Linux上带有accept（）的分段错误

Question

I have a problem with a client/server programm on linux. I wrote a server programm wich is sending data cyclic to one conneted client. Now I want to detect, if the client close the connection to the server. When the connection is closed from the client, i want to wait with accept(...) for an new connection. Here the critical parts of my code:

error = send(client_sock, Zeichen, 1, MSG_NOSIGNAL);
if(error < 0)
{
    connected = 0;
    printf("Error, write on TCP Socket failed!!! Reconnecting... \r\n");
    close(serverSocket);
    initServer();
}

int initServer(void)
{
    int *new_sock;
    socklen_t size;
    struct sockaddr_in server, client;

    serverSocket = socket(AF_INET , SOCK_STREAM , 0);       //Create socket
    if (serverSocket == -1)
    {
      printf("Could not create socket \r\n");
      return 0;
    }else
    {
      printf("Socket created \r\n");
    }

    server.sin_addr.s_addr = inet_addr(IPAdresse);
    server.sin_family = AF_INET;
    server.sin_port = htons(TCPPort);

    if(bind(serverSocket,(struct sockaddr *)&server , sizeof(server)) < 0)  
    {
      printf("bind failed. Error \r\n");
      return 0;
    }else
    {
      printf("bind done \r\n");
    }

    listen(serverSocket, 1);        
    printf("Waiting for incoming connections... \r\n");
    size = sizeof(sockaddr_in);
    printf("size of sockaddr_in: %i \r\n", size);
    client_sock = accept(serverSocket, (struct sockaddr *)&client, &size);

   if (client_sock < 0)
   {
     printf("accept failed \r\n");
     return 0;
   }else
   {
    connected = 1;
    return 1;
   }
}

The first time it works fine, I can connect and can send data over the socket. When the client close the connection the error is detected, I close the socket an start the server again to wait for a new connection. But than I get a segmentation fault when I do the accept(..) for the second time!!! Can someone help me please!!! Thanks a lot!

Answer 1

It's not clear what you're doing when the client connection closes. I see no loop in your code, and yet you're suggesting that accept() is called more than once.

Without seeing the rest or the code, I can only speculate that:

• you're repeatedly calling initServer() , hence attempting to recreate the same server socket over and over (which, of course, would be bad),

or

• you're calling accept() again somewhere else in your code, most likely with corrupt arguments.

At the very least, what your server-side code should do is initialize the server socket once, then loop around accept() , like so:

• call socket() once
• call bind() once
• call listen() once
• then in a loop:
  • call accept() , this call will block until a client connects, and then return a connected socket,
  • do whatever you need to do with that (connected client) socket
  • resume with the loop