Add a neighbor table entry if a DAO is received from a node where we don't yet have a neighbor table entry.

core/net/rpl/rpl-dag.c

@@ -701,8 +701,8 @@ rpl_select_dag(rpl_instance_t *instance, rpl_parent_t *p)
   return best_dag;
 }
 /*---------------------------------------------------------------------------*/
-rpl_parent_t *
-rpl_select_parent(rpl_dag_t *dag)
+static rpl_parent_t *
+best_parent(rpl_dag_t *dag)
 {
   rpl_parent_t *p, *best;
 
@@ -720,6 +720,14 @@ rpl_select_parent(rpl_dag_t *dag)
     p = nbr_table_next(rpl_parents, p);
   }
 
+  return best;
+}
+/*---------------------------------------------------------------------------*/
+rpl_parent_t *
+rpl_select_parent(rpl_dag_t *dag)
+{
+  rpl_parent_t *best = best_parent(dag);
+
   if(best != NULL) {
     rpl_set_preferred_parent(dag, best);
   }
@@ -1289,4 +1297,10 @@ rpl_process_dio(uip_ipaddr_t *from, rpl_dio_t *dio)
   p->dtsn = dio->dtsn;
 }
 /*---------------------------------------------------------------------------*/
+void
+rpl_lock_parent(rpl_parent_t *p)
+{
+  nbr_table_lock(rpl_parents, p);
+}
+/*---------------------------------------------------------------------------*/
 #endif /* UIP_CONF_IPV6 */

core/net/rpl/rpl-icmp6.c

@@ -700,6 +700,33 @@ dao_input(void)
   }
 
   PRINTF("RPL: adding DAO route\n");
+
+  uip_ds6_nbr_t *nbr;
+  if((nbr = uip_ds6_nbr_lookup(&dao_sender_addr)) == NULL) {
+    if((nbr = uip_ds6_nbr_add(&dao_sender_addr,
+                              (uip_lladdr_t *)packetbuf_addr(PACKETBUF_ADDR_SENDER),
+                              0, NBR_REACHABLE)) != NULL) {
+      /* set reachable timer */
+      stimer_set(&nbr->reachable, UIP_ND6_REACHABLE_TIME / 1000);
+      PRINTF("RPL: Neighbor added to neighbor cache ");
+      PRINT6ADDR(&dao_sender_addr);
+      PRINTF(", ");
+      PRINTLLADDR((uip_lladdr_t *)packetbuf_addr(PACKETBUF_ADDR_SENDER));
+      PRINTF("\n");
+    } else {
+      PRINTF("RPL: Out of Memory, dropping DAO from ");
+      PRINT6ADDR(&dao_sender_addr);
+      PRINTF(", ");
+      PRINTLLADDR((uip_lladdr_t *)packetbuf_addr(PACKETBUF_ADDR_SENDER));
+      PRINTF("\n");
+      return;
+    }
+  } else {
+    PRINTF("RPL: Neighbor already in neighbor cache\n");
+  }
+
+  rpl_lock_parent(p);
+
   rep = rpl_add_route(dag, &prefix, prefixlen, &dao_sender_addr);
   if(rep == NULL) {
     RPL_STAT(rpl_stats.mem_overflows++);

core/net/rpl/rpl-private.h

@@ -304,6 +304,9 @@ uip_ds6_route_t *rpl_add_route(rpl_dag_t *dag, uip_ipaddr_t *prefix,
                                int prefix_len, uip_ipaddr_t *next_hop);
 void rpl_purge_routes(void);
 
+/* Lock a parent in the neighbor cache. */
+void rpl_lock_parent(rpl_parent_t *p);
+
 /* Objective function. */
 rpl_of_t *rpl_find_of(rpl_ocp_t);