ldap_open(3) -- Linux man page



ldap_init, 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;


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. One of these two 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 LDAP structure (defined below), 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. See <ldap.h> for more details.

        typedef struct ldap {
                /* ... other stuff you should not mess with ... */
                char            ld_lberoptions;
                int             ld_deref;
        #define LDAP_DEREF_NEVER        0
        #define LDAP_DEREF_SEARCHING    1
        #define LDAP_DEREF_FINDING      2
        #define LDAP_DEREF_ALWAYS       3
                int             ld_timelimit;
                int             ld_sizelimit;
        #define LDAP_NO_LIMIT           0
                int             ld_errno;
                char            *ld_error;
                char            *ld_matched;
                int             ld_refhoplimit;
                unsigned long   ld_options;
        #define LDAP_OPT_REFERRALS      0x00000002 /* set by default */
        #define LDAP_OPT_RESTART        0x00000004
                /* ... other stuff you should not mess with ... */
        } LDAP;

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. At this time, ldap_init() is preferred. ldap_open() will be depreciated in a later release.  


If an error occurs, these routines will return NULL and errno should be set appropriately.  


Options that affect a particular LDAP instance may be set by modifying the ld_options field in the LDAP structure. This field is set to LDAP_OPT_REFERRALS in ldap_open() and ldap_init(), which causes the library to automatically follow referrals to other servers that may be returned in response to an LDAP operation.

The other supported option is LDAP_OPT_RESTART, which if set will cause the LDAP library to restart the select(2) system call when it is interrupted by the system (i.e., errno is set to EINTR). This option is not supported on the Macintosh and under MS-DOS.

An option can be turned off by clearing the appropriate bit in the ld_options field.  


There are other elements in the LDAP structure that you should not change. You should not make any assumptions about the order of elements in the LDAP structure.  


ldap(3), ldap_bind(3), errno(3)  


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