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# $Id: cdp.py 23 2006-11-08 15:45:33Z dugsong $
"""Cisco Discovery Protocol."""
import struct
import dpkt
CDP_DEVID = 1 # string
CDP_ADDRESS = 2
CDP_PORTID = 3 # string
CDP_CAPABILITIES = 4 # 32-bit bitmask
CDP_VERSION = 5 # string
CDP_PLATFORM = 6 # string
CDP_IPPREFIX = 7
CDP_VTP_MGMT_DOMAIN = 9 # string
CDP_NATIVE_VLAN = 10 # 16-bit integer
CDP_DUPLEX = 11 # 8-bit boolean
CDP_TRUST_BITMAP = 18 # 8-bit bitmask0x13
CDP_UNTRUST_COS = 19 # 8-bit port
CDP_SYSTEM_NAME = 20 # string
CDP_SYSTEM_OID = 21 # 10-byte binary string
CDP_MGMT_ADDRESS = 22 # 32-bit number of addrs, Addresses
CDP_LOCATION = 23 # string
class CDP(dpkt.Packet):
__hdr__ = (
('version', 'B', 2),
('ttl', 'B', 180),
('sum', 'H', 0)
)
class Address(dpkt.Packet):
# XXX - only handle NLPID/IP for now
__hdr__ = (
('ptype', 'B', 1), # protocol type (NLPID)
('plen', 'B', 1), # protocol length
('p', 'B', 0xcc), # IP
('alen', 'H', 4) # address length
)
def unpack(self, buf):
dpkt.Packet.unpack(self, buf)
self.data = self.data[:self.alen]
class TLV(dpkt.Packet):
__hdr__ = (
('type', 'H', 0),
('len', 'H', 4)
)
def unpack(self, buf):
dpkt.Packet.unpack(self, buf)
self.data = self.data[:self.len - 4]
if self.type == CDP_ADDRESS:
n = struct.unpack('>I', self.data[:4])[0]
buf = self.data[4:]
l = []
for i in range(n):
a = CDP.Address(buf)
l.append(a)
buf = buf[len(a):]
self.data = l
def __len__(self):
if self.type == CDP_ADDRESS:
n = 4 + sum(map(len, self.data))
else:
n = len(self.data)
return self.__hdr_len__ + n
def __str__(self):
self.len = len(self)
if self.type == CDP_ADDRESS:
s = struct.pack('>I', len(self.data)) + \
''.join(map(str, self.data))
else:
s = self.data
return self.pack_hdr() + s
def unpack(self, buf):
dpkt.Packet.unpack(self, buf)
buf = self.data
l = []
while buf:
tlv = self.TLV(buf)
l.append(tlv)
buf = buf[len(tlv):]
self.data = l
def __len__(self):
return self.__hdr_len__ + sum(map(len, self.data))
def __str__(self):
data = ''.join(map(str, self.data))
if not self.sum:
self.sum = dpkt.in_cksum(self.pack_hdr() + data)
return self.pack_hdr() + data
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