From 0cd474601a480e6830a7f07b8c32383ed295a3b1 Mon Sep 17 00:00:00 2001
From: Sunpy <sunpy@osufx.com>
Date: Sat, 4 Apr 2020 23:12:24 +0200
Subject: [PATCH] Packet handling order of operations notes

---
 notes/packet_writeup.md | 19 +++++++++++++++++++
 sampy/client/player.py  | 12 ++++++------
 2 files changed, 25 insertions(+), 6 deletions(-)

diff --git a/notes/packet_writeup.md b/notes/packet_writeup.md
index 611b4ba..c788f02 100644
--- a/notes/packet_writeup.md
+++ b/notes/packet_writeup.md
@@ -11,6 +11,25 @@
 
 ## Shared
 * Can be internal packet
+* If packet is smaller then 3 bytes; forward to plugin handlers (*)before handling them (len(data) <= 2)
+
+## Order of operations
+1. Check if banned (if true, cancel rest and handle) [^1]
+2. If first byte in data is (0x19, 0x1d, 0x1f, 0x24 or 0x18) custom code flow required [^2]
+3. HandleSocketReceiveFromConnectedPlayer (cancel rest if handled)
+4. Check if cheat (modified) packet (unexpected at this time, there are some packets we can expect) [^3]
+
+[^1]: this could be changed in custom implementation (dont allow inital connection instead)
+[^2]: if (0x18 and length == 2) or (0x19 and length <= 2):  
+  handle packet and return  
+elif (0x1d or 0x1f or 0x24) and length <= 2:  
+  handle packet, but continue  
+[^3]: if ((0x18 or 0x1a) and length <= 3) or ((0x19 or 0x1d) and length <= 2) or
+    ((0x08 or 0x07 or 0x27) and length >= 5) or (0x37 and length < 400):  
+  We expect this packet, everything is ok?  
+else:  
+  This is a cheat (modified / injected) packet that should not arrive at this time
+  Send a packet to client that you received a modified packet (0x26)
 
 # Internal packet
 |condition|name|bit length|type|notes|
diff --git a/sampy/client/player.py b/sampy/client/player.py
index 04b6013..2de6713 100644
--- a/sampy/client/player.py
+++ b/sampy/client/player.py
@@ -8,16 +8,19 @@ logger = logging.getLogger(__name__)
 
 STATE_CONNECTING = 0
 STATE_AUTH = 1
+STATE_CONNECTED = 2
 
 class PlayerClient(BaseClient):
     def __init__(self, server: "__ServerInstance__", ip: str, port: int):
         super().__init__(server, ip, port)
         logger.debug("Client resolved to PlayerClient")
 
+        # TODO: check if banned and handle here
+
         self.state = STATE_CONNECTING
 
         self.handlers = {
-            0x18: self.on_connection_request,
+            STATE_CONNECTING: self.on_connection_request,
             #0x00: self.on_state_dependent_handle
         }
     
@@ -26,10 +29,7 @@ class PlayerClient(BaseClient):
 
         try:
             packet = self.server.compressor.decompress(packet)
-
-            
-
-            await self.handlers.get(packet[0], self.on_unimplemented)(packet)
+            await self.handlers.get(self.state, self.on_unimplemented)(packet)
         except Exception as err:
             logger.error(err)
     
@@ -54,7 +54,7 @@ class PlayerClient(BaseClient):
         
         logger.debug("challenge: passed")
         
-        self.state = STATE_AUTH
+        self.state = STATE_CONNECTED
         await self.send(b"\x19\x00") # Challenge passed
 
     async def parse_internal_packet(self, packet: bytes):