Downloading file in padrino/sinatra

gistfile1.rb

Server.controllers :installer, :parent => :licenses do  
  before do
    puts params.inspect
    @license = License.get(params[:license_id])
    halt 404, "License not found" unless @license
  end
    
  get :index, :with => :token do
    halt 404, "File not found" if @license.installer.token != params[:token]
    # installer.path is something like c:/installers/install.exe
    send_file(@license.installer.path)
  end
end