Cookie Expiring Date

[Steven Tönsing]

Hi everyone,
I'm just trying to get the vanish 2.0.2 running in front of a cms. The  
problem is, the user need to be passed to the backend if the "admin"  
cookie is set and valid.
Therefore i'm wondering if there is a way to find out if the expiring  
date of a cookie is in the future or in the past.

My vcl is something like this.

    if ( (req.http.cookie ~ "MYCOOKIE") &&  
(isExpiringDateOfCookieInFuture) ){
        pass;
     }

Thanks Steven