linux的基础知识——多进程并发服务器

1.实现一个多进程的并发服务器

#include<stdio.h>
#include<unistd.h>
#include<stdlib.h>
#include<arpa/inet.h>
#include<strings.h>
#include<ctype.h>
#include<sys/socket.h>
#include<sys/types.h>
#include<signal.h>
#include<sys/wait.h>

#define SERV_IP "192.168.0.2"
#define SERV_PORT 8888

void wait_child(int signo)
{
    
    
        while(waitpid(0,NULL,WNOHANG)>0);
        return;
}

int main()
{
    
    
        pid_t pid;
        int lfd,cfd;
        struct sockaddr_in serv_addr,clie_addr;
        socklen_t clie_addr_len;
        char buf[BUFSIZ],clie_IP[BUFSIZ];
        int n,i,ret;

        lfd = socket(AF_INET,SOCK_STREAM,0);
        if(lfd==-1){
    
    
                perror("socket error");
                exit(1);
        }


        bzero(&serv_addr,sizeof(serv_addr));

        serv_addr.sin_family = AF_INET;
        serv_addr.sin_port = htons(SERV_PORT);
        //inet_pton(AF_INET,SERV_IP,&serv_addr.sin_addr.s_addr);
        serv_addr.sin_addr.s_addr = htonl(INADDR_ANY);

        ret = bind(lfd,(struct sockaddr *)&serv_addr,sizeof(serv_addr));
        if(ret==-1){
    
    
                perror("bind error");
                exit(1);
        }  

        ret = listen(lfd,128);
        if(ret==-1){
    
    
                perror("listen error");
                exit(1);
        }
        
        while(1){
    
    
                clie_addr_len = sizeof(clie_addr);
                cfd = accept(lfd,(struct sockaddr *)&clie_addr,&clie_addr_len);
                if(cfd==-1){
    
    
                        perror("accept error");
                        exit(1);
                }
                printf("client IP:%s,port:%d\n",
                        inet_ntop(AF_INET,&clie_addr.sin_addr.s_addr,clie_IP,sizeof(clie_IP)),ntohs(clie_addr.sin_port));
                pid = fork();
                if(pid<0){
    
    
                        perror("fork error");
                        exit(1);
                }
                else if(pid == 0){
    
    
                        close(lfd);
                        while(1){
    
    
                                n = read(cfd,buf,sizeof(buf));
                                if(n==0){
    
    
                                        close(cfd);
                                        return 0;
                                }
                                else if(n==-1){
    
    
                                        perror("read error");
                                        exit(1);
                                }
                                else{
    
    
                                        for(i=0;i<n;i++){
    
    
                                                        buf[i] = toupper(buf[i]);
                                                }

                                        write(cfd,buf,n);
                                }
                        }
                }
                else{
    
    
                        close(cfd);
                        signal(SIGCHLD,wait_child);
                }
        }
        return 0;
}