Fix v2 licensing

[fynngodau]

According to latest com.pairip.licensecheck behavior, the third parameter in the licensing v2 call is actually an integer and not a Bundle. I've tested this with current apps that feature v2 licensing, namely org.howwefeel.moodmeter and fr.maif.digital.maifetmoi (note: closes on emulator, but console log from the app indicate that license check is successful).

Regardless, I've verified against https://github.com/e-foundation/lvl-sample that it still works if an empty bundle is passed.

Related: https://gitlab.e.foundation/e/os/backlog/-/issues/3730

Special thanks to @prplwtf.

[mar-v-in]

What is the value of the integer? Does it happen to always be 0?

A Bundle is represented as a typed parcelable object on the parcel, which is [int]0 for null or [int]1 + writeToParcel for non-null values. As such, a fixed value of 0 can be used as a shortcut to represent an always null Bundle.

This also means, that a value of [int]0 should be fully working for the method signature that accepts a Bundle.

So can you please verify the value can be non-zero int?

[fynngodau]

Thanks for the very helpful input @mar-v-in. Indeed my conclusion was nonsensical. The real problem was that we forced the extraParams bundle to be non-null in Kotlin, but it was indeed null (so int = 0 in the parcel). (In my test case with https://github.com/e-foundation/lvl-sample, we pass a non-null empty Bundle, which I never observed in practice…)

[fynngodau]

Some more context on how this bug occurred for those curious or seeking to learn from it:

• I originally wrote the licensing service in Java, and tested it with real apps while cobbling together https://github.com/e-foundation/lvl-sample to ease testing (more feedback, easier to repeat)
• then I migrated to Kotlin, and apparently didn't test with real apps since the test case was passing
• …so ever since then, v2 licensing wasn't actually working
• …but I don't think anybody was affected, and nobody noticed? Since we know that v2 licensing doesn't cause any problem on the client side if you (as microG) receive it without error, but never answer it.