Add entity body validation helper

Add a _valid_body() helper for the servers API to avoid repeating the
same tests in multiple methods. Include a check that the 'server' value
is actually a dict.

Also remove the superfluous checking of req.body which is a leftover
from when the body wasn't a method parameter.

Change-Id: If8114cc76d68567005c85c803f29e30e034db89a

2 files changed, 19 insertions, 11 deletions

diff --git a/nova/api/openstack/compute/servers.py b/nova/api/openstack/compute/servers.py
index fc4905a11..4c4b86aa8 100644
--- a/nova/api/openstack/compute/servers.py
+++ b/nova/api/openstack/compute/servers.py
@@ -613,10 +613,7 @@ class Controller(wsgi.Controller):
     @wsgi.deserializers(xml=CreateDeserializer)
     def create(self, req, body):
         """Creates a new server for a given user."""
-        if not body:
-            raise exc.HTTPUnprocessableEntity()
-
-        if not 'server' in body:
+        if not self.is_valid_body(body, 'server'):
             raise exc.HTTPUnprocessableEntity()
 
         body['server']['key_name'] = self._get_key_name(req, body)
@@ -815,13 +812,7 @@ class Controller(wsgi.Controller):
     @wsgi.serializers(xml=ServerTemplate)
     def update(self, req, id, body):
         """Update server then pass on to version-specific controller."""
-        if len(req.body) == 0:
-            raise exc.HTTPUnprocessableEntity()
-
-        if not body:
-            raise exc.HTTPUnprocessableEntity()
-
-        if not 'server' in body:
+        if not self.is_valid_body(body, 'server'):
             raise exc.HTTPUnprocessableEntity()
 
         ctxt = req.environ['nova.context']
diff --git a/nova/api/openstack/wsgi.py b/nova/api/openstack/wsgi.py
index 658b59645..a9fa3847a 100644
--- a/nova/api/openstack/wsgi.py
+++ b/nova/api/openstack/wsgi.py
@@ -1102,6 +1102,23 @@ class Controller(object):
         else:
             self._view_builder = None
 
+    @staticmethod
+    def is_valid_body(body, entity_name):
+        if not (body and entity_name in body):
+            return False
+
+        def is_dict(d):
+            try:
+                d.get(None)
+                return True
+            except AttributeError:
+                return False
+
+        if not is_dict(body[entity_name]):
+            return False
+
+        return True
+
 
 class Fault(webob.exc.HTTPException):
     """Wrap webob.exc.HTTPException to provide API friendly response."""