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- #
- # This file is part of pyasn1 software.
- #
- # Copyright (c) 2005-2018, Ilya Etingof <etingof@gmail.com>
- # License: http://snmplabs.com/pyasn1/license.html
- #
- from pyasn1 import debug
- from pyasn1 import error
- from pyasn1.codec.ber import eoo
- from pyasn1.compat.integer import from_bytes
- from pyasn1.compat.octets import oct2int, octs2ints, ints2octs, null
- from pyasn1.type import base
- from pyasn1.type import char
- from pyasn1.type import tag
- from pyasn1.type import tagmap
- from pyasn1.type import univ
- from pyasn1.type import useful
-
- __all__ = ['decode']
-
- noValue = base.noValue
-
-
- class AbstractDecoder(object):
- protoComponent = None
-
- def valueDecoder(self, substrate, asn1Spec,
- tagSet=None, length=None, state=None,
- decodeFun=None, substrateFun=None,
- **options):
- raise error.PyAsn1Error('Decoder not implemented for %s' % (tagSet,))
-
- def indefLenValueDecoder(self, substrate, asn1Spec,
- tagSet=None, length=None, state=None,
- decodeFun=None, substrateFun=None,
- **options):
- raise error.PyAsn1Error('Indefinite length mode decoder not implemented for %s' % (tagSet,))
-
-
- class AbstractSimpleDecoder(AbstractDecoder):
- @staticmethod
- def substrateCollector(asn1Object, substrate, length):
- return substrate[:length], substrate[length:]
-
- def _createComponent(self, asn1Spec, tagSet, value, **options):
- if options.get('native'):
- return value
- elif asn1Spec is None:
- return self.protoComponent.clone(value, tagSet=tagSet)
- elif value is noValue:
- return asn1Spec
- else:
- return asn1Spec.clone(value)
-
-
- class ExplicitTagDecoder(AbstractSimpleDecoder):
- protoComponent = univ.Any('')
-
- def valueDecoder(self, substrate, asn1Spec,
- tagSet=None, length=None, state=None,
- decodeFun=None, substrateFun=None,
- **options):
- if substrateFun:
- return substrateFun(
- self._createComponent(asn1Spec, tagSet, '', **options),
- substrate, length
- )
-
- head, tail = substrate[:length], substrate[length:]
-
- value, _ = decodeFun(head, asn1Spec, tagSet, length, **options)
-
- return value, tail
-
- def indefLenValueDecoder(self, substrate, asn1Spec,
- tagSet=None, length=None, state=None,
- decodeFun=None, substrateFun=None,
- **options):
- if substrateFun:
- return substrateFun(
- self._createComponent(asn1Spec, tagSet, '', **options),
- substrate, length
- )
-
- value, substrate = decodeFun(substrate, asn1Spec, tagSet, length, **options)
-
- eooMarker, substrate = decodeFun(substrate, allowEoo=True, **options)
-
- if eooMarker is eoo.endOfOctets:
- return value, substrate
- else:
- raise error.PyAsn1Error('Missing end-of-octets terminator')
-
-
- explicitTagDecoder = ExplicitTagDecoder()
-
-
- class IntegerDecoder(AbstractSimpleDecoder):
- protoComponent = univ.Integer(0)
-
- def valueDecoder(self, substrate, asn1Spec,
- tagSet=None, length=None, state=None,
- decodeFun=None, substrateFun=None,
- **options):
-
- if tagSet[0].tagFormat != tag.tagFormatSimple:
- raise error.PyAsn1Error('Simple tag format expected')
-
- head, tail = substrate[:length], substrate[length:]
-
- if not head:
- return self._createComponent(asn1Spec, tagSet, 0, **options), tail
-
- value = from_bytes(head, signed=True)
-
- return self._createComponent(asn1Spec, tagSet, value, **options), tail
-
-
- class BooleanDecoder(IntegerDecoder):
- protoComponent = univ.Boolean(0)
-
- def _createComponent(self, asn1Spec, tagSet, value, **options):
- return IntegerDecoder._createComponent(self, asn1Spec, tagSet, value and 1 or 0, **options)
-
-
- class BitStringDecoder(AbstractSimpleDecoder):
- protoComponent = univ.BitString(())
- supportConstructedForm = True
-
- def valueDecoder(self, substrate, asn1Spec,
- tagSet=None, length=None, state=None,
- decodeFun=None, substrateFun=None,
- **options):
- head, tail = substrate[:length], substrate[length:]
-
- if substrateFun:
- return substrateFun(self._createComponent(asn1Spec, tagSet, noValue, **options),
- substrate, length)
-
- if not head:
- raise error.PyAsn1Error('Empty BIT STRING substrate')
-
- if tagSet[0].tagFormat == tag.tagFormatSimple: # XXX what tag to check?
-
- trailingBits = oct2int(head[0])
- if trailingBits > 7:
- raise error.PyAsn1Error(
- 'Trailing bits overflow %s' % trailingBits
- )
-
- value = self.protoComponent.fromOctetString(head[1:], internalFormat=True, padding=trailingBits)
-
- return self._createComponent(asn1Spec, tagSet, value, **options), tail
-
- if not self.supportConstructedForm:
- raise error.PyAsn1Error('Constructed encoding form prohibited at %s' % self.__class__.__name__)
-
- # All inner fragments are of the same type, treat them as octet string
- substrateFun = self.substrateCollector
-
- bitString = self.protoComponent.fromOctetString(null, internalFormat=True)
-
- while head:
- component, head = decodeFun(head, self.protoComponent,
- substrateFun=substrateFun, **options)
-
- trailingBits = oct2int(component[0])
- if trailingBits > 7:
- raise error.PyAsn1Error(
- 'Trailing bits overflow %s' % trailingBits
- )
-
- bitString = self.protoComponent.fromOctetString(
- component[1:], internalFormat=True,
- prepend=bitString, padding=trailingBits
- )
-
- return self._createComponent(asn1Spec, tagSet, bitString, **options), tail
-
- def indefLenValueDecoder(self, substrate, asn1Spec,
- tagSet=None, length=None, state=None,
- decodeFun=None, substrateFun=None,
- **options):
-
- if substrateFun:
- return substrateFun(self._createComponent(asn1Spec, tagSet, noValue, **options), substrate, length)
-
- # All inner fragments are of the same type, treat them as octet string
- substrateFun = self.substrateCollector
-
- bitString = self.protoComponent.fromOctetString(null, internalFormat=True)
-
- while substrate:
- component, substrate = decodeFun(substrate, self.protoComponent,
- substrateFun=substrateFun,
- allowEoo=True, **options)
- if component is eoo.endOfOctets:
- break
-
- trailingBits = oct2int(component[0])
- if trailingBits > 7:
- raise error.PyAsn1Error(
- 'Trailing bits overflow %s' % trailingBits
- )
-
- bitString = self.protoComponent.fromOctetString(
- component[1:], internalFormat=True,
- prepend=bitString, padding=trailingBits
- )
-
- else:
- raise error.SubstrateUnderrunError('No EOO seen before substrate ends')
-
- return self._createComponent(asn1Spec, tagSet, bitString, **options), substrate
-
-
- class OctetStringDecoder(AbstractSimpleDecoder):
- protoComponent = univ.OctetString('')
- supportConstructedForm = True
-
- def valueDecoder(self, substrate, asn1Spec,
- tagSet=None, length=None, state=None,
- decodeFun=None, substrateFun=None,
- **options):
- head, tail = substrate[:length], substrate[length:]
-
- if substrateFun:
- return substrateFun(self._createComponent(asn1Spec, tagSet, noValue, **options),
- substrate, length)
-
- if tagSet[0].tagFormat == tag.tagFormatSimple: # XXX what tag to check?
- return self._createComponent(asn1Spec, tagSet, head, **options), tail
-
- if not self.supportConstructedForm:
- raise error.PyAsn1Error('Constructed encoding form prohibited at %s' % self.__class__.__name__)
-
- # All inner fragments are of the same type, treat them as octet string
- substrateFun = self.substrateCollector
-
- header = null
-
- while head:
- component, head = decodeFun(head, self.protoComponent,
- substrateFun=substrateFun,
- **options)
- header += component
-
- return self._createComponent(asn1Spec, tagSet, header, **options), tail
-
- def indefLenValueDecoder(self, substrate, asn1Spec,
- tagSet=None, length=None, state=None,
- decodeFun=None, substrateFun=None,
- **options):
- if substrateFun and substrateFun is not self.substrateCollector:
- asn1Object = self._createComponent(asn1Spec, tagSet, noValue, **options)
- return substrateFun(asn1Object, substrate, length)
-
- # All inner fragments are of the same type, treat them as octet string
- substrateFun = self.substrateCollector
-
- header = null
-
- while substrate:
- component, substrate = decodeFun(substrate,
- self.protoComponent,
- substrateFun=substrateFun,
- allowEoo=True, **options)
- if component is eoo.endOfOctets:
- break
- header += component
- else:
- raise error.SubstrateUnderrunError(
- 'No EOO seen before substrate ends'
- )
-
- return self._createComponent(asn1Spec, tagSet, header, **options), substrate
-
-
- class NullDecoder(AbstractSimpleDecoder):
- protoComponent = univ.Null('')
-
- def valueDecoder(self, substrate, asn1Spec,
- tagSet=None, length=None, state=None,
- decodeFun=None, substrateFun=None,
- **options):
-
- if tagSet[0].tagFormat != tag.tagFormatSimple:
- raise error.PyAsn1Error('Simple tag format expected')
-
- head, tail = substrate[:length], substrate[length:]
-
- component = self._createComponent(asn1Spec, tagSet, '', **options)
-
- if head:
- raise error.PyAsn1Error('Unexpected %d-octet substrate for Null' % length)
-
- return component, tail
-
-
- class ObjectIdentifierDecoder(AbstractSimpleDecoder):
- protoComponent = univ.ObjectIdentifier(())
-
- def valueDecoder(self, substrate, asn1Spec,
- tagSet=None, length=None, state=None,
- decodeFun=None, substrateFun=None,
- **options):
- if tagSet[0].tagFormat != tag.tagFormatSimple:
- raise error.PyAsn1Error('Simple tag format expected')
-
- head, tail = substrate[:length], substrate[length:]
- if not head:
- raise error.PyAsn1Error('Empty substrate')
-
- head = octs2ints(head)
-
- oid = ()
- index = 0
- substrateLen = len(head)
- while index < substrateLen:
- subId = head[index]
- index += 1
- if subId < 128:
- oid += (subId,)
- elif subId > 128:
- # Construct subid from a number of octets
- nextSubId = subId
- subId = 0
- while nextSubId >= 128:
- subId = (subId << 7) + (nextSubId & 0x7F)
- if index >= substrateLen:
- raise error.SubstrateUnderrunError(
- 'Short substrate for sub-OID past %s' % (oid,)
- )
- nextSubId = head[index]
- index += 1
- oid += ((subId << 7) + nextSubId,)
- elif subId == 128:
- # ASN.1 spec forbids leading zeros (0x80) in OID
- # encoding, tolerating it opens a vulnerability. See
- # https://www.esat.kuleuven.be/cosic/publications/article-1432.pdf
- # page 7
- raise error.PyAsn1Error('Invalid octet 0x80 in OID encoding')
-
- # Decode two leading arcs
- if 0 <= oid[0] <= 39:
- oid = (0,) + oid
- elif 40 <= oid[0] <= 79:
- oid = (1, oid[0] - 40) + oid[1:]
- elif oid[0] >= 80:
- oid = (2, oid[0] - 80) + oid[1:]
- else:
- raise error.PyAsn1Error('Malformed first OID octet: %s' % head[0])
-
- return self._createComponent(asn1Spec, tagSet, oid, **options), tail
-
-
- class RealDecoder(AbstractSimpleDecoder):
- protoComponent = univ.Real()
-
- def valueDecoder(self, substrate, asn1Spec,
- tagSet=None, length=None, state=None,
- decodeFun=None, substrateFun=None,
- **options):
- if tagSet[0].tagFormat != tag.tagFormatSimple:
- raise error.PyAsn1Error('Simple tag format expected')
-
- head, tail = substrate[:length], substrate[length:]
-
- if not head:
- return self._createComponent(asn1Spec, tagSet, 0.0, **options), tail
-
- fo = oct2int(head[0])
- head = head[1:]
- if fo & 0x80: # binary encoding
- if not head:
- raise error.PyAsn1Error("Incomplete floating-point value")
- n = (fo & 0x03) + 1
- if n == 4:
- n = oct2int(head[0])
- head = head[1:]
- eo, head = head[:n], head[n:]
- if not eo or not head:
- raise error.PyAsn1Error('Real exponent screwed')
- e = oct2int(eo[0]) & 0x80 and -1 or 0
- while eo: # exponent
- e <<= 8
- e |= oct2int(eo[0])
- eo = eo[1:]
- b = fo >> 4 & 0x03 # base bits
- if b > 2:
- raise error.PyAsn1Error('Illegal Real base')
- if b == 1: # encbase = 8
- e *= 3
- elif b == 2: # encbase = 16
- e *= 4
- p = 0
- while head: # value
- p <<= 8
- p |= oct2int(head[0])
- head = head[1:]
- if fo & 0x40: # sign bit
- p = -p
- sf = fo >> 2 & 0x03 # scale bits
- p *= 2 ** sf
- value = (p, 2, e)
- elif fo & 0x40: # infinite value
- value = fo & 0x01 and '-inf' or 'inf'
- elif fo & 0xc0 == 0: # character encoding
- if not head:
- raise error.PyAsn1Error("Incomplete floating-point value")
- try:
- if fo & 0x3 == 0x1: # NR1
- value = (int(head), 10, 0)
- elif fo & 0x3 == 0x2: # NR2
- value = float(head)
- elif fo & 0x3 == 0x3: # NR3
- value = float(head)
- else:
- raise error.SubstrateUnderrunError(
- 'Unknown NR (tag %s)' % fo
- )
- except ValueError:
- raise error.SubstrateUnderrunError(
- 'Bad character Real syntax'
- )
- else:
- raise error.SubstrateUnderrunError(
- 'Unknown encoding (tag %s)' % fo
- )
- return self._createComponent(asn1Spec, tagSet, value, **options), tail
-
-
- class AbstractConstructedDecoder(AbstractDecoder):
- protoComponent = None
-
-
- class UniversalConstructedTypeDecoder(AbstractConstructedDecoder):
- protoRecordComponent = None
- protoSequenceComponent = None
-
- def _getComponentTagMap(self, asn1Object, idx):
- raise NotImplementedError()
-
- def _getComponentPositionByType(self, asn1Object, tagSet, idx):
- raise NotImplementedError()
-
- def _decodeComponents(self, substrate, tagSet=None, decodeFun=None, **options):
- components = []
- componentTypes = set()
- while substrate:
- component, substrate = decodeFun(substrate, **options)
- if component is eoo.endOfOctets:
- break
- components.append(component)
- componentTypes.add(component.tagSet)
-
- # Now we have to guess is it SEQUENCE/SET or SEQUENCE OF/SET OF
- # The heuristics is:
- # * 1+ components of different types -> likely SEQUENCE/SET
- # * otherwise -> likely SEQUENCE OF/SET OF
- if len(componentTypes) > 1:
- protoComponent = self.protoRecordComponent
- else:
- protoComponent = self.protoSequenceComponent
-
- asn1Object = protoComponent.clone(
- # construct tagSet from base tag from prototype ASN.1 object
- # and additional tags recovered from the substrate
- tagSet=tag.TagSet(protoComponent.tagSet.baseTag, *tagSet.superTags)
- )
-
- for idx, component in enumerate(components):
- asn1Object.setComponentByPosition(
- idx, component,
- verifyConstraints=False,
- matchTags=False, matchConstraints=False
- )
-
- return asn1Object, substrate
-
- def valueDecoder(self, substrate, asn1Spec,
- tagSet=None, length=None, state=None,
- decodeFun=None, substrateFun=None,
- **options):
- if tagSet[0].tagFormat != tag.tagFormatConstructed:
- raise error.PyAsn1Error('Constructed tag format expected')
-
- head, tail = substrate[:length], substrate[length:]
-
- if substrateFun is not None:
- if asn1Spec is not None:
- asn1Object = asn1Spec.clone()
- elif self.protoComponent is not None:
- asn1Object = self.protoComponent.clone(tagSet=tagSet)
- else:
- asn1Object = self.protoRecordComponent, self.protoSequenceComponent
-
- return substrateFun(asn1Object, substrate, length)
-
- if asn1Spec is None:
- asn1Object, trailing = self._decodeComponents(
- head, tagSet=tagSet, decodeFun=decodeFun, **options
- )
- if trailing:
- raise error.PyAsn1Error('Unused trailing %d octets encountered' % len(trailing))
- return asn1Object, tail
-
- asn1Object = asn1Spec.clone()
-
- if asn1Spec.typeId in (univ.Sequence.typeId, univ.Set.typeId):
-
- namedTypes = asn1Spec.componentType
-
- isSetType = asn1Spec.typeId == univ.Set.typeId
- isDeterministic = not isSetType and not namedTypes.hasOptionalOrDefault
-
- seenIndices = set()
- idx = 0
- while head:
- if not namedTypes:
- componentType = None
- elif isSetType:
- componentType = namedTypes.tagMapUnique
- else:
- try:
- if isDeterministic:
- componentType = namedTypes[idx].asn1Object
- elif namedTypes[idx].isOptional or namedTypes[idx].isDefaulted:
- componentType = namedTypes.getTagMapNearPosition(idx)
- else:
- componentType = namedTypes[idx].asn1Object
- except IndexError:
- raise error.PyAsn1Error(
- 'Excessive components decoded at %r' % (asn1Spec,)
- )
-
- component, head = decodeFun(head, componentType, **options)
-
- if not isDeterministic and namedTypes:
- if isSetType:
- idx = namedTypes.getPositionByType(component.effectiveTagSet)
- elif namedTypes[idx].isOptional or namedTypes[idx].isDefaulted:
- idx = namedTypes.getPositionNearType(component.effectiveTagSet, idx)
-
- asn1Object.setComponentByPosition(
- idx, component,
- verifyConstraints=False,
- matchTags=False, matchConstraints=False
- )
-
- seenIndices.add(idx)
- idx += 1
-
- if namedTypes:
- if not namedTypes.requiredComponents.issubset(seenIndices):
- raise error.PyAsn1Error('ASN.1 object %s has uninitialized components' % asn1Object.__class__.__name__)
-
- if namedTypes.hasOpenTypes:
-
- openTypes = options.get('openTypes', {})
-
- if openTypes or options.get('decodeOpenTypes', False):
-
- for idx, namedType in enumerate(namedTypes.namedTypes):
- if not namedType.openType:
- continue
-
- if namedType.isOptional and not asn1Object.getComponentByPosition(idx).isValue:
- continue
-
- governingValue = asn1Object.getComponentByName(
- namedType.openType.name
- )
-
- try:
- openType = openTypes[governingValue]
-
- except KeyError:
-
- try:
- openType = namedType.openType[governingValue]
-
- except KeyError:
- continue
-
- component, rest = decodeFun(
- asn1Object.getComponentByPosition(idx).asOctets(),
- asn1Spec=openType
- )
-
- asn1Object.setComponentByPosition(idx, component)
-
- else:
- asn1Object.verifySizeSpec()
-
- else:
- asn1Object = asn1Spec.clone()
-
- componentType = asn1Spec.componentType
-
- idx = 0
-
- while head:
- component, head = decodeFun(head, componentType, **options)
- asn1Object.setComponentByPosition(
- idx, component,
- verifyConstraints=False,
- matchTags=False, matchConstraints=False
- )
- idx += 1
-
- return asn1Object, tail
-
- def indefLenValueDecoder(self, substrate, asn1Spec,
- tagSet=None, length=None, state=None,
- decodeFun=None, substrateFun=None,
- **options):
- if tagSet[0].tagFormat != tag.tagFormatConstructed:
- raise error.PyAsn1Error('Constructed tag format expected')
-
- if substrateFun is not None:
- if asn1Spec is not None:
- asn1Object = asn1Spec.clone()
- elif self.protoComponent is not None:
- asn1Object = self.protoComponent.clone(tagSet=tagSet)
- else:
- asn1Object = self.protoRecordComponent, self.protoSequenceComponent
-
- return substrateFun(asn1Object, substrate, length)
-
- if asn1Spec is None:
- return self._decodeComponents(
- substrate, tagSet=tagSet, decodeFun=decodeFun, allowEoo=True, **options
- )
-
- asn1Object = asn1Spec.clone()
-
- if asn1Spec.typeId in (univ.Sequence.typeId, univ.Set.typeId):
-
- namedTypes = asn1Object.componentType
-
- isSetType = asn1Object.typeId == univ.Set.typeId
- isDeterministic = not isSetType and not namedTypes.hasOptionalOrDefault
-
- seenIndices = set()
- idx = 0
- while substrate:
- if len(namedTypes) <= idx:
- asn1Spec = None
- elif isSetType:
- asn1Spec = namedTypes.tagMapUnique
- else:
- try:
- if isDeterministic:
- asn1Spec = namedTypes[idx].asn1Object
- elif namedTypes[idx].isOptional or namedTypes[idx].isDefaulted:
- asn1Spec = namedTypes.getTagMapNearPosition(idx)
- else:
- asn1Spec = namedTypes[idx].asn1Object
- except IndexError:
- raise error.PyAsn1Error(
- 'Excessive components decoded at %r' % (asn1Object,)
- )
-
- component, substrate = decodeFun(substrate, asn1Spec, allowEoo=True, **options)
- if component is eoo.endOfOctets:
- break
-
- if not isDeterministic and namedTypes:
- if isSetType:
- idx = namedTypes.getPositionByType(component.effectiveTagSet)
- elif namedTypes[idx].isOptional or namedTypes[idx].isDefaulted:
- idx = namedTypes.getPositionNearType(component.effectiveTagSet, idx)
-
- asn1Object.setComponentByPosition(
- idx, component,
- verifyConstraints=False,
- matchTags=False, matchConstraints=False
- )
-
- seenIndices.add(idx)
- idx += 1
-
- else:
- raise error.SubstrateUnderrunError(
- 'No EOO seen before substrate ends'
- )
-
- if namedTypes:
- if not namedTypes.requiredComponents.issubset(seenIndices):
- raise error.PyAsn1Error('ASN.1 object %s has uninitialized components' % asn1Object.__class__.__name__)
-
- if namedTypes.hasOpenTypes:
-
- openTypes = options.get('openTypes', None)
-
- if openTypes or options.get('decodeOpenTypes', False):
-
- for idx, namedType in enumerate(namedTypes.namedTypes):
- if not namedType.openType:
- continue
-
- if namedType.isOptional and not asn1Object.getComponentByPosition(idx).isValue:
- continue
-
- governingValue = asn1Object.getComponentByName(
- namedType.openType.name
- )
-
- try:
- openType = openTypes[governingValue]
-
- except KeyError:
-
- try:
- openType = namedType.openType[governingValue]
-
- except KeyError:
- continue
-
- component, rest = decodeFun(
- asn1Object.getComponentByPosition(idx).asOctets(),
- asn1Spec=openType, allowEoo=True
- )
-
- if component is not eoo.endOfOctets:
- asn1Object.setComponentByPosition(idx, component)
-
- else:
- asn1Object.verifySizeSpec()
-
- else:
- asn1Object = asn1Spec.clone()
-
- componentType = asn1Spec.componentType
-
- idx = 0
-
- while substrate:
- component, substrate = decodeFun(substrate, componentType, allowEoo=True, **options)
-
- if component is eoo.endOfOctets:
- break
-
- asn1Object.setComponentByPosition(
- idx, component,
- verifyConstraints=False,
- matchTags=False, matchConstraints=False
- )
- idx += 1
- else:
- raise error.SubstrateUnderrunError(
- 'No EOO seen before substrate ends'
- )
-
- return asn1Object, substrate
-
-
- class SequenceOrSequenceOfDecoder(UniversalConstructedTypeDecoder):
- protoRecordComponent = univ.Sequence()
- protoSequenceComponent = univ.SequenceOf()
-
-
- class SequenceDecoder(SequenceOrSequenceOfDecoder):
- protoComponent = univ.Sequence()
-
-
- class SequenceOfDecoder(SequenceOrSequenceOfDecoder):
- protoComponent = univ.SequenceOf()
-
-
- class SetOrSetOfDecoder(UniversalConstructedTypeDecoder):
- protoRecordComponent = univ.Set()
- protoSequenceComponent = univ.SetOf()
-
-
- class SetDecoder(SetOrSetOfDecoder):
- protoComponent = univ.Set()
-
-
-
- class SetOfDecoder(SetOrSetOfDecoder):
- protoComponent = univ.SetOf()
-
-
- class ChoiceDecoder(AbstractConstructedDecoder):
- protoComponent = univ.Choice()
-
- def valueDecoder(self, substrate, asn1Spec,
- tagSet=None, length=None, state=None,
- decodeFun=None, substrateFun=None,
- **options):
- head, tail = substrate[:length], substrate[length:]
-
- if asn1Spec is None:
- asn1Object = self.protoComponent.clone(tagSet=tagSet)
- else:
- asn1Object = asn1Spec.clone()
-
- if substrateFun:
- return substrateFun(asn1Object, substrate, length)
-
- if asn1Object.tagSet == tagSet: # explicitly tagged Choice
- component, head = decodeFun(
- head, asn1Object.componentTagMap, **options
- )
-
- else:
- component, head = decodeFun(
- head, asn1Object.componentTagMap,
- tagSet, length, state, **options
- )
-
- effectiveTagSet = component.effectiveTagSet
-
- asn1Object.setComponentByType(
- effectiveTagSet, component,
- verifyConstraints=False,
- matchTags=False, matchConstraints=False,
- innerFlag=False
- )
-
- return asn1Object, tail
-
- def indefLenValueDecoder(self, substrate, asn1Spec,
- tagSet=None, length=None, state=None,
- decodeFun=None, substrateFun=None,
- **options):
- if asn1Spec is None:
- asn1Object = self.protoComponent.clone(tagSet=tagSet)
- else:
- asn1Object = asn1Spec.clone()
-
- if substrateFun:
- return substrateFun(asn1Object, substrate, length)
-
- if asn1Object.tagSet == tagSet: # explicitly tagged Choice
- component, substrate = decodeFun(
- substrate, asn1Object.componentType.tagMapUnique, **options
- )
- # eat up EOO marker
- eooMarker, substrate = decodeFun(
- substrate, allowEoo=True, **options
- )
- if eooMarker is not eoo.endOfOctets:
- raise error.PyAsn1Error('No EOO seen before substrate ends')
-
- else:
- component, substrate = decodeFun(
- substrate, asn1Object.componentType.tagMapUnique,
- tagSet, length, state, **options
- )
-
- effectiveTagSet = component.effectiveTagSet
-
- asn1Object.setComponentByType(
- effectiveTagSet, component,
- verifyConstraints=False,
- matchTags=False, matchConstraints=False,
- innerFlag=False
- )
-
- return asn1Object, substrate
-
-
- class AnyDecoder(AbstractSimpleDecoder):
- protoComponent = univ.Any()
-
- def valueDecoder(self, substrate, asn1Spec,
- tagSet=None, length=None, state=None,
- decodeFun=None, substrateFun=None,
- **options):
- if asn1Spec is None or asn1Spec is not None and tagSet != asn1Spec.tagSet:
- fullSubstrate = options['fullSubstrate']
-
- # untagged Any container, recover inner header substrate
- length += len(fullSubstrate) - len(substrate)
- substrate = fullSubstrate
-
- if substrateFun:
- return substrateFun(self._createComponent(asn1Spec, tagSet, noValue, **options),
- substrate, length)
-
- head, tail = substrate[:length], substrate[length:]
-
- return self._createComponent(asn1Spec, tagSet, head, **options), tail
-
- def indefLenValueDecoder(self, substrate, asn1Spec,
- tagSet=None, length=None, state=None,
- decodeFun=None, substrateFun=None,
- **options):
- if asn1Spec is not None and tagSet == asn1Spec.tagSet:
- # tagged Any type -- consume header substrate
- header = null
- else:
- fullSubstrate = options['fullSubstrate']
-
- # untagged Any, recover header substrate
- header = fullSubstrate[:-len(substrate)]
-
- # Any components do not inherit initial tag
- asn1Spec = self.protoComponent
-
- if substrateFun and substrateFun is not self.substrateCollector:
- asn1Object = self._createComponent(asn1Spec, tagSet, noValue, **options)
- return substrateFun(asn1Object, header + substrate, length + len(header))
-
- # All inner fragments are of the same type, treat them as octet string
- substrateFun = self.substrateCollector
-
- while substrate:
- component, substrate = decodeFun(substrate, asn1Spec,
- substrateFun=substrateFun,
- allowEoo=True, **options)
- if component is eoo.endOfOctets:
- break
- header += component
- else:
- raise error.SubstrateUnderrunError(
- 'No EOO seen before substrate ends'
- )
- if substrateFun:
- return header, substrate
- else:
- return self._createComponent(asn1Spec, tagSet, header, **options), substrate
-
-
- # character string types
- class UTF8StringDecoder(OctetStringDecoder):
- protoComponent = char.UTF8String()
-
-
- class NumericStringDecoder(OctetStringDecoder):
- protoComponent = char.NumericString()
-
-
- class PrintableStringDecoder(OctetStringDecoder):
- protoComponent = char.PrintableString()
-
-
- class TeletexStringDecoder(OctetStringDecoder):
- protoComponent = char.TeletexString()
-
-
- class VideotexStringDecoder(OctetStringDecoder):
- protoComponent = char.VideotexString()
-
-
- class IA5StringDecoder(OctetStringDecoder):
- protoComponent = char.IA5String()
-
-
- class GraphicStringDecoder(OctetStringDecoder):
- protoComponent = char.GraphicString()
-
-
- class VisibleStringDecoder(OctetStringDecoder):
- protoComponent = char.VisibleString()
-
-
- class GeneralStringDecoder(OctetStringDecoder):
- protoComponent = char.GeneralString()
-
-
- class UniversalStringDecoder(OctetStringDecoder):
- protoComponent = char.UniversalString()
-
-
- class BMPStringDecoder(OctetStringDecoder):
- protoComponent = char.BMPString()
-
-
- # "useful" types
- class ObjectDescriptorDecoder(OctetStringDecoder):
- protoComponent = useful.ObjectDescriptor()
-
-
- class GeneralizedTimeDecoder(OctetStringDecoder):
- protoComponent = useful.GeneralizedTime()
-
-
- class UTCTimeDecoder(OctetStringDecoder):
- protoComponent = useful.UTCTime()
-
-
- tagMap = {
- univ.Integer.tagSet: IntegerDecoder(),
- univ.Boolean.tagSet: BooleanDecoder(),
- univ.BitString.tagSet: BitStringDecoder(),
- univ.OctetString.tagSet: OctetStringDecoder(),
- univ.Null.tagSet: NullDecoder(),
- univ.ObjectIdentifier.tagSet: ObjectIdentifierDecoder(),
- univ.Enumerated.tagSet: IntegerDecoder(),
- univ.Real.tagSet: RealDecoder(),
- univ.Sequence.tagSet: SequenceOrSequenceOfDecoder(), # conflicts with SequenceOf
- univ.Set.tagSet: SetOrSetOfDecoder(), # conflicts with SetOf
- univ.Choice.tagSet: ChoiceDecoder(), # conflicts with Any
- # character string types
- char.UTF8String.tagSet: UTF8StringDecoder(),
- char.NumericString.tagSet: NumericStringDecoder(),
- char.PrintableString.tagSet: PrintableStringDecoder(),
- char.TeletexString.tagSet: TeletexStringDecoder(),
- char.VideotexString.tagSet: VideotexStringDecoder(),
- char.IA5String.tagSet: IA5StringDecoder(),
- char.GraphicString.tagSet: GraphicStringDecoder(),
- char.VisibleString.tagSet: VisibleStringDecoder(),
- char.GeneralString.tagSet: GeneralStringDecoder(),
- char.UniversalString.tagSet: UniversalStringDecoder(),
- char.BMPString.tagSet: BMPStringDecoder(),
- # useful types
- useful.ObjectDescriptor.tagSet: ObjectDescriptorDecoder(),
- useful.GeneralizedTime.tagSet: GeneralizedTimeDecoder(),
- useful.UTCTime.tagSet: UTCTimeDecoder()
- }
-
- # Type-to-codec map for ambiguous ASN.1 types
- typeMap = {
- univ.Set.typeId: SetDecoder(),
- univ.SetOf.typeId: SetOfDecoder(),
- univ.Sequence.typeId: SequenceDecoder(),
- univ.SequenceOf.typeId: SequenceOfDecoder(),
- univ.Choice.typeId: ChoiceDecoder(),
- univ.Any.typeId: AnyDecoder()
- }
-
- # Put in non-ambiguous types for faster codec lookup
- for typeDecoder in tagMap.values():
- if typeDecoder.protoComponent is not None:
- typeId = typeDecoder.protoComponent.__class__.typeId
- if typeId is not None and typeId not in typeMap:
- typeMap[typeId] = typeDecoder
-
-
- (stDecodeTag,
- stDecodeLength,
- stGetValueDecoder,
- stGetValueDecoderByAsn1Spec,
- stGetValueDecoderByTag,
- stTryAsExplicitTag,
- stDecodeValue,
- stDumpRawValue,
- stErrorCondition,
- stStop) = [x for x in range(10)]
-
-
- class Decoder(object):
- defaultErrorState = stErrorCondition
- # defaultErrorState = stDumpRawValue
- defaultRawDecoder = AnyDecoder()
- supportIndefLength = True
-
- # noinspection PyDefaultArgument
- def __init__(self, tagMap, typeMap={}):
- self.__tagMap = tagMap
- self.__typeMap = typeMap
- # Tag & TagSet objects caches
- self.__tagCache = {}
- self.__tagSetCache = {}
- self.__eooSentinel = ints2octs((0, 0))
-
- def __call__(self, substrate, asn1Spec=None,
- tagSet=None, length=None, state=stDecodeTag,
- decodeFun=None, substrateFun=None,
- **options):
-
- if debug.logger & debug.flagDecoder:
- logger = debug.logger
- else:
- logger = None
-
- if logger:
- logger('decoder called at scope %s with state %d, working with up to %d octets of substrate: %s' % (debug.scope, state, len(substrate), debug.hexdump(substrate)))
-
- allowEoo = options.pop('allowEoo', False)
-
- # Look for end-of-octets sentinel
- if allowEoo and self.supportIndefLength:
- if substrate[:2] == self.__eooSentinel:
- if logger:
- logger('end-of-octets sentinel found')
- return eoo.endOfOctets, substrate[2:]
-
- value = noValue
-
- tagMap = self.__tagMap
- typeMap = self.__typeMap
- tagCache = self.__tagCache
- tagSetCache = self.__tagSetCache
-
- fullSubstrate = substrate
-
- while state is not stStop:
- if state is stDecodeTag:
- if not substrate:
- raise error.SubstrateUnderrunError(
- 'Short octet stream on tag decoding'
- )
- # Decode tag
- isShortTag = True
- firstOctet = substrate[0]
- substrate = substrate[1:]
- try:
- lastTag = tagCache[firstOctet]
- except KeyError:
- integerTag = oct2int(firstOctet)
- tagClass = integerTag & 0xC0
- tagFormat = integerTag & 0x20
- tagId = integerTag & 0x1F
- if tagId == 0x1F:
- isShortTag = False
- lengthOctetIdx = 0
- tagId = 0
- try:
- while True:
- integerTag = oct2int(substrate[lengthOctetIdx])
- lengthOctetIdx += 1
- tagId <<= 7
- tagId |= (integerTag & 0x7F)
- if not integerTag & 0x80:
- break
- substrate = substrate[lengthOctetIdx:]
- except IndexError:
- raise error.SubstrateUnderrunError(
- 'Short octet stream on long tag decoding'
- )
- lastTag = tag.Tag(
- tagClass=tagClass, tagFormat=tagFormat, tagId=tagId
- )
- if isShortTag:
- # cache short tags
- tagCache[firstOctet] = lastTag
- if tagSet is None:
- if isShortTag:
- try:
- tagSet = tagSetCache[firstOctet]
- except KeyError:
- # base tag not recovered
- tagSet = tag.TagSet((), lastTag)
- tagSetCache[firstOctet] = tagSet
- else:
- tagSet = tag.TagSet((), lastTag)
- else:
- tagSet = lastTag + tagSet
- state = stDecodeLength
- if logger:
- logger('tag decoded into %s, decoding length' % tagSet)
- if state is stDecodeLength:
- # Decode length
- if not substrate:
- raise error.SubstrateUnderrunError(
- 'Short octet stream on length decoding'
- )
- firstOctet = oct2int(substrate[0])
- if firstOctet < 128:
- size = 1
- length = firstOctet
- elif firstOctet > 128:
- size = firstOctet & 0x7F
- # encoded in size bytes
- encodedLength = octs2ints(substrate[1:size + 1])
- # missing check on maximum size, which shouldn't be a
- # problem, we can handle more than is possible
- if len(encodedLength) != size:
- raise error.SubstrateUnderrunError(
- '%s<%s at %s' % (size, len(encodedLength), tagSet)
- )
- length = 0
- for lengthOctet in encodedLength:
- length <<= 8
- length |= lengthOctet
- size += 1
- else:
- size = 1
- length = -1
-
- substrate = substrate[size:]
- if length == -1:
- if not self.supportIndefLength:
- raise error.PyAsn1Error('Indefinite length encoding not supported by this codec')
- else:
- if len(substrate) < length:
- raise error.SubstrateUnderrunError('%d-octet short' % (length - len(substrate)))
- state = stGetValueDecoder
- if logger:
- logger('value length decoded into %d, payload substrate is: %s' % (length, debug.hexdump(length == -1 and substrate or substrate[:length])))
- if state is stGetValueDecoder:
- if asn1Spec is None:
- state = stGetValueDecoderByTag
- else:
- state = stGetValueDecoderByAsn1Spec
- #
- # There're two ways of creating subtypes in ASN.1 what influences
- # decoder operation. These methods are:
- # 1) Either base types used in or no IMPLICIT tagging has been
- # applied on subtyping.
- # 2) Subtype syntax drops base type information (by means of
- # IMPLICIT tagging.
- # The first case allows for complete tag recovery from substrate
- # while the second one requires original ASN.1 type spec for
- # decoding.
- #
- # In either case a set of tags (tagSet) is coming from substrate
- # in an incremental, tag-by-tag fashion (this is the case of
- # EXPLICIT tag which is most basic). Outermost tag comes first
- # from the wire.
- #
- if state is stGetValueDecoderByTag:
- try:
- concreteDecoder = tagMap[tagSet]
- except KeyError:
- concreteDecoder = None
- if concreteDecoder:
- state = stDecodeValue
- else:
- try:
- concreteDecoder = tagMap[tagSet[:1]]
- except KeyError:
- concreteDecoder = None
- if concreteDecoder:
- state = stDecodeValue
- else:
- state = stTryAsExplicitTag
- if logger:
- logger('codec %s chosen by a built-in type, decoding %s' % (concreteDecoder and concreteDecoder.__class__.__name__ or "<none>", state is stDecodeValue and 'value' or 'as explicit tag'))
- debug.scope.push(concreteDecoder is None and '?' or concreteDecoder.protoComponent.__class__.__name__)
- if state is stGetValueDecoderByAsn1Spec:
- if asn1Spec.__class__ is tagmap.TagMap:
- try:
- chosenSpec = asn1Spec[tagSet]
- except KeyError:
- chosenSpec = None
- if logger:
- logger('candidate ASN.1 spec is a map of:')
- for firstOctet, v in asn1Spec.presentTypes.items():
- logger(' %s -> %s' % (firstOctet, v.__class__.__name__))
- if asn1Spec.skipTypes:
- logger('but neither of: ')
- for firstOctet, v in asn1Spec.skipTypes.items():
- logger(' %s -> %s' % (firstOctet, v.__class__.__name__))
- logger('new candidate ASN.1 spec is %s, chosen by %s' % (chosenSpec is None and '<none>' or chosenSpec.prettyPrintType(), tagSet))
- elif tagSet == asn1Spec.tagSet or tagSet in asn1Spec.tagMap:
- chosenSpec = asn1Spec
- if logger:
- logger('candidate ASN.1 spec is %s' % asn1Spec.__class__.__name__)
- else:
- chosenSpec = None
-
- if chosenSpec is not None:
- try:
- # ambiguous type or just faster codec lookup
- concreteDecoder = typeMap[chosenSpec.typeId]
- if logger:
- logger('value decoder chosen for an ambiguous type by type ID %s' % (chosenSpec.typeId,))
- except KeyError:
- # use base type for codec lookup to recover untagged types
- baseTagSet = tag.TagSet(chosenSpec.tagSet.baseTag, chosenSpec.tagSet.baseTag)
- try:
- # base type or tagged subtype
- concreteDecoder = tagMap[baseTagSet]
- if logger:
- logger('value decoder chosen by base %s' % (baseTagSet,))
- except KeyError:
- concreteDecoder = None
- if concreteDecoder:
- asn1Spec = chosenSpec
- state = stDecodeValue
- else:
- state = stTryAsExplicitTag
- else:
- concreteDecoder = None
- state = stTryAsExplicitTag
- if logger:
- logger('codec %s chosen by ASN.1 spec, decoding %s' % (state is stDecodeValue and concreteDecoder.__class__.__name__ or "<none>", state is stDecodeValue and 'value' or 'as explicit tag'))
- debug.scope.push(chosenSpec is None and '?' or chosenSpec.__class__.__name__)
- if state is stDecodeValue:
- if not options.get('recursiveFlag', True) and not substrateFun: # deprecate this
- substrateFun = lambda a, b, c: (a, b[:c])
-
- options.update(fullSubstrate=fullSubstrate)
-
- if length == -1: # indef length
- value, substrate = concreteDecoder.indefLenValueDecoder(
- substrate, asn1Spec,
- tagSet, length, stGetValueDecoder,
- self, substrateFun,
- **options
- )
- else:
- value, substrate = concreteDecoder.valueDecoder(
- substrate, asn1Spec,
- tagSet, length, stGetValueDecoder,
- self, substrateFun,
- **options
- )
-
- if logger:
- logger('codec %s yields type %s, value:\n%s\n...remaining substrate is: %s' % (concreteDecoder.__class__.__name__, value.__class__.__name__, isinstance(value, base.Asn1Item) and value.prettyPrint() or value, substrate and debug.hexdump(substrate) or '<none>'))
-
- state = stStop
- break
- if state is stTryAsExplicitTag:
- if tagSet and tagSet[0].tagFormat == tag.tagFormatConstructed and tagSet[0].tagClass != tag.tagClassUniversal:
- # Assume explicit tagging
- concreteDecoder = explicitTagDecoder
- state = stDecodeValue
- else:
- concreteDecoder = None
- state = self.defaultErrorState
- if logger:
- logger('codec %s chosen, decoding %s' % (concreteDecoder and concreteDecoder.__class__.__name__ or "<none>", state is stDecodeValue and 'value' or 'as failure'))
- if state is stDumpRawValue:
- concreteDecoder = self.defaultRawDecoder
- if logger:
- logger('codec %s chosen, decoding value' % concreteDecoder.__class__.__name__)
- state = stDecodeValue
- if state is stErrorCondition:
- raise error.PyAsn1Error(
- '%s not in asn1Spec: %r' % (tagSet, asn1Spec)
- )
- if logger:
- debug.scope.pop()
- logger('decoder left scope %s, call completed' % debug.scope)
- return value, substrate
-
-
- #: Turns BER octet stream into an ASN.1 object.
- #:
- #: Takes BER octet-stream and decode it into an ASN.1 object
- #: (e.g. :py:class:`~pyasn1.type.base.PyAsn1Item` derivative) which
- #: may be a scalar or an arbitrary nested structure.
- #:
- #: Parameters
- #: ----------
- #: substrate: :py:class:`bytes` (Python 3) or :py:class:`str` (Python 2)
- #: BER octet-stream
- #:
- #: Keyword Args
- #: ------------
- #: asn1Spec: any pyasn1 type object e.g. :py:class:`~pyasn1.type.base.PyAsn1Item` derivative
- #: A pyasn1 type object to act as a template guiding the decoder. Depending on the ASN.1 structure
- #: being decoded, *asn1Spec* may or may not be required. Most common reason for
- #: it to require is that ASN.1 structure is encoded in *IMPLICIT* tagging mode.
- #:
- #: Returns
- #: -------
- #: : :py:class:`tuple`
- #: A tuple of pyasn1 object recovered from BER substrate (:py:class:`~pyasn1.type.base.PyAsn1Item` derivative)
- #: and the unprocessed trailing portion of the *substrate* (may be empty)
- #:
- #: Raises
- #: ------
- #: :py:class:`~pyasn1.error.PyAsn1Error`
- #: On decoding errors
- #:
- #: Examples
- #: --------
- #: Decode BER serialisation without ASN.1 schema
- #:
- #: .. code-block:: pycon
- #:
- #: >>> s, _ = decode(b'0\t\x02\x01\x01\x02\x01\x02\x02\x01\x03')
- #: >>> str(s)
- #: SequenceOf:
- #: 1 2 3
- #:
- #: Decode BER serialisation with ASN.1 schema
- #:
- #: .. code-block:: pycon
- #:
- #: >>> seq = SequenceOf(componentType=Integer())
- #: >>> s, _ = decode(b'0\t\x02\x01\x01\x02\x01\x02\x02\x01\x03', asn1Spec=seq)
- #: >>> str(s)
- #: SequenceOf:
- #: 1 2 3
- #:
- decode = Decoder(tagMap, typeMap)
-
- # XXX
- # non-recursive decoding; return position rather than substrate
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