session-android/src/org/thoughtcrime/securesms/service/KeyCachingService.java

/**
 * Copyright (C) 2011 Whisper Systems
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package org.thoughtcrime.securesms.service;

import android.app.AlarmManager;
import android.app.Notification;
import android.app.PendingIntent;
import android.app.Service;
import android.content.Intent;
import android.content.SharedPreferences;
import android.os.Binder;
import android.os.IBinder;
import android.os.SystemClock;
import android.preference.PreferenceManager;
import android.util.Log;

import org.thoughtcrime.securesms.ApplicationPreferencesActivity;
import org.thoughtcrime.securesms.ConversationListActivity;
import org.thoughtcrime.securesms.R;
import org.thoughtcrime.securesms.crypto.MasterSecret;

/**
 * Small service that stays running to keep a key cached in memory.
 *
 * @author Moxie Marlinspike
 */

public class KeyCachingService extends Service {

  public static final int    NOTIFICATION_ID    = 1337;
  public static final int    SERVICE_RUNNING_ID = 4141;

  public  static final String KEY_PERMISSION           = "org.thoughtcrime.securesms.ACCESS_SECRETS";
  public  static final String NEW_KEY_EVENT            = "org.thoughtcrime.securesms.service.action.NEW_KEY_EVENT";
  public  static final String PASSPHRASE_EXPIRED_EVENT = "org.thoughtcrime.securesms.service.action.PASSPHRASE_EXPIRED_EVENT";
  public  static final String CLEAR_KEY_ACTION         = "org.thoughtcrime.securesms.service.action.CLEAR_KEY";
  public  static final String ACTIVITY_START_EVENT     = "org.thoughtcrime.securesms.service.action.ACTIVITY_START_EVENT";
  public  static final String ACTIVITY_STOP_EVENT      = "org.thoughtcrime.securesms.service.action.ACTIVITY_STOP_EVENT";
  public  static final String PREFERENCES_NAME         = "SecureSMS-Preferences";


  private PendingIntent pending;
  private int activitiesRunning = 0;
  private final IBinder binder  = new KeyCachingBinder();

  private MasterSecret masterSecret;

  public KeyCachingService() {}

  public synchronized MasterSecret getMasterSecret() {
    return masterSecret;
  }

  public synchronized void setMasterSecret(MasterSecret masterSecret) {
    this.masterSecret = masterSecret;

    foregroundService();
    broadcastNewSecret();
    startTimeoutIfAppropriate();
  }

  @Override
  public void onStart(Intent intent, int startId) {
    if (intent == null) return;

    if (intent.getAction() != null && intent.getAction().equals(CLEAR_KEY_ACTION))
      handleClearKey();
    else if (intent.getAction() != null && intent.getAction().equals(ACTIVITY_START_EVENT))
      handleActivityStarted();
    else if (intent.getAction() != null && intent.getAction().equals(ACTIVITY_STOP_EVENT))
      handleActivityStopped();
    else if (intent.getAction() != null && intent.getAction().equals(PASSPHRASE_EXPIRED_EVENT))
      handlePassphraseExpired();
  }

  @Override
  public void onCreate() {
    pending = PendingIntent.getService(this, 0, new Intent(PASSPHRASE_EXPIRED_EVENT, null, this, KeyCachingService.class), 0);
  }

  @Override
  public void onDestroy() {
    Log.e("kcs", "KCS Is Being Destroyed!");
  }

  private void handleActivityStarted() {
    Log.w("KeyCachingService", "Incrementing activity count...");

    AlarmManager alarmManager = (AlarmManager)this.getSystemService(ALARM_SERVICE);
    alarmManager.cancel(pending);
    activitiesRunning++;
  }

  private void handleActivityStopped() {
    Log.w("KeyCachingService", "Decrementing activity count...");

    activitiesRunning--;
    startTimeoutIfAppropriate();
  }

  private void handleClearKey() {
    this.masterSecret = null;
    stopForeground(true);
  }

  private void handlePassphraseExpired() {
    handleClearKey();
    Intent intent = new Intent(PASSPHRASE_EXPIRED_EVENT);
    intent.setPackage(getApplicationContext().getPackageName());

    sendBroadcast(intent, KEY_PERMISSION);
  }

  private void startTimeoutIfAppropriate() {
    SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(this);
    boolean timeoutEnabled              = sharedPreferences.getBoolean(ApplicationPreferencesActivity.PASSPHRASE_TIMEOUT_PREF, false);

    if ((activitiesRunning == 0) && (this.masterSecret != null) && timeoutEnabled) {
      long timeoutMinutes = sharedPreferences.getInt(ApplicationPreferencesActivity.PASSPHRASE_TIMEOUT_INTERVAL_PREF, 60 * 5);
      long timeoutMillis  = timeoutMinutes * 60 * 1000;

      Log.w("KeyCachingService", "Starting timeout: " + timeoutMillis);

      AlarmManager alarmManager = (AlarmManager)this.getSystemService(ALARM_SERVICE);
      alarmManager.cancel(pending);
      alarmManager.set(AlarmManager.ELAPSED_REALTIME, SystemClock.elapsedRealtime() + timeoutMillis, pending);
    }
  }

  private void foregroundService() {
    Notification notification  = new Notification(R.drawable.icon_cached,
                                                  getString(R.string.textsecure_passphrase_cached),
                                                  System.currentTimeMillis());
    Intent intent              = new Intent(this, ConversationListActivity.class);
    PendingIntent launchIntent = PendingIntent.getActivity(getApplicationContext(), 0, intent, 0);
    notification.setLatestEventInfo(getApplicationContext(), getString(R.string.textsecure_cached),
                                    getString(R.string.textsecure_passphrase_cached), launchIntent);

    stopForeground(true);
    startForeground(SERVICE_RUNNING_ID, notification);
  }

  private void broadcastNewSecret() {
    Log.w("service", "Broadcasting new secret...");
    Intent intent = new Intent(NEW_KEY_EVENT);
    intent.putExtra("master_secret", masterSecret);
    intent.setPackage(getApplicationContext().getPackageName());

    sendBroadcast(intent, KEY_PERMISSION);
  }


  @Override
  public IBinder onBind(Intent arg0) {
    return binder;
  }

  public class KeyCachingBinder extends Binder {
    public KeyCachingService getService() {
      return KeyCachingService.this;
    }
  }
}