[network-data] synchronize 6LoWPAN Contexts after Leader is reset (#3353)

src/core/thread/network_data_leader.cpp

@@ -429,6 +429,14 @@ otError LeaderBase::SetNetworkData(uint8_t        aVersion,
         RemoveTemporaryData(mTlvs, mLength);
     }
 
+#if OPENTHREAD_FTD
+    // Synchronize internal 6LoWPAN Context ID Set with recently obtained Network Data.
+    if (GetNetif().GetMle().GetRole() == OT_DEVICE_ROLE_LEADER)
+    {
+        GetNetif().GetNetworkDataLeader().UpdateContextsAfterReset();
+    }
+#endif
+
     otDumpDebgNetData("set network data", mTlvs, mLength);
 
     GetNotifier().Signal(OT_CHANGED_THREAD_NETDATA);

src/core/thread/network_data_leader_ftd.cpp

@@ -1167,7 +1167,7 @@ otError Leader::AddBorderRouter(PrefixTlv &aPrefix, BorderRouterTlv &aBorderRout
     }
 
     dstContext->SetCompress();
-    mContextLastUsed[dstContext->GetContextId() - kMinContextId] = 0;
+    StopContextReuseTimer(dstContext->GetContextId());
 
     if (dstBorderRouter == NULL)
     {
@@ -1224,6 +1224,23 @@ otError Leader::FreeContext(uint8_t aContextId)
     return OT_ERROR_NONE;
 }
 
+void Leader::StartContextReuseTimer(uint8_t aContextId)
+{
+    mContextLastUsed[aContextId - kMinContextId] = TimerMilli::GetNow();
+
+    if (mContextLastUsed[aContextId - kMinContextId] == 0)
+    {
+        mContextLastUsed[aContextId - kMinContextId] = 1;
+    }
+
+    mTimer.Start(kStateUpdatePeriod);
+}
+
+void Leader::StopContextReuseTimer(uint8_t aContextId)
+{
+    mContextLastUsed[aContextId - kMinContextId] = 0;
+}
+
 otError Leader::SendServerDataNotification(uint16_t aRloc16)
 {
     otError error      = OT_ERROR_NONE;
@@ -1362,19 +1379,12 @@ otError Leader::RemoveRloc(PrefixTlv &prefix, uint16_t aRloc16, MatchMode aMatch
         if (prefix.GetSubTlvsLength() == sizeof(ContextTlv))
         {
             context->ClearCompress();
-            mContextLastUsed[context->GetContextId() - kMinContextId] = TimerMilli::GetNow();
-
-            if (mContextLastUsed[context->GetContextId() - kMinContextId] == 0)
-            {
-                mContextLastUsed[context->GetContextId() - kMinContextId] = 1;
-            }
-
-            mTimer.Start(kStateUpdatePeriod);
+            StartContextReuseTimer(context->GetContextId());
         }
         else
         {
             context->SetCompress();
-            mContextLastUsed[context->GetContextId() - kMinContextId] = 0;
+            StopContextReuseTimer(context->GetContextId());
         }
     }
 
@@ -1552,6 +1562,41 @@ otError Leader::RemoveContext(PrefixTlv &aPrefix, uint8_t aContextId)
     return OT_ERROR_NONE;
 }
 
+void Leader::UpdateContextsAfterReset(void)
+{
+    PrefixTlv * prefix;
+    ContextTlv *contextTlv;
+
+    // Iterate through Network Data and synchronize missing contexts.
+    for (NetworkDataTlv *cur                                            = reinterpret_cast<NetworkDataTlv *>(mTlvs);
+         cur < reinterpret_cast<NetworkDataTlv *>(mTlvs + mLength); cur = cur->GetNext())
+    {
+        if (cur->GetType() != NetworkDataTlv::kTypePrefix)
+        {
+            continue;
+        }
+
+        prefix     = static_cast<PrefixTlv *>(cur);
+        contextTlv = FindContext(*prefix);
+
+        if (contextTlv == NULL)
+        {
+            continue;
+        }
+
+        mContextUsed |= 1 << contextTlv->GetContextId();
+
+        if (contextTlv->IsCompress())
+        {
+            StopContextReuseTimer(contextTlv->GetContextId());
+        }
+        else
+        {
+            StartContextReuseTimer(contextTlv->GetContextId());
+        }
+    }
+}
+
 void Leader::HandleTimer(Timer &aTimer)
 {
     aTimer.GetOwner<Leader>().HandleTimer();

src/core/thread/network_data_leader_ftd.hpp

@@ -151,6 +151,14 @@ public:
      */
     otError SendServerDataNotification(uint16_t aRloc16);
 
+    /**
+     * This method synchronizes internal 6LoWPAN Context ID Set with recently obtained Thread Network Data.
+     *
+     * Note that this method should be called only by the Leader once after reset.
+     *
+     */
+    void UpdateContextsAfterReset(void);
+
 #if OPENTHREAD_ENABLE_SERVICE
     /**
      * This method scans network data for given service ID and returns pointer to the respective TLV, if present.
@@ -185,6 +193,8 @@ private:
 
     int     AllocateContext(void);
     otError FreeContext(uint8_t aContextId);
+    void    StartContextReuseTimer(uint8_t aContextId);
+    void    StopContextReuseTimer(uint8_t aContextId);
 
     otError RemoveContext(uint8_t aContextId);
     otError RemoveContext(PrefixTlv &aPrefix, uint8_t aContextId);
@@ -232,7 +242,7 @@ private:
                                       MeshCoP::StateTlv::State aState);
 
     /**
-     * Thread Specification Constants
+     * Thread Specification Constants.
      *
      */
     enum
@@ -240,8 +250,9 @@ private:
         kMinContextId        = 1,            ///< Minimum Context ID (0 is used for Mesh Local)
         kNumContextIds       = 15,           ///< Maximum Context ID
         kContextIdReuseDelay = 48 * 60 * 60, ///< CONTEXT_ID_REUSE_DELAY (seconds)
-        kStateUpdatePeriod   = 1000,         ///< State update period in milliseconds
+        kStateUpdatePeriod   = 60 * 1000,    ///< State update period in milliseconds
     };
+
     uint16_t   mContextUsed;
     uint32_t   mContextLastUsed[kNumContextIds];
     uint32_t   mContextIdReuseDelay;