cldap_search_s

- connectionless LDAP search

Synopsis

cc[ flag... ] file... -lldap[ library... ]
#include <lber.h>
#include <ldap.h>

int cldap_search_s(LDAP *ld, char *base, int scope, char *filter,
     char *attrs, int attrsonly, LDAPMessage **res, char *logdn);

Description

The cldap_search_s() function performs an LDAP search using the Connectionless LDAP (CLDAP) protocol.

cldap_search_s() has parameters and behavior identical to that of ldap_search_s(3LDAP), except for the addition of the logdn parameter. logdn should contain a distinguished name to be used only for logging purposed by the LDAP server. It should be in the text format described by RFC 1779, A String Representation of Distinguished Names.

Retransmission Algorithm

cldap_search_s() operates using the CLDAP protocol over udp(7P). Since UDP is a non-reliable protocol, a retry mechanism is used to increase reliability. The cldap_setretryinfo(3LDAP) function can be used to set two retry parameters: tries, a count of the number of times to send a search request and timeout, an initial timeout that determines how long to wait for a response before re-trying. timeout is specified seconds. These values are stored in the ld_cldaptries and ld_cldaptimeout members of the ld LDAP structure, and the default values set in ldap_open(3LDAP) are 4 and 3 respectively. The retransmission algorithm used is:

Step 1

Set the current timeout to ld_cldaptimeout seconds, and the current LDAP server address to the first LDAP server found during the ldap_open(3LDAP) call.

Step 2

Send the search request to the current LDAP server address.

Step 3

Set the wait timeout to the current timeout divided by the number of server addresses found during ldap_open(3LDAP) or to one second, whichever is larger. Wait at most that long for a response; if a response is received, STOP. Note that the wait timeout is always rounded down to the next lowest second.

Step 4

Repeat steps 2 and 3 for each LDAP server address.

Step 5

Set the current timeout to twice its previous value and repeat Steps 2 through 5 a maximum of tries times.

Examples

Assume that the default values for tries and timeout of 4 tries and 3 seconds are used. Further, assume that a space-separated list of two hosts, each with one address, was passed to cldap_open(3LDAP). The pattern of requests sent will be (stopping as soon as a response is received):

  Time        Search Request Sent To:
   +0            Host A try 1
   +1  (0+3/2)        Host B try 1
   +2  (1+3/2)        Host A try 2
   +5  (2+6/2)        Host B try 2
   +8  (5+6/2)        Host A try 3
   +14 (8+12/2)    Host B try 3
   +20 (14+12/2)    Host A try 4
   +32 (20+24/2)    Host B try 4
   +44 (20+24/2)    (give up - no response)

Errors

cldap_search_s() returns LDAP_SUCCESS if a search was successful and the appropriate LDAP error code otherwise. See ldap_error(3LDAP) for more information.

Attributes

See attributes(5) for a description of the following attributes:

See Also

ldap(3LDAP), ldap_error(3LDAP), ldap_search_s(3LDAP), cldap_open(3LDAP), cldap_setretryinfo(3LDAP), cldap_close(3LDAP), attributes(5), udp(7P)