friendica-github/mod/dfrn_notify.php

<?php





function dfrn_notify_post(&$a) {

	$dfrn_id = notags(trim($_POST['dfrn_id']));
	$challenge = notags(trim($_POST['challenge']));
	$data = $_POST['data'];

	$r = q("SELECT * FROM `challenge` WHERE `dfrn-id` = '%s' AND `challenge` = '%s' LIMIT 1",
		dbesc($dfrn_id),
		dbesc($challenge)
	);
	if(! count($r))
		xml_status(3);

	$r = q("DELETE FROM `challenge` WHERE `dfrn-id` = '%s' AND `challenge` = '%s' LIMIT 1",
		dbesc($dfrn_id),
		dbesc($challenge)
	);







}












function dfrn_notify_content(&$a) {

	if(x($_GET,'dfrn_id')) {
		// initial communication from external contact
		$hash = random_string();

		$status = 0;

		$r = q("DELETE FROM `challenge` WHERE `expire` < " . intval(time()));

		$r = q("INSERT INTO `challenge` ( `challenge`, `dfrn-id`, `expire` )
			VALUES( '%s', '%s', '%s') ",
			dbesc($hash),
			dbesc(notags(trim($_GET['dfrn_id']))),
			intval(time() + 60 )
		);

		$r = q("SELECT * FROM `contact` WHERE `issued-id` = '%s' AND `blocked` = 0 LIMIT 1",
			dbesc($_GET['dfrn_id']));
		if((! count($r)) || (! strlen($r[0]['prvkey'])))
			$status = 1;

		$challenge = '';

		openssl_private_encrypt($hash,$challenge,$r[0]['prvkey']);

		echo '<?xml version=1.0" encoding="UTF-8"?><dfrn_notify><status>' .$status . '</status><dfrn_id>' . $_GET['dfrn_id'] . '</dfrn_id>'
			. '<challenge>' . $challenge . '</challenge></dfrn_notify>' . "\r\n" ;
		session_write_close();
		exit;
		
	}

}