Convenient decod() helper method

[pyderasn.git] / pyderasn.py

diff --git a/pyderasn.py b/pyderasn.py
index f563afef86964240e57971d85c91fa35d40de0c8..5f0c0343ccd0d4153d29e6328fde4a73882229ec 100755 (executable)
--- a/pyderasn.py
+++ b/pyderasn.py
@@ -634,6 +634,7 @@ Various
 .. autoclass:: pyderasn.DecodeError
    :members: __init__
 .. autoclass:: pyderasn.NotEnoughData
+.. autoclass:: pyderasn.ExceedingData
 .. autoclass:: pyderasn.LenIndefForm
 .. autoclass:: pyderasn.TagMismatch
 .. autoclass:: pyderasn.InvalidLength
@@ -677,7 +678,7 @@ except ImportError:  # pragma: no cover
     def colored(what, *args, **kwargs):
         return what
 
-__version__ = "5.5"
+__version__ = "5.6"
 
 __all__ = (
     "Any",
@@ -689,6 +690,7 @@ __all__ = (
     "DecodeError",
     "DecodePathDefBy",
     "Enumerated",
+    "ExceedingData",
     "GeneralizedTime",
     "GeneralString",
     "GraphicString",
@@ -799,6 +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
 
@@ -1264,6 +1278,26 @@ 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`
@@ -2437,7 +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:
@@ -2508,7 +2542,7 @@ class BitString(Obj):
         if t == self.tag:
             if tag_only:  # pragma: no cover
                 return None
-            return self._decode_chunk(lv, offset, decode_path, ctx)
+            return self._decode_chunk(lv, offset, decode_path)
         if t == self.tag_constructed:
             if not ctx.get("bered", False):
                 raise DecodeError(
@@ -2827,7 +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:
@@ -2884,7 +2918,7 @@ class OctetString(Obj):
         if t == self.tag:
             if tag_only:
                 return None
-            return self._decode_chunk(lv, offset, decode_path, ctx)
+            return self._decode_chunk(lv, offset, decode_path)
         if t == self.tag_constructed:
             if not ctx.get("bered", False):
                 raise DecodeError(
@@ -5752,7 +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