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#
# This file is part of pyasn1 software.
#
# Copyright (c) 2005-2019, Ilya Etingof <[email protected]>
# License: http://snmplabs.com/pyasn1/license.html
#
import sys
from pyasn1 import debug
from pyasn1 import error
from pyasn1.codec.ber import eoo
from pyasn1.compat.integer import to_bytes
from pyasn1.compat.octets import (int2oct, oct2int, ints2octs, null,
str2octs, isOctetsType)
from pyasn1.type import char
from pyasn1.type import tag
from pyasn1.type import univ
from pyasn1.type import useful
__all__ = ['encode']
LOG = debug.registerLoggee(__name__, flags=debug.DEBUG_ENCODER)
class AbstractItemEncoder(object):
supportIndefLenMode = True
# An outcome of otherwise legit call `encodeFun(eoo.endOfOctets)`
eooIntegerSubstrate = (0, 0)
eooOctetsSubstrate = ints2octs(eooIntegerSubstrate)
# noinspection PyMethodMayBeStatic
def encodeTag(self, singleTag, isConstructed):
tagClass, tagFormat, tagId = singleTag
encodedTag = tagClass | tagFormat
if isConstructed:
encodedTag |= tag.tagFormatConstructed
if tagId < 31:
return encodedTag | tagId,
else:
substrate = tagId & 0x7f,
tagId >>= 7
while tagId:
substrate = (0x80 | (tagId & 0x7f),) + substrate
tagId >>= 7
return (encodedTag | 0x1F,) + substrate
def encodeLength(self, length, defMode):
if not defMode and self.supportIndefLenMode:
return (0x80,)
if length < 0x80:
return length,
else:
substrate = ()
while length:
substrate = (length & 0xff,) + substrate
length >>= 8
substrateLen = len(substrate)
if substrateLen > 126:
raise error.PyAsn1Error('Length octets overflow (%d)' % substrateLen)
return (0x80 | substrateLen,) + substrate
def encodeValue(self, value, asn1Spec, encodeFun, **options):
raise error.PyAsn1Error('Not implemented')
def encode(self, value, asn1Spec=None, encodeFun=None, **options):
if asn1Spec is None:
tagSet = value.tagSet
else:
tagSet = asn1Spec.tagSet
# untagged item?
if not tagSet:
substrate, isConstructed, isOctets = self.encodeValue(
value, asn1Spec, encodeFun, **options
)
return substrate
defMode = options.get('defMode', True)
substrate = null
for idx, singleTag in enumerate(tagSet.superTags):
defModeOverride = defMode
# base tag?
if not idx:
try:
substrate, isConstructed, isOctets = self.encodeValue(
value, asn1Spec, encodeFun, **options
)
except error.PyAsn1Error:
exc = sys.exc_info()
raise error.PyAsn1Error(
'Error encoding %r: %s' % (value, exc[1]))
if LOG:
LOG('encoded %svalue %s into %s' % (
isConstructed and 'constructed ' or '', value, substrate
))
if not substrate and isConstructed and options.get('ifNotEmpty', False):
return substrate
if not isConstructed:
defModeOverride = True
if LOG:
LOG('overridden encoding mode into definitive for primitive type')
header = self.encodeTag(singleTag, isConstructed)
if LOG:
LOG('encoded %stag %s into %s' % (
isConstructed and 'constructed ' or '',
singleTag, debug.hexdump(ints2octs(header))))
header += self.encodeLength(len(substrate), defModeOverride)
if LOG:
LOG('encoded %s octets (tag + payload) into %s' % (
len(substrate), debug.hexdump(ints2octs(header))))
if isOctets:
substrate = ints2octs(header) + substrate
if not defModeOverride:
substrate += self.eooOctetsSubstrate
else:
substrate = header + substrate
if not defModeOverride:
substrate += self.eooIntegerSubstrate
if not isOctets:
substrate = ints2octs(substrate)
return substrate
class EndOfOctetsEncoder(AbstractItemEncoder):
def encodeValue(self, value, asn1Spec, encodeFun, **options):
return null, False, True
class BooleanEncoder(AbstractItemEncoder):
supportIndefLenMode = False
def encodeValue(self, value, asn1Spec, encodeFun, **options):
return value and (1,) or (0,), False, False
class IntegerEncoder(AbstractItemEncoder):
supportIndefLenMode = False
supportCompactZero = False
def encodeValue(self, value, asn1Spec, encodeFun, **options):
if value == 0:
if LOG:
LOG('encoding %spayload for zero INTEGER' % (
self.supportCompactZero and 'no ' or ''
))
# de-facto way to encode zero
if self.supportCompactZero:
return (), False, False
else:
return (0,), False, False
return to_bytes(int(value), signed=True), False, True
class BitStringEncoder(AbstractItemEncoder):
def encodeValue(self, value, asn1Spec, encodeFun, **options):
if asn1Spec is not None:
# TODO: try to avoid ASN.1 schema instantiation
value = asn1Spec.clone(value)
valueLength = len(value)
if valueLength % 8:
alignedValue = value << (8 - valueLength % 8)
else:
alignedValue = value
maxChunkSize = options.get('maxChunkSize', 0)
if not maxChunkSize or len(alignedValue) <= maxChunkSize * 8:
substrate = alignedValue.asOctets()
return int2oct(len(substrate) * 8 - valueLength) + substrate, False, True
if LOG:
LOG('encoding into up to %s-octet chunks' % maxChunkSize)
baseTag = value.tagSet.baseTag
# strip off explicit tags
if baseTag:
tagSet = tag.TagSet(baseTag, baseTag)
else:
tagSet = tag.TagSet()
alignedValue = alignedValue.clone(tagSet=tagSet)
stop = 0
substrate = null
while stop < valueLength:
start = stop
stop = min(start + maxChunkSize * 8, valueLength)
substrate += encodeFun(alignedValue[start:stop], asn1Spec, **options)
return substrate, True, True
class OctetStringEncoder(AbstractItemEncoder):
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
class NullEncoder(AbstractItemEncoder):
supportIndefLenMode = False
def encodeValue(self, value, asn1Spec, encodeFun, **options):
return null, False, True
class ObjectIdentifierEncoder(AbstractItemEncoder):
supportIndefLenMode = False
def encodeValue(self, value, asn1Spec, encodeFun, **options):
if asn1Spec is not None:
value = asn1Spec.clone(value)
oid = value.asTuple()
# Build the first pair
try:
first = oid[0]
second = oid[1]
except IndexError:
raise error.PyAsn1Error('Short OID %s' % (value,))
if 0 <= second <= 39:
if first == 1:
oid = (second + 40,) + oid[2:]
elif first == 0:
oid = (second,) + oid[2:]
elif first == 2:
oid = (second + 80,) + oid[2:]
else:
raise error.PyAsn1Error('Impossible first/second arcs at %s' % (value,))
elif first == 2:
oid = (second + 80,) + oid[2:]
else:
raise error.PyAsn1Error('Impossible first/second arcs at %s' % (value,))
octets = ()
# Cycle through subIds
for subOid in oid:
if 0 <= subOid <= 127:
# Optimize for the common case
octets += (subOid,)
elif subOid > 127:
# Pack large Sub-Object IDs
res = (subOid & 0x7f,)
subOid >>= 7
while subOid:
res = (0x80 | (subOid & 0x7f),) + res
subOid >>= 7
# Add packed Sub-Object ID to resulted Object ID
octets += res
else:
raise error.PyAsn1Error('Negative OID arc %s at %s' % (subOid, value))
return octets, False, False
class RealEncoder(AbstractItemEncoder):
supportIndefLenMode = 0
binEncBase = 2 # set to None to choose encoding base automatically
@staticmethod
def _dropFloatingPoint(m, encbase, e):
ms, es = 1, 1
if m < 0:
ms = -1 # mantissa sign
if e < 0:
es = -1 # exponent sign
m *= ms
if encbase == 8:
m *= 2 ** (abs(e) % 3 * es)
e = abs(e) // 3 * es
elif encbase == 16:
m *= 2 ** (abs(e) % 4 * es)
e = abs(e) // 4 * es
while True:
if int(m) != m:
m *= encbase
e -= 1
continue
break
return ms, int(m), encbase, e
def _chooseEncBase(self, value):
m, b, e = value
encBase = [2, 8, 16]
if value.binEncBase in encBase:
return self._dropFloatingPoint(m, value.binEncBase, e)
elif self.binEncBase in encBase:
return self._dropFloatingPoint(m, self.binEncBase, e)
# auto choosing base 2/8/16
mantissa = [m, m, m]
exponent = [e, e, e]
sign = 1
encbase = 2
e = float('inf')
for i in range(3):
(sign,
mantissa[i],
encBase[i],
exponent[i]) = self._dropFloatingPoint(mantissa[i], encBase[i], exponent[i])
if abs(exponent[i]) < abs(e) or (abs(exponent[i]) == abs(e) and mantissa[i] < m):
e = exponent[i]
m = int(mantissa[i])
encbase = encBase[i]
if LOG:
LOG('automatically chosen REAL encoding base %s, sign %s, mantissa %s, '
'exponent %s' % (encbase, sign, m, e))
return sign, m, encbase, e
def encodeValue(self, value, asn1Spec, encodeFun, **options):
if asn1Spec is not None:
value = asn1Spec.clone(value)
if value.isPlusInf:
return (0x40,), False, False
if value.isMinusInf:
return (0x41,), False, False
m, b, e = value
if not m:
return null, False, True
if b == 10:
if LOG:
LOG('encoding REAL into character form')
return str2octs('\x03%dE%s%d' % (m, e == 0 and '+' or '', e)), False, True
elif b == 2:
fo = 0x80 # binary encoding
ms, m, encbase, e = self._chooseEncBase(value)
if ms < 0: # mantissa sign
fo |= 0x40 # sign bit
# exponent & mantissa normalization
if encbase == 2:
while m & 0x1 == 0:
m >>= 1
e += 1
elif encbase == 8:
while m & 0x7 == 0:
m >>= 3
e += 1
fo |= 0x10
else: # encbase = 16
while m & 0xf == 0:
m >>= 4
e += 1
fo |= 0x20
sf = 0 # scale factor
while m & 0x1 == 0:
m >>= 1
sf += 1
if sf > 3:
raise error.PyAsn1Error('Scale factor overflow') # bug if raised
fo |= sf << 2
eo = null
if e == 0 or e == -1:
eo = int2oct(e & 0xff)
else:
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
if e == -1 and eo and not (oct2int(eo[0]) & 0x80):
eo = int2oct(0xff) + 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) + eo
po = null
while m:
po = int2oct(m & 0xff) + po
m >>= 8
substrate = int2oct(fo) + eo + po
return substrate, False, True
else:
raise error.PyAsn1Error('Prohibited Real base %s' % b)
class SequenceEncoder(AbstractItemEncoder):
omitEmptyOptionals = False
# TODO: handling three flavors of input is too much -- split over codecs
def encodeValue(self, value, asn1Spec, encodeFun, **options):
substrate = null
omitEmptyOptionals = options.get(
'omitEmptyOptionals', self.omitEmptyOptionals)
if LOG:
LOG('%sencoding empty OPTIONAL components' % (
omitEmptyOptionals and 'not ' or ''))
if asn1Spec is None:
# instance of ASN.1 schema
inconsistency = value.isInconsistent
if inconsistency:
raise inconsistency
namedTypes = value.componentType
for idx, component in enumerate(value.values()):
if namedTypes:
namedType = namedTypes[idx]
if namedType.isOptional and not component.isValue:
if LOG:
LOG('not encoding OPTIONAL component %r' % (namedType,))
continue
if namedType.isDefaulted and component == namedType.asn1Object:
if LOG:
LOG('not encoding DEFAULT component %r' % (namedType,))
continue
if omitEmptyOptionals:
options.update(ifNotEmpty=namedType.isOptional)
# wrap open type blob if needed
if namedTypes and namedType.openType:
wrapType = namedType.asn1Object
if wrapType.typeId in (
univ.SetOf.typeId, univ.SequenceOf.typeId):
substrate += encodeFun(
component, asn1Spec,
**dict(options, wrapType=wrapType.componentType))
else:
chunk = encodeFun(component, asn1Spec, **options)
if wrapType.isSameTypeWith(component):
substrate += chunk
else:
substrate += encodeFun(chunk, wrapType, **options)
if LOG:
LOG('wrapped with wrap type %r' % (wrapType,))
else:
substrate += encodeFun(component, asn1Spec, **options)
else:
# bare Python value + ASN.1 schema
for idx, namedType in enumerate(asn1Spec.componentType.namedTypes):
try:
component = value[namedType.name]
except KeyError:
raise error.PyAsn1Error('Component name "%s" not found in %r' % (
namedType.name, value))
if namedType.isOptional and namedType.name not in value:
if LOG:
LOG('not encoding OPTIONAL component %r' % (namedType,))
continue
if namedType.isDefaulted and component == namedType.asn1Object:
if LOG:
LOG('not encoding DEFAULT component %r' % (namedType,))
continue
if omitEmptyOptionals:
options.update(ifNotEmpty=namedType.isOptional)
componentSpec = namedType.asn1Object
# wrap open type blob if needed
if namedType.openType:
if componentSpec.typeId in (
univ.SetOf.typeId, univ.SequenceOf.typeId):
substrate += encodeFun(
component, componentSpec,
**dict(options, wrapType=componentSpec.componentType))
else:
chunk = encodeFun(component, componentSpec, **options)
if componentSpec.isSameTypeWith(component):
substrate += chunk
else:
substrate += encodeFun(chunk, componentSpec, **options)
if LOG:
LOG('wrapped with wrap type %r' % (componentSpec,))
else:
substrate += encodeFun(component, componentSpec, **options)
return substrate, True, True
class SequenceOfEncoder(AbstractItemEncoder):
def _encodeComponents(self, value, asn1Spec, encodeFun, **options):
if asn1Spec is None:
inconsistency = value.isInconsistent
if inconsistency:
raise inconsistency
else:
asn1Spec = asn1Spec.componentType
chunks = []
wrapType = options.pop('wrapType', None)
for idx, component in enumerate(value):
chunk = encodeFun(component, asn1Spec, **options)
if (wrapType is not None and
not wrapType.isSameTypeWith(component)):
# wrap encoded value with wrapper container (e.g. ANY)
chunk = encodeFun(chunk, wrapType, **options)
if LOG:
LOG('wrapped with wrap type %r' % (wrapType,))
chunks.append(chunk)
return chunks
def encodeValue(self, value, asn1Spec, encodeFun, **options):
chunks = self._encodeComponents(
value, asn1Spec, encodeFun, **options)
return null.join(chunks), True, True
class ChoiceEncoder(AbstractItemEncoder):
def encodeValue(self, value, asn1Spec, encodeFun, **options):
if asn1Spec is None:
component = value.getComponent()
else:
names = [namedType.name for namedType in asn1Spec.componentType.namedTypes
if namedType.name in value]
if len(names) != 1:
raise error.PyAsn1Error('%s components for Choice at %r' % (len(names) and 'Multiple ' or 'None ', value))
name = names[0]
component = value[name]
asn1Spec = asn1Spec[name]
return encodeFun(component, asn1Spec, **options), True, True
class AnyEncoder(OctetStringEncoder):
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
tagMap = {
eoo.endOfOctets.tagSet: EndOfOctetsEncoder(),
univ.Boolean.tagSet: BooleanEncoder(),
univ.Integer.tagSet: IntegerEncoder(),
univ.BitString.tagSet: BitStringEncoder(),
univ.OctetString.tagSet: OctetStringEncoder(),
univ.Null.tagSet: NullEncoder(),
univ.ObjectIdentifier.tagSet: ObjectIdentifierEncoder(),
univ.Enumerated.tagSet: IntegerEncoder(),
univ.Real.tagSet: RealEncoder(),
# Sequence & Set have same tags as SequenceOf & SetOf
univ.SequenceOf.tagSet: SequenceOfEncoder(),
univ.SetOf.tagSet: SequenceOfEncoder(),
univ.Choice.tagSet: ChoiceEncoder(),
# character string types
char.UTF8String.tagSet: OctetStringEncoder(),
char.NumericString.tagSet: OctetStringEncoder(),
char.PrintableString.tagSet: OctetStringEncoder(),
char.TeletexString.tagSet: OctetStringEncoder(),
char.VideotexString.tagSet: OctetStringEncoder(),
char.IA5String.tagSet: OctetStringEncoder(),
char.GraphicString.tagSet: OctetStringEncoder(),
char.VisibleString.tagSet: OctetStringEncoder(),
char.GeneralString.tagSet: OctetStringEncoder(),
char.UniversalString.tagSet: OctetStringEncoder(),
char.BMPString.tagSet: OctetStringEncoder(),
# useful types
useful.ObjectDescriptor.tagSet: OctetStringEncoder(),
useful.GeneralizedTime.tagSet: OctetStringEncoder(),
useful.UTCTime.tagSet: OctetStringEncoder()
}
# Put in ambiguous & non-ambiguous types for faster codec lookup
typeMap = {
univ.Boolean.typeId: BooleanEncoder(),
univ.Integer.typeId: IntegerEncoder(),
univ.BitString.typeId: BitStringEncoder(),
univ.OctetString.typeId: OctetStringEncoder(),
univ.Null.typeId: NullEncoder(),
univ.ObjectIdentifier.typeId: ObjectIdentifierEncoder(),
univ.Enumerated.typeId: IntegerEncoder(),
univ.Real.typeId: RealEncoder(),
# Sequence & Set have same tags as SequenceOf & SetOf
univ.Set.typeId: SequenceEncoder(),
univ.SetOf.typeId: SequenceOfEncoder(),
univ.Sequence.typeId: SequenceEncoder(),
univ.SequenceOf.typeId: SequenceOfEncoder(),
univ.Choice.typeId: ChoiceEncoder(),
univ.Any.typeId: AnyEncoder(),
# character string types
char.UTF8String.typeId: OctetStringEncoder(),
char.NumericString.typeId: OctetStringEncoder(),
char.PrintableString.typeId: OctetStringEncoder(),
char.TeletexString.typeId: OctetStringEncoder(),
char.VideotexString.typeId: OctetStringEncoder(),
char.IA5String.typeId: OctetStringEncoder(),
char.GraphicString.typeId: OctetStringEncoder(),
char.VisibleString.typeId: OctetStringEncoder(),
char.GeneralString.typeId: OctetStringEncoder(),
char.UniversalString.typeId: OctetStringEncoder(),
char.BMPString.typeId: OctetStringEncoder(),
# useful types
useful.ObjectDescriptor.typeId: OctetStringEncoder(),
useful.GeneralizedTime.typeId: OctetStringEncoder(),
useful.UTCTime.typeId: OctetStringEncoder()
}
class Encoder(object):
fixedDefLengthMode = None
fixedChunkSize = None
# noinspection PyDefaultArgument
def __init__(self, tagMap, typeMap={}):
self.__tagMap = tagMap
self.__typeMap = typeMap
def __call__(self, value, asn1Spec=None, **options):
try:
if asn1Spec is None:
typeId = value.typeId
else:
typeId = asn1Spec.typeId
except AttributeError:
raise error.PyAsn1Error('Value %r is not ASN.1 type instance '
'and "asn1Spec" not given' % (value,))
if LOG:
LOG('encoder called in %sdef mode, chunk size %s for '
'type %s, value:\n%s' % (not options.get('defMode', True) and 'in' or '', options.get('maxChunkSize', 0), asn1Spec is None and value.prettyPrintType() or asn1Spec.prettyPrintType(), value))
if self.fixedDefLengthMode is not None:
options.update(defMode=self.fixedDefLengthMode)
if self.fixedChunkSize is not None:
options.update(maxChunkSize=self.fixedChunkSize)
try:
concreteEncoder = self.__typeMap[typeId]
if LOG:
LOG('using value codec %s chosen by type ID %s' % (concreteEncoder.__class__.__name__, typeId))
except KeyError:
if asn1Spec is None:
tagSet = value.tagSet
else:
tagSet = asn1Spec.tagSet
# use base type for codec lookup to recover untagged types
baseTagSet = tag.TagSet(tagSet.baseTag, tagSet.baseTag)
try:
concreteEncoder = self.__tagMap[baseTagSet]
except KeyError:
raise error.PyAsn1Error('No encoder for %r (%s)' % (value, tagSet))
if LOG:
LOG('using value codec %s chosen by tagSet %s' % (concreteEncoder.__class__.__name__, tagSet))
substrate = concreteEncoder.encode(value, asn1Spec, self, **options)
if LOG:
LOG('codec %s built %s octets of substrate: %s\nencoder completed' % (concreteEncoder, len(substrate), debug.hexdump(substrate)))
return substrate
#: Turns ASN.1 object into BER octet stream.
#:
#: Takes any ASN.1 object (e.g. :py:class:`~pyasn1.type.base.PyAsn1Item` derivative)
#: walks all its components recursively and produces a BER octet stream.
#:
#: Parameters
#: ----------
#: value: either a Python or pyasn1 object (e.g. :py:class:`~pyasn1.type.base.PyAsn1Item` derivative)
#: A Python or pyasn1 object to encode. If Python object is given, `asnSpec`
#: parameter is required to guide the encoding process.
#:
#: Keyword Args
#: ------------
#: asn1Spec:
#: Optional ASN.1 schema or value object e.g. :py:class:`~pyasn1.type.base.PyAsn1Item` derivative
#:
#: defMode: :py:class:`bool`
#: If :obj:`False`, produces indefinite length encoding
#:
#: maxChunkSize: :py:class:`int`
#: Maximum chunk size in chunked encoding mode (0 denotes unlimited chunk size)
#:
#: Returns
#: -------
#: : :py:class:`bytes` (Python 3) or :py:class:`str` (Python 2)
#: Given ASN.1 object encoded into BER octetstream
#:
#: Raises
#: ------
#: ~pyasn1.error.PyAsn1Error
#: On encoding errors
#:
#: Examples
#: --------
#: Encode Python value into BER with ASN.1 schema
#:
#: .. code-block:: pycon
#:
#: >>> seq = SequenceOf(componentType=Integer())
#: >>> encode([1, 2, 3], asn1Spec=seq)
#: b'0\t\x02\x01\x01\x02\x01\x02\x02\x01\x03'
#:
#: Encode ASN.1 value object into BER
#:
#: .. code-block:: pycon
#:
#: >>> seq = SequenceOf(componentType=Integer())
#: >>> seq.extend([1, 2, 3])
#: >>> encode(seq)
#: b'0\t\x02\x01\x01\x02\x01\x02\x02\x01\x03'
#:
encode = Encoder(tagMap, typeMap)
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