instance method check_ip

# File actionpack/lib/action_dispatch/middleware/remote_ip.rb, line 196
      def check_ip(client_ips, forwarded_ips)
        if client_ips.last && forwarded_ips.last && !forwarded_ips.include?(client_ips.last)
          # We don't know which came from the proxy, and which from the user
          raise_spoofing_error
        end

        if @req.get_header("HTTP_FORWARDED") && @req.x_forwarded_for
          x_forwarded_ips = XForwardedForParser.new("HTTP_X_FORWARDED_FOR" => @req.x_forwarded_for).forwarded_for || []
          x_forwarded_client = first_non_proxy(sanitize_ips(x_forwarded_ips).reverse!)
          forwarded_client = first_non_proxy(forwarded_ips)

          # Compare strings, not parsed addresses, so the client cannot choose how its
          # own address is spelled.
          if x_forwarded_client && x_forwarded_client != forwarded_client
            raise_spoofing_error
          end
        end
      end