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Introduction

One-two, one-two... is this thing working?

This is Kevin Montuori's trivial-ldap, with a few modifications.

A few years back, I needed some mechanism for querying AD servers, as part of a custom content connector for the FAST ESP search engine. I found trivial-ldap, and was soon using it to good effect.

After having used trivial-ldap for a while, I made some modifications, and asked Kevin to review them, and integrate them if he felt that they added value. Unfortunately, Kevin is too busy to spend time on trivial-ldap, so he graciously let me publish whatever changes I had.

Changes

LDAP Filter Parser

The LDAP filter parser has been rewritten from scratch, using cl-yacc. This makes filter parsing somewhat faster, and should also make it easier to maintain. The downside is one more dependency.

Attribute Naming

The original code used symbols in the current package to name LDAP attributes. This has changed, and all attribute names are now interned in the keyword package. So, something like

(ldap:attr-value *entry* 'cname)

should now be

(ldap:attr-value *entry* :cname)

and so on. Note: this is probably only important when working with an LDAP entry, as that is the only place where we use symbol identity for matching.

Binary Attributes

There was a tacit assumption in the trivial-ldap code that all attributes are UTF-8 encoded strings, while in reality they can be 7-bit ASCII (USASCII), UTF-8 or even binary. There is now a mechanism in place for giving hints to trivial-ldap that certain attributes should be treated as binary values --- such attributes will be returned as lists of (unsigned-byte 8), instead of as unicode strings.

The interface to this mechanism is

(ldap:attribute-binary-p <attribute-name>) => <generalized-boolean>

and

(setf (ldap:attribute-binary-p <attribute-name>) <generalized-boolean>)

Note: Elias Mårtenson has supplied some handy restarts that can be used when it turns out that an attribute cannot be converted to UTF-8 (which, in turn, probably means that it should be treated as binary). See handle-as-binary and handle-as-binary-and-add-known in trivial-ldap.lisp .

List Equivalents

Search filters and values can be specified as lists instead of as strings. This has two advantages:

  • Binary values can be specified (lists of octet values will not be treated as UTF-8 sequences).

  • It is not necessary to build string representations of a filter just to have the filter parser deconstruct it back to the representation that should be natural for Lisp.

  • Values can be specified as octet lists, strings or symbols -- when a symbol is specified, the actual value used is whatever (symbol-name <symbol>) returns.

  • The function #'listify-filter can be used to turn a string filter into an equivalent list representation; this should be useful for experimenting with the list format.

Examples:

(ldap:search *ldap* '(and (= objectclass person) (= cname "rayw")))

(let ((name "rayw"))
    (ldap:search *ldap* `(and (= objectclass person) (= cname ,name))))

Paging Through Results

Support for the LDAP Control Extension "Simple Paged Results" (rfc2696) has been added. It is invoked by setting the :size-limit search parameter to 0 (zero), and setting :paging-size to a positive integer. Note that the server imposes its own restrictions here, so the actual number of results in a batch may be lower than specified.

Apart from setting these two required parameters, the operation of the paging mechanism is wholly transparent: batches are fetched automatically whenever the #'next-search-result method has exhausted all entries in the current batch (assuming that the appropriate parameters have been specified, and that there are actually more results to be fetched.)

Examples:

(and (ldap:search *ldap* '(& (substring samaccountname "ra*") (= objectclass person))
                  :attributes '("1.1") :size-limit 0 :paging-size 500)
     (loop for entry = (ldap:next-search-result *ldap*)
           while entry
           count entry))