using the format PDU = {'header': {'msg_type' : 'text'}, 'body': text} use a CRC to check the message format - it is recommended you create a class object for the PDU to wrap all the common PDU functionality together. - in the header add a 'crc' key which will hold a 32bit CRC of the whole message (including the header) - The server should validate the CRC and send back an nack message if it fails - The server should close the connection after send 3 nack messages - The client should close the connection if it receives 3 nack messages - The nack message follows the same format as the ack message - Ensure the client and the server has suitable information displayed to the user