Creating a default viewer / receiver for Android email attachments

Question

I'm trying to create a default handler for .p7s/.p7b files in Android.

I figured the best start would be to create a BroadcastReceiver that will capture the intent from the Android email application (or K-9 if that's a need) for opening of certain attachments (filtered by mime type). Specifically I'm trying to handle s/mime email so looking for the "application/x-pkcs7-certificates" and "application/x-pkcs7-certificates" mime types.

Just as a basic test I've been trying something like this:

Manifest.xml

<receiver android:name=".IntentReceiver" android:enabled="true">
     <intent-filter>
            <action android:name="android.intent.action.VIEW" />
            <category android:name="android.intent.category.DEFAULT" />
            <category android:name="android.intent.category.BROWSABLE" />
            <data android:mimeType="application/x-pki-signature"/>
     </intent-filter>
</receiver>

Class file.

public class IntentReceiver extends BroadcastReceiver {
    @Override
    public void onReceive(Context context, Intent intent) {
        Log.d("TEST", "Intent was caught");
        //Do something here
    }
}

I've tried using the following mimeType filters as well (testing signatures first):

application/pkcs7-signature
application/x-pkcs7-signature
application/keychain_access

I can't seem to get the IntentReceiver class to capture the intent no matter what filtering I use though. Am I going about this the wrong way?

Answer 1

I would include all of those MIME types (just use multiple <data> elements).

It may be that the MIME type is not being included in the email, though. I don't know how you are sending the emails, but try sending them to some account where you can examine the full source of the email message. If the MIME types are not included in the message, you are out of luck.

You might also test a link to one of these files in a Web page (where the Web server serves up the MIME type header), to confirm that your basic handling is OK.

Answer 2

FIXED: I tried to simply use a regular activity and add the mimeType filtering into that and BAM! it worked. Seems there must be a discrepancies with the BroadcastReceiver not supporting this type of VIEW intent.

New manifest:

<activity android:name=".PkixReceiver"
          android:label="@string/app_name">
    <intent-filter>
        <category android:name="android.intent.category.DEFAULT" />
        <action android:name="android.intent.action.VIEW" />
        <data android:mimeType="application/x-pkcs7-signature" />
        <data android:mimeType="application/pkcs7-signature" />
        <data android:mimeType="application/keychain_access" /> 
    </intent-filter>
</activity>

And now the activity gets fired when the "open" attachment is clicked, success!