Bug Description

As reported in #3007 when using the GoDaddy CDN Site Kit is incorrectly detecting an Ad Blocker, resulting in non reporting of AdSense dashboards and the inability to connect the module.

A temporarily workaround for impacted users is to deactivate this CDN configuration from their GoDaddy control panel.

Screenshots

Impacted Users

In addition to the helpful insights @rafapontederino provided there have been 3 additional reports in the support forms, details below, all occurring in the past week:

• Report 1 unresolved (SH info provided)
• Report 2 unresolved (SH info provided)
• Report 3 unresolved (SH info provided)
• Report 4 unresolved
• Report 5 - Unresolved (SH info provided)

Additional Context

• No common plugins between impacted users
• All sites fully secure with redirection in place
• No additional hosting level additions applied by original user who reported this
• Unreproducible in support so far on GoDaddy hosting
• Incognito doesn't allow setup to proceed

Some screenshots kindly provided from original reporter below:

https://user-images.githubusercontent.com/41326532/112163215-b88d3b80-8be4-11eb-9546-29ae3b4b3fa7.png

Do not alter or remove anything below. The following sections will be managed by moderators only.

Acceptance criteria

• The fallback adblocker detection mechanism should receive "no adblocker" in the case of a redirect to avoid a potential false positive if the subsequent request is blocked

Implementation Brief

• Merge Fix/3018 adblocker fallback #3055

Test Coverage

• No changes (see note in PR)

Visual Regression Changes

• N/A

QA Brief

Engineering QA

• Testing requires the server to be configured to issue a cross origin redirect for /favicon.ico, e.g. http://via.placeholder.com/16
  • Important: the response should not include a Access-Control-Allow-Origin header
• Any adblocker should be deactivated to ensure fallback is triggered
• Trigger adblocker check by going to Connect services with AdSense inactive
• See favicon request triggers redirect but does not result in an "adblocker detected" warning/error

Standard QA

• Test general adblocker detection continues to work as expected with various adblockers
  (uBlock Origin, AdBlock (Plus), AdGuard)

Changelog entry

• Fix Ad Blocker detection issue which occurred on sites with GoDaddy CDN enabled.