[IPV6]: ROUTE: Add Router Reachability Probing (RFC4191).

Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 39 insertions, 0 deletions

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index a7030fed1a18..8ba8900c0a5f 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -218,6 +218,42 @@ static __inline__ struct rt6_info *rt6_device_match(struct rt6_info *rt,
         return rt;
 }
 
+#ifdef CONFIG_IPV6_ROUTER_PREF
+static void rt6_probe(struct rt6_info *rt)
+{
+        struct neighbour *neigh = rt ? rt->rt6i_nexthop : NULL;
+        /*
+         * Okay, this does not seem to be appropriate
+         * for now, however, we need to check if it
+         * is really so; aka Router Reachability Probing.
+         *
+         * Router Reachability Probe MUST be rate-limited
+         * to no more than one per minute.
+         */
+        if (!neigh || (neigh->nud_state & NUD_VALID))
+                return;
+        read_lock_bh(&neigh->lock);
+        if (!(neigh->nud_state & NUD_VALID) &&
+            time_after(jiffies, neigh->updated + 60 * HZ)) {
+                struct in6_addr mcaddr;
+                struct in6_addr *target;
+
+                neigh->updated = jiffies;
+                read_unlock_bh(&neigh->lock);
+
+                target = (struct in6_addr *)&neigh->primary_key;
+                addrconf_addr_solict_mult(target, &mcaddr);
+                ndisc_send_ns(rt->rt6i_dev, NULL, target, &mcaddr, NULL);
+        } else
+                read_unlock_bh(&neigh->lock);
+}
+#else
+static inline void rt6_probe(struct rt6_info *rt)
+{
+        return;
+}
+#endif
+
 /*
  * Default Router Selection (RFC 2461 6.3.6)
  */
@@ -287,8 +323,11 @@ static struct rt6_info *rt6_select(struct rt6_info **head, int oif,
                         continue;
 
                 if (m > mpri) {
+                        rt6_probe(match);
                         match = rt;
                         mpri = m;
+                } else {
+                        rt6_probe(rt);
                 }
         }