feat(transport): define acceptable integer range

The JSON parser in use (simplejson) supports Python big integers,
while none of the storage drivers can serialize them.  The acceptable
range to both bson and msgpack is -2^63 ~ 2^63-1.

Change-Id: I861201ea5493bbe4e1c0197000edbd8594162047
Fixes: bug #1202846

marconi/tests/transport/wsgi/test_messages.py

@@ -119,6 +119,15 @@ class MessagesBaseTest(base.TestBase):
 
             self.assertEquals(self.srmock.status, falcon.HTTP_400)
 
+    def test_unsupported_json(self):
+        for document in ('{"overflow": 9223372036854775808}',
+                         '{"underflow": -9223372036854775809}'):
+            self.simulate_post(self.queue_path + '/messages',
+                               body=document,
+                               headers=self.headers)
+
+            self.assertEquals(self.srmock.status, falcon.HTTP_400)
+
     def test_delete(self):
         path = self.queue_path + '/messages'
         self._post_messages(path)

marconi/transport/helpers.py

@@ -21,6 +21,20 @@ class MalformedJSON(ValueError):
     pass
 
 
+class OverflowedJSONInteger(OverflowError):
+    """JSON integer is too large."""
+    pass
+
+
+def _json_int(s):
+    """Parse a string as a base 10 64-bit signed integer."""
+    i = int(s)
+    if not (int(-2 ** 63) <= i <= int(2 ** 63 - 1)):
+        raise OverflowedJSONInteger()
+
+    return i
+
+
 def read_json(stream, len):
     """Like json.load, but converts ValueError to MalformedJSON upon failure.
 
@@ -28,7 +42,7 @@ def read_json(stream, len):
     :param len: the number of bytes to read from stream
     """
     try:
-        return json.loads(stream.read(len))
+        return json.loads(stream.read(len), parse_int=_json_int)
 
     except ValueError as ex:
         raise MalformedJSON(ex)

marconi/transport/wsgi/helpers.py

@@ -62,6 +62,11 @@ def filter_stream(stream, len, spec, doctype=JSONObject):
         description = _('Body could not be parsed.')
         raise exceptions.HTTPBadRequestBody(description)
 
+    except helpers.OverflowedJSONInteger as ex:
+        LOG.exception(ex)
+        description = _('JSON contains integer that is too large.')
+        raise exceptions.HTTPBadRequestBody(description)
+
     except Exception as ex:
         # Error while reading from the network/server
         LOG.exception(ex)