ENH Also check BASE_URL in host

[emteknetnz]

Issue #10156

Recipe test

• Test/4/director base url emteknetnz/recipe-kitchen-sink#1

[michalkleiner]

I'm not 100% sure about the change.

On a correctly configured site (having the BASE_URL configured), with this change, it would always trump any Host header or HTTP_HOST server variable. That basically removes the functionality where a site can respond to multiple domains and let PHP decide what to do with it because it will always behave as on the single domain coming from BASE_URL.

[emteknetnz]

That's a good point, probably makes sense to move the call to baseURL() to lower down in the host() method

[emteknetnz]

On further inspection this is a pretty pointless PR.

$default_base_url comes from SS_BASE_URL https://github.com/silverstripe/silverstripe-framework/blob/4/src/Control/Director.php#L95

Which is also what feeds BASE_URL https://github.com/silverstripe/silverstripe-framework/blob/4/src/includes/constants.php#L111

[michalkleiner]

The change now corresponds with what was already expected based on the method's docblock, and I think we could merge this, however, I'm not sure it solves the problem we discussed privately which might be coming from the place where it uses the current request to get the Host header.

EDIT: Ok to close if it functionally doesn't improve over the current state covered by other methods.