redirect non-www to www while preserving protocol

Question

I am aware of the fact that there are tons of questions in this section and in server fault dealing with re-directions from non-www to www URLs. But I couldn't find one dealing with this issue while preserving protocol. I am no mod-rewrite expert, and my code is just copy/pasted... here's what i have:

RewriteCond %{HTTP_HOST} ^domain.tld$ [NC]
RewriteRule ^(.*)$ http://www.domain.tld$1 [R=301,L]

So now http://domain.tld and https://domain.tld are forwarded to http://domain.tld

How do i make it so that HTTPS stays on HTTPS while HTTP stays on HTTP?

Answer 1

Just a little information. Best practices indicate that trafic from http has to be redirected to https. If your site is reachable on https, no more need to http.

I think you can associate no-www redirection to www with http redirection to https.

Moreover, be careful of duplicate content if your site is reachable with http and https.