.TH LDAP_OPEN 3 "RELEASEDATE" "OpenLDAP LDVERSION"
.\" $OpenLDAP$
.\" Copyright 1998-2004 The OpenLDAP Foundation All Rights Reserved.
.\" Copying restrictions apply.  See COPYRIGHT/LICENSE.
.SH NAME
ldap_init, ldap_open \- Initialize the LDAP library and open a connection to an LDAP server
.SH LIBRARY
OpenLDAP LDAP (libldap, -lldap)
.SH SYNOPSIS
.nf
.ft B
#include <ldap.h>
.LP
.ft B
LDAP *ldap_open(host, port)
.ft
char *host;
int port;
.LP
.ft B
LDAP *ldap_init(host, port)
.ft
char *host;
int port;
.SH DESCRIPTION
.LP
.B 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.
.B 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.
.LP
.B ldap_open()
takes \fIhost\fP, the hostname on which the LDAP server is
running, and \fIport\fP, the port number to which to connect.  If the default
IANA-assigned port of 389 is desired, LDAP_PORT should be specified for
\fIport\fP.  The \fIhost\fP parameter may contain a blank-separated list
of hosts to try to connect to, and each host may optionally by of the form
\fIhost:port\fP.  If present, the \fI:port\fP overrides the \fIport\fP
parameter to
.BR ldap_open() .
Upon successfully making a connection to an
LDAP server,
.B ldap_open()
returns a pointer to an LDAP structure (defined below), which
should be passed to subsequent calls to
.BR ldap_bind() ,
.BR 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.
.LP
.nf
.ft tt
	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;
.ft
.fi
.LP
.B
ldap_init()
acts just like
.BR 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,
.B ldap_init()
is preferred.  
.B ldap_open() will be depreciated in a later release.
.SH ERRORS
If an error occurs, these routines will return NULL and errno should be
set appropriately.
.SH OPTIONS
Options that affect a particular LDAP instance may be set by modifying
the \fIld_options\fP field in the LDAP structure.  This field is set
to \fILDAP_OPT_REFERRALS\fP in
.B ldap_open() and
.B ldap_init(),
which causes the library to automatically follow referrals
to other servers that may be returned in response to an LDAP operation.
.LP
The other supported option is \fILDAP_OPT_RESTART\fP, which if set will
cause the LDAP library to restart the
.BR 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.
.LP
An option can be turned off by clearing the appropriate bit in the
\fIld_options\fP field.
.SH NOTES
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.
.SH SEE ALSO
.BR ldap (3),
.BR ldap_bind (3),
.BR errno (3)
.SH ACKNOWLEDGEMENTS
.B OpenLDAP
is developed and maintained by The OpenLDAP Project (http://www.openldap.org/).
.B OpenLDAP
is derived from University of Michigan LDAP 3.3 Release.