regex - htaccess compare cookie value and redirect if evaluation returns true/false

Question

I would like somebody to help me with an if-else statement in htaccess. What I want is htaccess to read a cookie and check if its value equals a defined value. If it evaluates to false, it should excecute a redirect and prevent from the requested folder to be accessed. Maybe a deny from all would be better if the evaluation returns false.

I know that the following code checks if a named cookie value is set. If it is not set, it will execute the rewrite rule below it. But how can I adjust this line so that it checks if it equals a certain value?

RewriteEngine On
RewriteCond %{HTTP_COOKIE} !^.*cookie_name.*$ [NC]
RewriteRule .* http://www.google.com [NC,L]

What I would like, but in .htaccess style:

if ($_COOKIE['cookie_name'] != 'specific_value'){
//rewrite_rule or deny from all.
}

Answer 1

You're close. The cookie string needs a =:

RewriteEngine On
RewriteCond %{HTTP_COOKIE} !cookie_name=specific_value; [NC]
RewriteRule ^ http://www.google.com [NC,L]