TCP网络编程中多线程的客户端实现（linux下）

悠悠 2022-01-25 14:50 264阅读 0赞

示例如下：

#include <sys/socket.h>
    #include <sys/types.h>
    #include <unistd.h>
    #include <arpa/inet.h>
    #include <netinet/in.h>
    #include <errno.h>
    #include <strings.h>
    #include <ctype.h>
    #include <sys/wait.h>
    #include <signal.h>
    
    
    void sig_child(int signo)
    {
            while(waitpid(-1,NULL,WNOHANG) > 0);
            return ;
    }
    
    
    int port = 8000;
    int main()
    {
            struct sockaddr_in sin,pin;
            int sock_descriptor,temp_sock_descriptor;
            socklen_t address_size;
            int i ,len,pid,on =1;
            char buf[16384];
    
            signal(SIGCHLD,sig_child);
    
            sock_descriptor = socket(AF_INET,SOCK_STREAM,0);
            bzero(&sin,sizeof(sin));
            sin.sin_family = AF_INET;
            sin.sin_addr.s_addr = INADDR_ANY;
            sin.sin_port = htons(port);
            setsockopt(sock_descriptor,SOL_SOCKET,SO_REUSEADDR,&on,sizeof(on));
            if( bind(sock_descriptor,(struct sockaddr *)&sin,sizeof(sin)) == -1 )
            {
                    perror("call to bind\n");
                    exit(1);
            }
            if(listen(sock_descriptor,20) == -1)
            {
                    perror("call to listen\n");
                    exit(1);
            }
            printf("accepting connections...\n");
    
            while(1)
            {
                    temp_sock_descriptor = accept(sock_descriptor,(struct sockaddr *)&pin,&address_size);
                    if( (pid = fork()) < 0 )
                    {
                            perror("fork");
                            exit(1);
                    }
                    else if(pid == 0)
                    {//child
                            close(sock_descriptor);
                            if(recv(temp_sock_descriptor,buf,16384,0) == -1)
                            {
                                    perror("call to recv\n");
                                    exit(1);
                            }
                            printf("received from client :%s\n",buf);
    
    
                            len = strlen(buf);
                            for( i  = 0 ; i < len ; i++)
                            {
                                    buf[i] = toupper(buf[i]);
                            }
                            if(send(temp_sock_descriptor,buf,len+1,0) == -1)
                            {
                                    perror("call to send \n");
                                    exit(1);
                            }
                            sleep(60);
                            close(temp_sock_descriptor);
                            exit(0);
                    }
                    close(temp_sock_descriptor);
            }
    
    
    
    }

注意：

1、由于父进程并不需要连接套接字，所以需要在父进程中关闭。同理，子进程不需要监听套接字，因此在子进程中关闭。

2、子进程在结束时会向父进程递送SIGCHLD信号，所以在父进程中捕获SIGCHLD信号，并在该信号处理程序中调用waitpid，从而防止僵尸进程的产生。