Time sync: add check for fabric removal

src/app/clusters/time-synchronization-server/time-synchronization-server.cpp

@@ -258,6 +258,13 @@ void TimeSynchronizationServer::Init()
     {
         mGranularity = GranularityEnum::kNoTimeGranularity;
     }
+    // This can error, but it's not clear what should happen in this case. For now, just ignore it because we still
+    // want time sync even if we can't register the deletgate here.
+    CHIP_ERROR err = chip::Server::GetInstance().GetFabricTable().AddFabricDelegate(this);
+    if (err != CHIP_NO_ERROR)
+    {
+        ChipLogError(DeviceLayer, "Unable to register Fabric table delegate for time sync");
+    }
 }
 
 CHIP_ERROR TimeSynchronizationServer::SetTrustedTimeSource(const DataModel::Nullable<Structs::TrustedTimeSourceStruct::Type> & tts)
@@ -663,6 +670,17 @@ void TimeSynchronizationServer::ClearEventFlag(TimeSyncEventFlag flag)
     mEventFlag        = static_cast<TimeSyncEventFlag>(eventFlag);
 }
 
+void TimeSynchronizationServer::OnFabricRemoved(const FabricTable & fabricTable, FabricIndex fabricIndex)
+{
+    if (!mTrustedTimeSource.IsNull() && mTrustedTimeSource.Value().fabricIndex == fabricIndex)
+    {
+        DataModel::Nullable<Structs::TrustedTimeSourceStruct::Type> tts;
+        tts.SetNull();
+        TimeSynchronizationServer::Instance().SetTrustedTimeSource(tts);
+        emitMissingTrustedTimeSourceEvent(0);
+    }
+}
+
 namespace {
 
 class TimeSynchronizationAttrAccess : public AttributeAccessInterface

src/app/clusters/time-synchronization-server/time-synchronization-server.h

@@ -26,6 +26,7 @@
 #include <app/server/Server.h>
 #include <app/util/af-types.h>
 #include <app/util/config.h>
+#include <credentials/FabricTable.h>
 #include <lib/core/TLV.h>
 
 #include <app-common/zap-generated/cluster-objects.h>
@@ -60,7 +61,7 @@ enum class TimeSyncEventFlag : uint8_t
     kMissingTTSource = 16,
 };
 
-class TimeSynchronizationServer
+class TimeSynchronizationServer : public FabricTable::Delegate
 {
 public:
     void Init();
@@ -94,6 +95,9 @@ class TimeSynchronizationServer
     TimeSyncEventFlag GetEventFlag(void);
     void ClearEventFlag(TimeSyncEventFlag flag);
 
+    // Fabric Table delegate functions
+    void OnFabricRemoved(const FabricTable & fabricTable, FabricIndex fabricIndex);
+
 private:
     DataModel::Nullable<Structs::TrustedTimeSourceStruct::Type> mTrustedTimeSource;
     TimeSyncDataProvider::TimeZoneObj mTimeZoneObj{ Span<TimeSyncDataProvider::TimeZoneStore>(mTz), 0 };