Question

请帮帮我

客户：

#include<stdio.h> //printf
#include<string.h>    //strlen
#include<sys/socket.h>    //socket
#include<arpa/inet.h> //inet_addr 
int main(int argc , char *argv[])
{
    int sock;
    struct sockaddr_in server;
    char message[1000] , server_reply[2000];

    //Create socket
    sock = socket(AF_INET , SOCK_STREAM , 0);
    if (sock == -1)
    {
        printf("Could not create socket");
    }
    puts("Socket created");

    server.sin_addr.s_addr = inet_addr("127.0.0.1");
    server.sin_family = AF_INET;
    server.sin_port = htons( 8888 );

    //Connect to remote server
    if (connect(sock , (struct sockaddr *)&server , sizeof(server)) < 0)
    {
        perror("connect failed. Error");
        return 1;
    }

    puts("Connected\n");

    //keep communicating with server
    while(1)
    {
        printf("Enter message : ");
        scanf("%s" , message);

        //Send some data
        if( send(sock , message , strlen(message) , 0) < 0)
        {
            puts("Send failed");
            return 1;
        }
        memset(message,0,sizeof(message));
          //Receive a reply from the server 
    }

    close(sock);
    return 0;
}

服务器：

#include<stdio.h>
#include<string.h>    //strlen
#include<sys/socket.h>
#include<arpa/inet.h> //inet_addr
#include<unistd.h>    //write

int main(int argc , char *argv[])
{
    int socket_desc , client_sock , c , read_size;
    struct sockaddr_in server , client;
    char client_message[2000];

    //Create socket
    socket_desc = socket(AF_INET , SOCK_STREAM , 0);
    if (socket_desc == -1)
    {
        printf("Could not create socket");
    }
    puts("Socket created");

    //Prepare the sockaddr_in structure
    server.sin_family = AF_INET;
    server.sin_addr.s_addr = INADDR_ANY;
    server.sin_port = htons( 8888 );

    //Bind
    if( bind(socket_desc,(struct sockaddr *)&server , sizeof(server)) < 0)
    {
        //print the error message
        perror("bind failed. Error");
        return 1;
    }
    puts("bind done");

    //Listen
    listen(socket_desc , 3);

    //Accept and incoming connection
    puts("Waiting for incoming connections...");
    c = sizeof(struct sockaddr_in);

    //accept connection from an incoming client
    client_sock = accept(socket_desc, (struct sockaddr *)&client, (socklen_t*)&c);
    if (client_sock < 0)
    {
        perror("accept failed");
        return 1;
    }
    puts("Connection accepted");

    //Receive a message from client
    while( (read_size = recv(client_sock , client_message , 2000 , 0)) > 0 )
    {
    if(read_size == 0)
    {
        puts("Client disconnected");
        fflush(stdout);
    }
    else if(read_size == -1)
    {
        perror("recv failed");
    }
        //Send the message back to client
       puts(client_message);
       fflush(stdout);
    }



    return 0;
}

来自网站的源代码。我尝试并成功连接并发送消息。问题是我将客户端连接到服务器。然后我用ctrl + c关闭服务器。我尝试发送消息，为什么我的消息发送成功？（当服务器结束时）。但是，当我再次尝试发送消息时，连接结束。请帮我。我想只发送一次，连接结束。不是两次。

Answer 1

这会发生什么：您的代码退出是因为引发了SIG_PIPE以指示发送错误。你没有信号捕获器，因此默认操作是静默退出！

试试这个send(sock , message , strlen(message) ,MSG_NOSIGNAL)并阅读信号

Answer 2

但是如何只发送一次，连接结束（服务器关闭ctrl + c）？不要两次发送。

虽然您的客户端没有recv()呼叫，但在服务器终止后第一次send()呼叫后，您仍然可以通过获取待处理的套接字立即检测到 Broken pipe getsockopt(…, SOL_SOCKET, SO_ERROR, …)错误，如this answer to "How to find the socket connection state in C?"中所示如果以这种方式返回错误，您可以break循环和close()套接字。

linux socket c：当其他socket关闭时发送数据

2 个答案: