Split Inet::EndPoint into per-implemention files (#11539)

#### Problem

This is a step toward #7715 _Virtualize System and Inet interfaces_.

#### Change overview

Move each `Inet::EndPointBasis` implementation into its own file.
Each inherits from `Inet::EndPointBase`, but transitionally each
implementation is statically named `EndPointBasis`, and initialization
continues to be done in `InitEndPointBasis()` rather than a constructor.

#### Testing

CI; no changes to functionality.

src/inet/BUILD.gn

@@ -49,6 +49,8 @@ buildconfig_header("inet_buildconfig") {
     defines +=
         [ "INET_PLATFORM_CONFIG_INCLUDE=${chip_inet_platform_config_include}" ]
   }
+
+  defines += [ "CHIP_INET_END_POINT_IMPL_CONFIG_FILE=<inet/EndPointBasisImpl${chip_system_config_inet}.h>" ]
 }
 
 source_set("inet_config_header") {
@@ -66,8 +68,8 @@ static_library("inet") {
   output_name = "libInetLayer"
 
   sources = [
-    "EndPointBasis.cpp",
     "EndPointBasis.h",
+    "EndPointBasisImpl${chip_system_config_inet}.h",
     "IANAConstants.h",
     "IPAddress-StringFuncts.cpp",
     "IPAddress.cpp",

src/inet/EndPointBasis.h

@@ -19,29 +19,14 @@
 /**
  *    @file
  *      This file contains the basis class for all the various transport
- *      endpoint classes in the Inet layer, i.e. TCP, UDP, Raw and Tun.
+ *      endpoint classes in the Inet layer, i.e. TCP and UDP.
  */
 
 #pragma once
 
 #include <inet/InetConfig.h>
-
-#include <inet/IPAddress.h>
 #include <lib/support/DLLUtil.h>
 
-#if CHIP_SYSTEM_CONFIG_USE_SOCKETS
-#include <system/SocketEvents.h>
-#endif // CHIP_SYSTEM_CONFIG_USE_SOCKETS
-
-#if CHIP_SYSTEM_CONFIG_USE_NETWORK_FRAMEWORK
-#include <Network/Network.h>
-#endif // CHIP_SYSTEM_CONFIG_USE_NETWORK_FRAMEWORK
-
-#if CHIP_SYSTEM_CONFIG_USE_LWIP
-struct udp_pcb;
-struct tcp_pcb;
-#endif // CHIP_SYSTEM_CONFIG_USE_LWIP
-
 namespace chip {
 namespace Inet {
 
@@ -50,7 +35,7 @@ class InetLayer;
 /**
  * Basis of internet transport endpoint classes.
  */
-class DLL_EXPORT EndPointBasis
+class DLL_EXPORT EndPointBase
 {
 public:
     /**
@@ -73,42 +58,23 @@ class DLL_EXPORT EndPointBasis
     InetLayer * mInetLayer; /**< Pointer to the InetLayer object that owns this object. */
 
 protected:
-    void InitEndPointBasis(InetLayer & aInetLayer, void * aAppState = nullptr);
+    virtual ~EndPointBase() = default;
 
-#if CHIP_SYSTEM_CONFIG_USE_NETWORK_FRAMEWORK
-    nw_parameters_t mParameters;
-    IPAddressType mAddrType; /**< Protocol family, i.e. IPv4 or IPv6. */
-#endif
-
-#if CHIP_SYSTEM_CONFIG_USE_SOCKETS
-    static constexpr int kInvalidSocketFd = -1;
-    int mSocket;                     /**< Encapsulated socket descriptor. */
-    IPAddressType mAddrType;         /**< Protocol family, i.e. IPv4 or IPv6. */
-    System::SocketWatchToken mWatch; /**< Socket event watcher */
-#endif                               // CHIP_SYSTEM_CONFIG_USE_SOCKETS
-
-#if CHIP_SYSTEM_CONFIG_USE_LWIP
-    /** Encapsulated LwIP protocol control block */
-    union
+    void InitEndPointBasis(InetLayer & aInetLayer, void * aAppState = nullptr)
     {
-#if INET_CONFIG_ENABLE_UDP_ENDPOINT
-        udp_pcb * mUDP; /**< User datagram protocol (UDP) control */
-#endif                  // INET_CONFIG_ENABLE_UDP_ENDPOINT
-#if INET_CONFIG_ENABLE_TCP_ENDPOINT
-        tcp_pcb * mTCP; /**< Transmission control protocol (TCP) control */
-#endif                  // INET_CONFIG_ENABLE_TCP_ENDPOINT
-    };
+        AppState   = aAppState;
+        mInetLayer = &aInetLayer;
+        InitEndPointBasisImpl();
+    }
 
-    enum class LwIPEndPointType : uint8_t
-    {
-        Unknown = 0,
-        Raw     = 1,
-        UDP     = 2,
-        UCP     = 3,
-        TCP     = 4
-    } mLwIPEndPointType;
-#endif // CHIP_SYSTEM_CONFIG_USE_LWIP
+    virtual void InitEndPointBasisImpl() = 0;
 };
 
 } // namespace Inet
 } // namespace chip
+
+#ifdef CHIP_INET_END_POINT_IMPL_CONFIG_FILE
+#include CHIP_INET_END_POINT_IMPL_CONFIG_FILE
+#else // CHIP_INET_END_POINT_IMPL_CONFIG_FILE
+#include <inet/EndPointBasisImplSockets.h>
+#endif // CHIP_INET_END_POINT_IMPL_CONFIG_FILE

src/inet/EndPointBasisImplLwIP.h

@@ -0,0 +1,64 @@
+/*
+ *
+ *    Copyright (c) 2020-2021 Project CHIP Authors
+ *    Copyright (c) 2015-2017 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.
+ */
+
+/**
+ *  LwIP implementation of EndPointBase.
+ */
+
+#pragma once
+
+#include <inet/EndPointBasis.h>
+
+#include <inet/IPAddress.h>
+
+struct udp_pcb;
+struct tcp_pcb;
+
+namespace chip {
+namespace Inet {
+
+class DLL_EXPORT EndPointImplLwIP : public EndPointBase
+{
+protected:
+    // EndPointBase overrides
+    void InitEndPointBasisImpl() override { mLwIPEndPointType = LwIPEndPointType::Unknown; }
+
+    /** Encapsulated LwIP protocol control block */
+    union
+    {
+        const void * mVoid; /**< An untyped protocol control buffer reference */
+#if INET_CONFIG_ENABLE_UDP_ENDPOINT
+        udp_pcb * mUDP; /**< User datagram protocol (UDP) control */
+#endif                  // INET_CONFIG_ENABLE_UDP_ENDPOINT
+#if INET_CONFIG_ENABLE_TCP_ENDPOINT
+        tcp_pcb * mTCP; /**< Transmission control protocol (TCP) control */
+#endif                  // INET_CONFIG_ENABLE_TCP_ENDPOINT
+    };
+
+    enum class LwIPEndPointType : uint8_t
+    {
+        Unknown = 0,
+        UDP     = 1,
+        TCP     = 2
+    } mLwIPEndPointType;
+};
+
+using EndPointBasis = EndPointImplLwIP;
+
+} // namespace Inet
+} // namespace chip

src/inet/EndPointBasisImplNetworkFramework.h

@@ -0,0 +1,46 @@
+/*
+ *
+ *    Copyright (c) 2020-2021 Project CHIP Authors
+ *    Copyright (c) 2015-2017 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.
+ */
+
+/**
+ *  Network Framework implementation of EndPointBase.
+ */
+
+#pragma once
+
+#include <inet/EndPointBasis.h>
+
+#include <inet/IPAddress.h>
+
+#include <Network/Network.h>
+
+namespace chip {
+namespace Inet {
+
+class DLL_EXPORT EndPointImplNetworkFramework : public EndPointBase
+{
+protected:
+    void InitEndPointBasisImpl() override {}
+
+    nw_parameters_t mParameters;
+    IPAddressType mAddrType; /**< Protocol family, i.e. IPv4 or IPv6. */
+};
+
+using EndPointBasis = EndPointImplNetworkFramework;
+
+} // namespace Inet
+} // namespace chip

src/inet/EndPointBasisImplSockets.h

@@ -0,0 +1,47 @@
+/*
+ *
+ *    Copyright (c) 2020-2021 Project CHIP Authors
+ *    Copyright (c) 2015-2017 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.
+ */
+
+/**
+ *  Sockets implementation of EndPointBase.
+ */
+
+#pragma once
+
+#include <inet/EndPointBasis.h>
+
+#include <inet/IPAddress.h>
+#include <system/SocketEvents.h>
+
+namespace chip {
+namespace Inet {
+
+class DLL_EXPORT EndPointImplSockets : public EndPointBase
+{
+protected:
+    void InitEndPointBasisImpl() override { mSocket = kInvalidSocketFd; }
+
+    static constexpr int kInvalidSocketFd = -1;
+    int mSocket;                     /**< Encapsulated socket descriptor. */
+    IPAddressType mAddrType;         /**< Protocol family, i.e. IPv4 or IPv6. */
+    System::SocketWatchToken mWatch; /**< Socket event watcher */
+};
+
+using EndPointBasis = EndPointImplSockets;
+
+} // namespace Inet
+} // namespace chip

src/inet/inet.gni

@@ -25,4 +25,11 @@ declare_args() {
 
   # Enable TCP endpoint.
   chip_inet_config_enable_tcp_endpoint = true
+
+  # Inet implementation type.
+  if (chip_system_config_use_lwip) {
+    chip_system_config_inet = "LwIP"
+  } else {
+    chip_system_config_inet = "Sockets"
+  }
 }