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Edit File: encoder.py
# # 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