符合RFC的电子邮件地址验证程序

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A php function that correctly validates all parts of a given email address, according to RFCs 5322, 5321, 1123, 2396, 3696, 4291, 4343, 2821 & 2822. I’ve released it under a license that allows you to use it royalty-free in commercial or non-commercial work. The test cases and the latest version of the code will always be here: http://code.google.com/p/isemail/source/browse/#svn/trunk
  1. <?php
  2. /**
  3.  * To validate an email address according to RFCs 5321, 5322 and others
  4.  * 
  5.  * Copyright (c) 2008-2010, Dominic Sayers							<br>
  6.  * Test schema documentation Copyright (c) 2010, Daniel Marschall				<br>
  7.  * All rights reserved.
  8.  * 
  9.  * Redistribution and use in source and binary forms, with or without modification,
  10.  * are permitted provided that the following conditions are met:
  11.  * 
  12.  *     - Redistributions of source code must retain the above copyright notice,
  13.  *       this list of conditions and the following disclaimer.
  14.  *     - Redistributions in binary form must reproduce the above copyright notice,
  15.  *       this list of conditions and the following disclaimer in the documentation
  16.  *       and/or other materials provided with the distribution.
  17.  *     - Neither the name of Dominic Sayers nor the names of its contributors may be
  18.  *       used to endorse or promote products derived from this software without
  19.  *       specific prior written permission.
  20.  * 
  21.  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
  22.  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
  23.  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  24.  * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
  25.  * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
  26.  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  27.  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
  28.  * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  29.  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
  30.  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  31.  * 
  32.  * @package	is_email
  33.  * @author	Dominic Sayers <[email protected]>
  34.  * @copyright	2008-2010 Dominic Sayers
  35.  * @license	http://www.opensource.org/licenses/bsd-license.php BSD License
  36.  * @link	http://www.dominicsayers.com/isemail
  37.  * @version	2.8.3 - Clarified text for ISEMAIL_IPV6BADCHAR and new test #276 added (too many IPv6 groups with an elision)
  38.  */
  39.  
  40. // The quality of this code has been improved greatly by using PHPLint
  41. // Copyright (c) 2010 Umberto Salsi
  42. // This is free software; see the license for copying conditions.
  43. // More info: http://www.icosaedro.it/phplint/
  44. /*.
  45. 	require_module 'standard';
  46. 	require_module 'pcre';
  47. .*/
  48. /**
  49.  * Check that an email address conforms to RFCs 5321, 5322 and others
  50.  *
  51.  * @param string	$email		The email address to check
  52.  * @param boolean	$checkDNS	If true then a DNS check for A and MX records will be made
  53.  * @param mixed		$errorlevel	If true then return an integer error or warning number rather than true or false
  54.  */
  55. /*.mixed.*/ function is_email ($email, $checkDNS = false, $errorlevel = false) {
  56. 	// Check that $email is a valid address. Read the following RFCs to understand the constraints:
  57. 	// 	(http://tools.ietf.org/html/rfc5321)
  58. 	// 	(http://tools.ietf.org/html/rfc5322)
  59. 	// 	(http://tools.ietf.org/html/rfc4291#section-2.2)
  60. 	// 	(http://tools.ietf.org/html/rfc1123#section-2.1)
  61. 	// 	(http://tools.ietf.org/html/rfc3696) (guidance only)
  62.  
  63. 	//	$errorlevel	Behaviour
  64. 	//	---------------	---------------------------------------------------------------------------
  65. 	//	E_ERROR		Return validation failures only. For technically valid addresses return
  66. 	//			ISEMAIL_VALID
  67. 	//	E_WARNING	Return warnings for unlikely but technically valid addresses. This includes
  68. 	//			addresses at TLDs (e.g. [email protected]), addresses with FWS and comments,
  69. 	//			addresses that are quoted and addresses that contain no alphabetic or
  70. 	//			numeric characters.
  71. 	//	true		Same as E_ERROR
  72. 	//	false		Return true for valid addresses, false for invalid ones. No warnings.
  73. 	//
  74. 	//	Errors can be distinguished from warnings if ($return_value > ISEMAIL_ERROR)
  75. // version 2.0: Enhance $diagnose parameter to $errorlevel
  76. // revision 2.5: some syntax changes to make it more PHPLint-friendly. Should be functionally identical.
  77.  
  78. 	if (!defined('ISEMAIL_VALID')) {
  79. 		// No errors
  80. 		define('ISEMAIL_VALID'			, 0);
  81. 		// Warnings (valid address but unlikely in the real world)
  82. 		define('ISEMAIL_WARNING'		, 64);
  83. 		define('ISEMAIL_TLD'			, 65);
  84. 		define('ISEMAIL_TLDNUMERIC'		, 66);
  85. 		define('ISEMAIL_QUOTEDSTRING'		, 67);
  86. 		define('ISEMAIL_COMMENTS'		, 68);
  87. 		define('ISEMAIL_FWS'			, 69);
  88. 		define('ISEMAIL_ADDRESSLITERAL'		, 70);
  89. 		define('ISEMAIL_UNLIKELYINITIAL'	, 71);
  90. 		define('ISEMAIL_SINGLEGROUPELISION'	, 72);
  91. 		define('ISEMAIL_DOMAINNOTFOUND'		, 73);
  92. 		define('ISEMAIL_MXNOTFOUND'		, 74);
  93. 		// Errors (invalid address)
  94. 		define('ISEMAIL_ERROR'			, 128);
  95. 		define('ISEMAIL_TOOLONG'		, 129);
  96. 		define('ISEMAIL_NOAT'			, 130);
  97. 		define('ISEMAIL_NOLOCALPART'		, 131);
  98. 		define('ISEMAIL_NODOMAIN'		, 132);
  99. 		define('ISEMAIL_ZEROLENGTHELEMENT'	, 133);
  100. 		define('ISEMAIL_BADCOMMENT_START'	, 134);
  101. 		define('ISEMAIL_BADCOMMENT_END'		, 135);
  102. 		define('ISEMAIL_UNESCAPEDDELIM'		, 136);
  103. 		define('ISEMAIL_EMPTYELEMENT'		, 137);
  104. 		define('ISEMAIL_UNESCAPEDSPECIAL'	, 138);
  105. 		define('ISEMAIL_LOCALTOOLONG'		, 139);
  106. //		define('ISEMAIL_IPV4BADPREFIX'		, 140);
  107. 		define('ISEMAIL_IPV6BADPREFIXMIXED'	, 141);
  108. 		define('ISEMAIL_IPV6BADPREFIX'		, 142);
  109. 		define('ISEMAIL_IPV6GROUPCOUNT'		, 143);
  110. 		define('ISEMAIL_IPV6DOUBLEDOUBLECOLON'	, 144);
  111. 		define('ISEMAIL_IPV6BADCHAR'		, 145);
  112. 		define('ISEMAIL_IPV6TOOMANYGROUPS'	, 146);
  113. 		define('ISEMAIL_DOMAINEMPTYELEMENT'	, 147);
  114. 		define('ISEMAIL_DOMAINELEMENTTOOLONG'	, 148);
  115. 		define('ISEMAIL_DOMAINBADCHAR'		, 149);
  116. 		define('ISEMAIL_DOMAINTOOLONG'		, 150);
  117. 		define('ISEMAIL_IPV6SINGLECOLONSTART'	, 151);
  118. 		define('ISEMAIL_IPV6SINGLECOLONEND'	, 152);
  119. 		// Unexpected errors
  120. //		define('ISEMAIL_BADPARAMETER'		, 190);
  121. //		define('ISEMAIL_NOTDEFINED'		, 191);
  122. // revision 2.1: Redefined unexpected error constants so they don't clash with the ISEMAIL_WARNING bit
  123. // revision 2.5: Undefined unused constants
  124. 	}
  125.  
  126. 	if (is_bool($errorlevel)) {
  127. 		if ((bool) $errorlevel) {
  128. 			$diagnose	= true;
  129. 			$warn		= false;
  130. 		} else {
  131. 			$diagnose	= false;
  132. 			$warn		= false;
  133. 		}
  134. 	} else {
  135. 		switch ((int) $errorlevel) {
  136. 		case E_WARNING:
  137. 			$diagnose	= true;
  138. 			$warn		= true;
  139. 			break;
  140. 		case E_ERROR:
  141. 			$diagnose	= true;
  142. 			$warn		= false;
  143. 			break;
  144. 		default:
  145. 			$diagnose	= false;
  146. 			$warn		= false;
  147. 		}
  148. 	}
  149.  
  150. 	if ($diagnose) /*.mixed.*/ $return_status = ISEMAIL_VALID; else $return_status = true;
  151. // version 2.0: Enhance $diagnose parameter to $errorlevel
  152.  
  153. 	// the upper limit on address lengths should normally be considered to be 254
  154. 	// 	(http://www.rfc-editor.org/errata_search.php?rfc=3696)
  155. 	// 	NB My erratum has now been verified by the IETF so the correct answer is 254
  156. 	//
  157. 	// The maximum total length of a reverse-path or forward-path is 256
  158. 	// characters (including the punctuation and element separators)
  159. 	// 	(http://tools.ietf.org/html/rfc5321#section-4.5.3.1.3)
  160. 	//	NB There is a mandatory 2-character wrapper round the actual address
  161. 	$emailLength = strlen($email);
  162. // revision 1.17: Max length reduced to 254 (see above)
  163. 	if ($emailLength > 254)			if ($diagnose) return ISEMAIL_TOOLONG;		else return false;	// Too long
  164.  
  165. 	// Contemporary email addresses consist of a "local part" separated from
  166. 	// a "domain part" (a fully-qualified domain name) by an at-sign ("@").
  167. 	// 	(http://tools.ietf.org/html/rfc3696#section-3)
  168. 	$atIndex = strrpos($email,'@');
  169.  
  170. 	if ($atIndex === false)			if ($diagnose) return ISEMAIL_NOAT;		else return false;	// No at-sign
  171. 	if ($atIndex === 0)			if ($diagnose) return ISEMAIL_NOLOCALPART;	else return false;	// No local part
  172. 	if ($atIndex === $emailLength - 1)	if ($diagnose) return ISEMAIL_NODOMAIN;		else return false;	// No domain part
  173. // revision 1.14: Length test bug suggested by Andrew Campbell of Gloucester, MA
  174.  
  175. 	// Sanitize comments
  176. 	// - remove nested comments, quotes and dots in comments
  177. 	// - remove parentheses and dots from quoted strings
  178. 	$braceDepth	= 0;
  179. 	$inQuote	= false;
  180. 	$escapeThisChar	= false;
  181.  
  182. 	for ($i = 0; $i < $emailLength; ++$i) {
  183. 		$char = $email[$i];
  184. 		$replaceChar = false;
  185.  
  186. 		if ($char === '\') 	$escapeThisChar = !$escapeThisChar;			// Escape the next character?
  187. 		else {
  188. 			switch ($char) {
  189. 			case '(':
  190. 				if	($escapeThisChar)	$replaceChar	= true;
  191. 				else if	($inQuote)		$replaceChar	= true;
  192. 				else if	($braceDepth++ > 0)	$replaceChar	= true;		// Increment brace depth
  193.  
  194. 				break;
  195. 			case ')':
  196. 				if	($escapeThisChar)	$replaceChar	= true;
  197. 				else if	($inQuote)		$replaceChar	= true;
  198. 				else {
  199. 					if (--$braceDepth > 0)	$replaceChar	= true;		// Decrement brace depth
  200. 					if ($braceDepth < 0)	$braceDepth	= 0;
  201. 				}
  202.  
  203. 				break;
  204. 			case '"':
  205. 				if	($escapeThisChar)	$replaceChar	= true;
  206. 				else if ($braceDepth === 0)	$inQuote	= !$inQuote;	// Are we inside a quoted string?
  207. 				else				$replaceChar	= true;
  208.  
  209. 				break;
  210. 			case '.':
  211. 				if	($escapeThisChar)	$replaceChar	= true;		// Dots don't help us either
  212. 				else if	($braceDepth > 0)	$replaceChar	= true;
  213.  
  214. 				break;
  215. 			default:
  216. 			}
  217.  
  218. 			$escapeThisChar = false;
  219. //			if ($replaceChar) $email[$i] = 'x';					// Replace the offending character with something harmless
  220. // revision 1.12: Line above replaced because PHPLint doesn't like that syntax
  221. 			if ($replaceChar) $email = (string) substr_replace($email, 'x', $i, 1);	// Replace the offending character with something harmless
  222. 		}
  223. 	}
  224.  
  225. 	$localPart	= substr($email, 0, $atIndex);
  226. 	$domain		= substr($email, $atIndex + 1);
  227. 	$FWS		= "(?:(?:(?:[ \t]*(?:\r\n))?[ \t]+)|(?:[ \t]+(?:(?:\r\n)[ \t]+)*))";	// Folding white space
  228. 	$dotArray	= /*. (array[]) .*/ array();
  229.  
  230. 	// Let's check the local part for RFC compliance...
  231. 	//
  232. 	// local-part      =       dot-atom / quoted-string / obs-local-part
  233. 	// obs-local-part  =       word *("." word)
  234. 	// 	(http://tools.ietf.org/html/rfc5322#section-3.4.1)
  235. 	//
  236. 	// Problem: need to distinguish between "first.last" and "first"."last"
  237. 	// (i.e. one element or two). And I suck at regexes.
  238. 	$dotArray	= preg_split('/\.(?=(?:[^\"]*\"[^\"]*\")*(?![^\"]*\"))/m', $localPart);
  239. 	$partLength	= 0;
  240.  
  241. 	foreach ($dotArray as $arrayMember) {
  242. 		$element = (string) $arrayMember;
  243. 		// Remove any leading or trailing FWS
  244. 		$new_element = preg_replace("/^$FWS|$FWS$/", '', $element);
  245. 		if ($warn && ($element !== $new_element)) $return_status = ISEMAIL_FWS;	// FWS is unlikely in the real world
  246. 		$element = $new_element;
  247. // version 2.3: Warning condition added
  248. 		$elementLength	= strlen($element);
  249.  
  250. 		if ($elementLength === 0)								if ($diagnose) return ISEMAIL_ZEROLENGTHELEMENT;	else return false;	// Can't have empty element (consecutive dots or dots at the start or end)
  251. // revision 1.15: Speed up the test and get rid of "unitialized string offset" notices from PHP
  252.  
  253. 		// We need to remove any valid comments (i.e. those at the start or end of the element)
  254. 		if ($element[0] === '(') {
  255. 			if ($warn) $return_status = ISEMAIL_COMMENTS;	// Comments are unlikely in the real world
  256. // version 2.0: Warning condition added
  257. 			$indexBrace = strpos($element, ')');
  258. 			if ($indexBrace !== false) {
  259. 				if (preg_match('/(?<!\\)[\(\)]/', substr($element, 1, $indexBrace - 1)) > 0)
  260. 													if ($diagnose) return ISEMAIL_BADCOMMENT_START;		else return false;	// Illegal characters in comment
  261. 				$element	= substr($element, $indexBrace + 1, $elementLength - $indexBrace - 1);
  262. 				$elementLength	= strlen($element);
  263. 			}
  264. 		}
  265.  
  266. 		if ($element[$elementLength - 1] === ')') {
  267. 			if ($warn) $return_status = ISEMAIL_COMMENTS;	// Comments are unlikely in the real world
  268. // version 2.0: Warning condition added
  269. 			$indexBrace = strrpos($element, '(');
  270. 			if ($indexBrace !== false) {
  271. 				if (preg_match('/(?<!\\)(?:[\(\)])/', substr($element, $indexBrace + 1, $elementLength - $indexBrace - 2)) > 0)
  272. 													if ($diagnose) return ISEMAIL_BADCOMMENT_END;		else return false;	// Illegal characters in comment
  273. 				$element	= substr($element, 0, $indexBrace);
  274. 				$elementLength	= strlen($element);
  275. 			}
  276. 		}
  277.  
  278. 		// Remove any remaining leading or trailing FWS around the element (having removed any comments)
  279. 		$new_element = preg_replace("/^$FWS|$FWS$/", '', $element);
  280. 		if ($warn && ($element !== $new_element)) $return_status = ISEMAIL_FWS;	// FWS is unlikely in the real world
  281. 		$element = $new_element;
  282. // version 2.0: Warning condition added
  283.  
  284. 		// What's left counts towards the maximum length for this part
  285. 		if ($partLength > 0) $partLength++;	// for the dot
  286. 		$partLength += strlen($element);
  287.  
  288. 		// Each dot-delimited component can be an atom or a quoted string
  289. 		// (because of the obs-local-part provision)
  290. 		if (preg_match('/^"(?:.)*"$/s', $element) > 0) {
  291. 			// Quoted-string tests:
  292. 			if ($warn) $return_status = ISEMAIL_QUOTEDSTRING;	// Quoted string is unlikely in the real world
  293. // version 2.0: Warning condition added
  294. 			// Remove any FWS
  295. 			$element = preg_replace("/(?<!\\)$FWS/", '', $element);	// A warning condition, but we've already raised ISEMAIL_QUOTEDSTRING
  296. 			// My regex skillz aren't up to distinguishing between " \" \" \\" etc.
  297. 			// So remove all \ from the string first...
  298. 			$element = preg_replace('/\\\\/', ' ', $element);
  299. 			if (preg_match('/(?<!\\|^)["\r\n\x00](?!$)|\\"$|""/', $element) > 0)	if ($diagnose) return ISEMAIL_UNESCAPEDDELIM;		else return false;	// ", CR, LF and NUL must be escaped
  300. // version 2.0: allow ""@example.com because it's technically valid
  301. 		} else {
  302. 			// Unquoted string tests:
  303. 			//
  304. 			// Period (".") may...appear, but may not be used to start or end the
  305. 			// local part, nor may two or more consecutive periods appear.
  306. 			// 	(http://tools.ietf.org/html/rfc3696#section-3)
  307. 			//
  308. 			// A zero-length element implies a period at the beginning or end of the
  309. 			// local part, or two periods together. Either way it's not allowed.
  310. 			if ($element === '')								if ($diagnose) return ISEMAIL_EMPTYELEMENT;		else return false;	// Dots in wrong place
  311.  
  312. 			// Any ASCII graphic (printing) character other than the
  313. 			// at-sign ("@"), backslash, double quote, comma, or square brackets may
  314. 			// appear without quoting.  If any of that list of excluded characters
  315. 			// are to appear, they must be quoted
  316. 			// 	(http://tools.ietf.org/html/rfc3696#section-3)
  317. 			//
  318. 			// Any excluded characters? i.e. 0x00-0x20, (, ), <, >, [, ], :, ;, @, , comma, period, "
  319. 			if (preg_match('/[\x00-\x20\(\)<>\[\]:;@\\,\."]/', $element) > 0)	if ($diagnose) return ISEMAIL_UNESCAPEDSPECIAL;		else return false;	// These characters must be in a quoted string
  320. 			if ($warn && (preg_match('/^\w+/', $element) === 0)) $return_status = ISEMAIL_UNLIKELYINITIAL;	// First character is an odd one
  321. 		}
  322. 	}
  323.  
  324. 	if ($partLength > 64)										if ($diagnose) return ISEMAIL_LOCALTOOLONG;		else return false;	// Local part must be 64 characters or less
  325.  
  326. 	// Now let's check the domain part...
  327.  
  328. 	// The domain name can also be replaced by an IP address in square brackets
  329. 	// 	(http://tools.ietf.org/html/rfc3696#section-3)
  330. 	// 	(http://tools.ietf.org/html/rfc5321#section-4.1.3)
  331. 	// 	(http://tools.ietf.org/html/rfc4291#section-2.2)
  332. 	if (preg_match('/^\[(.)+]$/', $domain) === 1) {
  333. 		// It's an address-literal
  334. 		if ($warn) $return_status = ISEMAIL_ADDRESSLITERAL;	// Quoted string is unlikely in the real world
  335. // version 2.0: Warning condition added
  336. 		$addressLiteral = substr($domain, 1, strlen($domain) - 2);
  337. 		$groupMax	= 8;
  338. // revision 2.1: new IPv6 testing strategy
  339. 		$matchesIP	= array();
  340. 		$colon		= ':';	// Revision 2.7: Daniel Marschall's new IPv6 testing strategy
  341. 		$double_colon	= '::';
  342.  
  343. 		// Extract IPv4 part from the end of the address-literal (if there is one)
  344. 		if (preg_match('/\b(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)$/', $addressLiteral, $matchesIP) > 0) {
  345. 			$index = strrpos($addressLiteral, $matchesIP[0]);
  346.  
  347. 			if ($index === 0) {
  348. 				// Nothing there except a valid IPv4 address, so...
  349. 				if ($diagnose) return $return_status; else return true;
  350. // version 2.0: return warning if one is set
  351. 			} else {
  352. //-				// Assume it's an attempt at a mixed address (IPv6 + IPv4)
  353. //-				if ($addressLiteral[$index - 1] !== $colon)				if ($diagnose) return ISEMAIL_IPV4BADPREFIX;		else return false;	// Character preceding IPv4 address must be ':'
  354. // revision 2.1: new IPv6 testing strategy
  355. 				if (substr($addressLiteral, 0, 5) !== 'IPv6:')				if ($diagnose) return ISEMAIL_IPV6BADPREFIXMIXED;	else return false;	// RFC5321 section 4.1.3
  356. //-
  357. //-				$IPv6		= substr($addressLiteral, 5, ($index === 7) ? 2 : $index - 6);
  358. //-				$groupMax	= 6;
  359. // revision 2.1: new IPv6 testing strategy
  360. 				$IPv6		= substr($addressLiteral, 5, $index - 5) . '0000:0000'; // Convert IPv4 part to IPv6 format
  361. 			}
  362. 		} else {
  363. 			// It must be an attempt at pure IPv6
  364. 			if (substr($addressLiteral, 0, 5) !== 'IPv6:')					if ($diagnose) return ISEMAIL_IPV6BADPREFIX;		else return false;	// RFC5321 section 4.1.3
  365. 			$IPv6 = substr($addressLiteral, 5);
  366. //-			$groupMax = 8;
  367. // revision 2.1: new IPv6 testing strategy
  368. 		}
  369.  
  370. 		$matchesIP	= explode($colon, $IPv6);	// Revision 2.7: Daniel Marschall's new IPv6 testing strategy
  371. 		$groupCount	= count($matchesIP);
  372. 		$index		= strpos($IPv6,$double_colon);
  373.  
  374. 		if ($index === false) {
  375. 			// We need exactly the right number of groups
  376. 			if ($groupCount !== $groupMax)							if ($diagnose) return ISEMAIL_IPV6GROUPCOUNT;		else return false;	// RFC5321 section 4.1.3
  377. 		} else {
  378. 			if ($index !== strrpos($IPv6,$double_colon))					if ($diagnose) return ISEMAIL_IPV6DOUBLEDOUBLECOLON;	else return false;	// More than one '::'
  379. 			if ($index === 0 || $index === (strlen($IPv6) - 2)) $groupMax++;	// RFC 4291 allows :: at the start or end of an address with 7 other groups in addition
  380. 			if ($groupCount > $groupMax)							if ($diagnose) return ISEMAIL_IPV6TOOMANYGROUPS;	else return false;	// Too many IPv6 groups in address
  381. 			if ($groupCount === $groupMax) $return_status = ISEMAIL_SINGLEGROUPELISION;	// Eliding a single group with :: is deprecated by RFCs 5321 & 5952
  382. 		}
  383.  
  384. 		// Check for single : at start and end of address
  385. 		// Revision 2.7: Daniel Marschall's new IPv6 testing strategy
  386. 		if ((substr($IPv6, 0,  1)	=== $colon) && (substr($IPv6, 1,  1) !== $colon))	if ($diagnose) return ISEMAIL_IPV6SINGLECOLONSTART;	else return false;	// Address starts with a single colon
  387. 		if ((substr($IPv6, -1)		=== $colon) && (substr($IPv6, -2, 1) !== $colon))	if ($diagnose) return ISEMAIL_IPV6SINGLECOLONEND;	else return false;	// Address ends with a single colon
  388.  
  389. 		// Check for unmatched characters
  390. 		if (count(preg_grep('/^[0-9A-Fa-f]{0,4}$/', $matchesIP, PREG_GREP_INVERT)) !== 0)	if ($diagnose) return ISEMAIL_IPV6BADCHAR	;	else return false;	// Illegal characters in address
  391. 		// It's a valid IPv6 address, so...
  392. 		if ($diagnose) return $return_status; else return true;
  393. // revision 2.1: bug fix: now correctly return warning status
  394. 	} else {
  395. 		// It's a domain name...
  396.  
  397. 		// The syntax of a legal Internet host name was specified in RFC-952
  398. 		// One aspect of host name syntax is hereby changed: the
  399. 		// restriction on the first character is relaxed to allow either a
  400. 		// letter or a digit.
  401. 		// 	(http://tools.ietf.org/html/rfc1123#section-2.1)
  402. 		//
  403. 		// NB RFC 1123 updates RFC 1035, but this is not currently apparent from reading RFC 1035.
  404. 		//
  405. 		// Most common applications, including email and the Web, will generally not
  406. 		// permit...escaped strings
  407. 		// 	(http://tools.ietf.org/html/rfc3696#section-2)
  408. 		//
  409. 		// the better strategy has now become to make the "at least one period" test,
  410. 		// to verify LDH conformance (including verification that the apparent TLD name
  411. 		// is not all-numeric)
  412. 		// 	(http://tools.ietf.org/html/rfc3696#section-2)
  413. 		//
  414. 		// Characters outside the set of alphabetic characters, digits, and hyphen MUST NOT appear in domain name
  415. 		// labels for SMTP clients or servers
  416. 		// 	(http://tools.ietf.org/html/rfc5321#section-4.1.2)
  417. 		//
  418. 		// RFC5321 precludes the use of a trailing dot in a domain name for SMTP purposes
  419. 		// 	(http://tools.ietf.org/html/rfc5321#section-4.1.2)
  420. 		$dotArray	= preg_split('/\.(?=(?:[^\"]*\"[^\"]*\")*(?![^\"]*\"))/m', $domain);
  421. 		$partLength	= 0;
  422. 		$element	= ''; // Since we use $element after the foreach loop let's make sure it has a value
  423. // revision 1.13: Line above added because PHPLint now checks for Definitely Assigned Variables
  424.  
  425. 		if ($warn && (count($dotArray) === 1))	$return_status = ISEMAIL_TLD;	// The mail host probably isn't a TLD
  426. // version 2.0: downgraded to a warning
  427.  
  428. 		foreach ($dotArray as $arrayMember) {
  429. 			$element = (string) $arrayMember;
  430. 			// Remove any leading or trailing FWS
  431. 			$new_element	= preg_replace("/^$FWS|$FWS$/", '', $element);
  432. 			if ($warn && ($element !== $new_element)) $return_status = ISEMAIL_FWS;	// FWS is unlikely in the real world
  433. 			$element = $new_element;
  434. // version 2.0: Warning condition added
  435. 			$elementLength	= strlen($element);
  436.  
  437. 			// Each dot-delimited component must be of type atext
  438. 			// A zero-length element implies a period at the beginning or end of the
  439. 			// local part, or two periods together. Either way it's not allowed.
  440. 			if ($elementLength === 0)							if ($diagnose) return ISEMAIL_DOMAINEMPTYELEMENT;	else return false;	// Dots in wrong place
  441. // revision 1.15: Speed up the test and get rid of "unitialized string offset" notices from PHP
  442.  
  443. 			// Then we need to remove all valid comments (i.e. those at the start or end of the element
  444. 			if ($element[0] === '(') {
  445. 				if ($warn) $return_status = ISEMAIL_COMMENTS;	// Comments are unlikely in the real world
  446. // version 2.0: Warning condition added
  447. 				$indexBrace = strpos($element, ')');
  448. 				if ($indexBrace !== false) {
  449. 					if (preg_match('/(?<!\\)[\(\)]/', substr($element, 1, $indexBrace - 1)) > 0)
  450. 													if ($diagnose) return ISEMAIL_BADCOMMENT_START;		else return false;	// Illegal characters in comment
  451. // revision 1.17: Fixed name of constant (also spotted by turboflash - thanks!)
  452. 					$element	= substr($element, $indexBrace + 1, $elementLength - $indexBrace - 1);
  453. 					$elementLength	= strlen($element);
  454. 				}
  455. 			}
  456.  
  457. 			if ($element[$elementLength - 1] === ')') {
  458. 				if ($warn) $return_status = ISEMAIL_COMMENTS;	// Comments are unlikely in the real world
  459. // version 2.0: Warning condition added
  460. 				$indexBrace = strrpos($element, '(');
  461. 				if ($indexBrace !== false) {
  462. 					if (preg_match('/(?<!\\)(?:[\(\)])/', substr($element, $indexBrace + 1, $elementLength - $indexBrace - 2)) > 0)
  463. 													if ($diagnose) return ISEMAIL_BADCOMMENT_END;		else return false;	// Illegal characters in comment
  464. // revision 1.17: Fixed name of constant (also spotted by turboflash - thanks!)
  465. 					$element	= substr($element, 0, $indexBrace);
  466. 					$elementLength	= strlen($element);
  467. 				}
  468. 			}
  469.  
  470. 			// Remove any leading or trailing FWS around the element (inside any comments)
  471. 			$new_element	= preg_replace("/^$FWS|$FWS$/", '', $element);
  472. 			if ($warn && ($element !== $new_element)) $return_status = ISEMAIL_FWS;	// FWS is unlikely in the real world
  473. 			$element = $new_element;
  474. // version 2.0: Warning condition added
  475.  
  476. 			// What's left counts towards the maximum length for this part
  477. 			if ($partLength > 0) $partLength++;	// for the dot
  478. 			$partLength += strlen($element);
  479.  
  480. 			// The DNS defines domain name syntax very generally -- a
  481. 			// string of labels each containing up to 63 8-bit octets,
  482. 			// separated by dots, and with a maximum total of 255
  483. 			// octets.
  484. 			// 	(http://tools.ietf.org/html/rfc1123#section-6.1.3.5)
  485. 			if ($elementLength > 63)							if ($diagnose) return ISEMAIL_DOMAINELEMENTTOOLONG;	else return false;	// Label must be 63 characters or less
  486.  
  487. 			// Any ASCII graphic (printing) character other than the
  488. 			// at-sign ("@"), backslash, double quote, comma, or square brackets may
  489. 			// appear without quoting.  If any of that list of excluded characters
  490. 			// are to appear, they must be quoted
  491. 			// 	(http://tools.ietf.org/html/rfc3696#section-3)
  492. 			//
  493. 			// If the hyphen is used, it is not permitted to appear at
  494. 			// either the beginning or end of a label.
  495. 			// 	(http://tools.ietf.org/html/rfc3696#section-2)
  496. 			//
  497. 			// Any excluded characters? i.e. 0x00-0x20, (, ), <, >, [, ], :, ;, @, , comma, period, "
  498. 			if (preg_match('/[\x00-\x20\(\)<>\[\]:;@\\,\."]|^-|-$/', $element) > 0) if ($diagnose) return ISEMAIL_DOMAINBADCHAR;		else return false;	// Illegal character in domain name
  499. 		}
  500.  
  501. 		if ($partLength > 255) 									if ($diagnose) return ISEMAIL_DOMAINTOOLONG;		else return false;	// Domain part must be 255 characters or less (http://tools.ietf.org/html/rfc1123#section-6.1.3.5)
  502.  
  503. 		if ($warn && (preg_match('/^[0-9]+$/', $element) > 0))	$return_status = ISEMAIL_TLDNUMERIC;	// TLD probably isn't all-numeric (http://www.apps.ietf.org/rfc/rfc3696.html#sec-2)
  504. // version 2.0: Downgraded to a warning
  505.  
  506. 		// Check DNS?
  507. 		if ($diagnose && ($return_status === ISEMAIL_VALID) && $checkDNS && function_exists('checkdnsrr')) {
  508. 			if (!(checkdnsrr($domain, 'A')))	$return_status = ISEMAIL_DOMAINNOTFOUND;	// 'A' record for domain can't be found
  509. 			if (!(checkdnsrr($domain, 'MX')))	$return_status = ISEMAIL_MXNOTFOUND;		// 'MX' record for domain can't be found
  510. 		}
  511. 	}
  512.  
  513. 	// Eliminate all other factors, and the one which remains must be the truth.
  514. 	// 	(Sherlock Holmes, The Sign of Four)
  515. 	if ($diagnose) return $return_status; else return true;
  516. // version 2.0: return warning if one is set
  517. }
  518.  
  519. $email = '[email protected]';
  520.  
  521. echo "Testing $email<br/>";
  522. echo "$email is " . ((is_email($email)) ? '' : 'not ') . 'a valid email address';
  523. ?>

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