def decipher(self, key=16*'\0', dir=0):
# key: K_NAS_enc
# cnt: NAS uplink or downlink counter
# dir: direction (uplink / downlink)
# using self.EEA
#
# if no deciphering to apply
if self.SH() not in (2, 3) \
or self.EEA not in (None, EEA1, EEA2, EEA3):
return
if not hasattr(self, '_pay') \
or (not isinstance(self[-1], Str) and self[-1].CallName != '_enc'):
log(ERR, 'Layer3NAS - decipher: not ready for deciphering')
return
#
if self.EEA is None:
# null ciphering EEA0
dec = str(self[-1])
else:
dec = self.EEA(key, self.SN(), 0, dir, str(self[-1]))
#
# get the complete packet buffer
buf = str(self[:4]) + dec
# reinsert NAS payload IEs
self.remove(self[-1])
self.extend(self._pay)
# remap the complete deciphered buffer to the NAS layer
Layer3.map(self, buf)
self._map_eps_id()
def interpret_IE(self, field, cn):
# interpret field as cn
# cn is looked up in L3Mobile_IE, L3GSM_IE or L3GSM_RR libs
if self.dbg >= DBG:
log(DBG, 'Layer3 - interpret IE: %s' % cn)
# check if direct field, or (T)LV-like field
if hasattr(field, 'V'):
# bypass IE interpretation in case of LV or TLV with null length
if hasattr(field, 'L') and field.L() == 0:
return
f_val = field.V
else:
f_val = field
# replace the raw field value by pointing to the retrieved IE
buf = str(f_val)
ie = IE_lookup[cn]()
try:
ie.map(buf)
except:
if self.dbg >= WNG:
log(WNG, 'Layer3 - IE mapping failed for %s' % ie.__class__)
else:
# only update the field if we got correct length data for the IE
if str(ie) == buf:
#if len(ie) == len(buf):
f_val < None
f_val > ie
# and go for human representation...
f_val.Repr = 'hum'
def test_dict():
e = 0
for pd in L3Call:
for msg in L3Call[pd]:
error = ''
cl = L3Call[pd][msg]
if not issubclass(cl, Layer3):
log(WNG, 'message %s not subclass of Layer3' % repr(cl))
else:
try:
m = cl(with_options=True)
except:
error = '__init__(with_options=True)'
else:
try:
buf = str(m)
except:
error = '__str__()'
else:
try:
m2 = cl(with_options=False)
m2.parse(buf)
except:
error = 'parse()'
else:
if str(m2) != buf:
error = '__str__() result discrepancy ' + \
' with parse()d buffer'
if error:
log(ERR, 'message %s test returns error: %s' \
% (repr(cl), error))
e += 1
return e
def test_dict():
e = 0
for pd in L3Call:
for msg in L3Call[pd]:
error = ''
cl = L3Call[pd][msg]
if not issubclass(cl, Layer3):
log(WNG, 'message %s not subclass of Layer3' % repr(cl))
else:
try:
m = cl(with_options=True)
except:
error = '__init__(with_options=True)'
else:
try:
buf = str(m)
except:
error = '__str__()'
else:
try:
m2 = cl(with_options=False)
m2.parse(buf)
except:
error = 'parse()'
else:
if str(m2) != buf:
error = '__str__() result discrepancy ' + \
' with parse()d buffer'
if error:
log(ERR, 'message %s test returns error: %s' \
% (repr(cl), error))
e += 1
return e
def _build_path(self, csn1iter):
# WNG : there is probably an issue as the ._offset attribute
# is not changed during the several recursive calls...
#
cnt=0
# recursive loading of CSN.1 fields, following the path of conditions
for f in csn1iter:
if self.dbg >= DBG:
log(DBG, '(_build_path - %s) iterating over: %s' \
% (self.__class__, repr(f)))
if isinstance(f, CSN1FIELDS):
#print('<<<<<<<<<<<<<<<<<<<<<< %s' % f.CallName)
self._append_csn1_field(f)
elif isinstance(f, tuple):
self._build_path(f)
#
elif isinstance(f, dict):
# in case there is no more conditions privided
if not self._cur_path:
self._build_auto(csn1iter[cnt:])
return
# this is the case were we need to consume the _cur_path
# and append the values as of the provided conditions
#
self._build_from_dict(f)
#
cnt += 1
def interpret_IE(self, field, cn):
# interpret field as cn
# cn is looked up in L3Mobile_IE, L3GSM_IE or L3GSM_RR libs
if self.dbg >= DBG:
log(DBG, 'Layer3 - interpret IE: %s' % cn)
# check if direct field, or (T)LV-like field
if hasattr(field, 'V'):
# bypass IE interpretation in case of LV or TLV with null length
if hasattr(field, 'L') and field.L() == 0:
return
f_val = field.V
else:
f_val = field
# replace the raw field value by pointing to the retrieved IE
buf = str(f_val)
ie = IE_lookup[cn]()
try:
ie.map(buf)
except:
if self.dbg >= WNG:
log(WNG, 'Layer3 - IE mapping failed for %s' % ie.__class__)
else:
# only update the field if we got correct length data for the IE
if str(ie) == buf:
#if len(ie) == len(buf):
f_val < None
f_val > ie
# and go for human representation...
f_val.Repr = 'hum'
def map(self, s=''):
if not s:
return
# check the security header
s0 = ord(s[0])
sh, pd = s0>>4, s0&0xF
# ESM, or EMM with no security header
if pd == 2 or sh in (0, 12):
self.__init__(with_security=False)
Layer3.map(self, s)
self._map_eps_id()
# EMM with security header
elif pd == 7 and sh in (1, 2, 3, 4):
self.ins_sec_hdr()
# if no ciphering applied
if sh in (1, 3):
#if sh in (1, 3) or self.EEA not in (EEA1, EEA2, EEA3):
# if no payload is already there, just add a ciphered-like one
if len(self.elementList) == 4:
self << Str('_enc')
# map directly the buffer onto the NAS payload
Layer3.map(self, s)
self._map_eps_id()
else:
# keep track of all IE of the original packet
self._pay = self[4:]
# replace them with a dummy string
for ie in self._pay:
self.remove(ie)
self << Str('_enc')
Layer3.map(self, s)
else:
log(ERR, '[ERR] invalid Security Header value %i' % sh)
def _cond_error(self, condset):
#if self.dbg >= ERR:
# log(ERR, '(CSN1._get_cond - %s) undefined CSN1 condition set: %s' \
# % (condset, self.__class__))
log(ERR, '(CSN1._get_cond - %s) undefined CSN1 condition set: %s' \
% (condset, self.__class__))
if self.safe:
assert()
def _select_tag(self, s='\0', taglist=[]):
# check for 4 bits and 8 bits tags
t4, t8 = ord(s[0])>>4, ord(s[0])
if self.dbg >= DBG:
log(DBG, '(Layer3 - %s) t4, t8: %s, %s\ntaglist: %s' \
% (self.CallName, t4, t8, taglist))
#
# try another way:
# prefer the tag which is 1st in the taglist, whatever tag length
for t in taglist:
if t in (t4, t8):
return t
return None
def _select_tag(self, s='\0', taglist=[]):
# check for 4 bits and 8 bits tags
t4, t8 = ord(s[0]) >> 4, ord(s[0])
if self.dbg >= DBG:
log(DBG, '(Layer3 - %s) t4, t8: %s, %s\ntaglist: %s' \
% (self.CallName, t4, t8, taglist))
#
# try another way:
# prefer the tag which is 1st in the taglist, whatever tag length
for t in taglist:
if t in (t4, t8):
return t
return None
def _append_path(self, path):
if self.dbg >= DBG:
log(DBG, '(build - %s) going path: %s' \
% (self.__class__, repr(path)))
cond = ''
for c in path:
# if LH, get the correct value with self._offset
if c in 'LH':
L = self.L[self._offset%8]
self.append(Bit('%s' % self.cond_name, \
Pt={'L':L, 'H':(1, 0)[L]}[c] , BitLen=1))
elif c in '01':
self.append(Bit('%s' % self.pad_name, Pt=int(c, 2), BitLen=1))
else:
self._cond_error(path)
self._offset += 1
def _build_auto(self, csn1iter):
#print self.CallName
# recursive automatic loading of CSN.1 fields
for f in csn1iter:
if self.dbg >= DBG:
log(DBG, '(_build_auto - %s) iterating over: %s' \
% (self.__class__, repr(f)))
if isinstance(f, CSN1FIELDS):
self._append_csn1_field(f)
elif isinstance(f, tuple):
self._build_auto(f)
elif isinstance(f, dict):
# select the shortest path: BREAK, BREAK_LOOP,
# or the shortest value
values = f.values()
# easiest path is to get straight out of the dict
if BREAK in values or BREAK_LOOP in values:
for i in f.items():
if i[1] in (BREAK, BREAK_LOOP):
self._append_path(i[0])
break
# 2nd easiest path is to take a single CSN1FIELDS if exist
elif True in [isinstance(i, CSN1FIELDS) for i in values]:
for i in f.items():
# "au petit bonheur la chance"
if isinstance(i[1], CSN1FIELDS):
self._append_path(i[0])
self._append_csn1_field(i[1])
break
# 3rd easiest path is to take the shortest tuple available
elif True in [isinstance(i, tuple) for i in values]:
min_tuple = min(map(len, values))
for i in f.items():
if len(i[1]) == min_tuple:
# "au petit bonheur la chance" again
self._append_path(i[0])
self._build_auto(i[1])
break
# 4th easiest path is to enter the shortest dict available
elif True in [isinstance(i, dict) for i in values]:
min_dict = min(map(len, values))
for i in f.items():
if len(i[1]) == min_dict:
# "au petit bonheur la chance" once again
self._append_path(i[0])
self._build_auto(i[1])
break
def _select_tag_old_(self, s='\0', taglist=[]):
# check for 4 bits and 8 bits tags
t4, t8 = ord(s[0]) >> 4, ord(s[0])
if self.dbg >= DBG:
log(DBG, '(Layer3 - %s) t4, t8: %s, %s\ntaglist: %s' \
% (self.CallName, t4, t8, taglist))
#
# handle 4 bits tag in priority
# guessing from 3GPP spec:
# 4 bits and 8 bits tags should never clash...
# actually, this is not always the case
# e.g. for tag 4 (BearerCap) and 64 (SuppCodecs)
# TODO: this is actually a real issue,
# e.g. with GSM RR ASSIGNMENT_COMMAND
if t4 in taglist:
return t4
elif t8 in taglist:
return t8
return None
def __get_opts(self):
found_opt, opt_ie = False, []
# we have at least 3 mandatory fields (L3 header: SI, PD, Type)
# and we should not have any IE left, except StrRR for GSM RR
if isinstance(self[-1], StrRR): ie_to_check = self[3:-1]
else: ie_to_check = self[3:]
#
for ie in ie_to_check:
if hasattr(ie, 'T') or isinstance(ie, (Type2, StrRR)):
found_opt = True
opt_ie.append(ie)
# make all optional fields not transparent (so all of them
# can be mapped, whatever Layer3.__init__() options given)
ie.Trans = False
elif found_opt and self.dbg >= ERR:
# we should not find mandatory IE after optional
log(ERR, '(Layer3 - %s) mandatory IE found after ' \
'optional ones' % self.CallName)
return opt_ie
def __get_opts(self):
found_opt, opt_ie = False, []
# we have at least 3 mandatory fields (L3 header: SI, PD, Type)
# and we should not have any IE left, except StrRR for GSM RR
if isinstance(self[-1], StrRR): ie_to_check = self[3:-1]
else: ie_to_check = self[3:]
#
for ie in ie_to_check:
if hasattr(ie, 'T') or isinstance(ie, (Type2, StrRR)):
found_opt = True
opt_ie.append(ie)
# make all optional fields not transparent (so all of them
# can be mapped, whatever Layer3.__init__() options given)
ie.Trans = False
elif found_opt and self.dbg >= ERR:
# we should not find mandatory IE after optional
log(ERR, '(Layer3 - %s) mandatory IE found after ' \
'optional ones' % self.CallName)
return opt_ie
def _select_tag_old_(self, s='\0', taglist=[]):
# check for 4 bits and 8 bits tags
t4, t8 = ord(s[0])>>4, ord(s[0])
if self.dbg >= DBG:
log(DBG, '(Layer3 - %s) t4, t8: %s, %s\ntaglist: %s' \
% (self.CallName, t4, t8, taglist))
#
# handle 4 bits tag in priority
# guessing from 3GPP spec:
# 4 bits and 8 bits tags should never clash...
# actually, this is not always the case
# e.g. for tag 4 (BearerCap) and 64 (SuppCodecs)
# TODO: this is actually a real issue,
# e.g. with GSM RR ASSIGNMENT_COMMAND
if t4 in taglist:
return t4
elif t8 in taglist:
return t8
return None
def map(self, string='', byte_offset=0):
# pop each member of the initial csn1List
# and see what we have
# 1) CSN1FIELD -> map it directly
# 2) dict -> conditions -> CSN1FIELD | dict | tuple
# 3) tuple -> CSN1FIELD | dict
# consume the string buffer bit per bit depending of the
# csn1List member poped
#
# as a CSN1 field does not always start on a byte limit,
# we need to keep track of the byte offset,
# for solving padding (L | H) adequately
#
# in case CSN1 list is empty
if len(self.csn1List) == 0:
return
# initialize the string buffer to be mapped
self.BUF, self._buflen = shtr(string), len(string)*8
self._consumed, self._offset, self._map_exit = 0, byte_offset, False
self.elementList = []
#
# MAIN loop
# go over the string, bit per bit
index = 0
while (self._consumed + self._offset) < self._buflen:
if self._map_exit:
break
# get csn1 fields 1 by 1
self._eval_csn1(self.csn1List[index])
index += 1
# when csn1List is empty, finish with padding
if index >= len(self.csn1List):
break
#
# TODO: the padding should only be done when instructed so in CSN1
remaining = self._buflen - (self._consumed + self._offset)
if remaining:
if self.dbg >= DBG:
log(DBG, '(CSN1._eval_csn1_dict) bits are remaining unmapped')
# clean temporary data
del self.BUF, self._buflen, self._consumed, \
self._offset, self._map_exit
def _WtoF(self, index, fmt):
# J := GREATEST_POWER_OF_2_LESSER_OR_EQUAL_TO(INDEX);
J = [j for j in [1, 2, 4, 8, 16, 32, 64, 128] if j <= index].pop()
N = getattr(self, "W_%i" % index)()
#
while index > 1:
if (2 * index) < (3 * J):
index = index - (J / 2)
# for range 1024, we have to take W(PARENT)
par = self._get_W_parent(index, fmt)
N = ((N + par + (fmt / J) - 2) % (((fmt * 2) / J) - 1)) + 1
else:
index = index - J
# for range 1024, we have to take W(PARENT)
par = self._get_W_parent(index, fmt)
N = (N + par + ((fmt * 2) / J) - 2) % (((fmt * 2) / J) - 1) + 1
J = J / 2
if self.dbg >= DBG:
log(DBG, "L3GSM_IE ARFCN WtoF - N: %i" % N)
return N
def _append_from_dict(self, from_dict, condlen):
# xtra verbose debugging
if self.dbg > DBG:
if type(from_dict) is tuple: obj = list(from_dict)
elif hasattr(from_dict, 'CallName'): obj = from_dict.CallName
else: obj = from_dict
log(DBG, '(CSN1._eval_csn1_dict) selected from_dict: %s' % obj)
# if condition lead to None: padding
if from_dict == BREAK:
self._append_map_csn1_field(Bit('%s' % self.pad_name, BitLen=condlen))
# if condition lead to breaking a loop
# for crappy CSN1 syntax like {1 expr}**0
elif from_dict == BREAK_LOOP:
self._append_map_csn1_field(Bit('%s' % self.pad_name, BitLen=condlen))
self._loop = False
# if condition lead to something:
else:
self._append_map_csn1_field(Bit('%s' % self.cond_name, BitLen=condlen))
# recurse to the main csn1 eval method applied to object from dict
self._eval_csn1(from_dict)
def _append_csn1_field(self, field):
if isinstance(field, LHFlag):
#print self._offset
if self.L[self._offset%8] == 1:
field.LHdict = iad({1:'L', 0:'H'})
if isinstance(field, CSN1):
# initialize the field without building it any specific way
f = field.__class__(False, None)
# and then call build() in order to pass the _offset attribute
path = self._cur_path if hasattr(self, '_cur_path') else None
f.build(f.csn1List, self._offset, path)
#
if self.dbg >= DBG:
log(DBG, '(_append_csn1_field) field %s with path %s'\
% (f.CallName, path))
self.append(f)
self._offset += f.bit_len()
#
else:
self.append(field)
self._offset += field.bit_len()
def get_deciphered(self, key=16*'\0', dir=0):
#Â this is to get the deciphered stream of a NAS EMM message
#
# no NAS security
if self.SH() == 0 and not hasattr(self, 'MAC'):
return str(self)
#
# NAS security, only integrity protection
elif self.SH() in (1, 3) and hasattr(self, 'MAC'):
return str(self[4:])
#
# NAS security, ciphered
elif self.SH() in (2, 4) and hasattr(self, 'MAC'):
if self.EEA is None:
# null ciphering EEA0
return str(self[4:])
elif self[-1].CallName == '_enc':
return self.EEA(key, self.SN(), 0, dir, str(self[-1]))
#
log(ERR, 'Layer3NAS - get_deciphered: could not retrieve NAS payload')
return ''
def _get_ccch(self, string=''):
# this is to decode reliably GSM broadcast
#
if len(string) < 3:
self << RawLayer()
self[-1].map(string)
return
#
l = LengthRR()
l.map(string[0:1])
h = Header()
h.map(string[1:3])
# should check length (l) coherence here (including with M bit)
# ...
# check for non-RR protocol, or truncated string
#print('L1CTL decoding ; h.PD %s, string length %s' % (h.PD(), len(string)))
if h.PD() != 6 or len(string) < 22:
self << l
self | RawL3()
self[-1].map(string[1:])
return
#
# if we have the complete RR decoder
if h.Type() in L3Call[6].keys():
rr = L3Call[6][h.Type()]()
try:
rr.map(string)
self << rr
return
except:
pass
#
# otherwise, it's the generic RR decoder
# what is not very smart... however !
if self.dbg >= DBG:
log(DBG, '(L1CTL - L3GSM_RR) message parsing failed with:\n%s' \
% hexlify(string))
self << RR_gene()
self[-1].map(string)
def _get_ccch(self, string=''):
# this is to decode reliably GSM broadcast
#
if len(string) < 3:
self << RawLayer()
self[-1].map(string)
return
#
l = LengthRR()
l.map(string[0:1])
h = Header()
h.map(string[1:3])
# should check length (l) coherence here (including with M bit)
# ...
# check for non-RR protocol, or truncated string
#print('L1CTL decoding ; h.PD %s, string length %s' % (h.PD(), len(string)))
if h.PD() != 6 or len(string) < 22:
self << l
self | RawL3()
self[-1].map(string[1:])
return
#
# if we have the complete RR decoder
if h.Type() in L3Call[6].keys():
rr = L3Call[6][h.Type()]()
try:
rr.map(string)
self << rr
return
except:
pass
#
# otherwise, it's the generic RR decoder
# what is not very smart... however !
if self.dbg >= DBG:
log(DBG, '(L1CTL - L3GSM_RR) message parsing failed with:\n%s' \
% hexlify(string))
self << RR_gene()
self[-1].map(string)
def __map_opt(self, tag, string, opt_ie):
# retrieve 1st optional IE for the given tag: in opt
opt = None
for ie in opt_ie:
if ie[0]() == tag:
opt = ie
break
# remove it from the opt_ie list that will be further processed
# python's "remove()" remove the 1st iteration of an element in a list
if not opt:
log(ERR, '(Layer3 - %s) no remaining optional field for tag %i' \
% (self.CallName, tag))
return '', opt_ie
opt_ie.remove(opt)
# force it to be not transparent, map it and truncate the string
opt.Trans = False
opt.map(string)
if self.dbg >= DBG:
log(DBG, '(Layer3 - %s) mapping %s on %s' \
% (self.__class__, hexlify(string), opt.CallName))
string = string[opt.map_len():]
return string, opt_ie
def __map_opt(self, tag, string, opt_ie):
# retrieve 1st optional IE for the given tag: in opt
opt = None
for ie in opt_ie:
if ie[0]() == tag:
opt = ie
break
# remove it from the opt_ie list that will be further processed
# python's "remove()" remove the 1st iteration of an element in a list
if not opt:
log(ERR, '(Layer3 - %s) no remaining optional field for tag %i' \
% (self.CallName, tag))
return '', opt_ie
opt_ie.remove(opt)
# force it to be not transparent, map it and truncate the string
opt.Trans = False
opt.map(string)
if self.dbg >= DBG:
log(DBG, '(Layer3 - %s) mapping %s on %s' \
% (self.__class__, hexlify(string), opt.CallName))
string = string[opt.map_len():]
return string, opt_ie
def _decode_range(self, fmt):
# go over all W fields and apply the computation algorithm
# as of 10.5.2.3.13.3
# some discrepancies exist between the 4 ranges:
# 1) computing the next F
# 2) initial and number of F
if fmt == 1024:
if self.F0():
ar_list = [0]
else:
ar_list = []
ind_max = 17
app = lambda N: ar_list.append(N)
elif fmt in (128, 256, 512):
ar_list = [self.orig_arfcn()]
if fmt == 128:
ind_max = 29
elif fmt == 256:
ind_max = 22
elif fmt == 512:
ind_max = 18
app = lambda N: ar_list.append((ar_list[0] + N) % 1024)
#
# loop over all non-null W values to compute corresponding F
for ind in range(1, ind_max):
if getattr(self, "W_%i" % ind)():
app(self._WtoF(ind, fmt))
#
if self.dbg >= DBG:
log(
DBG,
"L3GSM_IE ARFCN WtoF - index %i; W %i; F %i"
% (ind, getattr(self, "W_%i" % ind)(), ar_list[-1]),
)
else:
break
#
return sorted(ar_list)
def _build_from_dict(self, d):
# TODO: if BREAK_LOOP in the dict,
# we should iterate as much time as provided in the path list
#
conds = d.keys()
#vals = d.values()
#
# select the value corresponding to the condition in _cur_path
if self.dbg >= DBG:
log(DBG, '(_build_path) _cur_path to process: %s' % self._cur_path)
cond_from_path = self._cur_path.pop(0)
if cond_from_path not in conds:
raise(Exception('path %s does not correspond to any condition'\
' for building %s' % (cond_from_path, self.__class__)))
#
self._append_path(cond_from_path)
field = d[cond_from_path]
if field not in (BREAK, BREAK_LOOP):
if isinstance(field, CSN1FIELDS):
#print('<<<<<<<<<<<<<<<<<<<<<< %s' % field.CallName)
self._append_csn1_field(field)
else:
# for tuple or dict, go the recursive way
self._build_path(field)
def parse(self, s='', phy_included=True, fcs_included=True):
#
if self.PHY_INCL:
# insert PHY() preamble and map the buffer to it
if len(self.layerList) > 0 :
self.layerList = []
self << PHY()
self[0].map(s)
#
# verify preamble
if self[0].Preamble() != '\0\0\0\0' and self.dbg >= ERR:
log(ERR, 'bad 802.15.4 preamble in PHY')
if len(s) != self.PHY.Length()+6 and self.dbg >= ERR:
log(ERR, 'buffer longer than indicated in PHY header')
# truncate string buffer
s=s[6:6+self.PHY.Length()]
else:
if len(self.layerList) > 0:
self.layerList = []
#
# standard 802.15.4 MAC header
# insert MAC and map the buffer to it
self << MAC()
self[-1].map(s)
s = s[len(self[-1]):]
# insert DATA layer
if self.FCS_INCL:
if len(s) > 2:
self << Data()
self[-1].map(s[:-2])
if len(s) >= 2:
self >> FCS()
self[-1].map(s[-2:])
# verify CRC
crc = self.FCS.FCS()
self.FCS.FCS < None
if self.FCS.FCS() != crc and self.dbg >= ERR:
log(ERR, 'bad 802.15.4 CRC16 in MAC suffix')
# refill with the original value
self.FCS.FCS < crc
elif self.dbg >= ERR:
log(ERR, 'buffer not long enough for FCS')
elif len(s) > 0:
self << Data()
self[-1].map(s)
def _append_map_csn1_field(self, csn1f):
# ensure there is still enough buffer to map on new fields
if hasattr(csn1f, 'bit_len') \
and csn1f.bit_len() > (self._buflen - (self._consumed+self._offset)):
if self.dbg >= WNG:
log(WNG, '(CSN1.map - %s) buffer not long enough for field: ' \
'%s from csn1List' % (self.__class__, csn1f.CallName))
self._map_exit = True
return
# append the field to the layer
if self.dbg >= DBG:
log(DBG, '(CSN1._append_map_csn1_field) appending csn1 field: %s' \
% csn1f.CallName)
#
# map the BUF on the element: this solves its bit length
# moreover, we transmit the byte offset, for solving correctly L|H flags
if type(csn1f) == type and issubclass(csn1f, CSN1):
self.append(csn1f().clone())
else:
self.append(csn1f)
#
if isinstance(self[-1], CSN1):
self[-1].map(self.BUF, (self._consumed+self._offset)%8)
bitlen = self[-1].bit_len()
else:
self[-1].map(self.BUF)
bitlen = self[-1].bit_len()
# check if LHFlag to possibly update its LH dictionnary
if isinstance(self[-1], LHFlag):
l = self.L[(self._consumed+self._offset)%8]
h = (1, 0)[l]
self[-1].LHdict = iad({l:'L', h:'H'})
#
# update global BUFFER and consumed bit length
self.BUF = self.BUF << bitlen
self._consumed += bitlen
def __map_opts(self, string=''):
# retrieve all optional IE from the Layer3 into opt_ie list
opt_ie = self.__get_opts()
taglist = [ie[0]() for ie in opt_ie if not isinstance(ie, StrRR)]
if self.dbg >= DBG:
log(DBG, '(Layer3 - %s) opt_ie: %s' % (self.CallName, opt_ie))
# go over the string and map to optional IE found
while len(string) > 0:
# check each iteration for the right tag
t = self._select_tag(string[0], taglist)
if t:
string, opt_ie = self.__map_opt(t, string, opt_ie)
taglist.remove(t)
#
else:
if self.dbg >= ERR:
log(WNG, '(Layer3 - %s) unknown optional IE' \
% self.CallName)
# could try to map it as a TLV, or TLVextended, or TV, or T...
# check the TS 24.007, section 11.2.4, for being amazed...
string2 = self.__map_unknown_opt(string)
if string2 == string:
break
string = string2
#
# optional IE that have not been mapped have to go "transparent"
if len(opt_ie) > 0:
[setattr(ie, 'Trans', True) for ie in opt_ie]
if self.dbg >= DBG:
log(DBG, '(Layer3 - %s) not all optional IE used\nremaining:' \
' %s' % (self.CallName, opt_ie))
# this should only happen when __map_unknown_opt() cannot
# consume remaining string.
if len(string) > 0 and self.dbg >= ERR:
log(ERR, '(Layer3 - %s) string not completely mapped\nremaining: ' \
'%s' % (self.CallName, string))
def __map_opts(self, string=''):
# retrieve all optional IE from the Layer3 into opt_ie list
opt_ie = self.__get_opts()
taglist = [ie[0]() for ie in opt_ie if not isinstance(ie, StrRR)]
if self.dbg >= DBG:
log(DBG, '(Layer3 - %s) opt_ie: %s' % (self.CallName, opt_ie))
# go over the string and map to optional IE found
while len(string) > 0:
# check each iteration for the right tag
t = self._select_tag(string[0], taglist)
if t:
string, opt_ie = self.__map_opt(t, string, opt_ie)
taglist.remove(t)
#
else:
if self.dbg >= ERR:
log(WNG, '(Layer3 - %s) unknown optional IE' \
% self.CallName)
# could try to map it as a TLV, or TLVextended, or TV, or T...
# check the TS 24.007, section 11.2.4, for being amazed...
string2 = self.__map_unknown_opt(string)
if string2 == string:
break
string = string2
#
# optional IE that have not been mapped have to go "transparent"
if len(opt_ie) > 0:
[setattr(ie, 'Trans', True) for ie in opt_ie]
if self.dbg >= DBG:
log(DBG, '(Layer3 - %s) not all optional IE used\nremaining:' \
' %s' % (self.CallName, opt_ie))
# this should only happen when __map_unknown_opt() cannot
# consume remaining string.
if len(string) > 0 and self.dbg >= ERR:
log(ERR, '(Layer3 - %s) string not completely mapped\nremaining: ' \
'%s' % (self.CallName, string))
def map(self, string=''):
# Layer3 have optional fields that need special processing
# they all have a tag (attribute .T)
opt_fields = (Type1_TV, Type2, Type3_TV, Type4_TLV, Type6_TLVE)
GSM_RR = False
# handle special string truncature for L3GSM_RR that is on CCCH
# cause opts may not be there, but we still have rest octets to map
if self.CallName in RR_in_CCCH:
if self.safe:
assert (isinstance(self[0], Bit) and self[0].CallName == 'len')
GSM_RR, l2_len = True, self._len_gsmrr(string)
string, rest = string[:l2_len + 1], string[l2_len + 1:]
if self.dbg >= DBG:
log(DBG, '(Layer3 GSM_RR - %s)\nl2len: %i\nstring: %s\nrest: %s' \
% (self.CallName, l2_len, hexlify(string), hexlify(rest)))
# Otherwise we mimic standard Layer().map() behaviour
self._Layer__BitStack = []
self._Layer__BitStack_len = 0
#
for e in self:
# special processing for Bit() element:
if isinstance(e, Bit):
self._Layer__add_to_bitstack(e)
# if BitStack is byte aligned, map string to it:
if self._Layer__BitStack_len % 8 == 0:
if self.dbg >= DBG:
log(DBG, '(Layer3 - %s) mapping %s to bitstack %s' \
% (self.__class__, hexlify(string), \
self._Layer__BitStack))
string = self._Layer__map_to_bitstack(string)
else:
if self._Layer__BitStack_len > 0 and self.dbg >= ERR:
log(ERR, '(Layer3 - %s) some of the Bit elements have not ' \
'been mapped in the "Layer": not byte-aligned' \
% self.CallName)
### special Layer3 processing ###
# need to manage smartly optional / conditionnal fields
# Tagged IE always come after mandatory IE
# so we handle it in another sub method and break the parsing
if isinstance(e, opt_fields):
# for standard L3 messages
self.__map_opts(string)
break
###
# and for mandatory IE (not tagged)
if isinstance(e, (Layer, Element)) and not e.is_transparent():
if self.dbg >= DBG:
log(DBG, '(Layer3 - %s) mapping %s on %s' \
% (self.__class__, hexlify(string), e.CallName))
e.map(string)
string = string[e.map_len():]
# for GSM RR: map rest octets, that comes after tagged IE
if GSM_RR and rest:
if isinstance(self[-1], StrRR):
self[-1].Trans = False
else:
self.append(StrRR('RestOctets', Repr='hex'))
self[-1].map(rest)
# delete .map() *internal* attributes
del self._Layer__BitStack
del self._Layer__BitStack_len
#
### special Layer3 processing ###
if not self._interpret_IE:
return
#
# Go again through all L3 fields that are not transparent
# (tested with their length, WNG: do not work for LV(), however,
# LV field should always be there...)
# and check if L3Mobile_IE is available for even more interpretation
for e in [f for f in self if len(f)]:
cn = e.CallName
if self.dbg >= DBG:
log(DBG, 'L3Mobile_24007 - map: checking for IE %s ' \
'interpretation' % cn)
# truncate possible digit addition at the end of the CallName
# 11/06/2012: this ugly hack is not supported anymore...
# 13/06/2012: this ugly hack is back !
# with an '_' in front of the digit
digit = search('_[1-9]{1,}$', e.CallName)
if digit:
cn = cn[:digit.start()]
# check for potential IE interpretation
#if hasattr(L3Mobile_IE, cn) or hasattr(L3GSM_IE, cn):
if cn in IE_list:
self.interpret_IE(e, cn)
def map(self, string=''):
# Layer3 have optional fields that need special processing
# they all have a tag (attribute .T)
opt_fields = (Type1_TV, Type2, Type3_TV, Type4_TLV, Type6_TLVE)
GSM_RR = False
# handle special string truncature for L3GSM_RR that is on CCCH
# cause opts may not be there, but we still have rest octets to map
if self.CallName in RR_in_CCCH:
if self.safe:
assert(isinstance(self[0], Bit) and self[0].CallName=='len')
GSM_RR, l2_len = True, self._len_gsmrr(string)
string, rest = string[:l2_len+1], string[l2_len+1:]
if self.dbg >= DBG:
log(DBG, '(Layer3 GSM_RR - %s)\nl2len: %i\nstring: %s\nrest: %s' \
% (self.CallName, l2_len, hexlify(string), hexlify(rest)))
# Otherwise we mimic standard Layer().map() behaviour
self._Layer__BitStack = []
self._Layer__BitStack_len = 0
#
for e in self:
# special processing for Bit() element:
if isinstance(e, Bit):
self._Layer__add_to_bitstack(e)
# if BitStack is byte aligned, map string to it:
if self._Layer__BitStack_len % 8 == 0:
if self.dbg >= DBG:
log(DBG, '(Layer3 - %s) mapping %s to bitstack %s' \
% (self.__class__, hexlify(string), \
self._Layer__BitStack))
string = self._Layer__map_to_bitstack(string)
else:
if self._Layer__BitStack_len > 0 and self.dbg >= ERR:
log(ERR, '(Layer3 - %s) some of the Bit elements have not ' \
'been mapped in the "Layer": not byte-aligned' \
% self.CallName)
### special Layer3 processing ###
# need to manage smartly optional / conditionnal fields
# Tagged IE always come after mandatory IE
# so we handle it in another sub method and break the parsing
if isinstance(e, opt_fields):
# for standard L3 messages
self.__map_opts(string)
break
###
# and for mandatory IE (not tagged)
if isinstance(e, (Layer, Element)) and not e.is_transparent():
if self.dbg >= DBG:
log(DBG, '(Layer3 - %s) mapping %s on %s' \
% (self.__class__, hexlify(string), e.CallName))
e.map(string)
string = string[e.map_len():]
# for GSM RR: map rest octets, that comes after tagged IE
if GSM_RR and rest:
if isinstance(self[-1], StrRR):
self[-1].Trans = False
else:
self.append(StrRR('RestOctets', Repr='hex'))
self[-1].map(rest)
# delete .map() *internal* attributes
del self._Layer__BitStack
del self._Layer__BitStack_len
#
### special Layer3 processing ###
if not self._interpret_IE:
return
#
# Go again through all L3 fields that are not transparent
# (tested with their length, WNG: do not work for LV(), however,
# LV field should always be there...)
# and check if L3Mobile_IE is available for even more interpretation
for e in [f for f in self if len(f)]:
cn = e.CallName
if self.dbg >= DBG:
log(DBG, 'L3Mobile_24007 - map: checking for IE %s ' \
'interpretation' % cn)
# truncate possible digit addition at the end of the CallName
# 11/06/2012: this ugly hack is not supported anymore...
# 13/06/2012: this ugly hack is back !
# with an '_' in front of the digit
digit = search('_[1-9]{1,}$', e.CallName)
if digit:
cn = cn[:digit.start()]
# check for potential IE interpretation
#if hasattr(L3Mobile_IE, cn) or hasattr(L3GSM_IE, cn):
if cn in IE_list:
self.interpret_IE(e, cn)
def parse_L3(buf, L2_length_incl=0):
'''
This is a global parser for mobile layer 3 signalling.
It works fine as is with MM, CC, GMM and SM protocols.
For GSM RR signalling, the length of the L2 pseudo-length header (1 byte)
needs to be passed as parameter "L2_length_incl" to retrieve correctly
the protocol discriminator and message type.
E.g. for messages passed over GSM BCCH or CCCH: L2_length_incl=1
parse_L3(string_buffer, L2_length_incl=0) -> Layer3 instance
'''
# select message from PD and Type
if len(buf) < 2:
log(ERR, '(parse_L3) message too short for L3 mobile')
return RawLayer(buf)
#
###
# Protocol Discriminator
###
# protocol discriminator is 4 last bits (LSB) of 1st byte
PD = ord(buf[L2_length_incl]) & 0x0F
#
###
# Message Type
###
# for MM, CC, SS and GSM RR, only 6 1st bits for the message type
if PD in (3, 5, 6, 11):
Type = ord(buf[L2_length_incl+1]) & 0x3F
#
# for LTE NAS messages: message content (including Type) can be ciphered
# (the security processing is available in the Layer3NAS class)
# EMM header has a security header
elif PD == 7:
# check Security Header
SH = ord(buf[L2_length_incl]) >> 4
# no security:
if SH == 0:
Type = ord(buf[1])
# integrity protection only:
elif SH in (1, 3):
if len(buf) < 8:
Type = None
Type = ord(buf[7])
# ciphering, hence not possible to know the payload Type
elif SH in (2, 4):
Type = None
elif SH == 12 and len(buf) >= 4:
# LTE NAS service request
l3 = SERVICE_REQUEST()
l3.map(buf)
return l3
else:
log(WNG, '(parse_L3) unknown NAS EMM security header: %i' % SH)
Type = None
#
# ESM header has bearer ID in the 4 MSB of 1st byte
# and Transaction ID between PD and Type
elif PD == 2:
if len(buf) < 3:
Type = None
Type = ord(buf[2])
#
# for other 2G and 3G core protocols (GMM, SM, SMS, ...), nothing special
else:
Type = ord(buf[L2_length_incl+1])
#
if PD not in L3Call:
if PD not in PD_dict:
log(ERR, '(parse_L3) unknown L3 protocol discriminator: %i' % PD)
else:
log(WNG, '(parse_L3) L3 protocol %s not implemented' % PD_dict[PD])
l3 = RawL3()
l3.map(buf)
#
# get the right type from Type
elif Type not in L3Call[PD] and Type is not None:
log(ERR, '(parse_L3) L3 message type %i undefined for protocol %s' \
% (Type, PD_dict[PD]))
l3 = RawL3()
l3.map(buf)
# for L3GSM_RR, still use the msg type dict:
# because GSM RR are not all implemented
if PD == 6:
l3.Type.Dict = GSM_RR_dict
#
# select the correct L3 signalling message
else:
# for LTE NAS, if ciphered
#log(DBG, '(parse_L3) PD %i, Type %i' % (PD, Type))
if Type is None:
l3 = Layer3NAS(with_security=True)
else:
l3 = L3Call[PD][Type]()
#
try:
#log(DBG, '(parse_L3) mapping ?')
l3.map(buf)
#log(DBG, '(parse_L3) mapped correctly')
except:
log(ERR, '(parse_L3) mapping buffer on L3 message failed')
l3 = RawL3()
l3.map(buf)
#
return l3
def test_regr(print_infos=True):
'''
L3GSM_RR and L3Mobile_* regression testing:
checking all signalling messages from the L3Call dictionnary
'''
# libmich settings
e_safe = Element.safe
l_safe = Layer.safe
Element.safe = True
Layer.safe = True
Element.dbg = ERR
Layer.dbg = ERR
#
glob_errors = 0
#
def test_dict():
e = 0
for pd in L3Call:
for msg in L3Call[pd]:
error = ''
cl = L3Call[pd][msg]
if not issubclass(cl, Layer3):
log(WNG, 'message %s not subclass of Layer3' % repr(cl))
else:
try:
m = cl(with_options=True)
except:
error = '__init__(with_options=True)'
else:
try:
buf = str(m)
except:
error = '__str__()'
else:
try:
m2 = cl(with_options=False)
m2.parse(buf)
except:
error = 'parse()'
else:
if str(m2) != buf:
error = '__str__() result discrepancy ' + \
' with parse()d buffer'
if error:
log(ERR, 'message %s test returns error: %s' \
% (repr(cl), error))
e += 1
return e
#
Layer3._initiator = 'Net'
if print_infos:
log(DBG, 'testing with Net initiator')
glob_errors += test_dict()
Layer3._initiator = 'ME'
if print_infos:
log(DBG, 'testing with ME initiator')
glob_errors += test_dict()
#
Element.safe = e_safe
Layer.safe = l_safe
#
if not glob_errors and print_infos:
log(DBG, '[Heeeeha!!!] all L3Mobile tests passed successfully')
return glob_errors
def parse_L3(buf, L2_length_incl=0):
'''
This is a global parser for mobile layer 3 signalling.
It works fine as is with MM, CC, GMM and SM protocols.
For GSM RR signalling, the length of the L2 pseudo-length header (1 byte)
needs to be passed as parameter "L2_length_incl" to retrieve correctly
the protocol discriminator and message type.
E.g. for messages passed over GSM BCCH or CCCH: L2_length_incl=1
parse_L3(string_buffer, L2_length_incl=0) -> Layer3 instance
'''
# select message from PD and Type
if len(buf) < 2:
log(ERR, '(parse_L3) message too short for L3 mobile')
return RawLayer(buf)
#
###
# Protocol Discriminator
###
# protocol discriminator is 4 last bits (LSB) of 1st byte
PD = ord(buf[L2_length_incl]) & 0x0F
#
###
# Message Type
###
# for MM, CC, SS and GSM RR, only 6 1st bits for the message type
if PD in (3, 5, 6, 11):
Type = ord(buf[L2_length_incl + 1]) & 0x3F
#
# for LTE NAS messages: message content (including Type) can be ciphered
# (the security processing is available in the Layer3NAS class)
# EMM header has a security header
elif PD == 7:
# check Security Header
SH = ord(buf[L2_length_incl]) >> 4
# no security:
if SH == 0:
Type = ord(buf[1])
# integrity protection only:
elif SH in (1, 3):
if len(buf) < 8:
Type = None
Type = ord(buf[7])
# ciphering, hence not possible to know the payload Type
elif SH in (2, 4):
Type = None
elif SH == 12 and len(buf) >= 4:
# LTE NAS service request
l3 = SERVICE_REQUEST()
l3.map(buf)
return l3
else:
log(WNG, '(parse_L3) unknown NAS EMM security header: %i' % SH)
Type = None
#
# ESM header has bearer ID in the 4 MSB of 1st byte
# and Transaction ID between PD and Type
elif PD == 2:
if len(buf) < 3:
Type = None
Type = ord(buf[2])
#
# for other 2G and 3G core protocols (GMM, SM, SMS, ...), nothing special
else:
Type = ord(buf[L2_length_incl + 1])
#
if PD not in L3Call:
if PD not in PD_dict:
log(ERR, '(parse_L3) unknown L3 protocol discriminator: %i' % PD)
else:
log(WNG, '(parse_L3) L3 protocol %s not implemented' % PD_dict[PD])
l3 = RawL3()
l3.map(buf)
#
# get the right type from Type
elif Type not in L3Call[PD] and Type is not None:
log(ERR, '(parse_L3) L3 message type %i undefined for protocol %s' \
% (Type, PD_dict[PD]))
l3 = RawL3()
l3.map(buf)
# for L3GSM_RR, still use the msg type dict:
# because GSM RR are not all implemented
if PD == 6:
l3.Type.Dict = GSM_RR_dict
#
# select the correct L3 signalling message
else:
# for LTE NAS, if ciphered
#log(DBG, '(parse_L3) PD %i, Type %i' % (PD, Type))
if Type is None:
l3 = Layer3NAS(with_security=True)
else:
l3 = L3Call[PD][Type]()
#
try:
#log(DBG, '(parse_L3) mapping ?')
l3.map(buf)
#log(DBG, '(parse_L3) mapped correctly')
except:
log(ERR, '(parse_L3) mapping buffer on L3 message failed')
l3 = RawL3()
l3.map(buf)
#
return l3
def test_regr(print_infos=True):
'''
L3GSM_RR and L3Mobile_* regression testing:
checking all signalling messages from the L3Call dictionnary
'''
# libmich settings
e_safe = Element.safe
l_safe = Layer.safe
Element.safe = True
Layer.safe = True
Element.dbg = ERR
Layer.dbg = ERR
#
glob_errors = 0
#
def test_dict():
e = 0
for pd in L3Call:
for msg in L3Call[pd]:
error = ''
cl = L3Call[pd][msg]
if not issubclass(cl, Layer3):
log(WNG, 'message %s not subclass of Layer3' % repr(cl))
else:
try:
m = cl(with_options=True)
except:
error = '__init__(with_options=True)'
else:
try:
buf = str(m)
except:
error = '__str__()'
else:
try:
m2 = cl(with_options=False)
m2.parse(buf)
except:
error = 'parse()'
else:
if str(m2) != buf:
error = '__str__() result discrepancy ' + \
' with parse()d buffer'
if error:
log(ERR, 'message %s test returns error: %s' \
% (repr(cl), error))
e += 1
return e
#
Layer3._initiator = 'Net'
if print_infos:
log(DBG, 'testing with Net initiator')
glob_errors += test_dict()
Layer3._initiator = 'ME'
if print_infos:
log(DBG, 'testing with ME initiator')
glob_errors += test_dict()
#
Element.safe = e_safe
Layer.safe = l_safe
#
if not glob_errors and print_infos:
log(DBG, '[Heeeeha!!!] all L3Mobile tests passed successfully')
return glob_errors
#
#
def unprotect(self, key_int=16*'\0', key_enc=16*'\0', dir=0):
ret = self.verify_mac(key_int, dir)
if not ret:
log(WNG, 'Layer3NAS - unprotect: MAC verificaion failed')
self.decipher(key_enc, dir)
