上一篇我們講的TCP伺服器的簡單實現是隻有一個程序連線的情況，但是實際上，這是不現實的，所以我們要改進我們的程式，使其可以服務於多個程序
直接上程式碼

server.c

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




void processrequest(int client_sock,struct sockaddr* client_socket)
{
    char buf[1024] = {0};
    ssize_t s = read(client_sock,buf,sizeof(buf));
    if(s < 0)
    {
        perror("read");
        continue;
    }
    if(s == 0)
    {
        //說明對端關閉
        printf("client %s say bye",inet_ntoa(client_socket->sin_addr));
        close(client_sock);
        break
 
;
    }
    buf[s] = '\0';
    printf("client:# %s",buf);
    printf("please wait...\n");
    write(client_sock,buf,sizeof(buf));

}
void createworker(int client_sock,struct sockaddr * client_socket)
{
    printf("get a new connect\n");
    pid_t pid = fork();
    if(pid < 0)
    {
        printf("fork error\n"
 
);
        return;
    }
    else if(pid == 0)
    {
        if(fork() == 0)
        {
            processrequest(client_sock,&client_socket);
        }
        exit(0);
    }
    else
    {
        waitpid(pid,NULL,0);
    }
}
int main(int argc,char *argv[])
{
    if(argv != 3)
    {
        printf("usage is ./server IP PORT\n");
        return 1;
    }
    int sock = socket(AF_INET,SOCK_STREAM,0);
    if(sock < 0)
    {
        printf("socket error\n");
        close(sock);
        return 2;
    }
    struct sockaddr_in server_socket;
    bzero(&server_socket,sizeof(server_socket));
    server_socket.sin_family = AF_INET;
    server_socket.sin_port = htons(atoi(argv[2]));
    server_socket.sin_addr.s_addr = inet_addr(argv[1]);
    if(bind(sock,(struct sockaddr*)&server_socket,sizeof(struct sockaddr_in) < 0)
    {
        printf("bind error\n");
        close(sock);
        return 2;
    }
    if(listen(sock,_BACKLOG_) < 0)
    {
        printf("listen error\n");
        close(sock);
        return 3;
    }
    printf("bind and listen is success,please wait accept...\n");

    while(1)
    {
        struct sockaddr_in client_socket;
        socklen_t len = 0;
        int client_sock = accept(sock,(struct sockaddr*)&client_socket,&len);
        //int accept(int sockfd,struct sockaddr *addr,socklen_t *addrlen);
        //addrlen引數是一個傳入傳出引數，傳入的是呼叫者提供的，緩衝區addr的長度以避免緩衝區溢位問題，
        //傳出的是客戶端地址結構體的實際長度（有可能沒有佔滿呼叫者提供的緩衝區）；
        if(client_sock < 0)
        {
            printf("accept error\n");
            close(sock);
            return 4;
        }
        createworker(client_sock,&client_socket)//結構體client_socket傳參用指標

    }

}

client.c

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

int main(int argc,char *argv)
{
    if(argc != 3)
    {
        printf("usage is ./client IP PORT");
        return 1;
    }
    int sock = socket(AF_INET,SOCK_STREAM,0);
    if(sock < 0)
    {
        perror("socket");
        return 2;
    }
    struct sockaddr_in server_sock;
    bzero(&server_sock,sizeof(server_sock));
    server_sock.sin_family = AF_INET;
    server_sock.sin_port = htons(atoi(argv[2]));
    server_sock.sin_addr.s_addr = inet_addr(argv[1]);

    int ret = connect(sock,(struct sockaddr*)&server_sock,sizeof(server_sock));
    if(ret < 0)
    {
        perror("connect");
        return 3;
    }
    pintf("connect is success!\n");
    while(1)
    {
        char buf[1024] = {0};
        printf("client #:");
        fflush(0);
        read(0,buf,strlen(buf));
        buf[strlen(buf)-1] = '\0';
        write(sock,buf,strlen(buf));
        if(strncasecmp(buf,"quit",4) == 0);
        {
            printf("client quit\n");
            break;
        }
        printf("please wait...\n");
        read(sock,buf,sizeof(buf));
        printf("server $:%s\n");

    }
    close(sock);
    return 0;   
}