Fix TypeError conversion in API layer

Fix conversion of TypeError to Fault in ResourceExceptionHandler.
TypeError can result when the list of extensions is inovked if the
parameters don't match the extension method's signature.

Specifically, if an empty body was sent with an HTTP POST to create a
server, a 500 error was returned.  This change is a fix to properly
return a 400 instead.

(In Python2.6, the ex_value argument of __exit__ is type string when
ex_type is a TypeError, which caused the conversion logic to get
skipped.)

bug 1035120

Change-Id: I96ad335a6338523345d28b7e744dbc7449b4753d

2 files changed, 17 insertions, 1 deletions

diff --git a/nova/api/openstack/wsgi.py b/nova/api/openstack/wsgi.py
index 3ea7c1c7c..9f8bf6367 100644
--- a/nova/api/openstack/wsgi.py
+++ b/nova/api/openstack/wsgi.py
@@ -628,7 +628,11 @@ class ResourceExceptionHandler(object):
         elif isinstance(ex_value, exception.Invalid):
             raise Fault(exception.ConvertedException(
                 code=ex_value.code, explanation=unicode(ex_value)))
-        elif isinstance(ex_value, TypeError):
+
+        # Under python 2.6, TypeError's exception value is actually a string,
+        # so test # here via ex_type instead:
+        # http://bugs.python.org/issue7853
+        elif issubclass(ex_type, TypeError):
             exc_info = (ex_type, ex_value, ex_traceback)
             LOG.error(_('Exception handling resource: %s') % ex_value,
                     exc_info=exc_info)
diff --git a/nova/tests/api/openstack/test_wsgi.py b/nova/tests/api/openstack/test_wsgi.py
index f45450495..7427eb2af 100644
--- a/nova/tests/api/openstack/test_wsgi.py
+++ b/nova/tests/api/openstack/test_wsgi.py
@@ -752,6 +752,18 @@ class ResourceTest(test.TestCase):
         self.assertEqual(called, [2])
         self.assertEqual(response, 'foo')
 
+    def test_resource_exception_handler_type_error(self):
+        """A TypeError should be translated to a Fault/HTTP 400"""
+        def foo(a,):
+            return a
+
+        try:
+            with wsgi.ResourceExceptionHandler():
+                foo()  # generate a TypeError
+            self.fail("Should have raised a Fault (HTTP 400)")
+        except wsgi.Fault as fault:
+            self.assertEqual(400, fault.status_int)
+
 
 class ResponseObjectTest(test.TestCase):
     def test_default_code(self):