3.1.5.3 Processing a LEAVE Packet

When a LEAVE packet is received, the server MUST remove the entry for the client from the Active Client List (section 3.1.1.2), using the ClientId field (section 2.2.11) of the LEAVE packet to identify the client. If a client entry matching the ClientId is not found in Active Client List (section 3.1.1.2), the server MUST check and remove the entry from the Kick Client List (section 3.1.1.2).