Many clients in UNIX Network Programming connect to the server and can reuse socket pairs.

Client and server program templates supported by network programming:

1. connect multiple clients to the server at the same time, that is, the service program can serve multiple clients at the same time;

2. The server supports socket pair reuse, that is, even in the time_wait status, the server can be restarted;

3. The server can check whether the client is disconnected;

4. The standard input of the client is displayed, and the server displays the content entered by the client from the standard output.

 

The program is as follows. Write down the template for reuse:

The client program is as follows:

/*************************************************************************    > File Name: p2pcli.c    > Author: ma6174    > Mail: [email protected]     > Created Time: Sun 05 Oct 2014 09:26:40 PM HKT ************************************************************************/#include<stdio.h>#include <errno.h>#include <stdlib.h>#include <unistd.h>#include <sys/types.h>#include <netinet/in.h>#include <string.h>#include <sys/socket.h>#include <arpa/inet.h>#define ERR_EXIT(m)         do         {             perror(m);             exit(EXIT_FAILURE);         }while(0)int main(int argc, char **argv){    int sockfd;    struct sockaddr_in servaddr;    if(argc != 2)    {        //printf("usage: p2pcli <IPaddress> ");        //exit(0);        ERR_EXIT("usage: p2pcli <IPaddress> ");    }    sockfd = socket(AF_INET, SOCK_STREAM, 0);    memset(&servaddr, 0, sizeof(servaddr));    servaddr.sin_family = AF_INET;    servaddr.sin_port = htons(5188);    servaddr.sin_addr.s_addr = inet_addr(argv[1]);    if(connect(sockfd, (struct sockaddr*)&servaddr, sizeof(servaddr)) < 0)    {        ERR_EXIT("connect");    }    //communication    char sendbuf[1024] = {0};    char recvbuf[1024] = {0};    while(fgets(sendbuf, sizeof(sendbuf), stdin) != NULL)    {        //send to server.        write(sockfd, sendbuf, strlen(sendbuf));        //read from server to display.        read(sockfd, recvbuf, sizeof(recvbuf));        //display        fputs(recvbuf, stdout);        memset(sendbuf, 0, sizeof(sendbuf));        memset(recvbuf, 0, sizeof(recvbuf));    }    close(sockfd);    return 0;}

The server program is as follows:

/*************************************************************************    > File Name: p2psrv.c    > Author: ma6174    > Mail: [email protected]     > Created Time: Sun 05 Oct 2014 08:27:06 PM HKT ************************************************************************/#include<stdio.h>#include <stdlib.h>#include <errno.h>#include <unistd.h>#include <sys/types.h>#include <netinet/in.h>#include <sys/socket.h>#include <string.h>#include <arpa/inet.h>#define ERR_EXIT(m)        do        {            perror(m);            exit(EXIT_FAILURE);        }while(0)void do_service(int connfd){    //communication    char recvbuf[1024];    while(1)    {        memset(recvbuf, 0, sizeof(recvbuf));        int ret = read(connfd, recvbuf, sizeof(recvbuf));        if(ret == 0)        {            printf("client close.\n");            break;        }        else if(ret == -1)        {            break;        }        else        {            fputs(recvbuf, stdout);            write(connfd, recvbuf, ret);        }    }}int main(){    int listenfd;    if( (listenfd = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP)) < 0)    {        ERR_EXIT("socket");    }    struct sockaddr_in servaddr;    memset(&servaddr, 0, sizeof(servaddr));    servaddr.sin_family = AF_INET;    servaddr.sin_port = htons(5188);    servaddr.sin_addr.s_addr = htonl(INADDR_ANY);    //reuse address    int on = 1;    if(setsockopt(listenfd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on)))    {        ERR_EXIT("setsockopt");    }    if(bind(listenfd, (struct sockaddr*)&servaddr, sizeof(servaddr)) < 0)    {        ERR_EXIT("bind");    }    if(listen(listenfd, SOMAXCONN) < 0)    {        ERR_EXIT("listen");    }    struct sockaddr_in peeraddr;    socklen_t peerlen = sizeof(peeraddr);    int connfd;    //muti client    pid_t pid;    while(1)    {        if( (connfd = accept(listenfd, (struct sockaddr*)&peeraddr, &peerlen)) < 0 )        {            ERR_EXIT("accept");        }        printf("ip=%s, port=%d\n", inet_ntoa(peeraddr.sin_addr), ntohs(peeraddr.sin_port));        pid = fork();        if(pid == -1)        {            ERR_EXIT("fork");        }        else if(pid == 0)        {            //child            close(listenfd);            do_service(connfd);            exit(0);        }        else        {            close(connfd);        }    }    close(connfd);    close(listenfd);    return 0;}

 

Many clients in UNIX Network Programming connect to the server and can reuse socket pairs.