Kontaktformular - E-Mail überprüfen

<?php
  /**
   * Squiloople Framework
   *
   * LICENSE: Feel free to use and redistribute this code.
   *
   * @author Michael Rushton <michael@squiloople.com>
   * @link http://squiloople.com/
   * @package Squiloople
   * @version 1.0
   * @copyright © 2012 Michael Rushton
   */




  final class EmailAddressValidator
  {
    const RFC_5321 = 5321;
    const RFC_5322 = 5322;
    private $_email_address;
    private $_quoted_string = FALSE;
    private $_obsolete = FALSE;
    private $_basic_domain_name = TRUE;
    private $_domain_literal = FALSE;
    private $_cfws = FALSE;




    public function __construct($email_address, $standard = NULL)
    {
      $this->_email_address = $email_address;
      switch ($standard)
      {
        case NULL:
          break;
        case self::RFC_5321:
          $this->setStandard5321();
          break;
        case self::RFC_5322:
          $this->setStandard5322();
          break;
        default:
          throw new Exception('Unknown RFC standard for email address validation.');
      }
    }




    public static function setEmailAddress($email_address, $standard = NULL)
    {
      return new self($email_address, $standard);
    }




    public function setStandardBasic()
    {
      $this->_quoted_string = FALSE;
      $this->_obsolete = FALSE;
      $this->_basic_domain_name = TRUE;
      $this->_domain_literal = FALSE;
      $this->_cfws = FALSE;
      return $this;
    }




    public function setStandard5321()
    {
      $this->_quoted_string = TRUE;
      $this->_obsolete = FALSE;
      $this->_basic_domain_name = FALSE;
      $this->_domain_literal = TRUE;
      $this->_cfws = FALSE;
      return $this;
    }




    public function setStandard5322()
    {
      $this->_quoted_string = FALSE;
      $this->_obsolete = TRUE;
      $this->_basic_domain_name = FALSE;
      $this->_domain_literal = TRUE;
      $this->_cfws = TRUE;
      return $this;
    }




    public function setQuotedString($allow = TRUE)
    {
      $this->_quoted_string = $allow;
      return $this;
    }




    public function setObsolete($allow = TRUE)
    {
      $this->_obsolete = $allow;
      return $this;
    }




    public function setBasicDomainName($allow = TRUE)
    {
      $this->_basic_domain_name = $allow;
      return $this;
    }




    public function setDomainLiteral($allow = TRUE)
    {
      $this->_domain_literal = $allow;
      return $this;
    }




    public function setCFWS($allow = TRUE)
    {
      $this->_cfws = $allow;
      return $this;
    }




    private function _getDotAtom()
    {
      return "([!#-'*+\/-9=?^-~-]+)(?>\.(?1))*";
    }




    private function _getQuotedString()
    {
      return '"(?>[ !#-\[\]-~]|\\\[ -~])*"';
    }




    private function _getObsolete()
    {
      return '([!#-\'*+\/-9=?^-~-]+|"(?>'
        . $this->_getFWS()
        . '(?>[\x01-\x08\x0B\x0C\x0E-!#-\[\]-\x7F]|\\\[\x00-\xFF]))*'
        . $this->_getFWS()
        . '")(?>'
        . $this->_getCFWS()
        . '\.'
        . $this->_getCFWS()
        . '(?1))*';
    }




    private function _getDomainName()
    {
      if ($this->_basic_domain_name)
      {
        return '(?>' . $this->_getDomainNameLengthLimit()
          . '[a-z\d](?>[a-z\d-]*[a-z\d])?'
          . $this->_getCFWS()
          . '\.'
          . $this->_getCFWS()
          . '){1,126}[a-z]{2,6}';
      }
      return $this->_getDomainNameLengthLimit()
        . '([a-z\d](?>[a-z\d-]*[a-z\d])?)(?>'
        . $this->_getCFWS()
        . '\.'
        . $this->_getDomainNameLengthLimit()
        . $this->_getCFWS()
        . '(?2)){0,126}';
    }




    private function _getIPv6()
    {
      return '([a-f\d]{1,4})(?>:(?3)){7}|(?!(?:.*[a-f\d][:\]]){8,})((?3)(?>:(?3)){0,6})?::(?4)?';
    }




    private function _getIPv4MappedIPv6()
    {
      return '(?3)(?>:(?3)){5}:|(?!(?:.*[a-f\d]:){6,})(?5)?::(?>((?3)(?>:(?3)){0,4}):)?';
    }




    private function _getIPv4()
    {
      return '(25[0-5]|2[0-4]\d|1\d{2}|[1-9]?\d)(?>\.(?6)){3}';
    }




    private function _getDomainLiteral()
    {
      return '\[(?:(?>IPv6:(?>'
        . $this->_getIPv6()
        . '))|(?>(?>IPv6:(?>'
        . $this->_getIPv4MappedIPv6()
        . '))?'
        . $this->_getIPv4()
        . '))\]';
    }




    private function _getFWS($define = FALSE)
    {
      if ($this->_cfws)
      {
        return !$define ? '(?P>fws)' : '(?<fws>(?>(?>(?>\x0D\x0A)?[\t ])+|(?>[\t ]*\x0D\x0A)?[\t ]+)?)';
      }
    }




    private function _getComments()
    {
      return '(?<comment>\((?>'
        . $this->_getFWS()
        . '(?>[\x01-\x08\x0B\x0C\x0E-\'*-\[\]-\x7F]|\\\[\x00-\x7F]|(?P>comment)))*'
        . $this->_getFWS()
        . '\))';
    }




    private function _getCFWS($define = FALSE)
    {
      if ($this->_cfws && !$define)
      {
        return '(?P>cfws)';
      }




      if ($this->_cfws)
      {
        return '(?<cfws>(?>(?>(?>'
          . $this->_getFWS(TRUE)
          . $this->_getComments()
          . ')+'
          . $this->_getFWS()
          . ')|'
          . $this->_getFWS()
          . ')?)';
      }
    }




    private function _getLocalPart()
    {
      if ($this->_obsolete)
      {
        return $this->_getObsolete();
      }
      if ($this->_quoted_string)
      {
        return '(?>' . $this->_getDotAtom() . '|' . $this->_getQuotedString() . ')';
      }




      return $this->_getDotAtom();
    }




    private function _getDomain()
    {
      if ($this->_domain_literal)
      {
        return '(?>' . $this->_getDomainName() . '|' . $this->_getDomainLiteral() . ')';
      }




      return $this->_getDomainName();
    }




    private function _getEmailAddressLengthLimit()
    {
      return '(?!(?>' . $this->_getCFWS() . '"?(?>\\\[ -~]|[^"])"?' . $this->_getCFWS() . '){255,})';
    }




    private function _getLocalPartLengthLimit()
    {
      return '(?!(?>' . $this->_getCFWS() . '"?(?>\\\[ -~]|[^"])"?' . $this->_getCFWS() . '){65,}@)';
    }




    private function _getDomainNameLengthLimit()
    {
      return '(?!' . $this->_getCFWS() . '[a-z\d-]{64,})';
    }




    private function _verifyDomain($domain)
    {
      if (!checkdnsrr(end($domain), 'MX'))
      {
        return 0;
      }
      return TRUE;
    }




    public function isValid($verify = FALSE)
    {
      if (!preg_match(
          '/^'
        . $this->_getEmailAddressLengthLimit()
        . $this->_getLocalPartLengthLimit()
        . $this->_getCFWS()
        . $this->_getLocalPart()
        . $this->_getCFWS()
        . '@'
        . $this->_getCFWS()
        . $this->_getDomain()
        . $this->_getCFWS(TRUE)
        . '$/isD'
        , $this->_email_address
      ))
      {
        return FALSE;
      }




      if ($verify)
      {
        return $this->_verifyDomain(explode('@', $this->_email_address));
      }




      return 1;
    }
  }