ldap_open() opens a connection to an LDAP server and allocates an
LDAP structure which is used to identify the connection and to
maintain per-connection information. ldap_init() allocates an LDAP
structure but does not open an initial connection. ldap_initialize()
allocates an LDAP structure but does not open an initial connection.
ldap_init_fd() allocates an LDAP structure using an existing
connection on the provided socket. One of these routines must be
called before any operations are attempted.
ldap_open() takes host, the hostname on which the LDAP server is
running, and port, the port number to which to connect. If the
default IANA-assigned port of 389 is desired, LDAP_PORT should be
specified for port. The host parameter may contain a blank-separated
list of hosts to try to connect to, and each host may optionally by
of the form host:port. If present, the :port overrides the port
parameter to ldap_open(). Upon successfully making a connection to
an LDAP server, ldap_open() returns a pointer to an opaque LDAP
structure, which should be passed to subsequent calls to ldap_bind(),
ldap_search(), etc. Certain fields in the LDAP structure can be set
to indicate size limit, time limit, and how aliases are handled
during operations; read and write access to those fields must occur
by calling ldap_get_option(3) and ldap_set_option(3) respectively,
ldap_init() acts just like ldap_open(), but does not open a
connection to the LDAP server. The actual connection open will occur
when the first operation is attempted.
ldap_initialize() acts like ldap_init(), but it returns an integer
indicating either success or the failure reason, and it allows to
specify details for the connection in the schema portion of the URI.
The uri parameter may be a comma- or whitespace-separated list of
URIs containing only the schema, the host, and the port fields.
Apart from ldap, other (non-standard) recognized values of the schema
field are ldaps (LDAP over TLS), ldapi (LDAP over IPC), and cldap
(connectionless LDAP). If other fields are present, the behavior is
At this time, ldap_open() and ldap_init() are deprecated in favor of
ldap_initialize(), essentially because the latter allows to specify a
schema in the URI and it explicitly returns an error code.
ldap_init_fd() allows an LDAP structure to be initialized using an
already-opened connection. The proto parameter should be one of
LDAP_PROTO_TCP, LDAP_PROTO_UDP, or LDAP_PROTO_IPC for a connection
using TCP, UDP, or IPC, respectively. The value LDAP_PROTO_EXT may
also be specified if user-supplied sockbuf handlers are going to be
used. Note that support for UDP is not implemented unless libldap was
built with LDAP_CONNECTIONLESS defined. The uri parameter may
optionally be provided for informational purposes.
ldap_set_urllist_proc() allows to set a function proc of type
LDAP_URLLIST_PROC that is called when a successful connection can be
established. This function receives the list of URIs parsed from the
uri string originally passed to ldap_initialize(), and the one that
successfully connected. The function may manipulate the URI list;
the typical use consists in moving the successful URI to the head of
the list, so that subsequent attempts to connect to one of the URIs
using the same LDAP handle will try it first. If ld is null, proc is
set as a global parameter that is inherited by all handlers within
the process that are created after the call to
ldap_set_urllist_proc(). By default, no LDAP_URLLIST_PROC is set.
In a multithreaded environment, ldap_set_urllist_proc() must be
called before any concurrent operation using the LDAP handle is
Note: the first call into the LDAP library also initializes the
global options for the library. As such the first call should be
single-threaded or otherwise protected to insure that only one call
is active. It is recommended that ldap_get_option() or
ldap_set_option() be used in the program's main thread before any
additional threads are created. See ldap_get_option(3).
If an error occurs, ldap_open() and ldap_init() will return NULL and
errno should be set appropriately. ldap_initialize() and
ldap_init_fd() will directly return the LDAP code associated to the
error (or LDAP_SUCCESS in case of success); errno should be set as
well whenever appropriate. ldap_set_urllist_proc() returns
LDAP_OPT_ERROR on error, and LDAP_OPT_SUCCESS on success.
This page is part of the OpenLDAP (an open source implementation of
the Lightweight Directory Access Protocol) project. Information
about the project can be found at ⟨http://www.openldap.org/⟩. If you
have a bug report for this manual page, see
⟨http://www.openldap.org/its/⟩. This page was obtained from the
project's upstream Git repository
⟨git://git.openldap.org/openldap.git⟩ on 2017-03-13. If you discover
any rendering problems in this HTML version of the page, or you
believe there is a better or more up-to-date source for the page, or
you have corrections or improvements to the information in this
COLOPHON (which is not part of the original manual page), send a mail
OpenLDAP LDVERSION RELEASEDATE LDAP_OPEN(3)