LDAP(3) Library Functions Manual LDAP(3)
NAME
ldap - OpenLDAP Lightweight Directory Access Protocol API
LIBRARY
OpenLDAP LDAP (libldap, -lldap)
SYNOPSIS
#include <ldap.h>
DESCRIPTION
The Lightweight Directory Access Protocol (LDAP) (RFC 4510) 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 (RFC 4511), LDAP over TLS/SSL, and LDAP over IPC (UNIX domain sockets). This API supports SASL (RFC
4513) and Start TLS (RFC 4513) 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 slapd(8), 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 created using ldap_initialize(3) and set the proto‐
col version to 3 by calling ldap_set_option(3). The underlying session is established first operation is
issued. This would generally be a Start TLS or Bind operation, or a Search operation to read attributes of
the Root DSE. A Start TLS operation is performed by calling ldap_start_tls_s(3). A LDAP bind operation is
performed by calling ldap_sasl_bind(3) or one of its friends. A Search operation is performed by calling
ldap_search_ext_s(3) or one of its friends.
Subsequently, additional operations are performed by calling one of the synchronous or asynchronous routines
(e.g., ldap_compare_ext_s(3) or ldap_compare_ext(3) followed by ldap_result(3)). Results returned from these
routines are interpreted by calling the LDAP parsing routines such as ldap_parse_result(3). The LDAP associa‐
tion and underlying connection is terminated by calling ldap_unbind_ext(3). Errors can be interpreted by
calling ldap_err2string(3).
LDAP versions
This library supports version 3 of the Lightweight Directory Access Protocol (LDAPv3) as defined in RFC 4510.
It also supports a variant of version 2 of LDAP as defined by U-Mich LDAP and, to some degree, RFC 1777. Ver‐
sion 2 (all variants) are considered 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) should use ldap_set_option(3) 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 con‐
form to RFC 4514 UTF-8 string representation.
Search filters to be passed to the search routines are to be constructed by hand and should conform to RFC
4515 UTF-8 string representation.
LDAP URLs to be passed to routines are expected to conform to RFC 4516 format. The ldap_url(3) routines can
be used to work with LDAP URLs.
DEPRECATED INTERFACES
A number of interfaces are now considered deprecated. For instance, ldap_add(3) is deprecated in favor of
ldap_add_ext(3). Deprecated interfaces generally remain in the library. The macro LDAP_DEPRECATED can be
defined to a non-zero value (e.g., -DLDAP_DEPRECATED=1) when compiling program designed to use deprecated
interfaces. It is recommended that developers writing new programs, or updating old programs, avoid use of
deprecated interfaces. Over time, it is expected that documentation (and, eventually, support) for deprecated
interfaces to be eliminated.
BER LIBRARY
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 lber-decode(3), lber-encode(3),
lber-memory(3), and lber-types(3).
INDEX
ldap_initialize(3) initialize the LDAP library without opening a connection to a server
ldap_result(3) wait for the result from an asynchronous operation
ldap_abandon_ext(3) abandon (abort) an asynchronous operation
ldap_add_ext(3) asynchronously add an entry
ldap_add_ext_s(3) synchronously add an entry
ldap_sasl_bind(3) asynchronously bind to the directory
ldap_sasl_bind_s(3) synchronously bind to the directory
ldap_unbind_ext(3) synchronously unbind from the LDAP server and close the connection
ldap_unbind(3) and ldap_unbind_s(3) are
equivalent to ldap_unbind_ext(3)
ldap_memfree(3) dispose of memory allocated by LDAP routines.
ldap_compare_ext(3) asynchronously compare to a directory entry
ldap_compare_ext_s(3)
synchronously compare to a directory entry
ldap_delete_ext(3) asynchronously delete an entry
ldap_delete_ext_s(3)
synchronously delete an entry
ld_errno(3) LDAP error indication
ldap_errlist(3) list of LDAP errors and their meanings
ldap_err2string(3) convert LDAP error indication to a string
ldap_first_entry(3) return first entry in a chain of search results
ldap_next_entry(3) return next entry in a chain of search results
ldap_count_entries(3)
return number of entries in a search result
ldap_get_dn(3) extract the DN from an entry
ldap_get_values_len(3)
return an attribute's values with lengths
ldap_value_free_len(3)
free memory allocated by ldap_get_values_len(3)
ldap_count_values_len(3)
return number of values
ldap_modify_ext(3) asynchronously modify an entry
ldap_modify_ext_s(3)
synchronously modify an entry
ldap_mods_free(3) free array of pointers to mod structures used by ldap_modify_ext(3)
ldap_rename(3) asynchronously rename an entry
ldap_rename_s(3) synchronously rename an entry
ldap_msgfree(3) free results allocated by ldap_result(3)
ldap_msgtype(3) return the message type of a message from ldap_result(3)
ldap_msgid(3) return the message id of a message from ldap_result(3)
ldap_search_ext(3) asynchronously search the directory
ldap_search_ext_s(3)
synchronously search the directory
ldap_is_ldap_url(3) check a URL string to see if it is an LDAP URL
ldap_url_parse(3) break up an LDAP URL string into its components
ldap_sort_entries(3)
sort a list of search results
ldap_sort_values(3) sort a list of attribute values
ldap_sort_strcasecmp(3)
case insensitive string comparison
SEE ALSO
OpenLDAP 2.4.40 2014/09/20 LDAP(3)
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