sanitize_string

# File actionpack/lib/action_dispatch/middleware/host_authorization.rb, line 72
        def sanitize_string(host)
          if host.start_with?(".")
            /\A([a-z0-9-]+\.)?#{Regexp.escape(host[1..-1])}#{PORT_REGEX}?\z/
          else
            /\A#{Regexp.escape host}#{PORT_REGEX}?\z/
          end
        end