简单Linux网络编程Echo实现回射。

简单Linux网络编程实现回射。此处服务器端server.c

#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>

#define MYPORT 8887
#define QUEUE 20
#define BUFFER_SIZE 2048
void do_service(int conn) /*定义一个do_service结构体，进行输出和输入操作。*/
{
    char buffer[BUFFER_SIZE];
    while(1)
    {
        memset(buffer,0,sizeof(buffer)); /*初始化*/
        int len = recv(conn, buffer, sizeof(buffer),0);/*接收到的数据*/
        if(len==0)
        {
            printf("client close\n");
            break;
        }
        else if(len==-1)
        {
            perror("read");
        }
        fputs(buffer, stdout); /*标准输出*/
        send(conn, buffer, len, 0); /*标准发送*/
    }
}
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 = inet_addr("127.0.0.1");

    ///bind，成功返回0，出错返回-1
    int on =1;
    if(setsockopt(server_sockfd,SOL_SOCKET,SO_REUSEADDR,&on,sizeof(on))==-1) /*获得套接口信息*/
    {
         perror("setsockopt");
         exit(1);
    }
     printf("ip=%s port=%d\n",inet_ntoa(server_sockaddr.sin_addr),ntohs(server_sockaddr.sin_port));
    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
    int listenfd=listen(server_sockfd,QUEUE) ; /*建立监听*/
    if(listenfd<0)
    {
        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
   printf("accept ...\n");
    int conn ;
    pid_t pid;/*用fork（）创建子进程*/
    while(1) /*可以让多个客户端连接*/
    {     if((conn = accept(server_sockfd, (struct sockaddr*)&client_addr, &length))<0) /*conn 为接收套接字*/
     {
          perror("connect");
          exit(1);

         }


          pid =fork();
         if(pid==-1)
     {
            perror("fork");
            exit(1);
           }
         if(pid==0) /*子进程进行函数操作*/
         {
             close(server_sockfd);
             do_service(conn);
             exit(0);
         }
         else
             close(conn); /*父进程进行函数操作*/


    }
    return 0;
}

客户端client.c

#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>

#define MYPORT 8887
#define BUFFER_SIZE 2048

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)); /*初始化*/
    servaddr.sin_family = AF_INET; ///IPv4协议
    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);
    }
    printf("ip=%s port=%d\n",inet_ntoa(servaddr.sin_addr),ntohs(servaddr.sin_port));  ///输出服务器IP地址和端口

    char sendbuf[BUFFER_SIZE];
    char recvbuf[BUFFER_SIZE];
    while (fgets(sendbuf, sizeof(sendbuf), stdin) != NULL) ///键盘输入
    {
        send(sock_cli, sendbuf, strlen(sendbuf),0); ///发送
        recv(sock_cli, recvbuf, sizeof(recvbuf),0); ///接收
        fputs(recvbuf, stdout);

        memset(sendbuf, 0, sizeof(sendbuf));
        memset(recvbuf, 0, sizeof(recvbuf));
    }

    close(sock_cli);
    return 0;
}