Assign or Execute a controller action to a url if subdomain is found

Question

If a URL will contain a sub domain like http://raddyx.sharemybucket.com./ then I want to execute a controller action for that and the sub domain as its parameter.For Ex for above URL I want execute Users controller and profile action with raddyx as its parameter.

Ex : http://raddyx.sharemybucket.com/ for this I want to execute

http://sharemybucket.com/users/profile/raddyx