cache: event_filter() cache operation to filter notifications

Certain notifications need to be filtered out and should not be applied to
a cache when a cache is handled by a cache manager.

2 files changed, 13 insertions, 0 deletions

diff --git a/include/netlink/cache-api.h b/include/netlink/cache-api.h
index efae2ed..1b3d099 100644
--- a/include/netlink/cache-api.h
+++ b/include/netlink/cache-api.h
@@ -201,6 +201,13 @@ struct nl_cache_ops
 	int   (*co_msg_parser)(struct nl_cache_ops *, struct sockaddr_nl *,
 			       struct nlmsghdr *, struct nl_parser_param *);
 
+	/**
+	 * Called whenever a notification has been parsed into an object and
+	 * is considered for inclusion into a cache. Must return NL_SKIP if
+	 * the object should not be included in the cache.
+	 */
+	int   (*co_event_filter)(struct nl_cache *, struct nl_object *obj);
+
 	/** Object operations */
 	struct nl_object_ops *	co_obj_ops;
 
diff --git a/lib/cache_mngr.c b/lib/cache_mngr.c
index cfa676b..cf5a951 100644
--- a/lib/cache_mngr.c
+++ b/lib/cache_mngr.c
@@ -89,12 +89,18 @@
 static int include_cb(struct nl_object *obj, struct nl_parser_param *p)
 {
 	struct nl_cache_assoc *ca = p->pp_arg;
+	struct nl_cache_ops *ops = ca->ca_cache->c_ops;
 
 	NL_DBG(2, "Including object %p into cache %p\n", obj, ca->ca_cache);
 #ifdef NL_DEBUG
 	if (nl_debug >= 4)
 		nl_object_dump(obj, &nl_debug_dp);
 #endif
+
+	if (ops->co_event_filter)
+		if (ops->co_event_filter(ca->ca_cache, obj) != NL_OK)
+			return 0;
+
 	return nl_cache_include(ca->ca_cache, obj, ca->ca_change, ca->ca_change_data);
 }