What exactly is redirect_uri in Google OAuth2 request for getting authorization code in Mobile App?

[agn-7]

According to the Mobile App Google documentation, there is a parameter named redirect_uri which is not clear to me. For example, in the Web App flow of Google OAuth2, the procedure is some communication between front-end, back-end, and google server. In fact, the backend prepares two endpoints one for redirecting to the google auth page which will be called by the frontend, and another endpoint is /oauth2callback which will be called by the google server as a redirect_uri.

My question is, what's the redirect_uri in the Mobile App flow? Is it the same with my backend /oath2callback or Mobile App flow doesn't need any backend part?

Is the following procedure true? First, you create a web application credentials in google developer console, then use the client_id in both react native as well as backend side, next you create the /oath2callback endpoint in the backend and use it as redirect_uri in the native side?

---

[NOTE]:

Actually, I am going to receive credential stuff from the mobile side including access_token, refresh_token, etc, into the backend and store it into the db and use it for calling google API on the server side.

I also couldn't find rasing an issue in https://cloud.google.com/support/ !

---

[UPDATE]

Here's the flow I've implemented:

[Voronar]

Same discussion is here (https://github.com/openid/AppAuth-Android/issues/784#issuecomment-999560861). But even after reading that I am not sure how to use Android App Link (verified https domain) as redirect_uri. If I set working (tested with Android Studio->Tools->App Link Assistant) https app link as redirect_uri I get redirect_uri_mismatch error.

In my case I have these ingredients:

• debug AppplicationID (com.example.my_app)
• Google Cloud Console credential (Android app type) for the com.example.my_app
• verified domain https://my-mobile-app.com with assetlinks.json
• working App Link https://my-mobile-app.com/oauthcallback (tested in emulator)

I tried (without success) this combination of redirect_uris:

com.my-mobile-app:/oauthcallback:

https://accounts.google.com/o/oauth2/v2/auth?
 redirect_uri=com.my-mobile-app%3A%2Foauthcallback&
 scope=profile&
 response_type=code&
 state=strong_state&
 client_id=client_id

https://my-mobile-app.com/oauthcallback:

https://accounts.google.com/o/oauth2/v2/auth?
 redirect_uri=https%3A%2F%2Fmy-mobile-app.com%2Foauthcallback&
 scope=profile&
 response_type=code&
 state=strong_state&
 client_id=client_id

[Voronar]

https://github.com/openid/AppAuth-Android/blob/master/app/README-Google.md partially helps me, but now I need to figuring out what is the correct redirect_uri_path in my case.

Update1. Maybe this guide is not suitable for App Link case at all.

Update2. Yes, this guide describe API Console Credentials page client_id based OAuth2 redirection scheme and it works in my application. Just some tweaks in AndroidManifest.xml intent filter: <data android:pathPattern="/oauth2redirect" android:scheme="com.googleusercontent.apps.CLIENT_ID_PREFIX"/> and redirect_uri becomes com.googleusercontent.apps.CLIENT_ID_PREFIX. But it would be cool to make App Link redirection scheme working too. Similar approach works for iOS with custom URL scheme registration in iOS project settings.