htaccess force www not for cdn

Question

I have a problem with .htaccess forcing www.

I have the main site http://www.portalesardegna.com and I want to redirect http://portalesardegna.com to the www version, but I have even a CDN, http://cdn.portalesardegna.com , if I look the site with pingdom http://tools.pingdom.com /fpt/#!/eHy16D/www.portalesardegna.com all the files in the cdn are redirected to the www version.

Some information that can be useful:

1. The CDN is on an external service, and the dns point to another server, not mine.
2. I have some images from another subdomain in my site, private3.portalesardegna.com, and all of these images are not redirected.

Here is the code i use in the htaccess

RewriteCond %{HTTPS} !=on
RewriteCond %{HTTP_HOST} !^$
RewriteCond %{HTTP_HOST} !^cdn\..+$ [NC]
RewriteCond %{HTTP_HOST} !^www\..+$ [NC]
RewriteRule ^ http://www.%{HTTP_HOST}%{REQUEST_URI} [R=301,L]

Answer 1

Try this rule as as your very first rule in your root .htaccess file:

RewriteEngine On

RewriteCond %{HTTPS} off
RewriteCond %{HTTP_HOST} !^(cdn|www)\. [NC]
RewriteRule ^ http://www.%{HTTP_HOST}%{REQUEST_URI} [R=301,L,NE]