servnest/fn/reg.php

<?php

function regGetUpperDomain($domain) {
	// Remove anything before the first dot and the first dot itself
	return preg_replace("/^[^.]+\./", "", $domain);
}

function regListUserDomains($username) {
	return query('select', 'registry', ['username' => $username], 'domain');
}

function regCheckDomainPossession($domain) {
	checkAbsoluteDomainFormat($domain);

	$ownedDomains = regListUserDomains($_SESSION['username']);

	if (in_array($domain, $ownedDomains, true) !== true)
		userError("You don't own this domain.");
}

function regIsFree($domain) {
	foreach (query('select', 'registry', ['domain' => $domain], 'domain')) {

	}

}