File: //opt/imunify360/venv/lib64/python3.11/site-packages/pyasn1/codec/ber/decoder.py
#
# This file is part of pyasn1 software.
#
# Copyright (c) 2005-2020, Ilya Etingof <etingof@gmail.com>
# License: https://pyasn1.readthedocs.io/en/latest/license.html
#
import io
import os
import sys
import warnings
from pyasn1 import debug
from pyasn1 import error
from pyasn1.codec.ber import eoo
from pyasn1.codec.streaming import asSeekableStream
from pyasn1.codec.streaming import isEndOfStream
from pyasn1.codec.streaming import peekIntoStream
from pyasn1.codec.streaming import readFromStream
from pyasn1.compat import _MISSING
from pyasn1.error import PyAsn1Error
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__ = ['StreamingDecoder', 'Decoder', 'decode']
LOG = debug.registerLoggee(__name__, flags=debug.DEBUG_DECODER)
noValue = base.noValue
SubstrateUnderrunError = error.SubstrateUnderrunError
class AbstractPayloadDecoder(object):
protoComponent = None
def valueDecoder(self, substrate, asn1Spec,
tagSet=None, length=None, state=None,
decodeFun=None, substrateFun=None,
**options):
"""Decode value with fixed byte length.
The decoder is allowed to consume as many bytes as necessary.
"""
raise error.PyAsn1Error('SingleItemDecoder not implemented for %s' % (tagSet,)) # TODO: Seems more like an NotImplementedError?
def indefLenValueDecoder(self, substrate, asn1Spec,
tagSet=None, length=None, state=None,
decodeFun=None, substrateFun=None,
**options):
"""Decode value with undefined length.
The decoder is allowed to consume as many bytes as necessary.
"""
raise error.PyAsn1Error('Indefinite length mode decoder not implemented for %s' % (tagSet,)) # TODO: Seems more like an NotImplementedError?
@staticmethod
def _passAsn1Object(asn1Object, options):
if 'asn1Object' not in options:
options['asn1Object'] = asn1Object
return options
class AbstractSimplePayloadDecoder(AbstractPayloadDecoder):
@staticmethod
def substrateCollector(asn1Object, substrate, length, options):
for chunk in readFromStream(substrate, length, options):
yield chunk
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 RawPayloadDecoder(AbstractSimplePayloadDecoder):
protoComponent = univ.Any('')
def valueDecoder(self, substrate, asn1Spec,
tagSet=None, length=None, state=None,
decodeFun=None, substrateFun=None,
**options):
if substrateFun:
asn1Object = self._createComponent(asn1Spec, tagSet, '', **options)
for chunk in substrateFun(asn1Object, substrate, length, options):
yield chunk
return
for value in decodeFun(substrate, asn1Spec, tagSet, length, **options):
yield value
def indefLenValueDecoder(self, substrate, asn1Spec,
tagSet=None, length=None, state=None,
decodeFun=None, substrateFun=None,
**options):
if substrateFun:
asn1Object = self._createComponent(asn1Spec, tagSet, '', **options)
for chunk in substrateFun(asn1Object, substrate, length, options):
yield chunk
return
while True:
for value in decodeFun(
substrate, asn1Spec, tagSet, length,
allowEoo=True, **options):
if value is eoo.endOfOctets:
return
yield value
rawPayloadDecoder = RawPayloadDecoder()
class IntegerPayloadDecoder(AbstractSimplePayloadDecoder):
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')
for chunk in readFromStream(substrate, length, options):
if isinstance(chunk, SubstrateUnderrunError):
yield chunk
if chunk:
value = int.from_bytes(bytes(chunk), 'big', signed=True)
else:
value = 0
yield self._createComponent(asn1Spec, tagSet, value, **options)
class BooleanPayloadDecoder(IntegerPayloadDecoder):
protoComponent = univ.Boolean(0)
def _createComponent(self, asn1Spec, tagSet, value, **options):
return IntegerPayloadDecoder._createComponent(
self, asn1Spec, tagSet, value and 1 or 0, **options)
class BitStringPayloadDecoder(AbstractSimplePayloadDecoder):
protoComponent = univ.BitString(())
supportConstructedForm = True
def valueDecoder(self, substrate, asn1Spec,
tagSet=None, length=None, state=None,
decodeFun=None, substrateFun=None,
**options):
if substrateFun:
asn1Object = self._createComponent(asn1Spec, tagSet, noValue, **options)
for chunk in substrateFun(asn1Object, substrate, length, options):
yield chunk
return
if not length:
raise error.PyAsn1Error('Empty BIT STRING substrate')
for chunk in isEndOfStream(substrate):
if isinstance(chunk, SubstrateUnderrunError):
yield chunk
if chunk:
raise error.PyAsn1Error('Empty BIT STRING substrate')
if tagSet[0].tagFormat == tag.tagFormatSimple: # XXX what tag to check?
for trailingBits in readFromStream(substrate, 1, options):
if isinstance(trailingBits, SubstrateUnderrunError):
yield trailingBits
trailingBits = ord(trailingBits)
if trailingBits > 7:
raise error.PyAsn1Error(
'Trailing bits overflow %s' % trailingBits
)
for chunk in readFromStream(substrate, length - 1, options):
if isinstance(chunk, SubstrateUnderrunError):
yield chunk
value = self.protoComponent.fromOctetString(
chunk, internalFormat=True, padding=trailingBits)
yield self._createComponent(asn1Spec, tagSet, value, **options)
return
if not self.supportConstructedForm:
raise error.PyAsn1Error('Constructed encoding form prohibited '
'at %s' % self.__class__.__name__)
if LOG:
LOG('assembling constructed serialization')
# All inner fragments are of the same type, treat them as octet string
substrateFun = self.substrateCollector
bitString = self.protoComponent.fromOctetString(b'', internalFormat=True)
current_position = substrate.tell()
while substrate.tell() - current_position < length:
for component in decodeFun(
substrate, self.protoComponent, substrateFun=substrateFun,
**options):
if isinstance(component, SubstrateUnderrunError):
yield component
trailingBits = 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
)
yield self._createComponent(asn1Spec, tagSet, bitString, **options)
def indefLenValueDecoder(self, substrate, asn1Spec,
tagSet=None, length=None, state=None,
decodeFun=None, substrateFun=None,
**options):
if substrateFun:
asn1Object = self._createComponent(asn1Spec, tagSet, noValue, **options)
for chunk in substrateFun(asn1Object, substrate, length, options):
yield chunk
return
# All inner fragments are of the same type, treat them as octet string
substrateFun = self.substrateCollector
bitString = self.protoComponent.fromOctetString(b'', internalFormat=True)
while True: # loop over fragments
for component in decodeFun(
substrate, self.protoComponent, substrateFun=substrateFun,
allowEoo=True, **options):
if component is eoo.endOfOctets:
break
if isinstance(component, SubstrateUnderrunError):
yield component
if component is eoo.endOfOctets:
break
trailingBits = 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
)
yield self._createComponent(asn1Spec, tagSet, bitString, **options)
class OctetStringPayloadDecoder(AbstractSimplePayloadDecoder):
protoComponent = univ.OctetString('')
supportConstructedForm = True
def valueDecoder(self, substrate, asn1Spec,
tagSet=None, length=None, state=None,
decodeFun=None, substrateFun=None,
**options):
if substrateFun:
asn1Object = self._createComponent(asn1Spec, tagSet, noValue, **options)
for chunk in substrateFun(asn1Object, substrate, length, options):
yield chunk
return
if tagSet[0].tagFormat == tag.tagFormatSimple: # XXX what tag to check?
for chunk in readFromStream(substrate, length, options):
if isinstance(chunk, SubstrateUnderrunError):
yield chunk
yield self._createComponent(asn1Spec, tagSet, chunk, **options)
return
if not self.supportConstructedForm:
raise error.PyAsn1Error('Constructed encoding form prohibited at %s' % self.__class__.__name__)
if LOG:
LOG('assembling constructed serialization')
# All inner fragments are of the same type, treat them as octet string
substrateFun = self.substrateCollector
header = b''
original_position = substrate.tell()
# head = popSubstream(substrate, length)
while substrate.tell() - original_position < length:
for component in decodeFun(
substrate, self.protoComponent, substrateFun=substrateFun,
**options):
if isinstance(component, SubstrateUnderrunError):
yield component
header += component
yield self._createComponent(asn1Spec, tagSet, header, **options)
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)
for chunk in substrateFun(asn1Object, substrate, length, options):
yield chunk
return
# All inner fragments are of the same type, treat them as octet string
substrateFun = self.substrateCollector
header = b''
while True: # loop over fragments
for component in decodeFun(
substrate, self.protoComponent, substrateFun=substrateFun,
allowEoo=True, **options):
if isinstance(component, SubstrateUnderrunError):
yield component
if component is eoo.endOfOctets:
break
if component is eoo.endOfOctets:
break
header += component
yield self._createComponent(asn1Spec, tagSet, header, **options)
class NullPayloadDecoder(AbstractSimplePayloadDecoder):
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')
for chunk in readFromStream(substrate, length, options):
if isinstance(chunk, SubstrateUnderrunError):
yield chunk
component = self._createComponent(asn1Spec, tagSet, '', **options)
if chunk:
raise error.PyAsn1Error('Unexpected %d-octet substrate for Null' % length)
yield component
class ObjectIdentifierPayloadDecoder(AbstractSimplePayloadDecoder):
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')
for chunk in readFromStream(substrate, length, options):
if isinstance(chunk, SubstrateUnderrunError):
yield chunk
if not chunk:
raise error.PyAsn1Error('Empty substrate')
oid = ()
index = 0
substrateLen = len(chunk)
while index < substrateLen:
subId = chunk[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 = chunk[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' % chunk[0])
yield self._createComponent(asn1Spec, tagSet, oid, **options)
class RelativeOIDPayloadDecoder(AbstractSimplePayloadDecoder):
protoComponent = univ.RelativeOID(())
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')
for chunk in readFromStream(substrate, length, options):
if isinstance(chunk, SubstrateUnderrunError):
yield chunk
if not chunk:
raise error.PyAsn1Error('Empty substrate')
reloid = ()
index = 0
substrateLen = len(chunk)
while index < substrateLen:
subId = chunk[index]
index += 1
if subId < 128:
reloid += (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' % (reloid,)
)
nextSubId = chunk[index]
index += 1
reloid += ((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 RELATIVE-OID encoding')
yield self._createComponent(asn1Spec, tagSet, reloid, **options)
class RealPayloadDecoder(AbstractSimplePayloadDecoder):
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')
for chunk in readFromStream(substrate, length, options):
if isinstance(chunk, SubstrateUnderrunError):
yield chunk
if not chunk:
yield self._createComponent(asn1Spec, tagSet, 0.0, **options)
return
fo = chunk[0]
chunk = chunk[1:]
if fo & 0x80: # binary encoding
if not chunk:
raise error.PyAsn1Error("Incomplete floating-point value")
if LOG:
LOG('decoding binary encoded REAL')
n = (fo & 0x03) + 1
if n == 4:
n = chunk[0]
chunk = chunk[1:]
eo, chunk = chunk[:n], chunk[n:]
if not eo or not chunk:
raise error.PyAsn1Error('Real exponent screwed')
e = eo[0] & 0x80 and -1 or 0
while eo: # exponent
e <<= 8
e |= 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 chunk: # value
p <<= 8
p |= chunk[0]
chunk = chunk[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
if LOG:
LOG('decoding infinite REAL')
value = fo & 0x01 and '-inf' or 'inf'
elif fo & 0xc0 == 0: # character encoding
if not chunk:
raise error.PyAsn1Error("Incomplete floating-point value")
if LOG:
LOG('decoding character encoded REAL')
try:
if fo & 0x3 == 0x1: # NR1
value = (int(chunk), 10, 0)
elif fo & 0x3 == 0x2: # NR2
value = float(chunk)
elif fo & 0x3 == 0x3: # NR3
value = float(chunk)
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
)
yield self._createComponent(asn1Spec, tagSet, value, **options)
class AbstractConstructedPayloadDecoder(AbstractPayloadDecoder):
protoComponent = None
class ConstructedPayloadDecoderBase(AbstractConstructedPayloadDecoder):
protoRecordComponent = None
protoSequenceComponent = None
def _getComponentTagMap(self, asn1Object, idx):
raise NotImplementedError
def _getComponentPositionByType(self, asn1Object, tagSet, idx):
raise NotImplementedError
def _decodeComponentsSchemaless(
self, substrate, tagSet=None, decodeFun=None,
length=None, **options):
asn1Object = None
components = []
componentTypes = set()
original_position = substrate.tell()
while length == -1 or substrate.tell() < original_position + length:
for component in decodeFun(substrate, **options):
if isinstance(component, SubstrateUnderrunError):
yield component
if length == -1 and 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)
)
if LOG:
LOG('guessed %r container type (pass `asn1Spec` to guide the '
'decoder)' % asn1Object)
for idx, component in enumerate(components):
asn1Object.setComponentByPosition(
idx, component,
verifyConstraints=False,
matchTags=False, matchConstraints=False
)
yield asn1Object
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')
original_position = substrate.tell()
if substrateFun:
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
for chunk in substrateFun(asn1Object, substrate, length, options):
yield chunk
return
if asn1Spec is None:
for asn1Object in self._decodeComponentsSchemaless(
substrate, tagSet=tagSet, decodeFun=decodeFun,
length=length, **options):
if isinstance(asn1Object, SubstrateUnderrunError):
yield asn1Object
if substrate.tell() < original_position + length:
if LOG:
for trailing in readFromStream(substrate, context=options):
if isinstance(trailing, SubstrateUnderrunError):
yield trailing
LOG('Unused trailing %d octets encountered: %s' % (
len(trailing), debug.hexdump(trailing)))
yield asn1Object
return
asn1Object = asn1Spec.clone()
asn1Object.clear()
options = self._passAsn1Object(asn1Object, options)
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 substrate.tell() - original_position < length:
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,)
)
for component in decodeFun(substrate, componentType, **options):
if isinstance(component, SubstrateUnderrunError):
yield component
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):
stream = asSeekableStream(containerValue[pos].asOctets())
for component in decodeFun(stream, asn1Spec=openType, **options):
if isinstance(component, SubstrateUnderrunError):
yield component
containerValue[pos] = component
else:
stream = asSeekableStream(asn1Object.getComponentByPosition(idx).asOctets())
for component in decodeFun(stream, asn1Spec=openType, **options):
if isinstance(component, SubstrateUnderrunError):
yield component
asn1Object.setComponentByPosition(idx, component)
else:
inconsistency = asn1Object.isInconsistent
if inconsistency:
raise error.PyAsn1Error(
f"ASN.1 object {asn1Object.__class__.__name__} is inconsistent")
else:
componentType = asn1Spec.componentType
if LOG:
LOG('decoding type %r chosen by given `asn1Spec`' % componentType)
idx = 0
while substrate.tell() - original_position < length:
for component in decodeFun(substrate, componentType, **options):
if isinstance(component, SubstrateUnderrunError):
yield component
asn1Object.setComponentByPosition(
idx, component,
verifyConstraints=False,
matchTags=False, matchConstraints=False
)
idx += 1
yield asn1Object
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
for chunk in substrateFun(asn1Object, substrate, length, options):
yield chunk
return
if asn1Spec is None:
for asn1Object in self._decodeComponentsSchemaless(
substrate, tagSet=tagSet, decodeFun=decodeFun,
length=length, **dict(options, allowEoo=True)):
if isinstance(asn1Object, SubstrateUnderrunError):
yield asn1Object
yield asn1Object
return
asn1Object = asn1Spec.clone()
asn1Object.clear()
options = self._passAsn1Object(asn1Object, options)
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 True: # loop over components
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,)
)
for component in decodeFun(substrate, asn1Spec, allowEoo=True, **options):
if isinstance(component, SubstrateUnderrunError):
yield component
if component is eoo.endOfOctets:
break
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
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):
stream = asSeekableStream(containerValue[pos].asOctets())
for component in decodeFun(stream, asn1Spec=openType,
**dict(options, allowEoo=True)):
if isinstance(component, SubstrateUnderrunError):
yield component
if component is eoo.endOfOctets:
break
containerValue[pos] = component
else:
stream = asSeekableStream(asn1Object.getComponentByPosition(idx).asOctets())
for component in decodeFun(stream, asn1Spec=openType,
**dict(options, allowEoo=True)):
if isinstance(component, SubstrateUnderrunError):
yield component
if component is eoo.endOfOctets:
break
asn1Object.setComponentByPosition(idx, component)
else:
inconsistency = asn1Object.isInconsistent
if inconsistency:
raise error.PyAsn1Error(
f"ASN.1 object {asn1Object.__class__.__name__} is inconsistent")
else:
componentType = asn1Spec.componentType
if LOG:
LOG('decoding type %r chosen by given `asn1Spec`' % componentType)
idx = 0
while True:
for component in decodeFun(
substrate, componentType, allowEoo=True, **options):
if isinstance(component, SubstrateUnderrunError):
yield component
if component is eoo.endOfOctets:
break
if component is eoo.endOfOctets:
break
asn1Object.setComponentByPosition(
idx, component,
verifyConstraints=False,
matchTags=False, matchConstraints=False
)
idx += 1
yield asn1Object
class SequenceOrSequenceOfPayloadDecoder(ConstructedPayloadDecoderBase):
protoRecordComponent = univ.Sequence()
protoSequenceComponent = univ.SequenceOf()
class SequencePayloadDecoder(SequenceOrSequenceOfPayloadDecoder):
protoComponent = univ.Sequence()
class SequenceOfPayloadDecoder(SequenceOrSequenceOfPayloadDecoder):
protoComponent = univ.SequenceOf()
class SetOrSetOfPayloadDecoder(ConstructedPayloadDecoderBase):
protoRecordComponent = univ.Set()
protoSequenceComponent = univ.SetOf()
class SetPayloadDecoder(SetOrSetOfPayloadDecoder):
protoComponent = univ.Set()
class SetOfPayloadDecoder(SetOrSetOfPayloadDecoder):
protoComponent = univ.SetOf()
class ChoicePayloadDecoder(ConstructedPayloadDecoderBase):
protoComponent = univ.Choice()
def valueDecoder(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:
for chunk in substrateFun(asn1Object, substrate, length, options):
yield chunk
return
options = self._passAsn1Object(asn1Object, options)
if asn1Object.tagSet == tagSet:
if LOG:
LOG('decoding %s as explicitly tagged CHOICE' % (tagSet,))
for component in decodeFun(
substrate, asn1Object.componentTagMap, **options):
if isinstance(component, SubstrateUnderrunError):
yield component
else:
if LOG:
LOG('decoding %s as untagged CHOICE' % (tagSet,))
for component in decodeFun(
substrate, asn1Object.componentTagMap, tagSet, length,
state, **options):
if isinstance(component, SubstrateUnderrunError):
yield component
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
)
yield asn1Object
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:
for chunk in substrateFun(asn1Object, substrate, length, options):
yield chunk
return
options = self._passAsn1Object(asn1Object, options)
isTagged = asn1Object.tagSet == tagSet
if LOG:
LOG('decoding %s as %stagged CHOICE' % (
tagSet, isTagged and 'explicitly ' or 'un'))
while True:
if isTagged:
iterator = decodeFun(
substrate, asn1Object.componentType.tagMapUnique,
**dict(options, allowEoo=True))
else:
iterator = decodeFun(
substrate, asn1Object.componentType.tagMapUnique,
tagSet, length, state, **dict(options, allowEoo=True))
for component in iterator:
if isinstance(component, SubstrateUnderrunError):
yield component
if component is eoo.endOfOctets:
break
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
)
if not isTagged:
break
if not isTagged or component is eoo.endOfOctets:
break
yield asn1Object
class AnyPayloadDecoder(AbstractSimplePayloadDecoder):
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:
fullPosition = substrate.markedPosition
currentPosition = substrate.tell()
substrate.seek(fullPosition, os.SEEK_SET)
length += currentPosition - fullPosition
if LOG:
for chunk in peekIntoStream(substrate, length):
if isinstance(chunk, SubstrateUnderrunError):
yield chunk
LOG('decoding as untagged ANY, substrate '
'%s' % debug.hexdump(chunk))
if substrateFun:
for chunk in substrateFun(
self._createComponent(asn1Spec, tagSet, noValue, **options),
substrate, length, options):
yield chunk
return
for chunk in readFromStream(substrate, length, options):
if isinstance(chunk, SubstrateUnderrunError):
yield chunk
yield self._createComponent(asn1Spec, tagSet, chunk, **options)
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
chunk = b''
if LOG:
LOG('decoding as tagged ANY')
else:
# TODO: Seems not to be tested
fullPosition = substrate.markedPosition
currentPosition = substrate.tell()
substrate.seek(fullPosition, os.SEEK_SET)
for chunk in readFromStream(substrate, currentPosition - fullPosition, options):
if isinstance(chunk, SubstrateUnderrunError):
yield chunk
if LOG:
LOG('decoding as untagged ANY, header substrate %s' % debug.hexdump(chunk))
# 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)
for chunk in substrateFun(
asn1Object, chunk + substrate, length + len(chunk), options):
yield chunk
return
if LOG:
LOG('assembling constructed serialization')
# All inner fragments are of the same type, treat them as octet string
substrateFun = self.substrateCollector
while True: # loop over fragments
for component in decodeFun(
substrate, asn1Spec, substrateFun=substrateFun,
allowEoo=True, **options):
if isinstance(component, SubstrateUnderrunError):
yield component
if component is eoo.endOfOctets:
break
if component is eoo.endOfOctets:
break
chunk += component
if substrateFun:
yield chunk # TODO: Weird
else:
yield self._createComponent(asn1Spec, tagSet, chunk, **options)
# character string types
class UTF8StringPayloadDecoder(OctetStringPayloadDecoder):
protoComponent = char.UTF8String()
class NumericStringPayloadDecoder(OctetStringPayloadDecoder):
protoComponent = char.NumericString()
class PrintableStringPayloadDecoder(OctetStringPayloadDecoder):
protoComponent = char.PrintableString()
class TeletexStringPayloadDecoder(OctetStringPayloadDecoder):
protoComponent = char.TeletexString()
class VideotexStringPayloadDecoder(OctetStringPayloadDecoder):
protoComponent = char.VideotexString()
class IA5StringPayloadDecoder(OctetStringPayloadDecoder):
protoComponent = char.IA5String()
class GraphicStringPayloadDecoder(OctetStringPayloadDecoder):
protoComponent = char.GraphicString()
class VisibleStringPayloadDecoder(OctetStringPayloadDecoder):
protoComponent = char.VisibleString()
class GeneralStringPayloadDecoder(OctetStringPayloadDecoder):
protoComponent = char.GeneralString()
class UniversalStringPayloadDecoder(OctetStringPayloadDecoder):
protoComponent = char.UniversalString()
class BMPStringPayloadDecoder(OctetStringPayloadDecoder):
protoComponent = char.BMPString()
# "useful" types
class ObjectDescriptorPayloadDecoder(OctetStringPayloadDecoder):
protoComponent = useful.ObjectDescriptor()
class GeneralizedTimePayloadDecoder(OctetStringPayloadDecoder):
protoComponent = useful.GeneralizedTime()
class UTCTimePayloadDecoder(OctetStringPayloadDecoder):
protoComponent = useful.UTCTime()
TAG_MAP = {
univ.Integer.tagSet: IntegerPayloadDecoder(),
univ.Boolean.tagSet: BooleanPayloadDecoder(),
univ.BitString.tagSet: BitStringPayloadDecoder(),
univ.OctetString.tagSet: OctetStringPayloadDecoder(),
univ.Null.tagSet: NullPayloadDecoder(),
univ.ObjectIdentifier.tagSet: ObjectIdentifierPayloadDecoder(),
univ.RelativeOID.tagSet: RelativeOIDPayloadDecoder(),
univ.Enumerated.tagSet: IntegerPayloadDecoder(),
univ.Real.tagSet: RealPayloadDecoder(),
univ.Sequence.tagSet: SequenceOrSequenceOfPayloadDecoder(), # conflicts with SequenceOf
univ.Set.tagSet: SetOrSetOfPayloadDecoder(), # conflicts with SetOf
univ.Choice.tagSet: ChoicePayloadDecoder(), # conflicts with Any
# character string types
char.UTF8String.tagSet: UTF8StringPayloadDecoder(),
char.NumericString.tagSet: NumericStringPayloadDecoder(),
char.PrintableString.tagSet: PrintableStringPayloadDecoder(),
char.TeletexString.tagSet: TeletexStringPayloadDecoder(),
char.VideotexString.tagSet: VideotexStringPayloadDecoder(),
char.IA5String.tagSet: IA5StringPayloadDecoder(),
char.GraphicString.tagSet: GraphicStringPayloadDecoder(),
char.VisibleString.tagSet: VisibleStringPayloadDecoder(),
char.GeneralString.tagSet: GeneralStringPayloadDecoder(),
char.UniversalString.tagSet: UniversalStringPayloadDecoder(),
char.BMPString.tagSet: BMPStringPayloadDecoder(),
# useful types
useful.ObjectDescriptor.tagSet: ObjectDescriptorPayloadDecoder(),
useful.GeneralizedTime.tagSet: GeneralizedTimePayloadDecoder(),
useful.UTCTime.tagSet: UTCTimePayloadDecoder()
}
# Type-to-codec map for ambiguous ASN.1 types
TYPE_MAP = {
univ.Set.typeId: SetPayloadDecoder(),
univ.SetOf.typeId: SetOfPayloadDecoder(),
univ.Sequence.typeId: SequencePayloadDecoder(),
univ.SequenceOf.typeId: SequenceOfPayloadDecoder(),
univ.Choice.typeId: ChoicePayloadDecoder(),
univ.Any.typeId: AnyPayloadDecoder()
}
# Put in non-ambiguous types for faster codec lookup
for typeDecoder in TAG_MAP.values():
if typeDecoder.protoComponent is not None:
typeId = typeDecoder.protoComponent.__class__.typeId
if typeId is not None and typeId not in TYPE_MAP:
TYPE_MAP[typeId] = typeDecoder
(stDecodeTag,
stDecodeLength,
stGetValueDecoder,
stGetValueDecoderByAsn1Spec,
stGetValueDecoderByTag,
stTryAsExplicitTag,
stDecodeValue,
stDumpRawValue,
stErrorCondition,
stStop) = [x for x in range(10)]
EOO_SENTINEL = bytes((0, 0))
class SingleItemDecoder(object):
defaultErrorState = stErrorCondition
#defaultErrorState = stDumpRawValue
defaultRawDecoder = AnyPayloadDecoder()
supportIndefLength = True
TAG_MAP = TAG_MAP
TYPE_MAP = TYPE_MAP
def __init__(self, tagMap=_MISSING, typeMap=_MISSING, **ignored):
self._tagMap = tagMap if tagMap is not _MISSING else self.TAG_MAP
self._typeMap = typeMap if typeMap is not _MISSING else self.TYPE_MAP
# Tag & TagSet objects caches
self._tagCache = {}
self._tagSetCache = {}
def __call__(self, substrate, asn1Spec=None,
tagSet=None, length=None, state=stDecodeTag,
decodeFun=None, substrateFun=None,
**options):
allowEoo = options.pop('allowEoo', False)
if LOG:
LOG('decoder called at scope %s with state %d, working with up '
'to %s octets of substrate: '
'%s' % (debug.scope, state, length, substrate))
# Look for end-of-octets sentinel
if allowEoo and self.supportIndefLength:
for eoo_candidate in readFromStream(substrate, 2, options):
if isinstance(eoo_candidate, SubstrateUnderrunError):
yield eoo_candidate
if eoo_candidate == EOO_SENTINEL:
if LOG:
LOG('end-of-octets sentinel found')
yield eoo.endOfOctets
return
else:
substrate.seek(-2, os.SEEK_CUR)
tagMap = self._tagMap
typeMap = self._typeMap
tagCache = self._tagCache
tagSetCache = self._tagSetCache
value = noValue
substrate.markedPosition = substrate.tell()
while state is not stStop:
if state is stDecodeTag:
# Decode tag
isShortTag = True
for firstByte in readFromStream(substrate, 1, options):
if isinstance(firstByte, SubstrateUnderrunError):
yield firstByte
firstOctet = ord(firstByte)
try:
lastTag = tagCache[firstOctet]
except KeyError:
integerTag = firstOctet
tagClass = integerTag & 0xC0
tagFormat = integerTag & 0x20
tagId = integerTag & 0x1F
if tagId == 0x1F:
isShortTag = False
lengthOctetIdx = 0
tagId = 0
while True:
for integerByte in readFromStream(substrate, 1, options):
if isinstance(integerByte, SubstrateUnderrunError):
yield integerByte
if not integerByte:
raise error.SubstrateUnderrunError(
'Short octet stream on long tag decoding'
)
integerTag = ord(integerByte)
lengthOctetIdx += 1
tagId <<= 7
tagId |= (integerTag & 0x7F)
if not integerTag & 0x80:
break
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
for firstOctet in readFromStream(substrate, 1, options):
if isinstance(firstOctet, SubstrateUnderrunError):
yield firstOctet
firstOctet = ord(firstOctet)
if firstOctet < 128:
length = firstOctet
elif firstOctet > 128:
size = firstOctet & 0x7F
# encoded in size bytes
for encodedLength in readFromStream(substrate, size, options):
if isinstance(encodedLength, SubstrateUnderrunError):
yield encodedLength
encodedLength = list(encodedLength)
# 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: # 128 means indefinite
length = -1
if length == -1 and not self.supportIndefLength:
raise error.PyAsn1Error('Indefinite length encoding not supported by this codec')
state = stGetValueDecoder
if LOG:
LOG('value length decoded into %d' % 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
def substrateFun(asn1Object, _substrate, _length, _options):
"""Legacy hack to keep the recursiveFlag=False option supported.
The decode(..., substrateFun=userCallback) option was introduced in 0.1.4 as a generalization
of the old recursiveFlag=False option. Users should pass their callback instead of using
recursiveFlag.
"""
yield asn1Object
original_position = substrate.tell()
if length == -1: # indef length
for value in concreteDecoder.indefLenValueDecoder(
substrate, asn1Spec,
tagSet, length, stGetValueDecoder,
self, substrateFun, **options):
if isinstance(value, SubstrateUnderrunError):
yield value
else:
for value in concreteDecoder.valueDecoder(
substrate, asn1Spec,
tagSet, length, stGetValueDecoder,
self, substrateFun, **options):
if isinstance(value, SubstrateUnderrunError):
yield value
bytesRead = substrate.tell() - original_position
if not substrateFun and bytesRead != length:
raise PyAsn1Error(
"Read %s bytes instead of expected %s." % (bytesRead, length))
elif substrateFun and bytesRead > length:
# custom substrateFun may be used for partial decoding, reading less is expected there
raise PyAsn1Error(
"Read %s bytes are more than expected %s." % (bytesRead, length))
if LOG:
LOG('codec %s yields type %s, value:\n%s\n...' % (
concreteDecoder.__class__.__name__, value.__class__.__name__,
isinstance(value, base.Asn1Item) and value.prettyPrint() or value))
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 = rawPayloadDecoder
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)
yield value
class StreamingDecoder(object):
"""Create an iterator that turns BER/CER/DER byte stream into ASN.1 objects.
On each iteration, consume whatever BER/CER/DER serialization is
available in the `substrate` stream-like object and turns it into
one or more, possibly nested, ASN.1 objects.
Parameters
----------
substrate: :py:class:`file`, :py:class:`io.BytesIO`
BER/CER/DER serialization in form of a byte stream
Keyword Args
------------
asn1Spec: :py:class:`~pyasn1.type.base.PyAsn1Item`
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. One of the reasons why `asn1Spec` may
me required is that ASN.1 structure is encoded in the *IMPLICIT*
tagging mode.
Yields
------
: :py:class:`~pyasn1.type.base.PyAsn1Item`, :py:class:`~pyasn1.error.SubstrateUnderrunError`
Decoded ASN.1 object (possibly, nested) or
:py:class:`~pyasn1.error.SubstrateUnderrunError` object indicating
insufficient BER/CER/DER serialization on input to fully recover ASN.1
objects from it.
In the latter case the caller is advised to ensure some more data in
the input stream, then call the iterator again. The decoder will resume
the decoding process using the newly arrived data.
The `context` property of :py:class:`~pyasn1.error.SubstrateUnderrunError`
object might hold a reference to the partially populated ASN.1 object
being reconstructed.
Raises
------
~pyasn1.error.PyAsn1Error, ~pyasn1.error.EndOfStreamError
`PyAsn1Error` on deserialization error, `EndOfStreamError` on
premature stream closure.
Examples
--------
Decode BER serialisation without ASN.1 schema
.. code-block:: pycon
>>> stream = io.BytesIO(
... b'0\t\x02\x01\x01\x02\x01\x02\x02\x01\x03')
>>>
>>> for asn1Object in StreamingDecoder(stream):
... print(asn1Object)
>>>
SequenceOf:
1 2 3
Decode BER serialisation with ASN.1 schema
.. code-block:: pycon
>>> stream = io.BytesIO(
... b'0\t\x02\x01\x01\x02\x01\x02\x02\x01\x03')
>>>
>>> schema = SequenceOf(componentType=Integer())
>>>
>>> decoder = StreamingDecoder(stream, asn1Spec=schema)
>>> for asn1Object in decoder:
... print(asn1Object)
>>>
SequenceOf:
1 2 3
"""
SINGLE_ITEM_DECODER = SingleItemDecoder
def __init__(self, substrate, asn1Spec=None, **options):
self._singleItemDecoder = self.SINGLE_ITEM_DECODER(**options)
self._substrate = asSeekableStream(substrate)
self._asn1Spec = asn1Spec
self._options = options
def __iter__(self):
while True:
for asn1Object in self._singleItemDecoder(
self._substrate, self._asn1Spec, **self._options):
yield asn1Object
for chunk in isEndOfStream(self._substrate):
if isinstance(chunk, SubstrateUnderrunError):
yield
break
if chunk:
break
class Decoder(object):
"""Create a BER decoder object.
Parse BER/CER/DER octet-stream into one, possibly nested, ASN.1 object.
"""
STREAMING_DECODER = StreamingDecoder
@classmethod
def __call__(cls, substrate, asn1Spec=None, **options):
"""Turns BER/CER/DER octet stream into an ASN.1 object.
Takes BER/CER/DER octet-stream in form of :py:class:`bytes`
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`
BER/CER/DER octet-stream to parse
Keyword Args
------------
asn1Spec: :py:class:`~pyasn1.type.base.PyAsn1Item`
A pyasn1 type object (:py:class:`~pyasn1.type.base.PyAsn1Item`
derivative) 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.
substrateFun: :py:class:`Union[
Callable[[pyasn1.type.base.PyAsn1Item, bytes, int],
Tuple[pyasn1.type.base.PyAsn1Item, bytes]],
Callable[[pyasn1.type.base.PyAsn1Item, io.BytesIO, int, dict],
Generator[Union[pyasn1.type.base.PyAsn1Item,
pyasn1.error.SubstrateUnderrunError],
None, None]]
]`
User callback meant to generalize special use cases like non-recursive or
partial decoding. A 3-arg non-streaming variant is supported for backwards
compatiblilty in addition to the newer 4-arg streaming variant.
The callback will receive the uninitialized object recovered from substrate
as 1st argument, the uninterpreted payload as 2nd argument, and the length
of the uninterpreted payload as 3rd argument. The streaming variant will
additionally receive the decode(..., **options) kwargs as 4th argument.
The non-streaming variant shall return an object that will be propagated
as decode() return value as 1st item, and the remainig payload for further
decode passes as 2nd item.
The streaming variant shall yield an object that will be propagated as
decode() return value, and leave the remaining payload in the stream.
Returns
-------
: :py:class:`tuple`
A tuple of :py:class:`~pyasn1.type.base.PyAsn1Item` object
recovered from BER/CER/DER substrate and the unprocessed trailing
portion of the `substrate` (may be empty)
Raises
------
: :py:class:`~pyasn1.error.PyAsn1Error`
:py:class:`~pyasn1.error.SubstrateUnderrunError` on insufficient
input or :py:class:`~pyasn1.error.PyAsn1Error` on decoding error.
Examples
--------
Decode BER/CER/DER serialisation without ASN.1 schema
.. code-block:: pycon
>>> s, unprocessed = decode(b'0\t\x02\x01\x01\x02\x01\x02\x02\x01\x03')
>>> str(s)
SequenceOf:
1 2 3
Decode BER/CER/DER serialisation with ASN.1 schema
.. code-block:: pycon
>>> seq = SequenceOf(componentType=Integer())
>>> s, unprocessed = decode(
b'0\t\x02\x01\x01\x02\x01\x02\x02\x01\x03', asn1Spec=seq)
>>> str(s)
SequenceOf:
1 2 3
"""
substrate = asSeekableStream(substrate)
if "substrateFun" in options:
origSubstrateFun = options["substrateFun"]
def substrateFunWrapper(asn1Object, substrate, length, options=None):
"""Support both 0.4 and 0.5 style APIs.
substrateFun API has changed in 0.5 for use with streaming decoders. To stay backwards compatible,
we first try if we received a streaming user callback. If that fails,we assume we've received a
non-streaming v0.4 user callback and convert it for streaming on the fly
"""
try:
substrate_gen = origSubstrateFun(asn1Object, substrate, length, options)
except TypeError as _value:
if _value.__traceback__.tb_next:
# Traceback depth > 1 means TypeError from inside user provided function
raise
# invariant maintained at Decoder.__call__ entry
assert isinstance(substrate, io.BytesIO) # nosec assert_used
substrate_gen = Decoder._callSubstrateFunV4asV5(origSubstrateFun, asn1Object, substrate, length)
for value in substrate_gen:
yield value
options["substrateFun"] = substrateFunWrapper
streamingDecoder = cls.STREAMING_DECODER(
substrate, asn1Spec, **options)
for asn1Object in streamingDecoder:
if isinstance(asn1Object, SubstrateUnderrunError):
raise error.SubstrateUnderrunError('Short substrate on input')
try:
tail = next(readFromStream(substrate))
except error.EndOfStreamError:
tail = b''
return asn1Object, tail
@staticmethod
def _callSubstrateFunV4asV5(substrateFunV4, asn1Object, substrate, length):
substrate_bytes = substrate.read()
if length == -1:
length = len(substrate_bytes)
value, nextSubstrate = substrateFunV4(asn1Object, substrate_bytes, length)
nbytes = substrate.write(nextSubstrate)
substrate.truncate()
substrate.seek(-nbytes, os.SEEK_CUR)
yield value
#: 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`
#: 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
#:
#: Notes
#: -----
#: This function is deprecated. Please use :py:class:`Decoder` or
#: :py:class:`StreamingDecoder` class instance.
#:
#: 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()
def __getattr__(attr: str):
if newAttr := {"tagMap": "TAG_MAP", "typeMap": "TYPE_MAP"}.get(attr):
warnings.warn(f"{attr} is deprecated. Please use {newAttr} instead.", DeprecationWarning)
return globals()[newAttr]
raise AttributeError(attr)