libs/beast/example/advanced/server-flex-awaitable/advanced_server_flex_awaitable.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: Advanced server, flex (plain + SSL)
//
//------------------------------------------------------------------------------
#include "example/common/server_certificate.hpp"
#include <boost/beast/core.hpp>
#include <boost/beast/http.hpp>
#include <boost/beast/ssl.hpp>
#include <boost/beast/websocket.hpp>
#include <boost/beast/version.hpp>
#include <boost/asio/as_tuple.hpp>
#include <boost/asio/awaitable.hpp>
#include <boost/asio/bind_executor.hpp>
#include <boost/asio/bind_cancellation_slot.hpp>
#include <boost/asio/co_spawn.hpp>
#include <boost/asio/deferred.hpp>
#include <boost/asio/detached.hpp>
#include <boost/asio/dispatch.hpp>
#include <boost/asio/experimental/parallel_group.hpp>
#include <boost/asio/signal_set.hpp>
#include <boost/asio/strand.hpp>
#include <boost/make_unique.hpp>
#include <boost/asio/use_awaitable.hpp>
#include <boost/optional.hpp>
#include <algorithm>
#include <cstdlib>
#include <functional>
#include <iostream>
#include <memory>
#include <string>
#include <thread>
#include <vector>
#if defined(BOOST_ASIO_HAS_CO_AWAIT)
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>
namespace ssl = boost::asio::ssl; // from <boost/asio/ssl.hpp>
using tcp = boost::asio::ip::tcp; // from <boost/asio/ip/tcp.hpp>
using executor_type = net::io_context::executor_type;
using executor_with_default = net::as_tuple_t<net::use_awaitable_t<executor_type>>::executor_with_default<executor_type>;
// 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;
}
// Return a response for the given request.
//
// The concrete type of the response message (which depends on the
// request), is type-erased in message_generator.
template<class Body, class Allocator>
http::message_generator
handle_request(
beast::string_view doc_root,
http::request<Body, http::basic_fields<Allocator>>&& req)
{
// 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 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 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 not_found(req.target());
// Handle an unknown error
if(ec)
return 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 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 res;
}
//------------------------------------------------------------------------------
// Report a failure
void
fail(beast::error_code ec, char const* what)
{
// ssl::error::stream_truncated, also known as an SSL "short read",
// indicates the peer closed the connection without performing the
// required closing handshake (for example, Google does this to
// improve performance). Generally this can be a security issue,
// but if your communication protocol is self-terminated (as
// it is with both HTTP and WebSocket) then you may simply
// ignore the lack of close_notify.
//
// https://github.com/boostorg/beast/issues/38
//
// https://security.stackexchange.com/questions/91435/how-to-handle-a-malicious-ssl-tls-shutdown
//
// When a short read would cut off the end of an HTTP message,
// Beast returns the error beast::http::error::partial_message.
// Therefore, if we see a short read here, it has occurred
// after the message has been completed, so it is safe to ignore it.
if(ec == net::ssl::error::stream_truncated)
return;
std::cerr << what << ": " << ec.message() << "\n";
}
// A simple helper for cancellation_slot
struct cancellation_signals
{
std::list<net::cancellation_signal> sigs;
std::mutex mtx;
void emit(net::cancellation_type ct = net::cancellation_type::all)
{
std::lock_guard<std::mutex> _(mtx);
for (auto & sig : sigs)
sig.emit(ct);
}
net::cancellation_slot slot()
{
std::lock_guard<std::mutex> _(mtx);
auto itr = std::find_if(sigs.begin(), sigs.end(),
[](net::cancellation_signal & sig)
{
return !sig.slot().has_handler();
});
if (itr != sigs.end())
return itr->slot();
else
return sigs.emplace_back().slot();
}
};
//------------------------------------------------------------------------------
// Echoes back all received WebSocket messages.
// This uses the Curiously Recurring Template Pattern so that
// the same code works with both SSL streams and regular sockets.
template<class Derived>
class websocket_session
{
// Access the derived class, this is part of
// the Curiously Recurring Template Pattern idiom.
Derived&
derived()
{
return static_cast<Derived&>(*this);
}
beast::flat_buffer buffer_;
// Start the asynchronous operation
template<class Body, class Allocator>
void
do_accept(http::request<Body, http::basic_fields<Allocator>> req)
{
// Set suggested timeout settings for the websocket
derived().ws().set_option(
websocket::stream_base::timeout::suggested(
beast::role_type::server));
// Set a decorator to change the Server of the handshake
derived().ws().set_option(
websocket::stream_base::decorator(
[](websocket::response_type& res)
{
res.set(http::field::server,
std::string(BOOST_BEAST_VERSION_STRING) +
" advanced-server-flex");
}));
// Accept the websocket handshake
derived().ws().async_accept(
req,
beast::bind_front_handler(
&websocket_session::on_accept,
derived().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
derived().ws().async_read(
buffer_,
beast::bind_front_handler(
&websocket_session::on_read,
derived().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)
return fail(ec, "read");
// Echo the message
derived().ws().text(derived().ws().got_text());
derived().ws().async_write(
buffer_.data(),
beast::bind_front_handler(
&websocket_session::on_write,
derived().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();
}
public:
// Start the asynchronous operation
template<class Body, class Allocator>
void
run(http::request<Body, http::basic_fields<Allocator>> req)
{
// Accept the WebSocket upgrade request
do_accept(std::move(req));
}
};
//------------------------------------------------------------------------------
// Handles a plain WebSocket connection
class plain_websocket_session
: public websocket_session<plain_websocket_session>
, public std::enable_shared_from_this<plain_websocket_session>
{
websocket::stream<beast::tcp_stream> ws_;
public:
// Create the session
explicit
plain_websocket_session(
beast::tcp_stream&& stream)
: ws_(std::move(stream))
{
}
// Called by the base class
websocket::stream<beast::tcp_stream>&
ws()
{
return ws_;
}
};
//------------------------------------------------------------------------------
// Handles an SSL WebSocket connection
class ssl_websocket_session
: public websocket_session<ssl_websocket_session>
, public std::enable_shared_from_this<ssl_websocket_session>
{
websocket::stream<
beast::ssl_stream<beast::tcp_stream>> ws_;
public:
// Create the ssl_websocket_session
explicit
ssl_websocket_session(
beast::ssl_stream<beast::tcp_stream>&& stream)
: ws_(std::move(stream))
{
}
// Called by the base class
websocket::stream<
beast::ssl_stream<beast::tcp_stream>>&
ws()
{
return ws_;
}
};
//------------------------------------------------------------------------------
template<class Body, class Allocator>
void
make_websocket_session(
beast::tcp_stream stream,
http::request<Body, http::basic_fields<Allocator>> req)
{
std::make_shared<plain_websocket_session>(
std::move(stream))->run(std::move(req));
}
template<class Body, class Allocator>
void
make_websocket_session(
beast::ssl_stream<beast::tcp_stream> stream,
http::request<Body, http::basic_fields<Allocator>> req)
{
std::make_shared<ssl_websocket_session>(
std::move(stream))->run(std::move(req));
}
//------------------------------------------------------------------------------
// Handles an HTTP server connection.
// This uses the Curiously Recurring Template Pattern so that
// the same code works with both SSL streams and regular sockets.
template<class Derived>
class http_session
{
std::shared_ptr<std::string const> doc_root_;
// Access the derived class, this is part of
// the Curiously Recurring Template Pattern idiom.
Derived&
derived()
{
return static_cast<Derived&>(*this);
}
static constexpr std::size_t queue_limit = 8; // max responses
std::vector<http::message_generator> response_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_;
protected:
beast::flat_buffer buffer_;
public:
// Construct the session
http_session(
beast::flat_buffer buffer,
std::shared_ptr<std::string const> const& doc_root)
: doc_root_(doc_root)
, buffer_(std::move(buffer))
{
}
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.
beast::get_lowest_layer(
derived().stream()).expires_after(std::chrono::seconds(30));
// Read a request using the parser-oriented interface
http::async_read(
derived().stream(),
buffer_,
*parser_,
beast::bind_front_handler(
&http_session::on_read,
derived().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 derived().do_eof();
if(ec)
return fail(ec, "read");
// See if it is a WebSocket Upgrade
if(websocket::is_upgrade(parser_->get()))
{
// Disable the timeout.
// The websocket::stream uses its own timeout settings.
beast::get_lowest_layer(derived().stream()).expires_never();
// Create a websocket session, transferring ownership
// of both the socket and the HTTP request.
return make_websocket_session(
derived().release_stream(),
parser_->release());
}
// Send the response
queue_write(handle_request(*doc_root_, parser_->release()));
// If we aren't at the queue limit, try to pipeline another request
if (response_queue_.size() < queue_limit)
do_read();
}
void
queue_write(http::message_generator response)
{
// Allocate and store the work
response_queue_.push_back(std::move(response));
// If there was no previous work, start the write
// loop
if (response_queue_.size() == 1)
do_write();
}
// Called to start/continue the write-loop. Should not be called when
// write_loop is already active.
//
// Returns `true` if the caller may initiate a new read
bool
do_write()
{
bool const was_full =
response_queue_.size() == queue_limit;
if(! response_queue_.empty())
{
http::message_generator msg =
std::move(response_queue_.front());
response_queue_.erase(response_queue_.begin());
bool keep_alive = msg.keep_alive();
beast::async_write(
derived().stream(),
std::move(msg),
beast::bind_front_handler(
&http_session::on_write,
derived().shared_from_this(),
keep_alive));
}
return was_full;
}
void
on_write(
bool keep_alive,
beast::error_code ec,
std::size_t bytes_transferred)
{
boost::ignore_unused(bytes_transferred);
if(ec)
return fail(ec, "write");
if(! keep_alive)
{
// This means we should close the connection, usually because
// the response indicated the "Connection: close" semantic.
return derived().do_eof();
}
// Inform the queue that a write completed
if(do_write())
{
// Read another request
do_read();
}
}
};
//------------------------------------------------------------------------------
// Handles a plain HTTP connection
class plain_http_session
: public http_session<plain_http_session>
, public std::enable_shared_from_this<plain_http_session>
{
beast::tcp_stream stream_;
public:
// Create the session
plain_http_session(
beast::tcp_stream&& stream,
beast::flat_buffer&& buffer,
std::shared_ptr<std::string const> const& doc_root)
: http_session<plain_http_session>(
std::move(buffer),
doc_root)
, stream_(std::move(stream))
{
}
// Start the session
void
run()
{
this->do_read();
}
// Called by the base class
beast::tcp_stream&
stream()
{
return stream_;
}
// Called by the base class
beast::tcp_stream
release_stream()
{
return std::move(stream_);
}
// Called by the base class
void
do_eof()
{
// Send a TCP shutdown
beast::error_code ec;
stream_.socket().shutdown(tcp::socket::shutdown_send, ec);
// At this point the connection is closed gracefully
}
};
//------------------------------------------------------------------------------
// Handles an SSL HTTP connection
class ssl_http_session
: public http_session<ssl_http_session>
, public std::enable_shared_from_this<ssl_http_session>
{
beast::ssl_stream<beast::tcp_stream> stream_;
public:
// Create the http_session
ssl_http_session(
beast::tcp_stream&& stream,
ssl::context& ctx,
beast::flat_buffer&& buffer,
std::shared_ptr<std::string const> const& doc_root)
: http_session<ssl_http_session>(
std::move(buffer),
doc_root)
, stream_(std::move(stream), ctx)
{
}
// Start the session
void
run()
{
// Set the timeout.
beast::get_lowest_layer(stream_).expires_after(std::chrono::seconds(30));
// Perform the SSL handshake
// Note, this is the buffered version of the handshake.
stream_.async_handshake(
ssl::stream_base::server,
buffer_.data(),
beast::bind_front_handler(
&ssl_http_session::on_handshake,
shared_from_this()));
}
// Called by the base class
beast::ssl_stream<beast::tcp_stream>&
stream()
{
return stream_;
}
// Called by the base class
beast::ssl_stream<beast::tcp_stream>
release_stream()
{
return std::move(stream_);
}
// Called by the base class
void
do_eof()
{
// Set the timeout.
beast::get_lowest_layer(stream_).expires_after(std::chrono::seconds(30));
// Perform the SSL shutdown
stream_.async_shutdown(
beast::bind_front_handler(
&ssl_http_session::on_shutdown,
shared_from_this()));
}
private:
void
on_handshake(
beast::error_code ec,
std::size_t bytes_used)
{
if(ec)
return fail(ec, "handshake");
// Consume the portion of the buffer used by the handshake
buffer_.consume(bytes_used);
do_read();
}
void
on_shutdown(beast::error_code ec)
{
if(ec)
return fail(ec, "shutdown");
// At this point the connection is closed gracefully
}
};
//------------------------------------------------------------------------------
// Detects SSL handshakes
class detect_session : public std::enable_shared_from_this<detect_session>
{
beast::tcp_stream stream_;
ssl::context& ctx_;
std::shared_ptr<std::string const> doc_root_;
beast::flat_buffer buffer_;
public:
explicit
detect_session(
tcp::socket&& socket,
ssl::context& ctx,
std::shared_ptr<std::string const> const& doc_root)
: stream_(std::move(socket))
, ctx_(ctx)
, doc_root_(doc_root)
{
}
// Launch the detector
void
run()
{
// We need to be executing within a strand to perform async operations
// on the I/O objects in this session. Although not strictly necessary
// for single-threaded contexts, this example code is written to be
// thread-safe by default.
net::dispatch(
stream_.get_executor(),
beast::bind_front_handler(
&detect_session::on_run,
this->shared_from_this()));
}
void
on_run()
{
// Set the timeout.
stream_.expires_after(std::chrono::seconds(30));
beast::async_detect_ssl(
stream_,
buffer_,
beast::bind_front_handler(
&detect_session::on_detect,
this->shared_from_this()));
}
void
on_detect(beast::error_code ec, bool result)
{
if(ec)
return fail(ec, "detect");
if(result)
{
// Launch SSL session
std::make_shared<ssl_http_session>(
std::move(stream_),
ctx_,
std::move(buffer_),
doc_root_)->run();
return;
}
// Launch plain session
std::make_shared<plain_http_session>(
std::move(stream_),
std::move(buffer_),
doc_root_)->run();
}
};
template<typename Stream>
net::awaitable<void, executor_type> do_eof(Stream & stream)
{
beast::error_code ec;
stream.socket().shutdown(tcp::socket::shutdown_send, ec);
co_return ;
}
template<typename Stream>
BOOST_ASIO_NODISCARD net::awaitable<void, executor_type>
do_eof(beast::ssl_stream<Stream> & stream)
{
co_await stream.async_shutdown();
}
template<typename Stream, typename Body, typename Allocator>
BOOST_ASIO_NODISCARD net::awaitable<void, executor_type>
run_websocket_session(Stream & stream,
beast::flat_buffer & buffer,
http::request<Body, http::basic_fields<Allocator>> req,
const std::shared_ptr<std::string const> & doc_root)
{
beast::websocket::stream<Stream&> ws{stream};
// 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-flex");
}));
// Accept the websocket handshake
auto [ec] = co_await ws.async_accept(req);
if (ec)
co_return fail(ec, "accept");
while (true)
{
// Read a message
std::size_t bytes_transferred = 0u;
std::tie(ec, bytes_transferred) = co_await ws.async_read(buffer);
// This indicates that the websocket_session was closed
if (ec == websocket::error::closed)
co_return;
if (ec)
co_return fail(ec, "read");
ws.text(ws.got_text());
std::tie(ec, bytes_transferred) = co_await ws.async_write(buffer.data());
if (ec)
co_return fail(ec, "write");
// Clear the buffer
buffer.consume(buffer.size());
}
}
template<typename Stream>
BOOST_ASIO_NODISCARD net::awaitable<void, executor_type>
run_session(Stream & stream, beast::flat_buffer & buffer, const std::shared_ptr<std::string const> & doc_root)
{
http::request_parser<http::string_body> parser;
// Apply a reasonable limit to the allowed size
// of the body in bytes to prevent abuse.
parser.body_limit(10000);
auto [ec, bytes_transferred] = co_await http::async_read(stream, buffer, parser);
if(ec == http::error::end_of_stream)
co_await do_eof(stream);
if(ec)
co_return fail(ec, "read");
// this can be
// while ((co_await net::this_coro::cancellation_state).cancelled() == net::cancellation_type::none)
// on most compilers
for (auto cs = co_await net::this_coro::cancellation_state;
cs.cancelled() == net::cancellation_type::none;
cs = co_await net::this_coro::cancellation_state)
{
if(websocket::is_upgrade(parser.get()))
{
// Disable the timeout.
// The websocket::stream uses its own timeout settings.
beast::get_lowest_layer(stream).expires_never();
co_await run_websocket_session(stream, buffer, parser.release(), doc_root);
co_return ;
}
// we follow a different strategy then the other example: instead of queue responses,
// we always to one read & write in parallel.
auto res = handle_request(*doc_root, parser.release());
if (!res.keep_alive())
{
http::message_generator msg{std::move(res)};
auto [ec, sz] = co_await beast::async_write(stream, std::move(msg));
if (ec)
fail(ec, "write");
co_return ;
}
http::message_generator msg{std::move(res)};
auto [_, ec_r, sz_r, ec_w, sz_w ] =
co_await net::experimental::make_parallel_group(
http::async_read(stream, buffer, parser, net::deferred),
beast::async_write(stream, std::move(msg), net::deferred))
.async_wait(net::experimental::wait_for_all(),
net::as_tuple(net::use_awaitable_t<executor_type>{}));
if (ec_r)
co_return fail(ec_r, "read");
if (ec_w)
co_return fail(ec_w, "write");
}
}
BOOST_ASIO_NODISCARD net::awaitable<void, executor_type>
detect_session(typename beast::tcp_stream::rebind_executor<executor_with_default>::other stream,
net::ssl::context & ctx,
std::shared_ptr<std::string const> doc_root)
{
beast::flat_buffer buffer;
// Set the timeout.
stream.expires_after(std::chrono::seconds(30));
// on_run
auto [ec, result] = co_await beast::async_detect_ssl(stream, buffer);
// on_detect
if (ec)
co_return fail(ec, "detect");
if(result)
{
using stream_type = typename beast::tcp_stream::rebind_executor<executor_with_default>::other;
beast::ssl_stream<stream_type> ssl_stream{std::move(stream), ctx};
auto [ec, bytes_used] = co_await ssl_stream.async_handshake(net::ssl::stream_base::server, buffer.data());
if(ec)
co_return fail(ec, "handshake");
buffer.consume(bytes_used);
co_await run_session(ssl_stream, buffer, doc_root);
}
else
co_await run_session(stream, buffer, doc_root);
}
bool init_listener(typename tcp::acceptor::rebind_executor<executor_with_default>::other & acceptor,
const tcp::endpoint &endpoint)
{
beast::error_code ec;
// Open the acceptor
acceptor.open(endpoint.protocol(), ec);
if(ec)
{
fail(ec, "open");
return false;
}
// Allow address reuse
acceptor.set_option(net::socket_base::reuse_address(true), ec);
if(ec)
{
fail(ec, "set_option");
return false;
}
// Bind to the server address
acceptor.bind(endpoint, ec);
if(ec)
{
fail(ec, "bind");
return false;
}
// Start listening for connections
acceptor.listen(
net::socket_base::max_listen_connections, ec);
if(ec)
{
fail(ec, "listen");
return false;
}
return true;
}
// Accepts incoming connections and launches the sessions.
BOOST_ASIO_NODISCARD net::awaitable<void, executor_type>
listen(ssl::context& ctx,
tcp::endpoint endpoint,
std::shared_ptr<std::string const> doc_root,
cancellation_signals & sig)
{
typename tcp::acceptor::rebind_executor<executor_with_default>::other acceptor{co_await net::this_coro::executor};
if (!init_listener(acceptor, endpoint))
co_return;
while ((co_await net::this_coro::cancellation_state).cancelled() == net::cancellation_type::none)
{
auto [ec, sock] = co_await acceptor.async_accept();
const auto exec = sock.get_executor();
using stream_type = typename beast::tcp_stream::rebind_executor<executor_with_default>::other;
if (!ec)
// We dont't need a strand, since the awaitable is an implicit strand.
net::co_spawn(exec,
detect_session(stream_type(std::move(sock)), ctx, doc_root),
net::bind_cancellation_slot(sig.slot(), net::detached));
}
}
//------------------------------------------------------------------------------
int main(int argc, char* argv[])
{
// Check command line arguments.
if (argc != 5)
{
std::cerr <<
"Usage: advanced-server-flex-awaitable <address> <port> <doc_root> <threads>\n" <<
"Example:\n" <<
" advanced-server-flex-awaitable 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};
// The SSL context is required, and holds certificates
ssl::context ctx{ssl::context::tlsv12};
// This holds the self-signed certificate used by the server
load_server_certificate(ctx);
// Cancellation-signal for SIGINT
cancellation_signals cancellation;
// Create and launch a listening routine
net::co_spawn(
ioc,
listen(ctx, tcp::endpoint{address, port}, doc_root, cancellation),
net::bind_cancellation_slot(cancellation.slot(), net::detached));
// Capture SIGINT and SIGTERM to perform a clean shutdown
net::signal_set signals(ioc, SIGINT, SIGTERM);
signals.async_wait(
[&](beast::error_code const&, int sig)
{
if (sig == SIGINT)
cancellation.emit(net::cancellation_type::all);
else
{
// 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;
}
#else
int main(int, char * [])
{
std::printf("awaitables require C++20\n");
return 1;
}
#endif