文章目錄

• • 1 服務端升級為select模型處理多客戶端
  • • 1.1 概述
    • 1.2 服務端實現

1 服務端升級為select模型處理多客戶端

1.1 概述

之前我們的設計是服務端與客戶端1對1的阻塞模式網絡程序，我們這里對服務端進行升級，引入select模型，使得服務端有能力處理多個客戶端。

Socket的select模型：

int select (int nfds, fd_set FAR * readfds, fd_set FAR * writefds, fd_set FAR * exceptfds, const struct timeval FAR * timeout );

1.2 服務端實現

server.cpp：

#define WIN32_LEAN_AND_MEAN #define _WINSOCK_DEPRECATED_NO_WARNINGS#include<windows.h> #include<WinSock2.h> #include<stdio.h>#include <vector>#pragma comment(lib,"ws2_32.lib")enum CMD {CMD_LOGIN,CMD_LOGIN_RESULT,CMD_LOGOUT,CMD_LOGOUT_RESULT,CMD_ERROR };struct DataHeader {short dataLength;short cmd; };//DataPackage struct Login: public DataHeader {Login(){dataLength = sizeof(Login);cmd = CMD_LOGIN;}char userName[32];char PassWord[32]; };struct LoginResult : public DataHeader {LoginResult(){dataLength = sizeof(LoginResult);cmd = CMD_LOGIN_RESULT;result = 0;}int result; };struct Logout : public DataHeader {Logout(){dataLength = sizeof(Logout);cmd = CMD_LOGOUT;}char userName[32]; };struct LogoutResult : public DataHeader {LogoutResult(){dataLength = sizeof(LogoutResult);cmd = CMD_LOGIN_RESULT;result = 0;}int result; };std::vector<SOCKET> g_clients;int processor(SOCKET _cSock) {//緩沖區char szRecv[4096] = {};// 5 接收客戶端數據int nLen = recv(_cSock, szRecv, sizeof(DataHeader), 0);DataHeader* header = (DataHeader*)szRecv;if (nLen <= 0){printf("客戶端已退出，任務結束。\n");return -1;}switch (header->cmd){case CMD_LOGIN:{recv(_cSock, szRecv + sizeof(DataHeader), header->dataLength - sizeof(DataHeader), 0);Login* login = (Login*)szRecv;printf("收到命令：CMD_LOGIN,數據長度：%d,userName=%s PassWord=%s\n", login->dataLength, login->userName, login->PassWord);//忽略判斷用戶密碼是否正確的過程LoginResult ret;send(_cSock, (char*)&ret, sizeof(LoginResult), 0);}break;case CMD_LOGOUT:{recv(_cSock, szRecv + sizeof(DataHeader), header->dataLength - sizeof(DataHeader), 0);Logout* logout = (Logout*)szRecv;printf("收到命令：CMD_LOGOUT,數據長度：%d,userName=%s \n", logout->dataLength, logout->userName);//忽略判斷用戶密碼是否正確的過程LogoutResult ret;send(_cSock, (char*)&ret, sizeof(ret), 0);}break;default:{DataHeader header = { 0,CMD_ERROR };send(_cSock, (char*)&header, sizeof(header), 0);}break;} }int main() {//啟動Windows socket 2.x環境WORD ver = MAKEWORD(2, 2);WSADATA dat;WSAStartup(ver, &dat);//------------//-- 用Socket API建立簡易TCP服務端// 1 建立一個socket 套接字SOCKET _sock = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);// 2 bind 綁定用于接受客戶端連接的網絡端口sockaddr_in _sin = {};_sin.sin_family = AF_INET;_sin.sin_port = htons(4567);//host to net unsigned short_sin.sin_addr.S_un.S_addr = INADDR_ANY;//inet_addr("127.0.0.1");if (SOCKET_ERROR == bind(_sock, (sockaddr*)&_sin, sizeof(_sin))){printf("錯誤,綁定網絡端口失敗...\n");}else {printf("綁定網絡端口成功...\n");}// 3 listen 監聽網絡端口if (SOCKET_ERROR == listen(_sock, 5)){printf("錯誤,監聽網絡端口失敗...\n");}else {printf("監聽網絡端口成功...\n");}while (true){//伯克利 socketfd_set fdRead;fd_set fdWrite;fd_set fdExp;FD_ZERO(&fdRead);FD_ZERO(&fdWrite);FD_ZERO(&fdExp);FD_SET(_sock, &fdRead);FD_SET(_sock, &fdWrite);FD_SET(_sock, &fdExp);for (int n = (int)g_clients.size()-1; n >= 0 ; n--){FD_SET(g_clients[n], &fdRead);}///nfds 是一個整數值 是指fd_set集合中所有描述符(socket)的范圍，而不是數量///既是所有文件描述符最大值+1 在Windows中這個參數可以寫0timeval t = {0,0};int ret = select(_sock + 1, &fdRead, &fdWrite, &fdExp, &t);if (ret < 0){printf("select任務結束。\n");break;}if (FD_ISSET(_sock, &fdRead)){FD_CLR(_sock, &fdRead);// 4 accept 等待接受客戶端連接sockaddr_in clientAddr = {};int nAddrLen = sizeof(sockaddr_in);SOCKET _cSock = INVALID_SOCKET;_cSock = accept(_sock, (sockaddr*)&clientAddr, &nAddrLen);if (INVALID_SOCKET == _cSock){printf("錯誤,接受到無效客戶端SOCKET...\n");}g_clients.push_back(_cSock);printf("新客戶端加入：socket = %d,IP = %s \n", (int)_cSock, inet_ntoa(clientAddr.sin_addr));}for (size_t n = 0; n < fdRead.fd_count; n++){if (-1 == processor(fdRead.fd_array[n])){auto iter = find(g_clients.begin(), g_clients.end(), fdRead.fd_array[n]);if (iter != g_clients.end()){g_clients.erase(iter);}}}}for (size_t n = g_clients.size() - 1; n >= 0; n--){closesocket(g_clients[n]);}// 8 關閉套節字closesocketclosesocket(_sock);//------------//清除Windows socket環境WSACleanup();printf("已退出。\n");getchar();return 0; }

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參考資料：

C++ 百萬并發網絡通信引擎架構與實現 （服務端、客戶端、跨平臺） Version 1.0

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