Reliable Communication over Unreliable Channel. -- 2

One UDP socket through which all actual communication happen. Two threads R and S. Thread R handles all messages received from the UDP socket, and thread S, handles the timeouts and retransmissions. More details of R and S are given below. Two tables, unacknowledged-message table and received-message table. The first table contains the list of all messages that have been sent but not yet acknowledged by the receiver, along with the last sending time of the message. The second table contains all messages received in the socket