From 72f558fb6e8a46da1d0c59537516bc1110c6f62f Mon Sep 17 00:00:00 2001
From: Simon Duquennoy <simon.duquennoy@ri.se>
Date: Wed, 9 May 2018 14:39:14 -0700
Subject: [PATCH] RPL Classic: make sure no more than one probe gets in queue
 at any given time

---
 os/net/routing/rpl-classic/rpl-dag.c     |  4 +++-
 os/net/routing/rpl-classic/rpl-private.h |  1 +
 os/net/routing/rpl-classic/rpl-timers.c  | 17 ++++++++---------
 os/net/routing/rpl-classic/rpl.c         |  5 +++++
 4 files changed, 17 insertions(+), 10 deletions(-)

diff --git a/os/net/routing/rpl-classic/rpl-dag.c b/os/net/routing/rpl-classic/rpl-dag.c
index 742ef16c4..670a54f3f 100644
--- a/os/net/routing/rpl-classic/rpl-dag.c
+++ b/os/net/routing/rpl-classic/rpl-dag.c
@@ -908,6 +908,8 @@ rpl_select_parent(rpl_dag_t *dag)
 #if RPL_WITH_PROBING
     if(rpl_parent_is_fresh(best)) {
       rpl_set_preferred_parent(dag, best);
+      /* Unschedule any already scheduled urgent probing */
+      dag->instance->urgent_probing_target = NULL;
     } else {
       /* The best is not fresh. Look for the best fresh now. */
       rpl_parent_t *best_fresh = best_parent(dag, 1);
@@ -920,7 +922,7 @@ rpl_select_parent(rpl_dag_t *dag)
       }
       /* Probe the best parent shortly in order to get a fresh estimate */
       dag->instance->urgent_probing_target = best;
-      rpl_schedule_probing(dag->instance);
+      rpl_schedule_probing_now(dag->instance);
     }
 #else /* RPL_WITH_PROBING */
     rpl_set_preferred_parent(dag, best);
diff --git a/os/net/routing/rpl-classic/rpl-private.h b/os/net/routing/rpl-classic/rpl-private.h
index 1259fffeb..5a01c538a 100644
--- a/os/net/routing/rpl-classic/rpl-private.h
+++ b/os/net/routing/rpl-classic/rpl-private.h
@@ -341,6 +341,7 @@ void rpl_schedule_dao_immediately(rpl_instance_t *);
 void rpl_schedule_unicast_dio_immediately(rpl_instance_t *instance);
 void rpl_cancel_dao(rpl_instance_t *instance);
 void rpl_schedule_probing(rpl_instance_t *instance);
+void rpl_schedule_probing_now(rpl_instance_t *instance);
 
 void rpl_reset_dio_timer(rpl_instance_t *);
 void rpl_reset_periodic_timer(void);
diff --git a/os/net/routing/rpl-classic/rpl-timers.c b/os/net/routing/rpl-classic/rpl-timers.c
index c812a8897..97233f574 100644
--- a/os/net/routing/rpl-classic/rpl-timers.c
+++ b/os/net/routing/rpl-classic/rpl-timers.c
@@ -380,14 +380,7 @@ rpl_schedule_unicast_dio_immediately(rpl_instance_t *instance)
 clock_time_t
 get_probing_delay(rpl_dag_t *dag)
 {
-  if(dag != NULL && dag->instance != NULL
-      && dag->instance->urgent_probing_target != NULL) {
-    /* Urgent probing needed (to find out if a neighbor may become preferred parent) */
-    return random_rand() % (CLOCK_SECOND * 10);
-  } else {
-    /* Else, use normal probing interval */
-    return ((RPL_PROBING_INTERVAL) / 2) + random_rand() % (RPL_PROBING_INTERVAL);
-  }
+  return ((RPL_PROBING_INTERVAL) / 2) + random_rand() % (RPL_PROBING_INTERVAL);
 }
 /*---------------------------------------------------------------------------*/
 rpl_parent_t *
@@ -494,7 +487,6 @@ handle_probing_timer(void *ptr)
         );
     /* Send probe, e.g. unicast DIO or DIS */
     RPL_PROBING_SEND_FUNC(instance, target_ipaddr);
-    instance->urgent_probing_target = NULL;
   }
 
   /* Schedule next probing */
@@ -511,5 +503,12 @@ rpl_schedule_probing(rpl_instance_t *instance)
   ctimer_set(&instance->probing_timer, RPL_PROBING_DELAY_FUNC(instance->current_dag),
                   handle_probing_timer, instance);
 }
+/*---------------------------------------------------------------------------*/
+void
+rpl_schedule_probing_now(rpl_instance_t *instance)
+{
+  ctimer_set(&instance->probing_timer, random_rand() % (CLOCK_SECOND * 4),
+                  handle_probing_timer, instance);
+}
 #endif /* RPL_WITH_PROBING */
 /** @}*/
diff --git a/os/net/routing/rpl-classic/rpl.c b/os/net/routing/rpl-classic/rpl.c
index b1905d611..ecbcdc158 100644
--- a/os/net/routing/rpl-classic/rpl.c
+++ b/os/net/routing/rpl-classic/rpl.c
@@ -266,6 +266,11 @@ rpl_link_callback(const linkaddr_t *addr, int status, int numtx)
     if(instance->used == 1 ) {
       parent = rpl_find_parent_any_dag(instance, &ipaddr);
       if(parent != NULL) {
+        /* If this is the neighbor we were probing urgently, mark urgent
+        probing as done */
+        if(instance->urgent_probing_target == parent) {
+          instance->urgent_probing_target = NULL;
+        }
         /* Trigger DAG rank recalculation. */
         PRINTF("RPL: rpl_link_callback triggering update\n");
         parent->flags |= RPL_PARENT_FLAG_UPDATED;