More detailed logging of fragmented packets and those failing l4filter

Author: Monarda

snowsignal/packet.py

@@ -48,6 +48,10 @@ class Packet:
     ip_chksum: int | None = None
     ip_src_addr: str | None = None
     ip_dst_addr: str | None = None
+    ip_length: int | None = None
+    ipv4_identification: int | None = None
+    ipv4_more_fragments: bool = False
+    ipv4_fragmented_offset: int | None = None
 
     udp_src_port: int | None = None
     udp_dst_port: int | None = None
@@ -93,6 +97,14 @@ def _decode_ipv4(self) -> None:
         if self.ip_version != 4:
             return
 
+        self.ip_length = iph[2]
+        self.ipv4_identification = iph[3]
+
+        # Decode fragment data
+        fragment_flag_and_offset = iph[4]
+        self.ipv4_more_fragments = bool(fragment_flag_and_offset & 0x2000)
+        self.ipv4_fragmented_offset = fragment_flag_and_offset & 0x1FFF
+
         # Calculate the length (of the header?)
         ihl = version_ihl & 0xF
         self._iph_length = ihl * 4

snowsignal/udp_relay_transmit.py

@@ -141,7 +141,7 @@ def l3filter(self, packet: Packet) -> bool:
     def l4filter(self, packet: Packet) -> bool:
         """Tests to perform on Level4 of packet, i.e. UDP Protocol"""
         if packet.udp_dst_port != self.local_port:
-            logger.debug("Wrong UDP destination port: %i", packet.udp_dst_port)
+            logger.debug("Wrong UDP destination port: %i on packet %s", packet.udp_dst_port, packet)
             return False
 
         return True