聊天服务器的设计，主要包括消息结构的设计，这个相对于网络更具有一样，通常避免粘包，都会设计成TLV的格式：
消息的头部Header主要包括消息的类型和消息体的长度，通过这样设计的原理是为了避免粘包时可以方便去解析数据
消息主要包括：bind name （client send）
chat info (client send)
room info (服务器分发)
设计如下：
structHeader.h
#ifndef FND_STRUCT_HEADER_H #define FND_STRUCT_HEADER_H #include <string> struct Header { int bodySize; int type; }; enum MessageType { MT_BIND_NAME = 1, // {"name" : "abc"} MT_CHAT_INFO = 2, // {"information" "what i say"} MT_ROOM_INFO = 3, // {"name" : "abc", "information" : "what i say"} }; // client send struct BindName { char name[32]; int nameLen; }; // client send struct ChatInformation { char information[256]; int infoLen; }; // serversend struct RoomInformation { BindName name; ChatInformation chat; }; bool parseMessage(const std::string &input, int *type, std::string &outbuffer); bool parseMessage2(const std::string &input, int *type, std::string &outbuffer); bool parseMessage3(const std::string &input, int *type, std::string &outbuffer); bool parseMessage4(const std::string &input, int *type, std::string &outbuffer); #endif
其中消息的传输类型主要包含原生的结构体，序列化(boost::serialization), json,protobuf等，
structHeader.cpp(实现)
#include "structHeader.h" #include "SerilizationObject.h" #include "JsonObject.h" #include "Protocal.pb.h" #include <cstdlib> #include <cstring> #include <iostream>
//boost serialization 序列化成字符串 template <typename T> std::string seriliaze(const T &obj) { std::stringstream ss; boost::archive::text_oarchive oa(ss); oa & obj; return ss.str(); } //通过protobuf的方式去序列化 bool parseMessage4(const std::string &input, int *type, std::string &outbuffer) { auto pos = input.find_first_of(" "); if (pos == std::string::npos) return false; if (pos == 0) return false; // "BindName ok" -> substr -> BindName auto command = input.substr(0, pos); if (command == "BindName") { // we try to bind name std::string name = input.substr(pos + 1); if (name.size() > 32) return false; if (type) *type = MT_BIND_NAME; PBindName bindName; bindName.set_name(name); //auto oldname = bindName.name(); auto ok = bindName.SerializeToString(&outbuffer); return ok; } else if (command == "Chat") { // we try to chat std::string chat = input.substr(pos + 1); if (chat.size() > 256) return false; PChat pchat; pchat.set_information(chat); auto ok = pchat.SerializeToString(&outbuffer); if (type) *type = MT_CHAT_INFO; return ok; } return false; } //通过json的方式序列化 bool parseMessage3(const std::string &input, int *type, std::string &outbuffer) { auto pos = input.find_first_of(" "); if (pos == std::string::npos) return false; if (pos == 0) return false; // "BindName ok" -> substr -> BindName auto command = input.substr(0, pos); if (command == "BindName") { // we try to bind name std::string name = input.substr(pos + 1); if (name.size() > 32) return false; if (type) *type = MT_BIND_NAME; ptree tree; tree.put("name", name); outbuffer = ptreeToJsonString(tree); //outbuffer = seriliaze(SBindName(std::move(name))); return true; } else if (command == "Chat") { // we try to chat std::string chat = input.substr(pos + 1); if (chat.size() > 256) return false; ptree tree; tree.put("information", chat); outbuffer = ptreeToJsonString(tree); //outbuffer = seriliaze(SChatInfo(std::move(chat))); if (type) *type = MT_CHAT_INFO; return true; } return false; } //boost serilize通过boost 进行序列化 bool parseMessage2(const std::string &input, int *type, std::string &outbuffer) { auto pos = input.find_first_of(" "); if (pos == std::string::npos) return false; if (pos == 0) return false; // "BindName ok" -> substr -> BindName auto command = input.substr(0, pos); if (command == "BindName") { // we try to bind name std::string name = input.substr(pos + 1); if (name.size() > 32) return false; if (type) *type = MT_BIND_NAME; //SBindName bindInfo(std::move(name)); outbuffer = seriliaze(SBindName(std::move(name))); return true; } else if (command == "Chat") { // we try to chat std::string chat = input.substr(pos + 1); if (chat.size() > 256) return false; outbuffer = seriliaze(SChatInfo(std::move(chat))); // ChatInformation info; // info.infoLen = chat.size(); // std::memcpy(&(info.information), chat.data(), chat.size()); // auto buffer = reinterpret_cast<const char *>(&info); // outbuffer.assign(buffer, buffer + sizeof(info)); if (type) *type = MT_CHAT_INFO; return true; } return false; } // 原生的消息处理方式 cmd messagebody bool parseMessage(const std::string &input, int *type, std::string &outbuffer) { // input should be cmd body auto pos = input.find_first_of(" "); if (pos == std::string::npos) return false; if (pos == 0) return false; // "BindName ok" -> substr -> BindName auto command = input.substr(0, pos); if (command == "BindName") { // we try to bind name std::string name = input.substr(pos + 1); if (name.size() > 32) return false; if (type) *type = MT_BIND_NAME; BindName bindInfo; bindInfo.nameLen = name.size(); std::memcpy(&(bindInfo.name), name.data(), name.size()); auto buffer = reinterpret_cast<const char *>(&bindInfo); outbuffer.assign(buffer, buffer + sizeof(bindInfo)); return true; } else if (command == "Chat") { // we try to chat std::string chat = input.substr(pos + 1); if (chat.size() > 256) return false; ChatInformation info; info.infoLen = chat.size(); std::memcpy(&(info.information), chat.data(), chat.size()); auto buffer = reinterpret_cast<const char *>(&info); outbuffer.assign(buffer, buffer + sizeof(info)); if (type) *type = MT_CHAT_INFO; return true; } return false; }
SerilizationObject.h（boost serilize的方式序列化）
#ifndef FND_SERI_H #define FND_SERI_H #include <boost/archive/text_oarchive.hpp> #include <boost/archive/text_iarchive.hpp> class SBindName { private: friend class boost::serialization::access; // When the class Archive corresponds to an output archive, the // & operator is defined similar to <<. Likewise, when the class Archive // is a type of input archive the & operator is defined similar to >>. template <class Archive> void serialize(Archive &ar, const unsigned int version) { ar & m_bindName; //ar << m_bindName; //ar >> m_bindName; } std::string m_bindName; public: SBindName(std::string name) : m_bindName(std::move(name)) {} SBindName() {} const std::string &bindName() const { return m_bindName; } }; class SChatInfo { friend class boost::serialization::access; // When the class Archive corresponds to an output archive, the // & operator is defined similar to <<. Likewise, when the class Archive // is a type of input archive the & operator is defined similar to >>. template <class Archive> void serialize(Archive &ar, const unsigned int version) { ar &m_chatInformation; } std::string m_chatInformation; public: SChatInfo(std::string info) : m_chatInformation(std::move(info)) {} SChatInfo() {} const std::string &chatInformation() const { return m_chatInformation; } }; class SRoomInfo { public: SRoomInfo() {} SRoomInfo(std::string name, std::string info) : m_bind(std::move(name)), m_chat(std::move(info)) {} const std::string& name() const { return m_bind.bindName();} const std::string& information() const { return m_chat.chatInformation();} private: friend class boost::serialization::access; template <class Archive> void serialize(Archive &ar, const unsigned int version) { ar &m_bind; ar & m_chat; } SBindName m_bind; SChatInfo m_chat; }; #endif
通过json的方式处理消息
JsonObject.h(将json转换为string)
#ifndef FND_JSON_OBJECT_H #define FND_JSON_OBJECT_H #include <sstream> #include <boost/property_tree/ptree.hpp> #include <boost/property_tree/json_parser.hpp> #include <string> using ptree = boost::property_tree::ptree; inline std::string ptreeToJsonString(const ptree& tree) { std::stringstream ss; boost::property_tree::write_json(ss, tree, false); return ss.str(); } #endif
通过protobuf处理，其中proto文件如下，可以通过proto文件去生成c++代码
syntax = 'proto3'; message PBindName { string name = 1; } message PChat { string information = 1; } message PRoomInformation { string name = 1; string information = 2; }
chat_message.h(主要包含消息头(type+bodysize) 和消息体(body)的解析)
#ifndef CHAT_MESSAGE_HPP #define CHAT_MESSAGE_HPP #include "structHeader.h" #include "SerilizationObject.h" #include <iostream> #include <cstdio> #include <cstdlib> #include <cstring> #include <cassert> // s -> c c -> s message { header, body } // header length class chat_message { public: enum { header_length = sizeof(Header) }; enum { max_body_length = 512 }; chat_message(){} const char *data() const { return data_; } char *data() { return data_; } std::size_t length() const { return header_length + m_header.bodySize; } const char *body() const { return data_ + header_length; } char *body() { return data_ + header_length; } int type() const { return m_header.type; } std::size_t body_length() const { return m_header.bodySize; } void setMessage(int messageType, const void *buffer, size_t bufferSize) { assert(bufferSize <= max_body_length); m_header.bodySize = bufferSize; m_header.type = messageType; std::memcpy(body(), buffer, bufferSize); std::memcpy(data(), &m_header, sizeof(m_header)); } void setMessage(int messageType, const std::string& buffer) { setMessage(messageType, buffer.data(), buffer.size()); } bool decode_header() { std::memcpy(&m_header, data(), header_length); if (m_header.bodySize > max_body_length) { std::cout << "body size " << m_header.bodySize << " " << m_header.type << std::endl; return false; } return true; } private: char data_[header_length + max_body_length]; Header m_header; }; #endif // CHAT_MESSAGE_HPP
其中server逻辑如下
server.cpp(其实这里可以优化，读一般会使用async_read_some（读一部分），写才使用，async_write（一定会写完指定的整个大小，底层会多次调用async_write_some）)
#include "chat_message.h" #include "JsonObject.h" #include "Protocal.pb.h" #include <boost/asio.hpp> #include <deque> #include <iostream> #include <list> #include <memory> #include <set> #include <utility> #include <cstdlib> using boost::asio::ip::tcp; //---------------------------------------------------------------------- using chat_message_queue = std::deque<chat_message>; using chat_message_queue2 = std::list<chat_message>; //---------------------------------------------------------------------- //---------------------------------------------------------------------- class chat_session; using chat_session_ptr = std::shared_ptr<chat_session>; class chat_room { public: public: void join(chat_session_ptr); void leave(chat_session_ptr); void deliver(const chat_message&); private: std::set<chat_session_ptr> participants_; enum { max_recent_msgs = 100 }; chat_message_queue recent_msgs_; }; //---------------------------------------------------------------------- class chat_session : public std::enable_shared_from_this<chat_session> { public: chat_session(tcp::socket socket, chat_room &room) : socket_(std::move(socket)), room_(room) {} void start() { room_.join(shared_from_this()); do_read_header(); } void deliver(const chat_message &msg) { // first false，避免多次调用写，因为写会一直循环从队列里面拿消息，一般都是将消息放到队列中处理，一次写完，包括回调全部完成，才去取消息，进行下一次写（如果混在一起会导致写回调和下一次写混在一起导致混乱） bool write_in_progress = !write_msgs_.empty(); write_msgs_.push_back(msg); if (!write_in_progress) { // first do_write(); } } private: void do_read_header() { auto self(shared_from_this()); boost::asio::async_read( socket_, boost::asio::buffer(read_msg_.data(), chat_message::header_length), [this, self](boost::system::error_code ec, std::size_t /*length*/) { if (!ec && read_msg_.decode_header()) { do_read_body(); } else { std::cout << "Player leave the room\n"; room_.leave(shared_from_this()); } }); } void do_read_body() { auto self(shared_from_this()); boost::asio::async_read( socket_, boost::asio::buffer(read_msg_.body(), read_msg_.body_length()), [this, self](boost::system::error_code ec, std::size_t /*length*/) { if (!ec) { //room_.deliver(read_msg_); handleMessage(); do_read_header(); } else { room_.leave(shared_from_this()); } }); } template <typename T> T toObject() { T obj; std::stringstream ss(std::string( read_msg_.body(), read_msg_.body() + read_msg_.body_length())); boost::archive::text_iarchive oa(ss); oa &obj; return obj; } bool fillProtobuf(::google::protobuf::Message* msg) { std::string ss( read_msg_.body(), read_msg_.body() + read_msg_.body_length()); auto ok = msg->ParseFromString(ss); return ok; } ptree toPtree() { ptree obj; std::stringstream ss( std::string(read_msg_.body(), read_msg_.body() + read_msg_.body_length())); boost::property_tree::read_json(ss, obj); return obj; } void handleMessage() { if (read_msg_.type() == MT_BIND_NAME) { PBindName bindName; if(fillProtobuf(&bindName)) m_name = bindName.name(); } else if (read_msg_.type() == MT_CHAT_INFO) { PChat chat; if(!fillProtobuf(&chat)) return; m_chatInformation = chat.information(); auto rinfo = buildRoomInfo(); chat_message msg; msg.setMessage(MT_ROOM_INFO, rinfo); room_.deliver(msg); } else { // not valid msg do nothing } } void do_write() { auto self(shared_from_this()); boost::asio::async_write( socket_, boost::asio::buffer(write_msgs_.front().data(), write_msgs_.front().length()), [this, self](boost::system::error_code ec, std::size_t /*length*/) { if (!ec) { write_msgs_.pop_front(); if (!write_msgs_.empty()) { do_write(); } } else { room_.leave(shared_from_this()); } }); } tcp::socket socket_; chat_room &room_; chat_message read_msg_; chat_message_queue write_msgs_; std::string m_name; std::string m_chatInformation; std::string buildRoomInfo() const { PRoomInformation roomInfo; roomInfo.set_name(m_name); roomInfo.set_information(m_chatInformation); std::string out; auto ok = roomInfo.SerializeToString(&out); assert(ok); return out; } // RoomInformation buildRoomInfo() const { // RoomInformation info; // info.name.nameLen = m_name.size(); // std::memcpy(info.name.name, m_name.data(), m_name.size()); // info.chat.infoLen = m_chatInformation.size(); // std::memcpy(info.chat.information, m_chatInformation.data(), // m_chatInformation.size()); // return info; // } }; void chat_room::join(chat_session_ptr participant) { participants_.insert(participant); for (const auto& msg : recent_msgs_) participant->deliver(msg); } void chat_room::leave(chat_session_ptr participant) { participants_.erase(participant); } void chat_room::deliver(const chat_message &msg) { recent_msgs_.push_back(msg); while (recent_msgs_.size() > max_recent_msgs) recent_msgs_.pop_front(); for (auto& participant : participants_) participant->deliver(msg); } //---------------------------------------------------------------------- class chat_server { public: chat_server(boost::asio::io_service &io_service, const tcp::endpoint &endpoint) : acceptor_(io_service, endpoint), socket_(io_service) { do_accept(); } private: void do_accept() { acceptor_.async_accept(socket_, [this](boost::system::error_code ec) { if (!ec) { auto session = std::make_shared<chat_session>(std::move(socket_), room_); session->start(); } do_accept(); }); } tcp::acceptor acceptor_; tcp::socket socket_; chat_room room_; }; //---------------------------------------------------------------------- int main(int argc, char *argv[]) { try { GOOGLE_PROTOBUF_VERIFY_VERSION; if (argc < 2) { std::cerr << "Usage: chat_server <port> [<port> ...]\n"; return 1; } boost::asio::io_service io_service; std::list<chat_server> servers; for (int i = 1; i < argc; ++i) { tcp::endpoint endpoint(tcp::v4(), std::atoi(argv[i])); servers.emplace_back(io_service, endpoint); } io_service.run(); } catch (std::exception &e) { std::cerr << "Exception: " << e.what() << "\n"; } google::protobuf::ShutdownProtobufLibrary(); return 0; }
其中client.cpp如下
#include "chat_message.h" #include "structHeader.h" #include "JsonObject.h" #include "SerilizationObject.h" #include "Protocal.pb.h" #include <boost/asio.hpp> #include <deque> #include <iostream> #include <thread> #include <cstdlib> #include <cassert> using boost::asio::ip::tcp; using chat_message_queue = std::deque<chat_message>; class chat_client { public: chat_client(boost::asio::io_service &io_service, tcp::resolver::iterator endpoint_iterator) : io_service_(io_service), socket_(io_service) { do_connect(endpoint_iterator); } void write(const chat_message &msg) { io_service_.post([this, msg]() { bool write_in_progress = !write_msgs_.empty(); write_msgs_.push_back(msg); if (!write_in_progress) { do_write(); } }); } void close() { io_service_.post([this]() { socket_.close(); }); } private: void do_connect(tcp::resolver::iterator endpoint_iterator) { boost::asio::async_connect( socket_, endpoint_iterator, [this](boost::system::error_code ec, tcp::resolver::iterator) { if (!ec) { do_read_header(); } }); } void do_read_header() { boost::asio::async_read( socket_, boost::asio::buffer(read_msg_.data(), chat_message::header_length), [this](boost::system::error_code ec, std::size_t /*length*/) { if (!ec && read_msg_.decode_header()) { do_read_body(); } else { socket_.close(); } }); } void do_read_body() { boost::asio::async_read( socket_, boost::asio::buffer(read_msg_.body(), read_msg_.body_length()), [this](boost::system::error_code ec, std::size_t /*length*/) { if (!ec) { if (read_msg_.type() == MT_ROOM_INFO) { //SRoomInfo info; std::string buffer(read_msg_.body(), read_msg_.body() + read_msg_.body_length()); PRoomInformation roomInfo; auto ok = roomInfo.ParseFromString(buffer); //if(!ok) throw std::runtime_error("not valid message"); //std::stringstream ss(buffer); //ptree tree; //boost::property_tree::read_json(ss, tree); if (ok) { std::cout << "client: '"; std::cout << roomInfo.name(); std::cout << "' says '"; std::cout << roomInfo.information(); std::cout << "'\n"; } // boost::archive::text_iarchive ia(ss); // ia & info; // std::cout << "client: '"; // std::cout << info.name(); // std::cout << "' says '"; // std::cout << info.information(); // std::cout << "'\n"; } do_read_header(); } else { socket_.close(); } }); } void do_write() { boost::asio::async_write( socket_, boost::asio::buffer(write_msgs_.front().data(), write_msgs_.front().length()), [this](boost::system::error_code ec, std::size_t /*length*/) { if (!ec) { write_msgs_.pop_front(); if (!write_msgs_.empty()) { do_write(); } } else { socket_.close(); } }); } private: boost::asio::io_service &io_service_; tcp::socket socket_; chat_message read_msg_; chat_message_queue write_msgs_; }; int main(int argc, char *argv[]) { try { GOOGLE_PROTOBUF_VERIFY_VERSION; if (argc != 3) { std::cerr << "Usage: chat_client <host> <port>\n"; return 1; } boost::asio::io_service io_service; tcp::resolver resolver(io_service); auto endpoint_iterator = resolver.resolve({argv[1], argv[2]}); chat_client c(io_service, endpoint_iterator); //将io_service放入单独的线程中，如果外部主线程需使用io_service处理异步读写消息，需要使用io_service.post std::thread t([&io_service]() { io_service.run(); }); char line[chat_message::max_body_length + 1]; // ctrl-d while (std::cin.getline(line, chat_message::max_body_length + 1)) { chat_message msg; auto type = 0; std::string input(line, line + std::strlen(line)); std::string output; if(parseMessage4(input, &type, output)) { msg.setMessage(type, output.data(), output.size()); c.write(msg);//外部线程需要使用io_service,需要post放入io_service处理队列进行分发处理 std::cout << "write message for server " << output.size() << std::endl; } } c.close();//需要post t.join(); } catch (std::exception &e) { std::cerr << "Exception: " << e.what() << "\n"; } google::protobuf::ShutdownProtobufLibrary(); return 0; }