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1683 lines
58 KiB
1683 lines
58 KiB
#
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# This file is part of pyasn1 software.
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#
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# Copyright (c) 2005-2019, Ilya Etingof <etingof@gmail.com>
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# License: http://snmplabs.com/pyasn1/license.html
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#
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from pyasn1 import debug
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from pyasn1 import error
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from pyasn1.codec.ber import eoo
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from pyasn1.compat.integer import from_bytes
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from pyasn1.compat.octets import oct2int, octs2ints, ints2octs, null
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from pyasn1.type import base
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from pyasn1.type import char
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from pyasn1.type import tag
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from pyasn1.type import tagmap
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from pyasn1.type import univ
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from pyasn1.type import useful
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__all__ = ['decode']
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LOG = debug.registerLoggee(__name__, flags=debug.DEBUG_DECODER)
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noValue = base.noValue
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class AbstractDecoder(object):
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protoComponent = None
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def valueDecoder(self, substrate, asn1Spec,
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tagSet=None, length=None, state=None,
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decodeFun=None, substrateFun=None,
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**options):
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raise error.PyAsn1Error('Decoder not implemented for %s' % (tagSet,))
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def indefLenValueDecoder(self, substrate, asn1Spec,
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tagSet=None, length=None, state=None,
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decodeFun=None, substrateFun=None,
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**options):
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raise error.PyAsn1Error('Indefinite length mode decoder not implemented for %s' % (tagSet,))
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class AbstractSimpleDecoder(AbstractDecoder):
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@staticmethod
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def substrateCollector(asn1Object, substrate, length):
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return substrate[:length], substrate[length:]
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def _createComponent(self, asn1Spec, tagSet, value, **options):
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if options.get('native'):
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return value
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elif asn1Spec is None:
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return self.protoComponent.clone(value, tagSet=tagSet)
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elif value is noValue:
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return asn1Spec
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else:
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return asn1Spec.clone(value)
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class ExplicitTagDecoder(AbstractSimpleDecoder):
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protoComponent = univ.Any('')
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def valueDecoder(self, substrate, asn1Spec,
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tagSet=None, length=None, state=None,
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decodeFun=None, substrateFun=None,
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**options):
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if substrateFun:
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return substrateFun(
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self._createComponent(asn1Spec, tagSet, '', **options),
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substrate, length
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)
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head, tail = substrate[:length], substrate[length:]
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value, _ = decodeFun(head, asn1Spec, tagSet, length, **options)
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if LOG:
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LOG('explicit tag container carries %d octets of trailing payload '
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'(will be lost!): %s' % (len(_), debug.hexdump(_)))
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return value, tail
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def indefLenValueDecoder(self, substrate, asn1Spec,
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tagSet=None, length=None, state=None,
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decodeFun=None, substrateFun=None,
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**options):
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if substrateFun:
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return substrateFun(
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self._createComponent(asn1Spec, tagSet, '', **options),
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substrate, length
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)
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value, substrate = decodeFun(substrate, asn1Spec, tagSet, length, **options)
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eooMarker, substrate = decodeFun(substrate, allowEoo=True, **options)
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if eooMarker is eoo.endOfOctets:
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return value, substrate
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else:
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raise error.PyAsn1Error('Missing end-of-octets terminator')
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explicitTagDecoder = ExplicitTagDecoder()
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class IntegerDecoder(AbstractSimpleDecoder):
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protoComponent = univ.Integer(0)
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def valueDecoder(self, substrate, asn1Spec,
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tagSet=None, length=None, state=None,
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decodeFun=None, substrateFun=None,
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**options):
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if tagSet[0].tagFormat != tag.tagFormatSimple:
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raise error.PyAsn1Error('Simple tag format expected')
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head, tail = substrate[:length], substrate[length:]
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if not head:
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return self._createComponent(asn1Spec, tagSet, 0, **options), tail
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value = from_bytes(head, signed=True)
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return self._createComponent(asn1Spec, tagSet, value, **options), tail
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class BooleanDecoder(IntegerDecoder):
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protoComponent = univ.Boolean(0)
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def _createComponent(self, asn1Spec, tagSet, value, **options):
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return IntegerDecoder._createComponent(
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self, asn1Spec, tagSet, value and 1 or 0, **options)
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class BitStringDecoder(AbstractSimpleDecoder):
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protoComponent = univ.BitString(())
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supportConstructedForm = True
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def valueDecoder(self, substrate, asn1Spec,
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tagSet=None, length=None, state=None,
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decodeFun=None, substrateFun=None,
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**options):
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head, tail = substrate[:length], substrate[length:]
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if substrateFun:
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return substrateFun(self._createComponent(
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asn1Spec, tagSet, noValue, **options), substrate, length)
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if not head:
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raise error.PyAsn1Error('Empty BIT STRING substrate')
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if tagSet[0].tagFormat == tag.tagFormatSimple: # XXX what tag to check?
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trailingBits = oct2int(head[0])
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if trailingBits > 7:
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raise error.PyAsn1Error(
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'Trailing bits overflow %s' % trailingBits
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)
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value = self.protoComponent.fromOctetString(
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head[1:], internalFormat=True, padding=trailingBits)
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return self._createComponent(asn1Spec, tagSet, value, **options), tail
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if not self.supportConstructedForm:
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raise error.PyAsn1Error('Constructed encoding form prohibited '
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'at %s' % self.__class__.__name__)
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if LOG:
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LOG('assembling constructed serialization')
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# All inner fragments are of the same type, treat them as octet string
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substrateFun = self.substrateCollector
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bitString = self.protoComponent.fromOctetString(null, internalFormat=True)
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while head:
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component, head = decodeFun(head, self.protoComponent,
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substrateFun=substrateFun, **options)
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trailingBits = oct2int(component[0])
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if trailingBits > 7:
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raise error.PyAsn1Error(
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'Trailing bits overflow %s' % trailingBits
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)
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bitString = self.protoComponent.fromOctetString(
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component[1:], internalFormat=True,
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prepend=bitString, padding=trailingBits
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)
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return self._createComponent(asn1Spec, tagSet, bitString, **options), tail
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def indefLenValueDecoder(self, substrate, asn1Spec,
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tagSet=None, length=None, state=None,
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decodeFun=None, substrateFun=None,
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**options):
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if substrateFun:
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return substrateFun(self._createComponent(asn1Spec, tagSet, noValue, **options), substrate, length)
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# All inner fragments are of the same type, treat them as octet string
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substrateFun = self.substrateCollector
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bitString = self.protoComponent.fromOctetString(null, internalFormat=True)
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while substrate:
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component, substrate = decodeFun(substrate, self.protoComponent,
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substrateFun=substrateFun,
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allowEoo=True, **options)
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if component is eoo.endOfOctets:
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break
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trailingBits = oct2int(component[0])
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if trailingBits > 7:
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raise error.PyAsn1Error(
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'Trailing bits overflow %s' % trailingBits
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)
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bitString = self.protoComponent.fromOctetString(
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component[1:], internalFormat=True,
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prepend=bitString, padding=trailingBits
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)
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else:
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raise error.SubstrateUnderrunError('No EOO seen before substrate ends')
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return self._createComponent(asn1Spec, tagSet, bitString, **options), substrate
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class OctetStringDecoder(AbstractSimpleDecoder):
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protoComponent = univ.OctetString('')
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supportConstructedForm = True
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def valueDecoder(self, substrate, asn1Spec,
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tagSet=None, length=None, state=None,
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decodeFun=None, substrateFun=None,
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**options):
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head, tail = substrate[:length], substrate[length:]
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if substrateFun:
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return substrateFun(self._createComponent(asn1Spec, tagSet, noValue, **options),
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substrate, length)
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if tagSet[0].tagFormat == tag.tagFormatSimple: # XXX what tag to check?
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return self._createComponent(asn1Spec, tagSet, head, **options), tail
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if not self.supportConstructedForm:
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raise error.PyAsn1Error('Constructed encoding form prohibited at %s' % self.__class__.__name__)
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if LOG:
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LOG('assembling constructed serialization')
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# All inner fragments are of the same type, treat them as octet string
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substrateFun = self.substrateCollector
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header = null
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while head:
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component, head = decodeFun(head, self.protoComponent,
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substrateFun=substrateFun,
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**options)
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header += component
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return self._createComponent(asn1Spec, tagSet, header, **options), tail
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def indefLenValueDecoder(self, substrate, asn1Spec,
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tagSet=None, length=None, state=None,
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decodeFun=None, substrateFun=None,
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**options):
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if substrateFun and substrateFun is not self.substrateCollector:
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asn1Object = self._createComponent(asn1Spec, tagSet, noValue, **options)
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return substrateFun(asn1Object, substrate, length)
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# All inner fragments are of the same type, treat them as octet string
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substrateFun = self.substrateCollector
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header = null
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while substrate:
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component, substrate = decodeFun(substrate,
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self.protoComponent,
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substrateFun=substrateFun,
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allowEoo=True, **options)
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if component is eoo.endOfOctets:
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break
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header += component
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else:
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raise error.SubstrateUnderrunError(
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'No EOO seen before substrate ends'
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)
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return self._createComponent(asn1Spec, tagSet, header, **options), substrate
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class NullDecoder(AbstractSimpleDecoder):
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protoComponent = univ.Null('')
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def valueDecoder(self, substrate, asn1Spec,
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tagSet=None, length=None, state=None,
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decodeFun=None, substrateFun=None,
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**options):
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if tagSet[0].tagFormat != tag.tagFormatSimple:
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raise error.PyAsn1Error('Simple tag format expected')
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head, tail = substrate[:length], substrate[length:]
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component = self._createComponent(asn1Spec, tagSet, '', **options)
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if head:
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raise error.PyAsn1Error('Unexpected %d-octet substrate for Null' % length)
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return component, tail
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class ObjectIdentifierDecoder(AbstractSimpleDecoder):
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protoComponent = univ.ObjectIdentifier(())
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def valueDecoder(self, substrate, asn1Spec,
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tagSet=None, length=None, state=None,
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decodeFun=None, substrateFun=None,
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**options):
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if tagSet[0].tagFormat != tag.tagFormatSimple:
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raise error.PyAsn1Error('Simple tag format expected')
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head, tail = substrate[:length], substrate[length:]
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if not head:
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raise error.PyAsn1Error('Empty substrate')
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head = octs2ints(head)
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oid = ()
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index = 0
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substrateLen = len(head)
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while index < substrateLen:
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subId = head[index]
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index += 1
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if subId < 128:
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oid += (subId,)
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elif subId > 128:
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# Construct subid from a number of octets
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nextSubId = subId
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subId = 0
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while nextSubId >= 128:
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subId = (subId << 7) + (nextSubId & 0x7F)
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if index >= substrateLen:
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raise error.SubstrateUnderrunError(
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'Short substrate for sub-OID past %s' % (oid,)
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)
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nextSubId = head[index]
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index += 1
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oid += ((subId << 7) + nextSubId,)
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elif subId == 128:
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# ASN.1 spec forbids leading zeros (0x80) in OID
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# encoding, tolerating it opens a vulnerability. See
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# https://www.esat.kuleuven.be/cosic/publications/article-1432.pdf
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# page 7
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raise error.PyAsn1Error('Invalid octet 0x80 in OID encoding')
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# Decode two leading arcs
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if 0 <= oid[0] <= 39:
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oid = (0,) + oid
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elif 40 <= oid[0] <= 79:
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oid = (1, oid[0] - 40) + oid[1:]
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elif oid[0] >= 80:
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oid = (2, oid[0] - 80) + oid[1:]
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else:
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raise error.PyAsn1Error('Malformed first OID octet: %s' % head[0])
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return self._createComponent(asn1Spec, tagSet, oid, **options), tail
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class RealDecoder(AbstractSimpleDecoder):
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protoComponent = univ.Real()
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def valueDecoder(self, substrate, asn1Spec,
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tagSet=None, length=None, state=None,
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decodeFun=None, substrateFun=None,
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**options):
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if tagSet[0].tagFormat != tag.tagFormatSimple:
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raise error.PyAsn1Error('Simple tag format expected')
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head, tail = substrate[:length], substrate[length:]
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if not head:
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return self._createComponent(asn1Spec, tagSet, 0.0, **options), tail
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fo = oct2int(head[0])
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head = head[1:]
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if fo & 0x80: # binary encoding
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if not head:
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raise error.PyAsn1Error("Incomplete floating-point value")
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if LOG:
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LOG('decoding binary encoded REAL')
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n = (fo & 0x03) + 1
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if n == 4:
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n = oct2int(head[0])
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head = head[1:]
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eo, head = head[:n], head[n:]
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if not eo or not head:
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raise error.PyAsn1Error('Real exponent screwed')
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e = oct2int(eo[0]) & 0x80 and -1 or 0
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while eo: # exponent
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e <<= 8
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e |= oct2int(eo[0])
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eo = eo[1:]
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b = fo >> 4 & 0x03 # base bits
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if b > 2:
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raise error.PyAsn1Error('Illegal Real base')
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if b == 1: # encbase = 8
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e *= 3
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elif b == 2: # encbase = 16
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e *= 4
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p = 0
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while head: # value
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p <<= 8
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p |= oct2int(head[0])
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head = head[1:]
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if fo & 0x40: # sign bit
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p = -p
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sf = fo >> 2 & 0x03 # scale bits
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p *= 2 ** sf
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value = (p, 2, e)
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elif fo & 0x40: # infinite value
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if LOG:
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LOG('decoding infinite REAL')
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value = fo & 0x01 and '-inf' or 'inf'
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elif fo & 0xc0 == 0: # character encoding
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if not head:
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raise error.PyAsn1Error("Incomplete floating-point value")
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if LOG:
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LOG('decoding character encoded REAL')
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try:
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if fo & 0x3 == 0x1: # NR1
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value = (int(head), 10, 0)
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elif fo & 0x3 == 0x2: # NR2
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value = float(head)
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elif fo & 0x3 == 0x3: # NR3
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value = float(head)
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else:
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raise error.SubstrateUnderrunError(
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'Unknown NR (tag %s)' % fo
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)
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except ValueError:
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raise error.SubstrateUnderrunError(
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'Bad character Real syntax'
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)
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else:
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raise error.SubstrateUnderrunError(
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'Unknown encoding (tag %s)' % fo
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)
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return self._createComponent(asn1Spec, tagSet, value, **options), tail
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|
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class AbstractConstructedDecoder(AbstractDecoder):
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protoComponent = None
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class UniversalConstructedTypeDecoder(AbstractConstructedDecoder):
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protoRecordComponent = None
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protoSequenceComponent = None
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def _getComponentTagMap(self, asn1Object, idx):
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raise NotImplementedError()
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def _getComponentPositionByType(self, asn1Object, tagSet, idx):
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raise NotImplementedError()
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def _decodeComponents(self, substrate, tagSet=None, decodeFun=None, **options):
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components = []
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componentTypes = set()
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|
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while substrate:
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component, substrate = decodeFun(substrate, **options)
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if component is eoo.endOfOctets:
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break
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components.append(component)
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componentTypes.add(component.tagSet)
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|
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# Now we have to guess is it SEQUENCE/SET or SEQUENCE OF/SET OF
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# The heuristics is:
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# * 1+ components of different types -> likely SEQUENCE/SET
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# * otherwise -> likely SEQUENCE OF/SET OF
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if len(componentTypes) > 1:
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protoComponent = self.protoRecordComponent
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else:
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protoComponent = self.protoSequenceComponent
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asn1Object = protoComponent.clone(
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# construct tagSet from base tag from prototype ASN.1 object
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# and additional tags recovered from the substrate
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tagSet=tag.TagSet(protoComponent.tagSet.baseTag, *tagSet.superTags)
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)
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if LOG:
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LOG('guessed %r container type (pass `asn1Spec` to guide the '
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'decoder)' % asn1Object)
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for idx, component in enumerate(components):
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asn1Object.setComponentByPosition(
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idx, component,
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verifyConstraints=False,
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matchTags=False, matchConstraints=False
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)
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return asn1Object, substrate
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|
|
def valueDecoder(self, substrate, asn1Spec,
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tagSet=None, length=None, state=None,
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decodeFun=None, substrateFun=None,
|
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**options):
|
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if tagSet[0].tagFormat != tag.tagFormatConstructed:
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raise error.PyAsn1Error('Constructed tag format expected')
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|
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head, tail = substrate[:length], substrate[length:]
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|
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if substrateFun is not None:
|
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if asn1Spec is not None:
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asn1Object = asn1Spec.clone()
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|
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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:
|
|
if LOG:
|
|
LOG('Unused trailing %d octets encountered: %s' % (
|
|
len(trailing), debug.hexdump(trailing)))
|
|
|
|
return asn1Object, tail
|
|
|
|
asn1Object = asn1Spec.clone()
|
|
asn1Object.clear()
|
|
|
|
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
|
|
|
|
if LOG:
|
|
LOG('decoding %sdeterministic %s type %r chosen by type ID' % (
|
|
not isDeterministic and 'non-' or '', isSetType and 'SET' or '',
|
|
asn1Spec))
|
|
|
|
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 LOG:
|
|
LOG('seen component indices %s' % seenIndices)
|
|
|
|
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 LOG:
|
|
LOG('user-specified open types map:')
|
|
|
|
for k, v in openTypes.items():
|
|
LOG('%s -> %r' % (k, v))
|
|
|
|
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:
|
|
|
|
if LOG:
|
|
LOG('default open types map of component '
|
|
'"%s.%s" governed by component "%s.%s"'
|
|
':' % (asn1Object.__class__.__name__,
|
|
namedType.name,
|
|
asn1Object.__class__.__name__,
|
|
namedType.openType.name))
|
|
|
|
for k, v in namedType.openType.items():
|
|
LOG('%s -> %r' % (k, v))
|
|
|
|
try:
|
|
openType = namedType.openType[governingValue]
|
|
|
|
except KeyError:
|
|
if LOG:
|
|
LOG('failed to resolve open type by governing '
|
|
'value %r' % (governingValue,))
|
|
continue
|
|
|
|
if LOG:
|
|
LOG('resolved open type %r by governing '
|
|
'value %r' % (openType, governingValue))
|
|
|
|
containerValue = asn1Object.getComponentByPosition(idx)
|
|
|
|
if containerValue.typeId in (
|
|
univ.SetOf.typeId, univ.SequenceOf.typeId):
|
|
|
|
for pos, containerElement in enumerate(
|
|
containerValue):
|
|
|
|
component, rest = decodeFun(
|
|
containerValue[pos].asOctets(),
|
|
asn1Spec=openType, **options
|
|
)
|
|
|
|
containerValue[pos] = component
|
|
|
|
else:
|
|
component, rest = decodeFun(
|
|
asn1Object.getComponentByPosition(idx).asOctets(),
|
|
asn1Spec=openType, **options
|
|
)
|
|
|
|
asn1Object.setComponentByPosition(idx, component)
|
|
|
|
else:
|
|
inconsistency = asn1Object.isInconsistent
|
|
if inconsistency:
|
|
raise inconsistency
|
|
|
|
else:
|
|
asn1Object = asn1Spec.clone()
|
|
asn1Object.clear()
|
|
|
|
componentType = asn1Spec.componentType
|
|
|
|
if LOG:
|
|
LOG('decoding type %r chosen by given `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,
|
|
**dict(options, allowEoo=True)
|
|
)
|
|
|
|
asn1Object = asn1Spec.clone()
|
|
asn1Object.clear()
|
|
|
|
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
|
|
|
|
if LOG:
|
|
LOG('decoding %sdeterministic %s type %r chosen by type ID' % (
|
|
not isDeterministic and 'non-' or '', isSetType and 'SET' or '',
|
|
asn1Spec))
|
|
|
|
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 LOG:
|
|
LOG('seen component indices %s' % seenIndices)
|
|
|
|
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 LOG:
|
|
LOG('user-specified open types map:')
|
|
|
|
for k, v in openTypes.items():
|
|
LOG('%s -> %r' % (k, v))
|
|
|
|
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:
|
|
|
|
if LOG:
|
|
LOG('default open types map of component '
|
|
'"%s.%s" governed by component "%s.%s"'
|
|
':' % (asn1Object.__class__.__name__,
|
|
namedType.name,
|
|
asn1Object.__class__.__name__,
|
|
namedType.openType.name))
|
|
|
|
for k, v in namedType.openType.items():
|
|
LOG('%s -> %r' % (k, v))
|
|
|
|
try:
|
|
openType = namedType.openType[governingValue]
|
|
|
|
except KeyError:
|
|
if LOG:
|
|
LOG('failed to resolve open type by governing '
|
|
'value %r' % (governingValue,))
|
|
continue
|
|
|
|
if LOG:
|
|
LOG('resolved open type %r by governing '
|
|
'value %r' % (openType, governingValue))
|
|
|
|
containerValue = asn1Object.getComponentByPosition(idx)
|
|
|
|
if containerValue.typeId in (
|
|
univ.SetOf.typeId, univ.SequenceOf.typeId):
|
|
|
|
for pos, containerElement in enumerate(
|
|
containerValue):
|
|
|
|
component, rest = decodeFun(
|
|
containerValue[pos].asOctets(),
|
|
asn1Spec=openType, **dict(options, allowEoo=True)
|
|
)
|
|
|
|
containerValue[pos] = component
|
|
|
|
else:
|
|
component, rest = decodeFun(
|
|
asn1Object.getComponentByPosition(idx).asOctets(),
|
|
asn1Spec=openType, **dict(options, allowEoo=True)
|
|
)
|
|
|
|
if component is not eoo.endOfOctets:
|
|
asn1Object.setComponentByPosition(idx, component)
|
|
|
|
else:
|
|
inconsistency = asn1Object.isInconsistent
|
|
if inconsistency:
|
|
raise inconsistency
|
|
|
|
else:
|
|
asn1Object = asn1Spec.clone()
|
|
asn1Object.clear()
|
|
|
|
componentType = asn1Spec.componentType
|
|
|
|
if LOG:
|
|
LOG('decoding type %r chosen by given `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:
|
|
if LOG:
|
|
LOG('decoding %s as explicitly tagged CHOICE' % (tagSet,))
|
|
|
|
component, head = decodeFun(
|
|
head, asn1Object.componentTagMap, **options
|
|
)
|
|
|
|
else:
|
|
if LOG:
|
|
LOG('decoding %s as untagged CHOICE' % (tagSet,))
|
|
|
|
component, head = decodeFun(
|
|
head, asn1Object.componentTagMap,
|
|
tagSet, length, state, **options
|
|
)
|
|
|
|
effectiveTagSet = component.effectiveTagSet
|
|
|
|
if LOG:
|
|
LOG('decoded component %s, effective tag set %s' % (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:
|
|
if LOG:
|
|
LOG('decoding %s as explicitly tagged CHOICE' % (tagSet,))
|
|
|
|
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:
|
|
if LOG:
|
|
LOG('decoding %s as untagged CHOICE' % (tagSet,))
|
|
|
|
component, substrate = decodeFun(
|
|
substrate, asn1Object.componentType.tagMapUnique,
|
|
tagSet, length, state, **options
|
|
)
|
|
|
|
effectiveTagSet = component.effectiveTagSet
|
|
|
|
if LOG:
|
|
LOG('decoded component %s, effective tag set %s' % (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:
|
|
isUntagged = True
|
|
|
|
elif asn1Spec.__class__ is tagmap.TagMap:
|
|
isUntagged = tagSet not in asn1Spec.tagMap
|
|
|
|
else:
|
|
isUntagged = tagSet != asn1Spec.tagSet
|
|
|
|
if isUntagged:
|
|
fullSubstrate = options['fullSubstrate']
|
|
|
|
# untagged Any container, recover inner header substrate
|
|
length += len(fullSubstrate) - len(substrate)
|
|
substrate = fullSubstrate
|
|
|
|
if LOG:
|
|
LOG('decoding as untagged ANY, substrate %s' % debug.hexdump(substrate))
|
|
|
|
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 None:
|
|
isTagged = False
|
|
|
|
elif asn1Spec.__class__ is tagmap.TagMap:
|
|
isTagged = tagSet in asn1Spec.tagMap
|
|
|
|
else:
|
|
isTagged = tagSet == asn1Spec.tagSet
|
|
|
|
if isTagged:
|
|
# tagged Any type -- consume header substrate
|
|
header = null
|
|
|
|
if LOG:
|
|
LOG('decoding as tagged ANY')
|
|
|
|
else:
|
|
fullSubstrate = options['fullSubstrate']
|
|
|
|
# untagged Any, recover header substrate
|
|
header = fullSubstrate[:-len(substrate)]
|
|
|
|
if LOG:
|
|
LOG('decoding as untagged ANY, header substrate %s' % debug.hexdump(header))
|
|
|
|
# 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))
|
|
|
|
if LOG:
|
|
LOG('assembling constructed serialization')
|
|
|
|
# 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 LOG:
|
|
LOG('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 LOG:
|
|
LOG('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 LOG:
|
|
LOG('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 LOG:
|
|
LOG('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 LOG:
|
|
LOG('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 LOG:
|
|
LOG('candidate ASN.1 spec is a map of:')
|
|
|
|
for firstOctet, v in asn1Spec.presentTypes.items():
|
|
LOG(' %s -> %s' % (firstOctet, v.__class__.__name__))
|
|
|
|
if asn1Spec.skipTypes:
|
|
LOG('but neither of: ')
|
|
for firstOctet, v in asn1Spec.skipTypes.items():
|
|
LOG(' %s -> %s' % (firstOctet, v.__class__.__name__))
|
|
LOG('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 LOG:
|
|
LOG('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 LOG:
|
|
LOG('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 LOG:
|
|
LOG('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 LOG:
|
|
LOG('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 LOG:
|
|
LOG('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 LOG:
|
|
LOG('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 LOG:
|
|
LOG('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 LOG:
|
|
debug.scope.pop()
|
|
LOG('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
|
|
#: ------
|
|
#: ~pyasn1.error.PyAsn1Error, ~pyasn1.error.SubstrateUnderrunError
|
|
#: 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
|