friendica/mod/opensearch.php

<?php

use Friendica\App;

function opensearch_content(App $a) {

	$tpl = get_markup_template('opensearch.tpl');

	header("Content-type: application/opensearchdescription+xml");

	$o = replace_macros($tpl, array(
		'$baseurl' => App::get_baseurl(),
		'$nodename' => $a->get_hostname(),
	));

	echo $o;

	killme();
}