ConnectivityChecker: Remove double // in aliveCheckUrl causing Invalid Redirect URL with CloudFlare Access.

[bchavez]

Description

Bug Fix

When Homer is protected behind CloudFlare Access, the ConnectivityChecker builds an aliveCheckUrl with something like:

https://homer.domain.net//index.html?t=1666582254399

and makes an HTTP HEAD to the homer.domain.net to verify connectedness.

The problem arises when the cookie protecting homer.domain.net is expired; and results in an HTTP 302 redirect to a login page.

The browser follows the HTTP 302 redirect and the user lands on a site like:

https://__team__.cloudflareaccess.com/cdn-cgi/access/login/....redirect_url=%2F%2Findex.html%3Ft%3D1666582258096....

Notice the URL encode redirect_url=%2F%2Findex.html. Decoded, the redirect_url looks something like //index.html. The double // in the redirect_url causes CloudFlare Access to display the following error page (instead of a proper Login Page or Redirect):

If we remove the leading %2F from the redirect_url so that we have: redirect_url=%2Findex.html...; we get the expected login page and/or a proper redirect with the necessary authorization cookies.

Feel free to push modifications or changes to this PR.

Thanks,
Brian

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist:

• I've read & comply with the contributing guidelines
• I have tested my code for new features & regressions on both mobile & desktop devices, using the latest version of major browsers.
• I have made corresponding changes to the documentation (README.md).
• I've checked my modifications for any breaking changes, especially in the config.yml file

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[bastienwirtz]

Hi @bchavez,

Indeed, the location.pathname can contain a trailing slash and cause a double slash. Thanks for this fix!

[XxAcielxX]

Same issue is happening if you use Authelia as an authentication method. After the login, it redirects to https://mydomain.ltd//index.html?t=1667722753069

Even if the ConnectivityChecker is set to false this happens randomly. On true, it always happens.

[XxAcielxX]

I'm having a side affect of this fix with the redirecting. Now if I'm on https://mydomain.ltd//index.html, the redirect adds another
/index.html?t=xxxxxxxxxxx and I end up with https://mydomain.ltd/index.html/index.html?t=xxxxxxxxxxx

[martin-micimo]

Yea. Same as #468

Why was the index.html hardcoded here? Works fine if I remove "/index.html" from aliveCheckUrl in the compiled js.