213 lines
9.8 KiB
Python
Executable File
213 lines
9.8 KiB
Python
Executable File
#!/usr/bin/env python3
|
|
|
|
# INCOMPLETE
|
|
|
|
# See RFC 2131, Figure 1 and Table 1 (section 2)
|
|
# Much thanks to https://github.com/igordcard/dhcplease for digging into dhcpcd
|
|
# source for the actual file structure (and providing inspiration).
|
|
|
|
import argparse
|
|
import collections
|
|
import os
|
|
import re
|
|
import struct
|
|
from io import BytesIO
|
|
|
|
## DEFINE SOME PRETTY STUFF ##
|
|
class color(object):
|
|
PURPLE = '\033[95m'
|
|
CYAN = '\033[96m'
|
|
DARKCYAN = '\033[36m'
|
|
BLUE = '\033[94m'
|
|
GREEN = '\033[92m'
|
|
YELLOW = '\033[93m'
|
|
RED = '\033[91m'
|
|
BOLD = '\033[1m'
|
|
UNDERLINE = '\033[4m'
|
|
END = '\033[0m'
|
|
|
|
class packetParser(object):
|
|
def __init__(self, data):
|
|
## Set the segment labels and struct formats
|
|
self.fmt = collections.OrderedDict()
|
|
# In the below, 'cnt' is how large (in octets) the field is.
|
|
# 'fmt' is a struct format string (https://docs.python.org/3/library/struct.html#format-characters)
|
|
# "op" through "hops" (incl.) may actually be '8B' instead of '8c'.
|
|
self.fmt['op'] = {'cnt': 8, 'fmt': '8c'} # this will always be \x02
|
|
self.fmt['htype'] = {'cnt': 8, 'fmt': '8c'} # this will always be \x01
|
|
self.fmt['hlen'] = {'cnt': 8, 'fmt': '8c'}
|
|
self.fmt['hops'] = {'cnt': 8, 'fmt': '8c'}
|
|
self.fmt['xid'] = {'cnt': 32, 'fmt': '8I'}
|
|
self.fmt['secs'] = {'cnt': 16, 'fmt': '8H'}
|
|
self.fmt['flags'] = {'cnt': 16, 'fmt': '8H'}
|
|
# "ciaddr" through "giaddr" (incl.) may actually be '4c' instead of '4B'.
|
|
self.fmt['ciaddr'] = {'cnt': 4, 'fmt': '4B'}
|
|
self.fmt['yiaddr'] = {'cnt': 4, 'fmt': '4B'}
|
|
self.fmt['siaddr'] = {'cnt': 4, 'fmt': '4B'}
|
|
self.fmt['giaddr'] = {'cnt': 4, 'fmt': '4B'}
|
|
# "chaddr" through "file" (incl.) may actually be <#>c instead of <#>B.
|
|
self.fmt['chaddr'] = {'cnt': 16, 'fmt': '16B'} # first 6 bytes used for MAC addr of client
|
|
self.fmt['sname'] = {'cnt': 64, 'fmt': '64B'} # server host name (via BOOTP)
|
|
self.fmt['file'] = {'cnt': 128, 'fmt': '128B'} # the boot filename (for BOOTP)
|
|
# OPTIONS - RFC 2132
|
|
# Starting at octet 320 (so, f.seek(319, 0)) to the end of the message are
|
|
# DHCP options. It's a variable-length field so it makes things tricky
|
|
# for us. But it's at *least* 312 octets long per the RFC?
|
|
# It probably starts with a magic.
|
|
#self.dhcp_opts = {'idx': 324, 'cnt': 4, 'fmt': '4c'}
|
|
#self.dhcp_opts = {'idx': 324, 'cnt': 4, 'fmt': None}
|
|
self.opts = {'magic': b'\x63\x82\x53\x63',
|
|
'struct': {'idx': 324, 'cnt': 4, 'fmt': '4B'},
|
|
'size': 0,
|
|
'bytes': b'\00'}
|
|
## Convert the data into a bytes object because struct.unpack() wants a stream
|
|
self.buf = BytesIO(data)
|
|
|
|
def getStd(self):
|
|
self.reconstructed_segments = collections.OrderedDict()
|
|
_idx = 0 # add to this with the 'cnt' value for each iteration.
|
|
for k in self.fmt.keys():
|
|
print('Segment: ' + k) # TODO: remove, this stuff goes in the printer
|
|
pkt = struct.Struct(self.fmt[k]['fmt'])
|
|
self.buf.seek(_idx, 0)
|
|
try:
|
|
self.reconstructed_segments[k] = pkt.unpack(self.buf.read(self.fmt[k]['cnt']))
|
|
except struct.error as e:
|
|
# Some DHCP implementations are... broken.
|
|
# I've noticed it mostly in Verizon Fi-OS gateways/WAPs/routers.
|
|
print('Warning({0}): {1}'.format(k, e))
|
|
self.buf.seek(_idx, 0)
|
|
_truesize = len(self.buf.read(self.fmt[k]['cnt']))
|
|
print('Length of bytes read: {0}'.format(_truesize))
|
|
# But sometimes it's... kind of fixable?
|
|
if k == 'file' and _truesize < self.fmt[k]['cnt']:
|
|
self.buf.seek(_idx, 0)
|
|
self.fmt[k] = {'cnt': _truesize, 'fmt': '{0}B'.format(_truesize)}
|
|
pkt = struct.Struct(self.fmt[k]['fmt'])
|
|
print('Struct format size automatically adjusted.')
|
|
try:
|
|
self.reconstructed_segments[k] = pkt.unpack(self.buf.read(self.fmt[k]['cnt']))
|
|
except struct.error as e2:
|
|
# yolo.
|
|
print('We still couldn\'t populate {0}; filling with a nullbyte.'.format(k))
|
|
print('Error (try #2): {0}'.format(e2))
|
|
print('We read {0} bytes.'.format(_truesize))
|
|
print('fmt: {0}'.format(self.fmt[k]['fmt']))
|
|
self.reconstructed_segments[k] = b'\00'
|
|
_idx += self.fmt[k]['cnt']
|
|
self.buf.seek(_idx, 0)
|
|
# Finally, check for opts. If they exist, populate.
|
|
_optbytes = len(self.buf.read())
|
|
if _optbytes >= 1:
|
|
self.opts['size'] = _optbytes
|
|
self.buf.seek(_idx, 0)
|
|
self.opts['bytes'] = self.buf.read() # read to the end
|
|
return()
|
|
|
|
def getOpts(self):
|
|
pass
|
|
|
|
def close(self):
|
|
self.buf.close()
|
|
|
|
def parseArgs():
|
|
args = argparse.ArgumentParser()
|
|
_deflease = '/var/lib/dhcpcd/'
|
|
args.add_argument('-l', '--lease',
|
|
metavar = '/path/to/lease/dir/or_file.lease',
|
|
default = _deflease,
|
|
dest = 'leasepath',
|
|
help = ('The path to the directory of lease files or specific lease file. ' +
|
|
'If a directory is provided, all lease files found within will be ' +
|
|
'parsed. Default: {0}{1}{2}').format(color.BOLD,
|
|
_deflease,
|
|
color.END))
|
|
args.add_argument('-n', '--no-color',
|
|
action = 'store_false',
|
|
dest = 'color',
|
|
help = ('If specified, suppress color formatting in output.'))
|
|
args.add_argument('-d', '--dump',
|
|
metavar = '/path/to/dumpdir',
|
|
default = False,
|
|
dest = 'dump',
|
|
help = ('If provided, dump the parsed leases to this directory (in ' +
|
|
'addition to printing). It will dump with the same filename ' +
|
|
'and overwrite any existing file with the same filename, so ' +
|
|
'do NOT use the same directory as your dhcpcd lease files! ' +
|
|
'({0}-l/--lease{1}). The directory will be created if it does ' +
|
|
'not exist').format(color.BOLD,
|
|
color.END))
|
|
args.add_argument('-p', '--pretty',
|
|
action = 'store_true',
|
|
dest = 'prettyprint',
|
|
help = ('If specified, include color formatting {0}in the dump ' +
|
|
'file(s){1}').format(color.BOLD, color.END))
|
|
return(args)
|
|
|
|
def getLeaseData(fpath):
|
|
if not os.path.isfile(fpath):
|
|
raise FileNotFoundError('{0} does not exist'.format(fpath))
|
|
with open(fpath, 'rb') as f:
|
|
_data = f.read()
|
|
return(_data)
|
|
|
|
def iterLease(args):
|
|
# If the lease path is a file, just operate on that.
|
|
# If it's a directory, iterate (recursively) through it.
|
|
leases = {}
|
|
if not os.path.lexists(args['leasepath']):
|
|
raise FileNotFoundError('{0} does not exist'.format(args['leasepath']))
|
|
if os.path.isfile(args['leasepath']):
|
|
_pp = packetParser(getLeaseData(args['leasepath']))
|
|
# TODO: convert the hex vals to their actual vals... maybe?
|
|
_keyname = re.sub('^(dhcpcd-)?(.*)\.lease$',
|
|
'\g<2>',
|
|
os.path.basename(args['leasepath']))
|
|
leases[_keyname] = leaseParse(_pp, args)
|
|
else:
|
|
# walk() instead of listdir() because whotf knows when some distro like
|
|
# *coughcoughUbuntucoughcough* will do some breaking change like creating
|
|
# subdirs based on iface name or something.
|
|
for _, _, files in os.walk(args['leasepath']):
|
|
if not files:
|
|
continue
|
|
files = [i for i in files if i.endswith('.lease')] # only get .lease files
|
|
for i in files:
|
|
_args = args.copy()
|
|
_fpath = os.path.join(args['leasepath'], i)
|
|
_keyname = re.sub('^(dhcpcd-)?(.*)\.lease$', '\g<2>', os.path.basename(_fpath))
|
|
_dupeid = 0
|
|
# JUST in case there are multiple levels of dirs in the future
|
|
# that have files of the sama name
|
|
while _keyname in leases.keys():
|
|
# TODO: convert the hex vals to their actual vals... maybe?
|
|
_keyname = re.sub('^$',
|
|
'\g<1>.{0}'.format(_dupeid),
|
|
_keyname)
|
|
_dupeid += 1
|
|
_pp = packetParser(getLeaseData(_fpath))
|
|
leases[_keyname] = leaseParse(_pp, _args, fname = _fpath)
|
|
return(leases)
|
|
|
|
def leaseParse(pp, args, fname = False):
|
|
# Essentially just a wrapper function.
|
|
# Debugging output...
|
|
if fname:
|
|
print(fname)
|
|
pp.getStd()
|
|
pp.getOpts()
|
|
if args['dump']:
|
|
pass # TODO: write to files, creating dump dir if needed, etc.
|
|
pp.close()
|
|
# do pretty-printing (color-coded segments, etc.) here
|
|
return(pp.reconstructed_segments)
|
|
|
|
if __name__ == '__main__':
|
|
args = vars(parseArgs().parse_args())
|
|
args['leasepath'] = os.path.abspath(os.path.expanduser(args['leasepath']))
|
|
if not os.path.lexists(args['leasepath']):
|
|
exit('{0} does not exist!'.format(args['leasepath']))
|
|
leases = iterLease(args)
|
|
# just print for now until we write the parser/prettyprinter
|
|
print(list(leases.keys()))
|