聊天程序实现

• 用多进程方式实现点对点聊天
  • 一个进程用来获得输入，一个进程用来获得对方发来的消息

客户端

//p2pcli.c
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <sys/types.h>
#include <unistd.h>
#include <errno.h>
#include <signal.h>

void handler(int sig)
{
    exit(EXIT_SUCCESS);
}

int main()
{
    int sock;
    //创建一个套接字
    if((sock = socket(AF_INET, SOCK_STREAM, 0)) < 0){
        perror("Creat socket failed.");
        exit(1);
    }
    /*int socket(int domain, int type, int protocol);*/
    struct sockaddr_in servaddr;
    memset(&servaddr, 0, sizeof(servaddr));
    servaddr.sin_family = AF_INET;
    servaddr.sin_port = htons(9000);
    servaddr.sin_addr.s_addr = inet_addr("127.0.0.1");
    /*servaddr.sin_addr.s_addr = inet_addr("127.0.0.1");*/
    /*inet_aton("127.0.0.1", &servaddr.sin_addr);*/
    if(connect(sock, (struct sockaddr*)&servaddr, sizeof(servaddr)) < 0){
        perror("connect() error");
        exit(1);
    }

    //

    pid_t pid;
    pid = fork();
    if(pid == -1){
        perror("fork() error");
    }
    if(pid == 0){
        //子进程接收对方发送的数据
        char recvbuf[1024] = {0};
        while(1){
            memset(recvbuf, 0, sizeof(recvbuf));
            int ret = read(sock, recvbuf, sizeof(recvbuf));
            if(ret == -1){
                perror("read() error");
                exit(1);
            } else if(ret == 0){
                printf("peer close\n");
                break;
            }
            fputs(recvbuf, stdout);
        }
        close(sock);
        kill(getppid(), SIGUSR1);//通知父进程退出
        exit(EXIT_SUCCESS);
    } else {
        //主进程发送数据

        signal(SIGUSR1, handler);
        char sendbuf[1024] = {0};
        while(fgets(sendbuf, sizeof(sendbuf), stdin) != NULL){
            write(sock, sendbuf, strlen(sendbuf));
            memset(sendbuf, 0, sizeof(sendbuf));
        }
        close(sock);
        exit(EXIT_SUCCESS);
    }

    return 0;
}

服务器端

//p2pserv.c
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <sys/types.h>
#include <unistd.h>
#include <errno.h>
#include <signal.h>

void handler(int sig)
{
    exit(EXIT_SUCCESS);
}

int main()
{
    int listenfd;
    //创建一个套接字
    if((listenfd = socket(AF_INET, SOCK_STREAM, 0)) < 0){
        perror("Create socket failed.");
        exit(1);
    }
    /*int socket(int domain, int type, int protocol);*/
    struct sockaddr_in servaddr;
    memset(&servaddr, 0, sizeof(servaddr));
    servaddr.sin_family = AF_INET;
    servaddr.sin_port = htons(9000);
    servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
    /*servaddr.sin_addr.s_addr = inet_addr("127.0.0.1");*/
    /*inet_aton("127.0.0.1", &servaddr.sin_addr);*/
    int on = 1;//选项开启标志
    //设置地址重复利用
    if(setsockopt(listenfd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on)) < 0){
        perror("setsockopt error.");
        exit(1);
    }

    if(bind(listenfd, (struct sockaddr*)&servaddr, sizeof(servaddr)) < 0){
        perror("bind error.");
        exit(1);
    }
    //绑定
    if(listen(listenfd, SOMAXCONN) < 0){
        perror("listen() error.");
        exit(1);
    }
    //监听

    struct sockaddr_in peeraddr;
    socklen_t peerlen = sizeof(peeraddr);
    int conn;
    if((conn = accept(listenfd, (struct sockaddr*)&peeraddr, &peerlen)) < 0){
        perror("accept() error");
        exit(1);
    }
    printf("ip = %s, port = %d\n", inet_ntoa(peeraddr.sin_addr), ntohs(peeraddr.sin_port));
    //
    pid_t pid;
    pid = fork();
    if(pid == -1){
        perror("fork() error");
        exit(1);
    }
    if(pid == 0){
        //发送数据的子进程

        signal(SIGUSR1, handler);
        char sendbuf[1024] = {0};
        while(fgets(sendbuf, sizeof(sendbuf), stdin) != NULL){
            write(conn, sendbuf, strlen(sendbuf));
            memset(sendbuf, 0, sizeof(sendbuf));
        }
        exit(EXIT_SUCCESS);
    } else {
        //父进程用于获取对方发送的数据
        char recvbuf[1024];
        while (1){
            memset(recvbuf, 0, sizeof(recvbuf));
            int ret = read(conn, recvbuf, sizeof(recvbuf));
             if(ret == -1){
                perror("read error");
                exit(1);
            } else if(ret == 0){
                printf("peer close\n");
                break;
            }
            fputs (recvbuf, stdout);
        }
        kill(pid, SIGUSR1);//通知子进程退出
        exit(EXIT_SUCCESS);
    }
    return 0;
}

实验结果