Do not add a default content type when replying

WebOb includes a default content_type, and that's incorrect for status
code such as 304. This fixes that by generalizing the previous fix we
introduced for the CORS middleware.

Change-Id: I57c47ee5627b17a4e266b9ac4bc038dfccb35012

oslo_middleware/base.py

@@ -17,10 +17,22 @@
 
 from inspect import getargspec
 import webob.dec
+import webob.request
+import webob.response
 
 from oslo_config import cfg
 
 
+class NoContentTypeResponse(webob.response.Response):
+
+    default_content_type = None  # prevents webob assigning content type
+
+
+class NoContentTypeRequest(webob.request.Request):
+
+    ResponseClass = NoContentTypeResponse
+
+
 class ConfigurableMiddleware(object):
     """Base WSGI middleware wrapper.
 
@@ -106,7 +118,7 @@ class ConfigurableMiddleware(object):
         """Do whatever you'd like to the response."""
         return response
 
-    @webob.dec.wsgify
+    @webob.dec.wsgify(RequestClass=NoContentTypeRequest)
     def __call__(self, req):
         response = self.process_request(req)
         if response:

oslo_middleware/cors.py

@@ -20,7 +20,7 @@ from oslo_config import cfg
 from oslo_middleware import base
 import six
 import webob.exc
-import webob.response
+
 
 LOG = logging.getLogger(__name__)
 
@@ -98,11 +98,6 @@ class InvalidOriginError(Exception):
             'CORS request from origin \'%s\' not permitted.' % origin)
 
 
-class _NoContentTypeResponse(webob.response.Response):
-
-    default_content_type = None  # prevents webob assigning content type
-
-
 class CORS(base.ConfigurableMiddleware):
     """CORS Middleware.
 
@@ -325,7 +320,7 @@ class CORS(base.ConfigurableMiddleware):
         # underlying middleware's response content needs to be persisted.
         # Otherwise, create a new response.
         if 200 > response.status_code or response.status_code >= 300:
-            response = _NoContentTypeResponse(status=webob.exc.HTTPOk.code)
+            response = base.NoContentTypeResponse(status=webob.exc.HTTPOk.code)
 
         # Does the request have an origin header? (Section 6.2.1)
         if 'Origin' not in request.headers:

oslo_middleware/tests/test_base.py

@@ -58,6 +58,17 @@ class TestBase(BaseTestCase):
 
         self.assertTrue(self.application.called_without_request)
 
+    def test_no_content_type_added(self):
+        class TestMiddleware(Middleware):
+            @staticmethod
+            def process_request(req):
+                return "foobar"
+
+        m = TestMiddleware(None)
+        request = webob.Request({}, method='GET')
+        response = request.get_response(m)
+        self.assertNotIn('Content-Type', response.headers)
+
     def test_paste_deploy_legacy(self):
         app = LegacyMiddlewareTest.factory(
             {'global': True}, local=True)(application)