<?php

/**
 * mime.php
 *
 * This contains the functions necessary to detect and decode MIME
 * messages.
 *
 * @copyright 1999-2026 The SquirrelMail Project Team
 * @license http://opensource.org/licenses/gpl-license.php GNU Public License
 * @version $Id: mime.php 15056 2026-04-01 04:29:50Z pdontthink $
 * @package squirrelmail
 */

/** The typical includes... */
require_once(SM_PATH . 'functions/imap.php');
require_once(SM_PATH . 'functions/attachment_common.php');

/* -------------------------------------------------------------------------- */
/* MIME DECODING                                                              */
/* -------------------------------------------------------------------------- */

/**
 * Get the MIME structure
 *
 * This function gets the structure of a message and stores it in the "message" class.
 * It will return this object for use with all relevant header information and
 * fully parsed into the standard "message" object format.
 */
function mime_structure ($bodystructure, $flags=array()) {

    /* Isolate the body structure and remove beginning and end parenthesis. */
    $read = trim(substr ($bodystructure, strpos(strtolower($bodystructure), 'bodystructure') + 13));
    $read = trim(substr ($read, 0, -1));
    $i = 0;
    $msg = Message::parseStructure($read,$i);
    if (!is_object($msg)) {
        include_once(SM_PATH . 'functions/display_messages.php');
        global $color, $mailbox;
        /* removed urldecode because $_GET is auto urldecoded ??? */
        displayPageHeader( $color, $mailbox );
        echo "<body text=\"$color[8]\" bgcolor=\"$color[4]\" link=\"$color[7]\" vlink=\"$color[7]\" alink=\"$color[7]\">\n\n" .
         '<center>';
        $errormessage  = _("SquirrelMail could not decode the bodystructure of the message");
        $errormessage .= '<br />'._("The bodystructure provided by your IMAP server:").'<br /><br />';
        $errormessage .= '<table><tr><td>' . sm_encode_html_special_chars($read) . '</td></tr></table>';
        plain_error_message( $errormessage, $color );
        echo '</body></html>';
        exit;
    }
    if (count($flags)) {
        foreach ($flags as $flag) {
            $char = strtoupper($flag[1]);
            switch ($char) {
                case 'S':
                    if (strtolower($flag) == '\\seen') {
                        $msg->is_seen = true;
                    }
                    break;
                case 'A':
                    if (strtolower($flag) == '\\answered') {
                        $msg->is_answered = true;
                    }
                    break;
                case 'D':
                    if (strtolower($flag) == '\\deleted') {
                        $msg->is_deleted = true;
                    }
                    break;
                case 'F':
                    if (strtolower($flag) == '\\flagged') {
                        $msg->is_flagged = true;
                    }
                    break;
                case 'M':
                    if (strtolower($flag) == '$mdnsent') {
                        $msg->is_mdnsent = true;
                    }
                    break;
                default:
                    break;
            }
        }
    }
    //    listEntities($msg);
    return $msg;
}



/* This starts the parsing of a particular structure.  It is called recursively,
 * so it can be passed different structures.  It returns an object of type
 * $message.
 * First, it checks to see if it is a multipart message.  If it is, then it
 * handles that as it sees is necessary.  If it is just a regular entity,
 * then it parses it and adds the necessary header information (by calling out
 * to mime_get_elements()
 */

function mime_fetch_body($imap_stream, $id, $ent_id=1, $fetch_size=0) {
    global $uid_support;
    /* Do a bit of error correction.  If we couldn't find the entity id, just guess
     * that it is the first one.  That is usually the case anyway.
     */

    if (!$ent_id) {
        $cmd = "FETCH $id BODY[]";
    } else {
        $cmd = "FETCH $id BODY[$ent_id]";
    }

    if ($fetch_size!=0) $cmd .= "<0.$fetch_size>";

    $data = sqimap_run_command ($imap_stream, $cmd, true, $response, $message, $uid_support);
    do {
        $topline = trim(array_shift($data));
    } while($topline && ($topline[0] == '*') && !preg_match('/\* [0-9]+ FETCH .*BODY.*/i', $topline)) ;
    // Matching with "BODY" above is difficult: in most cases "FETCH \(BODY" would work
    // but some servers may put other things in the same result, perhaps something such
    // as "* 23 FETCH (FLAGS (\Seen) BODY[1] {174}".  There is some small chance that
    // if the character sequence "BODY" appears in a response where it isn't actually
    // a FETCH response data item name, the current regex will break things.  The better
    // way to do this would be to parse the response correctly and not use a regex.

    $wholemessage = implode('', $data);
    if (preg_match('/\{([^\}]*)\}/', $topline, $regs)) {
        $ret = substr($wholemessage, 0, $regs[1]);
        /* There is some information in the content info header that could be important
         * in order to parse html messages. Let's get them here.
         */
//        if ($ret[0] == '<') {
//            $data = sqimap_run_command ($imap_stream, "FETCH $id BODY[$ent_id.MIME]", true, $response, $message, $uid_support);
//        }
    } else if (preg_match('/"([^"]*)"/', $topline, $regs)) {
        $ret = $regs[1];
    } else if ((stristr($topline, 'nil') !== false) && (empty($wholemessage))) {
        $ret = $wholemessage;
    } else {
        global $where, $what, $mailbox, $passed_id, $startMessage;
        $par = 'mailbox=' . urlencode($mailbox) . '&amp;passed_id=' . $passed_id;
        if (isset($where) && isset($what)) {
            $par .= '&amp;where=' . urlencode($where) . '&amp;what=' . urlencode($what);
        } else {
            $par .= '&amp;startMessage=' . $startMessage . '&amp;show_more=0';
        }
        $par .= '&amp;response=' . urlencode($response) .
            '&amp;message='  . urlencode($message)  .
            '&amp;topline='  . urlencode($topline);

        echo '<tt><br />' .
            '<table width="80%"><tr>' .
            '<tr><td colspan="2">' .
            _("Body retrieval error. The reason for this is most probably that the message is malformed.") .
            '</td></tr>' .
            '<tr><td><b>' . _("Command:") . "</td><td>$cmd</td></tr>" .
            '<tr><td><b>' . _("Response:") . "</td><td>$response</td></tr>" .
            '<tr><td><b>' . _("Message:") . "</td><td>$message</td></tr>" .
            '<tr><td><b>' . _("FETCH line:") . "</td><td>$topline</td></tr>" .
            "</table><br /></tt></font><hr />";

        $data = sqimap_run_command ($imap_stream, "FETCH $passed_id BODY[]", true, $response, $message, $uid_support);
        array_shift($data);
        $wholemessage = implode('', $data);

        $ret = $wholemessage;
    }
    return $ret;
}

// TODO: Needs documentation.  $ent_id default is usually 1
function mime_print_body_lines ($imap_stream, $id, $ent_id, $encoding, $rStream='php://stdout') {
    global $uid_support;

    /* Don't kill the connection if the browser is over a dialup
     * and it would take over 30 seconds to download it.
     * Don't call set_time_limit in safe mode.
     */

    if (!ini_get('safe_mode')) {
        set_time_limit(0);
    }
    /* in case of base64 encoded attachments, do not buffer them.
       Instead, echo the decoded attachment directly to screen */
    if (strtolower($encoding) == 'base64') {
        if (!$ent_id) {
            $query = "FETCH $id BODY[]";
        } else {
            $query = "FETCH $id BODY[$ent_id]";
        }
        sqimap_run_command($imap_stream,$query,true,$response,$message,$uid_support,'sqimap_base64_decode',$rStream,true);
   } else {
        $body = mime_fetch_body ($imap_stream, $id, $ent_id);
        if ($rStream !== 'php://stdout') {
            fwrite($rStream, decodeBody($body, $encoding));
        } else {
            echo decodeBody($body, $encoding);
        }
    }
    return;
}

/* -[ END MIME DECODING ]----------------------------------------------------------- */

/* This is here for debugging purposes.  It will print out a list
 * of all the entity IDs that are in the $message object.
 */
function listEntities ($message) {
    if ($message) {
        echo "<tt>" . $message->entity_id . ' : ' . $message->type0 . '/' . $message->type1 . ' parent = '. $message->parent->entity_id. '<br />';
        for ($i = 0; isset($message->entities[$i]); $i++) {
            echo "$i : ";
            $msg = listEntities($message->entities[$i]);

            if ($msg) {
                echo "return: ";
                return $msg;
            }
        }
    }
}

function getPriorityStr($priority) {
    $priority_level = substr($priority,0,1);

    switch($priority_level) {
        /* Check for a higher then normal priority. */
        case '1':
        case '2':
            $priority_string = _("High");
            break;

        /* Check for a lower then normal priority. */
        case '4':
        case '5':
            $priority_string = _("Low");
            break;

        /* Check for a normal priority. */
        case '3':
        default:
            $priority_level = '3';
            $priority_string = _("Normal");
            break;

    }
    return $priority_string;
}

/* returns a $message object for a particular entity id */
function getEntity ($message, $ent_id) {
    return $message->getEntity($ent_id);
}

/* translateText
 * Extracted from strings.php 23/03/2002
 */

function translateText(&$body, $wrap_at, $charset) {
    global $where, $what;   /* from searching */
    global $color;          /* color theme */

    require_once(SM_PATH . 'functions/url_parser.php');

    $body_ary = explode("\n", $body);
    for ($i=0; $i < count($body_ary); $i++) {
        $line = $body_ary[$i];
        if (strlen($line) - 2 >= $wrap_at) {
            sqWordWrap($line, $wrap_at, $charset);
        }
        $line = charset_decode($charset, $line);
        $line = str_replace("\t", '        ', $line);

        parseUrl ($line);

        $quotes = 0;
        $pos = 0;
        $j = strlen($line);

        while ($pos < $j) {
            if ($line[$pos] == ' ') {
                $pos++;
            } else if (strpos($line, '&gt;', $pos) === $pos) {
                $pos += 4;
                $quotes++;
            } else {
                break;
            }
        }

        if ($quotes % 2) {
            if (!isset($color[13])) {
                $color[13] = '#800000';
            }
            $line = '<font color="' . $color[13] . '">' . $line . '</font>';
        } elseif ($quotes) {
            if (!isset($color[14])) {
                $color[14] = '#FF0000';
            }
            $line = '<font color="' . $color[14] . '">' . $line . '</font>';
        }

        $body_ary[$i] = $line;
    }
    $body = '<pre>' . implode("\n", $body_ary) . '</pre>';
}

/**
 * This returns a parsed string called $body. That string can then
 * be displayed as the actual message in the HTML. It contains
 * everything needed, including HTML Tags, Attachments at the
 * bottom, etc.
 */
function formatBody($imap_stream, $message, $color, $wrap_at, $ent_num, $id, $mailbox='INBOX',$clean=false) {
    /* This if statement checks for the entity to show as the
     * primary message. To add more of them, just put them in the
     * order that is their priority.
     */
    global $startMessage, $languages, $squirrelmail_language,
           $show_html_default, $sort, $has_unsafe_images, $passed_ent_id,
           $username, $key, $imapServerAddress, $imapPort,
           $download_and_unsafe_link;

    // If there's no "view_unsafe_images" variable in the URL, turn unsafe
    // images off by default.
    if( !sqgetGlobalVar('view_unsafe_images', $view_unsafe_images, SQ_GET) ) {
        $view_unsafe_images = false;
    }

    $body = '';
    $urlmailbox = urlencode($mailbox);
    $body_message = getEntity($message, $ent_num);
    if (($body_message->header->type0 == 'text') ||
            ($body_message->header->type0 == 'rfc822')) {
        $body = mime_fetch_body ($imap_stream, $id, $ent_num);
        $body = decodeBody($body, $body_message->header->encoding);

        if (isset($languages[$squirrelmail_language]['XTRA_CODE']) &&
                function_exists($languages[$squirrelmail_language]['XTRA_CODE'])) {
            if (mb_detect_encoding($body) != 'ASCII') {
                $body = $languages[$squirrelmail_language]['XTRA_CODE']('decode', $body);
            }
        }
        $hookResults = do_hook("message_body", $body);
        $body = $hookResults[1];

        /* If there are other types that shouldn't be formatted, add
         * them here.
         */

        if ($body_message->header->type1 == 'html') {
            // Do we need to make an HTML part viewable as non-HTML plain text?
            if ($show_html_default != 1) {
                $entity_conv = array('&nbsp;' => ' ',
                                     // These are better done by regex (below)
                                     // '<p>'    => "\n",
                                     // '<P>'    => "\n",
                                     // '<br>'   => "\n",
                                     // '<BR>'   => "\n",
                                     // '<br />' => "\n",
                                     // '<BR />' => "\n",
                                     // '<tr>'   => "\n",
                                     // '<div>'  => "\n",
                                     '&gt;'   => '>',
                                     '&lt;'   => '<',
                                     '&amp;'   => '&',
                                     '&copy;'   => '©');
                // first, completely remove <style> tags as they aren't useful in this context
                $body = preg_replace('/<style.*>.*<\/style.*>/isU', '', $body);
                // emulate how newlines are treated as spaces in HTML
                $body = preg_replace('/(\r|\n)+/', ' ', $body);
                // now replace the tags listed just above
                $body = strtr($body, $entity_conv);
                // <p>, <br>, <tr> and <div> are best replaced by a newline
                $body = preg_replace('/<(p|br|tr|div).*>/isU', "\n", $body);
                // remove the rest of the HTML tags
                $body = strip_tags($body);
                // condense multiple spaces into one
                $body = preg_replace('/[ \t]+/', ' ', $body);
                // trim each line
                $body = preg_replace('/ *\n */', "\n", $body);
                // allow maximum two newlines
                $body = preg_replace('/\n\n\n+/', "\n\n", $body);
                $body = trim($body);
                translateText($body, $wrap_at,
                        $body_message->header->getParameter('charset'));
            } else {
                $charset = $body_message->header->getParameter('charset');
                if (!empty($charset))
                    $body = charset_decode($charset,$body,false,true);
                $body = magicHTML($body, $id, $message, $mailbox);
            }
        } else {
            translateText($body, $wrap_at,
                    $body_message->header->getParameter('charset'));
        }

        // if this is the clean display (i.e. printer friendly), stop here.
        if ( $clean ) {
            return $body;
        }

        /*
         * Previously the links for downloading and unsafe images were printed
         * under the mail. By putting the links in a global variable we can
         * print it in the toolbar where it belongs. Since the original code was
         * in this place it's left here. It might be possible to move it to some
         * other place if that makes sense. The possibility to do so has not
         * been evaluated yet.
         */

        // Initialize the global variable to an empty string.
        $download_and_unsafe_link = '';

        // Prepare and build a link for downloading the mail.
        $link = 'passed_id=' . $id . '&amp;ent_id='.$ent_num.
            '&amp;mailbox=' . $urlmailbox .'&amp;sort=' . $sort .
            '&amp;startMessage=' . $startMessage . '&amp;show_more=0';
        if (isset($passed_ent_id)) {
            $link .= '&amp;passed_ent_id='.$passed_ent_id;
        }

        // Always add the link for downloading the mail as a file to the global
        // variable.
        $download_and_unsafe_link .= '&nbsp;| <a href="download.php?absolute_dl=true&amp;' .
            $link . '" style="white-space: nowrap;">' . _("Download this as a file") .  '</a>';

        // Find out the right text to use in the link depending on the
        // circumstances. If the unsafe images are displayed the link should
        // hide them, if they aren't displayed the link should only appear if
        // the mail really contains unsafe images.
        if ($view_unsafe_images) {
            $text = _("Hide Unsafe Images");
        } else {
            if (isset($has_unsafe_images) && $has_unsafe_images) {
                $link .= '&amp;view_unsafe_images=1';
                $text = _("View Unsafe Images");
            } else {
                $text = '';
            }
        }

        // Only create a link for unsafe images if there's need for one. If so:
        // add it to the global variable.
        if($text != '') {
            $download_and_unsafe_link .= '&nbsp;| <a href="read_body.php?' . $link . '" style="white-space: nowrap;">' . $text . '</a>';
        }
    }
    return $body;
}


function formatAttachments($message, $exclude_id, $mailbox, $id) {
    global $where, $what, $startMessage, $color, $passed_ent_id, $block_svg_download;
    static $ShownHTML = 0;

    $att_ar = $message->getAttachments($exclude_id);

    if (!count($att_ar)) return '';

    $attachments = '';

    $urlMailbox = urlencode($mailbox);

    foreach ($att_ar as $att) {
        $ent = $att->entity_id;
        $header = $att->header;
        $type0 = strtolower($header->type0);
        $type1 = strtolower($header->type1);
        if ($block_svg_download && strpos($type1, 'svg') === 0)
            continue;

        $name = '';
        $links['download link']['text'] = _("Download");
        $links['download link']['href'] = SM_PATH .
            "src/download.php?absolute_dl=true&amp;passed_id=$id&amp;mailbox=$urlMailbox&amp;ent_id=$ent";
        $ImageURL = '';
        if ($type0 =='message' && $type1 == 'rfc822') {
            $default_page = SM_PATH . 'src/read_body.php';
            $rfc822_header = $att->rfc822_header;
            $filename = $rfc822_header->subject;
            if (trim( $filename ) == '') {
                $filename = 'untitled-[' . $ent . ']' ;
            }
            $from_o = $rfc822_header->from;
            if (is_object($from_o)) {
                $from_name = $from_o->getAddress(false);
            } elseif (is_array($from_o) && count($from_o) && is_object($from_o[0])) {
                // when a digest message is opened and you return to the digest
                // now the from object is part of an array. This is a workaround.
                $from_name = $from_o[0]->getAddress(false);
            } else {
                $from_name = _("Unknown sender");
            }
            $from_name = decodeHeader(($from_name));
            $description = $from_name;
        } else {
            $default_page = SM_PATH . 'src/download.php';
            if (is_object($header->disposition)) {
                $filename = $header->disposition->getProperty('filename');
                if (trim($filename) == '') {
                    $name = decodeHeader($header->disposition->getProperty('name'));
                    if (trim($name) == '') {
                        $name = $header->getParameter('name');
                        if(trim($name) == '') {
                            if (trim( $header->id ) == '') {
                                $filename = 'untitled-[' . $ent . ']' . '.' . strtolower($header->type1);
                            } else {
                                $filename = 'cid: ' . $header->id . '.' . strtolower($header->type1);
                            }
                        } else {
                            $filename = $name;
                        }
                    } else {
                        $filename = $name;
                    }
                }
            } else {
                $filename = $header->getParameter('name');
                if (!trim($filename)) {
                    if (trim( $header->id ) == '') {
                        $filename = 'untitled-[' . $ent . ']' . '.' . strtolower($header->type1) ;
                    } else {
                        $filename = 'cid: ' . $header->id . '.' . strtolower($header->type1);
                    }
                }
            }
            if ($header->description) {
                $description = decodeHeader($header->description);
            } else {
                $description = '';
            }
        }

        $display_filename = $filename;
        if (isset($passed_ent_id)) {
            $passed_ent_id_link = '&amp;passed_ent_id='.$passed_ent_id;
        } else {
            $passed_ent_id_link = '';
        }
        $defaultlink = $default_page . "?startMessage=$startMessage"
            . "&amp;passed_id=$id&amp;mailbox=$urlMailbox"
            . '&amp;ent_id='.$ent.$passed_ent_id_link;
        if ($where && $what) {
           $defaultlink .= '&amp;where='. urlencode($where).'&amp;what='.urlencode($what);
        }
        // IE does make use of mime content sniffing. Forcing a download
        // prohibit execution of XSS inside an application/octet-stream attachment
        if ($type0 == 'application' && $type1 == 'octet-stream') {
            $defaultlink .= '&amp;absolute_dl=true';
        }
        /* This executes the attachment hook with a specific MIME-type.
         * If that doesn't have results, it tries if there's a rule
         * for a more generic type. Finally, a hook for ALL attachment
         * types is run as well.
         */
        $hookresults = do_hook("attachment $type0/$type1", $links,
                $startMessage, $id, $urlMailbox, $ent, $defaultlink,
                $display_filename, $where, $what, $type0, $type1);
        $hookresults = do_hook("attachment $type0/*", $hookresults[1],
                $startMessage, $id, $urlMailbox, $ent, $hookresults[6],
                $display_filename, $where, $what, $type0, $type1);
        $hookresults = do_hook("attachment */*", $hookresults[1],
                $startMessage, $id, $urlMailbox, $ent, $hookresults[6],
                $display_filename, $where, $what, $type0, $type1);

        $links = $hookresults[1];
        $defaultlink = $hookresults[6];

        // base64 encoded file sizes are misleading, so approximate real size
        if (!empty($header->encoding) && strtolower($header->encoding) == 'base64')
            $size = $header->size / 4 * 3;
        else
            $size = $header->size;

        $attachments .= '<tr><td>' .
            '<a href="'.$defaultlink.'">'.decodeHeader($display_filename).'</a>&nbsp;</td>' .
            '<td><small><b>' . show_readable_size($size) .
            '</b>&nbsp;&nbsp;</small></td>' .
            '<td><small>[ '.sm_encode_html_special_chars($type0).'/'.sm_encode_html_special_chars($type1).' ]&nbsp;</small></td>' .
            '<td><small>';
        $attachments .= '<b>' . $description . '</b>';
        $attachments .= '</small></td><td><small>&nbsp;';

        $skipspaces = 1;
        foreach ($links as $val) {
            if ($skipspaces) {
                $skipspaces = 0;
            } else {
                $attachments .= '&nbsp;&nbsp;|&nbsp;&nbsp;';
            }
            if (empty($val['href']))
               $attachments .= '<span '
                            . (!empty($val['extra']) ? $val['extra'] : '')
                            . '>' .  $val['text'] . '</span>';
            else
               $attachments .= '<a href="' . $val['href'] . '" '
                            . (!empty($val['extra']) ? $val['extra'] : '')
                            . '>' .  $val['text'] . '</a>';
        }
        unset($links);
        $attachments .= "</td></tr>\n";
    }
    return $attachments;
}

function sqimap_base64_decode(&$string) {

    // Base64 encoded data goes in pairs of 4 bytes. To achieve on the
    // fly decoding (to reduce memory usage) you have to check if the
    // data has incomplete pairs

    // Remove the noise in order to check if the 4 bytes pairs are complete
    $string = str_replace(array("\r\n","\n", "\r", " "),array('','','',''),$string);

    $sStringRem = '';
    $iMod = strlen($string) % 4;
    if ($iMod) {
        $sStringRem = substr($string,-$iMod);
        // Check if $sStringRem contains padding characters
        if (substr($sStringRem,-1) != '=') {
            $string = substr($string,0,-$iMod);
        } else {
            $sStringRem = '';
        }
    }
    $string = base64_decode($string);
    return $sStringRem;
}

/**
 * Decodes encoded message body
 *
 * This function decodes the body depending on the encoding type.
 * Currently quoted-printable and base64 encodings are supported.
 * decode_body hook was added to this function in 1.4.2/1.5.0
 * @param string $body encoded message body
 * @param string $encoding used encoding
 * @return string decoded string
 * @since 1.0
 */
function decodeBody($body, $encoding) {

    $body = str_replace("\r\n", "\n", $body);
    $encoding = strtolower($encoding);

    $encoding_handler = do_hook_function('decode_body', $encoding);

    // plugins get first shot at decoding the body
    if (!empty($encoding_handler) && function_exists($encoding_handler)) {
        $body = $encoding_handler('decode', $body);

    } elseif ($encoding == 'quoted-printable' ||
            $encoding == 'quoted_printable') {
        /**
         * quoted_printable_decode() function is broken in older
         * php versions. Text with \r\n decoding was fixed only
         * in php 4.3.0. Minimal code requirement 4.0.4 +
         * str_replace("\r\n", "\n", $body); call.
         */
        $body = quoted_printable_decode($body);
    } elseif ($encoding == 'base64') {
        $body = base64_decode($body);
    }

    // All other encodings are returned raw.
    return $body;
}

/**
 * Decodes headers
 *
 * This functions decode strings that is encoded according to
 * RFC1522 (MIME Part Two: Message Header Extensions for Non-ASCII Text).
 * Patched by Christian Schmidt <christian@ostenfeld.dk>  23/03/2002
 */
function decodeHeader ($string, $utfencode=true,$htmlsave=true,$decide=false) {
    global $languages, $squirrelmail_language,$default_charset, $fix_broken_base64_encoded_messages;
    if (is_array($string)) {
        $string = implode("\n", $string);
    }

    // loose type checking also catches $string === NULL here:
    if ($string == '')
        return '';

    if (isset($languages[$squirrelmail_language]['XTRA_CODE']) &&
            function_exists($languages[$squirrelmail_language]['XTRA_CODE'])) {
        $string = $languages[$squirrelmail_language]['XTRA_CODE']('decodeheader', $string);
        // Do we need to return at this point?
        // return $string;
    }
    $i = 0;
    $iLastMatch = -2;
    $encoded = false;

// FIXME: spaces are allowed inside quoted-printable encoding, but the following line will bust up any such encoded strings
    $aString = explode(' ',$string);
    $ret = '';
    foreach ($aString as $chunk) {
        if ($encoded && $chunk === '') {
            continue;
        } elseif ($chunk === '') {
            $ret .= ' ';
            continue;
        }
        $encoded = false;
        /* if encoded words are not separated by a linear-space-white we still catch them */
        $j = $i-1;

        while ($match = preg_match('/^(.*)=\?([^?]*)\?(Q|B)\?([^?]*)\?=(.*)$/Ui',$chunk,$res)) {
            /* if the last chunk isn't an encoded string then put back the space, otherwise don't */
            if ($iLastMatch !== $j) {
                if ($htmlsave) {
                    $ret .= '&#32;';
                } else {
                    $ret .= ' ';
                }
            }
            $iLastMatch = $i;
            $j = $i;
            if ($htmlsave) {
                $ret .= sm_encode_html_special_chars($res[1]);
            } else {
                $ret .= $res[1];
            }
            $encoding = ucfirst($res[3]);

            /* decide about valid decoding */
            if ($decide && is_conversion_safe($res[2])) {
                $can_be_encoded=true;
            } else {
                $can_be_encoded=false;
            }

            switch ($encoding)
            {
                case 'B':
                    // fix broken base64-encoded strings (remove end = padding,
                    // change any = to + in middle of string, add padding back
                    // to the end)
                    if ($fix_broken_base64_encoded_messages) {
                        $encoded_string_minus_padding = strtr(rtrim($res[4], '='), '=', '+');
                        $res[4] = str_pad($encoded_string_minus_padding, strlen($res[4]), '=');
                    }
                    $replace = base64_decode($res[4]);
                    if ($can_be_encoded) {
                        // string is converted from one charset to another. sanitizing depends on $htmlsave
                        $replace =  charset_convert($res[2],$replace,$default_charset,$htmlsave);
                    } elseif ($utfencode) {
                        // string is converted to htmlentities and sanitized
                        $replace = charset_decode($res[2],$replace);
                    } elseif ($htmlsave) {
                        // string is not converted, but still sanitized
                        $replace = sm_encode_html_special_chars($replace);
                    }
                    $ret.= $replace;
                    break;
                case 'Q':
                    $replace = str_replace('_', ' ', $res[4]);
                    $replace = preg_replace_callback('/=([0-9a-f]{2})/i',
                                             (check_php_version(5, 3, 0)
                                              ? function($matches) { return chr(hexdec($matches[1])); }
                                              : create_function ('$matches', 'return chr(hexdec($matches[1]));')
                                             ),
                                             $replace);
                    if ($can_be_encoded) {
                        // string is converted from one charset to another. sanitizing depends on $htmlsave
                        $replace = charset_convert($res[2], $replace,$default_charset,$htmlsave);
                    } elseif ($utfencode) {
                        // string is converted to html entities and sanitized
                        $replace = charset_decode($res[2], $replace);
                    } elseif ($htmlsave) {
                        // string is not converted, but still sanizited
                        $replace = sm_encode_html_special_chars($replace);
                    }
                    $ret .= $replace;
                    break;
                default:
                    break;
            }
            $chunk = $res[5];
            $encoded = true;
        }
        if (!$encoded) {
            if ($htmlsave) {
                $ret .= '&#32;';
            } else {
                $ret .= ' ';
            }
        }

        // It is possible to slip XSS in here when a header has encoded content followed by unecoded malicious content --- this test was written long ago, but because the leftover $chunk has not been classified or handled in any way, we can't assume it is safe to include as-is.... We'll assume the person who wrote this if() would agree and didn't mean to accidentally allow such and that what they meant was the following corrected line:
        // if (!$encoded && $htmlsave) {
        if ($htmlsave) {
            $ret .= sm_encode_html_special_chars($chunk);
        } else {
            $ret .= $chunk;
        }
        ++$i;
    }
    /* remove the first added space */
    if ($ret) {
        if ($htmlsave) {
            $ret = substr($ret,5);
        } else {
            $ret = substr($ret,1);
        }
    }

    return $ret;
}

/**
 * Encodes header as quoted-printable
 *
 * Encode a string according to RFC 1522 for use in headers if it
 * contains 8-bit characters or anything that looks like it should
 * be encoded.
 */
function encodeHeader ($string) {
    global $default_charset, $languages, $squirrelmail_language;

    if (isset($languages[$squirrelmail_language]['XTRA_CODE']) &&
            function_exists($languages[$squirrelmail_language]['XTRA_CODE'])) {
        return  $languages[$squirrelmail_language]['XTRA_CODE']('encodeheader', $string);
    }

    // Use B encoding for multibyte charsets
    $mb_charsets = array('utf-8','big5','gb2313','euc-kr');
    if (in_array($default_charset,$mb_charsets) &&
        in_array($default_charset,sq_mb_list_encodings()) &&
        sq_is8bit($string)) {
        return encodeHeaderBase64($string,$default_charset);
    } elseif (in_array($default_charset,$mb_charsets) &&
              sq_is8bit($string) &&
              ! in_array($default_charset,sq_mb_list_encodings())) {
        // Add E_USER_NOTICE error here (can cause 'Cannot add header information' warning in compose.php)
        // trigger_error('encodeHeader: Multibyte character set unsupported by mbstring extension.',E_USER_NOTICE);
    }

    // Encode only if the string contains 8-bit characters or =?
    $j = strlen($string);
    $max_l = 75 - strlen($default_charset) - 7;
    $aRet = array();
    $ret = '';
    $iEncStart = $enc_init = false;
    $cur_l = $iOffset = 0;
    for($i = 0; $i < $j; ++$i) {
        switch($string[$i])
        {
            case '"':
            case '=':
            case '<':
            case '>':
            case ',':
            case '?':
            case '_':
                if ($iEncStart === false) {
                    $iEncStart = $i;
                }
                $cur_l+=3;
                if ($cur_l > ($max_l-2)) {
                    /* if there is an stringpart that doesn't need encoding, add it */
                    $aRet[] = substr($string,$iOffset,$iEncStart-$iOffset);
                    $aRet[] = "=?$default_charset?Q?$ret?=";
                    $iOffset = $i;
                    $cur_l = 0;
                    $ret = '';
                    $iEncStart = false;
                } else {
                    $ret .= sprintf("=%02X",ord($string[$i]));
                }
                break;
            case '(':
            case ')':
                if ($iEncStart !== false) {
                    $aRet[] = substr($string,$iOffset,$iEncStart-$iOffset);
                    $aRet[] = "=?$default_charset?Q?$ret?=";
                    $iOffset = $i;
                    $cur_l = 0;
                    $ret = '';
                    $iEncStart = false;
                }
                break;
            case ' ':
                if ($iEncStart !== false) {
                    $cur_l++;
                    if ($cur_l > $max_l) {
                        $aRet[] = substr($string,$iOffset,$iEncStart-$iOffset);
                        $aRet[] = "=?$default_charset?Q?$ret?=";
                        $iOffset = $i;
                        $cur_l = 0;
                        $ret = '';
                        $iEncStart = false;
                    } else {
                        $ret .= '_';
                    }
                }
                break;
            default:
                $k = ord($string[$i]);
                if ($k > 126) {
                    if ($iEncStart === false) {
                        // do not start encoding in the middle of a string, also take the rest of the word.
                        $sLeadString = substr($string,0,$i);
                        $aLeadString = explode(' ',$sLeadString);
                        $sToBeEncoded = array_pop($aLeadString);
                        $iEncStart = $i - strlen($sToBeEncoded);
                        $ret .= $sToBeEncoded;
                        $cur_l += strlen($sToBeEncoded);
                    }
                    $cur_l += 3;
                    /* first we add the encoded string that reached it's max size */
                    if ($cur_l > ($max_l-2)) {
                        $aRet[] = substr($string,$iOffset,$iEncStart-$iOffset);
                        $aRet[] = "=?$default_charset?Q?$ret?= "; /* the next part is also encoded => separate by space */
                        $cur_l = 3;
                        $ret = '';
                        $iOffset = $i;
                        $iEncStart = $i;
                    }
                    $enc_init = true;
                    $ret .= sprintf("=%02X", $k);
                } else {
                    if ($iEncStart !== false) {
                        $cur_l++;
                        if ($cur_l > $max_l) {
                            $aRet[] = substr($string,$iOffset,$iEncStart-$iOffset);
                            $aRet[] = "=?$default_charset?Q?$ret?=";
                            $iEncStart = false;
                            $iOffset = $i;
                            $cur_l = 0;
                            $ret = '';
                        } else {
                            $ret .= $string[$i];
                        }
                    }
                }
                break;
        }
    }

    if ($enc_init) {
        if ($iEncStart !== false) {
            $aRet[] = substr($string,$iOffset,$iEncStart-$iOffset);
            $aRet[] = "=?$default_charset?Q?$ret?=";
        } else {
            $aRet[] = substr($string,$iOffset);
        }
        $string = implode('',$aRet);
    }
    return $string;
}

/**
 * Encodes string according to rfc2047 B encoding header formating rules
 *
 * It is recommended way to encode headers with character sets that store
 * symbols in more than one byte.
 *
 * Function requires mbstring support. If required mbstring functions are missing,
 * function returns false and sets E_USER_WARNING level error message.
 *
 * Minimal requirements - php 4.0.6 with mbstring extension. Please note,
 * that mbstring functions will generate E_WARNING errors, if unsupported
 * character set is used. mb_encode_mimeheader function provided by php
 * mbstring extension is not used in order to get better control of header
 * encoding.
 *
 * Used php code functions - function_exists(), trigger_error(), strlen()
 * (is used with charset names and base64 strings). Used php mbstring
 * functions - mb_strlen and mb_substr.
 *
 * Related documents: rfc 2045 (BASE64 encoding), rfc 2047 (mime header
 * encoding), rfc 2822 (header folding)
 *
 * @param string $string header string that must be encoded
 * @param string $charset character set. Must be supported by mbstring extension.
 * Use sq_mb_list_encodings() to detect supported charsets.
 * @return string string encoded according to rfc2047 B encoding formating rules
 * @since 1.5.1 and 1.4.6
 */
function encodeHeaderBase64($string,$charset) {
    /**
     * Check mbstring function requirements.
     */
    if (! function_exists('mb_strlen') ||
        ! function_exists('mb_substr')) {
        // set E_USER_WARNING
        trigger_error('encodeHeaderBase64: Required mbstring functions are missing.',E_USER_WARNING);
        // return false
        return false;
    }

    // initial return array
    $aRet = array();

    /**
     * header length = 75 symbols max (same as in encodeHeader)
     * remove $charset length
     * remove =? ? ?= (5 chars)
     * remove 2 more chars (\r\n ?)
     */
    $iMaxLength = 75 - strlen($charset) - 7;

    // set first character position
    $iStartCharNum = 0;

    // loop through all characters. count characters and not bytes.
    for ($iCharNum=1; $iCharNum<=mb_strlen($string,$charset); $iCharNum++) {
        // encode string from starting character to current character.
        $encoded_string = base64_encode(mb_substr($string,$iStartCharNum,$iCharNum-$iStartCharNum,$charset));

        // Check encoded string length
        if(strlen($encoded_string)>$iMaxLength) {
            // if string exceeds max length, reduce number of encoded characters and add encoded string part to array
            $aRet[] = base64_encode(mb_substr($string,$iStartCharNum,$iCharNum-$iStartCharNum-1,$charset));

            // set new starting character
            $iStartCharNum = $iCharNum-1;

            // encode last char (in case it is last character in string)
            $encoded_string = base64_encode(mb_substr($string,$iStartCharNum,$iCharNum-$iStartCharNum,$charset));
        } // if string is shorter than max length - add next character
    }

    // add last encoded string to array
    $aRet[] = $encoded_string;

    // set initial return string
    $sRet = '';

    // loop through encoded strings
    foreach($aRet as $string) {
        // TODO: Do we want to control EOL (end-of-line) marker
        if ($sRet!='') $sRet.= " ";

        // add header tags and encoded string to return string
        $sRet.= '=?'.$charset.'?B?'.$string.'?=';
    }

    return $sRet;
}

/* This function trys to locate the entity_id of a specific mime element */
function find_ent_id($id, $message) {
    for ($i = 0, $ret = ''; $ret == '' && $i < count($message->entities); $i++) {
        if ($message->entities[$i]->header->type0 == 'multipart')  {
            $ret = find_ent_id($id, $message->entities[$i]);
        } else {
            if (strcasecmp($message->entities[$i]->header->id, $id) == 0) {
//                if (sq_check_save_extension($message->entities[$i])) {
                return $message->entities[$i]->entity_id;
//                }
            } elseif (!empty($message->entities[$i]->header->parameters['name'])) {
                /**
                 * This is part of a fix for Outlook Express 6.x generating
                 * cid URLs without creating content-id headers
                 * @@JA - 20050207
                 */
                if (strcasecmp($message->entities[$i]->header->parameters['name'], $id) == 0) {
                    return $message->entities[$i]->entity_id;
                }
            }
        }
    }
    return $ret;
}

function sq_check_save_extension($message) {
    $filename = $message->getFilename();
    $ext = substr($filename, strrpos($filename,'.')+1);
    $save_extensions = array('jpg','jpeg','gif','png','bmp');
    return in_array($ext, $save_extensions);
}


/**
 ** HTMLFILTER ROUTINES
 */

/**
 * This function checks attribute values for entity-encoded values
 * and returns them translated into 8-bit strings so we can run
 * checks on them.
 *
 * @param  $attvalue A string to run entity check against.
 * @return           Nothing, modifies a reference value.
 */
function sq_defang(&$attvalue){
    $me = 'sq_defang';
    /**
     * Skip this if there aren't ampersands or backslashes.
     */
    if (strpos($attvalue, '&') === false
        && strpos($attvalue, '\\') === false){
        return;
    }
    $m = false;
    do {
        $m = false;
        $m = $m || sq_deent($attvalue, '/\&#0*(\d+);*/s');
        $m = $m || sq_deent($attvalue, '/\&#x0*((\d|[a-f])+);*/si', true);
        $m = $m || sq_deent($attvalue, '/\\\\(\d+)/s', true);
    } while ($m == true);
    $attvalue = stripslashes($attvalue);
}

/**
 * Kill any tabs, newlines, or carriage returns. Our friends the
 * makers of the browser with 95% market value decided that it'd
 * be funny to make "java[tab]script" be just as good as "javascript".
 *
 * @param  attvalue  The attribute value before extraneous spaces removed.
 * @return attvalue  Nothing, modifies a reference value.
 */
function sq_unspace(&$attvalue){
    $me = 'sq_unspace';
    if (strcspn($attvalue, "\t\r\n\0 ") != strlen($attvalue)){
        $attvalue = str_replace(Array("\t", "\r", "\n", "\0", " "),
                                Array('',   '',   '',   '',   ''), $attvalue);
    }
}

/**
 * Translate all dangerous Unicode or Shift_JIS characters which are accepted by
 * IE as regular characters.
 *
 * @param  attvalue  The attribute value before dangerous characters are translated.
 * @return attvalue  Nothing, modifies a reference value.
 * @author Marc Groot Koerkamp.
 */
function sq_fixIE_idiocy(&$attvalue) {
    // remove NUL
    $attvalue = str_replace("\0", "", $attvalue);
    // remove comments
    $attvalue = preg_replace("/(\/\*.*?\*\/)/","",$attvalue);

    // IE has the evil habit of accepting every possible value for the attribute expression.
    // The table below contains characters which are parsed by IE if they are used in the "expression"
    // attribute value.
    $aDangerousCharsReplacementTable = array(
                        array('&#x029F;', '&#0671;' ,/* L UNICODE IPA Extension */
                              '&#x0280;', '&#0640;' ,/* R UNICODE IPA Extension */
                              '&#x0274;', '&#0628;' ,/* N UNICODE IPA Extension */
                              '&#xFF25;', '&#65317;' ,/* Unicode FULLWIDTH LATIN CAPITAL LETTER E */
                              '&#xFF45;', '&#65349;' ,/* Unicode FULLWIDTH LATIN SMALL LETTER E */
                              '&#xFF38;', '&#65336;',/* Unicode FULLWIDTH LATIN CAPITAL LETTER X */
                              '&#xFF58;', '&#65368;',/* Unicode FULLWIDTH LATIN SMALL LETTER X */
                              '&#xFF30;', '&#65328;',/* Unicode FULLWIDTH LATIN CAPITAL LETTER P */
                              '&#xFF50;', '&#65360;',/* Unicode FULLWIDTH LATIN SMALL LETTER P */
                              '&#xFF32;', '&#65330;',/* Unicode FULLWIDTH LATIN CAPITAL LETTER R */
                              '&#xFF52;', '&#65362;',/* Unicode FULLWIDTH LATIN SMALL LETTER R */
                              '&#xFF33;', '&#65331;',/* Unicode FULLWIDTH LATIN CAPITAL LETTER S */
                              '&#xFF53;', '&#65363;',/* Unicode FULLWIDTH LATIN SMALL LETTER S */
                              '&#xFF29;', '&#65321;',/* Unicode FULLWIDTH LATIN CAPITAL LETTER I */
                              '&#xFF49;', '&#65353;',/* Unicode FULLWIDTH LATIN SMALL LETTER I */
                              '&#xFF2F;', '&#65327;',/* Unicode FULLWIDTH LATIN CAPITAL LETTER O */
                              '&#xFF4F;', '&#65359;',/* Unicode FULLWIDTH LATIN SMALL LETTER O */
                              '&#xFF2E;', '&#65326;',/* Unicode FULLWIDTH LATIN CAPITAL LETTER N */
                              '&#xFF4E;', '&#65358;',/* Unicode FULLWIDTH LATIN SMALL LETTER N */
                              '&#xFF2C;', '&#65324;',/* Unicode FULLWIDTH LATIN CAPITAL LETTER L */
                              '&#xFF4C;', '&#65356;',/* Unicode FULLWIDTH LATIN SMALL LETTER L */
                              '&#xFF35;', '&#65333;',/* Unicode FULLWIDTH LATIN CAPITAL LETTER U */
                              '&#xFF55;', '&#65365;',/* Unicode FULLWIDTH LATIN SMALL LETTER U */
                              '&#x207F;', '&#8319;' ,/* Unicode SUPERSCRIPT LATIN SMALL LETTER N */
                              "\xEF\xBC\xA5", /* Shift JIS FULLWIDTH LATIN CAPITAL LETTER E */   // in unicode this is some Chinese char range
                              "\xEF\xBD\x85", /* Shift JIS FULLWIDTH LATIN SMALL LETTER E */
                              "\xEF\xBC\xB8", /* Shift JIS FULLWIDTH LATIN CAPITAL LETTER X */
                              "\xEF\xBD\x98", /* Shift JIS FULLWIDTH LATIN SMALL LETTER X */
                              "\xEF\xBC\xB0", /* Shift JIS FULLWIDTH LATIN CAPITAL LETTER P */
                              "\xEF\xBD\x90", /* Shift JIS FULLWIDTH LATIN SMALL LETTER P */
                              "\xEF\xBC\xB2", /* Shift JIS FULLWIDTH LATIN CAPITAL LETTER R */
                              "\xEF\xBD\x92", /* Shift JIS FULLWIDTH LATIN SMALL LETTER R */
                              "\xEF\xBC\xB3", /* Shift JIS FULLWIDTH LATIN CAPITAL LETTER S */
                              "\xEF\xBD\x93", /* Shift JIS FULLWIDTH LATIN SMALL LETTER S */
                              "\xEF\xBC\xA9", /* Shift JIS FULLWIDTH LATIN CAPITAL LETTER I */
                              "\xEF\xBD\x89", /* Shift JIS FULLWIDTH LATIN SMALL LETTER I */
                              "\xEF\xBC\xAF", /* Shift JIS FULLWIDTH LATIN CAPITAL LETTER O */
                              "\xEF\xBD\x8F", /* Shift JIS FULLWIDTH LATIN SMALL LETTER O */
                              "\xEF\xBC\xAE", /* Shift JIS FULLWIDTH LATIN CAPITAL LETTER N */
                              "\xEF\xBD\x8E", /* Shift JIS FULLWIDTH LATIN SMALL LETTER N */
                              "\xEF\xBC\xAC", /* Shift JIS FULLWIDTH LATIN CAPITAL LETTER L */
                              "\xEF\xBD\x8C", /* Shift JIS FULLWIDTH LATIN SMALL LETTER L */
                              "\xEF\xBC\xB5", /* Shift JIS FULLWIDTH LATIN CAPITAL LETTER U */
                              "\xEF\xBD\x95", /* Shift JIS FULLWIDTH LATIN SMALL LETTER U */
                              "\xE2\x81\xBF", /* Shift JIS FULLWIDTH SUPERSCRIPT N */
                              "\xCA\x9F", /* L UNICODE IPA Extension */
                              "\xCA\x80", /* R UNICODE IPA Extension */
                              "\xC9\xB4"),  /* N UNICODE IPA Extension */
                       array('l', 'l', 'r','r','n','n',
                             'E','E','e','e','X','X','x','x','P','P','p','p','R','R','r','r','S','S','s','s','I','I',
                             'i','i','O','O','o','o','N','N','n','n','L','L','l','l','U','U','u','u','n','n',
                             'E','e','X','x','P','p','R','r','S','s','I','i','O','o','N','n','L','l','U','u','n','l','r','n'));
    $attvalue = str_replace($aDangerousCharsReplacementTable[0],$aDangerousCharsReplacementTable[1],$attvalue);

    // Escapes are useful for special characters like "{}[]()'&. In other cases they are
    // used for XSS.
    $attvalue = preg_replace("/(\\\\)([a-zA-Z]{1})/",'$2',$attvalue);
}

/**
 * This function returns the final tag out of the tag name, an array
 * of attributes, and the type of the tag. This function is called by
 * sq_sanitize internally.
 *
 * @param  $tagname  the name of the tag.
 * @param  $attary   the array of attributes and their values
 * @param  $tagtype  The type of the tag (see in comments).
 * @return           a string with the final tag representation.
 */
function sq_tagprint($tagname, $attary, $tagtype){
    $me = 'sq_tagprint';

    if ($tagtype == 2){
        $fulltag = '</' . $tagname . '>';
    } else {
        $fulltag = '<' . $tagname;
        if (is_array($attary) && sizeof($attary)){
            $atts = Array();
            foreach ($attary as $attname => $attvalue){
                array_push($atts, "$attname=$attvalue");
            }
            $fulltag .= ' ' . join(" ", $atts);
        }
        if ($tagtype == 3){
            $fulltag .= ' /';
        }
        $fulltag .= '>';
    }
    return $fulltag;
}

/**
 * A small helper function to use with array_walk. Modifies a by-ref
 * value and makes it lowercase.
 *
 * @param  $val a value passed by-ref.
 * @return      void since it modifies a by-ref value.
 */
function sq_casenormalize(&$val){
    $val = strtolower($val);
}

/**
 * This function skips any whitespace from the current position within
 * a string and to the next non-whitespace value.
 *
 * @param  $body   the string
 * @param  $offset the offset within the string where we should start
 *                 looking for the next non-whitespace character.
 * @return         the location within the $body where the next
 *                 non-whitespace char is located.
 */
function sq_skipspace($body, $offset){
    $me = 'sq_skipspace';
    preg_match('/^(\s*)/s', substr($body, $offset), $matches);
    if (!empty($matches[1])){
        $offset += strlen($matches[1]);
    }
    return $offset;
}

/**
 * This function looks for the next character within a string.  It's
 * really just a glorified "strpos", except it catches if failures
 * nicely.
 *
 * @param  $body   The string to look for needle in.
 * @param  $offset Start looking from this position.
 * @param  $needle The character/string to look for.
 * @return         location of the next occurance of the needle, or
 *                 strlen($body) if needle wasn't found.
 */
function sq_findnxstr($body, $offset, $needle){
    $me  = 'sq_findnxstr';
    $pos = strpos($body, $needle, $offset);
    if ($pos === FALSE){
        $pos = strlen($body);
    }
    return $pos;
}

/**
 * This function takes a PCRE-style regexp and tries to match it
 * within the string.
 *
 * @param  $body   The string to look for needle in.
 * @param  $offset Start looking from here.
 * @param  $reg    A PCRE-style regex to match.
 * @return         Returns a false if no matches found, or an array
 *                 with the following members:
 *                 - integer with the location of the match within $body
 *                 - string with whatever content between offset and the match
 *                 - string with whatever it is we matched
 */
function sq_findnxreg($body, $offset, $reg){
    $me = 'sq_findnxreg';
    $matches = Array();
    $retarr = Array();
    preg_match("%^(.*?)($reg)%si", substr($body, $offset), $matches);
    if (!isset($matches[0]) || !$matches[0]){
        $retarr = false;
    } else {
        $retarr[0] = $offset + strlen($matches[1]);
        $retarr[1] = $matches[1];
        $retarr[2] = $matches[2];
    }
    return $retarr;
}

/**
 * This function looks for the next tag.
 *
 * @param  $body   String where to look for the next tag.
 * @param  $offset Start looking from here.
 * @return         false if no more tags exist in the body, or
 *                 an array with the following members:
 *                 - string with the name of the tag
 *                 - array with attributes and their values
 *                 - integer with tag type (1, 2, or 3)
 *                 - integer where the tag starts (starting "<")
 *                 - integer where the tag ends (ending ">")
 *                 first three members will be false, if the tag is invalid.
 */
function sq_getnxtag($body, $offset){
    $me = 'sq_getnxtag';
    if ($offset > strlen($body)){
        return false;
    }
    $lt = sq_findnxstr($body, $offset, "<");
    if ($lt == strlen($body)){
        return false;
    }
    /**
     * We are here:
     * blah blah <tag attribute="value">
     * \---------^
     */
    $pos = sq_skipspace($body, $lt+1);
    if ($pos >= strlen($body)){
        return Array(false, false, false, $lt, strlen($body));
    }
    /**
     * There are 3 kinds of tags:
     * 1. Opening tag, e.g.:
     *    <a href="blah">
     * 2. Closing tag, e.g.:
     *    </a>
     * 3. XHTML-style content-less tag, e.g.:
     *    <img src="blah" />
     */
    $tagtype = false;
    switch (substr($body, $pos, 1)){
        case '/':
            $tagtype = 2;
            $pos++;
            break;
        case '!':
            /**
             * A comment or an SGML declaration.
             */
            if (substr($body, $pos+1, 2) == "--"){
                $gt = strpos($body, "-->", $pos);
                if ($gt === false){
                    $gt = strlen($body);
                } else {
                    $gt += 2;
                }
                return Array(false, false, false, $lt, $gt);
            } else {
                $gt = sq_findnxstr($body, $pos, ">");
                return Array(false, false, false, $lt, $gt);
            }
            break;
        default:
            /**
             * Assume tagtype 1 for now. If it's type 3, we'll switch values
             * later.
             */
            $tagtype = 1;
            break;
    }

    $tag_start = $pos;
    $tagname = '';
    /**
     * Look for next [\W-_], which will indicate the end of the tag name.
     */
    $regary = sq_findnxreg($body, $pos, "[^\w\-_]");
    if ($regary == false){
        return Array(false, false, false, $lt, strlen($body));
    }
    list($pos, $tagname, $match) = $regary;
    $tagname = strtolower($tagname);

    /**
     * $match can be either of these:
     * '>'  indicating the end of the tag entirely.
     * '\s' indicating the end of the tag name.
     * '/'  indicating that this is type-3 xhtml tag.
     *
     * Whatever else we find there indicates an invalid tag.
     */
    switch ($match){
        case '/':
            /**
             * This is an xhtml-style tag with a closing / at the
             * end, like so: <img src="blah" />. Check if it's followed
             * by the closing bracket. If not, then this tag is invalid
             */
            if (substr($body, $pos, 2) == "/>"){
                $pos++;
                $tagtype = 3;
            } else {
                $gt = sq_findnxstr($body, $pos, ">");
                $retary = Array(false, false, false, $lt, $gt);
                return $retary;
            }
        case '>':
            return Array($tagname, false, $tagtype, $lt, $pos);
            break;
        default:
            /**
             * Check if it's whitespace
             */
            if (!preg_match('/\s/', $match)){
                /**
                 * This is an invalid tag! Look for the next closing ">".
                 */
                $gt = sq_findnxstr($body, $lt, ">");
                return Array(false, false, false, $lt, $gt);
            }
            break;
    }

    /**
     * At this point we're here:
     * <tagname  attribute='blah'>
     * \-------^
     *
     * At this point we loop in order to find all attributes.
     */
    $attname = '';
    $atttype = false;
    $attary = Array();

    while ($pos <= strlen($body)){
        $pos = sq_skipspace($body, $pos);
        if ($pos == strlen($body)){
            /**
             * Non-closed tag.
             */
            return Array(false, false, false, $lt, $pos);
        }
        /**
         * See if we arrived at a ">" or "/>", which means that we reached
         * the end of the tag.
         */
        $matches = Array();
        if (preg_match("%^(\s*)(>|/>)%s", substr($body, $pos), $matches)) {
            /**
             * Yep. So we did.
             */
            $pos += strlen($matches[1]);
            if ($matches[2] == "/>"){
                $tagtype = 3;
                $pos++;
            }
            return Array($tagname, $attary, $tagtype, $lt, $pos);
        }

        /**
         * There are several types of attributes, with optional
         * [:space:] between members.
         * Type 1:
         *   attrname[:space:]=[:space:]'CDATA'
         * Type 2:
         *   attrname[:space:]=[:space:]"CDATA"
         * Type 3:
         *   attr[:space:]=[:space:]CDATA
         * Type 4:
         *   attrname
         *
         * We leave types 1 and 2 the same, type 3 we check for
         * '"' and convert to "&quot" if needed, then wrap in
         * double quotes. Type 4 we convert into:
         * attrname="yes".
         */
        $regary = sq_findnxreg($body, $pos, "[^:\w\-_]");
        if ($regary == false){
            /**
             * Looks like body ended before the end of tag.
             */
            return Array(false, false, false, $lt, strlen($body));
        }
        list($pos, $attname, $match) = $regary;
        $attname = strtolower($attname);
        /**
         * We arrived at the end of attribute name. Several things possible
         * here:
         * '>'  means the end of the tag and this is attribute type 4
         * '/'  if followed by '>' means the same thing as above
         * '\s' means a lot of things -- look what it's followed by.
         *      anything else means the attribute is invalid.
         */
        switch($match){
            case '/':
                /**
                 * This is an xhtml-style tag with a closing / at the
                 * end, like so: <img src="blah" />. Check if it's followed
                 * by the closing bracket. If not, then this tag is invalid
                 */
                if (substr($body, $pos, 2) == "/>"){
                    $pos++;
                    $tagtype = 3;
                } else {
                    $gt = sq_findnxstr($body, $pos, ">");
                    $retary = Array(false, false, false, $lt, $gt);
                    return $retary;
                }
            case '>':
                $attary[$attname] = '"yes"';
                return Array($tagname, $attary, $tagtype, $lt, $pos);
                break;
            default:
                /**
                 * Skip whitespace and see what we arrive at.
                 */
                $pos = sq_skipspace($body, $pos);
                $char = substr($body, $pos, 1);
                /**
                 * Two things are valid here:
                 * '=' means this is attribute type 1 2 or 3.
                 * \w means this was attribute type 4.
                 * anything else we ignore and re-loop. End of tag and
                 * invalid stuff will be caught by our checks at the beginning
                 * of the loop.
                 */
                if ($char == "="){
                    $pos++;
                    $pos = sq_skipspace($body, $pos);
                    /**
                     * Here are 3 possibilities:
                     * "'"  attribute type 1
                     * '"'  attribute type 2
                     * everything else is the content of tag type 3
                     */
                    $quot = substr($body, $pos, 1);
                    if ($quot == "'"){
                        $regary = sq_findnxreg($body, $pos+1, "\'");
                        if ($regary == false){
                            return Array(false, false, false, $lt, strlen($body));
                        }
                        list($pos, $attval, $match) = $regary;
                        $pos++;
                        $attary[$attname] = "'" . $attval . "'";
                    } else if ($quot == '"'){
                        $regary = sq_findnxreg($body, $pos+1, '\"');
                        if ($regary == false){
                            return Array(false, false, false, $lt, strlen($body));
                        }
                        list($pos, $attval, $match) = $regary;
                        $pos++;
                        $attary[$attname] = '"' . $attval . '"';
                    } else {
                        /**
                         * These are hateful. Look for \s, or >.
                         */
                        $regary = sq_findnxreg($body, $pos, "[\s>]");
                        if ($regary == false){
                            return Array(false, false, false, $lt, strlen($body));
                        }
                        list($pos, $attval, $match) = $regary;
                        /**
                         * If it's ">" it will be caught at the top.
                         */
                        $attval = preg_replace("/\"/s", "&quot;", $attval);
                        $attary[$attname] = '"' . $attval . '"';
                    }
                } else if (preg_match("|[\w/>]|", $char)) {
                    /**
                     * That was attribute type 4.
                     */
                    $attary[$attname] = '"yes"';
                } else {
                    /**
                     * An illegal character. Find next '>' and return.
                     */
                    $gt = sq_findnxstr($body, $pos, ">");
                    return Array(false, false, false, $lt, $gt);
                }
                break;
        }
    }
    /**
     * The fact that we got here indicates that the tag end was never
     * found. Return invalid tag indication so it gets stripped.
     */
    return Array(false, false, false, $lt, strlen($body));
}

/**
 * Translates entities into literal values so they can be checked.
 *
 * @param $attvalue the by-ref value to check.
 * @param $regex    the regular expression to check against.
 * @param $hex      whether the entites are hexadecimal.
 * @return          True or False depending on whether there were matches.
 */
function sq_deent(&$attvalue, $regex, $hex=false){
    $me = 'sq_deent';
    $ret_match = false;
    preg_match_all($regex, $attvalue, $matches);
    if (is_array($matches) && sizeof($matches[0]) > 0){
        $repl = Array();
        for ($i = 0; $i < sizeof($matches[0]); $i++){
            $numval = $matches[1][$i];
            if ($hex){
                $numval = hexdec($numval);
            }
            $repl[$matches[0][$i]] = chr($numval);
        }
        $attvalue = strtr($attvalue, $repl);
        return true;
    } else {
        return false;
    }
}

/**
 * This function runs various checks against the attributes.
 *
 * @param  $tagname         String with the name of the tag.
 * @param  $attary          Array with all tag attributes.
 * @param  $rm_attnames     See description for sq_sanitize
 * @param  $bad_attvals     See description for sq_sanitize
 * @param  $add_attr_to_tag See description for sq_sanitize
 * @param  $message         message object
 * @param  $id              message id
 * @param  $mailbox         mailbox
 * @return                  Array with modified attributes.
 */
function sq_fixatts($tagname,
                    $attary,
                    $rm_attnames,
                    $bad_attvals,
                    $add_attr_to_tag,
                    $message,
                    $id,
                    $mailbox
                    ){
    $me = 'sq_fixatts';
    foreach ($attary as $attname => $attvalue){
        /**
         * See if this attribute should be removed.
         */
        foreach ($rm_attnames as $matchtag=>$matchattrs){
            if (preg_match($matchtag, $tagname)){
                foreach ($matchattrs as $matchattr){
                    if (preg_match($matchattr, $attname)){
                        unset($attary[$attname]);
                        continue;
                    }
                }
            }
        }

        /**
         * Workaround for IE quirks
         */
        sq_fixIE_idiocy($attvalue);

        /**
         * Remove any backslashes, entities, and extraneous whitespace.
         */
        $oldattvalue = $attvalue;
        sq_defang($attvalue);
        if ($attname == 'style' && $attvalue !== $oldattvalue) {
            // entities are used in the attribute value. In 99% of the cases it's there as XSS
            // i.e.<div style="{ left:exp&#x0280;essio&#x0274;( alert('XSS') ) }">
            $attvalue = "idiocy";
            $attary[$attname] = $attvalue;
        }
        sq_unspace($attvalue);

        /**
         * Now let's run checks on the attvalues.
         * I don't expect anyone to comprehend this. If you do,
         * get in touch with me so I can drive to where you live and
         * shake your hand personally. :)
         */
        foreach ($bad_attvals as $matchtag=>$matchattrs){
            if (preg_match($matchtag, $tagname)){
                foreach ($matchattrs as $matchattr=>$valary){
                    if (preg_match($matchattr, $attname)){
                        /**
                         * There are two arrays in valary.
                         * First is matches.
                         * Second one is replacements
                         */
                        list($valmatch, $valrepl) = $valary;
                        $newvalue =
                            preg_replace($valmatch, $valrepl, $attvalue);
                        if ($newvalue != $attvalue){
                            $attary[$attname] = $newvalue;
                            $attvalue = $newvalue;
                        }
                    }
                }
            }
        }
        if ($attname == 'style') {
            if (preg_match('/[\0-\37\200-\377]+/',$attvalue)) {
                // 8bit and control characters in style attribute values can be used for XSS, remove them
                $attary[$attname] = '"disallowed character"';
            }
            preg_match_all("/url\s*\((.+)\)/si",$attvalue,$aMatch);
            if (count($aMatch)) {
                foreach($aMatch[1] as $sMatch) {
                    // url value
                    $urlvalue = $sMatch;
                    sq_fix_url($attname, $urlvalue, $message, $id, $mailbox,"'");
                    $attary[$attname] = str_replace($sMatch,$urlvalue,$attvalue);
                }
            }
        }
        /**
         * Use white list based filtering on attributes which can contain url's
         */
        else if ($attname == 'href' || $attname == 'xlink:href' || $attname == 'src'
              || $attname == 'poster' || $attname == 'formaction'
              || $attname == 'background' || $attname == 'action') {
            sq_fix_url($attname, $attvalue, $message, $id, $mailbox);
            $attary[$attname] = $attvalue;
        }
    }
    /**
     * See if we need to append any attributes to this tag.
     */
    foreach ($add_attr_to_tag as $matchtag=>$addattary){
        if (preg_match($matchtag, $tagname)){
            $attary = array_merge($attary, $addattary);
        }
    }
    return $attary;
}

/**
 * This function filters url's
 *
 * @param  $attvalue        String with attribute value to filter
 * @param  $message         message object
 * @param  $id               message id
 * @param  $mailbox         mailbox
 * @param  $sQuote          quoting characters around url's
 */
function sq_fix_url($attname, &$attvalue, $message, $id, $mailbox,$sQuote = '"') {
    $attvalue = trim($attvalue);
    if ($attvalue && ($attvalue[0] =='"'|| $attvalue[0] == "'")) {
        // remove the double quotes
        $sQuote = $attvalue[0];
        $attvalue = trim(substr($attvalue,1,-1));
    }

    // If there's no "view_unsafe_images" variable in the URL, turn unsafe
    // images off by default.
    if( !sqgetGlobalVar('view_unsafe_images', $view_unsafe_images, SQ_GET) ) {
        $view_unsafe_images = false;
    }

    global $use_transparent_security_image;
    if ($use_transparent_security_image) $secremoveimg = '../images/spacer.png';
    else $secremoveimg = '../images/' . _("sec_remove_eng.png");

    /**
     * Replace empty src tags with the blank image.  src is only used
     * for frames, images, and image inputs.  Doing a replace should
     * not affect them working as should be, however it will stop
     * IE from being kicked off when src for img tags are not set
     */
    if ($attvalue == '') {
        $attvalue = '"' . SM_PATH . 'images/blank.png"';
    } else {
        // first, disallow 8 bit characters and control characters
        if (preg_match('/[\0-\37\200-\377]+/',$attvalue)) {
            switch ($attname) {
                case 'href':
                    $attvalue = $sQuote . 'http://invalid-stuff-detected.example.com' . $sQuote;
                    break;
                default:
                    $attvalue = $sQuote . SM_PATH . 'images/blank.png'. $sQuote;
                    break;
            }
        } else {
            $aUrl = parse_url($attvalue);
            if (isset($aUrl['scheme'])) {
                switch(strtolower($aUrl['scheme'])) {
                    case 'mailto':
                    case 'http':
                    case 'https':
                    case 'ftp':
                        if ($attname != 'href') {
                            if ($view_unsafe_images == false) {
                                $attvalue = $sQuote . $secremoveimg . $sQuote;
                            } else {
                                if (isset($aUrl['path'])) {

                                    // No one has been able to show that image URIs
                                    // can be exploited, so for now, no restrictions
                                    // are made at all.  If this proves to be a problem,
                                    // the commented-out code below can be of help.
                                    // (One consideration is that I see nothing in this
                                    // function that specifically says that we will
                                    // only ever arrive here when inspecting an image
                                    // tag, although that does seem to be the end
                                    // result - e.g., <script src="..."> where malicious
                                    // image URIs are in fact a problem are already
                                    // filtered out elsewhere.
                                    /* ---------------------------------
                                    // validate image extension.
                                    $ext = strtolower(substr($aUrl['path'],strrpos($aUrl['path'],'.')));
                                    if (!in_array($ext,array('.jpeg','.jpg','xjpeg','.gif','.bmp','.jpe','.png','.xbm'))) {
                                        // If URI is to something other than
                                        // a regular image file, get the contents
                                        // and try to see if it is an image.
                                        // Don't use Fileinfo (finfo_file()) because
                                        // we'd need to make the admin configure the
                                        // location of the magic.mime file (FIXME: add finfo_file() support later?)
                                        //
                                        $mime_type = '';
                                        if (function_exists('mime_content_type')
                                         && ($FILE = @fopen($attvalue, 'rb', FALSE))) {

                                            // fetch file
                                            //
                                            $file_contents = '';
                                            while (!feof($FILE)) {
                                                $file_contents .= fread($FILE, 8192);
                                            }
                                            fclose($FILE);

                                            // store file locally
                                            //
                                            global $attachment_dir, $username;
                                            $hashed_attachment_dir = getHashedDir($username, $attachment_dir);
                                            $localfilename = GenerateRandomString(32, '', 7);
                                            $full_localfilename = "$hashed_attachment_dir/$localfilename";
                                            while (file_exists($full_localfilename)) {
                                                $localfilename = GenerateRandomString(32, '', 7);
                                                $full_localfilename = "$hashed_attachment_dir/$localfilename";
                                            }
                                            $FILE = fopen("$hashed_attachment_dir/$localfilename", 'wb');
                                            fwrite($FILE, $file_contents);
                                            fclose($FILE);

                                            // get mime type and remove file
                                            //
                                            $mime_type = mime_content_type("$hashed_attachment_dir/$localfilename");
                                            unlink("$hashed_attachment_dir/$localfilename");
                                        }
                                        // debug: echo "$attvalue FILE TYPE IS $mime_type<HR>";
                                        if (substr(strtolower($mime_type), 0, 5) != 'image') {
                                            $attvalue = $sQuote . SM_PATH . 'images/blank.png'. $sQuote;
                                        }
                                    }
                                    --------------------------------- */
                                } else {
                                    $attvalue = $sQuote . SM_PATH . 'images/blank.png'. $sQuote;
                                }
                            }
                        } else {
                            $attvalue = $sQuote . $attvalue . $sQuote;
                        }
                        break;
                    case 'outbind':
                        /**
                         * "Hack" fix for Outlook using propriatary outbind:// protocol in img tags.
                         * One day MS might actually make it match something useful, for now, falling
                         * back to using cid2http, so we can grab the blank.png.
                         */
                        $attvalue = $sQuote . sq_cid2http($message, $id, $attvalue, $mailbox) . $sQuote;
                        break;
                    case 'cid':
                        /**
                            * Turn cid: urls into http-friendly ones.
                            */
                        $attvalue = $sQuote . sq_cid2http($message, $id, $attvalue, $mailbox) . $sQuote;
                        break;
                    default:
                        $attvalue = $sQuote . SM_PATH . 'images/blank.png' . $sQuote;
                        break;
                }
            } else {
                if (!(isset($aUrl['path']) && $aUrl['path'] == $secremoveimg)) {
                    // parse_url did not lead to satisfying result
                    $attvalue = $sQuote . SM_PATH . 'images/blank.png' . $sQuote;
                }
            }
        }
    }
}

/**
 * This function edits the style definition to make them friendly and
 * usable in SquirrelMail.
 *
 * @param  $message  the message object
 * @param  $id       the message id
 * @param  $content  a string with whatever is between <style> and </style>
 * @param  $mailbox  the message mailbox
 * @return           a string with edited content.
 */
function sq_fixstyle($body, $pos, $message, $id, $mailbox){
    // FIXME: Is the global "view_unsafe_images" really needed here?
    global $view_unsafe_images;
    $me = 'sq_fixstyle';

    // workaround for </style> in between comments
    $iCurrentPos = $pos;
    $content = '';
    $sToken = '';
    $bSucces = false;
    $bEndTag = false;
    for ($i=$pos,$iCount=strlen($body);$i<$iCount;++$i) {
        $char = $body[$i];
        switch ($char) {
            case '<':
                $sToken = $char;
                break;
            case '/':
                 if ($sToken == '<') {
                    $sToken .= $char;
                    $bEndTag = true;
                 } else {
                    $content .= $char;
                 }
                 break;
            case '>':
                 if ($bEndTag) {
                    $sToken .= $char;
                    if (preg_match('/\<\/\s*style\s*\>/i',$sToken,$aMatch)) {
                        $newpos = $i + 1;
                        $bSucces = true;
                        break 2;
                    } else {
                        $content .= $sToken;
                    }
                    $bEndTag = false;
                 } else {
                    $content .= $char;
                 }
                 break;
            case '!':
                if ($sToken == '<') {
                    // possible comment
                    if (isset($body[$i+2]) && substr($body,$i,3) == '!--') {
                        $i = strpos($body,'-->',$i+3);
                        if ($i === false) { // no end comment
                            $i = strlen($body);
                        }
                        $sToken = '';
                    }
                } else {
                    $content .= $char;
                }
                break;
            default:
                if ($bEndTag) {
                    $sToken .= $char;
                } else {
                    $content .= $char;
                }
                break;
        }
    }
    if ($bSucces == FALSE){
        return array(FALSE, strlen($body));
    }

    /**
     * First look for general BODY style declaration, which would be
     * like so:
     * body {background: blah-blah}
     * and change it to .bodyclass so we can just assign it to a <div>
     */
    // $content = preg_replace("|body(\s*\{.*?\})|si", ".bodyclass\\1", $content);
    // Nah, this is even better - try to preface all CSS selectors with
    // our <div> class ID "bodyclass" then correct generic "body" selectors
    // TODO: this works pretty good but breaks stuff like this:
    //       @media print { body { font-size: 10pt; } }
    //       but there isn't an easy way to make this regex skip @media
    //       definitions... though lots of the ones in the wild will be
    //       correctly handled because they tend to end with a parenthesis, like:
    //       @media screen and (max-width:480px) { ...
    $content = preg_replace('/([a-z0-9._-][a-z0-9 >+~|:._-]*\s*(?:,|{.*?}))/si', '.bodyclass $1', $content);
    $content = str_replace('.bodyclass body', '.bodyclass', $content);

    global $use_transparent_security_image;
    if ($use_transparent_security_image) $secremoveimg = '../images/spacer.png';
    else $secremoveimg = '../images/' . _("sec_remove_eng.png");

    // first check for 8bit sequences and disallowed control characters
    if (preg_match('/[\16-\37\200-\377]+/',$content)) {
        $content = '<!-- style block removed by html filter due to presence of 8bit characters -->';
        return array($content, $newpos);
    }

    // IE Sucks hard. We have a special function for it.
    sq_fixIE_idiocy($content);

    // remove @import line
    $content = preg_replace("/^\s*(@import.*)$/mi","\n<!-- @import rules forbidden -->\n",$content);

    /**
     * Fix url('blah') declarations.
     */
    // translate ur\l and variations into url (IE parses that)
    // TODO check if the sq_fixIE_idiocy function already handles this.
    $content = preg_replace("/(\\\\)?u(\\\\)?r(\\\\)?l(\\\\)?/i",'url', $content);
    preg_match_all("/url\s*\((.+)\)/si",$content,$aMatch);
    if (count($aMatch)) {
        $aValue = $aReplace = array();
        foreach($aMatch[1] as $sMatch) {
            // url value
            $urlvalue = $sMatch;
            sq_fix_url('style',$urlvalue, $message, $id, $mailbox,"'");
            $aValue[] = $sMatch;
            $aReplace[] = $urlvalue;
        }
        $content = str_replace($aValue,$aReplace,$content);
    }

    /**
     * Remove any backslashes, entities, and extraneous whitespace.
     */
    $contentTemp = $content;
    sq_defang($contentTemp);
    sq_unspace($contentTemp);

    /**
     * Fix stupid css declarations which lead to vulnerabilities
     * in IE.
     *
     * Also remove "position" attribute, as it can easily be set
     * to "fixed" or "absolute" with "left" and "top" attributes
     * of zero, taking over the whole content frame.  It can also
     * be set to relative and move itself anywhere it wants to,
     * displaying content in areas it shouldn't be allowed to touch.
     */
    $match   = Array('/\/\*.*\*\//', // removes /* blah blah */
                    '/expression/i',
                    '/behaviou*r/i',
                    '/binding/i',
                    '/include-source/i',
                    '/javascript/i',
                    '/script/i',
                    '/position/i');
    $replace = Array('','idiocy', 'idiocy', 'idiocy', 'idiocy', 'idiocy', 'idiocy', '');
    $contentNew = preg_replace($match, $replace, $contentTemp);
    if ($contentNew !== $contentTemp) {
        // insecure css declarations are used. From now on we don't care
        // anymore if the css is destroyed by sq_deent, sq_unspace or sq_unbackslash
        $content = $contentNew;
    }
    return array($content, $newpos);
}


/**
 * This function converts cid: url's into the ones that can be viewed in
 * the browser.
 *
 * @param  $message  the message object
 * @param  $id       the message id
 * @param  $cidurl   the cid: url.
 * @param  $mailbox  the message mailbox
 * @return           a string with a http-friendly url
 */
function sq_cid2http($message, $id, $cidurl, $mailbox){
    /**
     * Get rid of quotes.
     */
    $quotchar = substr($cidurl, 0, 1);
    if ($quotchar == '"' || $quotchar == "'"){
        $cidurl = str_replace($quotchar, "", $cidurl);
    } else {
        $quotchar = '';
    }
    $cidurl = substr(trim($cidurl), 4);

    $match_str = '/\{.*?\}\//';
    $str_rep = '';
    $cidurl = preg_replace($match_str, $str_rep, $cidurl);

    $linkurl = find_ent_id($cidurl, $message);
    /* in case of non-safe cid links $httpurl should be replaced by a sort of
       unsafe link image */
    $httpurl = '';

    /**
     * This is part of a fix for Outlook Express 6.x generating
     * cid URLs without creating content-id headers. These images are
     * not part of the multipart/related html mail. The html contains
     * <img src="cid:{some_id}/image_filename.ext"> references to
     * attached images with as goal to render them inline although
     * the attachment disposition property is not inline.
     */

    if (empty($linkurl)) {
        if (preg_match('/{.*}\//', $cidurl)) {
            $cidurl = preg_replace('/{.*}\//','', $cidurl);
            if (!empty($cidurl)) {
                $linkurl = find_ent_id($cidurl, $message);
            }
        }
    }

    if (!empty($linkurl)) {
        $httpurl = $quotchar . SM_PATH . 'src/download.php?absolute_dl=true&amp;' .
            "passed_id=$id&amp;mailbox=" . urlencode($mailbox) .
            '&amp;ent_id=' . $linkurl . $quotchar;
    } else {
        /**
         * If we couldn't generate a proper img url, drop in a blank image
         * instead of sending back empty, otherwise it causes unusual behaviour
         */
        $httpurl = $quotchar . SM_PATH . 'images/blank.png' . $quotchar;
    }

    return $httpurl;
}

/**
 * This function changes the <body> tag into a <div> tag since we
 * can't really have a body-within-body.
 *
 * @param  $attary   an array of attributes and values of <body>
 * @param  $mailbox  mailbox we're currently reading (for cid2http)
 * @param  $message  current message (for cid2http)
 * @param  $id       current message id (for cid2http)
 * @return           a modified array of attributes to be set for <div>
 */
function sq_body2div($attary, $mailbox, $message, $id){
    $me = 'sq_body2div';
    $divattary = Array('class' => "'bodyclass'");
    $bgcolor = '#ffffff';
    $text = '#000000';
    $styledef = '';
    if (is_array($attary) && sizeof($attary) > 0){
        foreach ($attary as $attname=>$attvalue){
            $quotchar = substr($attvalue, 0, 1);
            $attvalue = str_replace($quotchar, "", $attvalue);
            switch ($attname){
                case 'background':
                    $attvalue = sq_cid2http($message, $id, $attvalue, $mailbox);
                    $styledef .= "background-image: url('$attvalue'); ";
                    break;
                case 'bgcolor':
                    $styledef .= "background-color: $attvalue; ";
                    break;
                case 'text':
                    $styledef .= "color: $attvalue; ";
                    break;
            }
        }
        if (strlen($styledef) > 0){
            $divattary["style"] = "\"$styledef\"";
        }
    }
    return $divattary;
}

/**
 * This is the main function and the one you should actually be calling.
 * There are several variables you should be aware of an which need
 * special description.
 *
 * NOTE: If the caller wants to inspect a list of the tags completely
 *       removed, it should check the global array $tags_removed
 *       immediately after calling this function
 *
 * Since the description is quite lengthy, see it here:
 * http://linux.duke.edu/projects/mini/htmlfilter/
 *
 * @param $body                 the string with HTML you wish to filter
 * @param $tag_list             see description above
 * @param $rm_tags_with_content see description above
 * @param $self_closing_tags    see description above
 * @param $force_tag_closing    see description above
 * @param $rm_attnames          see description above
 * @param $bad_attvals          see description above
 * @param $add_attr_to_tag      see description above
 * @param $message              message object
 * @param $id                   message id
 * @param $recursively_called   boolean flag for recursive calls into this function (optional; default FALSE)
 * @return                      sanitized html safe to show on your pages.
 */
function sq_sanitize($body,
                     $tag_list,
                     $rm_tags_with_content,
                     $self_closing_tags,
                     $force_tag_closing,
                     $rm_attnames,
                     $bad_attvals,
                     $add_attr_to_tag,
                     $message,
                     $id,
                     $mailbox,
                     $recursively_called=FALSE
                     ){
    $me = 'sq_sanitize';
    global $tags_removed;
    $tags_removed = array();

    /**
     * See if tag_list is of tags to remove or tags to allow.
     * false  means remove these tags
     * true   means allow these tags
     */
    $orig_tag_list = $tag_list;
    $rm_tags = array_shift($tag_list);

    /**
     * Normalize rm_tags and rm_tags_with_content.
     */
    @array_walk($tag_list, 'sq_casenormalize');
    @array_walk($rm_tags_with_content, 'sq_casenormalize');
    @array_walk($self_closing_tags, 'sq_casenormalize');

    $curpos = 0;
    $open_tags = Array();
    $trusted = "\n<!-- begin sanitized html -->\n";
    $skip_content = false;
    /**
     * Take care of netscape's stupid javascript entities like
     * &{alert('boo')};
     */
    $body = preg_replace("/&(\{.*?\};)/si", "&amp;\\1", $body);

    while (($curtag = sq_getnxtag($body, $curpos)) != FALSE){
        list($tagname, $attary, $tagtype, $lt, $gt) = $curtag;

        /**
         * RCDATA and RAWTEXT tags are handled differently:
         * next instance of closing tag is used, whether or not
         * the HTML is well formed before that
         */
        global $rcdata_rawtext_tags;
        if (!$recursively_called
         && in_array($tagname, $rcdata_rawtext_tags)
         && $tagtype === 1){
            $closing_tag = false;
            $closing_tag_offset = $curpos;
            // seek out the closing tag for the current RCDATA/RAWTEXT tag
            while (1) {
                // first we need to move forward to next available closing tag
                // (intentionally leave off the closing > and let sq_getnxtag() validate a proper tag syntax)
                $next_tag = sq_findnxreg($body, $closing_tag_offset, "</\s*$tagname");
                if ($next_tag === false) {
                    $closing_tag = false;
                    break;
                }
                // but then we have to make sure it's a well-formed tag
                $closing_tag = sq_getnxtag($body, $next_tag[0]);
                if ($closing_tag === false)
                    break;
                else if ($closing_tag[0] !== false
                 // these should be redundant
                 && $closing_tag[0] === $tagname && $closing_tag[2] === 2) {
                    $tags_removed_temporary = $tags_removed;
                    $trusted .= sq_sanitize(substr($body, $curpos, $closing_tag[4] - $curpos + 1),
                                            $orig_tag_list, $rm_tags_with_content, $self_closing_tags,
                                            $force_tag_closing, $rm_attnames, $bad_attvals, $add_attr_to_tag,
                                            $message, $id, $mailbox, true);
                    // Also works (slower?):
                    // $tags_removed = array_merge($tags_removed_temporary, $tags_removed);
                    $tags_removed = $tags_removed_temporary + $tags_removed;
                    $curpos = $closing_tag[4] + 1;
                    continue 2;
                }
                $closing_tag_offset = $next_tag[0] + 1;
            }
            if ($closing_tag === false)
            { /* no-op... there was no closing tag for this RCDATA/RAWTEXT tag - we could probably set $curpos to the end of $body, but this HTML is malformed anyway and should just fall apart on its own */ }
        }

        $free_content = substr($body, $curpos, $lt-$curpos);
        /**
         * Take care of <style>
         */
        if ($tagname == "style" && $tagtype == 1){
            list($free_content, $curpos) =
                sq_fixstyle($body, $gt+1, $message, $id, $mailbox);
            if ($free_content != FALSE){
                if ( !empty ($attary) ) {
                    $attary = sq_fixatts($tagname,
                                         $attary,
                                         $rm_attnames,
                                         $bad_attvals,
                                         $add_attr_to_tag,
                                         $message,
                                         $id,
                                         $mailbox
                                         );
                }
                $trusted .= sq_tagprint($tagname, $attary, $tagtype);
                $trusted .= $free_content;
                $trusted .= sq_tagprint($tagname, false, 2);
            }
            continue;
        }
        if ($skip_content == false){
            $trusted .= $free_content;
        }
        if ($tagname != FALSE){
            if ($tagtype == 2){
                if ($skip_content == $tagname){
                    /**
                     * Got to the end of tag we needed to remove.
                     */
                    $tagname = false;
                    $skip_content = false;
                } else {
                    if ($skip_content == false){
                        if ($tagname == "body"){
                            $tagname = "div";
                        }
                        if (isset($open_tags[$tagname]) &&
                                $open_tags[$tagname] > 0){
                            $open_tags[$tagname]--;
                        } else {
                            $tagname = false;
                        }
                    }
                }
            } else {
                /**
                 * $rm_tags_with_content
                 */
                if ($skip_content == false){
                    /**
                     * See if this is a self-closing type and change
                     * tagtype appropriately.
                     */
                    if ($tagtype == 1
                            && in_array($tagname, $self_closing_tags)){
                        $tagtype = 3;
                    }
                    /**
                     * See if we should skip this tag and any content
                     * inside it.
                     */
                    if ($tagtype == 1 &&
                            in_array($tagname, $rm_tags_with_content)){
                        $skip_content = $tagname;
                    } else {
                        if (($rm_tags == false
                                    && in_array($tagname, $tag_list)) ||
                                ($rm_tags == true &&
                                 !in_array($tagname, $tag_list))){
                            $tagname = false;
                        } else {
                            /**
                             * Convert body into div.
                             */
                            if ($tagname == "body"){
                                $tagname = "div";
                                $attary = sq_body2div($attary, $mailbox,
                                        $message, $id);
                            }
                            if ($tagtype == 1){
                                if (isset($open_tags[$tagname])){
                                    $open_tags[$tagname]++;
                                } else {
                                    $open_tags[$tagname]=1;
                                }
                            }
                            /**
                             * This is where we run other checks.
                             */
                            if (is_array($attary) && sizeof($attary) > 0){
                                $attary = sq_fixatts($tagname,
                                                     $attary,
                                                     $rm_attnames,
                                                     $bad_attvals,
                                                     $add_attr_to_tag,
                                                     $message,
                                                     $id,
                                                     $mailbox
                                                     );
                            }
                        }
                    }
                }
            }
            if ($tagname != false && $skip_content == false){
                $trusted .= sq_tagprint($tagname, $attary, $tagtype);
            }
            else if (!empty($tagname))
                $tags_removed[$tagname] = TRUE;
        }
        $curpos = $gt+1;
    }
    $trusted .= substr($body, $curpos, strlen($body)-$curpos);
    if ($force_tag_closing == true){
        foreach ($open_tags as $tagname=>$opentimes){
            while ($opentimes > 0){
                $trusted .= '</' . $tagname . '>';
                $opentimes--;
            }
        }
        $trusted .= "\n";
    }
    $trusted .= "<!-- end sanitized html -->\n";
    return $trusted;
}

/**
 * This is a wrapper function to call html sanitizing routines.
 *
 * @param  $body  the body of the message
 * @param  $id    the id of the message
 * @param  boolean $take_mailto_links When TRUE, converts mailto: links
 *                                    into internal SM compose links
 *                                    (optional; default = TRUE)
 * @return        a string with html safe to display in the browser.
 */
function magicHTML($body, $id, $message, $mailbox = 'INBOX', $take_mailto_links =true) {

    require_once(SM_PATH . 'functions/url_parser.php');  // for $MailTo_PReg_Match

    global $attachment_common_show_images, $view_unsafe_images,
           $has_unsafe_images, $allow_svg_display, $rcdata_rawtext_tags,
           $remove_rcdata_rawtext_tags_and_content,
           $treat_svg_separate_from_unsafe_images;

    // If there's no "view_unsafe_images" variable in the URL, turn unsafe
    // images off by default.
    if( !sqgetGlobalVar('view_unsafe_images', $view_unsafe_images, SQ_GET) ) {
        $view_unsafe_images = false;
    }

    $rcdata_rawtext_tags = array(
        "noscript",
        "noframes",
        "noembed",
        "textarea",
        // also "title", "xmp", "script", "iframe", "plaintext" which we already remove below
    );

    /**
     * Don't display attached images in HTML mode.
     */
    $attachment_common_show_images = false;
    $tag_list = Array(
            false, // remove these tags
            "meta",
            "html",
            "head",
            "base",
            "link",
            "frame",
            "iframe",
            "plaintext",
            "marquee",
            );

    $rm_tags_with_content = Array(
            "script",
            "object",
            "applet",
            "embed",
            "title",
            "frameset",
            "xmp",
            "xml",
            );
    if ((!$treat_svg_separate_from_unsafe_images && !$view_unsafe_images)
     || ($treat_svg_separate_from_unsafe_images && !$allow_svg_display))
        $rm_tags_with_content[] = 'svg';
    /**
     * SquirrelMail will parse RCDATA and RAWTEXT tags and handle them as the special
     * case that they are, but if you prefer to remove them and their contents entirely
     * (in most cases, should be a safe thing with minimal impact), you can add the
     * following to config/config_local.php
     *    $remove_rcdata_rawtext_tags_and_content = TRUE; 
     */
    if ($remove_rcdata_rawtext_tags_and_content)
        $rm_tags_with_content = array_merge($rm_tags_with_content, $rcdata_rawtext_tags);

    $self_closing_tags =  Array(
            "img",
            "br",
            "hr",
            "input",
            "outbind",
            );

    $force_tag_closing = true;

    $rm_attnames = Array(
            "/.*/" =>
            Array(
                "/target/i",
                "/^on.*/i",
                "/^dynsrc/i",
                "/^data.*/i",
                "/^lowsrc.*/i",
                )
            );

    global $use_transparent_security_image;
    if ($use_transparent_security_image) $secremoveimg = '../images/spacer.png';
    else $secremoveimg = '../images/' . _("sec_remove_eng.png");

    $bad_attvals = Array(
            "/.*/" =>
            Array(
                "/^src|background/i" =>
                Array(
                    Array(
                        "/^([\'\"])\s*\S+script\s*:.*([\'\"])/si",
                        "/^([\'\"])\s*mocha\s*:*.*([\'\"])/si",
                        "/^([\'\"])\s*about\s*:.*([\'\"])/si"
                        ),
                    Array(
                        "\\1$secremoveimg\\2",
                        "\\1$secremoveimg\\2",
                        "\\1$secremoveimg\\2"
                        )
                    ),
                "/^href|action/i" =>
                Array(
                    Array(
                        "/^([\'\"])\s*\S+script\s*:.*([\'\"])/si",
                        "/^([\'\"])\s*mocha\s*:*.*([\'\"])/si",
                        "/^([\'\"])\s*about\s*:.*([\'\"])/si"
                        ),
                    Array(
                        "\\1#\\1",
                        "\\1#\\1",
                        "\\1#\\1"
                        )
                    ),
        "/^style/i" =>
            Array(
                Array(
                    "/\/\*.*\*\//",
                    "/expression/i",
                    "/binding/i",
                    "/behaviou*r/i",
                    "/include-source/i",

                    // position:relative can also be exploited
                    // to put content outside of email body area
                    // and position:fixed is similarly exploitable
                    // as position:absolute, so we'll remove it
                    // altogether....
                    //
                    // Does this screw up legitimate HTML messages?
                    // If so, the only fix I see is to allow position
                    // attributes (any values?  I think we still have
                    // to block static and fixed) only if $use_iframe
                    // is enabled (1.5.0+)
                    //
                    // was:   "/position\s*:\s*absolute/i",
                    //
                    "/position\s*:/i",

                    "/(\\\\)?u(\\\\)?r(\\\\)?l(\\\\)?/i",
                    "/url\s*\(\s*([\'\"])\s*\S+script\s*:.*([\'\"])\s*\)/si",
                    "/url\s*\(\s*([\'\"])\s*mocha\s*:.*([\'\"])\s*\)/si",
                    "/url\s*\(\s*([\'\"])\s*about\s*:.*([\'\"])\s*\)/si",
                    "/(.*)\s*:\s*url\s*\(\s*([\'\"]*)\s*\S+script\s*:.*([\'\"]*)\s*\)/si",
                    ),
                Array(
                    "",
                    "idiocy",
                    "idiocy",
                    "idiocy",
                    "idiocy",
                    "idiocy",
                    "url",
                    "url(\\1#\\1)",
                    "url(\\1#\\1)",
                    "url(\\1#\\1)",
                    "\\1:url(\\2#\\3)"
                    )
                )
            )
        );

    if (!$view_unsafe_images){
        /**
         * Remove any references to http/https if view_unsafe_images set
         * to false.
         */
        array_push($bad_attvals['/.*/']['/^src|background/i'][0],
                '/^([\'\"])\s*https*:.*([\'\"])/si');
        array_push($bad_attvals['/.*/']['/^src|background/i'][1],
                "\\1$secremoveimg\\1");
        array_push($bad_attvals['/.*/']['/^style/i'][0],
                '/url\([\'\"]?https?:[^\)]*[\'\"]?\)/si');
        array_push($bad_attvals['/.*/']['/^style/i'][1],
                "url(\\1$secremoveimg\\1)");
    }

    $add_attr_to_tag = Array(
            "/^a$/i" =>
            Array('target'=>'"_blank"',
                'title'=>'"'._("This external link will open in a new window").'"'
                )
            );
    $trusted = sq_sanitize($body,
                           $tag_list,
                           $rm_tags_with_content,
                           $self_closing_tags,
                           $force_tag_closing,
                           $rm_attnames,
                           $bad_attvals,
                           $add_attr_to_tag,
                           $message,
                           $id,
                           $mailbox
                           );
    if (!$treat_svg_separate_from_unsafe_images && !$view_unsafe_images){
        global $tags_removed;
        if (array_key_exists('svg', $tags_removed)){
            $has_unsafe_images = true;
       }
    }
    if (strpos($trusted,$secremoveimg)){
        $has_unsafe_images = true;
    }

    // we want to parse mailto's in HTML output, change to SM compose links
    // this is a modified version of code from url_parser.php... but Marc is
    // right: we need a better filtering implementation; adding this randomly
    // here is not a great solution
    //
    if ($take_mailto_links) {
        // parseUrl($trusted);   // this even parses URLs inside of tags... too aggressive
        global $MailTo_PReg_Match;
        // some mailers (Microsoft, surprise surprise) produce mailto strings without being
        // inside an anchor (link) tag, so we have to make sure the regex looks for the
        // quote before mailto, and we'll also try to convert the non-links back into links
        $MailTo_PReg_Match = '/([\'"])?mailto:' . substr($MailTo_PReg_Match, 1) ;
        if ((preg_match_all($MailTo_PReg_Match, $trusted, $regs)) && ($regs[0][0] != '')) {
            foreach ($regs[0] as $i => $mailto_before) {
                $mailto_params = $regs[11][$i];

                // get rid of any leading quote we may have captured but don't care about
                //
                $mailto_before = ltrim($mailto_before, '"\'');

                // get rid of any tailing quote since we have to add send_to to the end
                //
                $mailto_before = rtrim($mailto_before, '"\'');
                $mailto_params = rtrim($mailto_params, '"\'');

                if ($regs[2][$i]) {    //if there is an email addr before '?', we need to merge it with the params
                    $to = 'to=' . $regs[2][$i];
                    if (strpos($mailto_params, 'to=') > -1)    //already a 'to='
                        $mailto_params = str_replace('to=', $to . '%2C%20', $mailto_params);
                    else {
                        if ($mailto_params)    //already some params, append to them
                            $mailto_params .= '&amp;' . $to;
                        else
                            $mailto_params .= '?' . $to;
                    }
                }

                $url_str = preg_replace(array('/to=/i', '/(?<!b)cc=/i', '/bcc=/i'), array('send_to=', 'send_to_cc=', 'send_to_bcc='), $mailto_params);

                // we'll already have target=_blank, no need to allow comp_in_new
                // here (which would be a lot more work anyway)
                //
                global $compose_new_win;
                $temp_comp_in_new = $compose_new_win;
                $compose_new_win = 0;
                $comp_uri = makeComposeLink('src/compose.php' . $url_str, $mailto_before);
                $compose_new_win = $temp_comp_in_new;

                // remove <a href=" and anything after the next quote (we only
                // need the uri, not the link HTML) in compose uri
                //
                // but only do this if the original mailto was in a real anchor tag
                //
                if (!empty($regs[1][$i])) {
                    $comp_uri = substr($comp_uri, 9);
                    $comp_uri = substr($comp_uri, 0, strpos($comp_uri, '"', 1));
                }
                $trusted = str_replace($mailto_before, $comp_uri, $trusted);
            }
        }
    }

    return $trusted;
}

/**
 * function SendDownloadHeaders - send file to the browser
 *
 * Original Source: SM core src/download.php
 * moved here to make it available to other code, and separate
 * front end from back end functionality.
 *
 * @param string $type0 first half of mime type
 * @param string $type1 second half of mime type
 * @param string $filename filename to tell the browser for downloaded file
 * @param boolean $force whether to force the download dialog to pop
 * @param optional integer $filesize send the Content-Header and length to the browser
 * @return void
 */
function SendDownloadHeaders($type0, $type1, $filename, $force, $filesize=0) {
    global $languages, $squirrelmail_language;
    $isIE = $isIE6plus = false;

    sqgetGlobalVar('HTTP_USER_AGENT', $HTTP_USER_AGENT, SQ_SERVER);

    if (strstr($HTTP_USER_AGENT, 'compatible; MSIE ') !== false &&
            strstr($HTTP_USER_AGENT, 'Opera') === false) {
        $isIE = true;
    }

    if (preg_match('/compatible; MSIE ([0-9]+)/', $HTTP_USER_AGENT, $match) &&
        ((int)$match[1]) >= 6 && strstr($HTTP_USER_AGENT, 'Opera') === false) {
        $isIE6plus = true;
    }

    if (isset($languages[$squirrelmail_language]['XTRA_CODE']) &&
            function_exists($languages[$squirrelmail_language]['XTRA_CODE'])) {
        $filename =
            $languages[$squirrelmail_language]['XTRA_CODE']('downloadfilename', $filename, $HTTP_USER_AGENT);
    } else {
        $filename = preg_replace('/[\\\\\/:*?"<>|;]/', '_', str_replace('&#32;', ' ', $filename));
    }

    // A Pox on Microsoft and it's Internet Explorer!
    //
    // IE has lots of bugs with file downloads.
    // It also has problems with SSL.  Both of these cause problems
    // for us in this function.
    //
    // See this article on Cache Control headers and SSL
    // http://support.microsoft.com/default.aspx?scid=kb;en-us;323308
    //
    // The best thing you can do for IE is to upgrade to the latest
    // version
    //set all the Cache Control Headers for IE
    if ($isIE) {
        $filename=rawurlencode($filename);
        header ("Pragma: public");
        header ("Cache-Control: no-store, max-age=0, no-cache, must-revalidate"); // HTTP/1.1
        // does nothing - see: https://blogs.msdn.microsoft.com/ieinternals/2009/07/20/internet-explorers-cache-control-extensions/
        // header ("Cache-Control: post-check=0, pre-check=0", false);
        header ("Cache-Control: private");

        //set the inline header for IE, we'll add the attachment header later if we need it
        header ("Content-Disposition: inline; filename=$filename");
    }

    if (!$force) {
        // Try to show in browser window
        header ("Content-Disposition: inline; filename=\"$filename\"");
        header ("Content-Type: $type0/$type1; name=\"$filename\"");
    } else {
        // Try to pop up the "save as" box

        // IE makes this hard.  It pops up 2 save boxes, or none.
        // http://support.microsoft.com/support/kb/articles/Q238/5/88.ASP
        // http://support.microsoft.com/default.aspx?scid=kb;EN-US;260519
        // But, according to Microsoft, it is "RFC compliant but doesn't
        // take into account some deviations that allowed within the
        // specification."  Doesn't that mean RFC non-compliant?
        // http://support.microsoft.com/support/kb/articles/Q258/4/52.ASP

        // all browsers need the application/octet-stream header for this
        header ("Content-Type: application/octet-stream; name=\"$filename\"");

        // http://support.microsoft.com/support/kb/articles/Q182/3/15.asp
        // Do not have quotes around filename, but that applied to
        // "attachment"... does it apply to inline too?
        header ("Content-Disposition: attachment; filename=\"$filename\"");

        if ($isIE && !$isIE6plus) {
            // This combination seems to work mostly.  IE 5.5 SP 1 has
            // known issues (see the Microsoft Knowledge Base)

            // This works for most types, but doesn't work with Word files
            header ("Content-Type: application/download; name=\"$filename\"");
            // This is to prevent IE for MIME sniffing and auto open a file in IE
            header ("Content-Type: application/force-download; name=\"$filename\"");
            // These are spares, just in case.  :-)
            //header("Content-Type: $type0/$type1; name=\"$filename\"");
            //header("Content-Type: application/x-msdownload; name=\"$filename\"");
            //header("Content-Type: application/octet-stream; name=\"$filename\"");
        } else if ($isIE) {
             // This is to prevent IE for MIME sniffing and auto open a file in IE
             header ("Content-Type: application/force-download; name=\"$filename\"");
        } else {
            // another application/octet-stream forces download for Netscape
            header ("Content-Type: application/octet-stream; name=\"$filename\"");
        }
    }

    //send the content-length header if the calling function provides it
    if ($filesize > 0) {
        header("Content-Length: $filesize");
    }

}  // end fn SendDownloadHeaders
