Inet: Split InetLayer class (#12291)

#### Problem

This is a step toward #7715 _Virtualize System and Inet interfaces_
for mockability, building on recent virtualization of Inet endpoints
and changes to object allocation pools.

The `InetLayer` class acts as a factory for `UDPEndPoint` and `TCPEndPoint`.
Merely making its methods virtual would result in an unacceptable code
size increase for applications that do not use TCP on platforms that
offer it, since the vtable would introduce a dependency that normal
linking doesn't remove.

#### Change overview

- Split the `EndPoint` factory/iteration code into its own class,
  `EndPointManager`. `InetLayer` remains as a stub wrapper for the pair
  of Managers.
- Move the code for TCP idle timeout from `InetLayer` to `TCPEndPoint`.
- Move `IPPacketInfo` from `InetLayer.h` to its own files.

**NOTE** that applications that use CHIP TCP must now explicitly initialize
it via `InetLayer::InitTCP()`.

#### Testing

CI; no changes to external functionality. Tests revised where necessary
to initialize TCP.

src/credentials/FabricTable.cpp

@@ -22,6 +22,7 @@
 #include "FabricTable.h"
 
 #include <lib/core/CHIPEncoding.h>
+#include <lib/support/BufferWriter.h>
 #include <lib/support/CHIPMem.h>
 #include <lib/support/CHIPMemString.h>
 #include <lib/support/SafeInt.h>

src/credentials/tests/TestFabricTable.cpp

@@ -33,7 +33,6 @@
 #include <stdarg.h>
 
 using namespace chip;
-using namespace Transport;
 
 static const uint8_t sTestRootCert[] = {
     0x15, 0x30, 0x01, 0x08, 0x59, 0xea, 0xa6, 0x32, 0x94, 0x7f, 0x54, 0x1c, 0x24, 0x02, 0x01, 0x37, 0x03, 0x27, 0x14, 0x01, 0x00,

src/include/platform/CHIPDeviceEvent.h

@@ -313,7 +313,7 @@ typedef void (*AsyncWorkFunct)(intptr_t arg);
 #endif // defined(CHIP_DEVICE_LAYER_TARGET)
 
 #include <ble/BleConfig.h>
-#include <inet/InetLayer.h>
+#include <inet/InetInterface.h>
 #include <lib/support/LambdaBridge.h>
 #include <system/SystemEvent.h>
 #include <system/SystemLayer.h>

src/include/platform/CHIPDeviceLayer.h

@@ -47,6 +47,8 @@ void SetSystemLayerForTesting(System::LayerImpl * layer);
 
 // These functions are defined in src/platform/Globals.cpp
 chip::Inet::InetLayer & InetLayer();
+chip::Inet::EndPointManager<Inet::UDPEndPoint> * UDPEndPointManager();
+chip::Inet::EndPointManager<Inet::TCPEndPoint> * TCPEndPointManager();
 chip::System::Layer & SystemLayer();
 
 #if CHIP_SYSTEM_CONFIG_USE_SOCKETS

src/include/platform/internal/GenericPlatformManagerImpl.cpp

@@ -81,7 +81,7 @@ CHIP_ERROR GenericPlatformManagerImpl<ImplClass>::_InitChipStack()
     SuccessOrExit(err);
 
     // Initialize the CHIP Inet layer.
-    err = InetLayer().Init(SystemLayer(), nullptr);
+    err = InetLayer().Init(SystemLayer(), UDPEndPointManager());
     if (err != CHIP_NO_ERROR)
     {
         ChipLogError(DeviceLayer, "InetLayer initialization failed: %s", ErrorStr(err));

src/inet/BUILD.gn

@@ -72,6 +72,8 @@ static_library("inet") {
     "IPAddress-StringFuncts.cpp",
     "IPAddress.cpp",
     "IPAddress.h",
+    "IPPacketInfo.cpp",
+    "IPPacketInfo.h",
     "IPPrefix.cpp",
     "IPPrefix.h",
     "Inet.h",

src/inet/EndPointBasis.h

@@ -25,30 +25,55 @@
 #pragma once
 
 #include <inet/InetConfig.h>
+#include <lib/core/ReferenceCounted.h>
 #include <lib/support/DLLUtil.h>
 
 namespace chip {
+
+namespace System {
+class Layer;
+} // namespace System
+
 namespace Inet {
 
-class InetLayer;
+template <typename EndPointType>
+class EndPointManager;
+
+template <typename EndPointType>
+class EndPointDeletor;
 
 /**
  * Basis of internet transport endpoint classes.
  */
-class DLL_EXPORT EndPointBase
+template <typename EndPointType>
+class DLL_EXPORT EndPointBasis : public ReferenceCounted<EndPointType, EndPointDeletor<EndPointType>>
 {
 public:
-    EndPointBase(InetLayer & aInetLayer, void * aAppState = nullptr) : mAppState(aAppState), mInetLayer(aInetLayer) {}
+    using EndPoint = EndPointType;
+
+    EndPointBasis(EndPointManager<EndPoint> & endPointManager) : mAppState(nullptr), mEndPointManager(endPointManager) {}
 
     /**
-     *  Returns a reference to the Inet layer object that owns this basis object.
+     *  Returns a reference to the endpoint fatory that owns this basis object.
      */
-    InetLayer & Layer() const { return mInetLayer; }
+    EndPointManager<EndPoint> & GetEndPointManager() const { return mEndPointManager; }
+
+    /**
+     *  Returns a reference to the System::Layer associated with this object.
+     */
+    chip::System::Layer & GetSystemLayer() const { return mEndPointManager.SystemLayer(); }
 
     void * mAppState;
 
 private:
-    InetLayer & mInetLayer; /**< InetLayer object that owns this object. */
+    EndPointManager<EndPoint> & mEndPointManager; /**< Factory that owns this object. */
+};
+
+template <typename EndPointType>
+class EndPointDeletor
+{
+public:
+    static void Release(EndPointType * obj) { obj->GetEndPointManager().DeleteEndPoint(obj); }
 };
 
 } // namespace Inet

src/inet/IPAddress-StringFuncts.cpp

@@ -30,7 +30,7 @@
 #include <stdint.h>
 #include <string.h>
 
-#include <inet/InetLayer.h>
+#include <inet/IPAddress.h>
 #include <lib/support/CodeUtils.h>
 
 #if !CHIP_SYSTEM_CONFIG_USE_LWIP

src/inet/IPPacketInfo.cpp

@@ -0,0 +1,34 @@
+/*
+ *
+ *    Copyright (c) 2020-2021 Project CHIP Authors
+ *    Copyright (c) 2013-2017 Nest Labs, Inc.
+ *
+ *    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.
+ */
+
+#include "IPPacketInfo.h"
+
+namespace chip {
+namespace Inet {
+
+void IPPacketInfo::Clear()
+{
+    SrcAddress  = IPAddress::Any;
+    DestAddress = IPAddress::Any;
+    Interface   = InterfaceId::Null();
+    SrcPort     = 0;
+    DestPort    = 0;
+}
+
+} // namespace Inet
+} // namespace chip

src/inet/IPPacketInfo.h

@@ -0,0 +1,50 @@
+/*
+ *
+ *    Copyright (c) 2020-2021 Project CHIP Authors
+ *    Copyright (c) 2013-2017 Nest Labs, Inc.
+ *
+ *    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 <inet/IPAddress.h>
+#include <inet/InetInterface.h>
+
+namespace chip {
+namespace Inet {
+
+/**
+ * Information about an incoming/outgoing message/connection.
+ *
+ * @warning
+ *     Do not alter the contents of this class without first reading and understanding
+ *     the code/comments in UDPEndPoint::GetPacketInfo().
+ */
+class IPPacketInfo
+{
+public:
+    IPAddress SrcAddress;  /**< The source IPAddress in the packet. */
+    IPAddress DestAddress; /**< The destination IPAddress in the packet. */
+    InterfaceId Interface; /**< The interface identifier for the connection. */
+    uint16_t SrcPort;      /**< The source port in the packet. */
+    uint16_t DestPort;     /**< The destination port in the packet. */
+
+    /**
+     *  Reset the members of the IPPacketInfo object.
+     */
+    void Clear();
+};
+
+} // namespace Inet
+} // namespace chip

src/inet/InetInterface.cpp

@@ -27,10 +27,9 @@
 #define __STDC_LIMIT_MACROS
 #endif
 
-#include "InetInterface.h"
-
-#include "InetLayer.h"
+#include <inet/InetInterface.h>
 
+#include <inet/IPPrefix.h>
 #include <lib/support/CHIPMemString.h>
 #include <lib/support/CodeUtils.h>
 #include <lib/support/DLLUtil.h>