use HTTP_X_FORWARDED_PROTO when behind a proxy

[blink38]

When behind a proxy, absolute root url is construct using HTTP_X_FORWARDED_HOST but is ignoring the scheme.

The modification proposed is to use HTTP_X_FORWARDED_PROTO which include the scheme when construct the absolute root url.

Use case :
Piwigo is running in docker container which expose the service with HTTP. A traefik proxy is exposing the service via HTTPs. Without this modification, url are return with http:// scheme.

May resolve issue #1527

[gasparakos]

It is working for Us!

Our system runs in docker, behind an apache reverse proxy. Container port 80 is exposed on 12380. On apache RequestHeader set X-Forwarded-Proto 'https' was set but some functionality didn't worked, eg: file upload or mobile client show only white square insted of pictures. After apply 4eb8765 problems was resolved.

Thank You!

[mossroy]

For information, I had created an almost identical PR 6 years ago: #483 (that was not merged either, unfortunately)

To me, this is still relevant, and I still workaround it with the following code in local/config/config.inc.php:

if ($_SERVER['HTTP_X_FORWARDED_PROTO'] == 'https'){
       $_SERVER['HTTPS']='on';
}

[plegall]

I close this pull-request, as a duplicate of #483

[blink38]

The proposed code by @mossroy #1637 (comment) is a workaround, waiting for the MR (#483 or #1637) to be accepted.

It's not relevant to say : the solution is to put the fix code in the config.php instead of correcting the code where it must be done.