beast网络库搭建http服务器
参考：https://llfc.club/category?catid=225RaiVNI8pFDD5L4m807g7ZwmF#!aid/2RlhDCg4eedYme46C6ddo4cKcFN
简介
前面的几篇文章已经介绍了如何使用asio搭建高并发的tcp服务器，以及http服务器。但是纯手写http服务器太麻烦了，有网络库beast已经帮我们实现了。这一期讲讲如何使用beast实现一个http服务器。
连接类
我们先实现http_server函数
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void http_server(tcp::acceptor& acceptor, tcp::socket& socket) { acceptor.async_accept(socket, [&](beast::error_code ec) { if (!ec) std::make_shared<http_connection>(std::move(socket))->start(); http_server(acceptor, socket); }); }
http_server中添加了异步接收连接的逻辑，当有新的连接到来时创建http_connection,然后启动服务，新连接监听对端数据。接下来http_server继续监听对端的新连接。
连接类http_connection里实现了start函数监听对端数据
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void start() { read_request(); check_deadline(); }
处理读请求,将读到的数据存储再成员变量request_中，然后调用process_request处理请求
void read_request() { auto self = shared_from_this(); http::async_read( socket_, buffer_, request_, [self](beast::error_code ec, std::size_t bytes_transferred) { boost::ignore_unused(bytes_transferred); if (!ec) self->process_request(); }); }
check_deadline主要时用来检测超时，当超过一定时间后自动关闭连接，因为http请求时短链接
void check_deadline() { auto self = shared_from_this(); deadline_.async_wait( [self](beast::error_code ec) { if (!ec) { // Close socket to cancel any outstanding operation. self->socket_.close(ec); } }); }
process_request函数中区分请求的类型，进行不同类型的处理如post还是get请求
void process_request() { response_.version(request_.version()); response_.keep_alive(false); switch (request_.method()) { case http::verb::get: response_.result(http::status::ok); response_.set(http::field::server, "Beast"); create_response(); break; case http::verb::post: response_.result(http::status::ok); response_.set(http::field::server, "Beast"); create_post_response(); break; default: // We return responses indicating an error if // we do not recognize the request method. response_.result(http::status::bad_request); response_.set(http::field::content_type, "text/plain"); beast::ostream(response_.body()) << "Invalid request-method '" << std::string(request_.method_string()) << "'"; break; } write_response(); }
create_response函数中解析了不同的路由处理get请求
void create_response() { if (request_.target() == "/count") { response_.set(http::field::content_type, "text/html"); beast::ostream(response_.body()) << "<html>\n" << "<head><title>Request count</title></head>\n" << "<body>\n" << "<h1>Request count</h1>\n" << "<p>There have been " << my_program_state::request_count() << " requests so far.</p>\n" << "</body>\n" << "</html>\n"; } else if (request_.target() == "/time") { response_.set(http::field::content_type, "text/html"); beast::ostream(response_.body()) << "<html>\n" << "<head><title>Current time</title></head>\n" << "<body>\n" << "<h1>Current time</h1>\n" << "<p>The current time is " << my_program_state::now() << " seconds since the epoch.</p>\n" << "</body>\n" << "</html>\n"; } else { response_.result(http::status::not_found); response_.set(http::field::content_type, "text/plain"); beast::ostream(response_.body()) << "File not found\r\n"; } }
create_post_response处理了post请求中的一部分路由
void create_post_response() { if (request_.target() == "/email") { auto& body = this->request_.body(); auto body_str = boost::beast::buffers_to_string(body.data()); std::cout << "receive body is " << body_str << std::endl; this->response_.set(http::field::content_type, "text/json"); Json::Value root; Json::Reader reader; Json::Value src_root; bool parse_success = reader.parse(body_str, src_root); if (!parse_success) { std::cout << "Failed to parse JSON data!" << std::endl; root["error"] = 1001; std::string jsonstr = root.toStyledString(); beast::ostream(this->response_.body()) << jsonstr; return ; } auto email = src_root["email"].asString(); std::cout << "email is " << email << std::endl; root["error"] = 0; root["email"] = src_root["email"]; root["msg"] = "recevie email post success"; std::string jsonstr = root.toStyledString(); beast::ostream(this->response_.body()) << jsonstr; } else { response_.result(http::status::not_found); response_.set(http::field::content_type, "text/plain"); beast::ostream(response_.body()) << "File not found\r\n"; } }
write_response发送请求
void write_response() { auto self = shared_from_this(); response_.content_length(response_.body().size()); http::async_write( socket_, response_, [self](beast::error_code ec, std::size_t) { self->socket_.shutdown(tcp::socket::shutdown_send, ec); self->deadline_.cancel(); }); }
