In ACS 3.x there was a request-processor feature, ForceHostP, that
would make the request-processor always redirect folks to some URL
that you wanted, say, www.foobar.com, if they came requesting some
other URL, such as foobar.com without the www., or
www.someotherurl.org, for example.
I kind of liked that, being able to access your site using whatever
URL they want, but always redirecting them to the canonical URL.
So I implemented this, and uploaded a patch to the SDM.
If there's enough interest, I can perhaps clean it up a bit,
parameterize it, test to see that it works with hostmap, which I'm
not sure it does at the moment.
The patch is here:
https://openacs.org/sdm/one-patch.tcl?patch_id=356
/Lars