The Lightweight Directory Access Protocol (LDAP) (RFC 3377) provides
access to X.500 directory services. These services may be stand-alone
or part of a distributed directory service. This client API supports
LDAP over TCP (RFC2251), LDAP over TLS/SSL, and LDAP over IPC (UNIX
domain sockets). This API supports SASL (RFC2829) and Start TLS
(RFC2830) as well as a number of protocol extensions. This API is
loosely based upon IETF/LDAPEXT C LDAP API draft specification, a (orphaned)
work in progress.
The OpenLDAP Software package includes a stand-alone server in
various LDAP clients, and an LDAP client library used to provide
programmatic access to the LDAP protocol. This man page gives an
overview of the LDAP library routines.
Both synchronous and asynchronous APIs are provided. Also included are
various routines to parse the results returned from these routines.
These routines are found in the -lldap library.
The basic interaction is as follows. A session handle is
and set the protocol version to 3 by calling
The underlying session is established first operation is
issued. This would generally be a Start TLS or Bind operation.
A Start TLS operation is performed by calling
A LDAP bind operation is performed by calling
or one of its friends. Subsequently, other operations are performed
by calling one of the synchronous or asynchronous routines (e.g.,
Results returned from these routines are interpreted by calling the
LDAP parsing routines such as
The LDAP association and underlying connection is terminated by calling
Errors can be interpreted by calling
This library supports version 3 of the Lightweight Directory Access
Protocol (LDAPv3) as defined in RFC 3377. It also supports a variant
of version 2 of LDAP as defined by U-Mich LDAP and, to some degree,
RFC 1777. Version 2 (all variants) should be viewed as obsolete.
Version 3 should be used instead.
For backwards compatibility reasons, the library defaults to version 2.
Hence, all new applications (and all actively maintained applications)
to select version 3. The library manual pages assume version 3
has been selected.
INPUT and OUTPUT PARAMETERS
All character string input/output is expected to be/is UTF-8
encoded Unicode (version 3.2).
Distinguished names (DN) (and relative distinguished names (RDN) to
be passed to the LDAP routines should conform to RFC 2253 UTF-8
Search filters to be passed to the search routines are to be
constructed by hand and should conform to RFC 2254 UTF-8
LDAP URL are to be passed to routines are expected to conform
to RFC 2255 syntax. The
routines can be used to work with LDAP URLs.
Also provided are various utility routines. The
routines are used to sort the entries and values returned via
the ldap search routines.
Also included in the distribution is a set of lightweight Basic
Encoding Rules routines. These routines are used by the LDAP library
routines to encode and decode LDAP protocol elements using the
(slightly simplified) Basic Encoding Rules defined by LDAP. They are
not normally used directly by an LDAP application program except
in the handling of controls and extended operations. The
routines provide a printf and scanf-like interface, as well as
lower-level access. These routines are discussed in