Serendipity commenting with proxy

It seems that out-of-the-box Serendipity does not support X-Forwarded-For -header. It means that any proxy in between loses original client information.

Here is my suggested patch to fix the issue:

--- serendipity/include/functions_comments.inc.php.orig 2013-01-25 14:10:03.058973150 +0200
+++ serendipity/include/functions_comments.inc.php      2013-05-14 11:34:35.302389894 +0300
@@ -782,7 +782,13 @@

     $title         = serendipity_db_escape_string(isset($commentInfo['title']) ? $commentInfo['title'] : '');
     $comments      = $commentInfo['comment'];
-    $ip            = serendipity_db_escape_string(isset($commentInfo['ip']) ? $commentInfo['ip'] : $_SERVER['REMOTE_ADDR']);
+    $ip            = serendipity_db_escape_string(isset($commentInfo['ip']) ?
+                        $commentInfo['ip'] :
+                        (
+                            isset($_SERVER['HTTP_X_FORWARDED_FOR']) ?
+                            $_SERVER['HTTP_X_FORWARDED_FOR'] :
+                            $_SERVER['REMOTE_ADDR']
+                        ));
     $commentsFixed = serendipity_db_escape_string($commentInfo['comment']);
     $name          = serendipity_db_escape_string($commentInfo['name']);
     $url           = serendipity_db_escape_string($commentInfo['url']);

This works on 1.6.2 and 1.7.0.