Ignore critical layers from filter() (#4755)

Author: gpotter2

scapy/config.py

@@ -294,6 +294,12 @@ def __repr__(self):
     def register(self, layer):
         # type: (Type[Packet]) -> None
         self.append(layer)
+
+        # Skip arch* modules
+        if layer.__module__.startswith("scapy.arch."):
+            return
+
+        # Register in module
         if layer.__module__ not in self.ldict:
             self.ldict[layer.__module__] = []
         self.ldict[layer.__module__].append(layer)

test/regression.uts

@@ -288,6 +288,9 @@ pkt = NetflowHeader()/NetflowHeaderV5()/NetflowRecordV5()
 conf.layers.filter([NetflowHeader, NetflowHeaderV5])
 assert NetflowRecordV5 not in NetflowHeader(bytes(pkt))
 
+# Conf.ifaces.reload() should still work (arch/* is exempt)
+conf.ifaces.reload()
+
 conf.layers.unfilter()
 assert NetflowRecordV5 in NetflowHeader(bytes(pkt))