Ticket 408 - create a normalized dn cache

covscan Defect type: FORWARD_NULL
15. 389-ds-base-1.3.1.6/ldap/servers/slapd/dn.c:3036:var_deref_op -
    Dereferencing null pointer "node".
Introduced by commit 1d6dd39fb8b0ef8eb42ec9ef8c3d325e27a3d3c1
Fix: Check if "node" is null or not before referencing.

Reviewed by [email protected] (Thank you, Rich!!)

ldap/servers/slapd/dn.c

@@ -3032,7 +3032,7 @@ ndn_cache_flush()
     int i;
 
     node = ndn_cache->tail;
-    for(i = 0; i < NDN_FLUSH_COUNT && ndn_cache->cache_count > NDN_MIN_COUNT; i++){
+    for(i = 0; node && i < NDN_FLUSH_COUNT && ndn_cache->cache_count > NDN_MIN_COUNT; i++){
         flush_node = node;
         /* update the lru */
         next = node->prev;