Update readme

lib/networking/backend/README.md

@@ -1,3 +1,41 @@
 # I-MIC FPS / CyberarmEngine Networking System
 End Goal: Reliable and ordered packets of abitrary size
-Current Goal: Unreliable, unordered packets of limited size
+
+Current Goal: Unreliable, unordered packets of limited size
+
+## Internal Packet Format
+Based on [minetest's network protocol](https://dev.minetest.net/Network_Protocol)
+### Base header
+All packet headers start with these fields
+```
+Protocol Version: Unsigned char
+Packet Type: Unsigned char
+Peer ID: Unsigned char
+```
+
+### Basic packet header
+No unique header fields
+
+### Control packet header
+```
+Control Type: Unsigned char
+Control Data: Unsigned 16-bit integer
+```
+Control Types:
+* ACK - Acknowledge receipt of reliable packet
+* SET_PEER_ID - Set peer id of connected client, client must provide this to continue communicating
+* PING - Used to track peer's network latency
+* HEARTBEAT - Used as keep alive
+* DISCONNECT - Peer is disconnecting
+
+### Split Packet Header
+```
+Sequence Number: Unsigned 16-bit number
+Chunk Count: Unsigned 16-bit number
+Chunk Number: Unsigned 16-bit number
+```
+
+### Reliable Packet Header
+```
+Sequence Number: Unsigned 16-bit number
+```