Fix faulty 404 errors when requesting bad versions

The problem came down to the `_dispatch` method of the openstack
common wsgi router object. When a match was not found it returned
a webob 404 exception directly rather than allowing it to be
wrapped in a serializer.

The fix involved extending the `Router` object and reimplementing
the `_dispatch()` method to use the `Fault` object that serializes
exceptions.

Change-Id: I24a590f65ff655b25cfd7d84786df3055af701f1
Fixes: bug #1174960

reddwarf/common/wsgi.py

@@ -43,7 +43,6 @@ from reddwarf.openstack.common import log as logging
 from reddwarf.common import cfg
 
 CONTEXT_KEY = 'reddwarf.context'
-Router = openstack_wsgi.Router
 Debug = openstack_wsgi.Debug
 Middleware = openstack_wsgi.Middleware
 JSONDictSerializer = openstack_wsgi.JSONDictSerializer
@@ -207,6 +206,26 @@ class VersionedURLMap(object):
         return app(environ, start_response)
 
 
+class Router(openstack_wsgi.Router):
+
+    # Original router did not allow for serialization of the 404 error.
+    # To fix this the _dispatch was modified to use Fault() objects.
+    @staticmethod
+    @webob.dec.wsgify
+    def _dispatch(req):
+        """
+        Called by self._router after matching the incoming request to a route
+        and putting the information into req.environ.  Either returns 404
+        or the routed WSGI app's response.
+        """
+
+        match = req.environ['wsgiorg.routing_args'][1]
+        if not match:
+            return Fault(webob.exc.HTTPNotFound())
+        app = match['controller']
+        return app
+
+
 class Request(openstack_wsgi.Request):
 
     @property

reddwarf/tests/unittests/router/__init__.py

@@ -0,0 +1,13 @@
+#    Copyright 2013 OpenStack Foundation
+#
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.

reddwarf/tests/unittests/router/test_router.py

@@ -0,0 +1,52 @@
+#    Copyright 2013 OpenStack Foundation
+#
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+
+import testtools
+
+from reddwarf.common.wsgi import Router, Fault
+
+from routes import Mapper
+
+
+class FakeRequst(object):
+    """A fake webob request object designed to cause 404.
+
+    The dispatcher actually checks if the given request is a dict and throws
+    an error if it is. This object wrapper tricks the dispatcher into
+    handling the request like a regular request.
+    """
+
+    environ = {
+        "wsgiorg.routing_args": [
+            False,
+            False
+        ]
+    }
+
+
+class TestRouter(testtools.TestCase):
+    """Test case for trove `Router` extensions."""
+
+    def setUp(self):
+        super(TestRouter, self).setUp()
+        self.mapper = Mapper()
+
+    def test_404_is_fault(self):
+        """Test that the dispatcher wraps 404's in a `Fault`."""
+
+        fake_request = FakeRequst()
+
+        response = Router._dispatch(fake_request)
+
+        assert isinstance(response, Fault)