Merge "[KA04] Expose TCP socket keepalive API" am: b099846c86 am: f924dfe504

am: 3e622644b4

Change-Id: I490acd417b3f70ba1dec3bbf9f049088b849c782

core/java/android/net/ConnectivityManager.java

@@ -68,6 +68,7 @@ import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
 import java.net.InetAddress;
 import java.net.InetSocketAddress;
+import java.net.Socket;
 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.List;
@@ -1889,7 +1890,8 @@ public class ConnectivityManager {
      * @param callback A {@link SocketKeepalive.Callback}. Used for notifications about keepalive
      *        changes. Must be extended by applications that use this API.
      *
-     * @return A {@link SocketKeepalive} object, which can be used to control this keepalive object.
+     * @return A {@link SocketKeepalive} object that can be used to control the keepalive on the
+     *         given socket.
      **/
     public SocketKeepalive createSocketKeepalive(@NonNull Network network,
             @NonNull UdpEncapsulationSocket socket,
@@ -1918,6 +1920,8 @@ public class ConnectivityManager {
      * @param callback A {@link SocketKeepalive.Callback}. Used for notifications about keepalive
      *        changes. Must be extended by applications that use this API.
      *
+     * @return A {@link SocketKeepalive} object that can be used to control the keepalive on the
+     *         given socket.
      * @hide
      */
     @SystemApi
@@ -1932,6 +1936,34 @@ public class ConnectivityManager {
                 source, destination, executor, callback);
     }
 
+    /**
+     * Request that keepalives be started on a TCP socket.
+     * The socket must be established.
+     *
+     * @param network The {@link Network} the socket is on.
+     * @param socket The socket that needs to be kept alive.
+     * @param executor The executor on which callback will be invoked. This implementation assumes
+     *                 the provided {@link Executor} runs the callbacks in sequence with no
+     *                 concurrency. Failing this, no guarantee of correctness can be made. It is
+     *                 the responsibility of the caller to ensure the executor provides this
+     *                 guarantee. A simple way of creating such an executor is with the standard
+     *                 tool {@code Executors.newSingleThreadExecutor}.
+     * @param callback A {@link SocketKeepalive.Callback}. Used for notifications about keepalive
+     *        changes. Must be extended by applications that use this API.
+     *
+     * @return A {@link SocketKeepalive} object that can be used to control the keepalive on the
+     *         given socket.
+     * @hide
+     */
+    @SystemApi
+    @RequiresPermission(android.Manifest.permission.PACKET_KEEPALIVE_OFFLOAD)
+    public SocketKeepalive createSocketKeepalive(@NonNull Network network,
+            @NonNull Socket socket,
+            @NonNull Executor executor,
+            @NonNull Callback callback) {
+        return new TcpSocketKeepalive(mService, network, socket, executor, callback);
+    }
+
     /**
      * Ensure that a network route exists to deliver traffic to the specified
      * host via the specified network interface. An attempt to add a route that

core/java/android/net/IConnectivityManager.aidl

@@ -188,6 +188,9 @@ interface IConnectivityManager
             int intervalSeconds, in Messenger messenger, in IBinder binder, String srcAddr,
             String dstAddr);
 
+    void startTcpKeepalive(in Network network, in FileDescriptor fd, int intervalSeconds,
+            in Messenger messenger, in IBinder binder);
+
     void stopKeepalive(in Network network, int slot);
 
     String getCaptivePortalServerUrl();

core/java/android/net/NetworkAgent.java

@@ -178,6 +178,26 @@ public abstract class NetworkAgent extends Handler {
      */
     public static final int EVENT_SOCKET_KEEPALIVE = BASE + 13;
 
+    // TODO: move the above 2 constants down so they are in order once merge conflicts are resolved
+    /**
+     * Sent by the KeepaliveTracker to NetworkAgent to add a packet filter.
+     *
+     * For TCP keepalive offloads, keepalive packets are sent by the firmware. However, because the
+     * remote site will send ACK packets in response to the keepalive packets, the firmware also
+     * needs to be configured to properly filter the ACKs to prevent the system from waking up.
+     * This does not happen with UDP, so this message is TCP-specific.
+     * arg1 = slot number of the keepalive to filter for.
+     * obj = the keepalive packet to send repeatedly.
+     */
+    public static final int CMD_ADD_KEEPALIVE_PACKET_FILTER = BASE + 16;
+
+    /**
+     * Sent by the KeepaliveTracker to NetworkAgent to remove a packet filter. See
+     * {@link #CMD_ADD_KEEPALIVE_PACKET_FILTER}.
+     * arg1 = slot number of the keepalive packet filter to remove.
+     */
+    public static final int CMD_REMOVE_KEEPALIVE_PACKET_FILTER = BASE + 17;
+
     /**
      * Sent by ConnectivityService to inform this network transport of signal strength thresholds
      * that when crossed should trigger a system wakeup and a NetworkCapabilities update.
@@ -329,6 +349,14 @@ public abstract class NetworkAgent extends Handler {
                 preventAutomaticReconnect();
                 break;
             }
+            case CMD_ADD_KEEPALIVE_PACKET_FILTER: {
+                addKeepalivePacketFilter(msg);
+                break;
+            }
+            case CMD_REMOVE_KEEPALIVE_PACKET_FILTER: {
+                removeKeepalivePacketFilter(msg);
+                break;
+            }
         }
     }
 
@@ -477,6 +505,24 @@ public abstract class NetworkAgent extends Handler {
         queueOrSendMessage(EVENT_SOCKET_KEEPALIVE, slot, reason);
     }
 
+    /**
+     * Called by ConnectivityService to add specific packet filter to network hardware to block
+     * ACKs matching the sent keepalive packets. Implementations that support this feature must
+     * override this method.
+     */
+    protected void addKeepalivePacketFilter(Message msg) {
+        onSocketKeepaliveEvent(msg.arg1, SocketKeepalive.ERROR_HARDWARE_UNSUPPORTED);
+    }
+
+    /**
+     * Called by ConnectivityService to remove a packet filter installed with
+     * {@link #addKeepalivePacketFilter(Message)}. Implementations that support this feature
+     * must override this method.
+     */
+    protected void removeKeepalivePacketFilter(Message msg) {
+        onSocketKeepaliveEvent(msg.arg1, SocketKeepalive.ERROR_HARDWARE_UNSUPPORTED);
+    }
+
     /**
      * Called by ConnectivityService to inform this network transport of signal strength thresholds
      * that when crossed should trigger a system wakeup and a NetworkCapabilities update.

core/java/android/net/SocketKeepalive.java

@@ -19,6 +19,7 @@ package android.net;
 import android.annotation.IntDef;
 import android.annotation.IntRange;
 import android.annotation.NonNull;
+import android.annotation.Nullable;
 import android.os.Handler;
 import android.os.HandlerThread;
 import android.os.Looper;
@@ -155,7 +156,7 @@ public abstract class SocketKeepalive implements AutoCloseable {
     @NonNull private final SocketKeepalive.Callback mCallback;
     @NonNull private final Looper mLooper;
     @NonNull final Messenger mMessenger;
-    @NonNull Integer mSlot;
+    @Nullable Integer mSlot;
 
     SocketKeepalive(@NonNull IConnectivityManager service, @NonNull Network network,
             @NonNull Executor executor, @NonNull Callback callback) {

core/java/android/net/TcpSocketKeepalive.java

@@ -0,0 +1,78 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * 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.
+ */
+
+package android.net;
+
+import android.annotation.NonNull;
+import android.os.Binder;
+import android.os.RemoteException;
+import android.util.Log;
+
+import java.io.FileDescriptor;
+import java.net.Socket;
+import java.util.concurrent.Executor;
+
+/** @hide */
+final class TcpSocketKeepalive extends SocketKeepalive {
+
+    private final Socket mSocket;
+
+    TcpSocketKeepalive(@NonNull IConnectivityManager service,
+            @NonNull Network network,
+            @NonNull Socket socket,
+            @NonNull Executor executor,
+            @NonNull Callback callback) {
+        super(service, network, executor, callback);
+        mSocket = socket;
+    }
+
+    /**
+     * Starts keepalives. {@code mSocket} must be a connected TCP socket.
+     *
+     * - The application must not write to or read from the socket after calling this method, until
+     *   onDataReceived, onStopped, or onError are called. If it does, the keepalive will fail
+     *   with {@link #ERROR_SOCKET_NOT_IDLE}, or {@code #ERROR_INVALID_SOCKET} if the socket
+     *   experienced an error (as in poll(2) returned POLLERR); if this happens, the data received
+     *   from the socket may be invalid, and the socket can't be recovered.
+     * - If the socket has data in the send or receive buffer, then this call will fail with
+     *   {@link #ERROR_SOCKET_NOT_IDLE} and can be retried after the data has been processed.
+     *   An app could ensure this by using an application-layer protocol where it can receive
+     *   acknowledgement that it will go into keepalive mode. It could then go into keepalive
+     *   mode after having read the acknowledgement, draining the socket.
+     */
+    @Override
+    void startImpl(int intervalSec) {
+        try {
+            final FileDescriptor fd = mSocket.getFileDescriptor$();
+            mService.startTcpKeepalive(mNetwork, fd, intervalSec, mMessenger, new Binder());
+        } catch (RemoteException e) {
+            Log.e(TAG, "Error starting packet keepalive: ", e);
+            stopLooper();
+        }
+    }
+
+    @Override
+    void stopImpl() {
+        try {
+            if (mSlot != null) {
+                mService.stopKeepalive(mNetwork, mSlot);
+            }
+        } catch (RemoteException e) {
+            Log.e(TAG, "Error stopping packet keepalive: ", e);
+            stopLooper();
+        }
+    }
+}

services/core/java/com/android/server/ConnectivityService.java

@@ -6376,6 +6376,14 @@ public class ConnectivityService extends IConnectivityManager.Stub
                 srcAddr, dstAddr, NattSocketKeepalive.NATT_PORT);
     }
 
+    @Override
+    public void startTcpKeepalive(Network network, FileDescriptor fd, int intervalSeconds,
+            Messenger messenger, IBinder binder) {
+        enforceKeepalivePermission();
+        mKeepaliveTracker.startTcpKeepalive(
+                getNetworkAgentInfoForNetwork(network), fd, intervalSeconds, messenger, binder);
+    }
+
     @Override
     public void stopKeepalive(Network network, int slot) {
         mHandler.sendMessage(mHandler.obtainMessage(

services/core/java/com/android/server/connectivity/KeepaliveTracker.java

@@ -17,6 +17,8 @@
 package com.android.server.connectivity;
 
 import static android.net.NattSocketKeepalive.NATT_PORT;
+import static android.net.NetworkAgent.CMD_ADD_KEEPALIVE_PACKET_FILTER;
+import static android.net.NetworkAgent.CMD_REMOVE_KEEPALIVE_PACKET_FILTER;
 import static android.net.NetworkAgent.CMD_START_SOCKET_KEEPALIVE;
 import static android.net.NetworkAgent.CMD_STOP_SOCKET_KEEPALIVE;
 import static android.net.NetworkAgent.EVENT_SOCKET_KEEPALIVE;
@@ -37,6 +39,9 @@ import android.net.NattKeepalivePacketData;
 import android.net.NetworkAgent;
 import android.net.NetworkUtils;
 import android.net.SocketKeepalive.InvalidPacketException;
+import android.net.SocketKeepalive.InvalidSocketException;
+import android.net.TcpKeepalivePacketData;
+import android.net.TcpKeepalivePacketData.TcpSocketInfo;
 import android.net.util.IpUtils;
 import android.os.Binder;
 import android.os.Handler;
@@ -65,7 +70,7 @@ import java.util.HashMap;
  *
  * Provides methods to stop and start keepalive requests, and keeps track of keepalives across all
  * networks. This class is tightly coupled to ConnectivityService. It is not thread-safe and its
- * methods must be called only from the ConnectivityService handler thread.
+ * handle* methods must be called only from the ConnectivityService handler thread.
  */
 public class KeepaliveTracker {
 
@@ -78,9 +83,12 @@ public class KeepaliveTracker {
     private final HashMap <NetworkAgentInfo, HashMap<Integer, KeepaliveInfo>> mKeepalives =
             new HashMap<> ();
     private final Handler mConnectivityServiceHandler;
+    @NonNull
+    private final TcpKeepaliveController mTcpController;
 
     public KeepaliveTracker(Handler handler) {
         mConnectivityServiceHandler = handler;
+        mTcpController = new TcpKeepaliveController(handler);
     }
 
     /**
@@ -96,20 +104,33 @@ public class KeepaliveTracker {
         private final int mUid;
         private final int mPid;
         private final NetworkAgentInfo mNai;
+        private final int mType;
+        private final FileDescriptor mFd;
 
-        /** Keepalive slot. A small integer that identifies this keepalive among the ones handled
+        public static final int TYPE_NATT = 1;
-          * by this network. */
+        public static final int TYPE_TCP = 2;
+
+        // Keepalive slot. A small integer that identifies this keepalive among the ones handled
+        // by this network.
         private int mSlot = NO_KEEPALIVE;
 
         // Packet data.
         private final KeepalivePacketData mPacket;
         private final int mInterval;
 
-        // Whether the keepalive is started or not.
+        // Whether the keepalive is started or not. The initial state is NOT_STARTED.
-        public boolean isStarted;
+        private static final int NOT_STARTED = 1;
+        private static final int STARTING = 2;
+        private static final int STARTED = 3;
+        private int mStartedState = NOT_STARTED;
 
-        public KeepaliveInfo(Messenger messenger, IBinder binder, NetworkAgentInfo nai,
+        KeepaliveInfo(@NonNull Messenger messenger,
-                KeepalivePacketData packet, int interval) {
+                @NonNull IBinder binder,
+                @NonNull NetworkAgentInfo nai,
+                @NonNull KeepalivePacketData packet,
+                int interval,
+                int type,
+                @NonNull FileDescriptor fd) {
             mMessenger = messenger;
             mBinder = binder;
             mPid = Binder.getCallingPid();
@@ -118,6 +139,8 @@ public class KeepaliveTracker {
             mNai = nai;
             mPacket = packet;
             mInterval = interval;
+            mType = type;
+            mFd = fd;
 
             try {
                 mBinder.linkToDeath(this, 0);
@@ -130,32 +153,40 @@ public class KeepaliveTracker {
             return mNai;
         }
 
+        private String startedStateString(final int state) {
+            switch (state) {
+                case NOT_STARTED : return "NOT_STARTED";
+                case STARTING : return "STARTING";
+                case STARTED : return "STARTED";
+            }
+            throw new IllegalArgumentException("Unknown state");
+        }
+
         public String toString() {
-            return new StringBuffer("KeepaliveInfo [")
+            return "KeepaliveInfo ["
-                    .append(" network=").append(mNai.network)
+                    + " network=" + mNai.network
-                    .append(" isStarted=").append(isStarted)
+                    + " startedState=" + startedStateString(mStartedState)
-                    .append(" ")
+                    + " "
-                    .append(IpUtils.addressAndPortToString(mPacket.srcAddress, mPacket.srcPort))
+                    + IpUtils.addressAndPortToString(mPacket.srcAddress, mPacket.srcPort)
-                    .append("->")
+                    + "->"
-                    .append(IpUtils.addressAndPortToString(mPacket.dstAddress, mPacket.dstPort))
+                    + IpUtils.addressAndPortToString(mPacket.dstAddress, mPacket.dstPort)
-                    .append(" interval=" + mInterval)
+                    + " interval=" + mInterval
-                    .append(" packetData=" + HexDump.toHexString(mPacket.getPacket()))
+                    + " uid=" + mUid + " pid=" + mPid
-                    .append(" uid=").append(mUid).append(" pid=").append(mPid)
+                    + " packetData=" + HexDump.toHexString(mPacket.getPacket())
-                    .append(" ]")
+                    + " ]";
-                    .toString();
         }
 
         /** Sends a message back to the application via its SocketKeepalive.Callback. */
         void notifyMessenger(int slot, int err) {
+            if (DBG) {
+                Log.d(TAG, "notify keepalive " + mSlot + " on " + mNai.network + " for " + err);
+            }
             KeepaliveTracker.this.notifyMessenger(mMessenger, slot, err);
         }
 
         /** Called when the application process is killed. */
         public void binderDied() {
-            // Not called from ConnectivityService handler thread, so send it a message.
+            stop(BINDER_DIED);
-            mConnectivityServiceHandler.obtainMessage(
-                    NetworkAgent.CMD_STOP_SOCKET_KEEPALIVE,
-                    mSlot, BINDER_DIED, mNai.network).sendToTarget();
         }
 
         void unlinkDeathRecipient() {
@@ -202,7 +233,26 @@ public class KeepaliveTracker {
             int error = isValid();
             if (error == SUCCESS) {
                 Log.d(TAG, "Starting keepalive " + mSlot + " on " + mNai.name());
-                mNai.asyncChannel.sendMessage(CMD_START_SOCKET_KEEPALIVE, slot, mInterval, mPacket);
+                switch (mType) {
+                    case TYPE_NATT:
+                        mNai.asyncChannel
+                                .sendMessage(CMD_START_SOCKET_KEEPALIVE, slot, mInterval, mPacket);
+                        break;
+                    case TYPE_TCP:
+                        mTcpController.startSocketMonitor(mFd, this, mSlot);
+                        mNai.asyncChannel
+                                .sendMessage(CMD_ADD_KEEPALIVE_PACKET_FILTER, slot, 0 /* Unused */,
+                                        mPacket);
+                        // TODO: check result from apf and notify of failure as needed.
+                        mNai.asyncChannel
+                                .sendMessage(CMD_START_SOCKET_KEEPALIVE, slot, mInterval, mPacket);
+                        break;
+                    default:
+                        Log.wtf(TAG, "Starting keepalive with unknown type: " + mType);
+                        handleStopKeepalive(mNai, mSlot, error);
+                        return;
+                }
+                mStartedState = STARTING;
             } else {
                 handleStopKeepalive(mNai, mSlot, error);
                 return;
@@ -216,15 +266,27 @@ public class KeepaliveTracker {
                     Log.e(TAG, "Cannot stop unowned keepalive " + mSlot + " on " + mNai.network);
                 }
             }
-            if (isStarted) {
+            if (NOT_STARTED != mStartedState) {
                 Log.d(TAG, "Stopping keepalive " + mSlot + " on " + mNai.name());
-                mNai.asyncChannel.sendMessage(CMD_STOP_SOCKET_KEEPALIVE, mSlot);
+                if (mType == TYPE_NATT) {
+                    mNai.asyncChannel.sendMessage(CMD_STOP_SOCKET_KEEPALIVE, mSlot);
+                } else if (mType == TYPE_TCP) {
+                    mNai.asyncChannel.sendMessage(CMD_STOP_SOCKET_KEEPALIVE, mSlot);
+                    mNai.asyncChannel.sendMessage(CMD_REMOVE_KEEPALIVE_PACKET_FILTER, mSlot);
+                    mTcpController.stopSocketMonitor(mSlot);
+                } else {
+                    Log.wtf(TAG, "Stopping keepalive with unknown type: " + mType);
+                }
             }
             // TODO: at the moment we unconditionally return failure here. In cases where the
             // NetworkAgent is alive, should we ask it to reply, so it can return failure?
             notifyMessenger(mSlot, reason);
             unlinkDeathRecipient();
         }
+
+        void onFileDescriptorInitiatedStop(final int socketKeepaliveReason) {
+            handleStopKeepalive(mNai, mSlot, socketKeepaliveReason);
+        }
     }
 
     void notifyMessenger(Messenger messenger, int slot, int err) {
@@ -328,20 +390,38 @@ public class KeepaliveTracker {
             return;
         }
 
-        if (reason == SUCCESS && !ki.isStarted) {
+        // This can be called in a number of situations :
+        // - startedState is STARTING.
+        //   - reason is SUCCESS => go to STARTED.
+        //   - reason isn't SUCCESS => it's an error starting. Go to NOT_STARTED and stop keepalive.
+        // - startedState is STARTED.
+        //   - reason is SUCCESS => it's a success stopping. Go to NOT_STARTED and stop keepalive.
+        //   - reason isn't SUCCESS => it's an error in exec. Go to NOT_STARTED and stop keepalive.
+        // The control is not supposed to ever come here if the state is NOT_STARTED. This is
+        // because in NOT_STARTED state, the code will switch to STARTING before sending messages
+        // to start, and the only way to NOT_STARTED is this function, through the edges outlined
+        // above : in all cases, keepalive gets stopped and can't restart without going into
+        // STARTING as messages are ordered. This also depends on the hardware processing the
+        // messages in order.
+        // TODO : clarify this code and get rid of mStartedState. Using a StateMachine is an
+        // option.
+        if (reason == SUCCESS && KeepaliveInfo.STARTING == ki.mStartedState) {
             // Keepalive successfully started.
             if (DBG) Log.d(TAG, "Started keepalive " + slot + " on " + nai.name());
-            ki.isStarted = true;
+            ki.mStartedState = KeepaliveInfo.STARTED;
             ki.notifyMessenger(slot, reason);
         } else {
             // Keepalive successfully stopped, or error.
-            ki.isStarted = false;
+            ki.mStartedState = KeepaliveInfo.NOT_STARTED;
             if (reason == SUCCESS) {
+                // The message indicated success stopping : don't call handleStopKeepalive.
                 if (DBG) Log.d(TAG, "Successfully stopped keepalive " + slot + " on " + nai.name());
             } else {
+                // The message indicated some error trying to start or during the course of
+                // keepalive : do call handleStopKeepalive.
+                handleStopKeepalive(nai, slot, reason);
                 if (DBG) Log.d(TAG, "Keepalive " + slot + " on " + nai.name() + " error " + reason);
             }
-            handleStopKeepalive(nai, slot, reason);
         }
     }
 
@@ -379,7 +459,47 @@ public class KeepaliveTracker {
             notifyMessenger(messenger, NO_KEEPALIVE, e.error);
             return;
         }
-        KeepaliveInfo ki = new KeepaliveInfo(messenger, binder, nai, packet, intervalSeconds);
+        KeepaliveInfo ki = new KeepaliveInfo(messenger, binder, nai, packet, intervalSeconds,
+                KeepaliveInfo.TYPE_NATT, null);
+        mConnectivityServiceHandler.obtainMessage(
+                NetworkAgent.CMD_START_SOCKET_KEEPALIVE, ki).sendToTarget();
+    }
+
+    /**
+     * Called by ConnectivityService to start TCP keepalive on a file descriptor.
+     *
+     * In order to offload keepalive for application correctly, sequence number, ack number and
+     * other fields are needed to form the keepalive packet. Thus, this function synchronously
+     * puts the socket into repair mode to get the necessary information. After the socket has been
+     * put into repair mode, the application cannot access the socket until reverted to normal.
+     *
+     * See {@link android.net.SocketKeepalive}.
+     **/
+    public void startTcpKeepalive(@Nullable NetworkAgentInfo nai,
+            @NonNull FileDescriptor fd,
+            int intervalSeconds,
+            @NonNull Messenger messenger,
+            @NonNull IBinder binder) {
+        if (nai == null) {
+            notifyMessenger(messenger, NO_KEEPALIVE, ERROR_INVALID_NETWORK);
+            return;
+        }
+
+        TcpKeepalivePacketData packet = null;
+        try {
+            TcpSocketInfo tsi = TcpKeepaliveController.switchToRepairMode(fd);
+            packet = TcpKeepalivePacketData.tcpKeepalivePacket(tsi);
+        } catch (InvalidPacketException | InvalidSocketException e) {
+            try {
+                TcpKeepaliveController.switchOutOfRepairMode(fd);
+            } catch (ErrnoException e1) {
+                Log.e(TAG, "Couldn't move fd out of repair mode after failure to start keepalive");
+            }
+            notifyMessenger(messenger, NO_KEEPALIVE, e.error);
+            return;
+        }
+        KeepaliveInfo ki = new KeepaliveInfo(messenger, binder, nai, packet, intervalSeconds,
+                KeepaliveInfo.TYPE_TCP, fd);
         Log.d(TAG, "Created keepalive: " + ki.toString());
         mConnectivityServiceHandler.obtainMessage(CMD_START_SOCKET_KEEPALIVE, ki).sendToTarget();
     }

services/core/java/com/android/server/connectivity/TcpKeepaliveController.java

@@ -15,7 +15,6 @@
  */
 package com.android.server.connectivity;
 
-import static android.net.NetworkAgent.EVENT_SOCKET_KEEPALIVE;
 import static android.net.SocketKeepalive.DATA_RECEIVED;
 import static android.net.SocketKeepalive.ERROR_INVALID_SOCKET;
 import static android.net.SocketKeepalive.ERROR_SOCKET_NOT_IDLE;
@@ -31,10 +30,8 @@ import android.net.SocketKeepalive.InvalidSocketException;
 import android.net.TcpKeepalivePacketData.TcpSocketInfo;
 import android.net.TcpRepairWindow;
 import android.os.Handler;
-import android.os.Message;
 import android.os.MessageQueue;
 import android.os.Messenger;
-import android.os.RemoteException;
 import android.system.ErrnoException;
 import android.system.Int32Ref;
 import android.system.Os;
@@ -42,6 +39,7 @@ import android.util.Log;
 import android.util.SparseArray;
 
 import com.android.internal.annotations.GuardedBy;
+import com.android.server.connectivity.KeepaliveTracker.KeepaliveInfo;
 
 import java.io.FileDescriptor;
 import java.net.InetAddress;
@@ -111,7 +109,7 @@ public class TcpKeepaliveController {
      * tcp/ip information.
      */
     // TODO : make this private. It's far too confusing that this gets called from outside
-    // at a time that nobody can understand, but the switch out is in this class only.
+    // at a time that nobody can understand.
     public static TcpSocketInfo switchToRepairMode(FileDescriptor fd)
             throws InvalidSocketException {
         if (DBG) Log.i(TAG, "switchToRepairMode to start tcp keepalive : " + fd);
@@ -199,7 +197,13 @@ public class TcpKeepaliveController {
                 trw.rcvWndScale);
     }
 
-    private static void switchOutOfRepairMode(@NonNull final FileDescriptor fd)
+    /**
+     * Switch the tcp socket out of repair mode.
+     *
+     * @param fd the fd of socket to switch back to normal.
+     */
+    // TODO : make this private.
+    public static void switchOutOfRepairMode(@NonNull final FileDescriptor fd)
             throws ErrnoException {
         Os.setsockoptInt(fd, IPPROTO_TCP, TCP_REPAIR, TCP_REPAIR_OFF);
     }
@@ -212,7 +216,7 @@ public class TcpKeepaliveController {
      * @param slot keepalive slot.
      */
     public void startSocketMonitor(@NonNull final FileDescriptor fd,
-            @NonNull final Messenger messenger, final int slot) {
+            @NonNull final KeepaliveInfo ki, final int slot) {
         synchronized (mListeners) {
             if (null != mListeners.get(slot)) {
                 throw new IllegalArgumentException("This slot is already taken");
@@ -226,31 +230,13 @@ public class TcpKeepaliveController {
                 // This can't be called twice because the queue guarantees that once the listener
                 // is unregistered it can't be called again, even for a message that arrived
                 // before it was unregistered.
-                int result;
+                final int reason;
-                try {
+                if (0 != (events & EVENT_ERROR)) {
-                    // First move the socket out of repair mode.
+                    reason = ERROR_INVALID_SOCKET;
-                    if (DBG) Log.d(TAG, "Moving socket out of repair mode for event : " + readyFd);
+                } else {
-                    switchOutOfRepairMode(readyFd);
+                    reason = DATA_RECEIVED;
-                    result = (0 != (events & EVENT_ERROR)) ? ERROR_INVALID_SOCKET : DATA_RECEIVED;
-                } catch (ErrnoException e) {
-                    // Could not move the socket out of repair mode. Still continue with notifying
-                    // the client
-                    Log.e(TAG, "Cannot switch socket out of repair mode", e);
-                    result = ERROR_INVALID_SOCKET;
-                }
-                // Prepare and send the message to the receiver.
-                final Message message = Message.obtain();
-                message.what = EVENT_SOCKET_KEEPALIVE;
-                message.arg1 = slot;
-                message.arg2 = result;
-                try {
-                    messenger.send(message);
-                } catch (RemoteException e) {
-                    // Remote process died
-                }
-                synchronized (mListeners) {
-                    mListeners.remove(slot);
                 }
+                ki.onFileDescriptorInitiatedStop(reason);
                 // The listener returns the new set of events to listen to. Because 0 means no
                 // event, the listener gets unregistered.
                 return 0;