packet lib: don't crash with corrupted lldp packet

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Tested-by: Benjamin Eggerstedt <benjamin.eggerstedt@gmail.com>

ryu/lib/packet/lldp.py

@@ -124,7 +124,7 @@ class lldp(packet_base.PacketBase):
                 self.tlvs[-1].tlv_type == LLDP_TLV_END)
 
     @classmethod
-    def parser(cls, buf):
+    def _parser(cls, buf):
         tlvs = []
 
         while buf:
@@ -144,6 +144,13 @@ class lldp(packet_base.PacketBase):
 
         return lldp_pkt, None, buf
 
+    @classmethod
+    def parser(cls, buf):
+        try:
+            return cls._parser(buf)
+        except:
+            return None, None, buf
+
     def serialize(self, payload, prev):
         data = bytearray()
         for tlv in self.tlvs:

ryu/tests/unit/packet/test_lldp.py

@@ -286,6 +286,10 @@ class TestLLDPOptionalTLV(unittest.TestCase):
         # End
         eq_(tlvs[16].tlv_type, lldp.LLDP_TLV_END)
 
+    def test_parse_corrupted(self):
+        buf = self.data
+        pkt = packet.Packet(buf[:128])
+
     def test_serialize(self):
         pkt = packet.Packet()