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NAME
ldap_bind, ldap_bind_s, ldap_simple_bind, ldap_simple_bind_s,
ldap_sasl_bind, ldap_sasl_bind_s, ldap_sasl_interactive_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_interactive_bind(LDAP *ld, const char *dn,
const char *mechs,
LDAPControl *sctrls[], LDAPControl *cctrls[],
unsigned flags, LDAP_SASL_INTERACT_PROC *interact,
void *defaults, LDAPMessage *result,
const char **rmechp, int *msgidp);
int (LDAP_SASL_INTERACT_PROC)(LDAP *ld, unsigned flags, void *defaults
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
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
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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) can negotiate one of many different kinds of
authentication. Both synchronous 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 associated with the
entry in passwd. It returns an LDAP error indication (see
ldap_error(3)). The ldap_simple_bind() call is asynchronous, 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). The
ldap_sasl_bind_s() and asynchronous ldap_sasl_bind() functions can
also be used to make a simple bind by using LDAP_SASL_SIMPLE as the
SASL mechanism.
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 credentials in the
cred parameter. The format of the credentials depends on the
particular SASL mechanism in use. For mechanisms that provide mutual
authentication the server's credentials will be returned in the
servercredp parameter. The routine returns an LDAP error indication
(see ldap_error(3)). The ldap_sasl_bind() call is asynchronous,
taking the same parameters but only sending the request 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). The result must
be additionally parsed by ldap_parse_sasl_bind_result() to obtain any
server credentials sent from the server.
Any returned server credentials should be freed using ber_bvfree().
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
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contain a space-separated list of candidate mechanisms to use. If this
parameter is NULL or empty the library will query the
supportedSASLMechanisms attribute from the server's rootDSE for the
list of SASL mechanisms the server supports. The flags parameter
controls the interaction 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 parameters. There is no defined format for the
defaults information; it is up to the caller to use whatever
format is appropriate for the supplied interact function. The
sasl_interact parameter comes from the underlying SASL library.
When used with Cyrus SASL this is an array of sasl_interact_t
structures. The Cyrus SASL library will prompt for a variety 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 disabled
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. Applications which need to
manage connections asynchronously may use
ldap_sasl_interactive_bind() instead of the synchronous version.
A valid mechs parameter must be supplied, otherwise the library
will be forced to query the server for a list of supported
mechanisms, and this query will be performed synchronously. The
other parameters are the same as for the synchronous function,
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with three additional parameters. The actual SASL mechanism that
was used, and the message ID for use with ldap_result() will be
returned in rmechp and msgidp, respectively. The value in rmechp
must not be modified by the caller and must be passed back on
each subsequent call. The message obtained from ldap_result()
must be passed in the result parameter. This parameter must be
NULL when initiating a new Bind. The caller must free the result
message after each call using ldap_msgfree(). The
ldap_sasl_interactive_bind() function returns an LDAP result
code. If the code is LDAP_SASL_BIND_IN_PROGRESS then the Bind is
not complete yet, and this function must be called again with the
next result from the server.
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
received 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 request
generating the referral. The params parameter is the same value as
passed originally 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 either 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 directory, 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 error, setting the
ld_errno parameter of the ld structure. Synchronous routines return
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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
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