ldap_sync_init, ldap_sync_init_refresh_only, ldap_sync_init_refresh_and_persist, ldap_sync_poll — LDAP sync routines
#include <ldap.h>
int
ldap_sync_init( |
ldap_sync_t *ls, |
int mode); |
int
ldap_sync_init_refresh_only( |
ldap_sync_t *ls); |
int
ldap_sync_init_refresh_and_persist( |
ldap_sync_t *ls); |
int
ldap_sync_poll( |
ldap_sync_t *ls); |
ldap_sync_t
*ldap_sync_initialize( |
ldap_sync_t *ls); |
void
ldap_sync_destroy( |
ldap_sync_t *ls, |
int freeit); |
typedef int (*ldap_sync_search_entry_f)(ldap_sync_t *ls, LDAPMessage *msg, struct berval *entryUUID, ldap_sync_refresh_t phase); typedef int (*ldap_sync_search_reference_f)(ldap_sync_t *ls, LDAPMessage *msg); typedef int (*ldap_sync_intermediate_f)(ldap_sync_t *ls, LDAPMessage *msg, BerVarray syncUUIDs, ldap_sync_refresh_t phase); typedef int (*ldap_sync_search_result_f)(ldap_sync_t *ls, LDAPMessage *msg, int refreshDeletes);
These routines provide an interface to the LDAP Content Synchronization operation (RFC 4533). They require an ldap_sync_t structure to be set up with parameters required for various phases of the operation; this includes setting some handlers for special events. All handlers take a pointer to the ldap_sync_t structure as the first argument, and a pointer to the LDAPMessage structure as received from the server by the client library, plus, occasionally, other specific arguments.
The members of the ldap_sync_t structure are:
ls_baseThe search base; by default, the BASE option in ldap.conf(5).
ls_scopeThe search scope (one of LDAP_SCOPE_BASE, LDAP_SCOPE_ONELEVEL, LDAP_SCOPE_SUBORDINATE or
LDAP_SCOPE_SUBTREE; see
ldap.h for details).
ls_filterThe filter (RFC 4515); by default, (objectClass=*).
ls_attrsThe requested attributes; by default NULL, indicating all user
attributes.
ls_timelimitThe requested time limit (in seconds); by default
0, to indicate no
limit.
ls_sizelimitThe requested size limit (in entries); by default
0, to indicate no
limit.
ls_timeoutThe desired timeout during polling with ldap_sync_poll(3). A
value of −1 means that polling
is blocking, so ldap_sync_poll(3)
will not return until a message is received; a value of
0 means that polling
returns immediately, no matter if any response is
available or not; a positive value represents the
timeout the ldap_sync_poll(3)
function will wait for response before returning,
unless a message is received; in that case, ldap_sync_poll(3)
returns as soon as the message is available.
ls_search_entryA function that is called whenever an entry is
returned. The msg argument is the
LDAPMessage that contains the
searchResultEntry; it can be parsed using the regular
client API routines, like ldap_get_dn(3),
ldap_first_attribute(3),
and so on. The entryUUID argument
contains the entryUUID of the entry. The phase argument indicates
the type of operation: one of LDAP_SYNC_CAPI_PRESENT, LDAP_SYNC_CAPI_ADD, LDAP_SYNC_CAPI_MODIFY, LDAP_SYNC_CAPI_DELETE; in case of
LDAP_SYNC_CAPI_PRESENT or
LDAP_SYNC_CAPI_DELETE,
only the DN is contained in the LDAPMessage; in case of LDAP_SYNC_CAPI_MODIFY, the whole
entry is contained in the LDAPMessage, and the application is
responsible of determining the differences between the
new view of the entry provided by the caller and the
data already known.
ls_search_referenceA function that is called whenever a search
reference is returned. The msg argument is the
LDAPMessage that contains the
searchResultReference; it can be parsed using the
regular client API routines, like ldap_parse_reference(3).
ls_intermediateA function that is called whenever something
relevant occurs during the refresh phase of the search,
which is marked by an intermediateResponse message type. The
msg argument is
the LDAPMessage that contains
the intermediate response; it can be parsed using the
regular client API routines, like ldap_parse_intermediate(3).
The syncUUIDs
argument contains an array of UUIDs of the entries that
depends on the value of the phase argument. In case
of LDAP_SYNC_CAPI_PRESENTS, the
"present" phase is being entered; this means that the
following sequence of results will consist in entries
in "present" sync state. In case of LDAP_SYNC_CAPI_DELETES, the "deletes"
phase is being entered; this means that the following
sequence of results will consist in entries in "delete"
sync state. In case of LDAP_SYNC_CAPI_PRESENTS_IDSET, the
message contains a set of UUIDs of entries that are
present; it replaces a "presents" phase. In case of
LDAP_SYNC_CAPI_DELETES_IDSET, the
message contains a set of UUIDs of entries that have
been deleted; it replaces a "deletes" phase. In case of
LDAP_SYNC_CAPI_DONE, a
"presents" phase with "refreshDone" set to "TRUE" has
been returned to indicate that the refresh phase of
refreshAndPersist is over, and the client should start
polling. Except for the LDAP_SYNC_CAPI_PRESENTS_IDSET and
LDAP_SYNC_CAPI_DELETES_IDSET cases,
syncUUIDs is
NULL.
ls_search_resultA function that is called whenever a
searchResultDone is returned. In refreshAndPersist this
can only occur when the server decides that the search
must be interrupted. The msg argument is the
LDAPMessage that contains the
response; it can be parsed using the regular client API
routines, like ldap_parse_result(3).
The refreshDeletes argument
is not relevant in this case; it should always be
−1.
ls_privateA pointer to private data. The client may register here a pointer to data the handlers above may need.
ls_ldA pointer to a LDAP structure that is used to connect to the server. It is the responsibility of the client to initialize the structure and to provide appropriate authentication and security in place.
A ldap_sync_t structure is
initialized by calling ldap_sync_initialize(3).
This simply clears out the contents of an already existing
ldap_sync_t structure, and sets
appropriate values for some members. After that, the caller
is responsible for setting up the connection (member
ls_ld), eventually setting up
transport security (TLS), for binding and any other
initialization. The caller must also fill all the documented
search-related fields of the ldap_sync_t structure.
At the end of a session, the structure can be cleaned up by calling ldap_sync_destroy(3), which takes care of freeing all data assuming it was allocated by ldap_mem*(3) routines. Otherwise, the caller should take care of destroying and zeroing out the documented search-related fields, and call ldap_sync_destroy(3) to free undocumented members set by the API.
The refreshOnly
functionality is obtained by periodically calling ldap_sync_init(3) with mode
set to LDAP_SYNC_REFRESH_ONLY,
or, which is equivalent, by directly calling ldap_sync_init_refresh_only(3).
The state of the search, and the consistency of the search
parameters, is preserved across calls by passing the
ldap_sync_t structure as left by
the previous call.
The refreshAndPersist functionality is
obtained by calling ldap_sync_init(3) with mode
set to LDAP_SYNC_REFRESH_AND_PERSIST, or, which is
equivalent, by directly calling ldap_sync_init_refresh_and_persist(3)
and, after a successful return, by repeatedly polling with
ldap_sync_poll(3) according
to the desired pattern.
A client may insert a call to ldap_sync_poll(3) into an
external loop to check if any modification was returned; in
this case, it might be appropriate to set ls_timeout to 0, or to set it to a finite,
small value. Otherwise, if the client's main purpose consists
in waiting for responses, a timeout of −1 is most
suitable, so that the function only returns after some data
has been received and handled.
All routines return any LDAP error resulting from a
lower-level error in the API calls they are based on, or
LDAP_SUCCESS in case of success. ldap_sync_poll(3) may
return LDAP_SYNC_REFRESH_REQUIRED if a full
refresh is requested by the server. In this case, it is
appropriate to call ldap_sync_init(3) again,
passing the same ldap_sync_t
structure as resulted from any previous call.
Designed and implemented by Pierangelo Masarati, based on RFC 4533 and loosely inspired by syncrepl code in slapd(8).