I have automated DLs that use LDAP filters for membership criteria.  These filters are stored as binary data in the extensionData attribute of the group object, so they are not easily accessible by users who want to know what filter is being applied to a DL they own.

It was easy enough to extract the LDAP filter from the attribute, convert it to a string value, and display it.  But users don’t generally know how to read LDAP filters, let alone represented as a long line of text.  So I started looking for utilities or scripts that would take an LDAP filter, parse it, and display it with nesting.  Uh, yeah, there aren’t any.  I was determined, and so countless hours later I have a function that do such a thing.

The difficult part was keeping track of the level of nesting/indentation at any point. Since a filter can be written in almost any order as long as the resulting equation equals what you want, I couldn’t use any kind of static detection. Just because an open parentheses is following by another one doesn’t mean that you are, say, three levels nested. So the important part of the script keeps track of the indentation level as the cursor position moves through the filter.

I replace ampersands in the filter with crosshatches while working with it because I was having weird results otherwise, most likely because the ampersand is an operator in both LDAP and VBScript. And because the output is to an IE window and the indentation uses non-breaking spaces instead of the traditional tab (which doesn’t exist in HTML), I substitute the HTML string for a non-breaking space with a unique string of letters so the ampersand in that doesn’t get in the way.

Because this is part of a bigger script, I pulled out just the portion that formats the LDAP filter and displays it in an IE window. You just need to provide the “raw” filter, whether directly in the script or some other method. Copy and paste the code below or download it here.