Redirection for unfound assets to dropbox for padrino

gistfile1.rb

  error 404 do
    link = "http://dl.dropbox.com/u/#{dropboxid}/#{public_folder}"+request.path_info
    uri = URI.parse(link)
    response = nil
    Net::HTTP.start(uri.host, uri.port) { |http|
      response = http.head(uri.path.size > 0 ? uri.path : "/")}
    if response.code == "200"
      redirect link
    else
      redirect '/'  #any place you like, can be 404 page.
    end
  end