CI的valid_email不够完善,重载

使用一下,发现它超过300个还认为是合法,起码长度不做检查:
换成另一位写的超长的检测:
application\helpers\MY_email_helper.php
-----------
<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed');

/*
*重写email,因为自带不够完善
Copyright 2009 Dominic Sayers
dominic_sayers@hotmail.com http://www.dominicsayers.com
Version 0.8

This source file is subject to the Common Public Attribution License Version 1.0 (CPAL) license.
The license terms are available through the world-wide-web at http://www.opensource.org/licenses/cpal_1.0 */
function valid_email ($email, $checkDNS = false) {
// Check that $email is a valid address
// (http://tools.ietf.org/html/rfc3696)
// (http://tools.ietf.org/html/rfc2822)
// (http://tools.ietf.org/html/rfc5322#section-3.4.1)
// (http://tools.ietf.org/html/rfc5321#section-4.1.3)
// (http://tools.ietf.org/html/rfc4291#section-2.2)
// (http://tools.ietf.org/html/rfc1123#section-2.1)

// the upper limit on address lengths should normally be considered to be 256
// (http://www.rfc-editor.org/errata_search.php?rfc=3696)
if (strlen($email) > 256) return false; // Too long

// Contemporary email addresses consist of a "local part" separated from
// a "domain part" (a fully-qualified domain name) by an at-sign ("@").
// (http://tools.ietf.org/html/rfc3696#section-3)
$index = strrpos($email,'@');

if ($index === false) return false; // No at-sign
if ($index === 0) return false; // No local part
if ($index > 64) return false; // Local part too long

$localPart = substr($email, 0, $index);
$domain = substr($email, $index + 1);
$domainLength = strlen($domain);

if ($domainLength === 0) return false; // No domain part
if ($domainLength > 255) return false; // Domain part too long

// Let's check the local part for RFC compliance...
//
// Any ASCII graphic (printing) character other than the
// at-sign ("@"), backslash, double quote, comma, or square brackets may
// appear without quoting. If any of that list of excluded characters
// are to appear, they must be quoted
// (http://tools.ietf.org/html/rfc3696#section-3)
if (preg_match('/^"(?:.)*"$/', $localPart) > 0) {
// Quoted-string tests:
//
// Note that since quoted-pair
// is allowed in a quoted-string, the quote and backslash characters may
// appear in a quoted-string so long as they appear as a quoted-pair.
// (http://tools.ietf.org/html/rfc2822#section-3.2.5)
$groupCount = preg_match_all('/(?:^"|"$|\\\\\\\\|\\\\")|(\\\\|")/', $localPart, $matches);
array_multisort($matches[1], SORT_DESC);
if ($matches[1][0] !== '') return false; // Unescaped quote or backslash character inside quoted string
if (preg_match('/^"\\\\*"$/', $localPart) > 0) return false; // "" and "\" are slipping through - must tidy this up
} else {
// Unquoted string tests:
//
// Period (".") may...appear, but may not be used to start or end the
// local part, nor may two or more consecutive periods appear.
// (http://tools.ietf.org/html/rfc3696#section-3)
if (preg_match('/^\\.|\\.\\.|\\.$/', $localPart) > 0) return false; // Dots in wrong place

// Any excluded characters? i.e. <space>, @, [, ], \, ", <comma>
if (preg_match('/[ @\\[\\]\\\\",]/', $localPart) > 0)
// Check all excluded characters are escaped
$stripped = '';//必须初始化,否则严格检测下面二句会出错;
$stripped = preg_replace('/\\\\[ @\\[\\]\\\\",]/', '', $localPart);
if (preg_match('/[ @\\[\\]\\\\",]/', $stripped) > 0) return false; // Unquoted excluded characters
}

// Now let's check the domain part...

// The domain name can also be replaced by an IP address in square brackets
// (http://tools.ietf.org/html/rfc3696#section-3)
// (http://tools.ietf.org/html/rfc5321#section-4.1.3)
// (http://tools.ietf.org/html/rfc4291#section-2.2)
if (preg_match('/^\\[(.)+]$/', $domain) === 1) {
// It's an address-literal
$addressLiteral = substr($domain, 1, $domainLength - 2);
$matchesIP = array();

// Extract IPv4 part from the end of the address-literal (if there is one)
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) {
$index = strrpos($addressLiteral, $matchesIP[0]);

if ($index === 0) {
// Nothing there except a valid IPv4 address, so...
return true;
} else {
// Assume it's an attempt at a mixed address (IPv6 + IPv4)
if ($addressLiteral[$index - 1] !== ':') return false; // Character preceding IPv4 address must be ':'
if (substr($addressLiteral, 0, 5) !== 'IPv6:') return false; // RFC5321 section 4.1.3

$IPv6 = substr($addressLiteral, 5, ($index ===7) ? 2 : $index - 6);
$groupMax = 6;
}
} else {
// It must be an attempt at pure IPv6
if (substr($addressLiteral, 0, 5) !== 'IPv6:') return false; // RFC5321 section 4.1.3
$IPv6 = substr($addressLiteral, 5);
$groupMax = 8;
}

$groupCount = preg_match_all('/^[0-9a-fA-F]{0,4}|\\:[0-9a-fA-F]{0,4}|(.)/', $IPv6, $matchesIP);
$index = strpos($IPv6,'::');

if ($index === false) {
// We need exactly the right number of groups
if ($groupCount !== $groupMax) return false; // RFC5321 section 4.1.3
} else {
if ($index !== strrpos($IPv6,'::')) return false; // More than one '::'
$groupMax = ($index === 0 || $index === (strlen($IPv6) - 2)) ? $groupMax : $groupMax - 1;
if ($groupCount > $groupMax) return false; // Too many IPv6 groups in address
}

// Check for unmatched characters
array_multisort($matchesIP
[1], SORT_DESC);
if ($matchesIP[1][0] !== '') return false; // Illegal characters in address

// It's a valid IPv6 address, so...
return true;
} else {
// It's a domain name...

// The syntax of a legal Internet host name was specified in RFC-952
// One aspect of host name syntax is hereby changed: the
// restriction on the first character is relaxed to allow either a
// letter or a digit.
// (http://tools.ietf.org/html/rfc1123#section-2.1)
//
// NB RFC 1123 updates RFC 1035, but this is not currently apparent from reading RFC 1035.
//
// Most common applications, including email and the Web, will generally not permit...escaped strings
// (http://tools.ietf.org/html/rfc3696#section-2)
//
// Characters outside the set of alphabetic characters, digits, and hyphen MUST NOT appear in domain name
// labels for SMTP clients or servers
// (http://tools.ietf.org/html/rfc5321#section-4.1.2)
//
// RFC5321 precludes the use of a trailing dot in a domain name for SMTP purposes
// (http://tools.ietf.org/html/rfc5321#section-4.1.2)
$matches = array();
$groupCount = preg_match_all('/(?:[0-9a-zA-Z][0-9a-zA-Z-]{0,61}[0-9a-zA-Z]|[a-zA-Z])(?:\\.|$)|(.)/', $domain, $matches);
$level = count($matches[0]);

if ($level == 1) return false; // Mail host can't be a TLD

$TLD = $matches[0][$level - 1];
if (substr($TLD, strlen($TLD) - 1, 1) === '.') return false; // TLD can't end in a dot
if (preg_match('/^[0-9]+$/', $TLD) > 0) return false; // TLD can't be all-numeric

// Check for unmatched characters
array_multisort($matches[1], SORT_DESC);
if ($matches[1][0] !== '') return false; // Illegal characters in domain, or label longer than 63 characters

// Check DNS?
if ($checkDNS && function_exists('checkdnsrr')) {
if (!(checkdnsrr($domain, 'A') || checkdnsrr($domain, 'MX'))) {
return false; // Domain doesn't actually exist
}
}

// Eliminate all other factors, and the one which remains must be the truth.
// (Sherlock Holmes, The Sign of Four)
return true;
}
}