LDAP auxprop plugin for SASL-enabled servers.
Copyright (C) 2002 by Howard Chu, hyc@symas.com

This software is an experimental proof-of-concept and is not intended for
general use. It is licensed under the terms ofthe OpenLDAP license.

The file ldapdb.c was written for Cyrus SASL 2.1.3 and OpenLDAP 2.1.3.
It can be compiled by copying into the Cyrus SASL source tree, in the
plugins subdirectory. No configuration or build script is provided.

To compile, type "make ldapdb.lo". To link, you'll have to copy the
link rule for one of the other plugins. Below is a sample on my Linux
system:

	/bin/sh ./libtool --mode=link gcc  -Wall -W -g -O2 -L/usr/local/lib -Wl,-rpath,/usr/local/lib -module -export-dynamic -rpath /usr/lib/sasl2 -o libldapdb.la  -version-info 2:4:0 ldapdb.lo -lldap -llber -lssl -lcrypto

Once installed, you need to add some config items to the SASL server's
config file in /usr/lib/sasl2. For example:

ldapdb_uri: ldapi://
ldapdb_id: root
ldapdb_pw: secret
ldapdb_mech: PLAIN

This config assumes an LDAP server on the same machine as the server
that is using SASL. The LDAP server must be configured to map the SASL
authcId "root" into a DN that has proxy authorization privileges to
every account that is allowed to login to this server. (See the OpenLDAP
Admin Guide for details.)

Unlike other LDAP-enabled plugins for other services that are common
on the web, this plugin does not require you to configure DN search
patterns to map usernames to LDAP DNs. This plugin requires SASL name
mapping to be configured on the target slapd. This approach keeps the
LDAP-specific configuration details in one place, the slapd.conf, and
makes the configuration of remote services much simpler.

One additional keyword "ldapdb_rc" may be specified in the config file.
The filename specified here will be put into the server's LDAPRC
environment variable, and libldap-specific config options may be set
in that ldaprc file. The main purpose behind this option is to allow
a client TLS certificate to be configured, so that SASL/EXTERNAL may
be used between the SASL server and the LDAP server. This is the most
optimal way to use this plugin when the servers are on separate machines.

This plugin likely has very poor performance. You'll need something
better for a real production environment. Please send feedback via the
openldap-software mailing list for now.

  -- Howard Chu, 2002-07-12

Update... With OpenLDAP 2.1.13 you can use SASL/EXTERNAL on ldapi://.
This is fast and secure, and needs no username or password to be stored.
The SASL config file is just

ldapdb_uri: ldapi://
ldapdb_mech: EXTERNAL

The slapd.conf will need to map these usernames to LDAP DNs:

sasl-regexp uidNumber=(.*)\\+gidNumber=(.*),cn=peercred,cn=external,cn=auth
	ldap:///dc=example,dc=com??sub?(&(uidNumber=$1)(gidNumber=$2))

sasl-regexp uid=(.*),cn=external,cn=auth
	ldap:///dc=example,dc=com??sub?(uid=$1)

