async_write( self_.stream_, msg_, beast::bind_front_handler( &http_session::on_write, self_.shared_from_this(), msg_.need_eof())); } }; // Allocate and store the work items_.push_back( boost::make_unique<work_impl>(self_, std::move(msg))); // If there was no previous work, start this one if(items_.size() == 1) (*items_.front())(); } }; beast::tcp_stream stream_; beast::flat_buffer buffer_; std::shared_ptr<std::string const> doc_root_; queue queue_; // The parser is stored in an optional container so we can // construct it from scratch it at the beginning of each new message. boost::optional<http::request_parser<http::string_body>> parser_; public: // Take ownership of the socket http_session( tcp::socket&& socket, std::shared_ptr<std::string const> const& doc_root) : stream_(std::move(socket)) , doc_root_(doc_root) , queue_(*this) { } // Start the session void run() { do_read(); } private: void do_read() { // Construct a new parser for each message parser_.emplace(); // Apply a reasonable limit to the allowed size // of the body in bytes to prevent abuse. parser_->body_limit(10000); // Set the timeout. stream_.expires_after(std::chrono::seconds(30)); // Read a request using the parser-oriented interface http::async_read( stream_, buffer_, *parser_, beast::bind_front_handler( &http_session::on_read, shared_from_this())); } void on_read(beast::error_code ec, std::size_t bytes_transferred) { boost::ignore_unused(bytes_transferred); // This means they closed the connection if(ec == http::error::end_of_stream) return do_close(); if(ec) return fail(ec, "read"); // See if it is a WebSocket Upgrade if(websocket::is_upgrade(parser_->get())) { // Create a websocket session, transferring ownership // of both the socket and the HTTP request. std::make_shared<websocket_session>( stream_.release_socket())->do_accept(parser_->release()); return; } // Send the response handle_request(*doc_root_, std::move(parser_->release()), queue_); // If we aren't at the queue limit, try to pipeline another request if(! queue_.is_full()) do_read(); } void on_write(bool close, beast::error_code ec, std::size_t bytes_transferred) { boost::ignore_unused(bytes_transferred); if(ec) return fail(ec, "write"); if(close) { // This means we should close the connection, usually because // the response indicated the "Connection: close" semantic. return do_close(); } // Inform the queue that a write completed if(queue_.on_write()) { // Read another request do_read(); } } void do_close() { // Send a TCP shutdown beast::error_code ec; stream_.socket().shutdown(tcp::socket::shutdown_send, ec); // At this point the connection is closed gracefully } }; //------------------------------------------------------------------------------ // Accepts incoming connections and launches the sessions class listener : public std::enable_shared_from_this<listener> { net::io_context& ioc_; tcp::acceptor acceptor_; std::shared_ptr<std::string const> doc_root_; public: listener( net::io_context& ioc, tcp::endpoint endpoint, std::shared_ptr<std::string const> const& doc_root) : ioc_(ioc) , acceptor_(net::make_strand(ioc)) , doc_root_(doc_root) { beast::error_code ec; // Open the acceptor acceptor_.open(endpoint.protocol(), ec); if(ec) { fail(ec, "open"); return; } // Allow address reuse acceptor_.set_option(net::socket_base::reuse_address(true), ec); if(ec) { fail(ec, "set_option"); return; } // Bind to the server address acceptor_.bind(endpoint, ec); if(ec) { fail(ec, "bind"); return; } // Start listening for connections acceptor_.listen( net::socket_base::max_listen_connections, ec); if(ec) { fail(ec, "listen"); return; } } // Start accepting incoming connections void run() { do_accept(); } private: void do_accept() { // The new connection gets its own strand acceptor_.async_accept( net::make_strand(ioc_), beast::bind_front_handler( &listener::on_accept, shared_from_this())); } void on_accept(beast::error_code ec, tcp::socket socket) { if(ec) { fail(ec, "accept"); } else { // Create the http session and run it std::make_shared<http_session>( std::move(socket), doc_root_)->run(); } // Accept another connection do_accept(); } }; //------------------------------------------------------------------------------ int main(int argc, char* argv[]) { // Check command line arguments. if (argc != 5) { std::cerr << "Usage: advanced-server <address> <port> <doc_root> <threads>\n" << "Example:\n" << " advanced-server 0.0.0.0 8080 . 1\n"; return EXIT_FAILURE; } auto const address = net::ip::make_address(argv[1]); auto const port = static_cast<unsigned short>(std::atoi(argv[2])); auto const doc_root = std::make_shared<std::string>(argv[3]); auto const threads = std::max<int>(1, std::atoi(argv[4])); // The io_context is required for all I/O net::io_context ioc{threads}; // Create and launch a listening port std::make_shared<listener>( ioc, tcp::endpoint{address, port}, doc_root)->run(); // Capture SIGINT and SIGTERM to perform a clean shutdown net::signal_set signals(ioc, SIGINT, SIGTERM); signals.async_wait( [&](beast::error_code const&, int) { // Stop the `io_context`. This will cause `run()` // to return immediately, eventually destroying the // `io_context` and all of the sockets in it. ioc.stop(); }); // Run the I/O service on the requested number of threads std::vector<std::thread> v; v.reserve(threads - 1); for(auto i = threads - 1; i > 0; --i) v.emplace_back( [&ioc] { ioc.run(); }); ioc.run(); // (If we get here, it means we got a SIGINT or SIGTERM) // Block until all the threads exit for(auto& t : v) t.join(); return EXIT_SUCCESS; }