planningalerts/docs/include/PEAR/Mail/mimeDecode.php

<?php
/* vim: set expandtab tabstop=4 shiftwidth=4 softtabstop=4: */
// +-----------------------------------------------------------------------+
// | Copyright (c) 2002-2003  Richard Heyes                                |
// | Copyright (c) 2003-2005  The PHP Group                                |
// | All rights reserved.                                                  |
// |                                                                       |
// | Redistribution and use in source and binary forms, with or without    |
// | modification, are permitted provided that the following conditions    |
// | are met:                                                              |
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// | 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.|
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// |   products derived from this software without specific prior written  |
// |   permission.                                                         |
// |                                                                       |
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// | "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT     |
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// |                                                                       |
// +-----------------------------------------------------------------------+
// | Author: Richard Heyes <richard@phpguru.org>                           |
// +-----------------------------------------------------------------------+

require_once 'PEAR.php';

/**
*  +----------------------------- IMPORTANT ------------------------------+
*  | Usage of this class compared to native php extensions such as        |
*  | mailparse or imap, is slow and may be feature deficient. If available|
*  | you are STRONGLY recommended to use the php extensions.              |
*  +----------------------------------------------------------------------+
*
* Mime Decoding class
*
* This class will parse a raw mime email and return
* the structure. Returned structure is similar to
* that returned by imap_fetchstructure().
*
* USAGE: (assume $input is your raw email)
*
* $decode = new Mail_mimeDecode($input, "\r\n");
* $structure = $decode->decode();
* print_r($structure);
*
* Or statically:
*
* $params['input'] = $input;
* $structure = Mail_mimeDecode::decode($params);
* print_r($structure);
*
* TODO:
*  o Implement multipart/appledouble
*  o UTF8: ???

		> 4. We have also found a solution for decoding the UTF-8 
		> headers. Therefore I made the following function:
		> 
		> function decode_utf8($txt) {
		> $trans=array("Å&#8216;"=>"õ","ű"=>"û","Å�"=>"Ã&#8226;","Å°"
		=>"Ã&#8250;");
		> $txt=strtr($txt,$trans);
		> return(utf8_decode($txt));
		> }
		> 
		> And I have inserted the following line to the class:
		> 
		> if (strtolower($charset)=="utf-8") $text=decode_utf8($text);
		> 
		> ... before the following one in the "_decodeHeader" function:
		> 
		> $input = str_replace($encoded, $text, $input);
		> 
		> This way from now on it can easily decode the UTF-8 headers too.

*
* @author  Richard Heyes <richard@phpguru.org>
* @version $Revision: 1.46 $
* @package Mail
*/
class Mail_mimeDecode extends PEAR
{
    /**
     * The raw email to decode
     * @var    string
     */
    var $_input;

    /**
     * The header part of the input
     * @var    string
     */
    var $_header;

    /**
     * The body part of the input
     * @var    string
     */
    var $_body;

    /**
     * If an error occurs, this is used to store the message
     * @var    string
     */
    var $_error;

    /**
     * Flag to determine whether to include bodies in the
     * returned object.
     * @var    boolean
     */
    var $_include_bodies;

    /**
     * Flag to determine whether to decode bodies
     * @var    boolean
     */
    var $_decode_bodies;

    /**
     * Flag to determine whether to decode headers
     * @var    boolean
     */
    var $_decode_headers;

    /**
     * Constructor.
     *
     * Sets up the object, initialise the variables, and splits and
     * stores the header and body of the input.
     *
     * @param string The input to decode
     * @access public
     */
    function Mail_mimeDecode($input)
    {
        list($header, $body)   = $this->_splitBodyHeader($input);

        $this->_input          = $input;
        $this->_header         = $header;
        $this->_body           = $body;
        $this->_decode_bodies  = false;
        $this->_include_bodies = true;
    }

    /**
     * Begins the decoding process. If called statically
     * it will create an object and call the decode() method
     * of it.
     *
     * @param array An array of various parameters that determine
     *              various things:
     *              include_bodies - Whether to include the body in the returned
     *                               object.
     *              decode_bodies  - Whether to decode the bodies
     *                               of the parts. (Transfer encoding)
     *              decode_headers - Whether to decode headers
     *              input          - If called statically, this will be treated
     *                               as the input
     * @return object Decoded results
     * @access public
     */
    function decode($params = null)
    {
        // determine if this method has been called statically
        $isStatic = !(isset($this) && get_class($this) == __CLASS__);

        // Have we been called statically?
	// If so, create an object and pass details to that.
        if ($isStatic AND isset($params['input'])) {

            $obj = new Mail_mimeDecode($params['input']);
            $structure = $obj->decode($params);

        // Called statically but no input
        } elseif ($isStatic) {
            return PEAR::raiseError('Called statically and no input given');

        // Called via an object
        } else {
            $this->_include_bodies = isset($params['include_bodies']) ?
	                             $params['include_bodies'] : false;
            $this->_decode_bodies  = isset($params['decode_bodies']) ?
	                             $params['decode_bodies']  : false;
            $this->_decode_headers = isset($params['decode_headers']) ?
	                             $params['decode_headers'] : false;

            $structure = $this->_decode($this->_header, $this->_body);
            if ($structure === false) {
                $structure = $this->raiseError($this->_error);
            }
        }

        return $structure;
    }

    /**
     * Performs the decoding. Decodes the body string passed to it
     * If it finds certain content-types it will call itself in a
     * recursive fashion
     *
     * @param string Header section
     * @param string Body section
     * @return object Results of decoding process
     * @access private
     */
    function _decode($headers, $body, $default_ctype = 'text/plain')
    {
        $return = new stdClass;
        $return->headers = array();
        $headers = $this->_parseHeaders($headers);

        foreach ($headers as $value) {
            if (isset($return->headers[strtolower($value['name'])]) AND !is_array($return->headers[strtolower($value['name'])])) {
                $return->headers[strtolower($value['name'])]   = array($return->headers[strtolower($value['name'])]);
                $return->headers[strtolower($value['name'])][] = $value['value'];

            } elseif (isset($return->headers[strtolower($value['name'])])) {
                $return->headers[strtolower($value['name'])][] = $value['value'];

            } else {
                $return->headers[strtolower($value['name'])] = $value['value'];
            }
        }

        reset($headers);
        while (list($key, $value) = each($headers)) {
            $headers[$key]['name'] = strtolower($headers[$key]['name']);
            switch ($headers[$key]['name']) {

                case 'content-type':
                    $content_type = $this->_parseHeaderValue($headers[$key]['value']);

                    if (preg_match('/([0-9a-z+.-]+)\/([0-9a-z+.-]+)/i', $content_type['value'], $regs)) {
                        $return->ctype_primary   = $regs[1];
                        $return->ctype_secondary = $regs[2];
                    }

                    if (isset($content_type['other'])) {
                        while (list($p_name, $p_value) = each($content_type['other'])) {
                            $return->ctype_parameters[$p_name] = $p_value;
                        }
                    }
                    break;

                case 'content-disposition':
                    $content_disposition = $this->_parseHeaderValue($headers[$key]['value']);
                    $return->disposition   = $content_disposition['value'];
                    if (isset($content_disposition['other'])) {
                        while (list($p_name, $p_value) = each($content_disposition['other'])) {
                            $return->d_parameters[$p_name] = $p_value;
                        }
                    }
                    break;

                case 'content-transfer-encoding':
                    $content_transfer_encoding = $this->_parseHeaderValue($headers[$key]['value']);
                    break;
            }
        }

        if (isset($content_type)) {
            switch (strtolower($content_type['value'])) {
                case 'text/plain':
                    $encoding = isset($content_transfer_encoding) ? $content_transfer_encoding['value'] : '7bit';
                    $this->_include_bodies ? $return->body = ($this->_decode_bodies ? $this->_decodeBody($body, $encoding) : $body) : null;
                    break;

                case 'text/html':
                    $encoding = isset($content_transfer_encoding) ? $content_transfer_encoding['value'] : '7bit';
                    $this->_include_bodies ? $return->body = ($this->_decode_bodies ? $this->_decodeBody($body, $encoding) : $body) : null;
                    break;

                case 'multipart/parallel':
                case 'multipart/report': // RFC1892
                case 'multipart/signed': // PGP
                case 'multipart/digest':
                case 'multipart/alternative':
                case 'multipart/related':
                case 'multipart/mixed':
                    if(!isset($content_type['other']['boundary'])){
                        $this->_error = 'No boundary found for ' . $content_type['value'] . ' part';
                        return false;
                    }

                    $default_ctype = (strtolower($content_type['value']) === 'multipart/digest') ? 'message/rfc822' : 'text/plain';

                    $parts = $this->_boundarySplit($body, $content_type['other']['boundary']);
                    for ($i = 0; $i < count($parts); $i++) {
                        list($part_header, $part_body) = $this->_splitBodyHeader($parts[$i]);
                        $part = $this->_decode($part_header, $part_body, $default_ctype);
                        if($part === false)
                            $part = $this->raiseError($this->_error);
                        $return->parts[] = $part;
                    }
                    break;

                case 'message/rfc822':
                    $obj = &new Mail_mimeDecode($body);
                    $return->parts[] = $obj->decode(array('include_bodies' => $this->_include_bodies,
					                                      'decode_bodies'  => $this->_decode_bodies,
														  'decode_headers' => $this->_decode_headers));
                    unset($obj);
                    break;

                default:
                    if(!isset($content_transfer_encoding['value']))
                        $content_transfer_encoding['value'] = '7bit';
                    $this->_include_bodies ? $return->body = ($this->_decode_bodies ? $this->_decodeBody($body, $content_transfer_encoding['value']) : $body) : null;
                    break;
            }

        } else {
            $ctype = explode('/', $default_ctype);
            $return->ctype_primary   = $ctype[0];
            $return->ctype_secondary = $ctype[1];
            $this->_include_bodies ? $return->body = ($this->_decode_bodies ? $this->_decodeBody($body) : $body) : null;
        }

        return $return;
    }

    /**
     * Given the output of the above function, this will return an
     * array of references to the parts, indexed by mime number.
     *
     * @param  object $structure   The structure to go through
     * @param  string $mime_number Internal use only.
     * @return array               Mime numbers
     */
    function &getMimeNumbers(&$structure, $no_refs = false, $mime_number = '', $prepend = '')
    {
        $return = array();
        if (!empty($structure->parts)) {
            if ($mime_number != '') {
                $structure->mime_id = $prepend . $mime_number;
                $return[$prepend . $mime_number] = &$structure;
            }
            for ($i = 0; $i < count($structure->parts); $i++) {

            
                if (!empty($structure->headers['content-type']) AND substr(strtolower($structure->headers['content-type']), 0, 8) == 'message/') {
                    $prepend      = $prepend . $mime_number . '.';
                    $_mime_number = '';
                } else {
                    $_mime_number = ($mime_number == '' ? $i + 1 : sprintf('%s.%s', $mime_number, $i + 1));
                }

                $arr = &Mail_mimeDecode::getMimeNumbers($structure->parts[$i], $no_refs, $_mime_number, $prepend);
                foreach ($arr as $key => $val) {
                    $no_refs ? $return[$key] = '' : $return[$key] = &$arr[$key];
                }
            }
        } else {
            if ($mime_number == '') {
                $mime_number = '1';
            }
            $structure->mime_id = $prepend . $mime_number;
            $no_refs ? $return[$prepend . $mime_number] = '' : $return[$prepend . $mime_number] = &$structure;
        }
        
        return $return;
    }

    /**
     * Given a string containing a header and body
     * section, this function will split them (at the first
     * blank line) and return them.
     *
     * @param string Input to split apart
     * @return array Contains header and body section
     * @access private
     */
    function _splitBodyHeader($input)
    {
        if (preg_match("/^(.*?)\r?\n\r?\n(.*)/s", $input, $match)) {
            return array($match[1], $match[2]);
        }
        $this->_error = 'Could not split header and body';
        return false;
    }

    /**
     * Parse headers given in $input and return
     * as assoc array.
     *
     * @param string Headers to parse
     * @return array Contains parsed headers
     * @access private
     */
    function _parseHeaders($input)
    {

        if ($input !== '') {
            // Unfold the input
            $input   = preg_replace("/\r?\n/", "\r\n", $input);
            $input   = preg_replace("/\r\n(\t| )+/", ' ', $input);
            $headers = explode("\r\n", trim($input));

            foreach ($headers as $value) {
                $hdr_name = substr($value, 0, $pos = strpos($value, ':'));
                $hdr_value = substr($value, $pos+1);
                if($hdr_value[0] == ' ')
                    $hdr_value = substr($hdr_value, 1);

                $return[] = array(
                                  'name'  => $hdr_name,
                                  'value' => $this->_decode_headers ? $this->_decodeHeader($hdr_value) : $hdr_value
                                 );
            }
        } else {
            $return = array();
        }

        return $return;
    }

    /**
     * Function to parse a header value,
     * extract first part, and any secondary
     * parts (after ;) This function is not as
     * robust as it could be. Eg. header comments
     * in the wrong place will probably break it.
     *
     * @param string Header value to parse
     * @return array Contains parsed result
     * @access private
     */
    function _parseHeaderValue($input)
    {

        if (($pos = strpos($input, ';')) !== false) {

            $return['value'] = trim(substr($input, 0, $pos));
            $input = trim(substr($input, $pos+1));

            if (strlen($input) > 0) {

                // This splits on a semi-colon, if there's no preceeding backslash
                // Now works with quoted values; had to glue the \; breaks in PHP
                // the regex is already bordering on incomprehensible
                $splitRegex = '/([^;\'"]*[\'"]([^\'"]*([^\'"]*)*)[\'"][^;\'"]*|([^;]+))(;|$)/';
                preg_match_all($splitRegex, $input, $matches);
                $parameters = array();
                for ($i=0; $i<count($matches[0]); $i++) {
                    $param = $matches[0][$i];
                    while (substr($param, -2) == '\;') {
                        $param .= $matches[0][++$i];
                    }
                    $parameters[] = $param;
                }

                for ($i = 0; $i < count($parameters); $i++) {
                    $param_name  = trim(substr($parameters[$i], 0, $pos = strpos($parameters[$i], '=')), "'\";\t\\ ");
                    $param_value = trim(str_replace('\;', ';', substr($parameters[$i], $pos + 1)), "'\";\t\\ ");
                    if ($param_value[0] == '"') {
                        $param_value = substr($param_value, 1, -1);
                    }
                    $return['other'][$param_name] = $param_value;
                    $return['other'][strtolower($param_name)] = $param_value;
                }
            }
        } else {
            $return['value'] = trim($input);
        }

        return $return;
    }

    /**
     * This function splits the input based
     * on the given boundary
     *
     * @param string Input to parse
     * @return array Contains array of resulting mime parts
     * @access private
     */
    function _boundarySplit($input, $boundary)
    {
        $parts = array();

        $bs_possible = substr($boundary, 2, -2);
        $bs_check = '\"' . $bs_possible . '\"';

        if ($boundary == $bs_check) {
            $boundary = $bs_possible;
        }

        $tmp = explode('--' . $boundary, $input);

        for ($i = 1; $i < count($tmp) - 1; $i++) {
            $parts[] = $tmp[$i];
        }

        return $parts;
    }

    /**
     * Given a header, this function will decode it
     * according to RFC2047. Probably not *exactly*
     * conformant, but it does pass all the given
     * examples (in RFC2047).
     *
     * @param string Input header value to decode
     * @return string Decoded header value
     * @access private
     */
    function _decodeHeader($input)
    {
        // Remove white space between encoded-words
        $input = preg_replace('/(=\?[^?]+\?(q|b)\?[^?]*\?=)(\s)+=\?/i', '\1=?', $input);

        // For each encoded-word...
        while (preg_match('/(=\?([^?]+)\?(q|b)\?([^?]*)\?=)/i', $input, $matches)) {

            $encoded  = $matches[1];
            $charset  = $matches[2];
            $encoding = $matches[3];
            $text     = $matches[4];

            switch (strtolower($encoding)) {
                case 'b':
                    $text = base64_decode($text);
                    break;

                case 'q':
                    $text = str_replace('_', ' ', $text);
                    preg_match_all('/=([a-f0-9]{2})/i', $text, $matches);
                    foreach($matches[1] as $value)
                        $text = str_replace('='.$value, chr(hexdec($value)), $text);
                    break;
            }

            $input = str_replace($encoded, $text, $input);
        }

        return $input;
    }

    /**
     * Given a body string and an encoding type,
     * this function will decode and return it.
     *
     * @param  string Input body to decode
     * @param  string Encoding type to use.
     * @return string Decoded body
     * @access private
     */
    function _decodeBody($input, $encoding = '7bit')
    {
        switch (strtolower($encoding)) {
            case '7bit':
                return $input;
                break;

            case 'quoted-printable':
                return $this->_quotedPrintableDecode($input);
                break;

            case 'base64':
                return base64_decode($input);
                break;

            default:
                return $input;
        }
    }

    /**
     * Given a quoted-printable string, this
     * function will decode and return it.
     *
     * @param  string Input body to decode
     * @return string Decoded body
     * @access private
     */
    function _quotedPrintableDecode($input)
    {
        // Remove soft line breaks
        $input = preg_replace("/=\r?\n/", '', $input);

        // Replace encoded characters
		$input = preg_replace('/=([a-f0-9]{2})/ie', "chr(hexdec('\\1'))", $input);

        return $input;
    }

    /**
     * Checks the input for uuencoded files and returns
     * an array of them. Can be called statically, eg:
     *
     * $files =& Mail_mimeDecode::uudecode($some_text);
     *
     * It will check for the begin 666 ... end syntax
     * however and won't just blindly decode whatever you
     * pass it.
     *
     * @param  string Input body to look for attahcments in
     * @return array  Decoded bodies, filenames and permissions
     * @access public
     * @author Unknown
     */
    function &uudecode($input)
    {
        // Find all uuencoded sections
        preg_match_all("/begin ([0-7]{3}) (.+)\r?\n(.+)\r?\nend/Us", $input, $matches);

        for ($j = 0; $j < count($matches[3]); $j++) {

            $str      = $matches[3][$j];
            $filename = $matches[2][$j];
            $fileperm = $matches[1][$j];

            $file = '';
            $str = preg_split("/\r?\n/", trim($str));
            $strlen = count($str);

            for ($i = 0; $i < $strlen; $i++) {
                $pos = 1;
                $d = 0;
                $len=(int)(((ord(substr($str[$i],0,1)) -32) - ' ') & 077);

                while (($d + 3 <= $len) AND ($pos + 4 <= strlen($str[$i]))) {
                    $c0 = (ord(substr($str[$i],$pos,1)) ^ 0x20);
                    $c1 = (ord(substr($str[$i],$pos+1,1)) ^ 0x20);
                    $c2 = (ord(substr($str[$i],$pos+2,1)) ^ 0x20);
                    $c3 = (ord(substr($str[$i],$pos+3,1)) ^ 0x20);
                    $file .= chr(((($c0 - ' ') & 077) << 2) | ((($c1 - ' ') & 077) >> 4));

                    $file .= chr(((($c1 - ' ') & 077) << 4) | ((($c2 - ' ') & 077) >> 2));

                    $file .= chr(((($c2 - ' ') & 077) << 6) |  (($c3 - ' ') & 077));

                    $pos += 4;
                    $d += 3;
                }

                if (($d + 2 <= $len) && ($pos + 3 <= strlen($str[$i]))) {
                    $c0 = (ord(substr($str[$i],$pos,1)) ^ 0x20);
                    $c1 = (ord(substr($str[$i],$pos+1,1)) ^ 0x20);
                    $c2 = (ord(substr($str[$i],$pos+2,1)) ^ 0x20);
                    $file .= chr(((($c0 - ' ') & 077) << 2) | ((($c1 - ' ') & 077) >> 4));

                    $file .= chr(((($c1 - ' ') & 077) << 4) | ((($c2 - ' ') & 077) >> 2));

                    $pos += 3;
                    $d += 2;
                }

                if (($d + 1 <= $len) && ($pos + 2 <= strlen($str[$i]))) {
                    $c0 = (ord(substr($str[$i],$pos,1)) ^ 0x20);
                    $c1 = (ord(substr($str[$i],$pos+1,1)) ^ 0x20);
                    $file .= chr(((($c0 - ' ') & 077) << 2) | ((($c1 - ' ') & 077) >> 4));

                }
            }
            $files[] = array('filename' => $filename, 'fileperm' => $fileperm, 'filedata' => $file);
        }

        return $files;
    }

    /**
     * getSendArray() returns the arguments required for Mail::send()
     * used to build the arguments for a mail::send() call 
     *
     * Usage:
     * $mailtext = Full email (for example generated by a template)
     * $decoder = new Mail_mimeDecode($mailtext);
     * $parts =  $decoder->getSendArray();
     * if (!PEAR::isError($parts) {
     *     list($recipents,$headers,$body) = $parts;
     *     $mail = Mail::factory('smtp');
     *     $mail->send($recipents,$headers,$body);
     * } else {
     *     echo $parts->message;
     * }
     * @return mixed   array of recipeint, headers,body or Pear_Error
     * @access public
     * @author Alan Knowles <alan@akbkhome.com>
     */
    function getSendArray()
    {
        // prevent warning if this is not set
        $this->_decode_headers = FALSE;
        $headerlist =$this->_parseHeaders($this->_header);
        $to = "";
        if (!$headerlist) {
            return $this->raiseError("Message did not contain headers");
        }
        foreach($headerlist as $item) {
            $header[$item['name']] = $item['value'];
            switch (strtolower($item['name'])) {
                case "to":
                case "cc":
                case "bcc":
                    $to = ",".$item['value'];
                default:
                   break;
            }
        }
        if ($to == "") {
            return $this->raiseError("Message did not contain any recipents");
        }
        $to = substr($to,1);
        return array($to,$header,$this->_body);
    } 

    /**
     * Returns a xml copy of the output of
     * Mail_mimeDecode::decode. Pass the output in as the
     * argument. This function can be called statically. Eg:
     *
     * $output = $obj->decode();
     * $xml    = Mail_mimeDecode::getXML($output);
     *
     * The DTD used for this should have been in the package. Or
     * alternatively you can get it from cvs, or here:
     * http://www.phpguru.org/xmail/xmail.dtd.
     *
     * @param  object Input to convert to xml. This should be the
     *                output of the Mail_mimeDecode::decode function
     * @return string XML version of input
     * @access public
     */
    function getXML($input)
    {
        $crlf    =  "\r\n";
        $output  = '<?xml version=\'1.0\'?>' . $crlf .
                   '<!DOCTYPE email SYSTEM "http://www.phpguru.org/xmail/xmail.dtd">' . $crlf .
                   '<email>' . $crlf .
                   Mail_mimeDecode::_getXML($input) .
                   '</email>';

        return $output;
    }

    /**
     * Function that does the actual conversion to xml. Does a single
     * mimepart at a time.
     *
     * @param  object  Input to convert to xml. This is a mimepart object.
     *                 It may or may not contain subparts.
     * @param  integer Number of tabs to indent
     * @return string  XML version of input
     * @access private
     */
    function _getXML($input, $indent = 1)
    {
        $htab    =  "\t";
        $crlf    =  "\r\n";
        $output  =  '';
        $headers = @(array)$input->headers;

        foreach ($headers as $hdr_name => $hdr_value) {

            // Multiple headers with this name
            if (is_array($headers[$hdr_name])) {
                for ($i = 0; $i < count($hdr_value); $i++) {
                    $output .= Mail_mimeDecode::_getXML_helper($hdr_name, $hdr_value[$i], $indent);
                }

            // Only one header of this sort
            } else {
                $output .= Mail_mimeDecode::_getXML_helper($hdr_name, $hdr_value, $indent);
            }
        }

        if (!empty($input->parts)) {
            for ($i = 0; $i < count($input->parts); $i++) {
                $output .= $crlf . str_repeat($htab, $indent) . '<mimepart>' . $crlf .
                           Mail_mimeDecode::_getXML($input->parts[$i], $indent+1) .
                           str_repeat($htab, $indent) . '</mimepart>' . $crlf;
            }
        } elseif (isset($input->body)) {
            $output .= $crlf . str_repeat($htab, $indent) . '<body><![CDATA[' .
                       $input->body . ']]></body>' . $crlf;
        }

        return $output;
    }

    /**
     * Helper function to _getXML(). Returns xml of a header.
     *
     * @param  string  Name of header
     * @param  string  Value of header
     * @param  integer Number of tabs to indent
     * @return string  XML version of input
     * @access private
     */
    function _getXML_helper($hdr_name, $hdr_value, $indent)
    {
        $htab   = "\t";
        $crlf   = "\r\n";
        $return = '';

        $new_hdr_value = ($hdr_name != 'received') ? Mail_mimeDecode::_parseHeaderValue($hdr_value) : array('value' => $hdr_value);
        $new_hdr_name  = str_replace(' ', '-', ucwords(str_replace('-', ' ', $hdr_name)));

        // Sort out any parameters
        if (!empty($new_hdr_value['other'])) {
            foreach ($new_hdr_value['other'] as $paramname => $paramvalue) {
                $params[] = str_repeat($htab, $indent) . $htab . '<parameter>' . $crlf .
                            str_repeat($htab, $indent) . $htab . $htab . '<paramname>' . htmlspecialchars($paramname) . '</paramname>' . $crlf .
                            str_repeat($htab, $indent) . $htab . $htab . '<paramvalue>' . htmlspecialchars($paramvalue) . '</paramvalue>' . $crlf .
                            str_repeat($htab, $indent) . $htab . '</parameter>' . $crlf;
            }

            $params = implode('', $params);
        } else {
            $params = '';
        }

        $return = str_repeat($htab, $indent) . '<header>' . $crlf .
                  str_repeat($htab, $indent) . $htab . '<headername>' . htmlspecialchars($new_hdr_name) . '</headername>' . $crlf .
                  str_repeat($htab, $indent) . $htab . '<headervalue>' . htmlspecialchars($new_hdr_value['value']) . '</headervalue>' . $crlf .
                  $params .
                  str_repeat($htab, $indent) . '</header>' . $crlf;

        return $return;
    }

} // End of class
?>