Linux网络编程 基于TCP的多进程

客户端代码：

#include   
#include   
#include   
#include   
#include   
#include   
#include   
#include   

static usage(const char* proc)  
{  
    printf("%s [ip] [port\n]", proc);  
}  

int main(int argc, char** argv)  
{  
    if(argc != 3)  
    {  
        usage(argv[0]);  
        exit(1);  
    }  

    int sock = socket(AF_INET, SOCK_STREAM, 0);  
    struct sockaddr_in server;  
    if(sock < 0)  
    {  
        perror("socket");  
        return 1;  
    }  
    server.sin_family = AF_INET;  
    server.sin_addr.s_addr = inet_addr(argv[1]);  
    server.sin_port = htons(atoi(argv[2]));  

    if(connect(sock ,(struct sockaddr*)&server, sizeof(server) ) < 0)  
    {  
        perror("connect");  
        exit(4);  
    }  

    char buf[1024];  

    while(1)  
    {  
        printf("please input #: ");  
        fflush(stdout);  
        ssize_t sread = read(0, buf, sizeof(buf)-1);  
        if(sread > 0)  
        {  
            buf[sread-1] = 0;  
            write(sock, buf, strlen(buf));  
            printf("server $ %s\n", buf);  
            read(sock, buf, sizeof(buf) - 1);  
        }  

    }  



    close(sock);  
}  

服务端#include

#include    //  
#include   // socket()  bind()  
#include   
#include   
#include   
#include   
#include   


static void usage(const char* proc)  
{  
    printf("use help : %s [local_ip] [local_port]\n", proc);  
}  

// 创建并绑定一个socket  
int startup(const char* _ip, int _port)  
{  
    // 创建一个socket  
    int sock = socket(AF_INET, SOCK_STREAM, 0);  
    if (sock < 0)  
    {  
        perror("----sock----fail\n");  
        exit(-1);  
    }  

    // 绑定一个本地socket  
    struct sockaddr_in local;  
    local.sin_family = AF_INET;  
    local.sin_addr.s_addr = inet_addr(_ip);  
    local.sin_port = htons(_port);  

    if(bind(sock, (struct sockaddr*)&local, sizeof(local)) != 0)  
    {  
        perror("---bind---fail\n");  
        close(sock);  
        exit(-2);  
    }  

    if(listen(sock, 5) != 0)  
    {  
        perror("----listen----fail\n");  
        close(sock);  
        exit(-1);  
    }  

    return sock;          
}  

int main(int argc, char**argv)  
{  
    if(argc != 3)  
    {  
        usage(argv[0]);  
        return -1;  
    }  

    // 获取一个local socket  
    int listen_sock = startup(argv[1], atoi(argv[2]));  
    struct sockaddr_in client;  
    socklen_t len = sizeof(client);  

    char buf[1024];  
    while(1)  
    {  
        int new_sock = accept(listen_sock,(struct sockaddr*)&client, &len);  
        if(new_sock < 0)  
        {  
            perror("----accept----fail\n");  
            close(listen_sock);  
            exit(-5);  
        }  
        pid_t id = fork();  
        if(id == 0)  
        {  
            if(fork() > 0)  
            {  
                exit(0);  
            }   
            // ///////////////可以再这里fork 然后退出子进程,这样负责监听的进程PID就不会一直变//////////  
            close(listen_sock); // 子进程已经获得 sockfd， 不需要listen sock所以关闭  
            while(1)  
            {  
                ssize_t s = read(new_sock,buf, sizeof(buf)-1);  
                if(s > 0 )  
                {  
                    buf[s] = 0;  
                    printf("client say## %s \n", buf);  
                    write(new_sock, buf, strlen(buf));  
                }  
                else if( s == 0)  
                {  
                    printf("client quit. \n");  
                    break;  
                }  
                else  
                    break;  
            }  
            exit(0);  

        }  
        else if (id > 0)  
        {  
            // 父进程  
            // 在父进程中fork退出的话，会导致监听进程的pid一直在变，所以我们也可以再子进程中fork然后退出  
            close(new_sock); // 此时子进程已经获取 sockfd， 父进程只需要监听sockfd，又因为每次fork都会赋值描述符，为了节省资源，关闭new_sock  

        }  
    }  
    return 0;  
}