Validate extra_specs type

Currently volume type creation with extra_specs set to null or
a string fails with AttributeError. This is because the current
validation logic assumes that extra_specs is a dictionary. This
patch fixes it by checking whether extra_specs is a dictionary
and raises InvalidInput if it is not.

Change-Id: Icc3580b5b1d784fa9c7fe07ac1c539af1b292075
Closes-bug: #1599106

cinder/tests/unit/api/contrib/test_types_manage.py

@@ -344,7 +344,9 @@ class VolumeTypesManageApiTest(test.TestCase):
 
     @ddt.data({'a' * 256: 'a'},
               {'a': 'a' * 256},
-              {'': 'a'})
+              {'': 'a'},
+              'foo',
+              None)
     def test_create_type_with_invalid_extra_specs(self, value):
         body = {"volume_type": {"name": "vol_type_1",
                                 "os-volume-type-access:is_public": False,

cinder/utils.py

@@ -1063,6 +1063,10 @@ def validate_integer(value, name, min_value=None, max_value=None):
 
 def validate_extra_specs(specs):
     """Validating key and value of extra specs."""
+    if not isinstance(specs, dict):
+        msg = _('extra_specs must be a dictionary.')
+        raise exception.InvalidInput(reason=msg)
+
     for key, value in specs.items():
         if key is not None:
             check_string_length(key, 'Key "%s"' % key,