[1] Inet: Use constructors for Inet EndPoints

#### Problem

`Inet::TCPEndPoint` and `Inet::UDPEndPoint` historically could not use
constructors because of `System::ObjectPool` limitations.

Incidentally renamed `mAppState` for consistency (it had been in
`System::Object` prior to project-chip#11428).

This is a step toward project-chip#7715 _Virtualize System and Inet interfaces_,
split off to reduce the complexity of an upcoming PR.

#### Change overview

Convert from `Init()` to constructors. Transitionally, the constructors
still call a per-implementation function `InitImpl()`.

#### Testing

CI; no changes to functionality.

src/inet/EndPointBasis.h

@@ -38,36 +38,18 @@ class InetLayer;
 class DLL_EXPORT EndPointBase
 {
 public:
-    /**
-     *  Returns a reference to the Inet layer object that owns this basis object.
-     */
-    InetLayer & Layer() const { return *mInetLayer; }
+    EndPointBase(InetLayer & aInetLayer, void * aAppState = nullptr) : mAppState(aAppState), mInetLayer(aInetLayer) {}
+    virtual ~EndPointBase() = default;
 
     /**
-     *  Returns \c true if the basis object was obtained by the specified Inet layer instance.
-     *
-     *  @note
-     *      Does not check whether the object is actually obtained by the system layer instance associated with the Inet layer
-     *      instance. It merely tests whether \c aInetLayer is the Inet layer instance that was provided to \c InitInetLayerBasis.
+     *  Returns a reference to the Inet layer object that owns this basis object.
      */
-    bool IsCreatedByInetLayer(const InetLayer & aInetLayer) const { return mInetLayer == &aInetLayer; }
+    InetLayer & Layer() const { return mInetLayer; }
 
-    void * AppState;
+    void * mAppState;
 
 private:
-    InetLayer * mInetLayer; /**< Pointer to the InetLayer object that owns this object. */
-
-protected:
-    virtual ~EndPointBase() = default;
-
-    void InitEndPointBasis(InetLayer & aInetLayer, void * aAppState = nullptr)
-    {
-        AppState   = aAppState;
-        mInetLayer = &aInetLayer;
-        InitEndPointBasisImpl();
-    }
-
-    virtual void InitEndPointBasisImpl() = 0;
+    InetLayer & mInetLayer; /**< InetLayer object that owns this object. */
 };
 
 } // namespace Inet

src/inet/EndPointBasisImplLwIP.h

@@ -35,8 +35,9 @@ namespace Inet {
 class DLL_EXPORT EndPointImplLwIP : public EndPointBase
 {
 protected:
-    // EndPointBase overrides
-    void InitEndPointBasisImpl() override { mLwIPEndPointType = LwIPEndPointType::Unknown; }
+    EndPointImplLwIP(InetLayer & inetLayer, void * appState = nullptr) :
+        EndPointBase(inetLayer, appState), mLwIPEndPointType(LwIPEndPointType::Unknown)
+    {}
 
     /** Encapsulated LwIP protocol control block */
     union

src/inet/EndPointBasisImplNetworkFramework.h

@@ -34,7 +34,7 @@ namespace Inet {
 class DLL_EXPORT EndPointImplNetworkFramework : public EndPointBase
 {
 protected:
-    void InitEndPointBasisImpl() override {}
+    EndPointImplNetworkFramework(InetLayer & inetLayer, void * appState = nullptr) : EndPointBase(inetLayer, appState) {}
 
     nw_parameters_t mParameters;
     IPAddressType mAddrType; /**< Protocol family, i.e. IPv4 or IPv6. */

src/inet/EndPointBasisImplSockets.h

@@ -33,7 +33,9 @@ namespace Inet {
 class DLL_EXPORT EndPointImplSockets : public EndPointBase
 {
 protected:
-    void InitEndPointBasisImpl() override { mSocket = kInvalidSocketFd; }
+    EndPointImplSockets(InetLayer & inetLayer, void * appState = nullptr) :
+        EndPointBase(inetLayer, appState), mSocket(kInvalidSocketFd)
+    {}
 
     static constexpr int kInvalidSocketFd = -1;
     int mSocket;                     /**< Encapsulated socket descriptor. */

src/inet/InetLayer.cpp

@@ -250,7 +250,7 @@ CHIP_ERROR InetLayer::Shutdown()
 #if INET_CONFIG_ENABLE_TCP_ENDPOINT
     // Abort all TCP endpoints owned by this instance.
     TCPEndPoint::sPool.ForEachActiveObject([&](TCPEndPoint * lEndPoint) {
-        if ((lEndPoint != nullptr) && lEndPoint->IsCreatedByInetLayer(*this))
+        if ((lEndPoint != nullptr) && &lEndPoint->Layer() == this)
         {
             lEndPoint->Abort();
         }
@@ -261,7 +261,7 @@ CHIP_ERROR InetLayer::Shutdown()
 #if INET_CONFIG_ENABLE_UDP_ENDPOINT
     // Close all UDP endpoints owned by this instance.
     UDPEndPoint::sPool.ForEachActiveObject([&](UDPEndPoint * lEndPoint) {
-        if ((lEndPoint != nullptr) && lEndPoint->IsCreatedByInetLayer(*this))
+        if ((lEndPoint != nullptr) && &lEndPoint->Layer() == this)
         {
             lEndPoint->Close();
         }
@@ -429,14 +429,13 @@ CHIP_ERROR InetLayer::NewTCPEndPoint(TCPEndPoint ** retEndPoint)
 
     VerifyOrReturnError(mLayerState.IsInitialized(), CHIP_ERROR_INCORRECT_STATE);
 
-    *retEndPoint = TCPEndPoint::sPool.CreateObject();
+    *retEndPoint = TCPEndPoint::sPool.CreateObject(*this);
     if (*retEndPoint == nullptr)
     {
         ChipLogError(Inet, "%s endpoint pool FULL", "TCP");
         return CHIP_ERROR_ENDPOINT_POOL_FULL;
     }
 
-    (*retEndPoint)->Init(this);
     SYSTEM_STATS_INCREMENT(chip::System::Stats::kInetLayer_NumTCPEps);
 
     return CHIP_NO_ERROR;
@@ -469,14 +468,13 @@ CHIP_ERROR InetLayer::NewUDPEndPoint(UDPEndPoint ** retEndPoint)
 
     VerifyOrReturnError(mLayerState.IsInitialized(), CHIP_ERROR_INCORRECT_STATE);
 
-    *retEndPoint = UDPEndPoint::sPool.CreateObject();
+    *retEndPoint = UDPEndPoint::sPool.CreateObject(*this);
     if (*retEndPoint == nullptr)
     {
         ChipLogError(Inet, "%s endpoint pool FULL", "UDP");
         return CHIP_ERROR_ENDPOINT_POOL_FULL;
     }
 
-    (*retEndPoint)->Init(this);
     SYSTEM_STATS_INCREMENT(chip::System::Stats::kInetLayer_NumUDPEps);
 
     return CHIP_NO_ERROR;
@@ -558,7 +556,7 @@ void InetLayer::HandleTCPInactivityTimer(chip::System::Layer * aSystemLayer, voi
     bool lTimerRequired    = lInetLayer.IsIdleTimerRunning();
 
     TCPEndPoint::sPool.ForEachActiveObject([&](TCPEndPoint * lEndPoint) {
-        if (!lEndPoint->IsCreatedByInetLayer(lInetLayer))
+        if (&lEndPoint->Layer() != &lInetLayer)
             return true;
         if (!lEndPoint->IsConnected())
             return true;

src/inet/TCPEndPoint.cpp

@@ -2594,35 +2594,6 @@ bool TCPEndPoint::IsConnected(State state)
         state == State::kClosing;
 }
 
-void TCPEndPoint::Init(InetLayer * inetLayer)
-{
-    InitEndPointBasis(*inetLayer);
-
-    mReceiveEnabled = true;
-
-    // Initialize to zero for using system defaults.
-    mConnectTimeoutMsecs = 0;
-
-#if INET_CONFIG_OVERRIDE_SYSTEM_TCP_USER_TIMEOUT
-    mUserTimeoutMillis = INET_CONFIG_DEFAULT_TCP_USER_TIMEOUT_MSEC;
-
-    mUserTimeoutTimerRunning = false;
-
-#if INET_CONFIG_ENABLE_TCP_SEND_IDLE_CALLBACKS
-    mIsTCPSendIdle = true;
-
-    mTCPSendQueuePollPeriodMillis = INET_CONFIG_TCP_SEND_QUEUE_POLL_INTERVAL_MSEC;
-
-    mTCPSendQueueRemainingPollCount = MaxTCPSendQueuePolls();
-
-    OnTCPSendIdleChanged = NULL;
-#endif // INET_CONFIG_ENABLE_TCP_SEND_IDLE_CALLBACKS
-
-#endif // INET_CONFIG_OVERRIDE_SYSTEM_TCP_USER_TIMEOUT
-
-    InitImpl();
-}
-
 CHIP_ERROR TCPEndPoint::DriveSending()
 {
     CHIP_ERROR err = DriveSendingImpl();

src/inet/TCPEndPoint.h

@@ -74,7 +74,23 @@ class DLL_EXPORT TCPEndPoint : public EndPointBasis, public ReferenceCounted<TCP
     friend class TCPTest;
 
 public:
-    TCPEndPoint() = default;
+    TCPEndPoint(InetLayer & inetLayer, void * appState = nullptr) :
+        EndPointBasis(inetLayer, appState), mState(State::kReady), mReceiveEnabled(true),
+        mConnectTimeoutMsecs(0) // Initialize to zero for using system defaults.
+#if INET_CONFIG_OVERRIDE_SYSTEM_TCP_USER_TIMEOUT
+        ,
+        mUserTimeoutMillis(INET_CONFIG_DEFAULT_TCP_USER_TIMEOUT_MSEC), mUserTimeoutTimerRunning(false)
+#if INET_CONFIG_ENABLE_TCP_SEND_IDLE_CALLBACKS
+        ,
+        mIsTCPSendIdle(true), mTCPSendQueuePollPeriodMillis(INET_CONFIG_TCP_SEND_QUEUE_POLL_INTERVAL_MSEC),
+        mTCPSendQueueRemainingPollCount(
+            MaxTCPSendQueuePolls(INET_CONFIG_DEFAULT_TCP_USER_TIMEOUT_MSEC, INET_CONFIG_TCP_SEND_QUEUE_POLL_INTERVAL_MSEC)),
+        OnTCPSendIdleChanged(nullptr)
+#endif // INET_CONFIG_ENABLE_TCP_SEND_IDLE_CALLBACKS
+#endif // INET_CONFIG_OVERRIDE_SYSTEM_TCP_USER_TIMEOUT
+    {
+        InitImpl();
+    }
 
     /**
      * @brief   Bind the endpoint to an interface IP address.
@@ -644,13 +660,14 @@ class DLL_EXPORT TCPEndPoint : public EndPointBasis, public ReferenceCounted<TCP
     void ScheduleNextTCPUserTimeoutPoll(uint32_t aTimeOut);
 
 #if INET_CONFIG_ENABLE_TCP_SEND_IDLE_CALLBACKS
-    uint16_t MaxTCPSendQueuePolls(void)
+    static constexpr uint16_t MaxTCPSendQueuePolls(uint16_t userTimeout, uint16_t pollPeriod)
     {
         // If the UserTimeout is configured less than or equal to the poll interval,
         // return 1 to poll at least once instead of returning zero and timing out
         // immediately.
-        return (mUserTimeoutMillis > mTCPSendQueuePollPeriodMillis) ? (mUserTimeoutMillis / mTCPSendQueuePollPeriodMillis) : 1;
+        return (userTimeout > pollPeriod) ? (userTimeout / pollPeriod) : 1;
     }
+    uint16_t MaxTCPSendQueuePolls(void) { return MaxTCPSendQueuePolls(mUserTimeoutMillis, mTCPSendQueuePollPeriodMillis); }
 #endif // INET_CONFIG_ENABLE_TCP_SEND_IDLE_CALLBACKS
 
 #if CHIP_SYSTEM_CONFIG_USE_SOCKETS
@@ -666,7 +683,6 @@ class DLL_EXPORT TCPEndPoint : public EndPointBasis, public ReferenceCounted<TCP
 
     TCPEndPoint(const TCPEndPoint &) = delete;
 
-    void Init(InetLayer * inetLayer);
     CHIP_ERROR DriveSending();
     void DriveReceiving();
     void HandleConnectComplete(CHIP_ERROR err);

src/inet/UDPEndPoint.cpp

@@ -1988,7 +1988,7 @@ CHIP_ERROR UDPEndPoint::Listen(OnMessageReceivedFunct onMessageReceived, OnRecei
 
     OnMessageReceived = onMessageReceived;
     OnReceiveError    = onReceiveError;
-    AppState          = appState;
+    mAppState         = appState;
 
     ReturnErrorOnFailure(ListenImpl());
 
@@ -2028,12 +2028,6 @@ void UDPEndPoint::Close()
     }
 }
 
-void UDPEndPoint::Init(InetLayer * inetLayer)
-{
-    InitEndPointBasis(*inetLayer);
-    InitImpl();
-}
-
 CHIP_ERROR UDPEndPoint::JoinMulticastGroup(InterfaceId aInterfaceId, const IPAddress & aAddress)
 {
     CHIP_ERROR lRetval = CHIP_ERROR_NOT_IMPLEMENTED;

src/inet/UDPEndPoint.h

@@ -63,7 +63,7 @@ class UDPEndPointDeletor
 class DLL_EXPORT UDPEndPoint : public EndPointBasis, public ReferenceCounted<UDPEndPoint, UDPEndPointDeletor>
 {
 public:
-    UDPEndPoint() = default;
+    UDPEndPoint(InetLayer & inetLayer, void * appState = nullptr) : EndPointBasis(inetLayer, appState) { InitImpl(); }
 
     UDPEndPoint(const UDPEndPoint &) = delete;
     UDPEndPoint(UDPEndPoint &&)      = delete;
@@ -262,8 +262,6 @@ class DLL_EXPORT UDPEndPoint : public EndPointBasis, public ReferenceCounted<UDP
 private:
     friend class InetLayer;
 
-    void Init(InetLayer * inetLayer);
-
     /**
      * Basic dynamic state of the underlying endpoint.
      *

src/lib/dnssd/minimal_mdns/Server.cpp

@@ -343,7 +343,7 @@ CHIP_ERROR ServerBase::BroadcastSend(chip::System::PacketBufferHandle && data, u
 void ServerBase::OnUdpPacketReceived(chip::Inet::UDPEndPoint * endPoint, chip::System::PacketBufferHandle && buffer,
                                      const chip::Inet::IPPacketInfo * info)
 {
-    ServerBase * srv = static_cast<ServerBase *>(endPoint->AppState);
+    ServerBase * srv = static_cast<ServerBase *>(endPoint->mAppState);
     if (!srv->mDelegate)
     {
         return;

src/transport/raw/TCP.cpp

@@ -98,7 +98,7 @@ CHIP_ERROR TCPBase::Init(TcpListenParameters & params)
     err = mListenSocket->Listen(kListenBacklogSize);
     SuccessOrExit(err);
 
-    mListenSocket->AppState             = reinterpret_cast<void *>(this);
+    mListenSocket->mAppState            = reinterpret_cast<void *>(this);
     mListenSocket->OnDataReceived       = OnTcpReceive;
     mListenSocket->OnConnectComplete    = OnConnectionComplete;
     mListenSocket->OnConnectionClosed   = OnConnectionClosed;
@@ -254,7 +254,7 @@ CHIP_ERROR TCPBase::SendAfterConnect(const PeerAddress & addr, System::PacketBuf
 #endif
     SuccessOrExit(err);
 
-    endPoint->AppState             = reinterpret_cast<void *>(this);
+    endPoint->mAppState            = reinterpret_cast<void *>(this);
     endPoint->OnDataReceived       = OnTcpReceive;
     endPoint->OnConnectComplete    = OnConnectionComplete;
     endPoint->OnConnectionClosed   = OnConnectionClosed;
@@ -364,7 +364,7 @@ CHIP_ERROR TCPBase::OnTcpReceive(Inet::TCPEndPoint * endPoint, System::PacketBuf
     endPoint->GetInterfaceId(&interfaceId);
     PeerAddress peerAddress = PeerAddress::TCP(ipAddress, port, interfaceId);
 
-    TCPBase * tcp  = reinterpret_cast<TCPBase *>(endPoint->AppState);
+    TCPBase * tcp  = reinterpret_cast<TCPBase *>(endPoint->mAppState);
     CHIP_ERROR err = tcp->ProcessReceivedBuffer(endPoint, peerAddress, std::move(buffer));
 
     if (err != CHIP_NO_ERROR)
@@ -380,7 +380,7 @@ void TCPBase::OnConnectionComplete(Inet::TCPEndPoint * endPoint, CHIP_ERROR inet
 {
     CHIP_ERROR err          = CHIP_NO_ERROR;
     bool foundPendingPacket = false;
-    TCPBase * tcp           = reinterpret_cast<TCPBase *>(endPoint->AppState);
+    TCPBase * tcp           = reinterpret_cast<TCPBase *>(endPoint->mAppState);
     Inet::IPAddress ipAddress;
     uint16_t port;
     Inet::InterfaceId interfaceId;
@@ -452,7 +452,7 @@ void TCPBase::OnConnectionComplete(Inet::TCPEndPoint * endPoint, CHIP_ERROR inet
 
 void TCPBase::OnConnectionClosed(Inet::TCPEndPoint * endPoint, CHIP_ERROR err)
 {
-    TCPBase * tcp = reinterpret_cast<TCPBase *>(endPoint->AppState);
+    TCPBase * tcp = reinterpret_cast<TCPBase *>(endPoint->mAppState);
 
     ChipLogProgress(Inet, "Connection closed.");
 
@@ -470,7 +470,7 @@ void TCPBase::OnConnectionClosed(Inet::TCPEndPoint * endPoint, CHIP_ERROR err)
 void TCPBase::OnConnectionReceived(Inet::TCPEndPoint * listenEndPoint, Inet::TCPEndPoint * endPoint,
                                    const Inet::IPAddress & peerAddress, uint16_t peerPort)
 {
-    TCPBase * tcp = reinterpret_cast<TCPBase *>(listenEndPoint->AppState);
+    TCPBase * tcp = reinterpret_cast<TCPBase *>(listenEndPoint->mAppState);
 
     if (tcp->mUsedEndPointCount < tcp->mActiveConnectionsSize)
     {
@@ -484,7 +484,7 @@ void TCPBase::OnConnectionReceived(Inet::TCPEndPoint * listenEndPoint, Inet::TCP
             }
         }
 
-        endPoint->AppState             = listenEndPoint->AppState;
+        endPoint->mAppState            = listenEndPoint->mAppState;
         endPoint->OnDataReceived       = OnTcpReceive;
         endPoint->OnConnectComplete    = OnConnectionComplete;
         endPoint->OnConnectionClosed   = OnConnectionClosed;
@@ -531,7 +531,7 @@ void TCPBase::Disconnect(const PeerAddress & address)
 
 void TCPBase::OnPeerClosed(Inet::TCPEndPoint * endPoint)
 {
-    TCPBase * tcp = reinterpret_cast<TCPBase *>(endPoint->AppState);
+    TCPBase * tcp = reinterpret_cast<TCPBase *>(endPoint->mAppState);
 
     for (size_t i = 0; i < tcp->mActiveConnectionsSize; i++)
     {

src/transport/raw/UDP.cpp

@@ -114,7 +114,7 @@ CHIP_ERROR UDP::SendMessage(const Transport::PeerAddress & address, System::Pack
 void UDP::OnUdpReceive(Inet::UDPEndPoint * endPoint, System::PacketBufferHandle && buffer, const Inet::IPPacketInfo * pktInfo)
 {
     CHIP_ERROR err          = CHIP_NO_ERROR;
-    UDP * udp               = reinterpret_cast<UDP *>(endPoint->AppState);
+    UDP * udp               = reinterpret_cast<UDP *>(endPoint->mAppState);
     PeerAddress peerAddress = PeerAddress::UDP(pktInfo->SrcAddress, pktInfo->SrcPort, pktInfo->Interface);
 
     udp->HandleMessageReceived(peerAddress, std::move(buffer));