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#
# This file is part of pyasn1 software.
#
# Copyright (c) 2005-2019, Ilya Etingof <etingof@gmail.com>
# License: http://snmplabs.com/pyasn1/license.html
#
from pyasn1 import error
from pyasn1.codec.ber import encoder
from pyasn1.compat.octets import str2octs, null
from pyasn1.type import univ
from pyasn1.type import useful
__all__ = ['encode']
class BooleanEncoder(encoder.IntegerEncoder):
def encodeValue(self, value, asn1Spec, encodeFun, **options):
if value == 0:
substrate = (0,)
else:
substrate = (255,)
return substrate, False, False
class RealEncoder(encoder.RealEncoder):
def _chooseEncBase(self, value):
m, b, e = value
return self._dropFloatingPoint(m, b, e)
# specialized GeneralStringEncoder here
class TimeEncoderMixIn(object):
Z_CHAR = ord('Z')
PLUS_CHAR = ord('+')
MINUS_CHAR = ord('-')
COMMA_CHAR = ord(',')
DOT_CHAR = ord('.')
ZERO_CHAR = ord('0')
MIN_LENGTH = 12
MAX_LENGTH = 19
def encodeValue(self, value, asn1Spec, encodeFun, **options):
# CER encoding constraints:
# - minutes are mandatory, seconds are optional
# - sub-seconds must NOT be zero / no meaningless zeros
# - no hanging fraction dot
# - time in UTC (Z)
# - only dot is allowed for fractions
if asn1Spec is not None:
value = asn1Spec.clone(value)
numbers = value.asNumbers()
if self.PLUS_CHAR in numbers or self.MINUS_CHAR in numbers:
raise error.PyAsn1Error('Must be UTC time: %r' % value)
if numbers[-1] != self.Z_CHAR:
raise error.PyAsn1Error('Missing "Z" time zone specifier: %r' % value)
if self.COMMA_CHAR in numbers:
raise error.PyAsn1Error('Comma in fractions disallowed: %r' % value)
if self.DOT_CHAR in numbers:
isModified = False
numbers = list(numbers)
searchIndex = min(numbers.index(self.DOT_CHAR) + 4, len(numbers) - 1)
while numbers[searchIndex] != self.DOT_CHAR:
if numbers[searchIndex] == self.ZERO_CHAR:
del numbers[searchIndex]
isModified = True
searchIndex -= 1
searchIndex += 1
if searchIndex < len(numbers):
if numbers[searchIndex] == self.Z_CHAR:
# drop hanging comma
del numbers[searchIndex - 1]
isModified = True
if isModified:
value = value.clone(numbers)
if not self.MIN_LENGTH < len(numbers) < self.MAX_LENGTH:
raise error.PyAsn1Error('Length constraint violated: %r' % value)
options.update(maxChunkSize=1000)
return encoder.OctetStringEncoder.encodeValue(
self, value, asn1Spec, encodeFun, **options
)
class GeneralizedTimeEncoder(TimeEncoderMixIn, encoder.OctetStringEncoder):
MIN_LENGTH = 12
MAX_LENGTH = 20
class UTCTimeEncoder(TimeEncoderMixIn, encoder.OctetStringEncoder):
MIN_LENGTH = 10
MAX_LENGTH = 14
class SetOfEncoder(encoder.SequenceOfEncoder):
def encodeValue(self, value, asn1Spec, encodeFun, **options):
chunks = self._encodeComponents(
value, asn1Spec, encodeFun, **options)
# sort by serialised and padded components
if len(chunks) > 1:
zero = str2octs('\x00')
maxLen = max(map(len, chunks))
paddedChunks = [
(x.ljust(maxLen, zero), x) for x in chunks
]
paddedChunks.sort(key=lambda x: x[0])
chunks = [x[1] for x in paddedChunks]
return null.join(chunks), True, True
class SequenceOfEncoder(encoder.SequenceOfEncoder):
def encodeValue(self, value, asn1Spec, encodeFun, **options):
if options.get('ifNotEmpty', False) and not len(value):
return null, True, True
chunks = self._encodeComponents(
value, asn1Spec, encodeFun, **options)
return null.join(chunks), True, True
class SetEncoder(encoder.SequenceEncoder):
@staticmethod
def _componentSortKey(componentAndType):
"""Sort SET components by tag
Sort regardless of the Choice value (static sort)
"""
component, asn1Spec = componentAndType
if asn1Spec is None:
asn1Spec = component
if asn1Spec.typeId == univ.Choice.typeId and not asn1Spec.tagSet:
if asn1Spec.tagSet:
return asn1Spec.tagSet
else:
return asn1Spec.componentType.minTagSet
else:
return asn1Spec.tagSet
def encodeValue(self, value, asn1Spec, encodeFun, **options):
substrate = null
comps = []
compsMap = {}
if asn1Spec is None:
# instance of ASN.1 schema
inconsistency = value.isInconsistent
if inconsistency:
raise inconsistency
namedTypes = value.componentType
for idx, component in enumerate(value.values()):
if namedTypes:
namedType = namedTypes[idx]
if namedType.isOptional and not component.isValue:
continue
if namedType.isDefaulted and component == namedType.asn1Object:
continue
compsMap[id(component)] = namedType
else:
compsMap[id(component)] = None
comps.append((component, asn1Spec))
else:
# bare Python value + ASN.1 schema
for idx, namedType in enumerate(asn1Spec.componentType.namedTypes):
try:
component = value[namedType.name]
except KeyError:
raise error.PyAsn1Error('Component name "%s" not found in %r' % (namedType.name, value))
if namedType.isOptional and namedType.name not in value:
continue
if namedType.isDefaulted and component == namedType.asn1Object:
continue
compsMap[id(component)] = namedType
comps.append((component, asn1Spec[idx]))
for comp, compType in sorted(comps, key=self._componentSortKey):
namedType = compsMap[id(comp)]
if namedType:
options.update(ifNotEmpty=namedType.isOptional)
chunk = encodeFun(comp, compType, **options)
# wrap open type blob if needed
if namedType and namedType.openType:
wrapType = namedType.asn1Object
if wrapType.tagSet and not wrapType.isSameTypeWith(comp):
chunk = encodeFun(chunk, wrapType, **options)
substrate += chunk
return substrate, True, True
class SequenceEncoder(encoder.SequenceEncoder):
omitEmptyOptionals = True
tagMap = encoder.tagMap.copy()
tagMap.update({
univ.Boolean.tagSet: BooleanEncoder(),
univ.Real.tagSet: RealEncoder(),
useful.GeneralizedTime.tagSet: GeneralizedTimeEncoder(),
useful.UTCTime.tagSet: UTCTimeEncoder(),
# Sequence & Set have same tags as SequenceOf & SetOf
univ.SetOf.tagSet: SetOfEncoder(),
univ.Sequence.typeId: SequenceEncoder()
})
typeMap = encoder.typeMap.copy()
typeMap.update({
univ.Boolean.typeId: BooleanEncoder(),
univ.Real.typeId: RealEncoder(),
useful.GeneralizedTime.typeId: GeneralizedTimeEncoder(),
useful.UTCTime.typeId: UTCTimeEncoder(),
# Sequence & Set have same tags as SequenceOf & SetOf
univ.Set.typeId: SetEncoder(),
univ.SetOf.typeId: SetOfEncoder(),
univ.Sequence.typeId: SequenceEncoder(),
univ.SequenceOf.typeId: SequenceOfEncoder()
})
class Encoder(encoder.Encoder):
fixedDefLengthMode = False
fixedChunkSize = 1000
#: Turns ASN.1 object into CER octet stream.
#:
#: Takes any ASN.1 object (e.g. :py:class:`~pyasn1.type.base.PyAsn1Item` derivative)
#: walks all its components recursively and produces a CER octet stream.
#:
#: Parameters
#: ----------
#: value: either a Python or pyasn1 object (e.g. :py:class:`~pyasn1.type.base.PyAsn1Item` derivative)
#: A Python or pyasn1 object to encode. If Python object is given, `asnSpec`
#: parameter is required to guide the encoding process.
#:
#: Keyword Args
#: ------------
#: asn1Spec:
#: Optional ASN.1 schema or value object e.g. :py:class:`~pyasn1.type.base.PyAsn1Item` derivative
#:
#: Returns
#: -------
#: : :py:class:`bytes` (Python 3) or :py:class:`str` (Python 2)
#: Given ASN.1 object encoded into BER octet-stream
#:
#: Raises
#: ------
#: ~pyasn1.error.PyAsn1Error
#: On encoding errors
#:
#: Examples
#: --------
#: Encode Python value into CER with ASN.1 schema
#:
#: .. code-block:: pycon
#:
#: >>> seq = SequenceOf(componentType=Integer())
#: >>> encode([1, 2, 3], asn1Spec=seq)
#: b'0\x80\x02\x01\x01\x02\x01\x02\x02\x01\x03\x00\x00'
#:
#: Encode ASN.1 value object into CER
#:
#: .. code-block:: pycon
#:
#: >>> seq = SequenceOf(componentType=Integer())
#: >>> seq.extend([1, 2, 3])
#: >>> encode(seq)
#: b'0\x80\x02\x01\x01\x02\x01\x02\x02\x01\x03\x00\x00'
#:
encode = Encoder(tagMap, typeMap)
# EncoderFactory queries class instance and builds a map of tags -> encoders
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