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#! /usr/bin/env python
# scapy.contrib.description = Cisco Discovery Protocol
# scapy.contrib.status = loads
#############################################################################
## ##
## cdp.py --- Cisco Discovery Protocol (CDP) extension for Scapy ##
## ##
## Copyright (C) 2006 Nicolas Bareil <nicolas.bareil AT eads DOT net> ##
## Arnaud Ebalard <arnaud.ebalard AT eads DOT net> ##
## EADS/CRC security team ##
## ##
## This program is free software; you can redistribute it and/or modify it ##
## under the terms of the GNU General Public License version 2 as ##
## published by the Free Software Foundation; version 2. ##
## ##
## This program is distributed in the hope that it will be useful, but ##
## WITHOUT ANY WARRANTY; without even the implied warranty of ##
## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU ##
## General Public License for more details. ##
## ##
#############################################################################
from scapy.packet import *
from scapy.fields import *
from scapy.layers.inet6 import *
#####################################################################
# Helpers and constants
#####################################################################
# CDP TLV classes keyed by type
_cdp_tlv_cls = { 0x0001: "CDPMsgDeviceID",
0x0002: "CDPMsgAddr",
0x0003: "CDPMsgPortID",
0x0004: "CDPMsgCapabilities",
0x0005: "CDPMsgSoftwareVersion",
0x0006: "CDPMsgPlatform",
0x0007: "CDPMsgIPPrefix",
0x0008: "CDPMsgProtoHello",
0x0009: "CDPMsgVTPMgmtDomain", # CDPv2
0x000a: "CDPMsgNativeVLAN", # CDPv2
0x000b: "CDPMsgDuplex", #
# 0x000c: "CDPMsgGeneric",
# 0x000d: "CDPMsgGeneric",
0x000e: "CDPMsgVoIPVLANReply",
0x000f: "CDPMsgVoIPVLANQuery",
0x0010: "CDPMsgPower",
0x0011: "CDPMsgMTU",
# 0x0012: "CDPMsgTrustBitmap",
# 0x0013: "CDPMsgUntrustedPortCoS",
# 0x0014: "CDPMsgSystemName",
# 0x0015: "CDPMsgSystemOID",
0x0016: "CDPMsgMgmtAddr",
# 0x0017: "CDPMsgLocation",
0x0019: "CDPMsgUnknown19",
# 0x001a: "CDPPowerAvailable"
}
_cdp_tlv_types = { 0x0001: "Device ID",
0x0002: "Addresses",
0x0003: "Port ID",
0x0004: "Capabilities",
0x0005: "Software Version",
0x0006: "Platform",
0x0007: "IP Prefix",
0x0008: "Protocol Hello",
0x0009: "VTP Mangement Domain", # CDPv2
0x000a: "Native VLAN", # CDPv2
0x000b: "Duplex", #
0x000c: "CDP Unknown command (send us a pcap file)",
0x000d: "CDP Unknown command (send us a pcap file)",
0x000e: "VoIP VLAN Reply",
0x000f: "VoIP VLAN Query",
0x0010: "Power",
0x0011: "MTU",
0x0012: "Trust Bitmap",
0x0013: "Untrusted Port CoS",
0x0014: "System Name",
0x0015: "System OID",
0x0016: "Management Address",
0x0017: "Location",
0x0018: "CDP Unknown command (send us a pcap file)",
0x0019: "CDP Unknown command (send us a pcap file)",
0x001a: "Power Available"}
def _CDPGuessPayloadClass(p, **kargs):
cls = conf.raw_layer
if len(p) >= 2:
t = struct.unpack("!H", p[:2])[0]
clsname = _cdp_tlv_cls.get(t, "CDPMsgGeneric")
cls = globals()[clsname]
return cls(p, **kargs)
class CDPMsgGeneric(Packet):
name = "CDP Generic Message"
fields_desc = [ XShortEnumField("type", None, _cdp_tlv_types),
FieldLenField("len", None, "val", "!H"),
StrLenField("val", "", length_from=lambda x:x.len - 4) ]
def guess_payload_class(self, p):
return conf.padding_layer # _CDPGuessPayloadClass
class CDPMsgDeviceID(CDPMsgGeneric):
name = "Device ID"
type = 0x0001
_cdp_addr_record_ptype = {0x01: "NLPID", 0x02: "802.2"}
_cdp_addrrecord_proto_ip = "\xcc"
_cdp_addrrecord_proto_ipv6 = "\xaa\xaa\x03\x00\x00\x00\x86\xdd"
class CDPAddrRecord(Packet):
name = "CDP Address"
fields_desc = [ ByteEnumField("ptype", 0x01, _cdp_addr_record_ptype),
FieldLenField("plen", None, "proto", "B"),
StrLenField("proto", None, length_from=lambda x:x.plen),
FieldLenField("addrlen", None, length_of=lambda x:x.addr),
StrLenField("addr", None, length_from=lambda x:x.addrlen)]
def guess_payload_class(self, p):
return conf.padding_layer
class CDPAddrRecordIPv4(CDPAddrRecord):
name = "CDP Address IPv4"
fields_desc = [ ByteEnumField("ptype", 0x01, _cdp_addr_record_ptype),
FieldLenField("plen", 1, "proto", "B"),
StrLenField("proto", _cdp_addrrecord_proto_ip, length_from=lambda x:x.plen),
ShortField("addrlen", 4),
IPField("addr", "0.0.0.0")]
class CDPAddrRecordIPv6(CDPAddrRecord):
name = "CDP Address IPv6"
fields_desc = [ ByteEnumField("ptype", 0x02, _cdp_addr_record_ptype),
FieldLenField("plen", 8, "proto", "B"),
StrLenField("proto", _cdp_addrrecord_proto_ipv6, length_from=lambda x:x.plen),
ShortField("addrlen", 16),
IP6Field("addr", "::1")]
def _CDPGuessAddrRecord(p, **kargs):
cls = conf.raw_layer
if len(p) >= 2:
plen = struct.unpack("B", p[1])[0]
proto = ''.join(struct.unpack("s" * plen, p[2:plen + 2])[0:plen])
if proto == _cdp_addrrecord_proto_ip:
clsname = "CDPAddrRecordIPv4"
elif proto == _cdp_addrrecord_proto_ipv6:
clsname = "CDPAddrRecordIPv6"
else:
clsname = "CDPAddrRecord"
cls = globals()[clsname]
return cls(p, **kargs)
class CDPMsgAddr(CDPMsgGeneric):
name = "Addresses"
fields_desc = [ XShortEnumField("type", 0x0002, _cdp_tlv_types),
ShortField("len", None),
FieldLenField("naddr", None, "addr", "!I"),
PacketListField("addr", [], _CDPGuessAddrRecord, count_from=lambda x:x.naddr) ]
def post_build(self, pkt, pay):
if self.len is None:
l = 8 + len(self.addr) * 9
pkt = pkt[:2] + struct.pack("!H", l) + pkt[4:]
p = pkt + pay
return p
class CDPMsgPortID(CDPMsgGeneric):
name = "Port ID"
fields_desc = [ XShortEnumField("type", 0x0003, _cdp_tlv_types),
FieldLenField("len", None, "iface", "!H"),
StrLenField("iface", "Port 1", length_from=lambda x:x.len - 4) ]
_cdp_capabilities = [ "Router",
"TransparentBridge",
"SourceRouteBridge",
"Switch",
"Host",
"IGMPCapable",
"Repeater"] + ["Bit%d" % x for x in range(25,0,-1)]
class CDPMsgCapabilities(CDPMsgGeneric):
name = "Capabilities"
fields_desc = [ XShortEnumField("type", 0x0004, _cdp_tlv_types),
ShortField("len", 8),
FlagsField("cap", 0, 32, _cdp_capabilities) ]
class CDPMsgSoftwareVersion(CDPMsgGeneric):
name = "Software Version"
type = 0x0005
class CDPMsgPlatform(CDPMsgGeneric):
name = "Platform"
type = 0x0006
_cdp_duplex = { 0x00: "Half", 0x01: "Full" }
# ODR Routing
class CDPMsgIPPrefix(CDPMsgGeneric):
name = "IP Prefix"
type = 0x0007
fields_desc = [ XShortEnumField("type", 0x0007, _cdp_tlv_types),
ShortField("len", 8),
IPField("defaultgw", "192.168.0.1") ]
# TODO : Do me !!!!!! 0x0008
class CDPMsgProtoHello(CDPMsgGeneric):
name = "Protocol Hello"
type = 0x0008
class CDPMsgVTPMgmtDomain(CDPMsgGeneric):
name = "VTP Management Domain"
type = 0x0009
class CDPMsgNativeVLAN(CDPMsgGeneric):
name = "Native VLAN"
fields_desc = [ XShortEnumField("type", 0x000a, _cdp_tlv_types),
ShortField("len", 6),
ShortField("vlan", 1) ]
class CDPMsgDuplex(CDPMsgGeneric):
name = "Duplex"
fields_desc = [ XShortEnumField("type", 0x000b, _cdp_tlv_types),
ShortField("len", 5),
ByteEnumField("duplex", 0x00, _cdp_duplex) ]
class CDPMsgVoIPVLANReply(CDPMsgGeneric):
name = "VoIP VLAN Reply"
fields_desc = [ XShortEnumField("type", 0x000e, _cdp_tlv_types),
ShortField("len", 7),
ByteField("status?", 1),
ShortField("vlan", 1)]
# TODO : Do me !!! 0x000F
class CDPMsgVoIPVLANQuery(CDPMsgGeneric):
name = "VoIP VLAN Query"
type = 0x000f
# fields_desc = [XShortEnumField("type", 0x000f, _cdp_tlv_types),
# FieldLenField("len", None, "val", "!H") ]
class _CDPPowerField(ShortField):
def i2repr(self, pkt, x):
if x is None:
x = 0
return "%d mW" % x
class CDPMsgPower(CDPMsgGeneric):
name = "Power"
# Check if field length is fixed (2 bytes)
fields_desc = [ XShortEnumField("type", 0x0010, _cdp_tlv_types),
ShortField("len", 6),
_CDPPowerField("power", 1337)]
class CDPMsgMTU(CDPMsgGeneric):
name = "MTU"
# Check if field length is fixed (2 bytes)
fields_desc = [ XShortEnumField("type", 0x0011, _cdp_tlv_types),
ShortField("len", 6),
ShortField("mtu", 1500)]
class CDPMsgMgmtAddr(CDPMsgAddr):
name = "Management Address"
type = 0x0016
class CDPMsgUnknown19(CDPMsgGeneric):
name = "Unknown CDP Message"
type = 0x0019
class CDPMsg(CDPMsgGeneric):
name = "CDP "
fields_desc = [ XShortEnumField("type", None, _cdp_tlv_types),
FieldLenField("len", None, "val", "!H"),
StrLenField("val", "", length_from=lambda x:x.len - 4) ]
class _CDPChecksum:
def post_build(self, pkt, pay):
p = pkt + pay
if self.cksum is None:
cksum = checksum(p)
p = p[:2] + struct.pack("!H", cksum) + p[4:]
return p
class CDPv2_HDR(_CDPChecksum, CDPMsgGeneric):
name = "Cisco Discovery Protocol version 2"
fields_desc = [ ByteField("vers", 2),
ByteField("ttl", 180),
XShortField("cksum", None),
PacketListField("msg", [], _CDPGuessPayloadClass) ]
bind_layers(SNAP, CDPv2_HDR, {"code": 0x2000, "OUI": 0xC})
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