Minor rte/rta interface changes:

o  rte can now contain a pointer to both cached and uncached rta. Protocols
     which don't need their own attribute caching can now just fill-in a rta,
     link it to rte without any calls to attribute cache and call rte_update()
     which will replace rte->attrs by a cached copy.

  o  In order to support this, one of previously pad bytes in struct rta
     now holds new attribute flags (RTAF_CACHED). If you call rte_update()
     with uncached rta, you _must_ clear these flags. In other cases rta_lookup()
     sets it appropriately.

  o  Added rte_free() which is useful when you construct a rte and then the
     circumstances change and you decide not to use it for an update. (Needed
     for temporary rte's in kernel syncer...)

nest/route.h

@@ -122,6 +122,7 @@ rte *rte_get_temp(struct rtattr *);
 void rte_update(net *net, struct proto *p, rte *new);
 void rte_discard(rte *old);
 void rte_dump(rte *);
+void rte_free(rte *);
 void rt_dump(rtable *);
 void rt_dump_all(void);
 void rt_feed_baby(struct proto *p);
@@ -145,6 +146,7 @@ typedef struct rtattr {
   byte dest;				/* Route destination type (RTD_...) */
   byte tos;				/* TOS of this route */
   byte flags;				/* Route flags (RTF_...) */
+  byte aflags;				/* Attribute cache flags (RTAF_...) */
   ip_addr gw;				/* Next hop */
   ip_addr from;				/* Advertising router */
   struct iface *iface;			/* Outgoing interface */
@@ -180,6 +182,8 @@ typedef struct rtattr {
 #define RTF_EXTERIOR 1			/* Learned via exterior protocol */
 #define RTF_TAGGED 2			/* Tagged external route learned via IGP */
 
+#define RTAF_CACHED 1			/* This is a cached rta */
+
 /*
  *	Extended Route Attributes
  */

nest/rt-attr.c

@@ -116,6 +116,7 @@ rta_lookup(rta *o)
     if (rta_same(r, o))
       return rta_clone(r);
   r = rta_copy(o);
+  r->aflags = RTAF_CACHED;
   r->next = first_rta;
   first_rta = r;
   return r;
@@ -144,6 +145,8 @@ rta_dump(rta *a)
     debug(" EXT");
   if (a->flags & RTF_TAGGED)
     debug(" TAG");
+  if (!(a->aflags & RTAF_CACHED))
+    debug(" !CACHED");
   debug(" <-%I", a->from);
   if (a->dest == RTD_ROUTER)
     debug(" ->%I", a->gw);

nest/rt-table.c

@@ -136,8 +136,16 @@ rt_feed_baby(struct proto *p)
     }
 }
 
-static inline void
+void
 rte_free(rte *e)
+{
+  if (e->attrs->aflags & RTAF_CACHED)
+    rta_free(e->attrs);
+  sl_free(rte_slab, e);
+}
+
+static inline void
+rte_free_quick(rte *e)
 {
   rta_free(e->attrs);
   sl_free(rte_slab, e);
@@ -150,6 +158,9 @@ rte_update(net *net, struct proto *p, rte *new)
   rte *old = NULL;
   rte **k, *r, *s;
 
+  if (new && !(new->attrs->aflags & RTAF_CACHED)) /* Need to copy attributes */
+    new->attrs = rta_lookup(new->attrs);
+
   k = &net->routes;			/* Find and remove original route from the same protocol */
   while (old = *k)
     {
@@ -202,7 +213,7 @@ rte_update(net *net, struct proto *p, rte *new)
     {
       if (p->rte_remove)
 	p->rte_remove(net, old);
-      rte_free(old);
+      rte_free_quick(old);
     }
   if (new)
     {