Create an AAI registry for PwRPC services to allow registration of cu…

…stom AAI classes (#37351)

* Allow custom AAI registration for PwRPC Reads/Writes. Update PwRPC Writes to look for custom AAIs before using datamodel provider

* Add succes log

* Make TryWriteViaAAI public

* Make TryWriteViaAAI public

* Fix compilation errors

* Fix compilation errors

* Fix compilation errors

* Update examples/common/pigweed/rpc_services/Attributes.h

Co-authored-by: Tennessee Carmel-Veilleux <tennessee.carmelveilleux@gmail.com>

* Add new attribute accessor and registry for PwRPC

* Fix compilation error

* Fix compilation error

* Fix compilation error

* Revert changes

* Revert changes

* Accessors will not be indexed by EndpointId/ClusterId. Caller queries all accessors to satisfy the request and returns as soon as a succes/failure is encountered. Accessors will return 'pw::Status::NotFound()' as a way of hinting the caller 'look for an alternative'. If no accessors were registered or all returned 'NotFound' the fallback path is taken.

* fix compilation bug

* Review comments

* Fix compilation

* Fix nits

* Fix ESP32 compilation

* Update examples/common/pigweed/rpc_services/AccessInterceptor.h

Nit : rename parameter names.

Co-authored-by: Andrei Litvin <andy314@gmail.com>

* Update examples/common/pigweed/rpc_services/AccessInterceptor.h

Review suggestion.

Co-authored-by: Andrei Litvin <andy314@gmail.com>

* Update examples/common/pigweed/rpc_services/AccessInterceptorRegistry.h

Review suggestion.

Co-authored-by: Andrei Litvin <andy314@gmail.com>

* Review comments

* Update examples/common/pigweed/rpc_services/AccessInterceptor.h

---------

Co-authored-by: Tennessee Carmel-Veilleux <tennessee.carmelveilleux@gmail.com>
Co-authored-by: Andrei Litvin <andy314@gmail.com>

examples/common/pigweed/rpc_services/AccessInterceptor.h

@@ -0,0 +1,55 @@
+/*
+ *
+ *    Copyright (c) 2025 Project CHIP Authors
+ *    All rights reserved.
+ *
+ *    Licensed under the Apache License, Version 2.0 (the "License");
+ *    you may not use this file except in compliance with the License.
+ *    You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *    Unless required by applicable law or agreed to in writing, software
+ *    distributed under the License is distributed on an "AS IS" BASIS,
+ *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *    See the License for the specific language governing permissions and
+ *    limitations under the License.
+ */
+
+#pragma once
+
+#include "pw_status/status.h"
+#include <app/AttributeReportBuilder.h>
+#include <app/AttributeValueDecoder.h>
+#include <app/AttributeValueEncoder.h>
+
+namespace chip {
+namespace rpc {
+
+/**
+ * Callback class that clusters can implement in order to interpose custom
+ * interception logic.
+ */
+class PigweedDebugAccessInterceptor
+{
+public:
+    PigweedDebugAccessInterceptor()          = default;
+    virtual ~PigweedDebugAccessInterceptor() = default;
+
+    /**
+     * Callback for writing attributes.
+     *
+     * The implementation can do one of three things:
+     *
+     * Returns:
+     *   - `std::nullopt` if the `path` was not handled by this Interceptor.
+     *     Interceptor MUST NOT have attepted to decode `decoder`.
+     *   - A `::pw::Status` value that is considered the FINAL result of the
+     *     write (i.e. write handled) either with success or failure.
+     */
+    virtual std::optional<::pw::Status> Write(const chip::app::ConcreteDataAttributePath & path,
+                                              chip::app::AttributeValueDecoder & decoder) = 0;
+};
+
+} // namespace rpc
+} // namespace chip

examples/common/pigweed/rpc_services/AccessInterceptorRegistry.h

@@ -0,0 +1,73 @@
+/*
+ *
+ *    Copyright (c) 2025 Project CHIP Authors
+ *    All rights reserved.
+ *
+ *    Licensed under the Apache License, Version 2.0 (the "License");
+ *    you may not use this file except in compliance with the License.
+ *    You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *    Unless required by applicable law or agreed to in writing, software
+ *    distributed under the License is distributed on an "AS IS" BASIS,
+ *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *    See the License for the specific language governing permissions and
+ *    limitations under the License.
+ */
+
+#pragma once
+
+#include "pw_status/status.h"
+#include <pigweed/rpc_services/AccessInterceptor.h>
+#include <set>
+
+namespace chip {
+namespace rpc {
+
+/** @brief Custom debug request interceptors.
+ *
+ *    This class is specifically meant for registering custom Accessors that
+ *    allow mini-handlers to process PigweedRPC read/writes separately from the cluster
+ *    code. It is meant to be used by samples using this PigweedRPC services to allow the RPC
+ *    interface to be used in more ways than simply for example, simulating writes from a Matter
+ *    client at the IM level. Handlers registered here by applications should be attempted before any
+ *    standard processing.
+ */
+class PigweedDebugAccessInterceptorRegistry
+{
+public:
+    /**
+     * Registers an attribute access inteceptor within this registry. Use `Unregister` to
+     * unregister an interceptor that was previously registered.
+     * @param attrOverride - the interceptor to be registered.
+     */
+    void Register(PigweedDebugAccessInterceptor * attrOverride) { mAccessors.insert(attrOverride); }
+
+    void Unregister(PigweedDebugAccessInterceptor * attrOverride)
+    {
+        if (mAccessors.find(attrOverride) == mAccessors.end())
+        {
+            ChipLogError(Support, "Attempt to unregister accessor that is not registered.");
+            return;
+        }
+        mAccessors.erase(attrOverride);
+    }
+
+    const std::set<PigweedDebugAccessInterceptor *> & GetAllAccessors() const { return mAccessors; }
+
+    /**
+     * Returns the singleton instance of the attribute accessor registory.
+     */
+    static PigweedDebugAccessInterceptorRegistry & Instance()
+    {
+        static PigweedDebugAccessInterceptorRegistry instance;
+        return instance;
+    }
+
+private:
+    std::set<PigweedDebugAccessInterceptor *> mAccessors;
+};
+
+} // namespace rpc
+} // namespace chip

examples/common/pigweed/rpc_services/Attributes.h

@@ -33,14 +33,42 @@
 #include <app/data-model-provider/Provider.h>
 #include <app/util/attribute-storage.h>
 #include <app/util/attribute-table.h>
+#include <data-model-providers/codegen/CodegenDataModelProvider.h>
 #include <lib/core/TLV.h>
 #include <lib/core/TLVTags.h>
 #include <lib/core/TLVTypes.h>
+#include <pigweed/rpc_services/AccessInterceptor.h>
+#include <pigweed/rpc_services/AccessInterceptorRegistry.h>
 #include <platform/PlatformManager.h>
+#include <set>
 
 namespace chip {
 namespace rpc {
 
+std::optional<::pw::Status> TryWriteViaAccessor(const chip::app::ConcreteDataAttributePath & path,
+                                                chip::app::AttributeValueDecoder & decoder)
+{
+    std::set<PigweedDebugAccessInterceptor *> accessors = PigweedDebugAccessInterceptorRegistry::Instance().GetAllAccessors();
+
+    for (PigweedDebugAccessInterceptor * accessor : accessors)
+    {
+        std::optional<::pw::Status> result = accessor->Write(path, decoder);
+        if (result.has_value()) // Write was either a success or failure.
+        {
+            return result;
+        }
+        else if (decoder.TriedDecode())
+        {
+            ChipLogError(Support, "Interceptor tried decode but did not return status.");
+            return ::pw::Status::FailedPrecondition();
+        }
+    }
+
+    VerifyOrReturnError(!decoder.TriedDecode(), ::pw::Status::FailedPrecondition());
+
+    return std::nullopt;
+}
+
 // Implementation class for chip.rpc.Attributes.
 class Attributes : public pw_rpc::nanopb::Attributes::Service<Attributes>
 {
@@ -207,6 +235,14 @@ class Attributes : public pw_rpc::nanopb::Attributes::Service<Attributes>
         }
 
         app::AttributeValueDecoder decoder(tlvReader.value(), subjectDescriptor);
+
+        std::optional<::pw::Status> interceptResult = TryWriteViaAccessor(write_request.path, decoder);
+        if (interceptResult.has_value())
+        {
+            return *interceptResult;
+        }
+        ChipLogProgress(Support, "No custom PigweedRPC Attribute Accessor registration found, using fake write access.");
+
         app::DataModel::ActionReturnStatus result = provider->WriteAttribute(write_request, decoder);
 
         if (!result.IsSuccess())