IMA shouldOverrideUrlLoading NPEs

[dbrain]

Issue description

We are seeing a lot of NullPointerException's in Firebase coming from IMA in our latest release, containing ExoPlayer 2.12.0 and IMA 3.21.4 (Note: ExoPlayer specifies 3.21.0, so we've bumped it slightly).

GIven it's IMA and obfuscated it's hard to work out exactly what is going wrong from our perspective. It seems like at some point the WebView is triggering a URL load, which is causing IMA to call into components it thinks should not be null, but are at that point.

I'm guessing it's some kind of lifecycle thing, maybe ExoPlayer has detached when this event occurs or hasn't attached yet. Hoping someone who has worked with the IMA code could shed some light / point me in the right direction.

Reproduction steps

I have been so far unable to reproduce this, or find a specific flow making it happen.

Link to test content

Not content specific.

Stacktraces

Note, the actual crashes have repeats of this due to the way WebViews are implemented across devices.

Crash 1

Fatal Exception: java.lang.NullPointerException: Attempt to invoke interface method 'java.lang.Object com.google.ads.interactivemedia.v3.api.StreamRequest.getUserRequestContext()' on a null object reference
       at com.google.ads.interactivemedia.v3.internal.amr.c(IMASDK:3)
       at com.google.ads.interactivemedia.v3.internal.aog.d(IMASDK:66)
       at com.google.ads.interactivemedia.v3.internal.aom.d(IMASDK:5)
       at com.google.ads.interactivemedia.v3.internal.aoj.shouldOverrideUrlLoading(IMASDK:2)
       at android.webkit.WebViewClient.shouldOverrideUrlLoading(WebViewClient.java:77)
       at org.chromium.android_webview.AwContentsClientBridge.shouldOverrideUrlLoading(chromium-Monochrome.aab-stable-428010123:17)
       at android.os.MessageQueue.nativePollOnce(MessageQueue.java)
       at android.os.MessageQueue.next(MessageQueue.java:326)
       at android.os.Looper.loop(Looper.java:165)
       at android.app.ActivityThread.main(ActivityThread.java:6810)
       at java.lang.reflect.Method.invoke(Method.java)
       at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:547)
       at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:873)

Crash 2

Fatal Exception: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String com.google.ads.interactivemedia.v3.internal.and.g()' on a null object reference
       at com.google.ads.interactivemedia.v3.internal.amr.a(IMASDK:2)
       at com.google.ads.interactivemedia.v3.internal.aog.d(IMASDK:71)
       at com.google.ads.interactivemedia.v3.internal.aom.d(IMASDK:5)
       at com.google.ads.interactivemedia.v3.internal.aoj.shouldOverrideUrlLoading(IMASDK:2)
       at android.webkit.WebViewClient.shouldOverrideUrlLoading(WebViewClient.java:77)
       at org.chromium.android_webview.AwContentsClientBridge.shouldOverrideUrlLoading(chromium-Monochrome.aab-stable-428014120:17)
       at android.os.MessageQueue.nativePollOnce(MessageQueue.java)
       at android.os.MessageQueue.next(MessageQueue.java:326)
       at android.os.Looper.loop(Looper.java:183)
       at android.app.ActivityThread.main(ActivityThread.java:7258)
       at java.lang.reflect.Method.invoke(Method.java)
       at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:494)
       at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:975)

Version of ExoPlayer being used

2.12.0 with IMA 3.21.4

Device(s) and version(s) of Android being used

Device and OS independent

[andrewlewis]

The mention of StreamRequest.getUserRequestContext() suggests that the use case is server-side ad insertion/DAI. Could you confirm whether that's expected?

If so I think this needs to be investigated by the IMA SDK team, so you could post a description of the problem here.

[dbrain]

@andrewlewis Sorry, I should have clarified in the description. We do not use DAI, just plain old IMA via VAST/VMAP.

Given the IMA SDK is trying to hit a null StreamRequest, maybe it's some backup flow? Hard to tell with the obfuscated IMA code.

[andrewlewis]

I've asked the IMA SDK team to take a look in [internal: b/177294971] and will plan to keep this issue updated if we learn more. Thanks.

[andrewlewis]

There's a fix for the NullPointerException which will hopefully go into the next IMA SDK release (I'd guess this will be 3.22.1 as it just missed the 3.22.0 release -- here's the repository). Although this will fix the NPE, without details about how the error was triggered, it's hard to say what the root cause could be. With the fix, it's possible that a more informative error will be propagated to allow diagnosing what's going on.