Bug 280666 – Add Quirks for changing the navigator.Language because of fingerprinting for logging

• Status: RESOLVED
• Resolution: FIXED
• Component: WebKit Misc.

[Karl Dubost]

When a user is trying to log in on the bestbuy.com website 
with Safari set as Japanese (Accept-Language: ja) or French-France (Accept-Language: fr-FR), 
the login is not working.

While at the same time this is working for Chrome and Firefox. 
Also some other languages will be accepted, even things such as French-Canada


Safari:

PASS Accept-Language: en-US,en;q=0.9
PASS Accept-Language: pt-BR,pt;q=0.9
PASS Accept-Language: fr-CA,fr;q=0.9

FAIL Accept-Language: fr-FR,fr;q=0.9
FAIL Accept-Language: ja


Firefox:
PASS Accept-Language: en-US,en;q=0.8,fr-FR;q=0.5,ja;q=0.3
PASS Accept-Language: fr-FR
PASS Accept-Language: ja



We also tried with Safari and overriding the User-Agent to be Firefox.

Not working:
* Accept-Language: ja
* User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:127.0) Gecko/20100101 Firefox/127.0


And it fails on Firefox with a Safari UA override.

* Accept-Language: fr-FR
* User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/18.2 Safari/605.1.15


bestbuy.com doesn't send a spanish speaking version of the site to users with 
Accept-Language: es-US,es-419;q=0.9,es;q=0.8

So we can probably test a Accept-Language override in English without issues. 



In parallel, an outreach effort will be started to contact Best Buy

[Karl Dubost]

<rdar://136235936>

[Karl Dubost]

Outreach effort at https://github.com/webcompat/web-bugs/issues/142261

[Karl Dubost]

I initially though it was Accept-Language, but that's more complex.

There is language detection everywhere on the client side.
So one solution would be to override the navigator.Language.

[Karl Dubost]

Override navigator.language and navigator.languages to return English values for bestbuy.com. This:

Fixes the getBrowserLocale() call returning "ja" → now returns "en-US"
Fixes the environment initialization matching "en-US" correctly
Fixes the fingerprint hash including the correct language value
Fixes all downstream navigator.language reads (analytics, device info, etc.)

[Karl Dubost]

Pull request: https://github.com/WebKit/WebKit/pull/62170

[EWS]

Committed 310760@main (8655616b4d00): <https://commits.webkit.org/310760@main>

Reviewed commits have been landed. Closing PR #62170 and removing active labels.