From 797bead5e54fd07a87cd46d0b9afe0cd38f516e6 Mon Sep 17 00:00:00 2001
From: Simon Duquennoy <simonduq@sics.se>
Date: Mon, 30 Nov 2015 19:17:17 +0100
Subject: [PATCH] RPL: if a neighbor is unreachable, remove routes via this
 neighbor

---
 core/net/rpl/rpl-dag.c   | 24 ++++++++++++++++++++++++
 core/net/rpl/rpl-mrhof.c |  9 +++++++++
 core/net/rpl/rpl-of0.c   |  7 +++++++
 core/net/rpl/rpl.h       |  6 ++++++
 4 files changed, 46 insertions(+)

diff --git a/core/net/rpl/rpl-dag.c b/core/net/rpl/rpl-dag.c
index 89db83750..c4108fd5a 100644
--- a/core/net/rpl/rpl-dag.c
+++ b/core/net/rpl/rpl-dag.c
@@ -210,6 +210,23 @@ rpl_parent_is_fresh(rpl_parent_t *p)
   return link_stats_is_fresh(stats);
 }
 /*---------------------------------------------------------------------------*/
+int
+rpl_parent_is_reachable(rpl_parent_t *p) {
+  if(p == NULL || p->dag == NULL || p->dag->instance == NULL || p->dag->instance->of == NULL) {
+    return 0;
+  } else {
+#ifndef UIP_CONF_ND6_SEND_NA
+    uip_ds6_nbr_t *nbr = rpl_get_nbr(p);
+    /* Exclude links to a neighbor that is not reachable at a NUD level */
+    if(nbr == NULL || nbr->state != NBR_REACHABLE) {
+      return 0;
+    }
+#endif /* UIP_CONF_ND6_SEND_NA */
+    /* If we don't have fresh link information, assume the parent is reachable. */
+    return !rpl_parent_is_fresh(p) || p->dag->instance->of->parent_has_usable_link(p);
+  }
+}
+/*---------------------------------------------------------------------------*/
 static void
 rpl_set_preferred_parent(rpl_dag_t *dag, rpl_parent_t *p)
 {
@@ -1316,6 +1333,13 @@ rpl_process_parent_event(rpl_instance_t *instance, rpl_parent_t *p)
 
   return_value = 1;
 
+  if(uip_ds6_route_is_nexthop(rpl_get_parent_ipaddr(p)) && !rpl_parent_is_reachable(p)) {
+    PRINTF("RPL: Unacceptable link %u, removing routes via: ", rpl_get_parent_link_metric(p));
+    PRINT6ADDR(rpl_get_parent_ipaddr(p));
+    PRINTF("\n");
+    rpl_remove_routes_by_nexthop(rpl_get_parent_ipaddr(p), p->dag);
+  }
+
   if(!acceptable_rank(p->dag, p->rank)) {
     /* The candidate parent is no longer valid: the rank increase resulting
        from the choice of it as a parent would be too high. */
diff --git a/core/net/rpl/rpl-mrhof.c b/core/net/rpl/rpl-mrhof.c
index a818d1c36..c51ac8694 100644
--- a/core/net/rpl/rpl-mrhof.c
+++ b/core/net/rpl/rpl-mrhof.c
@@ -185,6 +185,14 @@ parent_is_acceptable(rpl_parent_t *p)
   return link_metric <= MAX_LINK_METRIC && path_cost <= MAX_PATH_COST;
 }
 /*---------------------------------------------------------------------------*/
+static int
+parent_has_usable_link(rpl_parent_t *p)
+{
+  uint16_t link_metric = parent_link_metric(p);
+  /* Exclude links with too high link metrics  */
+  return link_metric <= MAX_LINK_METRIC;
+}
+/*---------------------------------------------------------------------------*/
 static rpl_parent_t *
 best_parent(rpl_parent_t *p1, rpl_parent_t *p2)
 {
@@ -296,6 +304,7 @@ rpl_of_t rpl_mrhof = {
   dao_ack_callback,
 #endif
   parent_link_metric,
+  parent_has_usable_link,
   parent_path_cost,
   rank_via_parent,
   best_parent,
diff --git a/core/net/rpl/rpl-of0.c b/core/net/rpl/rpl-of0.c
index 16913d8c5..d0bfd1296 100644
--- a/core/net/rpl/rpl-of0.c
+++ b/core/net/rpl/rpl-of0.c
@@ -155,6 +155,12 @@ parent_is_acceptable(rpl_parent_t *p)
       && STEP_OF_RANK(p) <= MAX_STEP_OF_RANK;
 }
 /*---------------------------------------------------------------------------*/
+static int
+parent_has_usable_link(rpl_parent_t *p)
+{
+  return parent_is_acceptable(p);
+}
+/*---------------------------------------------------------------------------*/
 static rpl_parent_t *
 best_parent(rpl_parent_t *p1, rpl_parent_t *p2)
 {
@@ -220,6 +226,7 @@ rpl_of_t rpl_of0 = {
   dao_ack_callback,
 #endif
   parent_link_metric,
+  parent_has_usable_link,
   parent_path_cost,
   rank_via_parent,
   best_parent,
diff --git a/core/net/rpl/rpl.h b/core/net/rpl/rpl.h
index f4efafd50..89bc70ae8 100644
--- a/core/net/rpl/rpl.h
+++ b/core/net/rpl/rpl.h
@@ -162,6 +162,10 @@ typedef struct rpl_instance rpl_instance_t;
  *
  *  Returns the link metric of a parent
  *
+ * parent_has_usable_link(parent)
+ *
+ *  Returns 1 iff we have a usable link to this parent
+ *
  * parent_path_cost(parent)
  *
  *  Returns the path cost of a parent
@@ -200,6 +204,7 @@ struct rpl_of {
   void (*dao_ack_callback)(rpl_parent_t *, int status);
 #endif
   uint16_t (*parent_link_metric)(rpl_parent_t *);
+  int (*parent_has_usable_link)(rpl_parent_t *);
   uint16_t (*parent_path_cost)(rpl_parent_t *);
   rpl_rank_t (*rank_via_parent)(rpl_parent_t *);
   rpl_parent_t *(*best_parent)(rpl_parent_t *, rpl_parent_t *);
@@ -276,6 +281,7 @@ void rpl_remove_header(void);
 uint8_t rpl_invert_header(void);
 const struct link_stats *rpl_get_parent_link_stats(rpl_parent_t *p);
 int rpl_parent_is_fresh(rpl_parent_t *p);
+int rpl_parent_is_reachable(rpl_parent_t *p);
 uint16_t rpl_get_parent_link_metric(rpl_parent_t *p);
 rpl_rank_t rpl_rank_via_parent(rpl_parent_t *p);
 const linkaddr_t *rpl_get_parent_lladdr(rpl_parent_t *p);