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// RFC 5322
function isValid5322($emailAddress)
{
return preg_match('/^((?>(?>(?>((?>[ ]+(?>\x0D\x0A[ ]+)*)?)(\((?>(?2)(?>[\x01-\x08\x0B\x0C\x0E-\'*-\[\]-\x7F]|\\\[\x00-\x7F]|(?3)))*(?2)\)))+(?2))|(?2))?)([!#-\'*+\/-9=?^-~-]+|"(?>(?2)(?>[\x01-\x08\x0B\x0C\x0E-!#-\[\]-\x7F]|\\\[\x00-\x7F]))*(?2)")(?>(?1)\.(?1)(?4))*(?1)@(?1)(?>([a-z0-9](?>[a-z0-9-]*[a-z0-9])?)(?>(?1)\.(?1)(?5)){0,126}|\[(?:(?>IPv6:(?>([a-f0-9]{1,4})(?>:(?6)){7}|(?!(?:.*[a-f0-9][:\]]){8,})((?6)(?>:(?6)){0,6})?::(?7)?))|(?>(?>IPv6:(?>(?6)(?>:(?6)){5}:|(?!(?:.*[a-f0-9]:){6,})(?8)?::(?>((?6)(?>:(?6)){0,4}):)?))?(25[0-5]|2[0-4][0-9]|1[0-9]{2}|[1-9]?[0-9])(?>\.(?9)){3}))\])(?1)$/isD', $emailAddress);
}
// RFC 5321
function isValid5321($emailAddress)
{
return preg_match('/^(?>([!#-\'*+\/-9=?^-~-]+)(?>\.(?1))*|"(?>[ !#-\[\]-~]|\\\[ -~])*")@(?>([a-z0-9](?>[a-z0-9-]*[a-z0-9])?)(?>\.(?2)){0,126}|\[(?:(?>IPv6:(?>([a-f0-9]{1,4})(?>:(?3)){7}|(?!(?:.*[a-f0-9][:\]]){8,})((?3)(?>:(?3)){0,6})?::(?4)?))|(?>(?>IPv6:(?>(?3)(?>:(?3)){5}:|(?!(?:.*[a-f0-9]:){6,})(?5)?::(?>((?3)(?>:(?3)){0,4}):)?))?(25[0-5]|2[0-4][0-9]|1[0-9]{2}|[1-9]?[0-9])(?>\.(?6)){3}))\])$/iD', $emailAddress);
}
At 585 characters long (for validation according to the more expansive RFC 5322), it is quite complicated. However, it is much simpler than other regexes which try to validate every RFC-compliant address (and using out-dated RFCs as well), which range in the high thousands. But, still, it may be too complex for some. Which is why I've written an article on Email Address Validation which explains step-by-step the construction of the regular expression -- what part validates what -- and then provided a class which allows for easy manipulation of the regex (you can toggle on and off quoted-string, domain literals, internationalized labels, CFWS etc.). It can then be used both by those who want a simple validator and by those who want to accept every RFC 5321/5322 compliant email address.
And here it is as a class:
Code: Select all
/**
* Squiloople Framework
*
* LICENSE: Feel free to use and redistribute this code.
*
* @author Michael Rushton <michael@squiloople.com>
* @link http://squiloople.com/
* @category Squiloople
* @package Models
* @subpackage Validators
* @version 1.0
* @copyright Copyright © 2009-2010 Michael Rushton
*/
namespace Models\Validators;
/**
* Email Address Validator
*
* Validate email addresses according to RFC 5321 or RFC 5322
*/
final class EmailAddressValidator
{
/**
* The email address to validate
*
* @access private
* @var string $_emailAddress
*/
private $_emailAddress;
/**
* A quoted string local part is either allowed (true) or not (false)
*
* @access private
* @var bool $_quotedString
*/
private $_quotedString = false;
/**
* An obsolete local part is either allowed (true) or not (false)
*
* @access private
* @var bool $_obsolete
*/
private $_obsolete = false;
/**
* A domain literal domain is either allowed (true) or not (false)
*
* @access private
* @var bool $_domainLiteral
*/
private $_domainLiteral = false;
/**
* Comments and folding white spaces are either allowed (true) or not (false)
*
* @access private
* @var bool $_cfws
*/
private $_cfws = false;
/**
* Set the email address and turn on the relevant standard if required
*
* @access public
* @param string $emailAddress
* @param integer $standard
*/
public function __construct($emailAddress, $standard = null)
{
// Set the email address
$this->_emailAddress = $emailAddress;
// Turn on the RFC 5321 standard if requested
if ($standard == 5321)
{
$this->setStandard5321();
}
// Otherwise turn on the RFC 5322 standard if requested
if ($standard == 5322)
{
$this->setStandard5322();
}
}
/**
* Call the constructor fluently
*
* @access public
* @static
* @param string $emailAddress
* @param integer $standard
* @return \Models\Validators\EmailAddressValidator
*/
public static function setEmailAddress($emailAddress, $standard = null)
{
return new self($emailAddress, $standard);
}
/**
* Validate the email address according to RFC 5321 and return itself
*
* @access public
* @param bool $allow
* @return \Models\Validators\EmailAddressValidator
*/
public function setStandard5321($allow = true)
{
// A quoted string local part is either allowed (true) or not (false)
$this->_quotedString = $allow;
// A domain literal domain is either allowed (true) or not (false)
$this->_domainLiteral = $allow;
// Return itself
return $this;
}
/**
* Validate the email address according to RFC 5322 and return itself
*
* @access public
* @param bool $allow
* @return \Models\Validators\EmailAddressValidator
*/
public function setStandard5322($allow = true)
{
// An obsolete local part is either allowed (true) or not (false)
$this->_obsolete = $allow;
// A domain literal domain is either allowed (true) or not (false)
$this->_domainLiteral = $allow;
// Comments and folding white spaces are either allowed (true) or not (false)
$this->_cfws = $allow;
// Return itself
return $this;
}
/**
* Either allow (true) or disallow (false) a quoted string local part and return itself
*
* @access public
* @param bool $allow
* @return \Models\Validators\EmailAddressValidator
*/
public function setQuotedString($allow = true)
{
// Either allow (true) or disallow (false) a quoted string local part
$this->_quotedString = $allow;
// Return itself
return $this;
}
/**
* Either allow (true) or disallow (false) an obsolete local part and return itself
*
* @access public
* @param bool $allow
* @return \Models\Validators\EmailAddressValidator
*/
public function setObsolete($allow = true)
{
// Either allow (true) or disallow (false) an obsolete local part
$this->_obsolete = $allow;
// Return itself
return $this;
}
/**
* Either allow (true) or disallow (false) a domain literal domain and return itself
*
* @access public
* @param bool $allow
* @return \Models\Validators\EmailAddressValidator
*/
public function setDomainLiteral($allow = true)
{
// Either allow (true) or disallow (false) a domain literal domain
$this->_domainLiteral = $allow;
// Return itself
return $this;
}
/**
* Either allow (true) or disallow (false) comments and folding white spaces and return itself
*
* @access public
* @param bool $allow
* @return \Models\Validators\EmailAddressValidator
*/
public function setCFWS($allow = true)
{
// Either allow (true) or disallow (false) comments and folding white spaces
$this->_cfws = $allow;
// Return itself
return $this;
}
/**
* Return the regular expression for a dot atom local part
*
* @access private
* @return string
*/
private function _getDotAtom()
{
return "([!#-'*+\/-9=?^-~-]+)(?>\.(?1))*";
}
/**
* Return the regular expression for a quoted string local part
*
* @access private
* @return string
*/
private function _getQuotedString()
{
return '"(?>[ !#-\[\]-~]|\\\[ -~])*"';
}
/**
* Return the regular expression for an obsolete local part
*
* @access private
* @return string
*/
private function _getObsolete()
{
return '([!#-\'*+\/-9=?^-~-]+|"(?>'
. $this->_getFWS()
. '(?>[\x01-\x08\x0B\x0C\x0E-!#-\[\]-\x7F]|\\\[\x00-\x7F]))*'
. $this->_getFWS()
. '")(?>'
. $this->_getCFWS()
. '\.'
. $this->_getCFWS()
. '(?1))*';
}
/**
* Return the regular expression for a domain name domain
*
* @access private
* @return string
*/
private function _getDomainName()
{
return '([a-z0-9](?>[a-z0-9-]*[a-z0-9])?)(?>'
. $this->_getCFWS()
. '\.'
. $this->_getCFWS()
. '(?2)){0,126}';
}
/**
* Return the regular expression for an IPv6 address
*
* @access private
* @return string
*/
private function _getIPv6()
{
return '([a-f0-9]{1,4})(?>:(?3)){7}|(?!(?:.*[a-f0-9][:\]]){8,})((?3)(?>:(?3)){0,6})?::(?4)?';
}
/**
* Return the regular expression for an IPv4-mapped IPv6 address
*
* @access private
* @return string
*/
private function _getIPv6v4()
{
return '(?3)(?>:(?3)){5}:|(?!(?:.*[a-f0-9]:){6,})(?5)?::(?>((?3)(?>:(?3)){0,4}):)?';
}
/**
* Return the regular expression for an IPv4 address
*
* @access private
* @return string
*/
private function _getIPv4()
{
return '(25[0-5]|2[0-4][0-9]|1[0-9]{2}|[1-9]?[0-9])(?>\.(?6)){3}';
}
/**
* Return the regular expression for a domain literal domain
*
* @access private
* @return string
*/
private function _getDomainLiteral()
{
return '\[(?:(?>IPv6:(?>'
. $this->_getIPv6()
. '))|(?>(?>IPv6:(?>'
. $this->_getIPv6v4()
. '))?'
. $this->_getIPv4()
. '))\]';
}
/**
* Return either the regular expression for folding white spaces or its backreference if allowed
*
* @access private
* @var bool $define
* @return string
*/
private function _getFWS($define = false)
{
// Return the backreference if $define is set to false otherwise return the regular expression
if ($this->_cfws)
{
return !$define ? '(?P>fws)' : '(?<fws>(?>[ ]+(?>\x0D\x0A[ ]+)*)?)';
}
}
/**
* Return the regular expression for comments
*
* @access private
* @return string
*/
private function _getComments()
{
return '(?<comment>\((?>'
. $this->_getFWS()
. '(?>[\x01-\x08\x0B\x0C\x0E-\'*-\[\]-\x7F]|\\\[\x00-\x7F]|(?P>comment)))*'
. $this->_getFWS()
. '\))';
}
/**
* Return either the regular expression for comments and folding white spaces or its backreference if allowed
*
* @access private
* @var bool $define
* @return string
*/
private function _getCFWS($define = false)
{
// Return the backreference if $define is set to false
if ($this->_cfws && !$define)
{
return '(?P>cfws)';
}
// Otherwise return the regular expression
if ($this->_cfws)
{
return '(?<cfws>(?>(?>(?>'
. $this->_getFWS(true)
. $this->_getComments()
. ')+'
. $this->_getFWS()
. ')|'
. $this->_getFWS()
. ')?)';
}
}
/**
* Establish, and return, the valid format for the local part
*
* @access private
* @return string
*/
private function _getLocalPart()
{
// The local part may be obsolete if allowed
if ($this->_obsolete)
{
return $this->_getObsolete();
}
// Or the local part may be either a dot atom or a quoted string if the latter is allowed
if ($this->_quotedString)
{
return '(?>' . $this->_getDotAtom() . '|' . $this->_getQuotedString() . ')';
}
// Otherwise the local part may only be a dot atom
return $this->_getDotAtom();
}
/**
* Establish, and return, the valid format for the domain
*
* @access private
* @return string
*/
private function _getDomain()
{
// The domain may be either a domain name or a domain literal if the latter is allowed
if ($this->_domainLiteral)
{
return '(?>' . $this->_getDomainName() . '|' . $this->_getDomainLiteral() . ')';
}
// Otherwise the domain must be a domain name
return $this->_getDomainName();
}
/**
* Check to see if the domain can be resolved to MX RRs
*
* @access private
* @param array $domain
* @return bool
*/
private function _verifyDomain($domain)
{
// Return false if the domain cannot be resolved to MX RRs
if (!checkdnsrr(end($domain), 'MX'))
{
return false;
}
// Otherwise return true
return true;
}
/**
* Perform the validation check on the email address's syntax and, if required, call _verifyDomain()
*
* @access public
* @param bool $verify
* @return bool|integer
*/
public function validate($verify = false)
{
// Return false if the email address has an incorrect syntax
if (!preg_match(
'/^'
. $this->_getCFWS()
. $this->_getLocalPart()
. $this->_getCFWS()
. '@'
. $this->_getCFWS()
. $this->_getDomain()
. $this->_getCFWS(true)
. '$/isD'
, $this->_emailAddress
))
{
return false;
}
// Otherwise check to see if the domain can be resolved to MX RRs if required
if ($verify)
{
// Return 0 if the domain cannot be resolved to MX RRs
if (!$this->_verifyDomain(explode('@', $this->_emailAddress)))
{
return 0;
}
// Otherwise return true
return true;
}
// Otherwise return 1
return 1;
}
}
?:[\x01-\x08\x0b\x0c\x0e-\x1f\x21-\x5a\x53-\x7f]|\\[\x01-\x09\x0b\x0c\x0e-\x7f])+)\])