Add server name verification in instance search

There are Nova API calls that can accept a server name
as a regex parameter. For example, if the command
'nova list --name <some_pattern>' is invoked with
an incorrect value of the pattern, the nova-api makes
a request to database and returns Http 500 error. Seems
it's not convenient.

This fix checks the pattern. If it isn't correct,
the nova-api returns error 400 with a prompt of a bad regex.

Change-Id: Iad63c668d09ec6a82ace29700fb4949c1acfbe1c
Closes-Bug: #1603728

nova/api/openstack/compute/servers.py

@@ -14,6 +14,8 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
+import re
+
 from oslo_log import log as logging
 import oslo_messaging as messaging
 from oslo_utils import strutils
@@ -260,6 +262,14 @@ class ServersController(wsgi.Controller):
                 msg = _("Only administrators may list deleted instances")
                 raise exc.HTTPForbidden(explanation=msg)
 
+        # Verify the value of the 'name' option is a correct regex.
+        if 'name' in search_opts:
+            try:
+                re.compile(search_opts['name'])
+            except re.error:
+                msg = _("The regex for server name is incorrect")
+                raise exc.HTTPBadRequest(explanation=msg)
+
         if api_version_request.is_supported(req, min_version='2.26'):
             for tag_filter in TAG_SEARCH_FILTERS:
                 if tag_filter in search_opts:

nova/tests/unit/api/openstack/compute/test_serversV21.py

@@ -585,6 +585,11 @@ class ServersControllerTest(ControllerTest):
         num_servers = len(res_dict['servers'])
         self.assertEqual(0, num_servers)
 
+    def test_get_server_details_with_bad_name(self):
+        req = self.req('/fake/servers/detail?name=%2Binstance')
+        self.assertRaises(webob.exc.HTTPBadRequest,
+                          self.controller.index, req)
+
     def test_get_server_details_with_limit(self):
         req = self.req('/fake/servers/detail?limit=3')
         res = self.controller.detail(req)