实现点对点聊天功能

实现点对点聊天功能。其中，signal函数实现对僵尸进程的处理。
server.c程序：

#include <sys/socket.h>
#include <stdio.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>
#include <fcntl.h>
#include <sys/shm.h>
#include<signal.h>
#define MYPORT 8887
#define QUEUE 20
#define BUFFER_SIZE 1024
void handler(int sig)   //信号的处理，避免出现僵尸进程。
{
    printf("recv a sig=%d\n",sig);
    exit(0);
}

int main()
{
    ///定义sockfd
    int server_sockfd = socket(AF_INET,SOCK_STREAM, 0);

    ///定义sockaddr_in
    struct sockaddr_in server_sockaddr;
    server_sockaddr.sin_family = AF_INET;
    server_sockaddr.sin_port = htons(MYPORT);
    server_sockaddr.sin_addr.s_addr = htonl(INADDR_ANY);

    ///bind，成功返回0，出错返回-1
    if(bind(server_sockfd,(struct sockaddr *)&server_sockaddr,sizeof(server_sockaddr))==-1)
    {
        perror("bind");
        exit(1);
    }

    ///listen，成功返回0，出错返回-1
    if(listen(server_sockfd,QUEUE) == -1)
    {
        perror("listen");
        exit(1);
    }

    ///客户端套接字

    struct sockaddr_in client_addr;
    socklen_t length = sizeof(client_addr);

    ///成功返回非负描述字，出错返回-1
    int conn = accept(server_sockfd, (struct sockaddr*)&client_addr, &length);
    if(conn<0)
    {
        perror("connect");
        exit(1);
    }
    pid_t pid;  //fork实现多进程
    pid =fork();
    if(pid ==-1)
       {
        perror("fork");
        exit(1);
       }
    if(pid ==0) //子进程
    {
        signal(SIGUSR1,handler);
        char sendbuf[BUFFER_SIZE] ={0};
        while (fgets(sendbuf,sizeof(sendbuf),stdin) !=NULL)
        {
             write(conn,sendbuf,strlen(sendbuf));
             memset(sendbuf,0,sizeof(sendbuf));
        }
        printf("child cose\n");
        exit(0);
    }
     else  //父进程
     {
         char buffer[BUFFER_SIZE];


           while(1)
          {
            memset(buffer,0,sizeof(buffer));
            int len = recv(conn, buffer, sizeof(buffer),0);
            if(len==-1) {
                perror("fork");
                exit(1);
                }
            else if(len ==0){
                printf("client close\n");
         break;
             }
         fputs(buffer, stdout);

          }
         printf("parent close\n");
         kill(pid,SIGUSR1);
         exit(0);
     }
    close(conn);
    close(server_sockfd);
    return 0;
}

client.c代码：

#include <sys/types.h>
#include <sys/socket.h>
#include <stdio.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>
#include <fcntl.h>
#include <sys/shm.h>
#include<signal.h>
#define MYPORT 8887
#define BUFFER_SIZE 1024
void handler(int sig) //信号处理功能
{
    printf("recv a sig=%d",sig);
    exit(0);
}
int main()
{
    ///定义sockfd
    int sock_cli = socket(AF_INET,SOCK_STREAM, 0);

    ///定义sockaddr_in
    struct sockaddr_in servaddr;
    memset(&servaddr, 0, sizeof(servaddr));
    servaddr.sin_family = AF_INET;
    servaddr.sin_port = htons(MYPORT); ///服务器端口
    servaddr.sin_addr.s_addr = inet_addr("127.0.0.1"); ///服务器ip

    ///连接服务器，成功返回0，错误返回-1
    if (connect(sock_cli, (struct sockaddr *)&servaddr, sizeof(servaddr)) < 0)
    {
        perror("connect");
        exit(1);
    }
     pid_t pid;
     pid =fork();
     if(pid ==-1)
        {
        perror("fork");
        exit(1);
         }
     if(pid ==0) //子进程
        {
         char recvbuf[BUFFER_SIZE];
         while(1)
         {
             memset(recvbuf,0,sizeof(recvbuf));
             int len =read(sock_cli,recvbuf,sizeof(recvbuf));
             if (len ==-1){
                perror("read");
                exit(1);
                }
                else if(len ==0)
                {
                    printf("client close\n");
                    break;
                }
                fputs(recvbuf,stdout);
         }
         close(socket);
         kill(getppid(),SIGUSR1);

     }
     else  //父进程
     {
            signal(SIGUSR1,handler);
         char sendbuf[BUFFER_SIZE] ={0};
            while (fgets(sendbuf, sizeof(sendbuf), stdin) != NULL)
            {
            send(sock_cli, sendbuf, strlen(sendbuf),0); ///发送
            memset(sendbuf, 0, sizeof(sendbuf));

            }
        close(socket);
        }



    return 0;
}