When rte_update is called for an identical route, don't announce anything.

Please implement the rte_same hook in your protocols. It should just
compare your metrics stored directly in rte, the rest is done by the core.

TODO

@@ -9,9 +9,6 @@ Core
 
 - tagging of external routes?
 
-- when an identical route is received, don't trigger updates
-
-- configure: --enable-ipv6
 - configure: IPv6 on glibc 2.0?
 
 - Makefile: install target?

nest/protocol.h

@@ -135,11 +135,13 @@ struct proto {
    *	Routing entry hooks (called only for rte's belonging to this protocol):
    *
    *	   rte_better	Compare two rte's and decide which one is better (1=first, 0=second).
+   *       rte_same	Compare two rte's and decide whether they are identical (1=yes, 0=no).
    *	   rte_insert	Called whenever a rte is inserted to a routing table.
    *	   rte_remove	Called whenever a rte is removed from the routing table.
    */
 
   int (*rte_better)(struct rte *, struct rte *);
+  int (*rte_same)(struct rte *, struct rte *);
   void (*rte_insert)(struct network *, struct rte *);
   void (*rte_remove)(struct network *, struct rte *);
 

nest/rt-table.c

@@ -272,6 +272,17 @@ rte_free_quick(rte *e)
   sl_free(rte_slab, e);
 }
 
+static int
+rte_same(rte *x, rte *y)
+{
+  return
+    x->attrs == y->attrs &&
+    x->flags == y->flags &&
+    x->pflags == y->pflags &&
+    x->pref == y->pref &&
+    (!x->attrs->proto->rte_same || x->attrs->proto->rte_same(x, y));
+}
+
 static void
 rte_recalculate(rtable *table, net *net, struct proto *p, rte *new, ea_list *tmpa)
 {
@@ -284,6 +295,14 @@ rte_recalculate(rtable *table, net *net, struct proto *p, rte *new, ea_list *tmp
     {
       if (old->attrs->proto == p)
 	{
+	  if (rte_same(old, new))
+	    {
+	      /* No changes, ignore the new route */
+	      rte_trace_in(D_ROUTES, p, new, "ignored");
+	      rte_free_quick(new);
+	      old->lastmod = now;
+	      return;
+	    }
 	  *k = old->next;
 	  break;
 	}