]> Cypherpunks.ru repositories - pyderasn.git/blobdiff - pyderasn.py
Explicit mention that *Time do not support BER
[pyderasn.git] / pyderasn.py
index 4a9684fc0b9a6a9e000764fbbca938e223640f4b..c83b4393037e180c943c6e72decb9509b188a097 100755 (executable)
@@ -1,7 +1,7 @@
 #!/usr/bin/env python
 # coding: utf-8
 # PyDERASN -- Python ASN.1 DER/BER codec with abstract structures
-# Copyright (C) 2017-2018 Sergey Matveev <stargrave@stargrave.org>
+# Copyright (C) 2017-2019 Sergey Matveev <stargrave@stargrave.org>
 #
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU Lesser General Public License as
@@ -384,7 +384,8 @@ constructed primitive types should be parsed successfully.
 
 * If object is encoded in BER form (not the DER one), then ``ber_encoded``
   attribute is set to True. Only ``BOOLEAN``, ``BIT STRING``, ``OCTET
-  STRING``, ``SEQUENCE``, ``SET``, ``SET OF`` can contain it.
+  STRING``, ``OBJECT IDENTIFIER``, ``SEQUENCE``, ``SET``, ``SET OF``
+  can contain it.
 * If object has an indefinite length encoding, then its ``lenindef``
   attribute is set to True. Only ``BIT STRING``, ``OCTET STRING``,
   ``SEQUENCE``, ``SET``, ``SEQUENCE OF``, ``SET OF``, ``ANY`` can
@@ -515,6 +516,7 @@ Various
 -------
 
 .. autofunction:: pyderasn.abs_decode_path
+.. autofunction:: pyderasn.colonize_hex
 .. autofunction:: pyderasn.hexenc
 .. autofunction:: pyderasn.hexdec
 .. autofunction:: pyderasn.tag_encode
@@ -539,6 +541,7 @@ from codecs import getdecoder
 from codecs import getencoder
 from collections import namedtuple
 from collections import OrderedDict
+from copy import copy
 from datetime import datetime
 from math import ceil
 from os import environ
@@ -552,6 +555,8 @@ from six import indexbytes
 from six import int2byte
 from six import integer_types
 from six import iterbytes
+from six import iteritems
+from six import itervalues
 from six import PY2
 from six import string_types
 from six import text_type
@@ -646,6 +651,7 @@ LENINDEF_PP_CHAR = "I" if PY2 else "∞"
 class ASN1Error(ValueError):
     pass
 
+
 class DecodeError(ASN1Error):
     def __init__(self, msg="", klass=None, decode_path=(), offset=0):
         """
@@ -1027,6 +1033,7 @@ class Obj(object):
             decode_path=(),
             ctx=None,
             tag_only=False,
+            _ctx_immutable=True,
     ):
         """Decode the data
 
@@ -1034,14 +1041,17 @@ class Obj(object):
         :param int offset: initial data's offset
         :param bool leavemm: do we need to leave memoryview of remaining
                     data as is, or convert it to bytes otherwise
-        :param ctx: optional :ref:`context <ctx>` governing decoding process.
+        :param ctx: optional :ref:`context <ctx>` governing decoding process
         :param tag_only: decode only the tag, without length and contents
                          (used only in Choice and Set structures, trying to
                          determine if tag satisfies the scheme)
+        :param _ctx_immutable: do we need to copy ``ctx`` before using it
         :returns: (Obj, remaining data)
         """
         if ctx is None:
             ctx = {}
+        elif _ctx_immutable:
+            ctx = copy(ctx)
         tlv = memoryview(data)
         if self._expl is None:
             result = self._decode(
@@ -1235,6 +1245,7 @@ class DecodePathDefBy(object):
 ########################################################################
 
 PP = namedtuple("PP", (
+    "obj",
     "asn1_type_name",
     "obj_name",
     "decode_path",
@@ -1260,6 +1271,7 @@ PP = namedtuple("PP", (
 
 
 def _pp(
+        obj=None,
         asn1_type_name="unknown",
         obj_name="unknown",
         decode_path=(),
@@ -1283,6 +1295,7 @@ def _pp(
         bered=False,
 ):
     return PP(
+        obj,
         asn1_type_name,
         obj_name,
         decode_path,
@@ -1311,6 +1324,12 @@ def _colourize(what, colour, with_colours, attrs=("bold",)):
     return colored(what, colour, attrs=attrs) if with_colours else what
 
 
+def colonize_hex(hexed):
+    """Separate hexadecimal string with colons
+    """
+    return ":".join(hexed[i:i + 2] for i in six_xrange(0, len(hexed), 2))
+
+
 def pp_console_row(
         pp,
         oids=None,
@@ -1381,6 +1400,15 @@ def pp_console_row(
                 value in oids
         ):
             cols.append(_colourize("(%s)" % oids[value], "green", with_colours))
+        if pp.asn1_type_name == Integer.asn1_type_name:
+            hex_repr = hex(int(pp.obj._value))[2:].upper()
+            if len(hex_repr) % 2 != 0:
+                hex_repr = "0" + hex_repr
+            cols.append(_colourize(
+                "(%s)" % colonize_hex(hex_repr),
+                "green",
+                with_colours,
+            ))
     if with_blob:
         if isinstance(pp.blob, binary_type):
             cols.append(hexenc(pp.blob))
@@ -1406,11 +1434,9 @@ def pp_console_blob(pp, decode_path_len_decrease=0):
         cols.append(" ." * (decode_path_len + 1))
     if isinstance(pp.blob, binary_type):
         blob = hexenc(pp.blob).upper()
-        for i in range(0, len(blob), 32):
+        for i in six_xrange(0, len(blob), 32):
             chunk = blob[i:i + 32]
-            yield " ".join(cols + [":".join(
-                chunk[j:j + 2] for j in range(0, len(chunk), 2)
-            )])
+            yield " ".join(cols + [colonize_hex(chunk)])
     elif isinstance(pp.blob, tuple):
         yield " ".join(cols + [", ".join(pp.blob)])
 
@@ -1525,10 +1551,10 @@ class Boolean(Obj):
                 self._value = default
 
     def _value_sanitize(self, value):
-        if issubclass(value.__class__, Boolean):
-            return value._value
         if isinstance(value, bool):
             return value
+        if issubclass(value.__class__, Boolean):
+            return value._value
         raise InvalidValueType((self.__class__, bool))
 
     @property
@@ -1545,6 +1571,9 @@ class Boolean(Obj):
         obj.offset = self.offset
         obj.llen = self.llen
         obj.vlen = self.vlen
+        obj.expl_lenindef = self.expl_lenindef
+        obj.lenindef = self.lenindef
+        obj.ber_encoded = self.ber_encoded
         return obj
 
     def __nonzero__(self):
@@ -1663,6 +1692,7 @@ class Boolean(Obj):
 
     def pps(self, decode_path=()):
         yield _pp(
+            obj=self,
             asn1_type_name=self.asn1_type_name,
             obj_name=self.__class__.__name__,
             decode_path=decode_path,
@@ -1770,10 +1800,10 @@ class Integer(Obj):
                 self._value = default
 
     def _value_sanitize(self, value):
-        if issubclass(value.__class__, Integer):
-            value = value._value
-        elif isinstance(value, integer_types):
+        if isinstance(value, integer_types):
             pass
+        elif issubclass(value.__class__, Integer):
+            value = value._value
         elif isinstance(value, str):
             value = self.specs.get(value)
             if value is None:
@@ -1800,6 +1830,9 @@ class Integer(Obj):
         obj.offset = self.offset
         obj.llen = self.llen
         obj.vlen = self.vlen
+        obj.expl_lenindef = self.expl_lenindef
+        obj.lenindef = self.lenindef
+        obj.ber_encoded = self.ber_encoded
         return obj
 
     def __int__(self):
@@ -1830,7 +1863,7 @@ class Integer(Obj):
 
     @property
     def named(self):
-        for name, value in self.specs.items():
+        for name, value in iteritems(self.specs):
             if value == self._value:
                 return name
 
@@ -1990,6 +2023,7 @@ class Integer(Obj):
 
     def pps(self, decode_path=()):
         yield _pp(
+            obj=self,
             asn1_type_name=self.asn1_type_name,
             obj_name=self.__class__.__name__,
             decode_path=decode_path,
@@ -2013,6 +2047,9 @@ class Integer(Obj):
             yield pp
 
 
+SET01 = frozenset(("0", "1"))
+
+
 class BitString(Obj):
     """``BIT STRING`` bit string type
 
@@ -2118,8 +2155,6 @@ class BitString(Obj):
         return bit_len, bytes(octets)
 
     def _value_sanitize(self, value):
-        if issubclass(value.__class__, BitString):
-            return value._value
         if isinstance(value, (string_types, binary_type)):
             if (
                     isinstance(value, string_types) and
@@ -2127,7 +2162,7 @@ class BitString(Obj):
             ):
                 if value.endswith("'B"):
                     value = value[1:-2]
-                    if not set(value) <= set(("0", "1")):
+                    if not frozenset(value) <= SET01:
                         raise ValueError("B's coding contains unacceptable chars")
                     return self._bits2octets(value)
                 elif value.endswith("'H"):
@@ -2155,11 +2190,13 @@ class BitString(Obj):
                 bits.append(bit)
             if len(bits) == 0:
                 return self._bits2octets("")
-            bits = set(bits)
+            bits = frozenset(bits)
             return self._bits2octets("".join(
                 ("1" if bit in bits else "0")
                 for bit in six_xrange(max(bits) + 1)
             ))
+        if issubclass(value.__class__, BitString):
+            return value._value
         raise InvalidValueType((self.__class__, binary_type, string_types))
 
     @property
@@ -2179,6 +2216,9 @@ class BitString(Obj):
         obj.offset = self.offset
         obj.llen = self.llen
         obj.vlen = self.vlen
+        obj.expl_lenindef = self.expl_lenindef
+        obj.lenindef = self.lenindef
+        obj.ber_encoded = self.ber_encoded
         return obj
 
     def __iter__(self):
@@ -2208,7 +2248,7 @@ class BitString(Obj):
 
     @property
     def named(self):
-        return [name for name, bit in self.specs.items() if self[bit]]
+        return [name for name, bit in iteritems(self.specs) if self[bit]]
 
     def __call__(
             self,
@@ -2387,6 +2427,7 @@ class BitString(Obj):
                         decode_path=sub_decode_path,
                         leavemm=True,
                         ctx=ctx,
+                        _ctx_immutable=False,
                     )
                 except TagMismatch:
                     raise DecodeError(
@@ -2451,6 +2492,7 @@ class BitString(Obj):
             if len(self.specs) > 0:
                 blob = tuple(self.named)
         yield _pp(
+            obj=self,
             asn1_type_name=self.asn1_type_name,
             obj_name=self.__class__.__name__,
             decode_path=decode_path,
@@ -2563,10 +2605,10 @@ class OctetString(Obj):
         )
 
     def _value_sanitize(self, value):
-        if issubclass(value.__class__, OctetString):
-            value = value._value
-        elif isinstance(value, binary_type):
+        if isinstance(value, binary_type):
             pass
+        elif issubclass(value.__class__, OctetString):
+            value = value._value
         else:
             raise InvalidValueType((self.__class__, bytes))
         if not self._bound_min <= len(value) <= self._bound_max:
@@ -2589,6 +2631,9 @@ class OctetString(Obj):
         obj.offset = self.offset
         obj.llen = self.llen
         obj.vlen = self.vlen
+        obj.expl_lenindef = self.expl_lenindef
+        obj.lenindef = self.lenindef
+        obj.ber_encoded = self.ber_encoded
         return obj
 
     def __bytes__(self):
@@ -2751,6 +2796,7 @@ class OctetString(Obj):
                         decode_path=sub_decode_path,
                         leavemm=True,
                         ctx=ctx,
+                        _ctx_immutable=False,
                     )
                 except TagMismatch:
                     raise DecodeError(
@@ -2801,6 +2847,7 @@ class OctetString(Obj):
 
     def pps(self, decode_path=()):
         yield _pp(
+            obj=self,
             asn1_type_name=self.asn1_type_name,
             obj_name=self.__class__.__name__,
             decode_path=decode_path,
@@ -2873,6 +2920,9 @@ class Null(Obj):
         obj.offset = self.offset
         obj.llen = self.llen
         obj.vlen = self.vlen
+        obj.expl_lenindef = self.expl_lenindef
+        obj.lenindef = self.lenindef
+        obj.ber_encoded = self.ber_encoded
         return obj
 
     def __eq__(self, their):
@@ -2946,6 +2996,7 @@ class Null(Obj):
 
     def pps(self, decode_path=()):
         yield _pp(
+            obj=self,
             asn1_type_name=self.asn1_type_name,
             obj_name=self.__class__.__name__,
             decode_path=decode_path,
@@ -3082,6 +3133,9 @@ class ObjectIdentifier(Obj):
         obj.offset = self.offset
         obj.llen = self.llen
         obj.vlen = self.vlen
+        obj.expl_lenindef = self.expl_lenindef
+        obj.lenindef = self.lenindef
+        obj.ber_encoded = self.ber_encoded
         return obj
 
     def __iter__(self):
@@ -3193,11 +3247,17 @@ class ObjectIdentifier(Obj):
             )
         v, tail = v[:l], v[l:]
         arcs = []
+        ber_encoded = False
         while len(v) > 0:
             i = 0
             arc = 0
             while True:
                 octet = indexbytes(v, i)
+                if i == 0 and octet == 0x80:
+                    if ctx.get("bered", False):
+                        ber_encoded = True
+                    else:
+                        raise DecodeError("non normalized arc encoding")
                 arc = (arc << 7) | (octet & 0x7F)
                 if octet & 0x80 == 0:
                     arcs.append(arc)
@@ -3229,6 +3289,8 @@ class ObjectIdentifier(Obj):
             optional=self.optional,
             _decoded=(offset, llen, l),
         )
+        if ber_encoded:
+            obj.ber_encoded = True
         return obj, tail
 
     def __repr__(self):
@@ -3236,6 +3298,7 @@ class ObjectIdentifier(Obj):
 
     def pps(self, decode_path=()):
         yield _pp(
+            obj=self,
             asn1_type_name=self.asn1_type_name,
             obj_name=self.__class__.__name__,
             decode_path=decode_path,
@@ -3253,6 +3316,7 @@ class ObjectIdentifier(Obj):
             expl_llen=self.expl_llen if self.expled else None,
             expl_vlen=self.expl_vlen if self.expled else None,
             expl_lenindef=self.expl_lenindef,
+            ber_encoded=self.ber_encoded,
             bered=self.bered,
         )
         for pp in self.pps_lenindef(decode_path):
@@ -3296,7 +3360,10 @@ class Enumerated(Integer):
         if isinstance(value, self.__class__):
             value = value._value
         elif isinstance(value, integer_types):
-            if value not in list(self.specs.values()):
+            for _value in itervalues(self.specs):
+                if _value == value:
+                    break
+            else:
                 raise DecodeError(
                     "unknown integer value: %s" % value,
                     klass=self.__class__,
@@ -3321,6 +3388,9 @@ class Enumerated(Integer):
         obj.offset = self.offset
         obj.llen = self.llen
         obj.vlen = self.vlen
+        obj.expl_lenindef = self.expl_lenindef
+        obj.lenindef = self.lenindef
+        obj.ber_encoded = self.ber_encoded
         return obj
 
     def __call__(
@@ -3462,6 +3532,7 @@ class CommonString(OctetString):
         if self.ready:
             value = hexenc(bytes(self)) if no_unicode else self.__unicode__()
         yield _pp(
+            obj=self,
             asn1_type_name=self.asn1_type_name,
             obj_name=self.__class__.__name__,
             decode_path=decode_path,
@@ -3498,7 +3569,7 @@ class AllowableCharsMixin(object):
     def allowable_chars(self):
         if PY2:
             return self._allowable_chars
-        return set(six_unichr(c) for c in self._allowable_chars)
+        return frozenset(six_unichr(c) for c in self._allowable_chars)
 
 
 class NumericString(AllowableCharsMixin, CommonString):
@@ -3514,11 +3585,11 @@ class NumericString(AllowableCharsMixin, CommonString):
     tag_default = tag_encode(18)
     encoding = "ascii"
     asn1_type_name = "NumericString"
-    _allowable_chars = set(digits.encode("ascii") + b" ")
+    _allowable_chars = frozenset(digits.encode("ascii") + b" ")
 
     def _value_sanitize(self, value):
         value = super(NumericString, self)._value_sanitize(value)
-        if not set(value) <= self._allowable_chars:
+        if not frozenset(value) <= self._allowable_chars:
             raise DecodeError("non-numeric value")
         return value
 
@@ -3535,13 +3606,13 @@ class PrintableString(AllowableCharsMixin, CommonString):
     tag_default = tag_encode(19)
     encoding = "ascii"
     asn1_type_name = "PrintableString"
-    _allowable_chars = set(
+    _allowable_chars = frozenset(
         (ascii_letters + digits + " '()+,-./:=?").encode("ascii")
     )
 
     def _value_sanitize(self, value):
         value = super(PrintableString, self)._value_sanitize(value)
-        if not set(value) <= self._allowable_chars:
+        if not frozenset(value) <= self._allowable_chars:
             raise DecodeError("non-printable value")
         return value
 
@@ -3590,14 +3661,16 @@ class UTCTime(CommonString):
     datetime.datetime(2017, 9, 30, 22, 7, 50)
     >>> UTCTime(datetime(2057, 9, 30, 22, 7, 50)).todatetime()
     datetime.datetime(1957, 9, 30, 22, 7, 50)
+
+    .. warning::
+
+       No BER encodings are supported. Only DER.
     """
     __slots__ = ()
     tag_default = tag_encode(23)
     encoding = "ascii"
     asn1_type_name = "UTCTime"
 
-    fmt = "%y%m%d%H%M%SZ"
-
     def __init__(
             self,
             value=None,
@@ -3636,24 +3709,36 @@ class UTCTime(CommonString):
             if self._value is None:
                 self._value = default
 
+    def _strptime(self, value):
+        # datetime.strptime's format: %y%m%d%H%M%SZ
+        if len(value) != LEN_YYMMDDHHMMSSZ:
+            raise ValueError("invalid UTCTime length")
+        if value[-1] != "Z":
+            raise ValueError("non UTC timezone")
+        return datetime(
+            2000 + int(value[:2]),  # %y
+            int(value[2:4]),  # %m
+            int(value[4:6]),  # %d
+            int(value[6:8]),  # %H
+            int(value[8:10]),  # %M
+            int(value[10:12]),  # %S
+        )
+
     def _value_sanitize(self, value):
-        if isinstance(value, self.__class__):
-            return value._value
-        if isinstance(value, datetime):
-            return value.strftime(self.fmt).encode("ascii")
         if isinstance(value, binary_type):
             try:
                 value_decoded = value.decode("ascii")
             except (UnicodeEncodeError, UnicodeDecodeError) as err:
                 raise DecodeError("invalid UTCTime encoding")
-            if len(value_decoded) == LEN_YYMMDDHHMMSSZ:
-                try:
-                    datetime.strptime(value_decoded, self.fmt)
-                except (TypeError, ValueError):
-                    raise DecodeError("invalid UTCTime format")
-                return value
-            else:
-                raise DecodeError("invalid UTCTime length")
+            try:
+                self._strptime(value_decoded)
+            except (TypeError, ValueError) as err:
+                raise DecodeError("invalid UTCTime format: %r" % err)
+            return value
+        if isinstance(value, self.__class__):
+            return value._value
+        if isinstance(value, datetime):
+            return value.strftime("%y%m%d%H%M%SZ").encode("ascii")
         raise InvalidValueType((self.__class__, datetime))
 
     def __eq__(self, their):
@@ -3678,7 +3763,7 @@ class UTCTime(CommonString):
         having < 50 years are treated as 20xx, 19xx otherwise, according
         to X.509 recomendation.
         """
-        value = datetime.strptime(self._value.decode("ascii"), self.fmt)
+        value = self._strptime(self._value.decode("ascii"))
         year = value.year % 100
         return datetime(
             year=(2000 + year) if year < 50 else (1900 + year),
@@ -3694,6 +3779,7 @@ class UTCTime(CommonString):
 
     def pps(self, decode_path=()):
         yield _pp(
+            obj=self,
             asn1_type_name=self.asn1_type_name,
             obj_name=self.__class__.__name__,
             decode_path=decode_path,
@@ -3729,54 +3815,85 @@ class GeneralizedTime(UTCTime):
     '20170930220750.000123Z'
     >>> t = GeneralizedTime(datetime(2057, 9, 30, 22, 7, 50))
     GeneralizedTime GeneralizedTime 2057-09-30T22:07:50
+
+    .. warning::
+
+       No BER encodings are supported. Only DER.
+
+    .. warning::
+
+       Only microsecond fractions are supported.
+       :py:exc:`pyderasn.DecodeError` will be raised during decoding of
+       higher precision values.
     """
     __slots__ = ()
     tag_default = tag_encode(24)
     asn1_type_name = "GeneralizedTime"
 
-    fmt = "%Y%m%d%H%M%SZ"
-    fmt_ms = "%Y%m%d%H%M%S.%fZ"
+    def _strptime(self, value):
+        l = len(value)
+        if l == LEN_YYYYMMDDHHMMSSZ:
+            # datetime.strptime's format: %y%m%d%H%M%SZ
+            if value[-1] != "Z":
+                raise ValueError("non UTC timezone")
+            return datetime(
+                int(value[:4]),  # %Y
+                int(value[4:6]),  # %m
+                int(value[6:8]),  # %d
+                int(value[8:10]),  # %H
+                int(value[10:12]),  # %M
+                int(value[12:14]),  # %S
+            )
+        if l >= LEN_YYYYMMDDHHMMSSDMZ:
+            # datetime.strptime's format: %Y%m%d%H%M%S.%fZ
+            if value[-1] != "Z":
+                raise ValueError("non UTC timezone")
+            if value[14] != ".":
+                raise ValueError("no fractions separator")
+            us = value[15:-1]
+            if us[-1] == "0":
+                raise ValueError("trailing zero")
+            us_len = len(us)
+            if us_len > 6:
+                raise ValueError("only microsecond fractions are supported")
+            us = int(us + ("0" * (6 - us_len)))
+            decoded = datetime(
+                int(value[:4]),  # %Y
+                int(value[4:6]),  # %m
+                int(value[6:8]),  # %d
+                int(value[8:10]),  # %H
+                int(value[10:12]),  # %M
+                int(value[12:14]),  # %S
+                us,  # %f
+            )
+            return decoded
+        raise ValueError("invalid GeneralizedTime length")
 
     def _value_sanitize(self, value):
-        if isinstance(value, self.__class__):
-            return value._value
-        if isinstance(value, datetime):
-            return value.strftime(
-                self.fmt_ms if value.microsecond > 0 else self.fmt
-            ).encode("ascii")
         if isinstance(value, binary_type):
             try:
                 value_decoded = value.decode("ascii")
             except (UnicodeEncodeError, UnicodeDecodeError) as err:
                 raise DecodeError("invalid GeneralizedTime encoding")
-            if len(value_decoded) == LEN_YYYYMMDDHHMMSSZ:
-                try:
-                    datetime.strptime(value_decoded, self.fmt)
-                except (TypeError, ValueError):
-                    raise DecodeError(
-                        "invalid GeneralizedTime (without ms) format",
-                    )
-                return value
-            elif len(value_decoded) >= LEN_YYYYMMDDHHMMSSDMZ:
-                try:
-                    datetime.strptime(value_decoded, self.fmt_ms)
-                except (TypeError, ValueError):
-                    raise DecodeError(
-                        "invalid GeneralizedTime (with ms) format",
-                    )
-                return value
-            else:
+            try:
+                self._strptime(value_decoded)
+            except (TypeError, ValueError) as err:
                 raise DecodeError(
-                    "invalid GeneralizedTime length",
+                    "invalid GeneralizedTime format: %r" % err,
                     klass=self.__class__,
                 )
+            return value
+        if isinstance(value, self.__class__):
+            return value._value
+        if isinstance(value, datetime):
+            encoded = value.strftime("%Y%m%d%H%M%S")
+            if value.microsecond > 0:
+                encoded = encoded + (".%06d" % value.microsecond).rstrip("0")
+            return (encoded + "Z").encode("ascii")
         raise InvalidValueType((self.__class__, datetime))
 
     def todatetime(self):
-        value = self._value.decode("ascii")
-        if len(value) == LEN_YYYYMMDDHHMMSSZ:
-            return datetime.strptime(value, self.fmt)
-        return datetime.strptime(value, self.fmt_ms)
+        return self._strptime(self._value.decode("ascii"))
 
 
 class GraphicString(CommonString):
@@ -3895,8 +4012,6 @@ class Choice(Obj):
                 self._value = default_obj.copy()._value
 
     def _value_sanitize(self, value):
-        if isinstance(value, self.__class__):
-            return value._value
         if isinstance(value, tuple) and len(value) == 2:
             choice, obj = value
             spec = self.specs.get(choice)
@@ -3905,6 +4020,8 @@ class Choice(Obj):
             if not isinstance(obj, spec.__class__):
                 raise InvalidValueType((spec,))
             return (choice, spec(obj))
+        if isinstance(value, self.__class__):
+            return value._value
         raise InvalidValueType((self.__class__, tuple))
 
     @property
@@ -3926,6 +4043,9 @@ class Choice(Obj):
         obj.offset = self.offset
         obj.llen = self.llen
         obj.vlen = self.vlen
+        obj.expl_lenindef = self.expl_lenindef
+        obj.lenindef = self.lenindef
+        obj.ber_encoded = self.ber_encoded
         value = self._value
         if value is not None:
             obj._value = (value[0], value[1].copy())
@@ -3997,7 +4117,7 @@ class Choice(Obj):
         return self._value[1].encode()
 
     def _decode(self, tlv, offset, decode_path, ctx, tag_only):
-        for choice, spec in self.specs.items():
+        for choice, spec in iteritems(self.specs):
             sub_decode_path = decode_path + (choice,)
             try:
                 spec.decode(
@@ -4007,6 +4127,7 @@ class Choice(Obj):
                     decode_path=sub_decode_path,
                     ctx=ctx,
                     tag_only=True,
+                    _ctx_immutable=False,
                 )
             except TagMismatch:
                 continue
@@ -4025,6 +4146,7 @@ class Choice(Obj):
             leavemm=True,
             decode_path=sub_decode_path,
             ctx=ctx,
+            _ctx_immutable=False,
         )
         obj = self.__class__(
             schema=self.specs,
@@ -4044,6 +4166,7 @@ class Choice(Obj):
 
     def pps(self, decode_path=()):
         yield _pp(
+            obj=self,
             asn1_type_name=self.asn1_type_name,
             obj_name=self.__class__.__name__,
             decode_path=decode_path,
@@ -4134,12 +4257,12 @@ class Any(Obj):
         self.defined = None
 
     def _value_sanitize(self, value):
+        if isinstance(value, binary_type):
+            return value
         if isinstance(value, self.__class__):
             return value._value
         if isinstance(value, Obj):
             return value.encode()
-        if isinstance(value, binary_type):
-            return value
         raise InvalidValueType((self.__class__, Obj, binary_type))
 
     @property
@@ -4163,6 +4286,9 @@ class Any(Obj):
         obj.offset = self.offset
         obj.llen = self.llen
         obj.vlen = self.vlen
+        obj.expl_lenindef = self.expl_lenindef
+        obj.lenindef = self.lenindef
+        obj.ber_encoded = self.ber_encoded
         return obj
 
     def __eq__(self, their):
@@ -4226,6 +4352,7 @@ class Any(Obj):
                     decode_path=decode_path + (str(chunk_i),),
                     leavemm=True,
                     ctx=ctx,
+                    _ctx_immutable=False,
                 )
                 vlen += chunk.tlvlen
                 sub_offset += chunk.tlvlen
@@ -4270,6 +4397,7 @@ class Any(Obj):
 
     def pps(self, decode_path=()):
         yield _pp(
+            obj=self,
             asn1_type_name=self.asn1_type_name,
             obj_name=self.__class__.__name__,
             decode_path=decode_path,
@@ -4319,8 +4447,7 @@ def get_def_by_path(defines_by_path, sub_decode_path):
 def abs_decode_path(decode_path, rel_path):
     """Create an absolute decode path from current and relative ones
 
-    :param decode_path: current decode path, starting point.
-                        Tuple of strings
+    :param decode_path: current decode path, starting point. Tuple of strings
     :param rel_path: relative path to ``decode_path``. Tuple of strings.
                      If first tuple's element is "/", then treat it as
                      an absolute path, ignoring ``decode_path`` as
@@ -4475,7 +4602,7 @@ class Sequence(Obj):
 
     @property
     def ready(self):
-        for name, spec in self.specs.items():
+        for name, spec in iteritems(self.specs):
             value = self._value.get(name)
             if value is None:
                 if spec.optional:
@@ -4490,7 +4617,7 @@ class Sequence(Obj):
     def bered(self):
         if self.expl_lenindef or self.lenindef or self.ber_encoded:
             return True
-        return any(value.bered for value in self._value.values())
+        return any(value.bered for value in itervalues(self._value))
 
     def copy(self):
         obj = self.__class__(schema=self.specs)
@@ -4501,7 +4628,10 @@ class Sequence(Obj):
         obj.offset = self.offset
         obj.llen = self.llen
         obj.vlen = self.vlen
-        obj._value = {k: v.copy() for k, v in self._value.items()}
+        obj.expl_lenindef = self.expl_lenindef
+        obj.lenindef = self.lenindef
+        obj.ber_encoded = self.ber_encoded
+        obj._value = {k: v.copy() for k, v in iteritems(self._value)}
         return obj
 
     def __eq__(self, their):
@@ -4562,7 +4692,7 @@ class Sequence(Obj):
 
     def _encoded_values(self):
         raws = []
-        for name, spec in self.specs.items():
+        for name, spec in iteritems(self.specs):
             value = self._value.get(name)
             if value is None:
                 if spec.optional:
@@ -4628,7 +4758,7 @@ class Sequence(Obj):
         values = {}
         ber_encoded = False
         ctx_allow_default_values = ctx.get("allow_default_values", False)
-        for name, spec in self.specs.items():
+        for name, spec in iteritems(self.specs):
             if spec.optional and (
                     (lenindef and v[:EOC_LEN].tobytes() == EOC) or
                     len(v) == 0
@@ -4642,6 +4772,7 @@ class Sequence(Obj):
                     leavemm=True,
                     decode_path=sub_decode_path,
                     ctx=ctx,
+                    _ctx_immutable=False,
                 )
             except TagMismatch:
                 if spec.optional:
@@ -4666,6 +4797,7 @@ class Sequence(Obj):
                             leavemm=True,
                             decode_path=sub_sub_decode_path,
                             ctx=ctx,
+                            _ctx_immutable=False,
                         )
                         if len(defined_tail) > 0:
                             raise DecodeError(
@@ -4685,6 +4817,7 @@ class Sequence(Obj):
                         leavemm=True,
                         decode_path=sub_decode_path + (DecodePathDefBy(defined_by),),
                         ctx=ctx,
+                        _ctx_immutable=False,
                     )
                     if len(defined_tail) > 0:
                         raise DecodeError(
@@ -4766,6 +4899,7 @@ class Sequence(Obj):
 
     def pps(self, decode_path=()):
         yield _pp(
+            obj=self,
             asn1_type_name=self.asn1_type_name,
             obj_name=self.__class__.__name__,
             decode_path=decode_path,
@@ -4818,6 +4952,9 @@ class Set(Sequence):
         v = b"".join(raws)
         return b"".join((self.tag, len_encode(len(v)), v))
 
+    def _specs_items(self):
+        return iteritems(self.specs)
+
     def _decode(self, tlv, offset, decode_path, ctx, tag_only):
         try:
             t, tlen, lv = tag_strip(tlv)
@@ -4872,11 +5009,11 @@ class Set(Sequence):
         ctx_allow_default_values = ctx.get("allow_default_values", False)
         ctx_allow_unordered_set = ctx.get("allow_unordered_set", False)
         value_prev = memoryview(v[:0])
-        specs_items = self.specs.items
+
         while len(v) > 0:
             if lenindef and v[:EOC_LEN].tobytes() == EOC:
                 break
-            for name, spec in specs_items():
+            for name, spec in self._specs_items():
                 sub_decode_path = decode_path + (name,)
                 try:
                     spec.decode(
@@ -4886,6 +5023,7 @@ class Set(Sequence):
                         decode_path=sub_decode_path,
                         ctx=ctx,
                         tag_only=True,
+                        _ctx_immutable=False,
                     )
                 except TagMismatch:
                     continue
@@ -4902,6 +5040,7 @@ class Set(Sequence):
                 leavemm=True,
                 decode_path=sub_decode_path,
                 ctx=ctx,
+                _ctx_immutable=False,
             )
             value_len = value.fulllen
             if value_prev.tobytes() > v[:value_len].tobytes():
@@ -5072,6 +5211,9 @@ class SequenceOf(Obj):
         obj.offset = self.offset
         obj.llen = self.llen
         obj.vlen = self.vlen
+        obj.expl_lenindef = self.expl_lenindef
+        obj.lenindef = self.lenindef
+        obj.ber_encoded = self.ber_encoded
         obj._value = [v.copy() for v in self._value]
         return obj
 
@@ -5211,6 +5353,7 @@ class SequenceOf(Obj):
                 leavemm=True,
                 decode_path=sub_decode_path,
                 ctx=ctx,
+                _ctx_immutable=False,
             )
             value_len = value.fulllen
             if ordering_check:
@@ -5268,6 +5411,7 @@ class SequenceOf(Obj):
 
     def pps(self, decode_path=()):
         yield _pp(
+            obj=self,
             asn1_type_name=self.asn1_type_name,
             obj_name=self.__class__.__name__,
             decode_path=decode_path,
@@ -5343,7 +5487,7 @@ def generic_decoder():  # pragma: no cover
     choice = PrimitiveTypes()
     choice.specs["SequenceOf"] = SequenceOf(schema=choice)
     choice.specs["SetOf"] = SetOf(schema=choice)
-    for i in range(31):
+    for i in six_xrange(31):
         choice.specs["SequenceOf%d" % i] = SequenceOf(
             schema=choice,
             expl=tag_ctxc(i),