Forbid non-stripped endpoint urls

Endpoint urls should not start with a whitespace character.

Change-Id: Ia8f998a0ca0e6249acbe23b1f8f1f894fae8123a
Closes-Bug: 1506594

keystone/common/validation/parameter_types.py

@@ -54,7 +54,7 @@ url = {
     # NOTE(edmondsw): we could do more to validate per various RFCs, but
     # decision was made to err on the side of leniency. The following is based
     # on rfc1738 section 2.1
-    'pattern': '[a-zA-Z0-9+.-]+:.+'
+    'pattern': '^[a-zA-Z0-9+.-]+:.+'
 }
 
 email = {

keystone/tests/unit/test_validation.py

@@ -90,7 +90,7 @@ _VALID_URLS = ['https://example.com', 'http://EXAMPLE.com/v3',
 
 _INVALID_URLS = [False, 'this is not a URL', 1234, 'www.example.com',
                  'localhost', 'http//something.com',
-                 'https//something.com']
+                 'https//something.com', ' http://example.com']
 
 _VALID_FILTERS = [{'interface': 'admin'},
                   {'region': 'US-WEST',