I'm using the casrack-the-authenticator gem for CAS authentication. My server is running Thin on top of Sinatra. I've gotten the CAS authentication bit working, but I'm not sure how to tell Rack to intercept "/index.html" requests to confirm the CAS login, and if the user is not allowed to view the page, return a HTTP 403 response instead of serving the actual page. Does anyone have experience with this? Thanks.

My app:

class Foo < Sinatra::Base
    enable :sessions
    set :public, "public"
    use CasrackTheAuthenticator::Simple, :cas_server => "https://my.cas_server.com"
    use CasrackTheAuthenticator::RequireCAS
end

My rackup file:

require 'foo'

use Rack::CommonLogger
use Rack::Lint

run Foo