@param base The event base to handle events for the server port.
@param socket A UDP socket to accept DNS requests.
@param flags Always 0 for now.
@param callback A function to invoke whenever we get a DNS request
on the socket.
@param user_data Data to pass to the callback.
@return an evdns_server_port structure for this server port.
Create a new DNS server port.
@param base The event base to handle events for the server port. @param socket A UDP socket to accept DNS requests. @param flags Always 0 for now. @param callback A function to invoke whenever we get a DNS request on the socket. @param user_data Data to pass to the callback. @return an evdns_server_port structure for this server port.