[TE7]:Support read attribute with complex type for general diagnostic…

… cluster (#10641)

* Support read attribute with complex type for general diagnostic cluster

* Update src/app/clusters/general_diagnostics_server/general_diagnostics_server.cpp

Co-authored-by: Boris Zbarsky <bzbarsky@apple.com>

* Encode an empty list if GetNetworkInterfaces fails

Co-authored-by: Boris Zbarsky <bzbarsky@apple.com>

src/app/clusters/general_diagnostics_server/general_diagnostics_server.cpp

@@ -16,15 +16,19 @@
  */
 
 #include <app-common/zap-generated/attributes/Accessors.h>
+#include <app-common/zap-generated/cluster-objects.h>
 #include <app-common/zap-generated/ids/Attributes.h>
 #include <app-common/zap-generated/ids/Clusters.h>
+#include <app/AttributeAccessInterface.h>
 #include <app/util/attribute-storage.h>
+#include <platform/ConnectivityManager.h>
 #include <platform/PlatformManager.h>
 
 using namespace chip;
 using namespace chip::app;
 using namespace chip::app::Clusters;
 using namespace chip::app::Clusters::GeneralDiagnostics::Attributes;
+using chip::DeviceLayer::ConnectivityMgr;
 using chip::DeviceLayer::PlatformManager;
 
 namespace {
@@ -40,6 +44,7 @@ class GeneralDiagosticsAttrAccess : public AttributeAccessInterface
 private:
     template <typename T>
     CHIP_ERROR ReadIfSupported(CHIP_ERROR (PlatformManager::*getter)(T &), AttributeValueEncoder & aEncoder);
+    CHIP_ERROR ReadNetworkInterfaces(AttributeValueEncoder & aEncoder);
 };
 
 template <typename T>
@@ -60,6 +65,32 @@ CHIP_ERROR GeneralDiagosticsAttrAccess::ReadIfSupported(CHIP_ERROR (PlatformMana
     return aEncoder.Encode(data);
 }
 
+CHIP_ERROR GeneralDiagosticsAttrAccess::ReadNetworkInterfaces(AttributeValueEncoder & aEncoder)
+{
+    CHIP_ERROR err = CHIP_NO_ERROR;
+    DeviceLayer::NetworkInterface * netifs;
+
+    if (ConnectivityMgr().GetNetworkInterfaces(&netifs) == CHIP_NO_ERROR)
+    {
+        err = aEncoder.EncodeList([&netifs](const TagBoundEncoder & encoder) -> CHIP_ERROR {
+            for (DeviceLayer::NetworkInterface * ifp = netifs; ifp != nullptr; ifp = ifp->Next)
+            {
+                ReturnErrorOnFailure(encoder.Encode(*ifp));
+            }
+
+            return CHIP_NO_ERROR;
+        });
+
+        ConnectivityMgr().ReleaseNetworkInterfaces(netifs);
+    }
+    else
+    {
+        err = aEncoder.Encode(DataModel::List<EndpointId>());
+    }
+
+    return err;
+}
+
 GeneralDiagosticsAttrAccess gAttrAccess;
 
 CHIP_ERROR GeneralDiagosticsAttrAccess::Read(const ConcreteAttributePath & aPath, AttributeValueEncoder & aEncoder)
@@ -72,6 +103,9 @@ CHIP_ERROR GeneralDiagosticsAttrAccess::Read(const ConcreteAttributePath & aPath
 
     switch (aPath.mAttributeId)
     {
+    case NetworkInterfaces::Id: {
+        return ReadNetworkInterfaces(aEncoder);
+    }
     case RebootCount::Id: {
         return ReadIfSupported(&PlatformManager::GetRebootCount, aEncoder);
     }