This is a simple package that basically adds two things to plain UDP sockets:
Multiplexing: multiple 'endpoints' on a single UDP socket;
Reliability: UDP packets are fragmented to stay under the network's MTU as far as possible and each fragment is retransmitted until an ACK is received (or some timer expires).
Wire format:
All datagrams are sent as 1 or more fragments
A fragment has the following wire format:
1 byte magic code: 16rAA;
1 byte protocol version: 1;
1 byte fragment type:
0=regular fragment
1=ACK fragment
2=reliable fragment
4 bytes datagram id;
2 bytes fragment number;
2 bytes number of fragments;
2 bytes endpoint;
0 - (max fragment size - fragment header size) bytes of data (currently 1000 - 23 = 987 bytes).
If a reliable fragment is received, an ACK fragment with the same header but minus the data is sent back. The reliable sending process attempts retransmits until each fragment is acknowledged.
