kamailio/modules/db2_ldap

db2_ldap module

Jan Janak

Iptel.org

Copyright � 2008 Iptel.org GmBH
_________________________________________________________________

Table of Contents

1. Admin Guide

1. Overview
2. Dependencies
3. Parameters

3.1. config (string)
3.2. reconnect_attempt (integer)

4. Functions

List of Examples

1.1. URI example
1.2. Example config
1.3. Configuration file example
1.4. Example reconnect_attempt

Chapter 1. Admin Guide

Table of Contents

1. Overview
2. Dependencies
3. Parameters

3.1. config (string)
3.2. reconnect_attempt (integer)

4. Functions

1. Overview

The LDAP module is database driver, i.e. it implements DBv2 API
functions. The goal is map database query defined by table, matching
fields and result fields to LDAP search in sub-tree defined by root,
object class, attributes and pass it to the OpenLDAP which
communicates with the LDAP server.

This procedure is sometimes tricky because the LDAP does not support
all database features or supports them in different manner. Here we
must express especially filtering and multi-values. The multi-value is
de facto array of single values. If the LDAP module get a multi-value
field then generates record for every single value, respectively for
every combination in case the more fields contain multi-value.

The LDAP supports natively "AND", "OR", "NOT" logical operators and
"equal", "non-equal", "less-or-equal" and "greater-or-equal"
comparison operators. Therefore "less" and "greater" operators are
mapped as "less/greater-or-equal-AND-not-equal". It's important
realize it when the attribute which will be used for filtering may
contain multi-value. The LDAP server evaluates comparison operator on
multi-value so that the result for record is true if the condition is
satisfied for any single value. The single values not satisfying
condition are not truncated. It implies two cases for positive
comparison, e.g. "equal", the result contains values not satisfying
the condition, the case may be handled by additional filter in the
LDAP module, the negative comparison, e.g. "non-equal", does not
return record at all. Because the LDAP module cannot know if the LDAP
attribute may logically contain multi-value so there is introduced DB
API option client_side_filtering which forces filtering such fields in
the LDAP module, i.e. the LDAP server returns larger result set
because the filtering condition is not passed there.

The syntax of client_side_filtering value is comma delimited of field
names which won't be used for server-side filter if such a field
appears in a match condition. Instead records will be filtered out in
module. It implies such fields MUST exist in result field list.

The necessary condition of successful filtering of particular
attribute at the LDAP server is correct attribute definition. The
"equal"/"non-equal" operator requires equality matching rule, the
"greater"/"less" operator requires ordering matching rule. If required
matching rule is missing the LDAP server silently returns empty result
set. In case of double filtering both at the LDAP servar and the LDAP
module, e.g. multi-value and equal comparison, check the LDAP server
matching rule satisfies your needs or use client_side_filtering
feature.

The LDAP server may be identified either complete specification of
host, user, password in URI or is specification reference to
connection section of config file. Note in the second case there is
only one slash.

Example 1.1. URI example
...
modparam("auth", "db_url", "ldap://admin:[email protected]");

modparam("auth", "db_url", "ldap:/ldap_server1");

...

Features:
* simple, SASL authentication, TLS
* server and client side filtering
* read-only queries
* optional referral chasing by OpenLDAP
* optional reference chasing by OpenLDAP

2. Dependencies

none

3. Parameters

3.1. config (string)
3.2. reconnect_attempt (integer)

3.1. config (string)

Default value is ldap.cfg.

The filename (relatively to ser config file) of mapping database to
LDAP definition. It is the main configuration file for the LDAP module
in SER. The configuration file maps database table names used in SER
to LDAP directory sub-trees to be searched. In addition to that the
configuration file also allows to configure the LDAP search filter and
maps database field names to LDAP attribute names and vice versa.

Example 1.2. Example config
...
modparam("ldap", "config", "my-ldap.cfg");
...

Example 1.3. Configuration file example
# Supported Attribute Type Names:
# * GeneralizedTime
# * Integer
# * BitString
# * Boolean
# * String
# * Binary
# * Float
#

[connection:ldap_server1]
host=127.0.0.1
port=389
username=ser
password=heslo
# LDAP or LDAP SASL authentication mechanism.
# Allowed values: none (default), simple, digest-md5, external
authtype=simple

# tls encryption
tls=off

# Specifies the file that contains certificates for all of the Certificate
# Authorities the ldap module will recognize.
ca_list=/home/kg/work/openssl/demoCA/cacert.pem

# Specifies what checks to perform on server certificates in a TLS session
# allowed values are never/allow/try/demand
# see the TLS_REQCERT tls option part of ldap.conf(8) man page for more details
require_certificate=demand

#
# Table credentials contains SIP digest authentication credentials.
#
[table:credentials]

# In our LDAP directory we store SIP digest credentials under
# "Digest Credentials" organization unit so this is where searches for digest
# credentials should start.
base = "ou=Digest Credentials,dc=iptel,dc=org"

# We search the whole subtree.
scope = subtree

# For digest credentials we are only interested in objects with objectClass
# 'digestAuthCredentials', objects of all other types are ignored.
filter = "(objectClass=digestAuthCredentials)"

# Mapping of field names to LDAP attribute names and vice versa. Names are
# delimited using ':', the first name is database field name as used in SER
# modules, the second name (after :) is corresponding LDAP attribute name,
# optionally preceeded with LDAP attribute syntax name in parentheses.
field_map = password : (Binary) digestPassword
field_map = realm : digestRealm
field_map = auth_username : digestUsername
field_map = uid : serUID
field_map = flags : (BitString) serFlags

# retrieve at most sizelimit entries for a search
#sizelimit = 2147483647

# wait at most timelimit seconds for a search to complete
#timelimit = 120

# chase references automatically by OpenLDAP. Default is "never"
# chase_references = never | searching | finding | always

# chase referrals automatically by OpenLDAP. Default is "no"
# chase_referrals = yes | no

#
# Domain table stores information about virtual domains
#
[table:domain]

# Objects mapping domain IDs to domain names and vice versa are stored
# in the subtree with the following root:
base = "ou=Domains,dc=iptel,dc=org"

scope = subtree

# We are only interested in serDomain objects when looking up information
# about virtual domains.
filter = "(objectClass=serDomain)"

field_map = did : (String) serDID
field_map = domain : (String) serDomain
field_map = flags : (BitString) serFlags

#
# Table domain_attrs contains domain attributes, domain attributes store
# extra information about virtual domains.
#
[table:domain_attrs]
base = "ou=Domains, dc=iptel,dc=org"
scope = subtree

filter = "(objectClass=serDomainAttr)"

field_map = did : serDID
field_map = name : serAttrName
field_map = type : (Integer) serAttrType
field_map = value : serAttrValue
field_map = flags : (BitString) serFlags

3.2. reconnect_attempt (integer)

Default value is 3.

Number of reconnect attempts when connection to the LDAP server is
lost.

Example 1.4. Example reconnect_attempt
...
modparam("ldap", "reconnect_attempt", "5");
...

4. Functions

none