Strict SET values ordering check

[pyderasn.git] / pyderasn.py

diff --git a/pyderasn.py b/pyderasn.py
index a7732964dedcc8befbd31da6f4778cfb1cb23dc6..3dd3ea9c151a3f1ca6f571a7765614e1c5bf5b91 100755 (executable)
--- a/pyderasn.py
+++ b/pyderasn.py
@@ -215,6 +215,7 @@ Currently available context options:
 
 * :ref:`allow_default_values <allow_default_values_ctx>`
 * :ref:`allow_expl_oob <allow_expl_oob_ctx>`
+* :ref:`allow_unordered_set <allow_unordered_set_ctx>`
 * :ref:`bered <bered_ctx>`
 * :ref:`defines_by_path <defines_by_path_ctx>`
 
@@ -4708,6 +4709,14 @@ class Set(Sequence):
     """``SET`` structure type
 
     Its usage is identical to :py:class:`pyderasn.Sequence`.
+
+    .. _allow_unordered_set_ctx:
+
+    DER prohibits unordered values encoding and will raise an error
+    during decode. If If :ref:`bered <bered_ctx>` context option is set,
+    then no error will occure. Also you can disable strict values
+    ordering check by setting ``"allow_unordered_set": True``
+    :ref:`context <ctx>` option.
     """
     __slots__ = ()
     tag_default = tag_encode(form=TagFormConstructed, num=17)
@@ -4771,6 +4780,8 @@ class Set(Sequence):
         values = {}
         bered = False
         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:
@@ -4803,9 +4814,16 @@ class Set(Sequence):
                 ctx=ctx,
             )
             value_len = value.fulllen
-            sub_offset += value_len
-            vlen += value_len
-            v = v_tail
+            if value_prev.tobytes() > v[:value_len].tobytes():
+                if ctx_bered or ctx_allow_unordered_set:
+                    bered = True
+                else:
+                    raise DecodeError(
+                        "unordered " + self.asn1_type_name,
+                        klass=self.__class__,
+                        decode_path=sub_decode_path,
+                        offset=sub_offset,
+                    )
             if spec.default is None or value != spec.default:
                 pass
             elif ctx_bered or ctx_allow_default_values:
@@ -4818,6 +4836,10 @@ class Set(Sequence):
                     offset=sub_offset,
                 )
             values[name] = value
+            value_prev = v[:value_len]
+            sub_offset += value_len
+            vlen += value_len
+            v = v_tail
         obj = self.__class__(
             schema=self.specs,
             impl=self.tag,
@@ -4826,8 +4848,6 @@ class Set(Sequence):
             optional=self.optional,
             _decoded=(offset, llen, vlen + (EOC_LEN if lenindef else 0)),
         )
-        obj._value = values
-        obj.bered = bered
         if lenindef:
             if v[:EOC_LEN].tobytes() != EOC:
                 raise DecodeError(
@@ -4838,6 +4858,7 @@ class Set(Sequence):
                 )
             tail = v[EOC_LEN:]
             obj.lenindef = True
+        obj._value = values
         if not obj.ready:
             raise DecodeError(
                 "not all values are ready",
@@ -4845,6 +4866,7 @@ class Set(Sequence):
                 decode_path=decode_path,
                 offset=offset,
             )
+        obj.bered = bered
         return obj, tail