[address-resolver] restart address queries when RLOC changes (#4123)

src/core/thread/address_resolver.cpp

@@ -247,6 +247,25 @@ exit:
     return;
 }
 
+void AddressResolver::RestartAddressQueries(void)
+{
+    for (int i = 0; i < kCacheEntries; i++)
+    {
+        Cache &entry = mCache[i];
+
+        if (entry.mState != Cache::kStateQuery)
+        {
+            continue;
+        }
+
+        SendAddressQuery(entry.mTarget);
+
+        entry.mTimeout      = kAddressQueryTimeout;
+        entry.mFailures     = 0;
+        entry.mRetryTimeout = kAddressQueryInitialRetryDelay;
+    }
+}
+
 otError AddressResolver::Resolve(const Ip6::Address &aEid, uint16_t &aRloc16)
 {
     otError error = OT_ERROR_NONE;

src/core/thread/address_resolver.hpp

@@ -125,6 +125,14 @@ public:
      */
     otError Resolve(const Ip6::Address &aEid, Mac::ShortAddress &aRloc16);
 
+    /**
+     * This method restarts any ongoing address queries.
+     *
+     * Any existing address queries will be restarted as if they are being sent for the first time.
+     *
+     */
+    void RestartAddressQueries(void);
+
 private:
     enum
     {

src/core/thread/mle.cpp

@@ -968,15 +968,18 @@ void Mle::SetRloc16(uint16_t aRloc16)
 {
     Get<ThreadNetif>().RemoveUnicastAddress(mMeshLocal16);
 
+    Get<Mac::Mac>().SetShortAddress(aRloc16);
+    Get<Ip6::Mpl>().SetSeedId(aRloc16);
+
     if (aRloc16 != Mac::kShortAddrInvalid)
     {
         // mesh-local 16
         mMeshLocal16.GetAddress().mFields.m16[7] = HostSwap16(aRloc16);
         Get<ThreadNetif>().AddUnicastAddress(mMeshLocal16);
+#ifdef OPENTHREAD_FTD
+        Get<AddressResolver>().RestartAddressQueries();
+#endif
     }
-
-    Get<Mac::Mac>().SetShortAddress(aRloc16);
-    Get<Ip6::Mpl>().SetSeedId(aRloc16);
 }
 
 void Mle::SetLeaderData(uint32_t aPartitionId, uint8_t aWeighting, uint8_t aLeaderRouterId)