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<?php

// +-----------------------------------------------------------------------+

// | Copyright (c) 2001-2002, Richard Heyes                                |

// | All rights reserved.                                                  |

// |                                                                       |

// | Redistribution and use in source and binary forms, with or without    |

// | modification, are permitted provided that the following conditions    |

// | are met:                                                              |

// |                                                                       |

// | o Redistributions of source code must retain the above copyright      |

// |   notice, this list of conditions and the following disclaimer.       |

// | o Redistributions in binary form must reproduce the above copyright   |

// |   notice, this list of conditions and the following disclaimer in the |

// |   documentation and/or other materials provided with the distribution.|

// | o The names of the authors may not be used to endorse or promote      |

// |   products derived from this software without specific prior written  |

// |   permission.                                                         |

// |                                                                       |

// | THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS   |

// | "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT     |

// | LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |

// | A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT  |

// | OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |

// | SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT      |

// | LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |

// | DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |

// | THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT   |

// | (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |

// | OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.  |

// |                                                                       |

// +-----------------------------------------------------------------------+

// | Authors: Richard Heyes <richard@phpguru.org>                          |

// |          Chuck Hagenbuch <chuck@horde.org>                            |

// +-----------------------------------------------------------------------+

/**

 * RFC 822 Email address list validation Utility

 *

 * What is it?

 *

 * This class will take an address string, and parse it into it's consituent

 * parts, be that either addresses, groups, or combinations. Nested groups

 * are not supported. The structure it returns is pretty straight forward,

 * and is similar to that provided by the imap_rfc822_parse_adrlist(). Use

 * print_r() to view the structure.

 *

 * How do I use it?

 *

 * $address_string = 'My Group: "Richard" <richard@localhost> (A comment), ted@example.com (Ted Bloggs), Barney;';

 * $structure = Mail_RFC822::parseAddressList($address_string, 'example.com', true)

 * print_r($structure);

 *

 * @author  Richard Heyes <richard@phpguru.org>

 * @author  Chuck Hagenbuch <chuck@horde.org>

 * @version $Revision: 1.1 $

 * @license BSD

 * @package Mail

 */

class Mail_RFC822 {

    /**

     * The address being parsed by the RFC822 object.

     * @var string $address

     */

    var $address = '';

    /**

     * The default domain to use for unqualified addresses.

     * @var string $default_domain

     */

    var $default_domain = 'localhost';

    /**

     * Should we return a nested array showing groups, or flatten everything?

     * @var boolean $nestGroups

     */

    var $nestGroups = true;

    /**

     * Whether or not to validate atoms for non-ascii characters.

     * @var boolean $validate

     */

    var $validate = true;

    /**

     * The array of raw addresses built up as we parse.

     * @var array $addresses

     */

    var $addresses = array();

    /**

     * The final array of parsed address information that we build up.

     * @var array $structure

     */

    var $structure = array();

    /**

     * The current error message, if any.

     * @var string $error

     */

    var $error = null;

    /**

     * An internal counter/pointer.

     * @var integer $index

     */

    var $index = null;

    /**

     * The number of groups that have been found in the address list.

     * @var integer $num_groups

     * @access public

     */

    var $num_groups = 0;

    /**

     * A variable so that we can tell whether or not we're inside a

     * Mail_RFC822 object.

     * @var boolean $mailRFC822

     */

    var $mailRFC822 = true;

    /**

    * A limit after which processing stops

    * @var int $limit

    */

    var $limit = null;

    /**

     * Sets up the object. The address must either be set here or when

     * calling parseAddressList(). One or the other.

     *

     * @access public

     * @param string  $address         The address(es) to validate.

     * @param string  $default_domain  Default domain/host etc. If not supplied, will be set to localhost.

     * @param boolean $nest_groups     Whether to return the structure with groups nested for easier viewing.

     * @param boolean $validate        Whether to validate atoms. Turn this off if you need to run addresses through before encoding the personal names, for instance.

     *

     * @return object Mail_RFC822 A new Mail_RFC822 object.

     */

    function Mail_RFC822($address = null, $default_domain = null, $nest_groups = null, $validate = null, $limit = null)

    {

        if (isset($address))        $this->address        = $address;

        if (isset($default_domain)) $this->default_domain = $default_domain;

        if (isset($nest_groups))    $this->nestGroups     = $nest_groups;

        if (isset($validate))       $this->validate       = $validate;

        if (isset($limit))          $this->limit          = $limit;

    }

    /**

     * Starts the whole process. The address must either be set here

     * or when creating the object. One or the other.

     *

     * @access public

     * @param string  $address         The address(es) to validate.

     * @param string  $default_domain  Default domain/host etc.

     * @param boolean $nest_groups     Whether to return the structure with groups nested for easier viewing.

     * @param boolean $validate        Whether to validate atoms. Turn this off if you need to run addresses through before encoding the personal names, for instance.

     *

     * @return array A structured array of addresses.

     */

    function parseAddressList($address = null, $default_domain = null, $nest_groups = null, $validate = null, $limit = null)

    {

        if (!isset($this) || !isset($this->mailRFC822)) {

            $obj = new Mail_RFC822($address, $default_domain, $nest_groups, $validate, $limit);

            return $obj->parseAddressList();

        }

        if (isset($address))        $this->address        = $address;

        if (isset($default_domain)) $this->default_domain = $default_domain;

        if (isset($nest_groups))    $this->nestGroups     = $nest_groups;

        if (isset($validate))       $this->validate       = $validate;

        if (isset($limit))          $this->limit          = $limit;

        $this->structure  = array();

        $this->addresses  = array();

        $this->error      = null;

        $this->index      = null;

        // Unfold any long lines in $this->address.

        $this->address = preg_replace('/\r?\n/', "\r\n", $this->address);

        $this->address = preg_replace('/\r\n(\t| )+/', ' ', $this->address);

        while ($this->address = $this->_splitAddresses($this->address));

        if ($this->address === false || isset($this->error)) {

            require_once 'PEAR.php';

            return PEAR::raiseError($this->error);

        }

        // Validate each address individually.  If we encounter an invalid

        // address, stop iterating and return an error immediately.

        foreach ($this->addresses as $address) {

            $valid = $this->_validateAddress($address);

            if ($valid === false || isset($this->error)) {

                require_once 'PEAR.php';

                return PEAR::raiseError($this->error);

            }

            if (!$this->nestGroups) {

                $this->structure = array_merge($this->structure, $valid);

            } else {

                $this->structure[] = $valid;

            }

        }

        return $this->structure;

    }

    /**

     * Splits an address into separate addresses.

     *

     * @access private

     * @param string $address The addresses to split.

     * @return boolean Success or failure.

     */

    function _splitAddresses($address)

    {

        if (!empty($this->limit) && count($this->addresses) == $this->limit) {

            return '';

        }

        if ($this->_isGroup($address) && !isset($this->error)) {

            $split_char = ';';

            $is_group   = true;

        } elseif (!isset($this->error)) {

            $split_char = ',';

            $is_group   = false;

        } elseif (isset($this->error)) {

            return false;

        }

        // Split the string based on the above ten or so lines.

        $parts  = explode($split_char, $address);

        $string = $this->_splitCheck($parts, $split_char);

        // If a group...

        if ($is_group) {

            // If $string does not contain a colon outside of

            // brackets/quotes etc then something's fubar.

            // First check there's a colon at all:

            if (strpos($string, ':') === false) {

                $this->error = 'Invalid address: ' . $string;

                return false;

            }

            // Now check it's outside of brackets/quotes:

            if (!$this->_splitCheck(explode(':', $string), ':')) {

                return false;

            }

            // We must have a group at this point, so increase the counter:

            $this->num_groups++;

        }

        // $string now contains the first full address/group.

        // Add to the addresses array.

        $this->addresses[] = array(

                                   'address' => trim($string),

                                   'group'   => $is_group

                                   );

        // Remove the now stored address from the initial line, the +1

        // is to account for the explode character.

        $address = trim(substr($address, strlen($string) + 1));

        // If the next char is a comma and this was a group, then

        // there are more addresses, otherwise, if there are any more

        // chars, then there is another address.

        if ($is_group && substr($address, 0, 1) == ','){

            $address = trim(substr($address, 1));

            return $address;

        } elseif (strlen($address) > 0) {

            return $address;

        } else {

            return '';

        }

        // If you got here then something's off

        return false;

    }

    /**

     * Checks for a group at the start of the string.

     *

     * @access private

     * @param string $address The address to check.

     * @return boolean Whether or not there is a group at the start of the string.

     */

    function _isGroup($address)

    {

        // First comma not in quotes, angles or escaped:

        $parts  = explode(',', $address);

        $string = $this->_splitCheck($parts, ',');

        // Now we have the first address, we can reliably check for a

        // group by searching for a colon that's not escaped or in

        // quotes or angle brackets.

        if (count($parts = explode(':', $string)) > 1) {

            $string2 = $this->_splitCheck($parts, ':');

            return ($string2 !== $string);

        } else {

            return false;

        }

    }

    /**

     * A common function that will check an exploded string.

     *

     * @access private

     * @param array $parts The exloded string.

     * @param string $char  The char that was exploded on.

     * @return mixed False if the string contains unclosed quotes/brackets, or the string on success.

     */

    function _splitCheck($parts, $char)

    {

        $string = $parts[0];

        for ($i = 0; $i < count($parts); $i++) {

            if ($this->_hasUnclosedQuotes($string)

                || $this->_hasUnclosedBrackets($string, '<>')

                || $this->_hasUnclosedBrackets($string, '[]')

                || $this->_hasUnclosedBrackets($string, '()')

                || substr($string, -1) == '\\') {

                if (isset($parts[$i + 1])) {

                    $string = $string . $char . $parts[$i + 1];

                } else {

                    $this->error = 'Invalid address spec. Unclosed bracket or quotes';

                    return false;

                }

            } else {

                $this->index = $i;

                break;

            }

        }

        return $string;

    }

    /**

     * Checks if a string has an unclosed quotes or not.

     *

     * @access private

     * @param string $string The string to check.

     * @return boolean True if there are unclosed quotes inside the string, false otherwise.

     */

    function _hasUnclosedQuotes($string)

    {

        $string     = explode('"', $string);

        $string_cnt = count($string);

        for ($i = 0; $i < (count($string) - 1); $i++)

            if (substr($string[$i], -1) == '\\')

                $string_cnt--;

        return ($string_cnt % 2 === 0);

    }

    /**

     * Checks if a string has an unclosed brackets or not. IMPORTANT:

     * This function handles both angle brackets and square brackets;

     *

     * @access private

     * @param string $string The string to check.

     * @param string $chars  The characters to check for.

     * @return boolean True if there are unclosed brackets inside the string, false otherwise.

     */

    function _hasUnclosedBrackets($string, $chars)

    {

        $num_angle_start = substr_count($string, $chars[0]);

        $num_angle_end   = substr_count($string, $chars[1]);

        $this->_hasUnclosedBracketsSub($string, $num_angle_start, $chars[0]);

        $this->_hasUnclosedBracketsSub($string, $num_angle_end, $chars[1]);

        if ($num_angle_start < $num_angle_end) {

            $this->error = 'Invalid address spec. Unmatched quote or bracket (' . $chars . ')';

            return false;

        } else {

            return ($num_angle_start > $num_angle_end);

        }

    }

    /**

     * Sub function that is used only by hasUnclosedBrackets().

     *

     * @access private

     * @param string $string The string to check.

     * @param integer &$num    The number of occurences.

     * @param string $char   The character to count.

     * @return integer The number of occurences of $char in $string, adjusted for backslashes.

     */

    function _hasUnclosedBracketsSub($string, &$num, $char)

    {

        $parts = explode($char, $string);

        for ($i = 0; $i < count($parts); $i++){

            if (substr($parts[$i], -1) == '\\' || $this->_hasUnclosedQuotes($parts[$i]))

                $num--;

            if (isset($parts[$i + 1]))

                $parts[$i + 1] = $parts[$i] . $char . $parts[$i + 1];

        }

        return $num;

    }

    /**

     * Function to begin checking the address.

     *

     * @access private

     * @param string $address The address to validate.

     * @return mixed False on failure, or a structured array of address information on success.

     */

    function _validateAddress($address)

    {

        $is_group = false;

        $addresses = array();

        if ($address['group']) {

            $is_group = true;

            // Get the group part of the name

            $parts     = explode(':', $address['address']);

            $groupname = $this->_splitCheck($parts, ':');

            $structure = array();

            // And validate the group part of the name.

            if (!$this->_validatePhrase($groupname)){

                $this->error = 'Group name did not validate.';

                return false;

            } else {

                // Don't include groups if we are not nesting

                // them. This avoids returning invalid addresses.

                if ($this->nestGroups) {

                    $structure = new stdClass;

                    $structure->groupname = $groupname;

                }

            }

            $address['address'] = ltrim(substr($address['address'], strlen($groupname . ':')));

        }

        // If a group then split on comma and put into an array.

        // Otherwise, Just put the whole address in an array.

        if ($is_group) {

            while (strlen($address['address']) > 0) {

                $parts       = explode(',', $address['address']);

                $addresses[] = $this->_splitCheck($parts, ',');

                $address['address'] = trim(substr($address['address'], strlen(end($addresses) . ',')));

            }

        } else {

            $addresses[] = $address['address'];

        }

        // Check that $addresses is set, if address like this:

        // Groupname:;

        // Then errors were appearing.

        if (!count($addresses)){

            $this->error = 'Empty group.';

            return false;

        }

        // Trim the whitespace from all of the address strings.

        array_map('trim', $addresses);

        // Validate each mailbox.

        // Format could be one of: name <geezer@domain.com>

        //                         geezer@domain.com

        //                         geezer

        // ... or any other format valid by RFC 822.

        for ($i = 0; $i < count($addresses); $i++) {

            if (!$this->validateMailbox($addresses[$i])) {

                if (empty($this->error)) {

                    $this->error = 'Validation failed for: ' . $addresses[$i];

                }

                return false;

            }

        }

        // Nested format

        if ($this->nestGroups) {

            if ($is_group) {

                $structure->addresses = $addresses;

            } else {

                $structure = $addresses[0];

            }

        // Flat format

        } else {

            if ($is_group) {

                $structure = array_merge($structure, $addresses);

            } else {

                $structure = $addresses;

            }

        }

        return $structure;

    }

    /**

     * Function to validate a phrase.

     *

     * @access private

     * @param string $phrase The phrase to check.

     * @return boolean Success or failure.

     */

    function _validatePhrase($phrase)

    {

        // Splits on one or more Tab or space.

        $parts = preg_split('/[ \\x09]+/', $phrase, -1, PREG_SPLIT_NO_EMPTY);

        $phrase_parts = array();

        while (count($parts) > 0){

            $phrase_parts[] = $this->_splitCheck($parts, ' ');

            for ($i = 0; $i < $this->index + 1; $i++)

                array_shift($parts);

        }

        foreach ($phrase_parts as $part) {

            // If quoted string:

            if (substr($part, 0, 1) == '"') {

                if (!$this->_validateQuotedString($part)) {

                    return false;

                }

                continue;

            }

            // Otherwise it's an atom:

            if (!$this->_validateAtom($part)) return false;

        }

        return true;

    }

    /**

     * Function to validate an atom which from rfc822 is:

     * atom = 1*<any CHAR except specials, SPACE and CTLs>

     *

     * If validation ($this->validate) has been turned off, then

     * validateAtom() doesn't actually check anything. This is so that you

     * can split a list of addresses up before encoding personal names

     * (umlauts, etc.), for example.

     *

     * @access private

     * @param string $atom The string to check.

     * @return boolean Success or failure.

     */

    function _validateAtom($atom)

    {

        if (!$this->validate) {

            // Validation has been turned off; assume the atom is okay.

            return true;

        }

        // Check for any char from ASCII 0 - ASCII 127

        if (!preg_match('/^[\\x00-\\x7E]+$/i', $atom, $matches)) {

            return false;

        }

        // Check for specials:

        if (preg_match('/[][()<>@,;\\:". ]/', $atom)) {

            return false;

        }

        // Check for control characters (ASCII 0-31):

        if (preg_match('/[\\x00-\\x1F]+/', $atom)) {

            return false;

        }

        return true;

    }

    /**

     * Function to validate quoted string, which is:

     * quoted-string = <"> *(qtext/quoted-pair) <">

     *

     * @access private

     * @param string $qstring The string to check

     * @return boolean Success or failure.

     */

    function _validateQuotedString($qstring)

    {

        // Leading and trailing "

        $qstring = substr($qstring, 1, -1);

        // Perform check, removing quoted characters first.

        return !preg_match('/[\x0D\\\\"]/', preg_replace('/\\\\./', '', $qstring));

    }

    /**

     * Function to validate a mailbox, which is:

     * mailbox =   addr-spec         ; simple address

     *           / phrase route-addr ; name and route-addr

     *

     * @access public

     * @param string &$mailbox The string to check.

     * @return boolean Success or failure.

     */

    function validateMailbox(&$mailbox)

    {

        // A couple of defaults.

        $phrase  = '';

        $comment = '';

        $comments = array();

        // Catch any RFC822 comments and store them separately.

        $_mailbox = $mailbox;

        while (strlen(trim($_mailbox)) > 0) {

            $parts = explode('(', $_mailbox);

            $before_comment = $this->_splitCheck($parts, '(');

            if ($before_comment != $_mailbox) {

                // First char should be a (.

                $comment    = substr(str_replace($before_comment, '', $_mailbox), 1);

                $parts      = explode(')', $comment);

                $comment    = $this->_splitCheck($parts, ')');

                $comments[] = $comment;

                // +1 is for the trailing )

                $_mailbox   = substr($_mailbox, strpos($_mailbox, $comment)+strlen($comment)+1);

            } else {

                break;

            }

        }

        foreach ($comments as $comment) {

            $mailbox = str_replace("($comment)", '', $mailbox);

        }

        $mailbox = trim($mailbox);

        // Check for name + route-addr

        if (substr($mailbox, -1) == '>' && substr($mailbox, 0, 1) != '<') {

            $parts  = explode('<', $mailbox);

            $name   = $this->_splitCheck($parts, '<');

            $phrase     = trim($name);

            $route_addr = trim(substr($mailbox, strlen($name.'<'), -1));

            if ($this->_validatePhrase($phrase) === false || ($route_addr = $this->_validateRouteAddr($route_addr)) === false) {

                return false;

            }

        // Only got addr-spec

        } else {

            // First snip angle brackets if present.

            if (substr($mailbox, 0, 1) == '<' && substr($mailbox, -1) == '>') {

                $addr_spec = substr($mailbox, 1, -1);

            } else {

                $addr_spec = $mailbox;

            }

            if (($addr_spec = $this->_validateAddrSpec($addr_spec)) === false) {

                return false;

            }

        }

        // Construct the object that will be returned.

        $mbox = new stdClass();

        // Add the phrase (even if empty) and comments

        $mbox->personal = $phrase;

        $mbox->comment  = isset($comments) ? $comments : array();

        if (isset($route_addr)) {

            $mbox->mailbox = $route_addr['local_part'];

            $mbox->host    = $route_addr['domain'];

            $route_addr['adl'] !== '' ? $mbox->adl = $route_addr['adl'] : '';

        } else {

            $mbox->mailbox = $addr_spec['local_part'];

            $mbox->host    = $addr_spec['domain'];

        }

        $mailbox = $mbox;

        return true;

    }

    /**

     * This function validates a route-addr which is:

     * route-addr = "<" [route] addr-spec ">"

     *

     * Angle brackets have already been removed at the point of

     * getting to this function.

     *

     * @access private

     * @param string $route_addr The string to check.

     * @return mixed False on failure, or an array containing validated address/route information on success.

     */

    function _validateRouteAddr($route_addr)

    {

        // Check for colon.

        if (strpos($route_addr, ':') !== false) {

            $parts = explode(':', $route_addr);

            $route = $this->_splitCheck($parts, ':');

        } else {

            $route = $route_addr;

        }

        // If $route is same as $route_addr then the colon was in

        // quotes or brackets or, of course, non existent.

        if ($route === $route_addr){

            unset($route);

            $addr_spec = $route_addr;

            if (($addr_spec = $this->_validateAddrSpec($addr_spec)) === false) {

                return false;

            }

        } else {

            // Validate route part.

            if (($route = $this->_validateRoute($route)) === false) {

                return false;

            }

            $addr_spec = substr($route_addr, strlen($route . ':'));

            // Validate addr-spec part.

            if (($addr_spec = $this->_validateAddrSpec($addr_spec)) === false) {

                return false;

            }

        }

        if (isset($route)) {

            $return['adl'] = $route;

        } else {

            $return['adl'] = '';

        }

        $return = array_merge($return, $addr_spec);

        return $return;

    }

    /**

     * Function to validate a route, which is:

     * route = 1#("@" domain) ":"

     *

     * @access private

     * @param string $route The string to check.

     * @return mixed False on failure, or the validated $route on success.

     */

    function _validateRoute($route)

    {

        // Split on comma.

        $domains = explode(',', trim($route));

        foreach ($domains as $domain) {

            $domain = str_replace('@', '', trim($domain));

            if (!$this->_validateDomain($domain)) return false;

        }

        return $route;

    }

    /**

     * Function to validate a domain, though this is not quite what

     * you expect of a strict internet domain.

     *

     * domain = sub-domain *("." sub-domain)

     *

     * @access private

     * @param string $domain The string to check.

     * @return mixed False on failure, or the validated domain on success.

     */

    function _validateDomain($domain)

    {

        // Note the different use of $subdomains and $sub_domains

        $subdomains = explode('.', $domain);

        while (count($subdomains) > 0) {

            $sub_domains[] = $this->_splitCheck($subdomains, '.');

            for ($i = 0; $i < $this->index + 1; $i++)

                array_shift($subdomains);

        }

        foreach ($sub_domains as $sub_domain) {

            if (!$this->_validateSubdomain(trim($sub_domain)))

                return false;

        }

        // Managed to get here, so return input.

        return $domain;

    }

    /**

     * Function to validate a subdomain:

     *   subdomain = domain-ref / domain-literal

     *

     * @access private

     * @param string $subdomain The string to check.

     * @return boolean Success or failure.

     */

    function _validateSubdomain($subdomain)

    {

        if (preg_match('|^\[(.*)]$|', $subdomain, $arr)){

            if (!$this->_validateDliteral($arr[1])) return false;

        } else {

            if (!$this->_validateAtom($subdomain)) return false;

        }

        // Got here, so return successful.

        return true;

    }

    /**

     * Function to validate a domain literal:

     *   domain-literal =  "[" *(dtext / quoted-pair) "]"

     *

     * @access private

     * @param string $dliteral The string to check.

     * @return boolean Success or failure.

     */

    function _validateDliteral($dliteral)

    {

        return !preg_match('/(.)[][\x0D\\\\]/', $dliteral, $matches) && $matches[1] != '\\';

    }

    /**

     * Function to validate an addr-spec.

     *

     * addr-spec = local-part "@" domain

     *

     * @access private

     * @param string $addr_spec The string to check.

     * @return mixed False on failure, or the validated addr-spec on success.

     */

    function _validateAddrSpec($addr_spec)

    {

        $addr_spec = trim($addr_spec);

        // Split on @ sign if there is one.

        if (strpos($addr_spec, '@') !== false) {

            $parts      = explode('@', $addr_spec);

            $local_part = $this->_splitCheck($parts, '@');

            $domain     = substr($addr_spec, strlen($local_part . '@'));

        // No @ sign so assume the default domain.

        } else {

            $local_part = $addr_spec;

            $domain     = $this->default_domain;

        }

        if (($local_part = $this->_validateLocalPart($local_part)) === false) return false;

        if (($domain     = $this->_validateDomain($domain)) === false) return false;

        // Got here so return successful.

        return array('local_part' => $local_part, 'domain' => $domain);

    }

    /**

     * Function to validate the local part of an address:

     *   local-part = word *("." word)

     *

     * @access private

     * @param string $local_part

     * @return mixed False on failure, or the validated local part on success.

     */

    function _validateLocalPart($local_part)

    {

        $parts = explode('.', $local_part);

        $words = array();

        // Split the local_part into words.

        while (count($parts) > 0){

            $words[] = $this->_splitCheck($parts, '.');

            for ($i = 0; $i < $this->index + 1; $i++) {

                array_shift($parts);

            }

        }

        // Validate each word.

        foreach ($words as $word) {

            // If this word contains an unquoted space, it is invalid. (6.2.4)

            if (strpos($word, ' ') && $word[0] !== '"')

            {

                return false;

            }

            if ($this->_validatePhrase(trim($word)) === false) return false;

        }

        // Managed to get here, so return the input.

        return $local_part;

    }

    /**

     * Returns an approximate count of how many addresses are in the

     * given string. This is APPROXIMATE as it only splits based on a

     * comma which has no preceding backslash. Could be useful as

     * large amounts of addresses will end up producing *large*

     * structures when used with parseAddressList().

     *

     * @param  string $data Addresses to count

     * @return int          Approximate count

     */

    function approximateCount($data)

    {

        return count(preg_split('/(?<!\\\\),/', $data));

    }

    /**

     * This is a email validating function separate to the rest of the

     * class. It simply validates whether an email is of the common

     * internet form: <user>@<domain>. This can be sufficient for most

     * people. Optional stricter mode can be utilised which restricts

     * mailbox characters allowed to alphanumeric, full stop, hyphen

     * and underscore.

     *

     * @param  string  $data   Address to check

     * @param  boolean $strict Optional stricter mode

     * @return mixed           False if it fails, an indexed array

     *                         username/domain if it matches

     */

    function isValidInetAddress($data, $strict = false)

    {

        $regex = $strict ? '/^([.0-9a-z_+-]+)@(([0-9a-z-]+\.)+[0-9a-z]{2,4})$/i' : '/^([*+!.&#$|\'\\%\/0-9a-z^_`{}=?~:-]+)@(([0-9a-z-]+\.)+[0-9a-z]{2,4})$/i';

        if (preg_match($regex, trim($data), $matches)) {

            return array($matches[1], $matches[2]);

        } else {

            return false;

        }

    }

}