TrackingCategory.RECOMMENDED does not block ads as expected

[mcomella]

I tried applying TrackingCategory.RECOMMENDED in FFTV but ads still appeared:

trackingCategories = arrayOf(TrackingCategory.RECOMMENDED)

(This is how the default values for TrackingProtectionPolicy.select define it)

I switched to adding these categories manually and it worked fine:

trackingCategories = arrayOf(TrackingCategory.AD, TrackingCategory.ANALYTICS, TrackingCategory.SOCIAL)

Looking at the code, these values are being added together:

android-components/components/concept/engine/src/main/java/mozilla/components/concept/engine/EngineSession.kt

Line 179 in 1c65263

RECOMMENDED(AD.id + ANALYTICS.id + SOCIAL.id + TEST.id),

However, these values look like they're supposed to be bit-packed because other values use bit-shift operators: I think they should be using and instead of +.

┆Issue is synchronized with this Jira Task

[mcomella]

Note: I tested on rottentomatoes.com which shows a banner ad at the top.

CC @pocmo This seems important because tracking protection may be broken in our apps.

[mcomella]

I set it up using and but that doesn't seem to work either: I'll leave this to the professionals.

[pocmo]

CC @Amejia481

[Amejia481]

On it!

[Amejia481]

I tried applying TrackingCategory.RECOMMENDED in FFTV but ads still appeared:

@mcomella I believe tracking protection does not block ads, it blocks scripts/cookies/content from trackers depending on which policy you choose. ( I have to confirm). For blocking ads we need an Adblocker.

Ads not showing maybe a side effect in some cases, as they may depend on the scripts/cookies/content that we are blocking.

---

If you want to confirm the categories, that you want are getting apply you can test verifying
the session.trackersBlocked property that reports a list of trackers blocked on a site. When a site finishes loading it should contain trackers that belong to the categories that you applied (As long as the site has these trackers categories on it)

If we take https://rottentomatoes.com/ as a guinea pig and apply TrackingProtectionPolicy.recommended() (AD,ANALYTICS and SOCIAL), when the page finishes loading we are going to get reported that:

session.trackersBlocked.trackingCategories
contains TrackingCategory.AD,TrackingCategory.ANALYTICS and TrackingCategory.ANALYTICS.

A tracker may contain multiple categories, you can use the snippet below to not show duplicates:

var categoriesBlocked = mutableSetOf<EngineSession.TrackingProtectionPolicy.TrackingCategory>()

session.trackersBlocked.forEach{
    categoriesBlocked.addAll(it.trackingCategories.toSet())
}

If we use the same site but just applying AD:

TrackingProtectionPolicy.select(arrayOf(TrackingProtectionPolicy.TrackingCategory.AD))

When the page finishes loading session.trackersBlocked.trackingCategories is going to contain
only TrackingProtectionPolicy.TrackingCategory.AD (I apply the snipped above to avoid duplicates)

The same could be seen if we apply just
TrackingProtectionPolicy.select(arrayOf(TrackingProtectionPolicy.TrackingCategory.ANALYTICS))

When the page finishes loading session.trackersBlocked.trackingCategories is going to contain
only TrackingProtectionPolicy.TrackingCategory.ANALYTICS (I apply the snipped above to avoid duplicates)

[pocmo]

@Amejia481 Did you verify that this is still the case for WebView (browser-engine-system) too?

[Amejia481]

Checking!

[Amejia481]

Issue discovered, working on a patch!
Thanks @mcomella for reporting it!

[Amejia481]

trackingCategories = arrayOf(TrackingCategory.AD, TrackingCategory.ANALYTICS, TrackingCategory.SOCIAL)

@mcomella As you described above, until the fix lands you have to add the categories manually, sorry for that!

[mcomella]

I believe tracking protection does not block ads, it blocks scripts/cookies/content from trackers depending on which policy you choose.

Sorry I was not explicit about SystemWebView (FFTV is still on it) and about ^: a side effect of TP is that it blocks ads and the ad I usually use for testing wasn't blocked. I probably should have been clearer. :)

[Amejia481]

I really appreciate you were very diligent double checking after the API refactoring. I'm covering with more tests to avoid similar issues in the future :), Sorry for the inconvenience, that this may cause you!

[mcomella]

I really appreciate you were very diligent double checking after the API refactoring. I'm covering with more tests to avoid similar issues in the future :)

And thanks for writing those tests. :)