use XML::Simple;

use strict;
use warnings;

my $xml = XMLin('<config ip="127.0.0.1" port="12345"><timeout>1000</timeout><timeout>2000</timeout></config>');
print XMLout($xml);

##</code><code>##

<opt ip="127.0.0.1" port="12345">
  <timeout>1000</timeout>
  <timeout>2000</timeout>
</opt>