handle filter failure

Author: Vladimir Kotal

opengrok-indexer/src/main/java/org/opengrok/indexer/authorization/AuthorizationException.java

@@ -31,7 +31,7 @@ public AuthorizationException(Throwable ex) {
         super(ex);
     }
 
-    AuthorizationException(String msg) {
+    public AuthorizationException(String msg) {
         super(msg);
     }
 

plugins/src/opengrok/auth/plugin/LdapUserPlugin.java

@@ -104,7 +104,6 @@ protected boolean sessionExists(HttpServletRequest req) {
     }
 
     protected String getFilter(User user) {
-        String filter = null;
         String commonName;
 
         Matcher matcher = usernameCnPattern.matcher(user.getUsername());
@@ -113,14 +112,11 @@ protected String getFilter(User user) {
             LOGGER.log(Level.FINEST, "extracted common name {0} from {1}",
                 new Object[]{commonName, user.getUsername()});
         } else {
-            LOGGER.log(Level.WARNING, "cannot get common name out of {0}",
-                    user.getUsername());
-            return filter;
+            throw new AuthorizationException(String.format("cannot get common name out of %s",
+                    user.getUsername()));
         }
 
-        filter = "(&(objectclass=" + this.objectClass + ")(" + commonName + "))";
-        
-        return filter;
+        return "(&(objectclass=" + this.objectClass + ")(" + commonName + "))";
     }
 
     @Override