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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: 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_, 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;
- }
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