From 2c21e83d893371ecc1069bf913266e8a504d5f74 Mon Sep 17 00:00:00 2001
From: Robert Lubos <Robert.Lubos@nordicsemi.no>
Date: Thu, 6 Oct 2016 18:04:46 +0200
Subject: [PATCH] Handle router selection jitter timeout only once (#758)

---
 src/core/thread/mle.cpp        |  2 +-
 src/core/thread/mle_router.cpp | 15 ++++++++++-----
 2 files changed, 11 insertions(+), 6 deletions(-)

diff --git a/src/core/thread/mle.cpp b/src/core/thread/mle.cpp
index e5de65500..e05cb521b 100644
--- a/src/core/thread/mle.cpp
+++ b/src/core/thread/mle.cpp
@@ -2165,7 +2165,7 @@ ThreadError Mle::HandleChildIdResponse(const Message &aMessage, const Ip6::Messa
             (mDeviceMode & ModeTlv::kModeFFD) &&
             (numRouters < mMleRouter.GetRouterUpgradeThreshold()))
         {
-            mRouterSelectionJitterTimeout = otPlatRandomGet() % mRouterSelectionJitter;
+            mRouterSelectionJitterTimeout = (otPlatRandomGet() % mRouterSelectionJitter) + 1;
         }
     }
 
diff --git a/src/core/thread/mle_router.cpp b/src/core/thread/mle_router.cpp
index ceb0a1ee1..c2f8138c8 100644
--- a/src/core/thread/mle_router.cpp
+++ b/src/core/thread/mle_router.cpp
@@ -1354,7 +1354,7 @@ ThreadError MleRouter::HandleAdvertisement(const Message &aMessage, const Ip6::M
             (mDeviceMode & ModeTlv::kModeFFD) &&
             (GetActiveRouterCount() < mRouterUpgradeThreshold))
         {
-            mRouterSelectionJitterTimeout = otPlatRandomGet() % mRouterSelectionJitter;
+            mRouterSelectionJitterTimeout = (otPlatRandomGet() % mRouterSelectionJitter) + 1;
             ExitNow();
         }
 
@@ -1680,6 +1680,8 @@ void MleRouter::HandleStateUpdateTimer(void *aContext)
 
 void MleRouter::HandleStateUpdateTimer(void)
 {
+    bool routerStateUpdate = false;
+
     if (mChallengeTimeout > 0)
     {
         mChallengeTimeout--;
@@ -1688,6 +1690,11 @@ void MleRouter::HandleStateUpdateTimer(void)
     if (mRouterSelectionJitterTimeout > 0)
     {
         mRouterSelectionJitterTimeout--;
+
+        if (mRouterSelectionJitterTimeout == 0)
+        {
+            routerStateUpdate = true;
+        }
     }
 
     switch (GetDeviceState())
@@ -1702,8 +1709,7 @@ void MleRouter::HandleStateUpdateTimer(void)
         ExitNow();
 
     case kDeviceStateChild:
-        if (mRouterSelectionJitterTimeout == 0 &&
-            GetActiveRouterCount() < mRouterUpgradeThreshold)
+        if (routerStateUpdate && GetActiveRouterCount() < mRouterUpgradeThreshold)
         {
             // upgrade to Router
             BecomeRouter(ThreadStatusTlv::kTooFewRouters);
@@ -1718,8 +1724,7 @@ void MleRouter::HandleStateUpdateTimer(void)
             BecomeChild(kMleAttachSamePartition);
         }
 
-        if (mRouterSelectionJitterTimeout == 0 &&
-            GetActiveRouterCount() > mRouterDowngradeThreshold)
+        if (routerStateUpdate && GetActiveRouterCount() > mRouterDowngradeThreshold)
         {
             // downgrade to REED
             BecomeChild(kMleAttachSamePartition);