X-Git-Url: http://www.git.cypherpunks.ru/?a=blobdiff_plain;f=pyderasn.py;h=5f0c0343ccd0d4153d29e6328fde4a73882229ec;hb=ac86b0fe801de06f9b861579e5d566d3cdb3236b;hp=6435758843b4b9a9ff5fbf67f4b1432d15be0c83;hpb=16f6fd50b698cba058661ceba684237bd82229e4;p=pyderasn.git diff --git a/pyderasn.py b/pyderasn.py index 6435758..5f0c034 100755 --- a/pyderasn.py +++ b/pyderasn.py @@ -1,7 +1,7 @@ #!/usr/bin/env python # coding: utf-8 # PyDERASN -- Python ASN.1 DER/BER codec with abstract structures -# Copyright (C) 2017-2019 Sergey Matveev +# Copyright (C) 2017-2020 Sergey Matveev # # This program is free software: you can redistribute it and/or modify # it under the terms of the GNU Lesser General Public License as @@ -13,8 +13,7 @@ # GNU Lesser General Public License for more details. # # You should have received a copy of the GNU Lesser General Public -# License along with this program. If not, see -# . +# License along with this program. If not, see . """Python ASN.1 DER/BER codec with abstract structures This library allows you to marshal various structures in ASN.1 DER @@ -347,6 +346,8 @@ DEFINED BY some previously met ObjectIdentifier. This library provides ability to specify mapping between some OID and field that must be decoded with specific specification. +.. _defines: + defines kwarg _____________ @@ -420,8 +421,8 @@ value must be sequence of following tuples:: where ``decode_path`` is a tuple holding so-called decode path to the exact :py:class:`pyderasn.ObjectIdentifier` field you want to apply -``defines``, holding exactly the same value as accepted in its keyword -argument. +``defines``, holding exactly the same value as accepted in its +:ref:`keyword argument `. For example, again for CMS, you want to automatically decode ``SignedData`` and CMC's (:rfc:`5272`) ``PKIData`` and ``PKIResponse`` @@ -516,6 +517,11 @@ lengths will be invalid in that case. This option should be used only for skipping some decode errors, just to see the decoded structure somehow. +Base Obj +-------- +.. autoclass:: pyderasn.Obj + :members: + Primitive types --------------- @@ -625,10 +631,10 @@ Various .. autofunction:: pyderasn.tag_decode .. autofunction:: pyderasn.tag_ctxp .. autofunction:: pyderasn.tag_ctxc -.. autoclass:: pyderasn.Obj .. autoclass:: pyderasn.DecodeError :members: __init__ .. autoclass:: pyderasn.NotEnoughData +.. autoclass:: pyderasn.ExceedingData .. autoclass:: pyderasn.LenIndefForm .. autoclass:: pyderasn.TagMismatch .. autoclass:: pyderasn.InvalidLength @@ -672,6 +678,7 @@ except ImportError: # pragma: no cover def colored(what, *args, **kwargs): return what +__version__ = "5.6" __all__ = ( "Any", @@ -683,6 +690,7 @@ __all__ = ( "DecodeError", "DecodePathDefBy", "Enumerated", + "ExceedingData", "GeneralizedTime", "GeneralString", "GraphicString", @@ -793,6 +801,18 @@ class NotEnoughData(DecodeError): pass +class ExceedingData(ASN1Error): + def __init__(self, nbytes): + super(ExceedingData, self).__init__() + self.nbytes = nbytes + + def __str__(self): + return "%d trailing bytes" % self.nbytes + + def __repr__(self): + return "%s(%s)" % (self.__class__.__name__, self) + + class LenIndefForm(DecodeError): pass @@ -1018,9 +1038,9 @@ def len_decode(data): ######################################################################## class AutoAddSlots(type): - def __new__(mcs, name, bases, _dict): + def __new__(cls, name, bases, _dict): _dict["__slots__"] = _dict.get("__slots__", ()) - return type.__new__(mcs, name, bases, _dict) + return type.__new__(cls, name, bases, _dict) @add_metaclass(AutoAddSlots) @@ -1094,10 +1114,14 @@ class Obj(object): @property def tlen(self): + """See :ref:`decoding` + """ return len(self.tag) @property def tlvlen(self): + """See :ref:`decoding` + """ return self.tlen + self.llen + self.vlen def __str__(self): # pragma: no cover @@ -1122,6 +1146,10 @@ class Obj(object): raise NotImplementedError() def encode(self): + """Encode the structure + + :returns: DER representation + """ raw = self._encode() if self._expl is None: return raw @@ -1149,6 +1177,8 @@ class Obj(object): determine if tag satisfies the scheme) :param _ctx_immutable: do we need to copy ``ctx`` before using it :returns: (Obj, remaining data) + + .. seealso:: :ref:`decoding` """ if ctx is None: ctx = {} @@ -1164,7 +1194,7 @@ class Obj(object): tag_only=tag_only, ) if tag_only: - return + return None obj, tail = result else: try: @@ -1202,7 +1232,7 @@ class Obj(object): tag_only=tag_only, ) if tag_only: # pragma: no cover - return + return None obj, tail = result eoc_expected, tail = tail[:EOC_LEN], tail[EOC_LEN:] if eoc_expected.tobytes() != EOC: @@ -1237,7 +1267,7 @@ class Obj(object): tag_only=tag_only, ) if tag_only: # pragma: no cover - return + return None obj, tail = result if obj.tlvlen < l and not ctx.get("allow_expl_oob", False): raise DecodeError( @@ -1248,42 +1278,80 @@ class Obj(object): ) return obj, (tail if leavemm else tail.tobytes()) + def decod(self, data, offset=0, decode_path=(), ctx=None): + """Decode the data, check that tail is empty + + :raises ExceedingData: if tail is not empty + + This is just a wrapper over :py:meth:`pyderasn.Obj.decode` + (decode without tail) that also checks that there is no + trailing data left. + """ + obj, tail = self.decode( + data, + offset=offset, + decode_path=decode_path, + ctx=ctx, + leavemm=True, + ) + if len(tail) > 0: + raise ExceedingData(len(tail)) + return obj + @property def expled(self): + """See :ref:`decoding` + """ return self._expl is not None @property def expl_tag(self): + """See :ref:`decoding` + """ return self._expl @property def expl_tlen(self): + """See :ref:`decoding` + """ return len(self._expl) @property def expl_llen(self): + """See :ref:`decoding` + """ if self.expl_lenindef: return 1 return len(len_encode(self.tlvlen)) @property def expl_offset(self): + """See :ref:`decoding` + """ return self.offset - self.expl_tlen - self.expl_llen @property def expl_vlen(self): + """See :ref:`decoding` + """ return self.tlvlen @property def expl_tlvlen(self): + """See :ref:`decoding` + """ return self.expl_tlen + self.expl_llen + self.expl_vlen @property def fulloffset(self): + """See :ref:`decoding` + """ return self.expl_offset if self.expled else self.offset @property def fulllen(self): + """See :ref:`decoding` + """ return self.expl_tlvlen if self.expled else self.tlvlen def pps_lenindef(self, decode_path): @@ -1746,7 +1814,7 @@ class Boolean(Obj): offset=offset, ) if tag_only: - return + return None try: l, _, v = len_decode(lv) except DecodeError as err: @@ -1976,6 +2044,7 @@ class Integer(Obj): for name, value in iteritems(self.specs): if value == self._value: return name + return None def __call__( self, @@ -2055,7 +2124,7 @@ class Integer(Obj): offset=offset, ) if tag_only: - return + return None try: l, llen, v = len_decode(lv) except DecodeError as err: @@ -2275,7 +2344,7 @@ class BitString(Obj): if not frozenset(value) <= SET01: raise ValueError("B's coding contains unacceptable chars") return self._bits2octets(value) - elif value.endswith("'H"): + if value.endswith("'H"): value = value[1:-2] return ( len(value) * 4, @@ -2283,8 +2352,7 @@ class BitString(Obj): ) if isinstance(value, binary_type): return (len(value) * 8, value) - else: - raise InvalidValueType((self.__class__, string_types, binary_type)) + raise InvalidValueType((self.__class__, string_types, binary_type)) if isinstance(value, tuple): if ( len(value) == 2 and @@ -2403,7 +2471,7 @@ class BitString(Obj): octets, )) - def _decode_chunk(self, lv, offset, decode_path, ctx): + def _decode_chunk(self, lv, offset, decode_path): try: l, llen, v = len_decode(lv) except DecodeError as err: @@ -2473,8 +2541,8 @@ class BitString(Obj): ) if t == self.tag: if tag_only: # pragma: no cover - return - return self._decode_chunk(lv, offset, decode_path, ctx) + return None + return self._decode_chunk(lv, offset, decode_path) if t == self.tag_constructed: if not ctx.get("bered", False): raise DecodeError( @@ -2484,7 +2552,7 @@ class BitString(Obj): offset=offset, ) if tag_only: # pragma: no cover - return + return None lenindef = False try: l, llen, v = len_decode(lv) @@ -2793,7 +2861,7 @@ class OctetString(Obj): self._value, )) - def _decode_chunk(self, lv, offset, decode_path, ctx): + def _decode_chunk(self, lv, offset, decode_path): try: l, llen, v = len_decode(lv) except DecodeError as err: @@ -2849,8 +2917,8 @@ class OctetString(Obj): ) if t == self.tag: if tag_only: - return - return self._decode_chunk(lv, offset, decode_path, ctx) + return None + return self._decode_chunk(lv, offset, decode_path) if t == self.tag_constructed: if not ctx.get("bered", False): raise DecodeError( @@ -2860,7 +2928,7 @@ class OctetString(Obj): offset=offset, ) if tag_only: - return + return None lenindef = False try: l, llen, v = len_decode(lv) @@ -3076,7 +3144,7 @@ class Null(Obj): offset=offset, ) if tag_only: # pragma: no cover - return + return None try: l, _, v = len_decode(lv) except DecodeError as err: @@ -3331,7 +3399,7 @@ class ObjectIdentifier(Obj): offset=offset, ) if tag_only: # pragma: no cover - return + return None try: l, llen, v = len_decode(lv) except DecodeError as err: @@ -4249,7 +4317,7 @@ class Choice(Obj): offset=offset, ) if tag_only: # pragma: no cover - return + return None value, tail = spec.decode( tlv, offset=offset, @@ -4718,9 +4786,8 @@ class Sequence(Obj): if spec.optional: continue return False - else: - if not value.ready: - return False + if not value.ready: + return False return True @property @@ -4832,7 +4899,7 @@ class Sequence(Obj): offset=offset, ) if tag_only: # pragma: no cover - return + return None lenindef = False ctx_bered = ctx.get("bered", False) try: @@ -4884,8 +4951,8 @@ class Sequence(Obj): ctx=ctx, _ctx_immutable=False, ) - except TagMismatch: - if spec.optional: + except TagMismatch as err: + if (len(err.decode_path) == len(decode_path) + 1) and spec.optional: continue raise @@ -5082,7 +5149,7 @@ class Set(Sequence): offset=offset, ) if tag_only: - return + return None lenindef = False ctx_bered = ctx.get("bered", False) try: @@ -5415,7 +5482,7 @@ class SequenceOf(Obj): offset=offset, ) if tag_only: - return + return None lenindef = False ctx_bered = ctx.get("bered", False) try: @@ -5719,7 +5786,7 @@ def main(): # pragma: no cover print(pprinter( obj, oid_maps=oid_maps, - with_colours=True if environ.get("NO_COLOR") is None else False, + with_colours=environ.get("NO_COLOR") is None, with_decode_path=args.print_decode_path, decode_path_only=( () if args.decode_path_only is None else