ldap_bind(3)

NAME

ldap_bind, ldap_bind_s, ldap_simple_bind,

ldap_simple_bind_s,
ldap_sasl_bind, ldap_sasl_bind_s, ldap_sasl_inter

active_bind_s,
ldap_parse_sasl_bind_result, ldap_unbind,

ldap_unbind_s,
ldap_unbind_ext, ldap_unbind_ext_s, ldap_set_rebind_proc

- LDAP bind
routines

LIBRARY

OpenLDAP LDAP (libldap, -lldap)

SYNOPSIS

#include <ldap.h>
int ldap_bind(LDAP *ld, const char *who, const char *cred,
       int method);
int  ldap_bind_s(LDAP  *ld,  const  char  *who, const char
*cred,
       int method);
int ldap_simple_bind(LDAP *ld, const char *who, const char
*passwd);
int  ldap_simple_bind_s(LDAP  *ld,  const char *who, const
char *passwd);
int ldap_sasl_bind(LDAP *ld, const char  *dn,  const  char
*mechanism,
       struct berval *cred, LDAPControl *sctrls[],
       LDAPControl *cctrls[], int *msgidp);
int  ldap_sasl_bind_s(LDAP *ld, const char *dn, const char
*mechanism,
       struct berval *cred, LDAPControl *sctrls[],
       LDAPControl      *cctrls[],      struct      berval
**servercredp);
int   ldap_parse_sasl_bind_result(LDAP   *ld,  LDAPMessage
*res,
       struct berval **servercredp, int freeit);
int ldap_sasl_interactive_bind_s(LDAP *ld, const char *dn,
       const char *mechs,
       LDAPControl *sctrls[], LDAPControl *cctrls[],
       unsigned flags, LDAP_SASL_INTERACT_PROC *interact,
       void *defaults);
int  (LDAP_SASL_INTERACT_PROC)(LDAP  *ld,  unsigned flags,
void *defaults, void *sasl_interact);
int ldap_unbind(LDAP *ld);
int ldap_unbind_s(LDAP *ld);
int ldap_unbind_ext(LDAP *ld, LDAPControl *sctrls[],
       LDAPControl *cctrls[]);
int ldap_unbind_ext_s(LDAP *ld, LDAPControl *sctrls[],
       LDAPControl *cctrls[]);
int  ldap_set_rebind_proc  (LDAP   *ld,   LDAP_REBIND_PROC
*ldap_proc, void *params);
int  (LDAP_REBIND_PROC)(LDAP  *ld,  LDAP_CONST  char *url,
ber_tag_t request, ber_int_t msgid, void *params);

DESCRIPTION

These routines provide various interfaces to the LDAP

bind operation.
After an association with an LDAP server is made using

ldap_init(3), an
LDAP bind operation should be performed before other

operations are
attempted over the connection. An LDAP bind is required

when using
Version 2 of the LDAP protocol; it is optional for

Version 3 but is
usually needed due to security considerations.

There are three types of bind calls, ones providing simple

authentication, ones providing SASL authentication, and general

routines capable
of doing either simple or SASL authentication.

SASL (Simple Authentication and Security Layer) that can

negotiate one
of many different kinds of authentication. Both syn

chronous and asynchronous versions of each variant of the bind call are

provided. All
routines take ld as their first parameter, as

returned from
ldap_init(3).

SIMPLE AUTHENTICATION

The simplest form of the bind call is

ldap_simple_bind_s(). It takes
the DN to bind as in who, and the userPassword asso

ciated with the
entry in passwd. It returns an LDAP error in

dication (see
ldap_error(3)). The ldap_simple_bind() call is asyn

chronous, taking
the same parameters but only initiating the bind operation

and returning the message id of the request it sent. The result of

the operation
can be obtained by a subsequent call to ldap_result(3).

GENERAL AUTHENTICATION

The ldap_bind() and ldap_bind_s() routines can be used

when the authentication method to use needs to be selected at runtime.

They both take
an extra method parameter selecting the authentication

method to use.
It should be set to LDAP_AUTH_SIMPLE to select simple

authentication.
ldap_bind() returns the message id of the request

it initiates.
ldap_bind_s() returns an LDAP error indication.

SASL AUTHENTICATION

For SASL binds the server always ignores any provided

DN, so the dn
parameter should always be NULL. ldap_sasl_bind_s()

sends a single
SASL bind request with the given SASL mechanism and cre

dentials in the
cred parameter. The format of the credentials depends on

the particular
SASL mechanism in use. For mechanisms that provide mutu

al authentication the server's credentials will be returned in the

servercredp
parameter. The routine returns an LDAP error in

dication (see
ldap_error(3)). The ldap_sasl_bind() call is asyn

chronous, taking the
same parameters but only sending the request and return

ing the message
id of the request it sent. The result of the operation can

be obtained
by a subsequent call to ldap_result(3). The result must

be additionally parsed by ldap_parse_sasl_bind_result() to obtain any

server credentials sent from the server.

Many SASL mechanisms require multiple message exchanges

to perform a
complete authentication. Applications should

generally use
ldap_sasl_interactive_bind_s() rather than calling

the basic
ldap_sasl_bind() functions directly. The mechs parameter

should contain
a space-separated list of candidate mechanisms to use. If

this parameter is NULL or empty the library will query the supported

SASLMechanisms
attribute from the server's rootDSE for the list of SASL

mechanisms the
server supports. The flags parameter controls the interac

tion used to
retrieve any necessary SASL authentication parameters and

should be one
of:

LDAP_SASL_AUTOMATIC

use defaults if available, prompt otherwise

LDAP_SASL_INTERACTIVE

always prompt

LDAP_SASL_QUIET

never prompt

The interact function uses the provided defaults to

handle requests
from the SASL library for particular authentication pa

rameters. There
is no defined format for the defaults information; it is

up to the
caller to use whatever format is appropriate for the sup

plied interact
function. The sasl_interact parameter comes from the un

derlying SASL
library. When used with Cyrus SASL this is an array of

sasl_interact_t
structures. The Cyrus SASL library will prompt for a vari

ety of inputs,
including:

SASL_CB_GETREALM

the realm for the authentication attempt

SASL_CB_AUTHNAME

the username to authenticate

SASL_CB_PASS

the password for the provided username

SASL_CB_USER

the username to use for proxy authorization

SASL_CB_NOECHOPROMPT

generic prompt for input with input echoing dis

abled

SASL_CB_ECHOPROMPT

generic prompt for input with input echoing enabled

SASL_CB_LIST_END

indicates the end of the array of prompts

See the Cyrus SASL documentation for more details.

REBINDING

The ldap_set_rebind_proc function() sets the process to

use for binding
when an operation returns a referral. This function is

used when an
application needs to bind to another server in order to

follow a referral or search continuation reference.

The function takes ld, the rebind function, and the

params, the arbitrary data like state information which the client might

need to properly rebind. The LDAP_OPT_REFERRALS option in the ld must

be set to ON
for the libraries to use the rebind function. Use the

ldap_set_option
function to set the value.

The rebind function parameters are as follows:

The ld parameter must be used by the application when

binding to the
referred server if the application wants the libraries

to follow the
referral.

The url parameter points to the URL referral string re

ceived from the
LDAP server. The LDAP application can use the

ldap_url_parse(3) function to parse the string into its components.

The request parameter specifies the type of request that

generated the
referral.

The msgid parameter specifies the message ID of the re

quest generating
the referral.

The params parameter is the same value as passed origi

nally to the
ldap_set_rebind_proc() function.

The LDAP libraries set all the parameters when they

call the rebind
function. The application should not attempt to free ei

ther the ld or
the url structures in the rebind function.

The application must supply to the rebind function

the required
authentication information such as, user name, password,

and certificates. The rebind function must use a synchronous bind

method.

UNBINDING

The ldap_unbind() call is used to unbind from the direc

tory, terminate
the current association, and free the resources contained

in the ld
structure. Once it is called, the connection to the

LDAP server is
closed, and the ld structure is invalid. The

ldap_unbind_s() call is
just another name for ldap_unbind(); both of these

calls are synchronous in nature.

The ldap_unbind_ext() and ldap_unbind_ext_s() allows the

operations to
specify controls.

ERRORS

Asynchronous routines will return -1 in case of er

ror, setting the
ld_errno parameter of the ld structure. Synchronous

routines return
whatever ld_errno is set to. See ldap_error(3) for more

information.

NOTES

If an anonymous bind is sufficient for the application,

the rebind process need not be provided. The LDAP libraries with the

LDAP_OPT_REFERRALS option set to ON (default value) will automatically

follow referrals using an anonymous bind.

If the application needs stronger authentication than

an anonymous
bind, you need to provide a rebind process for that

authentication
method. The bind method must be synchronous.

SEE ALSO

ldap(3), ldap_error(3), ldap_open(3),

ldap_set_option(3),
ldap_url_parse(3) RFC 4422 (http://www.rfc-editor.org),

Cyrus SASL

(http://asg.web.cmu.edu/sasl/)

ACKNOWLEDGEMENTS

OpenLDAP Software is developed and maintained by The

OpenLDAP Project
<http://www.openldap.org/>. OpenLDAP Software is derived

from University of Michigan LDAP 3.3 Release.

OpenLDAP 2.4.11 2008/07/16

LDAP_BIND(3)