<?php
// File name:	email.inc.php
// Description:	PHP subroutines for e-mail processing
// Date:	2004-02-11
// Author:	imacat <imacat@pristine.com.tw>
// Copyright:	Copyright (C) 2004-2007 Pristine Communications

// Set the include path
if (!defined("INCPATH_SET")) {
    require_once dirname(__FILE__) . "/incpath.inc.php";
}
// Referenced subroutines
require_once "monica/rfc822.inc.php";

// Settings
define("ISEMAIL_OK", "ok");
define("ISEMAIL_MALFORMED", "malformed");
define("ISEMAIL_DOMAIN_NOT_FOUND", "baddomain");
define("ISEMAIL_PATTERN",
    "/^" . RFC822_LOCAL_PART . "@(" . RFC822_DOMAIN . ")$/");

// is_email: Check the e-mail address validity
function is_email($email)
{
    // Malformed
    if (!preg_match(ISEMAIL_PATTERN, $email, $m)) {
        return ISEMAIL_MALFORMED;
    }
    $domain = $m[1];
    // Domain does not exists
    if (!_email_is_domain_exists($domain)) {
        return ISEMAIL_DOMAIN_NOT_FOUND;
    }
    return ISEMAIL_OK;
}

// is_email_wellformed: Check the e-mail address format validity
function is_email_wellformed($email)
{
    return preg_match(ISEMAIL_PATTERN, $email)? true: false;
}

// cmp_email: Compare 2 e-mails, to be used with usort()
function cmp_email($a, $b)
{
    static $rev = array();
    if (!array_key_exists($a, $rev)) {
        $rev[$a] = _email_rev_email($a);
    }
    if (!array_key_exists($b, $rev)) {
        $rev[$b] = _email_rev_email($b);
    }
    return strcmp($rev[$a], $rev[$b]);
}

// _email_is_domain_exists: Check the domain of an e-mail address
function _email_is_domain_exists($domain)
{
    // Cache the result
    static $cache = array();
    // Return the cache
    if (array_key_exists($domain, $cache)) {
        return $cache[$domain];
    }
    // Check the MX records
    if (getmxrr($domain, $mxhosts)) {
        $cache[$domain] = true;
        return $cache[$domain];
    }
    // Check the A or CNAME records
    if (gethostbynamel($domain) !== false) {
        $cache[$domain] = true;
        return $cache[$domain];
    }
    // Not found at last
    $cache[$domain] = false;
    return $cache[$domain];
}

// _email_rev_email: Reverse each part of an e-mail
function _email_rev_email($email)
{
    $pos = strpos($email, "@");
    $local = substr($email, 0, $pos);
    $domparts = explode(".", substr($email, $pos+1));
    return strtolower(implode(".", array_reverse($domparts)) . "@" . $local);
}

?>