feat: handle play store developer notifications

[pavelbrm]

Summary

This PR introduces handling for Google Play Store Developer Notifications aka Android Webhooks. This functionality has been assumed to be implemented and working, but it was neither implemented properly, nor worked.

The new code is extensively covered with tests, unlike what was there before, which could be said to have not had test coverage at all (the original version prior to https://github.com/brave-intl/bat-go/pull/2318 and https://github.com/brave-intl/bat-go/pull/2360).

Also, this PR supersedes https://github.com/brave-intl/bat-go/pull/2341.

Main Changes

Developer notifications are received in the existing endpoint and are handled in a way similar to how App Store Server Notifications are handled:

• A received message must be authenticated. That is, as per configuration, the messages sent to the endpoint will be signed by the service account. Google client library provides the necessary tooling for properly validating received messages. Authentication includes:
  • validating the token (library code);
  • checking the issuer;
  • checking the email in Claims.
• After authentication, the message is parsed.
• During processing, it's determined whether the notification should result in a renewal, cancellation or skipped entirely:
  • Notification types and formats are described here.
  • Only Subscription and Voided Purchase notifications are considered for processing;
  • One Time Product and Test notifications are skipped;
  • a Subscription notification can result in renewal or cancellation;
  • a Voided Purchase notification can result in cancellation;
  • irrelevant Subscription (based on the notification type) or Voided Purchase (based on the product type) notifications are skipped;
  • As a matter of extra protection from messing up with the existing data, and in case GCP sends us old notifications (due to the fact that for some reason notifications have already been configured by somebody in Play Console, but not in Cloud), there is a temporary measure – any notifications issued before 2024-06-01 (i.e. 1 June 2024) will be skipped.
• If a notification is chosen for processing, its purchase token is used to identify the linked order.
• Based on the notification effect (renew or cancel), the found order is either renewed or canceled;
  • to process renewal, a fresh copy of the corresponding subscription is fetched from Google Play Store;
  • the expiry time is set as the expiry date on the order;
  • to process cancellation, no extra information is necessary.
• SKUs does its best to respond with a successful response code:
  • for Order Not Found errors and similar, there is no point in retrying – a notification might come when the user has not yet linked, etc.

Other Changes

A lot of the old garbage code has been purged, and it feels good.

Type of Change

• [x] Product feature
• [x] Bug fix
• [x] Performance improvement
• [x] Refactor
• [ ] Other

Tested Environments

• [ ] Development
• [ ] Staging
• [ ] Production

Before Requesting Review

• [x] Does your code build cleanly without any errors or warnings?
• [ ] Have you used auto closing keywords?
• [x] Have you added tests for new functionality?
• [ ] Have validated query efficiency for new database queries?
• [ ] Have documented new functionality in README or in comments?
• [ ] Have you squashed all intermediate commits?
• [x] Is there a clear title that explains what the PR does?
• [x] Have you used intuitive function, variable and other naming?
• [ ] Have you requested security and/or privacy review if needed
• [ ] Have you performed a self review of this PR?

Manual Test Plan

[github-actions[bot]]

The security team is monitoring all repositories for certain keywords. This PR includes the word(s) "authentication" and so security team members have been added as reviewers to take a look.
No need to request a full security review at this stage, the security team will take a look shortly and either clear the label or request more information/changes.
Notifications have already been sent, but if this is blocking your merge feel free to reach out directly to the security team on Slack so that we can expedite this check.

[pavelbrm]

The security team is monitoring all repositories for certain keywords. This PR includes the word(s) "authentication" and so security team members have been added as reviewers to take a look. No need to request a full security review at this stage, the security team will take a look shortly and either clear the label or request more information/changes. Notifications have already been sent, but if this is blocking your merge feel free to reach out directly to the security team on Slack so that we can expedite this check.

This PR is already under a security review, robot.

[github-actions[bot]]

[puLL-Merge] - brave-intl/bat-go@2560

Description

This PR makes several changes related to handling Play Store notifications for subscriptions in the skus service:

1. Adds new types and methods for parsing and processing Play Store notifications
2. Removes the HandleAndroidWebhook function and related types
3. Adds a new handleWebhookPlayStore function to process Play Store notifications
4. Refactors the gcpPushNotificationValidator to gpsNtfAuthenticator for authenticating Play Store notifications
5. Updates error handling and logging when processing notifications
6. Adds tests for the new Play Store notification processing logic

The motivation for these changes seems to be to improve the handling of Play Store subscription notifications in the skus service.

Changes

### Changes - `services/go.mod`: - Removes the `golang.org/x/crypto` dependency from `require` and moves it to `require` with an `// indirect` comment - `services/skus/appstore.go`: - Adds `shouldCancelOrderIOS` function and related `appStoreTransaction` type to determine if an iOS subscription should be canceled based on the notification payload - `services/skus/appstore_test.go`: - Adds tests for the new `shouldCancelOrderIOS` function - `services/skus/controllers.go`: - Replaces `HandleAndroidWebhook` with a new `handleWebhookPlayStore` function to process Play Store notifications - Refactors `gcpValidator` to `gpsAuth` of type `gpsMessageAuthenticator` - Updates error handling when processing notifications - `services/skus/controllers_noint_test.go`: - Adds a test for `handleReceiptErr` - `services/skus/controllers_pvt_test.go`: - Removes tests for the removed `gcpPushNotificationValidator` type - `services/skus/controllers_test.go`: - Removes the `TestAndroidWebhook` test - Removes `mockVendorReceiptValidator` and `mockGcpRequestValidator` types - `services/skus/input.go`: - Removes `AndroidNotification`, `AndroidNotificationMessage` and related types - `services/skus/model/model.go`: - Adds a new `ErrInvalidVendor` error - `services/skus/playstore.go`: - Adds new types and methods for parsing and processing Play Store notifications - `services/skus/playstore_test.go`: - Adds tests for the new Play Store notification processing logic - `services/skus/receipt.go`: - Removes `dumpTransport` type - Adds `fetchSubPlayStore` method to `vendorReceiptValidator` interface - `services/skus/receipt_test.go`: - Updates tests to use the new error variables from `playstore.go` - `services/skus/service.go`: - Replaces `gcpRequestValidator` with `gpsMessageAuthenticator` in `Service` struct - Adds `processPlayStoreNotification` and `processPlayStoreNotificationTx` methods to handle Play Store notifications - Removes `verifyDeveloperNotification` method - Updates `validateReceipt` to return the new `ErrInvalidVendor` error for unsupported vendors - Removes `shouldCancelOrderIOS` and related `appStoreTransaction` type (moved to `appstore.go`) - `services/skus/service_nonint_test.go`: - Adds tests for the new `processPlayStoreNotificationTx` method - Removes tests for the removed `shouldCancelOrderIOS` function

Security Hotspots

No major security hotspots were identified in this change. The updates primarily focus on refactoring and improving the handling of Play Store notifications for subscriptions.