Teredo: Basic parsing of teredo IPv6 packet header

Author: tuxuser

xcloud/protocol/ipv6.py

@@ -0,0 +1,26 @@
+import dpkt
+
+class IPv6Packet:
+    def __init__(
+        self,
+        ipv6_base: dpkt.ip6.IP6
+    ) -> None:
+        self.ipv6_base = ipv6_base
+    
+    @property
+    def data(self) -> bytes:
+        return self.ipv6_base.data
+
+    def __repr__(self):
+        return (
+            f"IPv6Packet(V={self.ipv6_base.v}, SRC={self.ipv6_base.src}, DST={self.ipv6_base.dst}, PLEN={self.ipv6_base.plen} NEXT={self.ipv6_base.nxt} HLIM={self.ipv6_base.hlim}) DATA={self.data}"
+        )
+
+    @classmethod
+    def parse(cls, data: bytes):
+        ipv6_base = dpkt.ip6.IP6(data)
+        if ipv6_base.v != 6:
+            raise ValueError(
+                f'Invalid IP version: Not 6'
+            )
+        return cls(ipv6_base)

xcloud/protocol/teredo.py

@@ -0,0 +1,31 @@
+import os
+from dataclasses import dataclass, field
+from struct import pack, unpack, unpack_from
+from typing import Any, List, Optional, Tuple, Union
+
+from . import ipv6
+
+TEREDO_PORT = 3544
+TEREDO_HEADER_LENGTH = 22
+
+class TeredoPacket:
+    def __init__(
+        self,
+        ipv6_base: ipv6.IPv6Packet
+    ) -> None:
+        self.ipv6 = ipv6_base
+
+    def __repr__(self) -> str:
+        return (
+            f"TeredoPacket(IPv6={self.ipv6})"
+        )
+
+    @classmethod
+    def parse(cls, data: bytes):
+        if len(data) < TEREDO_HEADER_LENGTH:
+            raise ValueError(
+                f"Teredo packet length is less than {TEREDO_HEADER_LENGTH} bytes"
+            )
+        base = ipv6.IPv6Packet.parse(data)
+        return cls(base)
+        

xcloud/scripts/pcap_reader.py

@@ -9,7 +9,7 @@
 from aioice import stun
 from construct.lib import containers
 
-from ..protocol import packets
+from ..protocol import packets, teredo
 
 
 logging.basicConfig(level=logging.DEBUG)
@@ -27,9 +27,13 @@ def print_rtp(rtp: rtp.RtpPacket) -> None:
 
     print(f'RTP: {payload_name.name} {rtp}')
 
+def print_teredo(teredo: teredo.TeredoPacket) -> None:
+    print(f'TEREDO: {teredo}')
+
 PACKET_TYPES = [
     (stun.parse_message, print_stun),
-    (rtp.RtpPacket.parse, print_rtp)
+    (rtp.RtpPacket.parse, print_rtp),
+    (teredo.TeredoPacket.parse, print_teredo)
 ]
 
 def packet_filter(filepath):
@@ -56,6 +60,7 @@ def parse_file(pcap_filepath: str) -> None:
                 instance = cls(packet)
                 print_func(instance)
             except:
+                #LOG.exception('Failed to parse')
                 pass