added function for checking downward route and added configuration for DAO NACK repair - default off

core/net/rpl/rpl-conf.h

@@ -245,6 +245,17 @@
 #define RPL_WITH_DAO_ACK 1
 #endif /* RPL_CONF_WITH_DAO_ACK */
 
+/*
+ * RPL REPAIR ON DAO NACK. When enabled, DAO NACK will trigger a local
+ * repair in order to quickly find a new parent to send DAO's to.
+ * NOTE: this is too agressive in some cases so use with care.
+ * */
+#ifdef RPL_CONF_RPL_REPAIR_ON_DAO_NACK
+#define RPL_REPAIR_ON_DAO_NACK RPL_CONF_RPL_REPAIR_ON_DAO_NACK
+#else
+#define RPL_REPAIR_ON_DAO_NACK 0
+#endif /* RPL_CONF_RPL_REPAIR_ON_DAO_NACK */
+
 /*
  * Setting the DIO_REFRESH_DAO_ROUTES will make RPL always increase
  * the DTSN (Destination Advertisement Trigger Sequence Number) when

core/net/rpl/rpl-dag.c

@@ -1156,6 +1156,9 @@ global_repair(uip_ipaddr_t *from, rpl_dag_t *dag, rpl_dio_t *dio)
 
   RPL_STAT(rpl_stats.global_repairs++);
 }
+
+void rpl_set_downward_link(uint8_t link);
+
 /*---------------------------------------------------------------------------*/
 void
 rpl_local_repair(rpl_instance_t *instance)
@@ -1174,6 +1177,9 @@ rpl_local_repair(rpl_instance_t *instance)
     }
   }
 
+  /* no downward link anymore */
+  rpl_set_downward_link(0);
+
   rpl_reset_dio_timer(instance);
   /* Request refresh of DAO registrations next DIO */
   RPL_LOLLIPOP_INCREMENT(instance->dtsn_out);

core/net/rpl/rpl-icmp6.c

@@ -89,6 +89,7 @@ void RPL_DEBUG_DAO_OUTPUT(rpl_parent_t *);
 #endif
 
 static uint8_t dao_sequence = RPL_LOLLIPOP_INIT;
+static uint8_t downward = 0;
 
 extern rpl_of_t RPL_OF;
 
@@ -102,6 +103,19 @@ UIP_ICMP6_HANDLER(dio_handler, ICMP6_RPL, RPL_CODE_DIO, dio_input);
 UIP_ICMP6_HANDLER(dao_handler, ICMP6_RPL, RPL_CODE_DAO, dao_input);
 UIP_ICMP6_HANDLER(dao_ack_handler, ICMP6_RPL, RPL_CODE_DAO_ACK, dao_ack_input);
 /*---------------------------------------------------------------------------*/
+
+void
+rpl_set_downward_link(uint8_t link)
+{
+  downward = link;
+}
+
+int
+rpl_has_downward_link()
+{
+  return downward;
+}
+
 #if RPL_WITH_DAO_ACK
 static uip_ds6_route_t *
 find_route_entry_by_dao_ack(uint8_t seq)
@@ -967,6 +981,13 @@ dao_output(rpl_parent_t *parent, uint8_t lifetime)
   instance->my_dao_transmissions = 1;
   ctimer_set(&instance->dao_retransmit_timer, RPL_DAO_RETRANSMISSION_TIMEOUT,
 	     handle_dao_retransmission, parent);
+  if(lifetime == RPL_ZERO_LIFETIME) {
+    rpl_set_downward_link(0);
+  }
+#else
+  /* We know that we have tried to register so now we are assuming
+     that we have a down-link - unless this is a zero lifetime one */
+  rpl_set_downward_link(lifetime != RPL_ZERO_LIFETIME);
 #endif /* RPL_WITH_DAO_ACK */
 }
 /*---------------------------------------------------------------------------*/
@@ -1107,6 +1128,8 @@ dao_ack_input(void)
   if(sequence == instance->my_dao_seqno) {
     PRINTF("RPL: DAO %s for me!\n", status < 128 ? "ACK" : "NACK");
 
+    rpl_set_downward_link(status < 128);
+
     /* always stop the retransmit timer when the ACK arrived */
     ctimer_stop(&instance->dao_retransmit_timer);
 
@@ -1115,11 +1138,14 @@ dao_ack_input(void)
       instance->of->dao_ack_callback(parent, status);
     }
 
+#if RPL_REPAIR_ON_DAO_NACK
     if(status >= RPL_DAO_ACK_UNABLE_TO_ACCEPT) {
       /* failed the DAO transmission - need to remove the default route. */
       /* Trigger a local repair since we can not get our DAO in... */
       rpl_local_repair(instance);
     }
+#endif
+
   } else {
     /* this DAO should be forwarded to another recently registered route */
     uip_ds6_route_t *re;

core/net/rpl/rpl-nbr-policy.c

@@ -49,7 +49,7 @@
 #include "net/ipv6/uip-ds6-nbr.h"
 #include "net/ipv6/uip-ds6-route.h"
 
-#define DEBUG DEBUG_FULL
+#define DEBUG DEBUG_NONE
 #include "net/ip/uip-debug.h"
 
 /*
@@ -63,7 +63,7 @@
  * neighbors and are not only MAC neighbors.
  */
 
-#define MAX_CHILDREN (NBR_TABLE_MAX_NEIGHBORS - 3)
+#define MAX_CHILDREN (NBR_TABLE_MAX_NEIGHBORS - 2)
 #define UIP_IP_BUF       ((struct uip_ip_hdr *)&uip_buf[UIP_LLH_LEN])
 
 static int num_parents; /* any node that are possible parents */

core/net/rpl/rpl.h

@@ -300,5 +300,13 @@ enum rpl_mode rpl_set_mode(enum rpl_mode mode);
  */
 enum rpl_mode rpl_get_mode(void);
 
+
+/**
+ * Get the RPL's best guess on if we have downward link or not.
+ *
+ * \retval 1 if we have a downward link, 0 if not.
+ */
+int rpl_has_downward_link(void);
+
 /*---------------------------------------------------------------------------*/
 #endif /* RPL_H */