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NAME |LIBRARY |SYNOPSIS |DESCRIPTION |ERRORS |SEE ALSO |ACKNOWLEDGEMENTS |COLOPHON | |
LDAP_OPEN(3) Library Functions ManualLDAP_OPEN(3)ldap_init, ldap_initialize, ldap_open - Initialize the LDAP library and open a connection to an LDAP server
OpenLDAP LDAP (libldap, -lldap)
#include <ldap.h>LDAP *ldap_open(host, port) char *host; int port;LDAP *ldap_init(host, port) char *host; int port;int ldap_initialize(ldp, uri) LDAP **ldp; char *uri;int ldap_connect(ldp) LDAP *ldp;int ldap_set_urllist_proc(ld, proc, params) LDAP *ld; LDAP_URLLIST_PROC *proc; void *params;int (LDAP_URLLIST_PROC)(ld, urllist, url, params); LDAP *ld; LDAPURLDesc **urllist; LDAPURLDesc **url; void *params;#include <openldap.h>int ldap_init_fd(fd, proto, uri, ldp) ber_socket_t fd; int proto; char *uri; LDAP **ldp;
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()takeshost, the hostname on which the LDAP server is running, andport, the port number to which to connect. If the default IANA-assigned port of 389 is desired, LDAP_PORT should be specified forport. Thehost parameter may contain a blank- separated list of hosts to try to connect to, and each host may optionally by of the formhost:port. If present, the:port overrides theport parameter toldap_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 toldap_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 callingldap_get_option(3) andldap_set_option(3) respectively, whenever possible.ldap_init()acts just likeldap_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 likeldap_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. Theuri parameter may be a comma- or whitespace-separated list of URIs containing only theschema, thehost, and theport fields. Apart fromldap, other (non-standard) recognized values of theschema field areldaps(LDAP over TLS),ldapi(LDAP over IPC), andcldap(connectionless LDAP). If other fields are present, the behavior is undefined. At this time,ldap_open()andldap_init()are deprecated in favor ofldap_initialize(), essentially because the latter allows to specify a schema in the URI and it explicitly returns an error code.ldap_connect()causes a handle created byldap_initialize()to connect to the server. This is useful in situations where a file descriptor is required before a request is performed.ldap_init_fd()allows an LDAP structure to be initialized using an already-opened connection. Theproto 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. Theuri parameter may optionally be provided for informational purposes.ldap_set_urllist_proc()allows to set a functionproc of typeLDAP_URLLIST_PROC that is called when a successful connection can be established. This function receives the list of URIs parsed from theuri string originally passed toldap_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. Ifld is null,proc is set as a global parameter that is inherited by all handlers within the process that are created after the call toldap_set_urllist_proc(). By default, noLDAP_URLLIST_PROC is set. In a multithreaded environment,ldap_set_urllist_proc()must be called before any concurrent operation using the LDAP handle is started. 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 thatldap_get_option() orldap_set_option() be used in the program's main thread before any additional threads are created. Seeldap_get_option(3).
If an error occurs,ldap_open()andldap_init()will return NULL anderrno should be set appropriately.ldap_initialize()andldap_init_fd()will directly return the LDAP code associated to the error (orLDAP_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.
ldap(3),ldap_bind(3),ldap_get_option(3),ldap_set_option(3),lber-sockbuf(3),errno(3)
OpenLDAP Softwareis developed and maintained by The OpenLDAP Project <http://www.openldap.org/>.OpenLDAP Softwareis derived from the University of Michigan LDAP 3.3 Release.
This page is part of theOpenLDAP (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 ⟨https://git.openldap.org/openldap/openldap.git⟩ on 2025-08-11. (At that time, the date of the most recent commit that was found in the repository was 2025-08-05.) 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 isnot part of the original manual page), send a mail to man-pages@man7.orgOpenLDAP LDVERSION RELEASEDATELDAP_OPEN(3)Pages that refer to this page:ldap(3), ldap_bind(3), ldap_dup(3), slapd-meta(5)
HTML rendering created 2025-09-06 byMichael Kerrisk, author ofThe Linux Programming Interface. For details of in-depthLinux/UNIX system programming training courses that I teach, lookhere. Hosting byjambit GmbH. | |