content: /*
   * Copyright (C) 2014 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.UnsupportedAppUsage;
  import android.content.Context;
  import android.os.Build;
  import android.os.Bundle;
  import android.os.Handler;
  import android.os.Looper;
  import android.os.Message;
  import android.os.Messenger;
  import android.util.Log;
  
  import com.android.internal.util.AsyncChannel;
  import com.android.internal.util.Protocol;
  
  import java.util.ArrayList;
  import java.util.concurrent.atomic.AtomicBoolean;
  
  /**
   * A Utility class for handling for communicating between bearer-specific
   * code and ConnectivityService.
   *
   * A bearer may have more than one NetworkAgent if it can simultaneously
   * support separate networks (IMS / Internet / MMS Apns on cellular, or
   * perhaps connections with different SSID or P2P for Wi-Fi).
   *
   * @hide
   */
  public abstract class NetworkAgent extends Handler {
      // Guaranteed to be valid (not NETID_UNSET), otherwise registerNetworkAgent() would have thrown
      // an exception.
      public final int netId;
  
      private volatile AsyncChannel mAsyncChannel;
      private final String LOG_TAG;
      private static final boolean DBG = true;
      private static final boolean VDBG = false;
      private final Context mContext;
      private final ArrayList<Message>mPreConnectedQueue = new ArrayList<Message>();
      private volatile long mLastBwRefreshTime = 0;
      private static final long BW_REFRESH_MIN_WIN_MS = 500;
      private boolean mPollLceScheduled = false;
      private AtomicBoolean mPollLcePending = new AtomicBoolean(false);
      public final int mFactorySerialNumber;
  
      private static final int BASE = Protocol.BASE_NETWORK_AGENT;
  
      /**
       * Sent by ConnectivityService to the NetworkAgent to inform it of
       * suspected connectivity problems on its network.  The NetworkAgent
       * should take steps to verify and correct connectivity.
       */
      public static final int CMD_SUSPECT_BAD = BASE;
  
      /**
       * Sent by the NetworkAgent (note the EVENT vs CMD prefix) to
       * ConnectivityService to pass the current NetworkInfo (connection state).
       * Sent when the NetworkInfo changes, mainly due to change of state.
       * obj = NetworkInfo
       */
      public static final int EVENT_NETWORK_INFO_CHANGED = BASE + 1;
  
      /**
       * Sent by the NetworkAgent to ConnectivityService to pass the current
       * NetworkCapabilties.
       * obj = NetworkCapabilities
       */
      public static final int EVENT_NETWORK_CAPABILITIES_CHANGED = BASE + 2;
  
      /**
       * Sent by the NetworkAgent to ConnectivityService to pass the current
       * NetworkProperties.
       * obj = NetworkProperties
       */
      public static final int EVENT_NETWORK_PROPERTIES_CHANGED = BASE + 3;
  
      /* centralize place where base network score, and network score scaling, will be
       * stored, so as we can consistently compare apple and oranges, or wifi, ethernet and LTE
       */
      public static final int WIFI_BASE_SCORE = 60;
  
      /**
       * Sent by the NetworkAgent to ConnectivityService to pass the current
       * network score.
       * obj = network score Integer
       */
      public static final int EVENT_NETWORK_SCORE_CHANGED = BASE + 4;
  
      /**
       * Sent by ConnectivityService to the NetworkAgent to inform the agent of the
       * networks status - whether we could use the network or could not, due to
       * either a bad network configuration (no internet link) or captive portal.
       *
       * arg1 = either {@code VALID_NETWORK} or {@code INVALID_NETWORK}
       * obj = Bundle containing map from {@code REDIRECT_URL_KEY} to {@code String}
       *       representing URL that Internet probe was redirect to, if it was redirected,
       *       or mapping to {@code null} otherwise.
       */
      public static final int CMD_REPORT_NETWORK_STATUS = BASE + 7;
  
      public static final int VALID_NETWORK = 1;
      public static final int INVALID_NETWORK = 2;
  
      public static String REDIRECT_URL_KEY = "redirect URL";
  
       /**
       * Sent by the NetworkAgent to ConnectivityService to indicate this network was
       * explicitly selected.  This should be sent before the NetworkInfo is marked
       * CONNECTED so it can be given special treatment at that time.
       *
       * obj = boolean indicating whether to use this network even if unvalidated
       */
      public static final int EVENT_SET_EXPLICITLY_SELECTED = BASE + 8;
  
      /**
       * Sent by ConnectivityService to the NetworkAgent to inform the agent of
       * whether the network should in the future be used even if not validated.
       * This decision is made by the user, but it is the network transport's
       * responsibility to remember it.
       *
       * arg1 = 1 if true, 0 if false
       */
      public static final int CMD_SAVE_ACCEPT_UNVALIDATED = BASE + 9;
  
      /**
       * Sent by ConnectivityService to the NetworkAgent to inform the agent to pull
       * the underlying network connection for updated bandwidth information.
       */
      public static final int CMD_REQUEST_BANDWIDTH_UPDATE = BASE + 10;
  
      /**
       * Sent by ConnectivityService to the NetworkAgent to request that the specified packet be sent
       * periodically on the given interval.
       *
       *   arg1 = the slot number of the keepalive to start
       *   arg2 = interval in seconds
       *   obj = KeepalivePacketData object describing the data to be sent
       *
       * Also used internally by ConnectivityService / KeepaliveTracker, with different semantics.
       */
      public static final int CMD_START_SOCKET_KEEPALIVE = BASE + 11;
  
      /**
       * Requests that the specified keepalive packet be stopped.
       *
       * arg1 = slot number of the keepalive to stop.
       *
       * Also used internally by ConnectivityService / KeepaliveTracker, with different semantics.
       */
      public static final int CMD_STOP_SOCKET_KEEPALIVE = BASE + 12;
  
      /**
       * Sent by the NetworkAgent to ConnectivityService to provide status on a socket keepalive
       * request. This may either be the reply to a CMD_START_SOCKET_KEEPALIVE, or an asynchronous
       * error notification.
       *
       * This is also sent by KeepaliveTracker to the app's {@link SocketKeepalive},
       * so that the app's {@link SocketKeepalive.Callback} methods can be called.
       *
       * arg1 = slot number of the keepalive
       * arg2 = error code
       */
      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.
       *
       *   obj = int[] describing signal strength thresholds.
       */
      public static final int CMD_SET_SIGNAL_STRENGTH_THRESHOLDS = BASE + 14;
  
      /**
       * Sent by ConnectivityService to the NeworkAgent to inform the agent to avoid
       * automatically reconnecting to this network (e.g. via autojoin).  Happens
       * when user selects "No" option on the "Stay connected?" dialog box.
       */
      public static final int CMD_PREVENT_AUTOMATIC_RECONNECT = BASE + 15;
  
      // TODO : remove these two constructors. They are a stopgap measure to help sheperding a number
      // of dependent changes that would conflict throughout the automerger graph. Having these
      // temporarily helps with the process of going through with all these dependent changes across
      // the entire tree.
      public NetworkAgent(Looper looper, Context context, String logTag, NetworkInfo ni,
              NetworkCapabilities nc, LinkProperties lp, int score) {
          this(looper, context, logTag, ni, nc, lp, score, null, NetworkFactory.SerialNumber.NONE);
      }
      public NetworkAgent(Looper looper, Context context, String logTag, NetworkInfo ni,
              NetworkCapabilities nc, LinkProperties lp, int score, NetworkMisc misc) {
          this(looper, context, logTag, ni, nc, lp, score, misc, NetworkFactory.SerialNumber.NONE);
      }
  
      public NetworkAgent(Looper looper, Context context, String logTag, NetworkInfo ni,
              NetworkCapabilities nc, LinkProperties lp, int score, int factorySerialNumber) {
          this(looper, context, logTag, ni, nc, lp, score, null, factorySerialNumber);
      }
  
      public NetworkAgent(Looper looper, Context context, String logTag, NetworkInfo ni,
              NetworkCapabilities nc, LinkProperties lp, int score, NetworkMisc misc,
              int factorySerialNumber) {
          super(looper);
          LOG_TAG = logTag;
          mContext = context;
          mFactorySerialNumber = factorySerialNumber;
          if (ni == null || nc == null || lp == null) {
              throw new IllegalArgumentException();
          }
  
          if (VDBG) log("Registering NetworkAgent");
          ConnectivityManager cm = (ConnectivityManager)mContext.getSystemService(
                  Context.CONNECTIVITY_SERVICE);
          netId = cm.registerNetworkAgent(new Messenger(this), new NetworkInfo(ni),
                  new LinkProperties(lp), new NetworkCapabilities(nc), score, misc,
                  factorySerialNumber);
      }
  
      @Override
      public void handleMessage(Message msg) {
          switch (msg.what) {
              case AsyncChannel.CMD_CHANNEL_FULL_CONNECTION: {
                  if (mAsyncChannel != null) {
                      log("Received new connection while already connected!");
                  } else {
                      if (VDBG) log("NetworkAgent fully connected");
                      AsyncChannel ac = new AsyncChannel();
                      ac.connected(null, this, msg.replyTo);
                      ac.replyToMessage(msg, AsyncChannel.CMD_CHANNEL_FULLY_CONNECTED,
                              AsyncChannel.STATUS_SUCCESSFUL);
                      synchronized (mPreConnectedQueue) {
                          mAsyncChannel = ac;
                          for (Message m : mPreConnectedQueue) {
                              ac.sendMessage(m);
                          }
                          mPreConnectedQueue.clear();
                      }
                  }
                  break;
              }
              case AsyncChannel.CMD_CHANNEL_DISCONNECT: {
                  if (VDBG) log("CMD_CHANNEL_DISCONNECT");
                  if (mAsyncChannel != null) mAsyncChannel.disconnect();
                  break;
              }
              case AsyncChannel.CMD_CHANNEL_DISCONNECTED: {
                  if (DBG) log("NetworkAgent channel lost");
                  // let the client know CS is done with us.
                  unwanted();
                  synchronized (mPreConnectedQueue) {
                      mAsyncChannel = null;
                  }
                  break;
              }
              case CMD_SUSPECT_BAD: {
                  log("Unhandled Message " + msg);
                  break;
              }
              case CMD_REQUEST_BANDWIDTH_UPDATE: {
                  long currentTimeMs = System.currentTimeMillis();
                  if (VDBG) {
                      log("CMD_REQUEST_BANDWIDTH_UPDATE request received.");
                  }
                  if (currentTimeMs >= (mLastBwRefreshTime + BW_REFRESH_MIN_WIN_MS)) {
                      mPollLceScheduled = false;
                      if (mPollLcePending.getAndSet(true) == false) {
                          pollLceData();
                      }
                  } else {
                      // deliver the request at a later time rather than discard it completely.
                      if (!mPollLceScheduled) {
                          long waitTime = mLastBwRefreshTime + BW_REFRESH_MIN_WIN_MS -
                                  currentTimeMs + 1;
                          mPollLceScheduled = sendEmptyMessageDelayed(
                                  CMD_REQUEST_BANDWIDTH_UPDATE, waitTime);
                      }
                  }
                  break;
              }
              case CMD_REPORT_NETWORK_STATUS: {
                  String redirectUrl = ((Bundle)msg.obj).getString(REDIRECT_URL_KEY);
                  if (VDBG) {
                      log("CMD_REPORT_NETWORK_STATUS(" +
                              (msg.arg1 == VALID_NETWORK ? "VALID, " : "INVALID, ") + redirectUrl);
                  }
                  networkStatus(msg.arg1, redirectUrl);
                  break;
              }
              case CMD_SAVE_ACCEPT_UNVALIDATED: {
                  saveAcceptUnvalidated(msg.arg1 != 0);
                  break;
              }
              case CMD_START_SOCKET_KEEPALIVE: {
                  startSocketKeepalive(msg);
                  break;
              }
              case CMD_STOP_SOCKET_KEEPALIVE: {
                  stopSocketKeepalive(msg);
                  break;
              }
  
              case CMD_SET_SIGNAL_STRENGTH_THRESHOLDS: {
                  ArrayList<Integer> thresholds =
                          ((Bundle) msg.obj).getIntegerArrayList("thresholds");
                  // TODO: Change signal strength thresholds API to use an ArrayList<Integer>
                  // rather than convert to int[].
                  int[] intThresholds = new int[(thresholds != null) ? thresholds.size() : 0];
                  for (int i = 0; i < intThresholds.length; i++) {
                      intThresholds[i] = thresholds.get(i);
                  }
                  setSignalStrengthThresholds(intThresholds);
                  break;
              }
              case CMD_PREVENT_AUTOMATIC_RECONNECT: {
                  preventAutomaticReconnect();
                  break;
              }
              case CMD_ADD_KEEPALIVE_PACKET_FILTER: {
                  addKeepalivePacketFilter(msg);
                  break;
              }
              case CMD_REMOVE_KEEPALIVE_PACKET_FILTER: {
                  removeKeepalivePacketFilter(msg);
                  break;
              }
          }
      }
  
      private void queueOrSendMessage(int what, Object obj) {
          queueOrSendMessage(what, 0, 0, obj);
      }
  
      private void queueOrSendMessage(int what, int arg1, int arg2) {
          queueOrSendMessage(what, arg1, arg2, null);
      }
  
      private void queueOrSendMessage(int what, int arg1, int arg2, Object obj) {
          Message msg = Message.obtain();
          msg.what = what;
          msg.arg1 = arg1;
          msg.arg2 = arg2;
          msg.obj = obj;
          queueOrSendMessage(msg);
      }
  
      private void queueOrSendMessage(Message msg) {
          synchronized (mPreConnectedQueue) {
              if (mAsyncChannel != null) {
                  mAsyncChannel.sendMessage(msg);
              } else {
                  mPreConnectedQueue.add(msg);
              }
          }
      }
  
      /**
       * Called by the bearer code when it has new LinkProperties data.
       */
      public void sendLinkProperties(LinkProperties linkProperties) {
          queueOrSendMessage(EVENT_NETWORK_PROPERTIES_CHANGED, new LinkProperties(linkProperties));
      }
  
      /**
       * Called by the bearer code when it has new NetworkInfo data.
       */
      @UnsupportedAppUsage(maxTargetSdk = Build.VERSION_CODES.P, trackingBug = 115609023)
      public void sendNetworkInfo(NetworkInfo networkInfo) {
          queueOrSendMessage(EVENT_NETWORK_INFO_CHANGED, new NetworkInfo(networkInfo));
      }
  
      /**
       * Called by the bearer code when it has new NetworkCapabilities data.
       */
      public void sendNetworkCapabilities(NetworkCapabilities networkCapabilities) {
          mPollLcePending.set(false);
          mLastBwRefreshTime = System.currentTimeMillis();
          queueOrSendMessage(EVENT_NETWORK_CAPABILITIES_CHANGED,
                  new NetworkCapabilities(networkCapabilities));
      }
  
      /**
       * Called by the bearer code when it has a new score for this network.
       */
      public void sendNetworkScore(int score) {
          if (score < 0) {
              throw new IllegalArgumentException("Score must be >= 0");
          }
          queueOrSendMessage(EVENT_NETWORK_SCORE_CHANGED,  score, 0);
      }
  
      /**
       * Called by the bearer to indicate this network was manually selected by the user.
       * This should be called before the NetworkInfo is marked CONNECTED so that this
       * Network can be given special treatment at that time. If {@code acceptUnvalidated} is
       * {@code true}, then the system will switch to this network. If it is {@code false} and the
       * network cannot be validated, the system will ask the user whether to switch to this network.
       * If the user confirms and selects "don't ask again", then the system will call
       * {@link #saveAcceptUnvalidated} to persist the user's choice. Thus, if the transport ever
       * calls this method with {@code acceptUnvalidated} set to {@code false}, it must also implement
       * {@link #saveAcceptUnvalidated} to respect the user's choice.
       */
      public void explicitlySelected(boolean acceptUnvalidated) {
          explicitlySelected(true /* explicitlySelected */, acceptUnvalidated);
      }
  
      /**
       * Called by the bearer to indicate this network was manually selected by the user.
       * This should be called before the NetworkInfo is marked CONNECTED so that this
       * Network can be given special treatment at that time. If {@code acceptUnvalidated} is
       * {@code true}, then the system will switch to this network. If it is {@code false} and the
       * network cannot be validated, the system will ask the user whether to switch to this network.
       * If the user confirms and selects "don't ask again", then the system will call
       * {@link #saveAcceptUnvalidated} to persist the user's choice. Thus, if the transport ever
       * calls this method with {@code acceptUnvalidated} set to {@code false}, it must also implement
       * {@link #saveAcceptUnvalidated} to respect the user's choice.
       */
      public void explicitlySelected(boolean explicitlySelected, boolean acceptUnvalidated) {
          queueOrSendMessage(EVENT_SET_EXPLICITLY_SELECTED,
                  explicitlySelected ? 1 : 0,
                  acceptUnvalidated ? 1 : 0);
      }
  
      /**
       * Called when ConnectivityService has indicated they no longer want this network.
       * The parent factory should (previously) have received indication of the change
       * as well, either canceling NetworkRequests or altering their score such that this
       * network won't be immediately requested again.
       */
      abstract protected void unwanted();
  
      /**
       * Called when ConnectivityService request a bandwidth update. The parent factory
       * shall try to overwrite this method and produce a bandwidth update if capable.
       */
      protected void pollLceData() {
      }
  
      /**
       * Called when the system determines the usefulness of this network.
       *
       * Networks claiming internet connectivity will have their internet
       * connectivity verified.
       *
       * Currently there are two possible values:
       * {@code VALID_NETWORK} if the system is happy with the connection,
       * {@code INVALID_NETWORK} if the system is not happy.
       * TODO - add indications of captive portal-ness and related success/failure,
       * ie, CAPTIVE_SUCCESS_NETWORK, CAPTIVE_NETWORK for successful login and detection
       *
       * This may be called multiple times as the network status changes and may
       * generate false negatives if we lose ip connectivity before the link is torn down.
       *
       * @param status one of {@code VALID_NETWORK} or {@code INVALID_NETWORK}.
       * @param redirectUrl If the Internet probe was redirected, this is the destination it was
       *         redirected to, otherwise {@code null}.
       */
      protected void networkStatus(int status, String redirectUrl) {
      }
  
      /**
       * Called when the user asks to remember the choice to use this network even if unvalidated.
       * The transport is responsible for remembering the choice, and the next time the user connects
       * to the network, should explicitlySelected with {@code acceptUnvalidated} set to {@code true}.
       * This method will only be called if {@link #explicitlySelected} was called with
       * {@code acceptUnvalidated} set to {@code false}.
       */
      protected void saveAcceptUnvalidated(boolean accept) {
      }
  
      /**
       * Requests that the network hardware send the specified packet at the specified interval.
       */
      protected void startSocketKeepalive(Message msg) {
          onSocketKeepaliveEvent(msg.arg1, SocketKeepalive.ERROR_UNSUPPORTED);
      }
  
      /**
       * Requests that the network hardware send the specified packet at the specified interval.
       */
      protected void stopSocketKeepalive(Message msg) {
          onSocketKeepaliveEvent(msg.arg1, SocketKeepalive.ERROR_UNSUPPORTED);
      }
  
      /**
       * Called by the network when a socket keepalive event occurs.
       */
      public void onSocketKeepaliveEvent(int slot, int reason) {
          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) {
      }
  
      /**
       * 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) {
      }
  
      /**
       * Called by ConnectivityService to inform this network transport of signal strength thresholds
       * that when crossed should trigger a system wakeup and a NetworkCapabilities update.
       */
      protected void setSignalStrengthThresholds(int[] thresholds) {
      }
  
      /**
       * Called when the user asks to not stay connected to this network because it was found to not
       * provide Internet access.  Usually followed by call to {@code unwanted}.  The transport is
       * responsible for making sure the device does not automatically reconnect to the same network
       * after the {@code unwanted} call.
       */
      protected void preventAutomaticReconnect() {
      }
  
      protected void log(String s) {
          Log.d(LOG_TAG, "NetworkAgent: " + s);
      }
  }
  