appwrite/src/Appwrite/Network/Validator/CNAME.php

<?php

namespace Appwrite\Network\Validator;

use Utopia\Validator;

class CNAME extends Validator
{
    /**
     * @var int
     */
    protected $target;

    /**
     * @param string $target
     */
    public function __construct($target)
    {
        $this->target = $target;
    }

    public function getDescription()
    {
        return 'Invalid CNAME record';
    }

    /**
     * Check if CNAME record target value matches selected target
     * 
     * @param string $domain
     *
     * @return bool
     */
    public function isValid($domain)
    {
        try {
            $records = \dns_get_record($domain, DNS_CNAME);
        } catch (\Throwable $th) {
            return false;
        }

        if(!$records || !\is_array($records)) {
            return false;
        }

        foreach($records as $record) {
            if(isset($record['target']) && $record['target'] === $this->target) {
                return true;
            }
        }

        return false;
    }
}