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# SECUREAUTH LABS. Copyright 2018 SecureAuth Corporation. All rights reserved. 

# 

# This software is provided under under a slightly modified version 

# of the Apache Software License. See the accompanying LICENSE file 

# for more information. 

# 

# Description: 

# Cisco Discovery Protocol packet codecs. 

# 

# Author: 

# Martin Candurra 

# martincad at corest.com 

 

from struct import unpack 

import socket 

 

from impacket.ImpactPacket import Header 

from impacket import LOG 

 

IP_ADDRESS_LENGTH = 4 

 

class CDPTypes: 

 

DeviceID_Type = 1 

Address_Type = 2 

PortID_Type = 3 

Capabilities_Type = 4 

SoftVersion_Type = 5 

Platform_Type = 6 

IPPrefix_Type = 7 

ProtocolHello_Type = 8 

MTU_Type = 17 

SystemName_Type = 20 

SystemObjectId_Type = 21 

SnmpLocation = 23 

 

class CDP(Header): 

 

Type = 0x2000 

OUI = 0x00000c 

 

def __init__(self, aBuffer = None): 

Header.__init__(self, 8) 

if aBuffer: 

self.load_header(aBuffer) 

self._elements = self._getElements(aBuffer) 

 

def _getElements(self, aBuffer): 

# Remove version (1 byte), TTL (1 byte), and checksum (2 bytes) 

buff = aBuffer[4:] 

l = [] 

while buff: 

elem = CDPElementFactory.create(buff) 

l.append( elem ) 

buff = buff[ elem.get_length() : ] 

return l 

 

def get_header_size(self): 

return 8 

 

def get_version(self): 

return self.get_byte(0) 

 

def get_ttl(self): 

return self.get_byte(1) 

 

def get_checksum(self): 

return self.get_word(2) 

 

def get_type(self): 

return self.get_word(4) 

 

def get_lenght(self): 

return self.get_word(6) 

 

def getElements(self): 

return self._elements 

 

 

def __str__(self): 

tmp_str = 'CDP Details:\n' 

for element in self._elements: 

tmp_str += "** Type:" + str(element.get_type()) + " " + str(element) + "\n" 

return tmp_str 

 

 

def get_byte(buffer, offset): 

return unpack("!B", buffer[offset:offset+1])[0] 

 

def get_word(buffer, offset): 

return unpack("!h", buffer[offset:offset+2])[0] 

 

def get_long(buffer, offset): 

return unpack("!I", buffer[offset:offset+4])[0] 

 

def get_bytes(buffer, offset, bytes): 

return buffer[offset:offset + bytes] 

 

def mac_to_string(mac_bytes): 

bytes = unpack('!BBBBBB', mac_bytes) 

s = '' 

for byte in bytes: 

s += '%02x:' % byte 

return s[0:-1] 

 

 

 

class CDPElement(Header): 

 

def __init__(self, aBuffer = None): 

Header.__init__(self, 8) 

if aBuffer: 

self._length = CDPElement.Get_length(aBuffer) 

self.load_header( aBuffer[:self._length] ) 

 

@classmethod 

def Get_length(cls, aBuffer): 

return unpack('!h', aBuffer[2:4])[0] 

 

def get_header_size(self): 

self._length 

 

def get_length(self): 

return self.get_word(2) 

 

def get_data(self): 

return self.get_bytes().tostring()[4:self.get_length()] 

 

def get_ip_address(self, offset = 0, ip = None): 

if not ip: 

ip = self.get_bytes().tostring()[offset : offset + IP_ADDRESS_LENGTH] 

return socket.inet_ntoa( ip ) 

 

class CDPDevice(CDPElement): 

Type = 1 

 

def get_type(self): 

return CDPDevice.Type 

 

def get_device_id(self): 

return CDPElement.get_data(self) 

 

def __str__(self): 

return "Device:" + self.get_device_id() 

 

class Address(CDPElement): 

Type = 2 

 

def __init__(self, aBuffer = None): 

CDPElement.__init__(self, aBuffer) 

if aBuffer: 

data = self.get_bytes().tostring()[8:] 

self._generateAddressDetails(data) 

 

def _generateAddressDetails(self, buff): 

self.address_details = [] 

while buff: 

address = AddressDetails.create(buff) 

self.address_details.append( address ) 

buff = buff[address.get_total_length():] 

 

def get_type(self): 

return Address.Type 

 

def get_number(self): 

return self.get_long(4) 

 

def get_address_details(self): 

return self.address_details 

 

def __str__(self): 

tmp_str = "Addresses:" 

for address_detail in self.address_details: 

tmp_str += "\n" + str(address_detail) 

return tmp_str 

 

class AddressDetails(): 

 

PROTOCOL_IP = 0xcc 

 

@classmethod 

def create(cls, buff): 

a = AddressDetails(buff) 

return a 

 

 

def __init__(self, aBuffer = None): 

if aBuffer: 

addr_length = unpack("!h", aBuffer[3:5])[0] 

self.total_length = addr_length + 5 

self.buffer = aBuffer[:self.total_length] 

 

def get_total_length(self): 

return self.total_length 

 

def get_protocol_type(self): 

return self.buffer[0:1] 

 

def get_protocol_length(self): 

return get_byte( self.buffer, 1) 

 

def get_protocol(self): 

return get_byte( self.buffer, 2) 

 

def get_address_length(self): 

return get_word( self.buffer, 3) 

 

def get_address(self): 

address = get_bytes( self.buffer, 5, self.get_address_length() ) 

if self.get_protocol()==AddressDetails.PROTOCOL_IP: 

return socket.inet_ntoa(address) 

else: 

LOG.error("Address not IP") 

return address 

 

def is_protocol_IP(self): 

return self.get_protocol()==AddressDetails.PROTOCOL_IP 

 

def __str__(self): 

return "Protocol Type:%r Protocol:%r Address Length:%r Address:%s" % (self.get_protocol_type(), self.get_protocol(), self.get_address_length(), self.get_address()) 

 

class Port(CDPElement): 

Type = 3 

 

def get_type(self): 

return Port.Type 

 

def get_port(self): 

return CDPElement.get_data(self) 

 

def __str__(self): 

return "Port:" + self.get_port() 

 

 

class Capabilities(CDPElement): 

Type = 4 

 

def __init__(self, aBuffer = None): 

CDPElement.__init__(self, aBuffer) 

self._capabilities_processed = False 

 

self._router = False 

self._transparent_bridge = False 

self._source_route_bridge = False 

self._switch = False 

self._host = False 

self._igmp_capable = False 

self._repeater = False 

self._init_capabilities() 

 

def get_type(self): 

return Capabilities.Type 

 

def get_capabilities(self): 

return CDPElement.get_data(self) 

 

def _init_capabilities(self): 

if self._capabilities_processed: 

return 

 

capabilities = unpack("!L", self.get_capabilities())[0] 

self._router = (capabilities & 0x1) > 0 

self._transparent_bridge = (capabilities & 0x02) > 0 

self._source_route_bridge = (capabilities & 0x04) > 0 

self._switch = (capabilities & 0x08) > 0 

self._host = (capabilities & 0x10) > 0 

self._igmp_capable = (capabilities & 0x20) > 0 

self._repeater = (capabilities & 0x40) > 0 

 

def is_router(self): 

return self._router 

 

def is_transparent_bridge(self): 

return self._transparent_bridge 

 

def is_source_route_bridge(self): 

return self._source_route_bridge 

 

def is_switch(self): 

return self._switch 

 

def is_host(self): 

return self.is_host 

 

def is_igmp_capable(self): 

return self._igmp_capable 

 

def is_repeater(self): 

return self._repeater 

 

 

def __str__(self): 

return "Capabilities:" + self.get_capabilities() 

 

 

class SoftVersion(CDPElement): 

Type = 5 

 

def get_type(self): 

return SoftVersion.Type 

 

def get_version(self): 

return CDPElement.get_data(self) 

 

def __str__(self): 

return "Version:" + self.get_version() 

 

 

class Platform(CDPElement): 

Type = 6 

 

def get_type(self): 

return Platform.Type 

 

def get_platform(self): 

return CDPElement.get_data(self) 

 

def __str__(self): 

return "Platform:%r" % self.get_platform() 

 

 

class IpPrefix(CDPElement): 

Type = 7 

 

def get_type(self): 

return IpPrefix .Type 

 

def get_ip_prefix(self): 

return CDPElement.get_ip_address(self, 4) 

 

def get_bits(self): 

return self.get_byte(8) 

 

def __str__(self): 

return "IP Prefix/Gateway: %r/%d" % (self.get_ip_prefix(), self.get_bits()) 

 

class ProtocolHello(CDPElement): 

Type = 8 

 

def get_type(self): 

return ProtocolHello.Type 

 

def get_master_ip(self): 

return self.get_ip_address(9) 

 

def get_version(self): 

return self.get_byte(17) 

 

def get_sub_version(self): 

return self.get_byte(18) 

 

def get_status(self): 

return self.get_byte(19) 

 

def get_cluster_command_mac(self): 

return self.get_bytes().tostring()[20:20+6] 

 

def get_switch_mac(self): 

return self.get_bytes().tostring()[28:28+6] 

 

def get_management_vlan(self): 

return self.get_word(36) 

 

def __str__(self): 

return "\n\n\nProcolHello: Master IP:%s version:%r subversion:%r status:%r Switch's Mac:%r Management VLAN:%r" \ 

% (self.get_master_ip(), self.get_version(), self.get_sub_version(), self.get_status(), mac_to_string(self.get_switch_mac()), self.get_management_vlan()) 

 

class VTPManagementDomain(CDPElement): 

Type = 9 

 

def get_type(self): 

return VTPManagementDomain.Type 

 

def get_domain(self): 

return CDPElement.get_data(self) 

 

 

class Duplex(CDPElement): 

Type = 0xb 

 

def get_type(self): 

return Duplex.Type 

 

def get_duplex(self): 

return CDPElement.get_data(self) 

 

def is_full_duplex(self): 

return self.get_duplex()==0x1 

 

class VLAN(CDPElement): 

Type = 0xa 

 

def get_type(self): 

return VLAN.Type 

 

def get_vlan_number(self): 

return CDPElement.get_data(self) 

 

 

 

class TrustBitmap(CDPElement): 

Type = 0x12 

 

def get_type(self): 

return TrustBitmap.Type 

 

def get_trust_bitmap(self): 

return self.get_data() 

 

def __str__(self): 

return "TrustBitmap Trust Bitmap:%r" % self.get_trust_bitmap() 

 

class UntrustedPortCoS(CDPElement): 

Type = 0x13 

 

def get_type(self): 

return UntrustedPortCoS.Type 

 

def get_port_CoS(self): 

return self.get_data() 

 

def __str__(self): 

return "UntrustedPortCoS port CoS %r" % self.get_port_CoS() 

 

class ManagementAddresses(Address): 

Type = 0x16 

 

def get_type(self): 

return ManagementAddresses.Type 

 

class MTU(CDPElement): 

Type = 0x11 

 

def get_type(self): 

return MTU.Type 

 

class SystemName(CDPElement): 

Type = 0x14 

 

def get_type(self): 

return SystemName.Type 

 

class SystemObjectId(CDPElement): 

Type = 0x15 

 

def get_type(self): 

return SystemObjectId.Type 

 

class SnmpLocation(CDPElement): 

Type = 0x17 

 

def get_type(self): 

return SnmpLocation.Type 

 

 

class DummyCdpElement(CDPElement): 

Type = 0x99 

 

def get_type(self): 

return DummyCdpElement.Type 

 

class CDPElementFactory(): 

 

elementTypeMap = { 

CDPDevice.Type : CDPDevice, 

Port.Type : Port, 

Capabilities.Type : Capabilities, 

Address.Type : Address, 

SoftVersion.Type : SoftVersion, 

Platform.Type : Platform, 

IpPrefix.Type : IpPrefix, 

ProtocolHello.Type : ProtocolHello, 

VTPManagementDomain.Type : VTPManagementDomain, 

VLAN.Type : VLAN, 

Duplex.Type : Duplex, 

TrustBitmap.Type : TrustBitmap, 

UntrustedPortCoS.Type : UntrustedPortCoS, 

ManagementAddresses.Type : ManagementAddresses, 

MTU.Type : MTU, 

SystemName.Type : SystemName, 

SystemObjectId.Type : SystemObjectId, 

SnmpLocation.Type : SnmpLocation 

} 

 

@classmethod 

def create(cls, aBuffer): 

# print "CDPElementFactory.create aBuffer:", repr(aBuffer) 

# print "CDPElementFactory.create sub_type:", repr(aBuffer[0:2]) 

_type = unpack("!h", aBuffer[0:2])[0] 

# print "CDPElementFactory.create _type:", _type 

try: 

class_type = cls.elementTypeMap[_type] 

except KeyError: 

class_type = DummyCdpElement 

#raise Exception("CDP Element type %s not implemented" % _type) 

return class_type( aBuffer )