Fix custom CSR response.

Author: bzbarsky-apple

examples/platform/linux/testing/CustomCSRResponse.cpp

@@ -28,7 +28,6 @@ using namespace chip;
 using namespace chip::app;
 using namespace chip::app::Clusters::OperationalCredentials::Commands;
 
-#if 0
 constexpr size_t kMaxResponseLength = 900;
 constexpr size_t kCSRNonceLength    = 32;
 
@@ -145,7 +144,8 @@ namespace app {
 namespace DataModel {
 
 template <>
-CHIP_ERROR Encode(TLV::TLVWriter & writer, TLV::Tag tag, const CSRResponse::Type & responseData)
+CHIP_ERROR EncodeResponseCommandPayload(TLV::TLVWriter & writer, TLV::Tag tag, FabricIndex accessingFabricIndex,
+                                        const CSRResponse::Type & responseData)
 {
     auto tag1      = TLV::ContextTag(CSRResponse::Fields::kNOCSRElements);
     auto tag2      = TLV::ContextTag(CSRResponse::Fields::kAttestationSignature);
@@ -163,5 +163,3 @@ CHIP_ERROR Encode(TLV::TLVWriter & writer, TLV::Tag tag, const CSRResponse::Type
 } // namespace DataModel
 } // namespace app
 } // namespace chip
-
-#endif

src/app/CommandHandler.h

@@ -304,7 +304,7 @@ class CommandHandler
 
         CHIP_ERROR EncodeTo(TLV::TLVWriter & writer, TLV::Tag tag, FabricIndex aAccessingFabricIndex) const final
         {
-            return mValue.Encode(writer, tag, aAccessingFabricIndex);
+            return EncodeResponseCommandPayload(writer, tag, aAccessingFabricIndex, mValue);
         }
 
         CHIP_ERROR EncodeTo(TLV::TLVWriter & writer, TLV::Tag tag) const final

src/app/data-model/Encode.h

@@ -253,6 +253,19 @@ CHIP_ERROR EncodeForRead(TLV::TLVWriter & writer, TLV::Tag tag, FabricIndex acce
 #pragma GCC diagnostic pop
 }
 
+/**
+ * @brief
+ *
+ * Encodes a response command payload. This is a templated function to allow
+ * specializations to be created as needed to customize the behavior.
+ */
+template <typename PayloadType>
+CHIP_ERROR EncodeResponseCommandPayload(TLV::TLVWriter & writer, TLV::Tag tag, FabricIndex accessingFabricIndex,
+                                        const PayloadType & payload)
+{
+    return payload.Encode(writer, tag, accessingFabricIndex);
+}
+
 } // namespace DataModel
 } // namespace app
 } // namespace chip