def encodeValue(self, value, asn1Spec, encodeFun, **options):
if asn1Spec is None:
substrate = value.asOctets()
elif not isOctetsType(value):
substrate = asn1Spec.clone(value).asOctets()
else:
substrate = value
maxChunkSize = options.get('maxChunkSize', 0)
if not maxChunkSize or len(substrate) <= maxChunkSize:
return substrate, False, True
if LOG:
LOG('encoding into up to %s-octet chunks' % maxChunkSize)
# strip off explicit tags for inner chunks
if asn1Spec is None:
baseTag = value.tagSet.baseTag
# strip off explicit tags
if baseTag:
tagSet = tag.TagSet(baseTag, baseTag)
else:
tagSet = tag.TagSet()
asn1Spec = value.clone(tagSet=tagSet)
elif not isOctetsType(value):
baseTag = asn1Spec.tagSet.baseTag
# strip off explicit tags
if baseTag:
tagSet = tag.TagSet(baseTag, baseTag)
else:
tagSet = tag.TagSet()
asn1Spec = asn1Spec.clone(tagSet=tagSet)
pos = 0
substrate = null
while True:
chunk = value[pos:pos + maxChunkSize]
if not chunk:
break
substrate += encodeFun(chunk, asn1Spec, **options)
pos += maxChunkSize
return substrate, True, True
def encodeValue(self, value, asn1Spec, encodeFun, **options):
if asn1Spec is None:
substrate = value.asOctets()
elif not isOctetsType(value):
substrate = asn1Spec.clone(value).asOctets()
else:
substrate = value
maxChunkSize = options.get('maxChunkSize', 0)
if not maxChunkSize or len(substrate) <= maxChunkSize:
return substrate, False, True
if LOG:
LOG('encoding into up to %s-octet chunks' % maxChunkSize)
# strip off explicit tags for inner chunks
if asn1Spec is None:
baseTag = value.tagSet.baseTag
# strip off explicit tags
if baseTag:
tagSet = tag.TagSet(baseTag, baseTag)
else:
tagSet = tag.TagSet()
asn1Spec = value.clone(tagSet=tagSet)
elif not isOctetsType(value):
baseTag = asn1Spec.tagSet.baseTag
# strip off explicit tags
if baseTag:
tagSet = tag.TagSet(baseTag, baseTag)
else:
tagSet = tag.TagSet()
asn1Spec = asn1Spec.clone(tagSet=tagSet)
pos = 0
substrate = null
while True:
chunk = value[pos:pos + maxChunkSize]
if not chunk:
break
substrate += encodeFun(chunk, asn1Spec, **options)
pos += maxChunkSize
return substrate, True, True
def encodeValue(self, value, asn1Spec, encodeFun, **options):
if asn1Spec is None:
value = value.asOctets()
elif not isOctetsType(value):
value = asn1Spec.clone(value).asOctets()
return value, not options.get('defMode', True), True
def encodeValue(self, value, asn1Spec, encodeFun, **options):
if asn1Spec is None:
# will strip off explicit tags
tagSet = value.tagSet
asn1Spec = value.clone(
tagSet=tag.TagSet(tagSet.baseTag, tagSet.baseTag))
value = value.asOctets()
elif not isOctetsType(value):
# will strip off explicit tags
tagSet = asn1Spec.tagSet
asn1Spec = asn1Spec.clone(
tagSet=tag.TagSet(tagSet.baseTag, tagSet.baseTag))
value = asn1Spec.clone(value).asOctets()
maxChunkSize = options.get('maxChunkSize', 0)
if not maxChunkSize or len(value) <= maxChunkSize:
return value, False, True
else:
pos = 0
substrate = null
while True:
chunk = value[pos:pos + maxChunkSize]
if not chunk:
break
substrate += encodeFun(chunk, asn1Spec, **options)
pos += maxChunkSize
return substrate, True, True
def encodeValue(self, value, asn1Spec, encodeFun, **options):
if asn1Spec is None:
value = value.asOctets()
elif not isOctetsType(value):
value = asn1Spec.clone(value).asOctets()
return value, not options.get('defMode', True), True
def evaluateValue(self, oid, tag, value, **context):
tag, encodingId = self.unpackTag(tag)
try:
if encodingId == 'e':
value = self.evaluateRawString(value)
return oid, tag, self.grammar.TAG_MAP[tag](value)
elif encodingId == 'x':
if octets.isOctetsType(value):
value = octets.octs2str(value)
return oid, tag, self.grammar.TAG_MAP[tag](hexValue=value)
else:
return oid, tag, self.grammar.TAG_MAP[tag](value)
except Exception:
raise error.SnmpsimError(
'value evaluation error for tag %r, value '
'%r: %s' % (tag, value, sys.exc_info()[1]))
def evaluate_value(self, oid, tag, value, **context):
tag, encoding_id = self.unpack_tag(tag)
try:
if encoding_id == 'e':
value = self.evaluate_raw_string(value)
return oid, tag, self.grammar.TAG_MAP[tag](value)
elif encoding_id == 'x':
if octets.isOctetsType(value):
value = octets.octs2str(value)
return oid, tag, self.grammar.TAG_MAP[tag](hexValue=value)
else:
return oid, tag, self.grammar.TAG_MAP[tag](value)
except Exception as exc:
raise error.SnmpsimError(
'value evaluation error for tag %r, value '
'%r: %s' % (tag, value, exc))
def evaluateValue(self, oid, tag, value, **context):
tag, encodingId = self.unpackTag(tag)
try:
if encodingId == 'e':
value = self.evaluateRawString(value)
return oid, tag, self.grammar.TAG_MAP[tag](value)
elif encodingId == 'x':
if octets.isOctetsType(value):
value = octets.octs2str(value)
return oid, tag, self.grammar.TAG_MAP[tag](hexValue=value)
else:
return oid, tag, self.grammar.TAG_MAP[tag](value)
except Exception:
raise error.SnmpsimError(
'value evaluation error for tag %r, value '
'%r: %s' % (tag, value, sys.exc_info()[1]))
def prettyIn(self, value): # override asn1 type method
"""Implements DISPLAY-HINT parsing into base SNMP value
Proper parsing seems impossible due to ambiguities.
Here we are trying to do our best, but be prepared
for failures on complicated DISPLAY-HINTs.
Keep in mind that this parser only works with "text"
input meaning `unicode` (Py2) or `str` (Py3).
"""
for base in inspect.getmro(self.__class__):
if not issubclass(base, TextualConvention) and issubclass(
base, Asn1Item):
break
else:
raise SmiError(
'TEXTUAL-CONVENTION has no underlying SNMP base type')
if self.displayHint and (
self.__integer.isSuperTypeOf(self, matchConstraints=False)
and self.getNamedValues() or self.__unsigned32.isSuperTypeOf(
self, matchConstraints=False) or
self.__timeticks.isSuperTypeOf(self, matchConstraints=False)):
value = str(value)
_ = lambda t, f=0: (t, f)
displayHintType, decimalPrecision = _(*self.displayHint.split('-'))
if displayHintType == 'x' and (value.startswith('0x')
or value.startswith('-0x')):
try:
if value.startswith('-'):
return base.prettyIn(self, -int(value[3:], 16))
else:
return base.prettyIn(self, int(value[2:], 16))
except Exception:
raise SmiError('integer evaluation error: %s' %
sys.exc_info()[1])
elif displayHintType == 'd':
try:
return base.prettyIn(
self, int(float(value) * 10**int(decimalPrecision)))
except Exception:
raise SmiError('float evaluation error: %s' %
sys.exc_info()[1])
elif displayHintType == 'o' and (value.startswith('0')
or value.startswith('-0')):
try:
return base.prettyIn(self, int(value, 8))
except Exception:
raise SmiError('octal evaluation error: %s' %
sys.exc_info()[1])
elif displayHintType == 'b' and (value.startswith('B')
or value.startswith('-B')):
negative = value.startswith('-')
if negative:
value = value[2:]
else:
value = value[1:]
value = [x != '0' and 1 or 0 for x in value]
binValue = 0
while value:
binValue <<= value[0]
del value[0]
return base.prettyIn(self, binValue)
else:
raise SmiError('Unsupported numeric type spec "%s" at %s' %
(displayHintType, self.__class__.__name__))
elif self.displayHint and self.__octetString.isSuperTypeOf(
self, matchConstraints=False):
numBase = {'x': 16, 'd': 10, 'o': 8}
numDigits = {
'x': octets.str2octs(string.hexdigits),
'o': octets.str2octs(string.octdigits),
'd': octets.str2octs(string.digits)
}
# how do we know if object is initialized with display-hint
# formatted text? based on "text" input maybe?
# That boils down to `str` object on Py3 or `unicode` on Py2.
if octets.isStringType(value) and not octets.isOctetsType(value):
value = base.prettyIn(self, value)
else:
return base.prettyIn(self, value)
outputValue = octets.str2octs('')
runningValue = value
displayHint = self.displayHint
while runningValue and displayHint:
# 1 this information is totally lost, just fail explicitly
if displayHint[0] == '*':
raise SmiError('Can\'t parse "*" in DISPLAY-HINT (%s)' %
self.__class__.__name__)
# 2 this becomes ambiguous when it comes to rendered value
octetLength = ''
while displayHint and displayHint[0] in string.digits:
octetLength += displayHint[0]
displayHint = displayHint[1:]
# length is mandatory but people ignore that
if not octetLength:
octetLength = len(runningValue)
try:
octetLength = int(octetLength)
except Exception:
raise SmiError('Bad octet length: %s' % octetLength)
if not displayHint:
raise SmiError('Short octet length: %s' % self.displayHint)
# 3
displayFormat = displayHint[0]
displayHint = displayHint[1:]
# 4 this is the lifesaver -- we could use it as an anchor
if displayHint and displayHint[
0] not in string.digits and displayHint[0] != '*':
displaySep = displayHint[0]
displayHint = displayHint[1:]
else:
displaySep = ''
# 5 is probably impossible to support
if displayFormat in ('a', 't'):
outputValue += runningValue[:octetLength]
elif displayFormat in numBase:
if displaySep:
guessedOctetLength = runningValue.find(
octets.str2octs(displaySep))
if guessedOctetLength == -1:
guessedOctetLength = len(runningValue)
else:
for idx in range(len(runningValue)):
if runningValue[idx] not in numDigits[
displayFormat]:
guessedOctetLength = idx
break
else:
guessedOctetLength = len(runningValue)
try:
num = int(
octets.octs2str(runningValue[:guessedOctetLength]),
numBase[displayFormat])
except Exception:
raise SmiError('Display format eval failure: %s: %s' %
(runningValue[:guessedOctetLength],
sys.exc_info()[1]))
num_as_bytes = []
if num:
while num:
num_as_bytes.append(num & 0xFF)
num >>= 8
else:
num_as_bytes = [0]
while len(num_as_bytes) < octetLength:
num_as_bytes.append(0)
num_as_bytes.reverse()
outputValue += octets.ints2octs(num_as_bytes)
if displaySep:
guessedOctetLength += 1
octetLength = guessedOctetLength
else:
raise SmiError('Unsupported display format char: %s' %
displayFormat)
runningValue = runningValue[octetLength:]
if not displayHint:
displayHint = self.displayHint
return base.prettyIn(self, outputValue)
else:
return base.prettyIn(self, value)
def __call__(self, substrate, asn1Spec=None, tagSet=None,
length=None, state=stDecodeTag, recursiveFlag=1,
substrateFun=None, allowEoo=False):
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)))
if asn1Spec is not None and not isinstance(asn1Spec, (base.Asn1Item, tagmap.TagMap)):
raise error.PyAsn1Error('asn1Spec is not valid (should be an instance of an ASN.1 Item, not %s)' % asn1Spec.__class__.__name__)
fullSubstrate = substrate
while state != stStop:
if state == stDecodeTag:
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')
# Decode tag
firstOctet = substrate[0]
substrate = substrate[1:]
if firstOctet in self.__tagCache:
lastTag = self.__tagCache[firstOctet]
else:
t = oct2int(firstOctet)
# Look for end-of-octets sentinel
if t == 0:
if substrate and oct2int(substrate[0]) == 0:
if allowEoo and self.supportIndefLength:
debug.logger and debug.logger & debug.flagDecoder and debug.logger('end-of-octets sentinel found')
value, substrate = eoo.endOfOctets, substrate[1:]
state = stStop
continue
else:
raise error.PyAsn1Error('Unexpected end-of-contents sentinel')
else:
raise error.PyAsn1Error('Zero tag encountered')
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 %s, 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 += 1
substrate = substrate[size:]
if length != -1 and len(substrate) < length:
raise error.SubstrateUnderrunError(
'%d-octet short' % (length - len(substrate))
)
if length == -1 and not self.supportIndefLength:
error.PyAsn1Error('Indefinite length encoding not supported by this codec')
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(' %s -> %s' % (t, v.__class__.__name__))
if asn1Spec.getNegMap():
debug.logger('but neither of: ')
for t, v in asn1Spec.getNegMap().items():
debug.logger(' %s -> %s' % (t, v.__class__.__name__))
debug.logger('new candidate ASN.1 spec is %s, chosen by %s' % (__chosenSpec is None and '<none>' or __chosenSpec.prettyPrintType(), 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 %s' % (baseTagSet,))
else:
concreteDecoder = None
if concreteDecoder:
asn1Spec = __chosenSpec
state = stDecodeValue
else:
state = stTryAsExplicitTag
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(
'%s not in asn1Spec: %s' % (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
def test_isOctetsType(self):
assert octets.isOctetsType('abc') == True
assert octets.isOctetsType(123) == False
assert octets.isOctetsType(unicode('abc')) == False
def test_isOctetsType(self):
assert octets.isOctetsType('abc') == False
assert octets.isOctetsType(123) == False
assert octets.isOctetsType(bytes()) == True
def __call__(self,
substrate,
asn1Spec=None,
tagSet=None,
length=None,
state=stDecodeTag,
recursiveFlag=1,
substrateFun=None,
allowEoo=False):
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)))
if asn1Spec is not None and not isinstance(
asn1Spec, (base.Asn1Item, tagmap.TagMap)):
raise error.PyAsn1Error(
'asn1Spec is not valid (should be an instance of an ASN.1 Item, not %s)'
% asn1Spec.__class__.__name__)
value = base.noValue
fullSubstrate = substrate
while state != stStop:
if state == stDecodeTag:
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')
# Decode tag
firstOctet = substrate[0]
substrate = substrate[1:]
if firstOctet in self.__tagCache:
lastTag = self.__tagCache[firstOctet]
else:
t = oct2int(firstOctet)
# Look for end-of-octets sentinel
if t == 0:
if substrate and oct2int(substrate[0]) == 0:
if allowEoo and self.supportIndefLength:
debug.logger and debug.logger & debug.flagDecoder and debug.logger(
'end-of-octets sentinel found')
value, substrate = eoo.endOfOctets, substrate[
1:]
state = stStop
continue
else:
raise error.PyAsn1Error(
'Unexpected end-of-contents sentinel')
else:
raise error.PyAsn1Error('Zero tag encountered')
tagClass = t & 0xC0
tagFormat = t & 0x20
tagId = t & 0x1F
short = True
if tagId == 0x1F:
short = False
tagId = 0
while True:
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 short:
# 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 %s, 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 += 1
substrate = substrate[size:]
if length != -1 and len(substrate) < length:
raise error.SubstrateUnderrunError(
'%d-octet short' % (length - len(substrate)))
if length == -1 and not self.supportIndefLength:
error.PyAsn1Error(
'Indefinite length encoding not supported by this codec'
)
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(' %s -> %s' %
(t, v.__class__.__name__))
if asn1Spec.getNegMap():
debug.logger('but neither of: ')
for t, v in asn1Spec.getNegMap().items():
debug.logger(' %s -> %s' %
(t, v.__class__.__name__))
debug.logger(
'new candidate ASN.1 spec is %s, chosen by %s' %
(__chosenSpec is None and '<none>'
or __chosenSpec.prettyPrintType(), 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 %s' % (baseTagSet, ))
else:
concreteDecoder = None
if concreteDecoder:
asn1Spec = __chosenSpec
state = stDecodeValue
else:
state = stTryAsExplicitTag
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
def substrateFun(a, b, c):
return 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('%s not in asn1Spec: %s' %
(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
def test_isOctetsType(self):
assert octets.isOctetsType('abc') == True
assert octets.isOctetsType(123) == False
assert octets.isOctetsType(unicode('abc')) == False
def test_isOctetsType(self):
assert octets.isOctetsType('abc') == False
assert octets.isOctetsType(123) == False
assert octets.isOctetsType(bytes()) == True
def prettyIn(self, value): # override asn1 type method
"""Implements DISPLAY-HINT parsing into base SNMP value
Proper parsing seems impossible due to ambiguities.
Here we are trying to do our best, but be prepared
for failures on complicated DISPLAY-HINTs.
Keep in mind that this parser only works with "text"
input meaning `unicode` (Py2) or `str` (Py3).
"""
for base in inspect.getmro(self.__class__):
if not issubclass(base, TextualConvention) and issubclass(base, Asn1Item):
break
else:
raise SmiError('TEXTUAL-CONVENTION has no underlying SNMP base type')
if self.displayHint and (self.__integer.isSuperTypeOf(self, matchConstraints=False) and
self.getNamedValues() or
self.__unsigned32.isSuperTypeOf(self, matchConstraints=False) or
self.__timeticks.isSuperTypeOf(self, matchConstraints=False)):
value = str(value)
_ = lambda t, f=0: (t, f)
displayHintType, decimalPrecision = _(*self.displayHint.split('-'))
if displayHintType == 'x' and (value.startswith('0x') or value.startswith('-0x')):
try:
if value.startswith('-'):
return base.prettyIn(self, -int(value[3:], 16))
else:
return base.prettyIn(self, int(value[2:], 16))
except Exception as exc:
raise SmiError(
'integer evaluation error: %s' % exc
)
elif displayHintType == 'd':
try:
return base.prettyIn(self, int(float(value) * 10**int(decimalPrecision)))
except Exception as exc:
raise SmiError(
'float evaluation error: %s' % exc
)
elif displayHintType == 'o' and (value.startswith('0') or value.startswith('-0')):
try:
return base.prettyIn(self, int(value, 8))
except Exception as exc:
raise SmiError(
'octal evaluation error: %s' % exc
)
elif displayHintType == 'b' and (value.startswith('B') or value.startswith('-B')):
negative = value.startswith('-')
if negative:
value = value[2:]
else:
value = value[1:]
value = [x != '0' and 1 or 0 for x in value]
binValue = 0
while value:
binValue <<= value[0]
del value[0]
return base.prettyIn(self, binValue)
else:
raise SmiError(
'Unsupported numeric type spec "%s" at %s' % (displayHintType, self.__class__.__name__)
)
elif self.displayHint and self.__octetString.isSuperTypeOf(self, matchConstraints=False):
numBase = {
'x': 16,
'd': 10,
'o': 8
}
numDigits = {
'x': octets.str2octs(string.hexdigits),
'o': octets.str2octs(string.octdigits),
'd': octets.str2octs(string.digits)
}
# how do we know if object is initialized with display-hint
# formatted text? based on "text" input maybe?
# That boils down to `str` object on Py3 or `unicode` on Py2.
if octets.isStringType(value) and not octets.isOctetsType(value):
value = base.prettyIn(self, value)
else:
return base.prettyIn(self, value)
outputValue = octets.str2octs('')
runningValue = value
displayHint = self.displayHint
while runningValue and displayHint:
# 1 this information is totally lost, just fail explicitly
if displayHint[0] == '*':
raise SmiError(
'Can\'t parse "*" in DISPLAY-HINT (%s)' % self.__class__.__name__
)
# 2 this becomes ambiguous when it comes to rendered value
octetLength = ''
while displayHint and displayHint[0] in string.digits:
octetLength += displayHint[0]
displayHint = displayHint[1:]
# length is mandatory but people ignore that
if not octetLength:
octetLength = len(runningValue)
try:
octetLength = int(octetLength)
except Exception:
raise SmiError(
'Bad octet length: %s' % octetLength
)
if not displayHint:
raise SmiError(
'Short octet length: %s' % self.displayHint
)
# 3
displayFormat = displayHint[0]
displayHint = displayHint[1:]
# 4 this is the lifesaver -- we could use it as an anchor
if displayHint and displayHint[0] not in string.digits and displayHint[0] != '*':
displaySep = displayHint[0]
displayHint = displayHint[1:]
else:
displaySep = ''
# 5 is probably impossible to support
if displayFormat in ('a', 't'):
outputValue += runningValue[:octetLength]
elif displayFormat in numBase:
if displaySep:
guessedOctetLength = runningValue.find(octets.str2octs(displaySep))
if guessedOctetLength == -1:
guessedOctetLength = len(runningValue)
else:
for idx in range(len(runningValue)):
if runningValue[idx] not in numDigits[displayFormat]:
guessedOctetLength = idx
break
else:
guessedOctetLength = len(runningValue)
try:
num = int(octets.octs2str(runningValue[:guessedOctetLength]), numBase[displayFormat])
except Exception as exc:
raise SmiError(
'Display format eval failure: %s: %s'
% (runningValue[:guessedOctetLength], exc)
)
num_as_bytes = []
if num:
while num:
num_as_bytes.append(num & 0xFF)
num >>= 8
else:
num_as_bytes = [0]
while len(num_as_bytes) < octetLength:
num_as_bytes.append(0)
num_as_bytes.reverse()
outputValue += octets.ints2octs(num_as_bytes)
if displaySep:
guessedOctetLength += 1
octetLength = guessedOctetLength
else:
raise SmiError(
'Unsupported display format char: %s' %
displayFormat
)
runningValue = runningValue[octetLength:]
if not displayHint:
displayHint = self.displayHint
return base.prettyIn(self, outputValue)
else:
return base.prettyIn(self, value)