【Socket 编程】基于UDP协议建立多人聊天室

思路

对于服务端来说，除了要接收消息之外，还要实现一个路由转发模块，该路由转发模块可以将相应发送给所有连接的客户端。而对于客户端来说，除了要发送消息给聊天室，还要能实时看到其它所有客户端的消息。
下面来看看具体实现的代码，代码只给出核心模块，其余代码模块代码可以借鉴我之前的博客。具体来说，服务器类实现的功能只有收消息。

路由功能实现

Route.hpp头文件

该头文件实现了一个路由类，该路由类维护了一张用户表和一把锁。该类向外提供转发消息功能的接口。为了实现并发转发消息，这里使用到了之前博客写的线程池，将转发功能的函数提供给线程池里的线程去处理。

#pragma once
#include <iostream>
#include <string>
#include <vector>
#include <functional>
#include <sys/types.h>
#include <sys/socket.h>
#include <pthread.h>
#include <cstring>
#include "InetAddr.hpp"
#include "ThreadPool.hpp"#include "LockGuard.hpp"
using namespace std;
using task_t = function<void()>;class Route
{
private:
public:Route(){pthread_mutex_init(&_mutex, nullptr);}void CheckOnlineUser(InetAddr &who){// 用户表是临界资源，需要加锁LockGuard lockguard(&_mutex);for (auto &user : _online_user){if (user == who){LOG(DEBUG, "%s is exists!\n", who.AddrStr().c_str());return;}}LOG(DEBUG, "%s is not exists,add it!\n", who.AddrStr().c_str());_online_user.push_back(who);}// 下线void Offline(InetAddr &who){LockGuard lockguard(&_mutex);vector<InetAddr>::iterator st = _online_user.begin();while (st != _online_user.end()){if (*st == who){_online_user.erase(st);LOG(DEBUG, "%s is offline\n", who.AddrStr().c_str());break;}st++;}}void ForwardHelper(int sockfd, const string &message, InetAddr who){LockGuard lockguard(&_mutex);string send_message = "[" + who.AddrStr() + "]# " + message;// 遍历在线用户表，转发给他们for (auto &user : _online_user){struct sockaddr_in peer = user.Addr();LOG(DEBUG, "Forward message to %s\n", user.AddrStr().c_str());sendto(sockfd, send_message.c_str(), send_message.size(), 0, (struct sockaddr *)&peer, sizeof(peer));}}// 转发消息给在线用户表void Forward(int sockfd, const string &message, InetAddr &who){// 查看该用户是否在线，不在线就添加到在线用户中CheckOnlineUser(who);// 如果用户退出if (message == "QUIT" || message == "quit"){// 下线Offline(who);return;}// 创建单例线程池帮助转发task_t t = bind(&Route::ForwardHelper, this, sockfd, message, who);ThreadPool<task_t>::GetInstance()->Push(t);}~Route(){pthread_mutex_destroy(&_mutex);}private:vector<InetAddr> _online_user; // 在线用户表pthread_mutex_t _mutex;
};

服务端

UdpServerMain.cpp

服务器的处理逻辑

#include "UdpServer.hpp"
#include <iostream>
#include <string>
#include <memory>
#include "Route.hpp"
using namespace std;int main(int argc, char *argv[])
{if (argc != 2){cerr << "Usage:" << argv[0] << " local-port" << endl;exit(0);}uint16_t port = stoi(argv[1]);EnableScreen();Route messageRoute;server_t message_route = bind(&Route::Forward,&messageRoute, std::placeholders::_1, std::placeholders::_2, std::placeholders::_3);std::unique_ptr<UdpServer> usvr = std::make_unique<UdpServer>(message_route, port); // C++14的标准usvr->InitServer();usvr->Start();return 0;
}

UdpServer.hpp

实现一个服务器类

#pragma once
#include <iostream>
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <string>
#include <cstring>
#include "LockGuard.hpp"
#include "Log.hpp"
#include "nocopy.hpp"
#include "InetAddr.hpp"
#include <functional>
using namespace log_ns;
using namespace std;
static const int gsockfd = -1;
static const uint16_t glocalport = 8888;
using server_t = function<void(int, const string &, InetAddr &)>;
enum
{SOCKET_ERROR = 1,BIND_ERROR
};class UdpServer : public nocopy
{
private:
public:UdpServer(server_t func, uint16_t localport = glocalport): _localport(localport), _isrunning(false), _sockfd(gsockfd), _fun(func){}void InitServer(){// 创建socket_sockfd = socket(AF_INET, SOCK_DGRAM, 0); // IPv4协议和UDP协议的套接字if (_sockfd < 0){LOG(FATAL, "socket create error!\n");exit(1);}LOG(DEBUG, "socket create success,sockfd is %d\n", _sockfd);// 绑定端口号和IP// 绑定之前创建一个sockaddr_in对象,存储本地地址信息struct sockaddr_in local;memset(&local, 0, sizeof(local));local.sin_family = AF_INET;local.sin_addr.s_addr = INADDR_ANY; // 服务器端，进行任意IP地址绑定local.sin_port = htons(_localport);int n = bind(_sockfd, (struct sockaddr *)&local, sizeof(local));if (n < 0){LOG(FATAL, "sockfd bind error!\n");exit(1);}LOG(DEBUG, "sockfd bind success!\n");}void Start(){_isrunning = true;char inbuff[1024];while (_isrunning){// 获取数据struct sockaddr_in peer;socklen_t len = sizeof(peer);ssize_t n = recvfrom(_sockfd, inbuff, sizeof(inbuff) - 1, 0, (struct sockaddr *)&peer, &len);if (n < 0){LOG(FATAL, "recvfrom error!\n");}else{LOG(DEBUG, "recvfrom success!\n");InetAddr addr(peer);inbuff[n] = '\0';std::string message = inbuff;_fun(_sockfd, message, addr);}}_isrunning = false;}~UdpServer(){if (_sockfd >= 0)close(_sockfd);}private:int _sockfd;uint16_t _localport;bool _isrunning;server_t _fun;
};

客户端

UdpClientMain.cpp

该文件实现了客户端发送消息和接收消息的逻辑，由于发送消息和接收消息需要异步进行，所以可以考虑使用两个线程，分别查看聊天室的消息和向聊天室发送消息

#include <iostream>
#include <string>
#include <cstring>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include "Thread.hpp"
#include "InetAddr.hpp"
#include <memory>
#include <functional>
using namespace std;
using namespace ThreadMoudle;int InitClient()
{int sockfd = socket(AF_INET, SOCK_DGRAM, 0);if (sockfd < 0){cerr << "create client failed" << endl;exit(1);}return sockfd;
}// 发送消息
void SendMessage(int sockfd, string serverip, uint16_t serverport, const string &name)
{// 客户端一般不用绑定套接字，操作系统会在第一次发送消息时自动绑定本机ip和一个随机的portstruct sockaddr_in server;memset(&server, 0, sizeof(server));server.sin_family = AF_INET;server.sin_addr.s_addr = inet_addr(serverip.c_str());server.sin_port = htons(serverport);while (true){string line;cout << name << " #: ";getline(cin, line);ssize_t res = sendto(sockfd, line.c_str(), line.size(), 0, (struct sockaddr *)&server, sizeof(server));if (res <= 0){break;}}
}// 接收消息
void RecvMessage(int sockfd, const string &name)
{while (true){struct sockaddr_in peer;char buff[1024];socklen_t len = 0;int n = recvfrom(sockfd, buff, sizeof(buff) - 1, 0, (struct sockaddr *)&peer, &len);if (n > 0){buff[n] = 0;cout << buff << endl;}else{cerr << "recvfrom error\n"<< endl;break;}}
}int main(int argc, char *argv[])
{if (argc != 3){cerr << "Usage:" << argv[0] << " local-port" << endl;exit(0);}string ip = argv[1];uint16_t port = stoi(argv[2]);int sockfd = InitClient();// auto ref = std::bind(&RecvMessage, sockfd, placeholders::_1);//  auto senf = std::bind(&SendMessage, sockfd, ip, port, placeholders::_1, placeholders::_2, placeholders::_3);Thread recver("recver-thread", std::bind(&RecvMessage, sockfd, std::placeholders::_1));Thread sender("sender-thread", std::bind(&SendMessage, sockfd, ip, port, std::placeholders::_1));recver.Start();sender.Start();recver.Join();sender.Join();close(sockfd);return 0;
}