session-android/src/org/thoughtcrime/securesms/service/SmsListener.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.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.os.Build;
import android.os.Bundle;
import android.provider.Telephony;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.support.annotation.VisibleForTesting;
import android.telephony.SmsMessage;
import android.util.Log;

import org.thoughtcrime.securesms.ApplicationContext;
import org.thoughtcrime.securesms.RegistrationActivity;
import org.thoughtcrime.securesms.jobs.SmsReceiveJob;
import org.thoughtcrime.securesms.util.TextSecurePreferences;
import org.thoughtcrime.securesms.util.Util;

import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class SmsListener extends BroadcastReceiver {

  private static final String SMS_RECEIVED_ACTION  = Telephony.Sms.Intents.SMS_RECEIVED_ACTION;
  private static final String SMS_DELIVERED_ACTION = Telephony.Sms.Intents.SMS_DELIVER_ACTION;

  private static final Pattern CHALLENGE_PATTERN = Pattern.compile(".*Your (Signal|TextSecure) verification code:? ([0-9]{3,4})-([0-9]{3,4}).*", Pattern.DOTALL);

  private boolean isExemption(SmsMessage message, String messageBody) {

    // ignore CLASS0 ("flash") messages
    if (message.getMessageClass() == SmsMessage.MessageClass.CLASS_0)
      return true;

    // ignore OTP messages from Sparebank1 (Norwegian bank)
    if (messageBody.startsWith("Sparebank1://otp?")) {
      return true;
    }

    return
      message.getOriginatingAddress().length() < 7 &&
      (messageBody.toUpperCase().startsWith("//ANDROID:") || // Sprint Visual Voicemail
       messageBody.startsWith("//BREW:")); //BREW stands for “Binary Runtime Environment for Wireless"
  }

  private SmsMessage getSmsMessageFromIntent(Intent intent) {
    Bundle bundle             = intent.getExtras();
    Object[] pdus             = (Object[])bundle.get("pdus");

    if (pdus == null || pdus.length == 0)
      return null;

    return SmsMessage.createFromPdu((byte[])pdus[0]);
  }

  private String getSmsMessageBodyFromIntent(Intent intent) {
    Bundle bundle             = intent.getExtras();
    Object[] pdus             = (Object[])bundle.get("pdus");
    StringBuilder bodyBuilder = new StringBuilder();

    if (pdus == null)
      return null;

    for (Object pdu : pdus)
      bodyBuilder.append(SmsMessage.createFromPdu((byte[])pdu).getDisplayMessageBody());

    return bodyBuilder.toString();
  }

  private boolean isRelevant(Context context, Intent intent) {
    SmsMessage message = getSmsMessageFromIntent(intent);
    String messageBody = getSmsMessageBodyFromIntent(intent);

    if (message == null && messageBody == null)
      return false;

    if (isExemption(message, messageBody))
      return false;

    if (!ApplicationMigrationService.isDatabaseImported(context))
      return false;

    if (isChallenge(context, messageBody))
      return false;

    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT &&
        SMS_RECEIVED_ACTION.equals(intent.getAction()) &&
        Util.isDefaultSmsProvider(context))
    {
      return false;
    }

    if (Build.VERSION.SDK_INT < Build.VERSION_CODES.KITKAT &&
        TextSecurePreferences.isInterceptAllSmsEnabled(context))
    {
      return true;
    }

    return false;
  }

  @VisibleForTesting boolean isChallenge(@NonNull Context context, @Nullable String messageBody) {
    if (messageBody == null)
      return false;

    if (CHALLENGE_PATTERN.matcher(messageBody).matches() &&
        TextSecurePreferences.isVerifying(context))
    {
      return true;
    }

    return false;
  }

  @VisibleForTesting String parseChallenge(String messageBody) {
    Matcher challengeMatcher = CHALLENGE_PATTERN.matcher(messageBody);

    if (!challengeMatcher.matches()) {
      throw new AssertionError("Expression should match.");
    }

    return challengeMatcher.group(2) + challengeMatcher.group(3);
  }

  @Override
  public void onReceive(Context context, Intent intent) {
    Log.w("SMSListener", "Got SMS broadcast...");

    String messageBody = getSmsMessageBodyFromIntent(intent);
    if (SMS_RECEIVED_ACTION.equals(intent.getAction()) && isChallenge(context, messageBody)) {
      Log.w("SmsListener", "Got challenge!");
      Intent challengeIntent = new Intent(RegistrationActivity.CHALLENGE_EVENT);
      challengeIntent.putExtra(RegistrationActivity.CHALLENGE_EXTRA, parseChallenge(messageBody));
      context.sendBroadcast(challengeIntent);

      abortBroadcast();
    } else if ((intent.getAction().equals(SMS_DELIVERED_ACTION)) ||
               (intent.getAction().equals(SMS_RECEIVED_ACTION)) && isRelevant(context, intent))
    {
      Log.w("SmsListener", "Constructing SmsReceiveJob...");
      Object[] pdus           = (Object[]) intent.getExtras().get("pdus");
      int      subscriptionId = intent.getExtras().getInt("subscription", -1);

      ApplicationContext.getInstance(context).getJobManager().add(new SmsReceiveJob(context, pdus, subscriptionId));

      abortBroadcast();
    }
  }
}