Convenient decod() helper method

[pyderasn.git] / pyderasn.py

diff --git a/pyderasn.py b/pyderasn.py
index 87bb05665a08659cc36e48a7db270cafde75b2b0..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`