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per.py
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per.py
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"""Aligned Packed Encoding Rules (PER) codec.
"""
from operator import attrgetter
from operator import itemgetter
import binascii
import string
import datetime
from ..parser import EXTENSION_MARKER
from . import EncodeError
from . import DecodeError
from . import OutOfDataError
from . import compiler
from . import format_or
from . import restricted_utc_time_to_datetime
from . import restricted_utc_time_from_datetime
from . import restricted_generalized_time_to_datetime
from . import restricted_generalized_time_from_datetime
from .compiler import enum_values_split
from .compiler import clean_bit_string_value
from .compiler import rstrip_bit_string_zeros
from .ber import encode_real
from .ber import decode_real
from .ber import encode_object_identifier
from .ber import decode_object_identifier
from .permitted_alphabet import NUMERIC_STRING
from .permitted_alphabet import PRINTABLE_STRING
from .permitted_alphabet import IA5_STRING
from .permitted_alphabet import VISIBLE_STRING
def is_unbound(minimum, maximum):
return minimum in [None, 'MIN'] or maximum in [None, 'MAX']
def integer_as_number_of_bits(size):
"""Returns the minimum number of bits needed to fit given positive
integer.
"""
if size == 0:
return 0
else:
return size.bit_length()
def integer_as_number_of_bits_power_of_two(size):
"""Returns the minimum power of two number of bits needed to fit given
positive integer.
"""
if size == 0:
return 0
else:
bit_length = integer_as_number_of_bits(size)
bit_length_pow_2 = 1
while bit_length > bit_length_pow_2:
bit_length_pow_2 <<= 1
return bit_length_pow_2
def size_as_number_of_bytes(size):
"""Returns the minimum number of bytes needed to fit given positive
integer.
"""
if size == 0:
return 1
else:
number_of_bits = size.bit_length()
rest = (number_of_bits % 8)
if rest != 0:
number_of_bits += (8 - rest)
return number_of_bits // 8
CLASS_PRIO = {
'UNIVERSAL': 0,
'APPLICATION': 1,
'CONTEXT_SPECIFIC': 2,
'PRIVATE': 3
}
class PermittedAlphabet(object):
def __init__(self, encode_map, decode_map):
self.encode_map = encode_map
self.decode_map = decode_map
def __len__(self):
return len(self.encode_map)
def encode(self, value):
try:
return self.encode_map[value]
except KeyError:
raise EncodeError(
"Expected a character in '{}', but got '{}' (0x{:02x})'.".format(
''.join(sorted([chr(v) for v in self.encode_map])),
chr(value) if chr(value) in string.printable else '.',
value))
def decode(self, value):
try:
return self.decode_map[value]
except KeyError:
raise DecodeError(
"Expected a value in {}, but got {:d}.".format(
list(self.decode_map),
value))
class Encoder(object):
def __init__(self):
self.number_of_bits = 0
self.value = 0
self.chunks_number_of_bits = 0
self.chunks = []
def __iadd__(self, other):
for value, number_of_bits in other.chunks:
self.append_non_negative_binary_integer(value, number_of_bits)
self.append_non_negative_binary_integer(other.value,
other.number_of_bits)
return self
def reset(self):
self.number_of_bits = 0
self.value = 0
self.chunks_number_of_bits = 0
self.chunks = []
def are_all_bits_zero(self):
return not (any([value for value, _ in self.chunks]) or self.value)
def number_of_bytes(self):
return (self.chunks_number_of_bits + self.number_of_bits + 7) // 8
def offset(self):
return (len(self.chunks), self.number_of_bits)
def set_bit(self, offset):
chunk_offset, bit_offset = offset
if len(self.chunks) == chunk_offset:
self.value |= (1 << (self.number_of_bits - bit_offset - 1))
else:
chunk = self.chunks[chunk_offset]
chunk[0] |= (1 << (chunk[1] - bit_offset - 1))
def align(self):
self.align_always()
def align_always(self):
width = 8 * self.number_of_bytes()
width -= self.chunks_number_of_bits
width -= self.number_of_bits
self.number_of_bits += width
self.value <<= width
def append_bit(self, bit):
"""Append given bit.
"""
self.number_of_bits += 1
self.value <<= 1
self.value |= bit
def append_bits(self, data, number_of_bits):
"""Append given bits.
"""
if number_of_bits == 0:
return
value = int(binascii.hexlify(data), 16)
value >>= (8 * len(data) - number_of_bits)
self.append_non_negative_binary_integer(value, number_of_bits)
def append_non_negative_binary_integer(self, value, number_of_bits):
"""Append given integer value.
"""
if self.number_of_bits > 4096:
self.chunks.append([self.value, self.number_of_bits])
self.chunks_number_of_bits += self.number_of_bits
self.number_of_bits = 0
self.value = 0
self.number_of_bits += number_of_bits
self.value <<= number_of_bits
self.value |= value
def append_bytes(self, data):
"""Append given data.
"""
self.append_bits(data, 8 * len(data))
def as_bytearray(self):
"""Return the bits as a bytearray.
"""
value = 0
number_of_bits = 0
for chunk_value, chunk_number_of_bits in self.chunks:
value <<= chunk_number_of_bits
value |= chunk_value
number_of_bits += chunk_number_of_bits
value <<= self.number_of_bits
value |= self.value
number_of_bits += self.number_of_bits
if number_of_bits == 0:
return bytearray()
number_of_alignment_bits = (8 - (number_of_bits % 8))
if number_of_alignment_bits != 8:
value <<= number_of_alignment_bits
number_of_bits += number_of_alignment_bits
value |= (0x80 << number_of_bits)
value = hex(value)[4:].rstrip('L')
return bytearray(binascii.unhexlify(value))
def append_length_determinant(self, length):
if length < 128:
encoded = bytearray([length])
elif length < 16384:
encoded = bytearray([(0x80 | (length >> 8)), (length & 0xff)])
elif length < 32768:
encoded = b'\xc1'
length = 16384
elif length < 49152:
encoded = b'\xc2'
length = 32768
elif length < 65536:
encoded = b'\xc3'
length = 49152
else:
encoded = b'\xc4'
length = 65536
self.append_bytes(encoded)
return length
def append_length_determinant_chunks(self, length):
offset = 0
chunk_length = length
while True:
chunk_length = self.append_length_determinant(chunk_length)
yield offset, chunk_length
if chunk_length < 16384:
break
offset += chunk_length
chunk_length = length - offset
def append_normally_small_non_negative_whole_number(self, value):
if value < 64:
self.append_non_negative_binary_integer(value, 7)
else:
self.append_bit(1)
length = (value.bit_length() + 7) // 8
self.append_length_determinant(length)
self.append_non_negative_binary_integer(value, 8 * length)
def append_normally_small_length(self, value):
if value <= 64:
self.append_non_negative_binary_integer(value - 1, 7)
elif value <= 127:
self.append_non_negative_binary_integer(0x100 | value, 9)
else:
raise NotImplementedError(
'Normally small length number >127 is not yet supported.')
def append_constrained_whole_number(self,
value,
minimum,
maximum,
number_of_bits):
_range = (maximum - minimum + 1)
if _range <= 255:
self.append_non_negative_binary_integer(value - minimum,
number_of_bits)
elif _range == 256:
self.align_always()
self.append_non_negative_binary_integer(value - minimum, 8)
elif _range <= 65536:
self.align_always()
self.append_non_negative_binary_integer(value - minimum, 16)
else:
number_of_bits = size_as_number_of_bytes(value) * 8
self.align_always()
self.append_non_negative_binary_integer(value - minimum,
number_of_bits)
def append_unconstrained_whole_number(self, value):
number_of_bits = value.bit_length()
if value < 0:
number_of_bytes = ((number_of_bits + 7) // 8)
value = ((1 << (8 * number_of_bytes)) + value)
if (value & (1 << (8 * number_of_bytes - 1))) == 0:
value |= (0xff << (8 * number_of_bytes))
number_of_bytes += 1
elif value > 0:
number_of_bytes = ((number_of_bits + 7) // 8)
if number_of_bits == (8 * number_of_bytes):
number_of_bytes += 1
else:
number_of_bytes = 1
self.append_length_determinant(number_of_bytes)
self.append_non_negative_binary_integer(value,
8 * number_of_bytes)
def __repr__(self):
return binascii.hexlify(self.as_bytearray()).decode('ascii')
class Decoder(object):
def __init__(self, encoded):
self.number_of_bits = (8 * len(encoded))
self.total_number_of_bits = self.number_of_bits
if len(encoded) > 0:
value = int(binascii.hexlify(encoded), 16)
value |= (0x80 << self.number_of_bits)
self.value = bin(value)[10:]
else:
self.value = ''
def align(self):
self.align_always()
def align_always(self):
width = (self.number_of_bits & 0x7)
self.number_of_bits -= width
def number_of_read_bits(self):
return self.total_number_of_bits - self.number_of_bits
def skip_bits(self, number_of_bits):
if number_of_bits > self.number_of_bits:
raise OutOfDataError(self.number_of_read_bits())
self.number_of_bits -= number_of_bits
def read_bit(self):
"""Read a bit.
"""
if self.number_of_bits == 0:
raise OutOfDataError(self.number_of_read_bits())
bit = int(self.value[self.number_of_read_bits()])
self.number_of_bits -= 1
return bit
def read_bits(self, number_of_bits):
"""Read given number of bits.
"""
if number_of_bits > self.number_of_bits:
raise OutOfDataError(self.number_of_read_bits())
offset = self.number_of_read_bits()
value = self.value[offset:offset + number_of_bits]
self.number_of_bits -= number_of_bits
value = '10000000' + value
number_of_alignment_bits = (8 - (number_of_bits % 8))
if number_of_alignment_bits != 8:
value += '0' * number_of_alignment_bits
return binascii.unhexlify(hex(int(value, 2))[4:].rstrip('L'))
def read_bytes(self, number_of_bytes):
return self.read_bits(8 * number_of_bytes)
def read_non_negative_binary_integer(self, number_of_bits):
"""Read an integer value of given number of bits.
"""
if number_of_bits > self.number_of_bits:
raise OutOfDataError(self.number_of_read_bits())
if number_of_bits == 0:
return 0
offset = self.number_of_read_bits()
value = self.value[offset:offset + number_of_bits]
self.number_of_bits -= number_of_bits
return int(value, 2)
def read_length_determinant(self):
value = self.read_non_negative_binary_integer(8)
if (value & 0x80) == 0x00:
return value
elif (value & 0xc0) == 0x80:
return (((value & 0x7f) << 8)
| (self.read_non_negative_binary_integer(8)))
else:
try:
return {
0xc1: 16384,
0xc2: 32768,
0xc3: 49152,
0xc4: 65536
}[value]
except KeyError:
raise DecodeError(
'Bad length determinant fragmentation value 0x{:02x}.'.format(
value))
def read_length_determinant_chunks(self):
while True:
length = self.read_length_determinant()
yield length
if length < 16384:
break
def read_normally_small_non_negative_whole_number(self):
if not self.read_bit():
decoded = self.read_non_negative_binary_integer(6)
else:
length = self.read_length_determinant()
decoded = self.read_non_negative_binary_integer(8 * length)
return decoded
def read_normally_small_length(self):
if not self.read_bit():
return self.read_non_negative_binary_integer(6) + 1
elif not self.read_bit():
return self.read_non_negative_binary_integer(7)
else:
raise NotImplementedError(
'Normally small length number >64 is not yet supported.')
def read_constrained_whole_number(self,
minimum,
maximum,
number_of_bits):
_range = (maximum - minimum + 1)
if _range <= 255:
value = self.read_non_negative_binary_integer(number_of_bits)
elif _range == 256:
self.align_always()
value = self.read_non_negative_binary_integer(8)
elif _range <= 65536:
self.align_always()
value = self.read_non_negative_binary_integer(16)
else:
self.align_always()
value = self.read_non_negative_binary_integer(number_of_bits)
return value + minimum
def read_unconstrained_whole_number(self):
length = self.read_length_determinant()
decoded = self.read_non_negative_binary_integer(8 * length)
number_of_bits = (8 * length)
if decoded & (1 << (number_of_bits - 1)):
mask = ((1 << number_of_bits) - 1)
decoded = (decoded - mask)
decoded -= 1
return decoded
class Type(object):
def __init__(self, name, type_name):
self.name = name
self.type_name = type_name
self.optional = False
self.default = None
self.tag = None
def set_size_range(self, minimum, maximum, has_extension_marker):
pass
def set_restricted_to_range(self, minimum, maximum, has_extension_marker):
pass
def is_default(self, value):
return value == self.default
class KnownMultiplierStringType(Type):
PERMITTED_ALPHABET = PermittedAlphabet({}, {})
def __init__(self,
name,
minimum=None,
maximum=None,
has_extension_marker=False,
permitted_alphabet=None):
super(KnownMultiplierStringType, self).__init__(name,
self.__class__.__name__)
self.set_size_range(minimum, maximum, has_extension_marker)
if permitted_alphabet is None:
permitted_alphabet = self.PERMITTED_ALPHABET
self.permitted_alphabet = permitted_alphabet
self.bits_per_character = integer_as_number_of_bits_power_of_two(
len(permitted_alphabet) - 1)
if len(self.PERMITTED_ALPHABET) < 2 ** self.bits_per_character:
self.permitted_alphabet = self.PERMITTED_ALPHABET
def set_size_range(self, minimum, maximum, has_extension_marker):
self.minimum = minimum
self.maximum = maximum
self.has_extension_marker = has_extension_marker
if is_unbound(minimum, maximum):
self.number_of_bits = None
else:
size = maximum - minimum
self.number_of_bits = integer_as_number_of_bits(size)
def encode(self, data, encoder):
encoded = bytearray(data.encode('ascii'))
if self.has_extension_marker:
if self.minimum <= len(encoded) <= self.maximum:
encoder.append_bit(0)
else:
raise NotImplementedError(
'String size extension is not yet implemented.')
if self.number_of_bits is None:
return self.encode_unbound(encoded, encoder)
elif self.minimum != self.maximum:
encoder.append_constrained_whole_number(len(encoded),
self.minimum,
self.maximum,
self.number_of_bits)
if self.maximum > 1:
encoder.align()
elif self.maximum * self.bits_per_character > 16:
encoder.align()
for value in encoded:
encoder.append_non_negative_binary_integer(
self.permitted_alphabet.encode(value),
self.bits_per_character)
def encode_unbound(self, encoded, encoder):
encoder.align()
for offset, length in encoder.append_length_determinant_chunks(len(encoded)):
for entry in encoded[offset:offset + length]:
encoder.append_non_negative_binary_integer(
self.permitted_alphabet.encode(entry),
self.bits_per_character)
def decode(self, decoder):
if self.has_extension_marker:
bit = decoder.read_bit()
if bit:
raise NotImplementedError(
'String size extension is not yet implemented.')
if self.number_of_bits is None:
return self.decode_unbound(decoder)
else:
if self.minimum != self.maximum:
length = decoder.read_constrained_whole_number(self.minimum,
self.maximum,
self.number_of_bits)
if self.maximum > 1:
decoder.align()
elif self.maximum * self.bits_per_character > 16:
decoder.align()
length = self.minimum
else:
length = self.minimum
data = []
for _ in range(length):
value = decoder.read_non_negative_binary_integer(self.bits_per_character)
data.append(self.permitted_alphabet.decode(value))
return bytearray(data).decode('ascii')
def decode_unbound(self, decoder):
decoder.align()
decoded = []
for length in decoder.read_length_determinant_chunks():
for _ in range(length):
value = decoder.read_non_negative_binary_integer(
self.bits_per_character)
decoded.append(self.permitted_alphabet.decode(value))
return bytearray(decoded).decode('ascii')
def __repr__(self):
return '{}({})'.format(self.__class__.__name__,
self.name)
class StringType(Type):
ENCODING = None
LENGTH_MULTIPLIER = 1
def __init__(self, name):
super(StringType, self).__init__(name, self.__class__.__name__)
def encode(self, data, encoder):
encoded = data.encode(self.ENCODING)
encoder.align()
for offset, length in encoder.append_length_determinant_chunks(len(data)):
offset *= self.LENGTH_MULTIPLIER
data = encoded[offset:offset + self.LENGTH_MULTIPLIER * length]
encoder.append_bytes(data)
def decode(self, decoder):
decoder.align()
encoded = []
for length in decoder.read_length_determinant_chunks():
encoded.append(decoder.read_bytes(self.LENGTH_MULTIPLIER * length))
return b''.join(encoded).decode(self.ENCODING)
def __repr__(self):
return '{}({})'.format(self.__class__.__name__,
self.name)
class MembersType(Type):
def __init__(self,
name,
root_members,
additions,
type_name):
super(MembersType, self).__init__(name, type_name)
self.root_members = root_members
self.additions = additions
self.optionals = [
member
for member in root_members
if member.optional or member.default is not None
]
def encode(self, data, encoder):
if self.additions is not None:
offset = encoder.offset()
encoder.append_bit(0)
self.encode_root(data, encoder)
if len(self.additions) > 0:
if self.encode_additions(data, encoder):
encoder.set_bit(offset)
else:
self.encode_root(data, encoder)
def encode_root(self, data, encoder):
for optional in self.optionals:
if optional.optional:
encoder.append_bit(optional.name in data)
elif optional.name in data:
encoder.append_bit(not optional.is_default(data[optional.name]))
else:
encoder.append_bit(0)
for member in self.root_members:
self.encode_member(member, data, encoder)
def encode_additions(self, data, encoder):
# Encode extension additions.
presence_bits = 0
addition_encoders = []
number_of_precence_bits = 0
try:
for addition in self.additions:
presence_bits <<= 1
addition_encoder = encoder.__class__()
number_of_precence_bits += 1
if isinstance(addition, AdditionGroup):
addition.encode_addition_group(data, addition_encoder)
else:
self.encode_member(addition,
data,
addition_encoder,
encode_default=True)
if addition_encoder.number_of_bits > 0:
addition_encoders.append(addition_encoder)
presence_bits |= 1
except EncodeError:
pass
# Return false if no extension additions are present.
if not addition_encoders:
return False
# Presence bit field.
number_of_additions = len(self.additions)
presence_bits <<= (number_of_additions - number_of_precence_bits)
encoder.append_normally_small_length(number_of_additions)
encoder.append_non_negative_binary_integer(presence_bits,
number_of_additions)
# Embed each encoded extension addition in an open type (add a
# length field and multiple of 8 bits).
encoder.align()
for addition_encoder in addition_encoders:
addition_encoder.align_always()
encoder.append_length_determinant(addition_encoder.number_of_bytes())
encoder += addition_encoder
return True
def encode_addition_group(self, data, encoder):
self.encode_root(data, encoder)
if (encoder.are_all_bits_zero()
and (encoder.number_of_bits == len(self.optionals))):
encoder.reset()
def encode_member(self, member, data, encoder, encode_default=False):
name = member.name
if name in data:
try:
if member.default is None:
member.encode(data[name], encoder)
elif not member.is_default(data[name]) or encode_default:
member.encode(data[name], encoder)
except EncodeError as e:
e.location.append(member.name)
raise
elif member.optional or member.default is not None:
pass
else:
raise EncodeError(
"{} member '{}' not found in {}.".format(
self.__class__.__name__,
name,
data))
def decode(self, decoder):
if self.additions is not None:
if decoder.read_bit():
decoded = self.decode_root(decoder)
decoded.update(self.decode_additions(decoder))
else:
decoded = self.decode_root(decoder)
else:
decoded = self.decode_root(decoder)
return decoded
def decode_root(self, decoder):
values = {}
optionals = {
optional: decoder.read_bit()
for optional in self.optionals
}
for member in self.root_members:
try:
if optionals.get(member, True):
value = member.decode(decoder)
values[member.name] = value
elif member.default is not None:
values[member.name] = member.default
except DecodeError as e:
e.location.append(member.name)
raise
return values
def decode_additions(self, decoder):
# Presence bit field.
length = decoder.read_normally_small_length()
presence_bits = decoder.read_non_negative_binary_integer(length)
decoder.align()
decoded = {}
for i in range(length):
if presence_bits & (1 << (length - i - 1)):
# Open type decoding.
open_type_length = decoder.read_length_determinant()
offset = decoder.number_of_bits
if i < len(self.additions):
addition = self.additions[i]
if isinstance(addition, AdditionGroup):
decoded.update(addition.decode(decoder))
else:
try:
decoded[addition.name] = addition.decode(decoder)
except DecodeError as e:
e.location.append(addition.name)
raise
else:
decoder.skip_bits(8 * open_type_length)
alignment_bits = (offset - decoder.number_of_bits) % 8
if alignment_bits != 0:
decoder.skip_bits(8 - alignment_bits)
return decoded
def __repr__(self):
return '{}({}, [{}])'.format(
self.__class__.__name__,
self.name,
', '.join([repr(member) for member in self.root_members]))
class ArrayType(Type):
def __init__(self,
name,
element_type,
minimum,
maximum,
has_extension_marker,
type_name):
super(ArrayType, self).__init__(name, type_name)
self.element_type = element_type
self.minimum = minimum
self.maximum = maximum
self.has_extension_marker = has_extension_marker
if is_unbound(minimum, maximum):
self.number_of_bits = None
else:
size = maximum - minimum
self.number_of_bits = integer_as_number_of_bits(size)
def encode(self, data, encoder):
if self.has_extension_marker:
if self.minimum <= len(data) <= self.maximum:
encoder.append_bit(0)
else:
encoder.append_bit(1)
encoder.align()
encoder.append_length_determinant(len(data))
for entry in data:
self.element_type.encode(entry, encoder)
return
if self.number_of_bits is None:
return self.encode_unbound(data, encoder)
elif self.minimum != self.maximum:
encoder.append_constrained_whole_number(len(data),
self.minimum,
self.maximum,
self.number_of_bits)
for entry in data:
self.element_type.encode(entry, encoder)
def encode_unbound(self, data, encoder):
encoder.align()
for offset, length in encoder.append_length_determinant_chunks(len(data)):
for entry in data[offset:offset + length]:
self.element_type.encode(entry, encoder)
def decode(self, decoder):
length = None
if self.has_extension_marker:
bit = decoder.read_bit()
if bit:
decoder.align()
length = decoder.read_length_determinant()
if length is not None:
pass
elif self.number_of_bits is None:
return self.decode_unbound(decoder)
elif self.minimum != self.maximum:
length = decoder.read_constrained_whole_number(self.minimum,
self.maximum,
self.number_of_bits)
else:
length = self.minimum
decoded = []
for _ in range(length):
decoded_element = self.element_type.decode(decoder)
decoded.append(decoded_element)
return decoded
def decode_unbound(self, decoder):
decoder.align()
decoded = []
for length in decoder.read_length_determinant_chunks():
for _ in range(length):
decoded_element = self.element_type.decode(decoder)
decoded.append(decoded_element)
return decoded
def __repr__(self):
return '{}({}, {})'.format(self.__class__.__name__,
self.name,
self.element_type)
class Boolean(Type):
def __init__(self, name):
super(Boolean, self).__init__(name, 'BOOLEAN')
def encode(self, data, encoder):
encoder.append_bit(bool(data))
def decode(self, decoder):
return bool(decoder.read_bit())
def __repr__(self):
return 'Boolean({})'.format(self.name)
class Integer(Type):
def __init__(self, name):
super(Integer, self).__init__(name, 'INTEGER')
self.minimum = None
self.maximum = None
self.has_extension_marker = False
self.number_of_bits = None
self.number_of_indefinite_bits = None
def set_restricted_to_range(self, minimum, maximum, has_extension_marker):
self.has_extension_marker = has_extension_marker