netbios: parse every address entry in a name query response

scapy/layers/netbios.py

@@ -198,6 +198,9 @@ class NBNS_ADD_ENTRY(Packet):
         IPField("NB_ADDRESS", "127.0.0.1")
     ]
 
+    def default_payload_class(self, payload):
+        return conf.padding_layer
+
 
 class NBNSQueryResponse(Packet):
     name = "NBNS query response"

test/scapy/layers/netbios.uts

@@ -40,6 +40,29 @@ assert z.RR_NAME == b'POTATO'
 assert z.ADDR_ENTRY[0].G == 0
 assert z.ADDR_ENTRY[0].NB_ADDRESS == "192.168.1.65"
 
+= NBNSQueryResponse - name registered on several addresses
+
+# RFC1002 sect 4.2.13: RDATA holds one {NB_FLAGS, NB_ADDRESS} pair per address
+# the name answers on, and RDLENGTH spans all of them.
+
+data = b'/S\x85\x80\x00\x00\x00\x01\x00\x00\x00\x00 FAEPFEEBFEEPCACACACACACACACACAAA\x00\x00 \x00\x01\x00\x03\xf4\x80\x00\x0c\x00\x00\xc0\xa8\x01A\x00\x00\xc0\xa8\x01B'
+z = NBNSHeader(data)
+assert z.RDLENGTH == 12
+assert len(z.ADDR_ENTRY) == 2
+assert [x.NB_ADDRESS for x in z.ADDR_ENTRY] == ["192.168.1.65", "192.168.1.66"]
+assert raw(z) == data
+
+z = NBNSHeader()/NBNSQueryResponse(RR_NAME="FRED", ADDR_ENTRY=[NBNS_ADD_ENTRY(NB_ADDRESS="192.168.0.13"), NBNS_ADD_ENTRY(NB_ADDRESS="192.168.0.14")])
+pkt = NBNSHeader(raw(z))
+assert pkt.RDLENGTH == 12
+assert [x.NB_ADDRESS for x in pkt.ADDR_ENTRY] == ["192.168.0.13", "192.168.0.14"]
+
+# RDLENGTH bounds the list: what follows the record is not an address entry
+
+pkt = NBNSHeader(data + b'\xde\xad\xbe\xef')
+assert len(pkt.ADDR_ENTRY) == 2
+assert raw(pkt) == data + b'\xde\xad\xbe\xef'
+
 = NBNSQueryResponse answers NBNSQueryRequest
 
 req = IP(ihl=5, len=78, proto=17, chksum=8562, src='172.19.0.7', dst='172.19.0.255')/UDP(sport=137, dport=137, len=58, chksum=62101)/NBNSHeader(NM_FLAGS=17, QDCOUNT=1)/NBNSQueryRequest(QUESTION_NAME=b'Loremipsumdolor', SUFFIX=17217)