Hi -- we currently have a redirect rule in a location on our server to redirect all non-SSL traffic to SSL, like so:

location / {
return 301 https://$server_name$request_uri;
}

This works for almost all cases, but there is an edge case that is broken by this.
We have a custom subdomain functionality that our users use to give them more personalised-looking URLs, so they can use <username>.oursite.com
So username.oursite.com should redirect to https://username.oursite.com
And otheruser.oursite.com should redirect to https://otheruser.oursite.com

Could anyone advise me on what redirect rule I should use to achieve what our current rule does (redirects almost all traffic to HTTPS), and also redirects the special case.

Thanks very much for any and all assistance,
Doug.