Android. Intercept SMS that match a condition using a Service

Question

My carrier (I live in Venezuela) is constantly sending me SMS, some of it is crap, some of it I care about, I dont really want to download an SMS app from the market since im doing something very specific and simple.

Basic idea: I have a BroadcastReceiver that captures the SMS recived intent, in order to be nice to the OS, I dont do any processing here (I want to be able to build rules as complex as I can think of and not have long running issues, maybe using DB or other Asynchronous tasks that cant be done in a BroadcastReceiver), instead I send the same Bundle to an IntentService that processes the SMS.

This works fine in general, I can stop the broadcast if I want to avoid having the System notice I got an SMS, and the IntentService processes the SMS perfectly.

Issue:

How do I process the SMS in the service and then decide wether or not I wanted the System to notice I got an SMS?

I strongly would like to avoid doing the procesing inside the BroadcastReceiver. (This has important repercussions to what you can do in an onReceive(Context, Intent) implementation: anything that requires asynchronous operation is not available, because you will need to return from the function to handle the asynchronous operation, but at that point the BroadcastReceiver is no longer active and thus the system is free to kill its process before the asynchronous operation completes.)

I had though of processing the SMS, and if didnt match my criteria, I could re-issue the SMS Recive broadcast with an aditional extra in the bundle to check wether or not it had been previously verified. But I cant get this to work.

Code:

public class SmsReceiver extends BroadcastReceiver
{
    @Override
    public void onReceive(Context context, Intent intent) 
    {
        if(!intent.getExtras().getBoolean("previouslyChecked",false)){
            this.abortBroadcast();
            Intent serviceIntent = new Intent(context, SmsRecievedServices.class);
            serviceIntent.putExtras(intent);
            context.startService(serviceIntent);
        }
    }
}

public class SmsRecievedServices extends IntentService {

    public SmsRecievedServices() {
        super("SmsRecievedServices");
    }

    @Override
    protected void onHandleIntent(Intent intent) {
        Bundle bundle = intent.getExtras();     
        if(!smsMatchesCriteria(bundle)){
            Intent intent2 = new Intent("android.provider.Telephony.SMS_RECEIVED");
            bundle.putBoolean("previouslyChecked",true);
            intent2.putExtras(bundle);
            sendOrderedBroadcast(intent2,"android.permission.RECEIVE_SMS");
        }           
    }
}

The broadcast reciever gets the intent and doesnt cancel the broadcast, but the system doesnt pick up on the SMS. Any ideas?

Edit (In response to Blundell's comment):

I thought about the fact that maybe me adding an extra would ruin it, so I tried the following:

public class SmsReceiver extends BroadcastReceiver
{
    @Override
    public void onReceive(Context context, Intent intent) 
    {           
        int randomNum = (int)Math.ceil(Math.random()*100);
        if(randomNum > 20){ 
            this.abortBroadcast();
            Intent serviceIntent = new Intent(context, SmsRecievedServices.class);
            serviceIntent.putExtras(intent);
            context.startService(serviceIntent);
        }
    }
}

public class SmsRecievedServices extends IntentService {

    public SmsRecievedServices() {
        super("SmsRecievedServices");
    }

    @Override
    protected void onHandleIntent(Intent intent) {
        Log.i("SMSManager","Forwarding intent");
    Bundle bundle = intent.getExtras();
    Intent intent2 = new Intent("android.provider.Telephony.SMS_RECEIVED");
    intent2.putExtras(bundle);
    sendOrderedBroadcast(intent2, "android.permission.RECEIVE_SMS");
        }
}

LogCat output is:

02-10 22:06:24.632: I/SMSManager(424): RandomNumber: 74
02-10 22:06:24.673: I/SMSManager(424): Forwarding intent
02-10 22:06:24.683: I/SMSManager(424): RandomNumber: 64
02-10 22:06:24.803: I/SMSManager(424): Forwarding intent
02-10 22:06:24.824: I/SMSManager(424): RandomNumber: 28
02-10 22:06:24.832: I/SMSManager(424): Forwarding intent
02-10 22:06:24.854: I/SMSManager(424): RandomNumber: 14

As you can see, the message was hidden from the system three times, the fourth time im not calling abort broadcast as the randomNumber is lower than 20. The OS does not show a new SMS, neither in inbox or notification bar.

Have you tried `sendOrderedBroadcast()` without your bundled extra to see if the system picks that up. Also I've assumed you've already decomposed an intent you haven't created for SMS to see if it has any extras that you need to add? — Blundell, Feb 10 '12 at 21:35
Edited my question to answer your comment. Im resending the exact same intent I got the first time, so I would have thought when the random condition was met, it would show up as a new SMS. — blindstuff, Feb 10 '12 at 22:11
So the issue at the moment is, your forwarding intent isn't working i.e. no new SMS in notifications? — Blundell, Feb 10 '12 at 23:20
In short yes. But if there is a better approach than aborting the broadcast I would also go that route. — blindstuff, Feb 13 '12 at 03:57
The receiver for the `android.provider.Telephony.SMS_RECEIVED` intent in the messaging app is protected and will only process Intents **sent** by the platform (it drops spoofed Intents). The only way to avoid doing the processing in the broadcast receiver is to add the `android.permission.WRITE_SMS` and write the SMS to the database yourself. Since the SMS / MMS provider is not a published API it may vary between versions and vendors - thus integrating with it will likely *suck*. — Jens, Feb 13 '12 at 14:03
Sad news, I find it hard to believe that trying to do things _the_ _right_ _way_ brings more issues than anything. @Jens, do you have any suggestions as how to approach this issue instead? I´ve seen many apps in the Market that do this? Do they just do the checking in the reciever? — blindstuff, Feb 13 '12 at 14:34
Yes typically processing of the message is done in the receiver. Any time consuming actions (such as listing a lot of contact information) should be solved by a caching mechanism in your application. — Jens, Feb 13 '12 at 14:39
@Jens, post your comments up as an answer so I can accept it. It wasnt what I was hoping for but it makes perfect sense. — blindstuff, Feb 13 '12 at 15:01

score 4 · Accepted Answer · answered Feb 13 '12 at 15:05

The receiver for the android.provider.Telephony.SMS_RECEIVED intent in the messaging application is protected and will only process Intents sent by the platform (it drops spoofed Intents).

The only way to avoid doing the processing in the broadcast receiver is to add the android.permission.WRITE_SMS permission to your application and write the SMS to the database yourself.

Since the SMS / MMS provider is not a published API it may vary between versions and vendors - thus integrating with it will likely suck.

Typically processing of the message should be done in the receiver if you want to be able to cancel it. Any time consuming actions (such as listing a lot of contact information) should be solved by a caching mechanism in your application.

score 0 · Answer 2 · answered Feb 07 '12 at 19:32

0

I was reading about this yesterday when investigating push. Article here points to an API which is available for intercepting SMS (under SMS section). It may help?

http://tokudu.com/2010/how-to-implement-push-notifications-for-android/

answered Feb 07 '12 at 19:32

MartinS

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I know how to intercept the SMS. Your link doesnt really help sorry. Btw, If you want to do push in android I would recomend C2DM: http://stackoverflow.com/questions/4014391/anyone-doing-c2dm-on-android/4014969#4014969 – blindstuff Feb 07 '12 at 19:46
Oh well never mind. I thought the API might help https://labs.ericsson.com/apis/mobile-push/ I settled in C2DM solution thanks. – MartinS Feb 07 '12 at 19:52

Android. Intercept SMS that match a condition using a Service

2 Answers2