LDAP

Section: C Library Functions (3)
Updated: 2006/08/19
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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 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 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 protocol 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. 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. Subsequently, other operations are performed by calling one of the synchronous or asynchronous routines (e.g., ldap_search_ext_s(3) or ldap_search_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 association 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 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) 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 conform to RFC 2253 UTF-8 string representation.

Search filters to be passed to the search routines are to be constructed by hand and should conform to RFC 2254 UTF-8 string representation.

LDAP URL are to be passed to routines are expected to conform to RFC 2255 syntax. The ldap_url(3) routines can be used to work with LDAP URLs.  

DISPLAYING RESULTS

Results obtained from the search routines can be output by hand, by calling ldap_first_entry(3) and ldap_next_entry(3) to step through the entries returned, ldap_first_attribute(3) and ldap_next_attribute(3) to step through an entry's attributes, and ldap_get_values(3) to retrieve a given attribute's values. Attribute values may or may not be displayable.  

UTILITY ROUTINES

Also provided are various utility routines. The ldap_sort(3) routines are used to sort the entries and values returned via the ldap search routines.  

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_attribute(3)
return first attribute name in an entry
ldap_next_attribute(3)
return next attribute name in an entry
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

ldap.conf(5), slapd(8), draft-ietf-ldapext-ldap-c-api-xx.txt <http://www.ietf.org>  

ACKNOWLEDGEMENTS

OpenLDAP is developed and maintained by The OpenLDAP Project (http://www.openldap.org/). OpenLDAP is derived from University of Michigan LDAP 3.3 Release.

These API manual pages are loosely based upon descriptions provided in the IETF/LDAPEXT C LDAP API Internet Draft, a (orphaned) work in progress.


 

Index

NAME
LIBRARY
SYNOPSIS
DESCRIPTION
LDAP versions
INPUT and OUTPUT PARAMETERS
DISPLAYING RESULTS
UTILITY ROUTINES
BER LIBRARY
INDEX
SEE ALSO
ACKNOWLEDGEMENTS

linux.jgfs.net manual pages