Design a simple UDP-based protocol for retrieving files from a server. No authentication is to be provided. Stop-and-wait transmission of the data may be used. Your protocol should address the following issues:
(a) Duplication of the first packet should not duplicate the "connection."
(b) Loss of the final ACK should not necessarily leave the server in doubt as to whether the transfer succeeded.
(c) A late-arriving packet from a past connection shouldn't be interpretable as part of a current connection.