Test 9.2.12 fixes (#1494)

* Jitter delay before sending Parent Request when becoming a child.

* Copy known route path to Leader and link to Parent when node becomes Router.

A Router did not response to Parent Response before it established route path to the
Leader. This patch fixes it. It uses last known route path.

src/core/thread/mle.cpp

@@ -76,7 +76,6 @@ Mle::Mle(ThreadNetif &aThreadNetif) :
     mLastPartitionRouterIdSequence(0),
     mLastPartitionId(0),
     mParentRequestMode(kMleAttachAnyPartition),
-    mParentLinkQuality(0),
     mParentPriority(0),
     mParentLinkQuality3(0),
     mParentLinkQuality2(0),
@@ -493,7 +492,7 @@ ThreadError Mle::BecomeChild(otMleAttachFilter aFilter)
 
     mNetif.GetMeshForwarder().SetRxOnWhenIdle(true);
 
-    mParentRequestTimer.Start(kParentRequestRouterTimeout);
+    mParentRequestTimer.Start((otPlatRandomGet() % kParentRequestRouterTimeout) + 1);
 
 exit:
     otLogFuncExitErr(error);
@@ -2474,13 +2473,17 @@ exit:
     return error;
 }
 
-bool Mle::IsBetterParent(uint16_t aRloc16, uint8_t aLinkQuality, ConnectivityTlv &aConnectivityTlv) const
+bool Mle::IsBetterParent(uint16_t aRloc16, uint8_t aLinkQuality, ConnectivityTlv &aConnectivityTlv)
 {
     bool rval = false;
 
-    if (aLinkQuality != mParentLinkQuality)
+    uint8_t candidateLinkQualityIn = mParentCandidate.mLinkInfo.GetLinkQuality(mNetif.GetMac().GetNoiseFloor());
+    uint8_t candidateTwoWayLinkQuality = (candidateLinkQualityIn < mParentCandidate.mLinkQualityOut)
+                                         ?  candidateLinkQualityIn : mParentCandidate.mLinkQualityOut;
+
+    if (aLinkQuality != candidateTwoWayLinkQuality)
     {
-        ExitNow(rval = (aLinkQuality > mParentLinkQuality));
+        ExitNow(rval = (aLinkQuality > candidateTwoWayLinkQuality));
     }
 
     if (IsActiveRouter(aRloc16) != IsActiveRouter(mParentCandidate.mValid.mRloc16))
@@ -2641,14 +2644,15 @@ ThreadError Mle::HandleParentResponse(const Message &aMessage, const Ip6::Messag
     mParentCandidate.mLinkInfo.Clear();
     mParentCandidate.mLinkInfo.AddRss(mNetif.GetMac().GetNoiseFloor(), threadMessageInfo->mRss);
     mParentCandidate.mLinkFailures = 0;
+    mParentCandidate.mLinkQualityOut = LinkQualityInfo::ConvertLinkMarginToLinkQuality(linkMarginTlv.GetLinkMargin());
     mParentCandidate.mState = Neighbor::kStateValid;
     mParentCandidate.mKeySequence = aKeySequence;
 
-    mParentLinkQuality = linkQuality;
     mParentPriority = connectivity.GetParentPriority();
     mParentLinkQuality3 = connectivity.GetLinkQuality3();
     mParentLinkQuality2 = connectivity.GetLinkQuality2();
     mParentLinkQuality1 = connectivity.GetLinkQuality1();
+    mParentLeaderCost = connectivity.GetLeaderCost();
     mParentLeaderData = leaderData;
     mParentIsSingleton = connectivity.GetActiveRouters() <= 1;
 

src/core/thread/mle.hpp

@@ -1355,6 +1355,10 @@ protected:
 
     uint8_t mLastPartitionRouterIdSequence;
     uint32_t mLastPartitionId;
+
+protected:
+    uint8_t mParentLeaderCost;
+
 private:
     enum
     {
@@ -1391,7 +1395,7 @@ private:
     ThreadError SendChildIdRequest(void);
     void SendOrphanAnnounce(void);
 
-    bool IsBetterParent(uint16_t aRloc16, uint8_t aLinkQuality, ConnectivityTlv &aConnectivityTlv) const;
+    bool IsBetterParent(uint16_t aRloc16, uint8_t aLinkQuality, ConnectivityTlv &aConnectivityTlv);
     void ResetParentCandidate(void);
 
     MessageQueue mDelayedResponses;
@@ -1426,7 +1430,6 @@ private:
     } mParentRequest;
 
     otMleAttachFilter mParentRequestMode;
-    uint8_t mParentLinkQuality;
     int8_t mParentPriority;
     uint8_t mParentLinkQuality3;
     uint8_t mParentLinkQuality2;

src/core/thread/mle_router.cpp

@@ -936,6 +936,7 @@ ThreadError MleRouter::HandleLinkAccept(const Message &aMessage, const Ip6::Mess
         break;
 
     case Neighbor::kStateInvalid:
+    case Neighbor::kStateValid:
         VerifyOrExit((mChallengeTimeout > 0) && (memcmp(mChallenge, response.GetResponse(), sizeof(mChallenge)) == 0),
                      error = kThreadError_Error);
         break;
@@ -3826,6 +3827,18 @@ void MleRouter::HandleAddressSolicitResponse(Coap::Header *aHeader, Message *aMe
         }
     }
 
+    // Keep route path to the Leader reported by the parent before it is updated.
+    if (mRouters[GetLeaderId()].mCost == 0)
+    {
+        mRouters[GetLeaderId()].mCost = mParentLeaderCost;
+    }
+
+    mRouters[GetLeaderId()].mNextHop = GetRouterId(mParent.mValid.mRloc16);
+
+    // Keep link to the parent in order to response to Parent Requests before new link is established.
+    mRouters[GetRouterId(mParent.mValid.mRloc16)] = mParent;
+    mRouters[GetRouterId(mParent.mValid.mRloc16)].mAllocated = true;
+
     // send link request
     SendLinkRequest(NULL);