After some digging, I found out the Origin field of RumorMessage might contain the identifier in the Origin field.
However, how are we suppose to known the identifier of the sender of a StatusPacket to see if he has some unknown message of us. Don't we need to know the identifier of the sender of this StatusPacket.
If we create a structure to store the messages received from the different nodes and we index those using their identifier("Origin field") as stated in the handout we won't be able to know the host identifier when we receive it's StatusMessage. Therefore I do not see how I could use the identifier to keep track of the messages I receive. Should we instead keep track of the messages received using the IP address instead of the Identifiers ?