EmailValidator.php

<?php

/*
 * This file is part of the Symfony package.
 *
 * (c) Fabien Potencier <fabien@symfony.com>
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */
namespace Symfony\Component\Validator\Constraints;

use Symfony\Component\Validator\Constraint;
use Symfony\Component\Validator\ConstraintValidator;
use Symfony\Component\Validator\Exception\UnexpectedTypeException;

/**
 * @author Bernhard Schussek <bschussek@gmail.com>
 *
 * @api
 */
class EmailValidator extends ConstraintValidator {

  /**
   * {@inheritDoc}
   */
  public function validate($value, Constraint $constraint) {
    if (null === $value || '' === $value) {
      return;
    }
    if (!is_scalar($value) && !(is_object($value) && method_exists($value, '__toString'))) {
      throw new UnexpectedTypeException($value, 'string');
    }
    $value = (string) $value;
    $valid = filter_var($value, FILTER_VALIDATE_EMAIL);
    if ($valid) {
      $host = substr($value, strpos($value, '@') + 1);
      if (version_compare(PHP_VERSION, '5.3.3', '<') && strpos($host, '.') === false) {

        // Likely not a FQDN, bug in PHP FILTER_VALIDATE_EMAIL prior to PHP 5.3.3
        $valid = false;
      }

      // Check for host DNS resource records
      if ($valid && $constraint->checkMX) {
        $valid = $this
          ->checkMX($host);
      }
      elseif ($valid && $constraint->checkHost) {
        $valid = $this
          ->checkHost($host);
      }
    }
    if (!$valid) {
      $this->context
        ->addViolation($constraint->message, array(
        '{{ value }}' => $value,
      ));
    }
  }

  /**
   * Check DNS Records for MX type.
   *
   * @param string $host Host
   *
   * @return Boolean
   */
  private function checkMX($host) {
    return checkdnsrr($host, 'MX');
  }

  /**
   * Check if one of MX, A or AAAA DNS RR exists.
   *
   * @param string $host Host
   *
   * @return Boolean
   */
  private function checkHost($host) {
    return $this
      ->checkMX($host) || (checkdnsrr($host, "A") || checkdnsrr($host, "AAAA"));
  }

}