How to limit connection in Linux socket programming?

Question

I want to set the maximum of connection. If it more than the maximum, tell the client now server is full and close the socket.

How to write code in C ?

Thank you.

Answer 1

Simple. At the point where you call accept(), something like this:

new_conn = accept(listen_sock, &addr, addr_len);

if (new_conn > 0)
{
    if (total_connections < max_connections)
    {
        total_connections++;
        register_connection(new_conn);
    }
    else
    {
        send_reject_msg(new_conn);
        close(new_conn);
    }
}

(and of course decrement total_connections at the point where you lose a connection).