feat (layer + test): fixed code health checks and Copilot's comments

AI-Assisted: yes (OpenAI Codex)

Author: pengsies

scapy/layers/hsrp.py

@@ -62,7 +62,7 @@ def _is_hsrpv2(pkt):
     tlvtype = orb(pkt[0:1])
     tlvlength = orb(pkt[1:2])
 
-    if tlvtype not in _HSRP_V2_TLV_TYPES:
+    if tlvtype == 0:
         return False
 
     if len(pkt) < 2 + tlvlength:
@@ -299,10 +299,10 @@ def post_build(self, p, pay):
 bind_layers(UDP, HSRP, dport=1985, sport=1985)
 
 DestIPField.bind_addr(UDP, "224.0.0.2", dport=1985)
-"""
-since port 1954 (UDP) would be shared by both hsrpv1 and hsprv2 (ipv4), 
-users building hsrpv2 (ipv4) packets should set IP(dst="224.0.0.102") explicitly to avoid using wrong multicast destination
-"""
+# UDP port 1985 is shared by HSRPv1 and HSRPv2 for IPv4
+# To avoid using the HSRPv1 multicast destination, explicitly set
+# IP(dst="224.0.0.102") when building HSRPv2 packets.
+# Otherwise, consider below for binding.
 # DestIPField.bind_addr(UDP, "224.0.0.102", dport=1985)
 
 if conf.ipv6_enabled:

test/scapy/layers/hsrp.uts

@@ -106,6 +106,17 @@ assert pkt[HSRPv2UnknownTLV].type == 99
 assert pkt[HSRPv2UnknownTLV].len == 4
 assert pkt[HSRPv2UnknownTLV].value == b"abcd"
 
+= HSRPv2 - Unknown first TLV UDP dispatch
+pkt = IP(raw(
+    IP(dst="224.0.0.102") /
+    UDP(dport=1985, sport=1985) /
+    HSRPv2UnknownTLV(type=99, value=b"abcd")
+))
+assert HSRPv2 in pkt and HSRPv2UnknownTLV in pkt and HSRP not in pkt
+assert pkt[HSRPv2UnknownTLV].type == 99
+assert pkt[HSRPv2UnknownTLV].len == 4
+assert pkt[HSRPv2UnknownTLV].value == b"abcd"
+
 = HSRPv2 - MD5 Auth TLV build & dissection
 digest = b"\x11" * 16
 pkt = HSRPv2(raw(