content: /*
   * Copyright (C) 2016 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 com.android.server.connectivity;
  
  import android.app.PendingIntent;
  import android.content.ComponentName;
  import android.content.Context;
  import android.content.Intent;
  import android.net.NetworkCapabilities;
  import android.os.SystemClock;
  import android.os.UserHandle;
  import android.text.TextUtils;
  import android.text.format.DateUtils;
  import android.util.Log;
  import android.util.SparseArray;
  import android.util.SparseIntArray;
  import android.util.SparseBooleanArray;
  import java.util.Arrays;
  import java.util.HashMap;
  
  import com.android.internal.R;
  import com.android.internal.annotations.VisibleForTesting;
  import com.android.internal.util.MessageUtils;
  import com.android.server.connectivity.NetworkNotificationManager;
  import com.android.server.connectivity.NetworkNotificationManager.NotificationType;
  
  import static android.net.ConnectivityManager.NETID_UNSET;
  
  /**
   * Class that monitors default network linger events and possibly notifies the user of network
   * switches.
   *
   * This class is not thread-safe and all its methods must be called on the ConnectivityService
   * handler thread.
   */
  public class LingerMonitor {
  
      private static final boolean DBG = true;
      private static final boolean VDBG = false;
      private static final String TAG = LingerMonitor.class.getSimpleName();
  
      public static final int DEFAULT_NOTIFICATION_DAILY_LIMIT = 3;
      public static final long DEFAULT_NOTIFICATION_RATE_LIMIT_MILLIS = DateUtils.MINUTE_IN_MILLIS;
  
      private static final HashMap<String, Integer> TRANSPORT_NAMES = makeTransportToNameMap();
      @VisibleForTesting
      public static final Intent CELLULAR_SETTINGS = new Intent().setComponent(new ComponentName(
              "com.android.settings", "com.android.settings.Settings$DataUsageSummaryActivity"));
  
      @VisibleForTesting
      public static final int NOTIFY_TYPE_NONE         = 0;
      public static final int NOTIFY_TYPE_NOTIFICATION = 1;
      public static final int NOTIFY_TYPE_TOAST        = 2;
  
      private static SparseArray<String> sNotifyTypeNames = MessageUtils.findMessageNames(
              new Class[] { LingerMonitor.class }, new String[]{ "NOTIFY_TYPE_" });
  
      private final Context mContext;
      private final NetworkNotificationManager mNotifier;
      private final int mDailyLimit;
      private final long mRateLimitMillis;
  
      private long mFirstNotificationMillis;
      private long mLastNotificationMillis;
      private int mNotificationCounter;
  
      /** Current notifications. Maps the netId we switched away from to the netId we switched to. */
      private final SparseIntArray mNotifications = new SparseIntArray();
  
      /** Whether we ever notified that we switched away from a particular network. */
      private final SparseBooleanArray mEverNotified = new SparseBooleanArray();
  
      public LingerMonitor(Context context, NetworkNotificationManager notifier,
              int dailyLimit, long rateLimitMillis) {
          mContext = context;
          mNotifier = notifier;
          mDailyLimit = dailyLimit;
          mRateLimitMillis = rateLimitMillis;
          // Ensure that (now - mLastNotificationMillis) >= rateLimitMillis at first
          mLastNotificationMillis = -rateLimitMillis;
      }
  
      private static HashMap<String, Integer> makeTransportToNameMap() {
          SparseArray<String> numberToName = MessageUtils.findMessageNames(
              new Class[] { NetworkCapabilities.class }, new String[]{ "TRANSPORT_" });
          HashMap<String, Integer> nameToNumber = new HashMap<>();
          for (int i = 0; i < numberToName.size(); i++) {
              // MessageUtils will fail to initialize if there are duplicate constant values, so there
              // are no duplicates here.
              nameToNumber.put(numberToName.valueAt(i), numberToName.keyAt(i));
          }
          return nameToNumber;
      }
  
      private static boolean hasTransport(NetworkAgentInfo nai, int transport) {
          return nai.networkCapabilities.hasTransport(transport);
      }
  
      private int getNotificationSource(NetworkAgentInfo toNai) {
          for (int i = 0; i < mNotifications.size(); i++) {
              if (mNotifications.valueAt(i) == toNai.network.netId) {
                  return mNotifications.keyAt(i);
              }
          }
          return NETID_UNSET;
      }
  
      private boolean everNotified(NetworkAgentInfo nai) {
          return mEverNotified.get(nai.network.netId, false);
      }
  
      @VisibleForTesting
      public boolean isNotificationEnabled(NetworkAgentInfo fromNai, NetworkAgentInfo toNai) {
          // TODO: Evaluate moving to CarrierConfigManager.
          String[] notifySwitches =
                  mContext.getResources().getStringArray(R.array.config_networkNotifySwitches);
  
          if (VDBG) {
              Log.d(TAG, "Notify on network switches: " + Arrays.toString(notifySwitches));
          }
  
          for (String notifySwitch : notifySwitches) {
              if (TextUtils.isEmpty(notifySwitch)) continue;
              String[] transports = notifySwitch.split("-", 2);
              if (transports.length != 2) {
                  Log.e(TAG, "Invalid network switch notification configuration: " + notifySwitch);
                  continue;
              }
              int fromTransport = TRANSPORT_NAMES.get("TRANSPORT_" + transports[0]);
              int toTransport = TRANSPORT_NAMES.get("TRANSPORT_" + transports[1]);
              if (hasTransport(fromNai, fromTransport) && hasTransport(toNai, toTransport)) {
                  return true;
              }
          }
  
          return false;
      }
  
      private void showNotification(NetworkAgentInfo fromNai, NetworkAgentInfo toNai) {
          mNotifier.showNotification(fromNai.network.netId, NotificationType.NETWORK_SWITCH,
                  fromNai, toNai, createNotificationIntent(), true);
      }
  
      @VisibleForTesting
      protected PendingIntent createNotificationIntent() {
          return PendingIntent.getActivityAsUser(mContext, 0, CELLULAR_SETTINGS,
                  PendingIntent.FLAG_CANCEL_CURRENT, null, UserHandle.CURRENT);
      }
  
      // Removes any notification that was put up as a result of switching to nai.
      private void maybeStopNotifying(NetworkAgentInfo nai) {
          int fromNetId = getNotificationSource(nai);
          if (fromNetId != NETID_UNSET) {
              mNotifications.delete(fromNetId);
              mNotifier.clearNotification(fromNetId);
              // Toasts can't be deleted.
          }
      }
  
      // Notify the user of a network switch using a notification or a toast.
      private void notify(NetworkAgentInfo fromNai, NetworkAgentInfo toNai, boolean forceToast) {
          int notifyType =
                  mContext.getResources().getInteger(R.integer.config_networkNotifySwitchType);
          if (notifyType == NOTIFY_TYPE_NOTIFICATION && forceToast) {
              notifyType = NOTIFY_TYPE_TOAST;
          }
  
          if (VDBG) {
              Log.d(TAG, "Notify type: " + sNotifyTypeNames.get(notifyType, "" + notifyType));
          }
  
          switch (notifyType) {
              case NOTIFY_TYPE_NONE:
                  return;
              case NOTIFY_TYPE_NOTIFICATION:
                  showNotification(fromNai, toNai);
                  break;
              case NOTIFY_TYPE_TOAST:
                  mNotifier.showToast(fromNai, toNai);
                  break;
              default:
                  Log.e(TAG, "Unknown notify type " + notifyType);
                  return;
          }
  
          if (DBG) {
              Log.d(TAG, "Notifying switch from=" + fromNai.name() + " to=" + toNai.name() +
                      " type=" + sNotifyTypeNames.get(notifyType, "unknown(" + notifyType + ")"));
          }
  
          mNotifications.put(fromNai.network.netId, toNai.network.netId);
          mEverNotified.put(fromNai.network.netId, true);
      }
  
      // The default network changed from fromNai to toNai due to a change in score.
      public void noteLingerDefaultNetwork(NetworkAgentInfo fromNai, NetworkAgentInfo toNai) {
          if (VDBG) {
              Log.d(TAG, "noteLingerDefaultNetwork from=" + fromNai.name() +
                      " everValidated=" + fromNai.everValidated +
                      " lastValidated=" + fromNai.lastValidated +
                      " to=" + toNai.name());
          }
  
          // If we are currently notifying the user because the device switched to fromNai, now that
          // we are switching away from it we should remove the notification. This includes the case
          // where we switch back to toNai because its score improved again (e.g., because it regained
          // Internet access).
          maybeStopNotifying(fromNai);
  
          // If this network never validated, don't notify. Otherwise, we could do things like:
          //
          // 1. Unvalidated wifi connects.
          // 2. Unvalidated mobile data connects.
          // 3. Cell validates, and we show a notification.
          // or:
          // 1. User connects to wireless printer.
          // 2. User turns on cellular data.
          // 3. We show a notification.
          if (!fromNai.everValidated) return;
  
          // If this network is a captive portal, don't notify. This cannot happen on initial connect
          // to a captive portal, because the everValidated check above will fail. However, it can
          // happen if the captive portal reasserts itself (e.g., because its timeout fires). In that
          // case, as soon as the captive portal reasserts itself, we'll show a sign-in notification.
          // We don't want to overwrite that notification with this one; the user has already been
          // notified, and of the two, the captive portal notification is the more useful one because
          // it allows the user to sign in to the captive portal. In this case, display a toast
          // in addition to the captive portal notification.
          //
          // Note that if the network we switch to is already up when the captive portal reappears,
          // this won't work because NetworkMonitor tells ConnectivityService that the network is
          // unvalidated (causing a switch) before asking it to show the sign in notification. In this
          // case, the toast won't show and we'll only display the sign in notification. This is the
          // best we can do at this time.
          boolean forceToast = fromNai.networkCapabilities.hasCapability(
                  NetworkCapabilities.NET_CAPABILITY_CAPTIVE_PORTAL);
  
          // Only show the notification once, in order to avoid irritating the user every time.
          // TODO: should we do this?
          if (everNotified(fromNai)) {
              if (VDBG) {
                  Log.d(TAG, "Not notifying handover from " + fromNai.name() + ", already notified");
              }
              return;
          }
  
          // Only show the notification if we switched away because a network became unvalidated, not
          // because its score changed.
          // TODO: instead of just skipping notification, keep a note of it, and show it if it becomes
          // unvalidated.
          if (fromNai.lastValidated) return;
  
          if (!isNotificationEnabled(fromNai, toNai)) return;
  
          final long now = SystemClock.elapsedRealtime();
          if (isRateLimited(now) || isAboveDailyLimit(now)) return;
  
          notify(fromNai, toNai, forceToast);
      }
  
      public void noteDisconnect(NetworkAgentInfo nai) {
          mNotifications.delete(nai.network.netId);
          mEverNotified.delete(nai.network.netId);
          maybeStopNotifying(nai);
          // No need to cancel notifications on nai: NetworkMonitor does that on disconnect.
      }
  
      private boolean isRateLimited(long now) {
          final long millisSinceLast = now - mLastNotificationMillis;
          if (millisSinceLast < mRateLimitMillis) {
              return true;
          }
          mLastNotificationMillis = now;
          return false;
      }
  
      private boolean isAboveDailyLimit(long now) {
          if (mFirstNotificationMillis == 0) {
              mFirstNotificationMillis = now;
          }
          final long millisSinceFirst = now - mFirstNotificationMillis;
          if (millisSinceFirst > DateUtils.DAY_IN_MILLIS) {
              mNotificationCounter = 0;
              mFirstNotificationMillis = 0;
          }
          if (mNotificationCounter >= mDailyLimit) {
              return true;
          }
          mNotificationCounter++;
          return false;
      }
  }
  