def encode_7b(txt):
"""translates the unicode string `txt' to a GSM 7 bit characters buffer
"""
arr, cnt = [], 0
for c in reversed(txt):
try:
arr.append((TYPE_UINT, _GSM7bLUTInv[c], 7))
except KeyError:
try:
arr.append((TYPE_UINT, _GSM7bExtLUTInv[c], 7))
except KeyError:
raise (PycrateErr('invalid GSM 7 bit char: %r' % c))
else:
# add an escape char
arr.append((TYPE_UINT, 27, 7))
cnt += 2
else:
cnt += 1
# check the length in bits and add padding bits
pad = (8 - (7 * len(arr)) % 8) % 8
arr.insert(0, (TYPE_UINT, 0, pad))
if python_version < 3:
return ''.join(reversed(pack_val(*arr)[0])), cnt
else:
return bytes(reversed(pack_val(*arr)[0])), cnt
def encode_7b(txt, off=0):
"""translates the unicode string `txt' to a GSM 7 bit characters buffer
Args:
txt (utf8 str): text string to encode
off (uint): bit offset
Returns:
encoded buffer and septet count (bytes, uint)
"""
arr, cnt = [], 0
for c in reversed(txt):
try:
arr.append( (TYPE_UINT, _GSM7bLUTInv[c], 7) )
except KeyError:
try:
arr.append( (TYPE_UINT, _GSM7bExtLUTInv[c], 7) )
except KeyError:
raise(PycrateErr('invalid GSM 7 bit char: %r' % c))
else:
# add an escape char
arr.append( (TYPE_UINT, 27, 7) )
cnt += 2
else:
cnt += 1
# check the length in bits and add padding bits
pad = ((8-(7*len(arr)+off)%8)%8)
arr.insert(0, (TYPE_UINT, 0, pad))
if python_version < 3:
return ''.join(reversed(pack_val(*arr)[0])), cnt
else:
return bytes(reversed(pack_val(*arr)[0])), cnt
def add_segment_and_decode(self, radio_bearer, sfn_prime, sib_type,
segment_index, is_final, segment_data_int,
segment_data_bitlen, on_sib_decoding_error):
if (self.last_sfn and not (1 <= sfn_prime - self.last_sfn <= 16)) or \
(len(self.segment_bitstrings) != segment_index):
on_sib_decoding_error(
'DEBUG: Uncomplete %s reassembly: SFN jump from %s to %s (%d), index expected to be %d but is %d'
% (getattr(self, 'sib_type', sib_type), self.last_sfn,
sfn_prime, sfn_prime - (self.last_sfn or 0),
len(self.segment_bitstrings), segment_index))
self.__init__() # Reset state
if len(self.segment_bitstrings) != segment_index:
return
if not segment_index:
self.first_sfn = sfn_prime
self.last_sfn = sfn_prime
self.segment_bitstrings.append(
[TYPE_UINT, segment_data_int, segment_data_bitlen])
if is_final:
# Convert segments bitstrings to bytes
sib_byte_string = pack_val(*self.segment_bitstrings)[0]
"""
From spec: "If the value "Extension Type" is signalled,
the UE shall use the scheduling information in
the MIB and, if present, in the SB1 and SB2 to
identify the specific type of system information
block."
"""
if sib_type == 'extensionType':
for sib_schedule, sib_ext_type in bearer_to_sib_schedule_to_sib_type[
radio_bearer].items():
if self.first_sfn % sib_schedule.sib_period == sib_schedule.sib_position and \
len(self.segment_bitstrings) == sib_schedule.num_segments:
self.sib_type = sib_type = sib_ext_type
if sib_type == 'extensionType':
on_sib_decoding_error(
'DEBUG: Received an extensionType SIB with SFN %d for which no scheduling information is known from MIB/SBs'
% sfn_prime)
return
sib_object = SIB_NAME_TO_CLASS[sib_type]
try:
sib_object.from_uper(sib_byte_string)
except Exception:
on_sib_decoding_error(
'ERROR: SIB decoding failed for %s (%s): %s' %
(sib_type, repr(sib_byte_string), format_exc()))
return
sib_dict = sib_object()
# Reset state
self.__init__()
return sib_type, sib_dict, sib_byte_string