def valueDecoder(self, fullSubstrate, substrate, asn1Spec, tagSet, length,
state, decodeFun, substrateFun):
head, tail = substrate[:length], substrate[length:]
if not head:
raise error.PyAsn1Error('Empty substrate')
# Get the first subid
subId = oct2int(head[0])
oid = divmod(subId, 40)
index = 1
substrateLen = len(head)
while index < substrateLen:
subId = oct2int(head[index])
index = index + 1
if subId == 128:
# ASN.1 spec forbids leading zeros (0x80) in sub-ID OID
# encoding, tolerating it opens a vulnerability.
# See http://www.cosic.esat.kuleuven.be/publications/article-1432.pdf page 7
raise error.PyAsn1Error('Invalid leading 0x80 in sub-OID')
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 = oct2int(head[index])
index = index + 1
subId = (subId << 7) + nextSubId
oid = oid + (subId, )
return self._createComponent(asn1Spec, tagSet, oid), tail
def valueDecoder(self, fullSubstrate, substrate, asn1Spec, tagSet, length,
state, decodeFun, substrateFun):
head, tail = substrate[:length], substrate[length:]
if tagSet[0][1] == tag.tagFormatSimple: # XXX what tag to check?
if not head:
raise error.PyAsn1Error('Empty substrate')
trailingBits = oct2int(head[0])
if trailingBits > 7:
raise error.PyAsn1Error('Trailing bits overflow %s' %
trailingBits)
head = head[1:]
lsb = p = 0
l = len(head) - 1
b = ()
while p <= l:
if p == l:
lsb = trailingBits
j = 7
o = oct2int(head[p])
while j >= lsb:
b = b + ((o >> j) & 0x01, )
j = j - 1
p = p + 1
return self._createComponent(asn1Spec, tagSet, b), tail
r = self._createComponent(asn1Spec, tagSet, ())
if substrateFun:
return substrateFun(r, substrate, length)
while head:
component, head = decodeFun(head)
r = r + component
return r, tail
def valueDecoder(self, fullSubstrate, substrate, asn1Spec, tagSet, length,
state, decodeFun, substrateFun):
head, tail = substrate[:length], substrate[length:]
if not head:
return self._createComponent(asn1Spec, tagSet, 0), tail
if head in self.precomputedValues:
value = self.precomputedValues[head]
else:
firstOctet = oct2int(head[0])
if firstOctet & 0x80:
value = -1
else:
value = 0
for octet in head:
value = value << 8 | oct2int(octet)
return self._createComponent(asn1Spec, tagSet, value), tail
def valueDecoder(self, fullSubstrate, substrate, asn1Spec, tagSet, length,
state, decodeFun, substrateFun):
head, tail = substrate[:length], substrate[length:]
if not head:
return self._createComponent(asn1Spec, tagSet, 0.0), tail
fo = oct2int(head[0])
head = head[1:]
if fo & 0x80: # binary enoding
n = (fo & 0x03) + 1
if n == 4:
n = oct2int(head[0])
eo, head = head[:n], head[n:]
if not eo or not head:
raise error.PyAsn1Error('Real exponent screwed')
e = oct2int(eo[0]) & 0x80 and -1 or 0
while eo: # exponent
e <<= 8
e |= oct2int(eo[0])
eo = eo[1:]
p = 0
while head: # value
p <<= 8
p |= oct2int(head[0])
head = head[1:]
if fo & 0x40: # sign bit
p = -p
value = (p, 2, e)
elif fo & 0x40: # infinite value
value = fo & 0x01 and '-inf' or 'inf'
elif fo & 0xc0 == 0: # character encoding
try:
if fo & 0x3 == 0x1: # NR1
value = (int(head), 10, 0)
elif fo & 0x3 == 0x2: # NR2
value = float(head)
elif fo & 0x3 == 0x3: # NR3
value = float(head)
else:
raise error.SubstrateUnderrunError('Unknown NR (tag %s)' %
fo)
except ValueError:
raise error.SubstrateUnderrunError('Bad character Real syntax')
else:
raise error.SubstrateUnderrunError('Unknown encoding (tag %s)' %
fo)
return self._createComponent(asn1Spec, tagSet, value), tail
def valueDecoder(self, fullSubstrate, substrate, asn1Spec, tagSet, length,
state, decodeFun, substrateFun):
head, tail = substrate[:length], substrate[length:]
if not head:
raise error.PyAsn1Error('Empty substrate')
byte = oct2int(head[0])
# CER/DER specifies encoding of TRUE as 0xFF and FALSE as 0x0, while
# BER allows any non-zero value as TRUE; cf. sections 8.2.2. and 11.1
# in http://www.itu.int/ITU-T/studygroups/com17/languages/X.690-0207.pdf
if byte == 0xff:
value = 1
elif byte == 0x00:
value = 0
else:
raise error.PyAsn1Error('Boolean CER violation: %s' % byte)
return self._createComponent(asn1Spec, tagSet, value), tail
def encodeValue(self, encodeFun, value, defMode, maxChunkSize):
if value.isPlusInfinity():
return int2oct(0x40), 0
if value.isMinusInfinity():
return int2oct(0x41), 0
m, b, e = value
if not m:
return null, 0
if b == 10:
return str2octs('\x03%dE%s%d' % (m, e == 0 and '+' or '', e)), 0
elif b == 2:
fo = 0x80 # binary enoding
if m < 0:
fo = fo | 0x40 # sign bit
m = -m
while int(m) != m: # drop floating point
m *= 2
e -= 1
while m & 0x1 == 0: # mantissa normalization
m >>= 1
e += 1
eo = null
while e not in (0, -1):
eo = int2oct(e & 0xff) + eo
e >>= 8
if e == 0 and eo and oct2int(eo[0]) & 0x80:
eo = int2oct(0) + eo
n = len(eo)
if n > 0xff:
raise error.PyAsn1Error('Real exponent overflow')
if n == 1:
pass
elif n == 2:
fo |= 1
elif n == 3:
fo |= 2
else:
fo |= 3
eo = int2oct(n // 0xff + 1) + eo
po = null
while m:
po = int2oct(m & 0xff) + po
m >>= 8
substrate = int2oct(fo) + eo + po
return substrate, 0
else:
raise error.PyAsn1Error('Prohibited Real base %s' % b)
def __call__(self,
substrate,
asn1Spec=None,
tagSet=None,
length=None,
state=stDecodeTag,
recursiveFlag=1,
substrateFun=None):
if debug.logger & debug.flagDecoder:
debug.logger(
'decoder called at scope %s with state %d, working with up to %d octets of substrate: %s'
%
(debug.scope, state, len(substrate), debug.hexdump(substrate)))
fullSubstrate = substrate
while state != stStop:
if state == stDecodeTag:
# Decode tag
if not substrate:
raise error.SubstrateUnderrunError(
'Short octet stream on tag decoding')
if not isOctetsType(substrate) and \
not isinstance(substrate, univ.OctetString):
raise error.PyAsn1Error('Bad octet stream type')
firstOctet = substrate[0]
substrate = substrate[1:]
if firstOctet in self.__tagCache:
lastTag = self.__tagCache[firstOctet]
else:
t = oct2int(firstOctet)
tagClass = t & 0xC0
tagFormat = t & 0x20
tagId = t & 0x1F
if tagId == 0x1F:
tagId = 0
while 1:
if not substrate:
raise error.SubstrateUnderrunError(
'Short octet stream on long tag decoding')
t = oct2int(substrate[0])
tagId = tagId << 7 | (t & 0x7F)
substrate = substrate[1:]
if not t & 0x80:
break
lastTag = tag.Tag(tagClass=tagClass,
tagFormat=tagFormat,
tagId=tagId)
if tagId < 31:
# cache short tags
self.__tagCache[firstOctet] = lastTag
if tagSet is None:
if firstOctet in self.__tagSetCache:
tagSet = self.__tagSetCache[firstOctet]
else:
# base tag not recovered
tagSet = tag.TagSet((), lastTag)
if firstOctet in self.__tagCache:
self.__tagSetCache[firstOctet] = tagSet
else:
tagSet = lastTag + tagSet
state = stDecodeLength
debug.logger and debug.logger & debug.flagDecoder and debug.logger(
'tag decoded into %r, decoding length' % tagSet)
if state == 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 = -1
elif firstOctet < 128:
length, size = firstOctet, 1
else:
size = firstOctet & 0x7F
# encoded in size bytes
length = 0
lengthString = substrate[1:size + 1]
# missing check on maximum size, which shouldn't be a
# problem, we can handle more than is possible
if len(lengthString) != size:
raise error.SubstrateUnderrunError(
'%s<%s at %s' % (size, len(lengthString), tagSet))
for char in lengthString:
length = (length << 8) | oct2int(char)
size = size + 1
substrate = substrate[size:]
if length != -1 and len(substrate) < length:
raise error.SubstrateUnderrunError(
'%d-octet short' % (length - len(substrate)))
state = stGetValueDecoder
debug.logger and debug.logger & debug.flagDecoder and debug.logger(
'value length decoded into %d, payload substrate is: %s' %
(length,
debug.hexdump(length == -1 and substrate
or substrate[:length])))
if state == 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 == stGetValueDecoderByTag:
if tagSet in self.__tagMap:
concreteDecoder = self.__tagMap[tagSet]
else:
concreteDecoder = None
if concreteDecoder:
state = stDecodeValue
else:
_k = tagSet[:1]
if _k in self.__tagMap:
concreteDecoder = self.__tagMap[_k]
else:
concreteDecoder = None
if concreteDecoder:
state = stDecodeValue
else:
state = stTryAsExplicitTag
if debug.logger and debug.logger & debug.flagDecoder:
debug.logger(
'codec %s chosen by a built-in type, decoding %s' %
(concreteDecoder and concreteDecoder.__class__.__name__
or "<none>", state == stDecodeValue and 'value'
or 'as explicit tag'))
debug.scope.push(
concreteDecoder is None and '?'
or concreteDecoder.protoComponent.__class__.__name__)
if state == stGetValueDecoderByAsn1Spec:
if isinstance(asn1Spec, (dict, tagmap.TagMap)):
if tagSet in asn1Spec:
__chosenSpec = asn1Spec[tagSet]
else:
__chosenSpec = None
if debug.logger and debug.logger & debug.flagDecoder:
debug.logger('candidate ASN.1 spec is a map of:')
for t, v in asn1Spec.getPosMap().items():
debug.logger(' %r -> %s' %
(t, v.__class__.__name__))
if asn1Spec.getNegMap():
debug.logger('but neither of: ')
for i in asn1Spec.getNegMap().items():
debug.logger(' %r -> %s' %
(t, v.__class__.__name__))
debug.logger(
'new candidate ASN.1 spec is %s, chosen by %r' %
(__chosenSpec is None and '<none>'
or __chosenSpec.__class__.__name__, tagSet))
else:
__chosenSpec = asn1Spec
debug.logger and debug.logger & debug.flagDecoder and debug.logger(
'candidate ASN.1 spec is %s' %
asn1Spec.__class__.__name__)
if __chosenSpec is not None and (
tagSet == __chosenSpec.getTagSet() or \
tagSet in __chosenSpec.getTagMap()
):
# use base type for codec lookup to recover untagged types
baseTagSet = __chosenSpec.baseTagSet
if __chosenSpec.typeId is not None and \
__chosenSpec.typeId in self.__typeMap:
# ambiguous type
concreteDecoder = self.__typeMap[__chosenSpec.typeId]
debug.logger and debug.logger & debug.flagDecoder and debug.logger(
'value decoder chosen for an ambiguous type by type ID %s'
% (__chosenSpec.typeId, ))
elif baseTagSet in self.__tagMap:
# base type or tagged subtype
concreteDecoder = self.__tagMap[baseTagSet]
debug.logger and debug.logger & debug.flagDecoder and debug.logger(
'value decoder chosen by base %r' % (baseTagSet, ))
else:
concreteDecoder = None
if concreteDecoder:
asn1Spec = __chosenSpec
state = stDecodeValue
else:
state = stTryAsExplicitTag
elif tagSet == self.__endOfOctetsTagSet:
concreteDecoder = self.__tagMap[tagSet]
state = stDecodeValue
debug.logger and debug.logger & debug.flagDecoder and debug.logger(
'end-of-octets found')
else:
concreteDecoder = None
state = stTryAsExplicitTag
if debug.logger and debug.logger & debug.flagDecoder:
debug.logger(
'codec %s chosen by ASN.1 spec, decoding %s' %
(state == stDecodeValue
and concreteDecoder.__class__.__name__
or "<none>", state == stDecodeValue and 'value'
or 'as explicit tag'))
debug.scope.push(__chosenSpec is None and '?'
or __chosenSpec.__class__.__name__)
if state == stTryAsExplicitTag:
if tagSet and \
tagSet[0][1] == tag.tagFormatConstructed and \
tagSet[0][0] != tag.tagClassUniversal:
# Assume explicit tagging
concreteDecoder = explicitTagDecoder
state = stDecodeValue
else:
concreteDecoder = None
state = self.defaultErrorState
debug.logger and debug.logger & debug.flagDecoder and debug.logger(
'codec %s chosen, decoding %s' %
(concreteDecoder and concreteDecoder.__class__.__name__
or "<none>", state == stDecodeValue and 'value'
or 'as failure'))
if state == stDumpRawValue:
concreteDecoder = self.defaultRawDecoder
debug.logger and debug.logger & debug.flagDecoder and debug.logger(
'codec %s chosen, decoding value' %
concreteDecoder.__class__.__name__)
state = stDecodeValue
if state == stDecodeValue:
if recursiveFlag == 0 and not substrateFun: # legacy
substrateFun = lambda a, b, c: (a, b[:c])
if length == -1: # indef length
value, substrate = concreteDecoder.indefLenValueDecoder(
fullSubstrate, substrate, asn1Spec, tagSet, length,
stGetValueDecoder, self, substrateFun)
else:
value, substrate = concreteDecoder.valueDecoder(
fullSubstrate, substrate, asn1Spec, tagSet, length,
stGetValueDecoder, self, substrateFun)
state = stStop
debug.logger and debug.logger & debug.flagDecoder and debug.logger(
'codec %s yields type %s, value:\n%s\n...remaining substrate is: %s'
% (concreteDecoder.__class__.__name__,
value.__class__.__name__, value.prettyPrint(),
substrate and debug.hexdump(substrate) or '<none>'))
if state == stErrorCondition:
raise error.PyAsn1Error('%r not in asn1Spec: %r' %
(tagSet, asn1Spec))
if debug.logger and debug.logger & debug.flagDecoder:
debug.scope.pop()
debug.logger('decoder left scope %s, call completed' % debug.scope)
return value, substrate