[network-data] deregister for invalid child on new network data (#4485)

src/core/thread/mle_router.cpp

@@ -2606,6 +2606,24 @@ void MleRouter::HandleNetworkDataUpdateRouter(void)
 
     SynchronizeChildNetworkData();
 
+    // Detect if any server entry with invalid child RLOC16
+    {
+        NetworkData::Iterator iterator = NetworkData::kIteratorInit;
+        uint16_t              rloc16   = Mac::kShortAddrInvalid;
+
+        while (Get<NetworkData::Leader>().GetNextServer(iterator, rloc16) == OT_ERROR_NONE)
+        {
+            if (!IsActiveRouter(rloc16) && RouterIdMatch(GetRloc16(), rloc16) &&
+                mChildTable.FindChild(rloc16, Child::kInStateValid) == NULL)
+            {
+                Get<NetworkData::Leader>().SendServerDataNotification(rloc16);
+                // In Thread 1.1 Specification 5.15.6.1, only one RLOC16 TLV entry may appear in SRV_DATA.ntf.
+                // So break here.
+                break;
+            }
+        }
+    }
+
 exit:
     return;
 }

src/core/thread/network_data.cpp

@@ -1036,6 +1036,110 @@ exit:
     return error;
 }
 
+otError NetworkData::GetNextServer(Iterator &aIterator, uint16_t &aRloc16)
+{
+    otError             error = OT_ERROR_NOT_FOUND;
+    NetworkDataIterator iterator(aIterator);
+    NetworkDataTlv *    cur = reinterpret_cast<NetworkDataTlv *>(mTlvs + iterator.GetTlvOffset());
+    NetworkDataTlv *    end = reinterpret_cast<NetworkDataTlv *>(mTlvs + mLength);
+
+    for (; cur < end; cur = cur->GetNext(), iterator.SetSubTlvOffset(0), iterator.SetEntryIndex(0))
+    {
+        NetworkDataTlv *subCur;
+        NetworkDataTlv *subEnd;
+
+        VerifyOrExit((cur + 1) <= end && cur->GetNext() <= end, error = OT_ERROR_PARSE);
+
+        switch (cur->GetType())
+        {
+        case NetworkDataTlv::kTypePrefix:
+        {
+            PrefixTlv *prefix = static_cast<PrefixTlv *>(cur);
+            subCur            = reinterpret_cast<NetworkDataTlv *>(reinterpret_cast<uint8_t *>(prefix->GetSubTlvs()) +
+                                                        iterator.GetSubTlvOffset());
+            subEnd            = cur->GetNext();
+
+            for (; subCur < subEnd; subCur = subCur->GetNext(), iterator.SetEntryIndex(0))
+            {
+                VerifyOrExit((subCur + 1) <= subEnd && subCur->GetNext() <= subEnd, error = OT_ERROR_PARSE);
+
+                if (subCur->GetType() == NetworkDataTlv::kTypeBorderRouter)
+                {
+                    BorderRouterTlv *borderRouter = static_cast<BorderRouterTlv *>(subCur);
+                    uint8_t          index        = iterator.GetEntryIndex();
+
+                    if (index < borderRouter->GetNumEntries())
+                    {
+                        aRloc16 = borderRouter->GetEntry(index)->GetRloc();
+
+                        iterator.SaveTlvOffset(cur, mTlvs);
+                        iterator.SaveSubTlvOffset(subCur, prefix->GetSubTlvs());
+                        iterator.SetEntryIndex(index + 1);
+
+                        ExitNow(error = OT_ERROR_NONE);
+                    }
+                }
+                else if (subCur->GetType() == NetworkDataTlv::kTypeHasRoute)
+                {
+                    HasRouteTlv *hasRoute = static_cast<HasRouteTlv *>(subCur);
+                    uint8_t      index    = iterator.GetEntryIndex();
+
+                    if (index < hasRoute->GetNumEntries())
+                    {
+                        aRloc16 = hasRoute->GetEntry(index)->GetRloc();
+
+                        iterator.SaveTlvOffset(cur, mTlvs);
+                        iterator.SaveSubTlvOffset(subCur, prefix->GetSubTlvs());
+                        iterator.SetEntryIndex(index + 1);
+
+                        ExitNow(error = OT_ERROR_NONE);
+                    }
+                }
+            }
+
+            break;
+        }
+        case NetworkDataTlv::kTypeService:
+        {
+            ServiceTlv *service = static_cast<ServiceTlv *>(cur);
+            subCur = reinterpret_cast<NetworkDataTlv *>(reinterpret_cast<uint8_t *>(service->GetSubTlvs()) +
+                                                        iterator.GetSubTlvOffset());
+            subEnd = cur->GetNext();
+
+            for (; subCur < subEnd; subCur = subCur->GetNext())
+            {
+                VerifyOrExit((subCur + 1) <= subEnd && subCur->GetNext() <= subEnd, error = OT_ERROR_PARSE);
+
+                if (subCur->GetType() == NetworkDataTlv::kTypeServer)
+                {
+                    ServerTlv *server = static_cast<ServerTlv *>(subCur);
+                    aRloc16           = server->GetServer16();
+
+                    if (subCur->GetNext() >= cur->GetNext())
+                    {
+                        iterator.SaveTlvOffset(cur->GetNext(), mTlvs);
+                        iterator.SetSubTlvOffset(0);
+                    }
+                    else
+                    {
+                        iterator.SaveTlvOffset(cur, mTlvs);
+                        iterator.SaveSubTlvOffset(subCur->GetNext(), service->GetSubTlvs());
+                    }
+
+                    ExitNow(error = OT_ERROR_NONE);
+                }
+            }
+            break;
+        }
+        default:
+            break;
+        }
+    }
+
+exit:
+    return error;
+}
+
 void NetworkData::ClearResubmitDelayTimer(void)
 {
     mLastAttempt.SetValue(0);

src/core/thread/network_data.hpp

@@ -304,6 +304,18 @@ public:
      */
     bool ContainsService(uint8_t aServiceId, uint16_t aRloc16);
 
+    /**
+     * This method provides the next server RLOC16 in the Thread Network Data.
+     *
+     * @param[inout]  aIterator  A reference to the Network Data iterator.
+     * @param[out]    aRloc16    The RLOC16 value.
+     *
+     * @retval OT_ERROR_NONE       Successfully found the next server.
+     * @retval OT_ERROR_NOT_FOUND  No subsequent server exists in the Thread Network Data.
+     *
+     */
+    otError GetNextServer(Iterator &aIterator, uint16_t &aRloc16);
+
     /**
      * This method cancels the data resubmit delay timer.
      *