sanitize_ips

# File actionpack/lib/action_dispatch/middleware/remote_ip.rb, line 184
      def sanitize_ips(ips) # :doc:
        ips.select! do |ip|
          # Only return IPs that are valid according to the IPAddr#new method.
          range = IPAddr.new(ip).to_range
          # We want to make sure nobody is sneaking a netmask in.
          range.begin == range.end
        rescue ArgumentError
          nil
        end
        ips
      end