C多进程实现聊天服务

一、概述

　　案例：使用多进程实现聊天服务。要求：可以有多个客户端连接，且客户端发送什么数据服务端就回复什么数据

　　实现步骤：

　　1.创建监听文件描述符socket

　　2.绑定端口bind

　　3.监听端口listen

　　4.当接受到一个连接时开启一个子进程来实现，来实现和客户端的通讯(fork)

　　5.具体客户端通讯的方法read\write

二、代码示例

　　

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//多进程版网络服务器（优化版） #include <stdio.h> #include <stdlib.h> #include <sys/types.h> #include <string.h> #include <unistd.h> #include <arpa/inet.h> #include <netinet/in.h> #include <sys/wait.h> #include <signal.h> #include <ctype.h> #include "wrap.h"   //信号处理函数 void waitchild(int signo){         pid_t wpid;         while(1){                 wpid = waitpid(-1,NULL,WNOHANG);                 if(wpid>0){                         printf("child exit,wpid=[%d]\n",wpid);                 }else if(wpid==0||wpid==-1){                         break;                 }         } int main(){         //创建Socket         int lfd = Socket(AF_INET,SOCK_STREAM,0);         //设置端口复用         int opt;         setsockopt(lfd,SOL_SOCKET,SO_REUSEADDR,&opt,sizeof(int));         //绑定         struct sockaddr_in serv;         serv.sin_family = AF_INET;         serv.sin_port = htons(8888);         serv.sin_addr.s_addr = htonl(INADDR_ANY);         Bind(lfd,(struct sockaddr *)&serv,sizeof(serv));           //监听         Listen(lfd,128);           //阻塞信号         sigset_t mask;         sigemptyset(&mask);         sigaddset(&mask,SIGCHLD);         sigprocmask(SIG_BLOCK,&mask,NULL);           int cfd;         socklen_t len;         char sIP[16];         pid_t pid;         struct sockaddr_in client;         while(1){                 //等待客户端连接                 memset(sIP,0x00,sizeof(sIP));                 len = sizeof(client);                 bzero(&client,sizeof(client));                   cfd = Accept(lfd,(struct sockaddr *)&client,&len);                   //创建子进程                 pid = fork();                 if(pid<0){//创建进程失败                         perror("fork error");                         close(lfd);                         return -1;                 }else if(pid>0){//如果是父进程                                 //关闭通讯描述符                         close(cfd);                         //注册SIGCHLD信号处理函数                         struct sigaction act;                         act.sa_handler = waitchild;                         act.sa_flags = 0;                         sigemptyset(&act.sa_mask);                         //解除对SIGCHLD信号的阻塞                         sigprocmask(SIG_UNBLOCK,&mask,NULL);                 }else if(pid==0){//如果是子进程                         //关闭监听文件描述符                         close(lfd);                         int i =0;                         int n=0;                         char buf[1024];                         while(1){                                 memset(buf,0x00,sizeof(buf));                                 n = Read(cfd,buf,sizeof(buf));                                 if(n<=0){                                         printf("read error or client closed,n==[%d]\n",n);                                         break;                                 }                                 printf("read over,n==[%d],buf=[%s]\n",n,buf);                                 for(i=0;i<n;i++){                                         buf[i] = toupper(buf[i]);                                 }                                 write(cfd,buf,n);                         }                         close(cfd);                         exit(0);                 }             }         //关闭监听文件描述符         close(lfd);         return 0; }