libs/beast/example/http/server/coro/http_server_coro.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: HTTP server, coroutine
//
//------------------------------------------------------------------------------
#include <boost/beast/core.hpp>
#include <boost/beast/http.hpp>
#include <boost/beast/version.hpp>
#include <boost/asio/ip/tcp.hpp>
#include <boost/asio/detached.hpp>
#include <boost/asio/spawn.hpp>
#include <boost/config.hpp>
#include <algorithm>
#include <cstdlib>
#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 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;
}
// 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)
{
std::cerr << what << ": " << ec.message() << "\n";
}
// Handles an HTTP server connection
void
do_session(
beast::tcp_stream& stream,
std::shared_ptr<std::string const> const& doc_root,
net::yield_context yield)
{
beast::error_code ec;
// This buffer is required to persist across reads
beast::flat_buffer buffer;
// This lambda is used to send messages
for(;;)
{
// Set the timeout.
stream.expires_after(std::chrono::seconds(30));
// Read a request
http::request<http::string_body> req;
http::async_read(stream, buffer, req, yield[ec]);
if(ec == http::error::end_of_stream)
break;
if(ec)
return fail(ec, "read");
// Handle the request
http::message_generator msg =
handle_request(*doc_root, std::move(req));
// Determine if we should close the connection
bool keep_alive = msg.keep_alive();
// Send the response
beast::async_write(stream, std::move(msg), yield[ec]);
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.
break;
}
}
// Send a TCP shutdown
stream.socket().shutdown(tcp::socket::shutdown_send, ec);
// At this point the connection is closed gracefully
}
//------------------------------------------------------------------------------
// Accepts incoming connections and launches the sessions
void
do_listen(
net::io_context& ioc,
tcp::endpoint endpoint,
std::shared_ptr<std::string const> const& doc_root,
net::yield_context yield)
{
beast::error_code ec;
// Open the acceptor
tcp::acceptor acceptor(ioc);
acceptor.open(endpoint.protocol(), ec);
if(ec)
return fail(ec, "open");
// Allow address reuse
acceptor.set_option(net::socket_base::reuse_address(true), ec);
if(ec)
return fail(ec, "set_option");
// Bind to the server address
acceptor.bind(endpoint, ec);
if(ec)
return fail(ec, "bind");
// Start listening for connections
acceptor.listen(net::socket_base::max_listen_connections, ec);
if(ec)
return fail(ec, "listen");
for(;;)
{
tcp::socket socket(ioc);
acceptor.async_accept(socket, yield[ec]);
if(ec)
fail(ec, "accept");
else
boost::asio::spawn(
acceptor.get_executor(),
std::bind(
&do_session,
beast::tcp_stream(std::move(socket)),
doc_root,
std::placeholders::_1),
// we ignore the result of the session,
// most errors are handled with error_code
boost::asio::detached);
}
}
int main(int argc, char* argv[])
{
// Check command line arguments.
if (argc != 5)
{
std::cerr <<
"Usage: http-server-coro <address> <port> <doc_root> <threads>\n" <<
"Example:\n" <<
" http-server-coro 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};
// Spawn a listening port
boost::asio::spawn(ioc,
std::bind(
&do_listen,
std::ref(ioc),
tcp::endpoint{address, port},
doc_root,
std::placeholders::_1),
// on completion, spawn will call this function
[](std::exception_ptr ex)
{
// if an exception occurred in the coroutine,
// it's something critical, e.g. out of memory
// we capture normal errors in the ec
// so we just rethrow the exception here,
// which will cause `ioc.run()` to throw
if (ex)
std::rethrow_exception(ex);
});
// 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();
return EXIT_SUCCESS;
}