Add domain rule

[arogachev]

No description provided.

[samdark]

Need option to support wildcards.

Could be done with filter_var:

if ($allowWildcard) {
    $host = str_replace('*', 'wildcard', $host);
}

if (!filter_var($host, FILTER_VALIDATE_DOMAIN, FILTER_FLAG_HOSTNAME)) {
  // invalid
}