1LDAP(3) Library Functions Manual LDAP(3)
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6 ldap - OpenLDAP Lightweight Directory Access Protocol API
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9 OpenLDAP LDAP (libldap, -lldap)
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12 #include <ldap.h>
13
15 The Lightweight Directory Access Protocol (LDAP) (RFC 4510) provides
16 access to X.500 directory services. These services may be stand-alone
17 or part of a distributed directory service. This client API supports
18 LDAP over TCP (RFC 4511), LDAP over TLS/SSL, and LDAP over IPC (UNIX
19 domain sockets). This API supports SASL (RFC 4513) and Start TLS (RFC
20 4513) as well as a number of protocol extensions. This API is loosely
21 based upon IETF/LDAPEXT C LDAP API draft specification, a (orphaned)
22 work in progress.
23 The OpenLDAP Software package includes a stand-alone server in
25 slapd(8), various LDAP clients, and an LDAP client library used to pro‐
26 vide programmatic access to the LDAP protocol. This man page gives an
27 overview of the LDAP library routines.
28 Both synchronous and asynchronous APIs are provided. Also included are
30 various routines to parse the results returned from these routines.
31 These routines are found in the -lldap library.
32 The basic interaction is as follows. A session handle is created using
34 ldap_initialize(3) and set the protocol version to 3 by calling
35 ldap_set_option(3). The underlying session is established first opera‐
36 tion is issued. This would generally be a Start TLS or Bind operation,
37 or a Search operation to read attributes of the Root DSE. A Start TLS
38 operation is performed by calling ldap_start_tls_s(3). A LDAP bind op‐
39 eration is performed by calling ldap_sasl_bind(3) or one of its
40 friends. A Search operation is performed by calling
41 ldap_search_ext_s(3) or one of its friends.
42 Subsequently, additional operations are performed by calling one of the
44 synchronous or asynchronous routines (e.g., ldap_compare_ext_s(3) or
45 ldap_compare_ext(3) followed by ldap_result(3)). Results returned from
46 these routines are interpreted by calling the LDAP parsing routines
47 such as ldap_parse_result(3). The LDAP association and underlying con‐
48 nection is terminated by calling ldap_unbind_ext(3). Errors can be in‐
49 terpreted by calling ldap_err2string(3).
50
52 This library supports version 3 of the Lightweight Directory Access
53 Protocol (LDAPv3) as defined in RFC 4510. It also supports a variant
54 of version 2 of LDAP as defined by U-Mich LDAP and, to some degree, RFC
55 1777. Version 2 (all variants) are considered obsolete. Version 3
56 should be used instead.
57 For backwards compatibility reasons, the library defaults to version 2.
59 Hence, all new applications (and all actively maintained applications)
60 should use ldap_set_option(3) to select version 3. The library manual
61 pages assume version 3 has been selected.
62
64 All character string input/output is expected to be/is UTF-8 encoded
65 Unicode (version 3.2).
66 Distinguished names (DN) (and relative distinguished names (RDN) to be
68 passed to the LDAP routines should conform to RFC 4514 UTF-8 string
69 representation.
70 Search filters to be passed to the search routines are to be construc‐
72 ted by hand and should conform to RFC 4515 UTF-8 string representation.
73 LDAP URLs to be passed to routines are expected to conform to RFC 4516
75 format. The ldap_url(3) routines can be used to work with LDAP URLs.
76 LDAP controls to be passed to routines can be manipulated using the
78 ldap_controls(3) routines.
79
81 Results obtained from the search routines can be output by hand, by
82 calling ldap_first_entry(3) and ldap_next_entry(3) to step through the
83 entries returned, ldap_first_attribute(3) and ldap_next_attribute(3) to
84 step through an entry's attributes, and ldap_get_values(3) to retrieve
85 a given attribute's values. Attribute values may or may not be dis‐
86 playable.
87
89 Also provided are various utility routines. The ldap_sort(3) routines
90 are used to sort the entries and values returned via the ldap search
91 routines.
92
94 A number of interfaces are now considered deprecated. For instance,
95 ldap_add(3) is deprecated in favor of ldap_add_ext(3). Deprecated in‐
96 terfaces generally remain in the library. The macro LDAP_DEPRECATED
97 can be defined to a non-zero value (e.g., -DLDAP_DEPRECATED=1) when
98 compiling program designed to use deprecated interfaces. It is recom‐
99 mended that developers writing new programs, or updating old programs,
100 avoid use of deprecated interfaces. Over time, it is expected that
101 documentation (and, eventually, support) for deprecated interfaces to
102 be eliminated.
103
105 Also included in the distribution is a set of lightweight Basic Encod‐
106 ing Rules routines. These routines are used by the LDAP library rou‐
107 tines to encode and decode LDAP protocol elements using the (slightly
108 simplified) Basic Encoding Rules defined by LDAP. They are not nor‐
109 mally used directly by an LDAP application program except in the han‐
110 dling of controls and extended operations. The routines provide a
111 printf and scanf-like interface, as well as lower-level access. These
112 routines are discussed in lber-decode(3), lber-encode(3), lber-mem‐
113 ory(3), and lber-types(3).
114
116 ldap_initialize(3) initialize the LDAP library without opening a con‐
117 nection to a server
118 ldap_result(3) wait for the result from an asynchronous operation
120 ldap_abandon_ext(3) abandon (abort) an asynchronous operation
122 ldap_add_ext(3) asynchronously add an entry
124 ldap_add_ext_s(3) synchronously add an entry
126 ldap_sasl_bind(3) asynchronously bind to the directory
128 ldap_sasl_bind_s(3) synchronously bind to the directory
130 ldap_unbind_ext(3) synchronously unbind from the LDAP server and close
132 the connection
133 ldap_unbind(3) and ldap_unbind_s(3) are
135 equivalent to ldap_unbind_ext(3)
136 ldap_memfree(3) dispose of memory allocated by LDAP routines.
138 ldap_compare_ext(3) asynchronously compare to a directory entry
140 ldap_compare_ext_s(3)
142 synchronously compare to a directory entry
143 ldap_delete_ext(3) asynchronously delete an entry
145 ldap_delete_ext_s(3)
147 synchronously delete an entry
148 ld_errno(3) LDAP error indication
150 ldap_errlist(3) list of LDAP errors and their meanings
152 ldap_err2string(3) convert LDAP error indication to a string
154 ldap_extended_operation(3)
156 asynchronously perform an arbitrary extended opera‐
157 tion
158 ldap_extended_operation_s(3)
160 synchronously perform an arbitrary extended opera‐
161 tion
162 ldap_first_attribute(3)
164 return first attribute name in an entry
165 ldap_next_attribute(3)
167 return next attribute name in an entry
168 ldap_first_entry(3) return first entry in a chain of search results
170 ldap_next_entry(3) return next entry in a chain of search results
172 ldap_count_entries(3)
174 return number of entries in a search result
175 ldap_get_dn(3) extract the DN from an entry
177 ldap_get_values_len(3)
179 return an attribute's values with lengths
180 ldap_value_free_len(3)
182 free memory allocated by ldap_get_values_len(3)
183 ldap_count_values_len(3)
185 return number of values
186 ldap_modify_ext(3) asynchronously modify an entry
188 ldap_modify_ext_s(3)
190 synchronously modify an entry
191 ldap_mods_free(3) free array of pointers to mod structures used by
193 ldap_modify_ext(3)
194 ldap_rename(3) asynchronously rename an entry
196 ldap_rename_s(3) synchronously rename an entry
198 ldap_msgfree(3) free results allocated by ldap_result(3)
200 ldap_msgtype(3) return the message type of a message from ldap_re‐
202 sult(3)
203 ldap_msgid(3) return the message id of a message from ldap_re‐
205 sult(3)
206 ldap_search_ext(3) asynchronously search the directory
208 ldap_search_ext_s(3)
210 synchronously search the directory
211 ldap_is_ldap_url(3) check a URL string to see if it is an LDAP URL
213 ldap_url_parse(3) break up an LDAP URL string into its components
215 ldap_sort_entries(3)
217 sort a list of search results
218 ldap_sort_values(3) sort a list of attribute values
220 ldap_sort_strcasecmp(3)
222 case insensitive string comparison
223
225 ldap.conf(5), slapd(8), draft-ietf-ldapext-ldap-c-api-
226 xx.txt <http://www.ietf.org>
227
229 OpenLDAP Software is developed and maintained by The OpenLDAP Project
230 <http://www.openldap.org/>. OpenLDAP Software is derived from the Uni‐
231 versity of Michigan LDAP 3.3 Release.
232 These API manual pages are loosely based upon descriptions provided in
234 the IETF/LDAPEXT C LDAP API Internet Draft, a (orphaned) work in
235 progress.
236OpenLDAP 2.6.6 2023/07/31 LDAP(3)