network programming - How to find the socket connection state in C?

Question

I have a TCP connection. Server just reads data from the client. Now, if the connection is lost, the client will get an error while writing the data to the pipe (broken pipe), but the server still listens on that pipe. Is there any way I can find if the connection is UP or NOT?

Answer 1

You could call getsockopt just like the following:

int error = 0;
socklen_t len = sizeof (error);
int retval = getsockopt (socket_fd, SOL_SOCKET, SO_ERROR, &error, &len);

To test if the socket is up:

if (retval != 0) {
    /* there was a problem getting the error code */
    fprintf(stderr, "error getting socket error code: %s
", strerror(retval));
    return;
}

if (error != 0) {
    /* socket has a non zero error status */
    fprintf(stderr, "socket error: %s
", strerror(error));
}