Added RIPv2 authentication header

Author: Jochen Bartl

scapy/layers/rip.py

@@ -14,27 +14,61 @@
 class RIP(Packet):
     name = "RIP header"
     fields_desc = [
-        ByteEnumField("cmd",1,{1:"req",2:"resp",3:"traceOn",4:"traceOff",5:"sun",
-                               6:"trigReq",7:"trigResp",8:"trigAck",9:"updateReq",
-                               10:"updateResp",11:"updateAck"}),
-        ByteField("version",1),
-        ShortField("null",0),
+        ByteEnumField("cmd", 1, {1:"req", 2:"resp", 3:"traceOn", 4:"traceOff",
+                                 5:"sun", 6:"trigReq", 7:"trigResp", 8:"trigAck",
+                                 9:"updateReq", 10:"updateResp", 11:"updateAck"}),
+        ByteField("version", 1),
+        ShortField("null", 0),
         ]
 
-class RIPEntry(Packet):
+    def guess_payload_class(self, payload):
+        if payload[:2] == "\xff\xff":
+            return RIPAuth
+        else:
+            return Packet.guess_payload_class(self, payload)
+
+class RIPEntry(RIP):
     name = "RIP entry"
     fields_desc = [
-        ShortEnumField("AF",2,{2:"IP"}),
-        ShortField("RouteTag",0),
-        IPField("addr","0.0.0.0"),
-        IPField("mask","0.0.0.0"),
-        IPField("nextHop","0.0.0.0"),
-        IntEnumField("metric",1,{16:"Unreach"}),
+        ShortEnumField("AF", 2, {2:"IP"}),
+        ShortField("RouteTag", 0),
+        IPField("addr", "0.0.0.0"),
+        IPField("mask", "0.0.0.0"),
+        IPField("nextHop", "0.0.0.0"),
+        IntEnumField("metric", 1, {16:"Unreach"}),
+        ]
+
+class RIPAuth(Packet):
+    name = "RIP authentication"
+    fields_desc = [
+        ShortEnumField("AF", 0xffff, {0xffff:"Auth"}),
+        ShortEnumField("authtype", 2, {1:"md5authdata", 2:"simple", 3:"md5"}),
+        ConditionalField(StrFixedLenField("password", None, 16),
+                                        lambda pkt: pkt.authtype == 2),
+        ConditionalField(ShortField("digestoffset", 0),
+                                        lambda pkt: pkt.authtype == 3),
+        ConditionalField(ByteField("keyid", 0),
+                                        lambda pkt: pkt.authtype == 3),
+        ConditionalField(ByteField("authdatalen", 0),
+                                        lambda pkt: pkt.authtype == 3),
+        ConditionalField(IntField("seqnum", 0),
+                                        lambda pkt: pkt.authtype == 3),
+        ConditionalField(StrFixedLenField("zeropad", None, 8),
+                                        lambda pkt: pkt.authtype == 3),
+        ConditionalField(StrLenField("authdata", None,
+                                length_from=lambda pkt: pkt.md5datalen),
+                                        lambda pkt: pkt.authtype == 1)
         ]
-        
+
+    def pre_dissect(self, s):
+        if s[2:4] == "\x00\x01":
+            self.md5datalen = len(s) - 4
+
+        return s
 
 
 bind_layers( UDP,           RIP,           sport=520)
 bind_layers( UDP,           RIP,           dport=520)
 bind_layers( RIP,           RIPEntry,      )
 bind_layers( RIPEntry,      RIPEntry,      )
+bind_layers( RIPAuth,       RIPEntry,      )