#
# 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
#
from pyasn1 import error
__all__ = ['tagClassUniversal', 'tagClassApplication', 'tagClassContext',
'tagClassPrivate', 'tagFormatSimple', 'tagFormatConstructed',
'tagCategoryImplicit', 'tagCategoryExplicit',
'tagCategoryUntagged', 'Tag', 'TagSet']
#: Identifier for ASN.1 class UNIVERSAL
tagClassUniversal = 0x00
#: Identifier for ASN.1 class APPLICATION
tagClassApplication = 0x40
#: Identifier for ASN.1 class context-specific
tagClassContext = 0x80
#: Identifier for ASN.1 class private
tagClassPrivate = 0xC0
#: Identifier for "simple" ASN.1 structure (e.g. scalar)
tagFormatSimple = 0x00
#: Identifier for "constructed" ASN.1 structure (e.g. may have inner components)
tagFormatConstructed = 0x20
tagCategoryImplicit = 0x01
tagCategoryExplicit = 0x02
tagCategoryUntagged = 0x04
class Tag(object):
"""Create ASN.1 tag
Represents ASN.1 tag that can be attached to a ASN.1 type to make
types distinguishable from each other.
*Tag* objects are immutable and duck-type Python :class:`tuple` objects
holding three integer components of a tag.
Parameters
----------
tagClass: :py:class:`int`
Tag *class* value
tagFormat: :py:class:`int`
Tag *format* value
tagId: :py:class:`int`
Tag ID value
"""
def __init__(self, tagClass, tagFormat, tagId):
if tagId < 0:
raise error.PyAsn1Error('Negative tag ID (%s) not allowed' % tagId)
self.__tagClass = tagClass
self.__tagFormat = tagFormat
self.__tagId = tagId
self.__tagClassId = tagClass, tagId
self.__hash = hash(self.__tagClassId)
def __repr__(self):
representation = '[%s:%s:%s]' % (
self.__tagClass, self.__tagFormat, self.__tagId)
return '<%s object, tag %s>' % (
self.__class__.__name__, representation)
def __eq__(self, other):
return self.__tagClassId == other
def __ne__(self, other):
return self.__tagClassId != other
def __lt__(self, other):
return self.__tagClassId < other
def __le__(self, other):
return self.__tagClassId <= other
def __gt__(self, other):
return self.__tagClassId > other
def __ge__(self, other):
return self.__tagClassId >= other
def __hash__(self):
return self.__hash
def __getitem__(self, idx):
if idx == 0:
return self.__tagClass
elif idx == 1:
return self.__tagFormat
elif idx == 2:
return self.__tagId
else:
raise IndexError()
def __iter__(self):
yield self.__tagClass
yield self.__tagFormat
yield self.__tagId
def __and__(self, otherTag):
return self.__class__(self.__tagClass & otherTag.tagClass,
self.__tagFormat & otherTag.tagFormat,
self.__tagId & otherTag.tagId)
def __or__(self, otherTag):
return self.__class__(self.__tagClass | otherTag.tagClass,
self.__tagFormat | otherTag.tagFormat,
self.__tagId | otherTag.tagId)
@property
def tagClass(self):
"""ASN.1 tag class
Returns
-------
: :py:class:`int`
Tag class
"""
return self.__tagClass
@property
def tagFormat(self):
"""ASN.1 tag format
Returns
-------
: :py:class:`int`
Tag format
"""
return self.__tagFormat
@property
def tagId(self):
"""ASN.1 tag ID
Returns
-------
: :py:class:`int`
Tag ID
"""
return self.__tagId
class TagSet(object):
"""Create a collection of ASN.1 tags
Represents a combination of :class:`~pyasn1.type.tag.Tag` objects
that can be attached to a ASN.1 type to make types distinguishable
from each other.
*TagSet* objects are immutable and duck-type Python :class:`tuple` objects
holding arbitrary number of :class:`~pyasn1.type.tag.Tag` objects.
Parameters
----------
baseTag: :class:`~pyasn1.type.tag.Tag`
Base *Tag* object. This tag survives IMPLICIT tagging.
*superTags: :class:`~pyasn1.type.tag.Tag`
Additional *Tag* objects taking part in subtyping.
Examples
--------
.. code-block:: python
class OrderNumber(NumericString):
'''
ASN.1 specification
Order-number ::=
[APPLICATION 5] IMPLICIT NumericString
'''
tagSet = NumericString.tagSet.tagImplicitly(
Tag(tagClassApplication, tagFormatSimple, 5)
)
orderNumber = OrderNumber('1234')
"""
def __init__(self, baseTag=(), *superTags):
self.__baseTag = baseTag
self.__superTags = superTags
self.__superTagsClassId = tuple(
[(superTag.tagClass, superTag.tagId) for superTag in superTags]
)
self.__lenOfSuperTags = len(superTags)
self.__hash = hash(self.__superTagsClassId)
def __repr__(self):
representation = '-'.join(['%s:%s:%s' % (x.tagClass, x.tagFormat, x.tagId)
for x in self.__superTags])
if representation:
representation = 'tags ' + representation
else:
representation = 'untagged'
return '<%s object, %s>' % (self.__class__.__name__, representation)
def __add__(self, superTag):
return self.__class__(self.__baseTag, *self.__superTags + (superTag,))
def __radd__(self, superTag):
return self.__class__(self.__baseTag, *(superTag,) + self.__superTags)
def __getitem__(self, i):
if i.__class__ is slice:
return self.__class__(self.__baseTag, *self.__superTags[i])
else:
return self.__superTags[i]
def __eq__(self, other):
return self.__superTagsClassId == other
def __ne__(self, other):
return self.__superTagsClassId != other
def __lt__(self, other):
return self.__superTagsClassId < other
def __le__(self, other):
return self.__superTagsClassId <= other
def __gt__(self, other):
return self.__superTagsClassId > other
def __ge__(self, other):
return self.__superTagsClassId >= other
def __hash__(self):
return self.__hash
def __len__(self):
return self.__lenOfSuperTags
@property
def baseTag(self):
"""Return base ASN.1 tag
Returns
-------
: :class:`~pyasn1.type.tag.Tag`
Base tag of this *TagSet*
"""
return self.__baseTag
@property
def superTags(self):
"""Return ASN.1 tags
Returns
-------
: :py:class:`tuple`
Tuple of :class:`~pyasn1.type.tag.Tag` objects that this *TagSet* contains
"""
return self.__superTags
def tagExplicitly(self, superTag):
"""Return explicitly tagged *TagSet*
Create a new *TagSet* representing callee *TagSet* explicitly tagged
with passed tag(s). With explicit tagging mode, new tags are appended
to existing tag(s).
Parameters
----------
superTag: :class:`~pyasn1.type.tag.Tag`
*Tag* object to tag this *TagSet*
Returns
-------
: :class:`~pyasn1.type.tag.TagSet`
New *TagSet* object
"""
if superTag.tagClass == tagClassUniversal:
raise error.PyAsn1Error("Can't tag with UNIVERSAL class tag")
if superTag.tagFormat != tagFormatConstructed:
superTag = Tag(superTag.tagClass, tagFormatConstructed, superTag.tagId)
return self + superTag
def tagImplicitly(self, superTag):
"""Return implicitly tagged *TagSet*
Create a new *TagSet* representing callee *TagSet* implicitly tagged
with passed tag(s). With implicit tagging mode, new tag(s) replace the
last existing tag.
Parameters
----------
superTag: :class:`~pyasn1.type.tag.Tag`
*Tag* object to tag this *TagSet*
Returns
-------
: :class:`~pyasn1.type.tag.TagSet`
New *TagSet* object
"""
if self.__superTags:
superTag = Tag(superTag.tagClass, self.__superTags[-1].tagFormat, superTag.tagId)
return self[:-1] + superTag
def isSuperTagSetOf(self, tagSet):
"""Test type relationship against given *TagSet*
The callee is considered to be a supertype of given *TagSet*
tag-wise if all tags in *TagSet* are present in the callee and
they are in the same order.
Parameters
----------
tagSet: :class:`~pyasn1.type.tag.TagSet`
*TagSet* object to evaluate against the callee
Returns
-------
: :py:class:`bool`
:obj:`True` if callee is a supertype of *tagSet*
"""
if len(tagSet) < self.__lenOfSuperTags:
return False
return self.__superTags == tagSet[:self.__lenOfSuperTags]
# Backward compatibility
def getBaseTag(self):
return self.__baseTag
def initTagSet(tag):
return TagSet(tag, tag)