[squirrelmail.git] / functions / mime.php

<?php

/**
 * mime.php
 *
 * Copyright (c) 1999-2002 The SquirrelMail Project Team
 * Licensed under the GNU GPL. For full terms see the file COPYING.
 *
 * This contains the functions necessary to detect and decode MIME
 * messages.
 *
 * $Id$
 */

require_once('../functions/imap.php');
require_once('../functions/attachment_common.php');

/** Setting up the objects that have the structure for the message **/
class msg_header {
    /** msg_header contains generic variables for values that **/
    /** could be in a header.                                 **/

    var $type0 = '', $type1 = '', $boundary = '', $charset = '';
    var $encoding = '', $size = 0, $to = array(), $from = '', $date = '';
    var $cc = array(), $bcc = array(), $reply_to = '', $subject = '';
    var $id = 0, $mailbox = '', $description = '', $filename = '';
    var $entity_id = 0, $message_id = 0, $name = '';
    // var $priority = "";
}

class message {
    /** message is the object that contains messages.  It is a recursive
      object in that through the $entities variable, it can contain
      more objects of type message.  See documentation in mime.txt for
      a better description of how this works.
    **/
    var $header = '';
    var $entities = array();
    
    function addEntity ($msg) {
        $this->entities[] = $msg;
    }
}

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

/* 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 ($imap_stream, $header) {

    sqimap_messages_flag ($imap_stream, $header->id, $header->id, 'Seen');
    $ssid = sqimap_session_id();
    $lsid = strlen( $ssid );
    $id = $header->id;
    fputs ($imap_stream, "$ssid FETCH $id BODYSTRUCTURE\r\n");
    //
    // This should use sqimap_read_data instead of reading it itself
    //
    $read = fgets ($imap_stream, 10000);
    $bodystructure = '';
    while ( substr($read, 0, $lsid) <> $ssid &&
         !feof( $imap_stream ) ) {
        $bodystructure .= $read;
        $read = fgets ($imap_stream, 10000);
    }
    $read = $bodystructure;
    
    // isolate the body structure and remove beginning and end parenthesis
    $read = trim(substr ($read, strpos(strtolower($read), 'bodystructure') + 13));
    $read = trim(substr ($read, 0, -1));
    $end = mime_match_parenthesis(0, $read);
    while ($end == strlen($read)-1) {
        $read = trim(substr ($read, 0, -1));
        $read = trim(substr ($read, 1));
        $end = mime_match_parenthesis(0, $read);
    }
    
    $msg = mime_parse_structure ($read, 0);
    $msg->header = $header;
    
    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
 * $message.
 * First, it checks to see if it is a multipart message.  If it is, then it
 * handles that as it sees is necessary.  If it is just a regular entity,
 * then it parses it and adds the necessary header information (by calling out
 * to mime_get_elements()
 */
function mime_parse_structure ($structure, $ent_id) {

  $msg = new message();
  if ($structure{0} == '(') {
     $ent_id = mime_new_element_level($ent_id);
     $start = $end = -1;
     do {
        $start = $end+1;
        $end = mime_match_parenthesis ($start, $structure);

        $element = substr($structure, $start+1, ($end - $start)-1);
        $ent_id = mime_increment_id ($ent_id);
        $newmsg = mime_parse_structure ($element, $ent_id);
        $msg->addEntity ($newmsg);
     } while ($structure{$end+1} == '(');
  } else {
     // parse the elements
     $msg = mime_get_element ($structure, $msg, $ent_id);
  }
  return $msg;
}

/* Increments the element ID.  An element id can look like any of
 * the following:  1, 1.2, 4.3.2.4.1, etc.  This function increments
 * the last number of the element id, changing 1.2 to 1.3.
 */
function mime_increment_id ($id) {

    if (strpos($id, ".")) {
        $first = substr($id, 0, strrpos($id, "."));
        $last = substr($id, strrpos($id, ".")+1);
        $last++;
        $new = $first . "." .$last;
    } else {
        $new = $id + 1;
    }
    
    return $new;
}

/*
 * See comment for mime_increment_id().
 * This adds another level on to the entity_id changing 1.3 to 1.3.0
 * NOTE:  1.3.0 is not a valid element ID.  It MUST be incremented
 *        before it can be used.  I left it this way so as not to have
 *        to make a special case if it is the first entity_id.  It
 *        always increments it, and that works fine.
 */
function mime_new_element_level ($id) {

  if (!$id) {
      $id = 0;
  } else {
      $id = $id . '.0';
  }

  return( $id );
}

function mime_get_element (&$structure, $msg, $ent_id) {

  $elem_num = 1;
  $msg->header = new msg_header();
  $msg->header->entity_id = $ent_id;
  $properties = array();

  while (strlen($structure) > 0) {
     $structure = trim($structure);
     $char = $structure{0};

     if (strtolower(substr($structure, 0, 3)) == 'nil') {
        $text = '';
        $structure = substr($structure, 3);
     } else if ($char == '"') {
        // loop through until we find the matching quote, and return that as a string
        $pos = 1;
        $text = '';
        while ( ($char = $structure{$pos} ) <> '"' && $pos < strlen($structure)) {
           $text .= $char;
           $pos++;
        }
        $structure = substr($structure, strlen($text) + 2);
     } else if ($char == '(') {
        // comment me
        $end = mime_match_parenthesis (0, $structure);
        $sub = substr($structure, 1, $end-1);
        $properties = mime_get_props($properties, $sub);
        $structure = substr($structure, strlen($sub) + 2);
     } else {
        // loop through until we find a space or an end parenthesis
        $pos = 0;
        $char = $structure{$pos};
        $text = '';
        while ($char != ' ' && $char != ')' && $pos < strlen($structure)) {
           $text .= $char;
           $pos++;
           $char = $structure{$pos};
        }
        $structure = substr($structure, strlen($text));
     }

     // This is where all the text parts get put into the header
     switch ($elem_num) {
        case 1:
           $msg->header->type0 = strtolower($text);
           break;
        case 2:
           $msg->header->type1 = strtolower($text);
           break;
        case 4: // Id
           // Invisimail enclose images with <>
           $msg->header->id = str_replace( '<', '', str_replace( '>', '', $text ) );
           break;
        case 5:
           $msg->header->description = $text;
           break;
        case 6:
           $msg->header->encoding = strtolower($text);
           break;
        case 7:
           $msg->header->size = $text;
           break;
        default:
           if ($msg->header->type0 == 'text' && $elem_num == 8) {
              // This is a plain text message, so lets get the number of lines
              // that it contains.
              $msg->header->num_lines = $text;

           } else if ($msg->header->type0 == 'message' && $msg->header->type1 == 'rfc822' && $elem_num == 8) {
              // This is an encapsulated message, so lets start all over again and
              // parse this message adding it on to the existing one.
              $structure = trim($structure);
              if ( $structure{0} == '(' ) {
                 $e = mime_match_parenthesis (0, $structure);
                 $structure = substr($structure, 0, $e);
                 $structure = substr($structure, 1);
                 $m = mime_parse_structure($structure, $msg->header->entity_id);

                 // the following conditional is there to correct a bug that wasn't
                 // incrementing the entity IDs correctly because of the special case
                 // that message/rfc822 is.  This fixes it fine.
                 if (substr($structure, 1, 1) != '(')
                    $m->header->entity_id = mime_increment_id(mime_new_element_level($ent_id));

                 // Now we'll go through and reformat the results.
                 if ($m->entities) {
                    for ($i=0; $i < count($m->entities); $i++) {
                       $msg->addEntity($m->entities[$i]);
                    }
                 } else {
                    $msg->addEntity($m);
                 }
                 $structure = "";
              }
           }
           break;
     }
     $elem_num++;
     $text = "";
  }
  // loop through the additional properties and put those in the various headers
  if ($msg->header->type0 != 'message') {
     for ($i=0; $i < count($properties); $i++) {
        $msg->header->{$properties[$i]['name']} = $properties[$i]['value'];
     }
  }

  return $msg;
}

/*
 * I did most of the MIME stuff yesterday (June 20, 2000), but I couldn't
 * figure out how to do this part, so I decided to go to bed.  I woke up
 * in the morning and had a flash of insight.  I went to the white-board
 * and scribbled it out, then spent a bit programming it, and this is the
 * result.  Nothing complicated, but I think my brain was fried yesterday.
 * Funny how that happens some times.
 *
 * This gets properties in a nested parenthesisized list.  For example,
 * this would get passed something like:  ("attachment" ("filename" "luke.tar.gz"))
 * This returns an array called $props with all paired up properties.
 * It ignores the "attachment" for now, maybe that should change later
 * down the road.  In this case, what is returned is:
 *    $props[0]["name"] = "filename";
 *    $props[0]["value"] = "luke.tar.gz";
 */
function mime_get_props ($props, $structure) {

  while (strlen($structure) > 0) {
     $structure = trim($structure);
     $char = $structure{0};

     if ($char == '"') {
        $pos = 1;
        $tmp = '';
        while ( ( $char = $structure{$pos} ) != '"' &&
                $pos < strlen($structure)) {
           $tmp .= $char;
           $pos++;
        }
        $structure = trim(substr($structure, strlen($tmp) + 2));
        $char = $structure{0};

        if ($char == '"') {
           $pos = 1;
           $value = '';
           while ( ( $char = $structure{$pos} ) != '"' &&
                   $pos < strlen($structure) ) {
              $value .= $char;
              $pos++;
           }
           $structure = trim(substr($structure, strlen($tmp) + 2));

           $k = count($props);
           $props[$k]['name'] = strtolower($tmp);
           $props[$k]['value'] = $value;
        } else if ($char == '(') {
           $end = mime_match_parenthesis (0, $structure);
           $sub = substr($structure, 1, $end-1);
       if (! isset($props))
           $props = array();
           $props = mime_get_props($props, $sub);
           $structure = substr($structure, strlen($sub) + 2);
        }
        return $props;
     } else if ($char == '(') {
        $end = mime_match_parenthesis (0, $structure);
        $sub = substr($structure, 1, $end-1);
        $props = mime_get_props($props, $sub);
        $structure = substr($structure, strlen($sub) + 2);
        return $props;
     } else {
        return $props;
     }
  }
}

/*
 *  Matches parenthesis.  It will return the position of the matching
 *  parenthesis in $structure.  For instance, if $structure was:
 *     ("text" "plain" ("val1name", "1") nil ... )
 *     x                                         x
 *  then this would return 42 to match up those two.
 */
function mime_match_parenthesis ($pos, $structure) {

    $j = strlen( $structure );
    
    // ignore all extra characters
    // If inside of a string, skip string -- Boundary IDs and other
    // things can have ) in them.
    if ( $structure{$pos} != '(' ) {
        return( $j );
    }
    
    while ( $pos < $j ) {
        $pos++;
        if ($structure{$pos} == ')') {
            return $pos;
        } elseif ($structure{$pos} == '"') {
            $pos++;
            while ( $structure{$pos} != '"' &&
                    $pos < $j ) {
               if (substr($structure, $pos, 2) == '\\"') {
                  $pos++;
               } elseif (substr($structure, $pos, 2) == '\\\\') {
                  $pos++;
               }
               $pos++;
            }
        } elseif ( $structure{$pos} == '(' ) {
            $pos = mime_match_parenthesis ($pos, $structure);
        }
    }
    echo _("Error decoding mime structure.  Report this as a bug!") . '<br>';
    return( $pos );
}

function mime_fetch_body ($imap_stream, $id, $ent_id ) {
    // do a bit of error correction.  If we couldn't find the entity id, just guess
    // that it is the first one.  That is usually the case anyway.
    if (!$ent_id)
        $ent_id = 1;
    $data = sqimap_run_command ($imap_stream, "FETCH $id BODY[$ent_id]", true, $response, $message);
    $topline = array_shift($data);
    while (! ereg('\\* [0-9]+ FETCH ', $topline) && $data)
        $topline = array_shift($data);
    $wholemessage = implode('', $data);
    if (ereg('\\{([^\\}]*)\\}', $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);
            $base = '';
            $k = 10;
            foreach( $data as $d ) {
                if ( substr( $d, 0, 13 ) == 'Content-Base:' ) {
                    $j = strlen( $d );
                    $i = 13;
                    $base = '';
                    while ( $i < $j &&
                           ( !isNoSep( $d{$i} ) || $d{$i} == '"' )  )
                        $i++;
                    while ( $i < $j ) {
                        if ( isNoSep( $d{$i} ) )
                            $base .= $d{$i};
                        $i++;
                    }
                    $k = 0;
                } elseif ( $k == 1 && !isnosep( $d{0} ) ) {
                    $base .= substr( $d, 1 );
                }
                $k++;
            }
            if ( $base <> '' )
                
                $ret = "<base href=\"$base\">" . $ret;
        }
    } else if (ereg('"([^"]*)"', $topline, $regs)) {
        $ret = $regs[1];
    } else {
        global $where, $what, $mailbox, $passed_id, $startMessage;
        $par = "mailbox=".urlencode($mailbox)."&passed_id=$passed_id";
        if (isset($where) && isset($what)) {
            $par .= "&where=".urlencode($where)."&what=".urlencode($what);
        } else {
            $par .= "&startMessage=$startMessage&show_more=0";
        }
        $par .= '&response='.urlencode($response).'&message='.urlencode($message).
                '&topline='.urlencode($topline);

        echo   '<b><font color=$color[2]>' .
               _("Body retrieval error. The reason for this is most probably that the message is malformed. Please help us making future versions better by submitting this message to the developers knowledgebase!") .
               "<A HREF=\"../src/retrievalerror.php?$par\">Submit message</A><BR>" .
               '<tt>' . _("Response:") . "$response<BR>" .
               _("Message:") . " $message<BR>" .
               _("FETCH line:") . " $topline<BR></tt></font></b>";

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

        $ret = "---------------\n$wholemessage";

    }
    return( $ret );
}

function mime_print_body_lines ($imap_stream, $id, $ent_id, $encoding) {
    // do a bit of error correction.  If we couldn't find the entity id, just guess
    // that it is the first one.  That is usually the case anyway.
    if (!$ent_id) {
        $ent_id = 1;
    }
    $sid = sqimap_session_id();
    // Don't kill the connection if the browser is over a dialup
    // and it would take over 30 seconds to download it.
    set_time_limit(0);
    
    fputs ($imap_stream, "$sid FETCH $id BODY[$ent_id]\r\n");
    $cnt = 0;
    $continue = true;
    $read = fgets ($imap_stream,4096);
    // This could be bad -- if the section has sqimap_session_id() . ' OK'
    // or similar, it will kill the download.
    while (!ereg("^".$sid." (OK|BAD|NO)(.*)$", $read, $regs)) {
      if (trim($read) == ')==') {
          $read1 = $read;
          $read = fgets ($imap_stream,4096);
          if (ereg("^".$sid." (OK|BAD|NO)(.*)$", $read, $regs)) {
              return;
          } else {
              echo decodeBody($read1, $encoding) .
                   decodeBody($read, $encoding);
          }
      } else if ($cnt) {
          echo decodeBody($read, $encoding);
      }
      $read = fgets ($imap_stream,4096);
      $cnt++;
    }
}

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


/* This is the first function called.  It decides if this is a multipart
   message or if it should be handled as a single entity
 */
function decodeMime ($imap_stream, &$header) {
    global $username, $key, $imapServerAddress, $imapPort;
    return mime_structure ($imap_stream, $header);
}

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

/* returns a $message object for a particular entity id */
function getEntity ($message, $ent_id) {
    if ($message) {
        if ($message->header->entity_id == $ent_id && strlen($ent_id) == strlen($message->header->entity_id)) {
            return $message;
        } else {
            for ($i = 0; isset($message->entities[$i]); $i++) {
                $msg = getEntity ($message->entities[$i], $ent_id);
                if ($msg) {
                    return $msg;
                }
            }
        }
    }
}

/*
 * figures out what entity to display and returns the $message object
 * for that entity.
 */
function findDisplayEntity ($message, $textOnly = 1)   {
    global $show_html_default;
    
    $entity = 0;
    
    if ($message) {
        if ( $message->header->type0 == 'multipart' &&
             ( $message->header->type1 == 'alternative' ||
               $message->header->type1 == 'related' ) &&
             $show_html_default && ! $textOnly ) {
            $entity = findDisplayEntityHTML($message);
        }
    
        // Show text/plain or text/html -- the first one we find.
        if ( $entity == 0 &&
             $message->header->type0 == 'text' &&
             ( $message->header->type1 == 'plain' ||
               $message->header->type1 == 'html' ) &&
             isset($message->header->entity_id) ) {
            $entity = $message->header->entity_id;
        }
    
        $i = 0;
        while ($entity == 0 && isset($message->entities[$i]) ) {
            $entity = findDisplayEntity($message->entities[$i], $textOnly);
            $i++;
        }
    }
    
    return( $entity );
}

/* Shows the HTML version */
function findDisplayEntityHTML ($message) {

    if ( $message->header->type0 == 'text' &&
         $message->header->type1 == 'html' &&
         isset($message->header->entity_id)) {
        return $message->header->entity_id;
    }
    for ($i = 0; isset($message->entities[$i]); $i ++) {
        $entity = findDisplayEntityHTML($message->entities[$i]);
        if ($entity != 0) {
            return $entity;
        }
    }
    
    return 0;
}

/* 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) {
    // 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, $username, $key, $imapServerAddress, $imapPort,
           $show_html_default;
    
    $id = $message->header->id;
    $urlmailbox = urlencode($message->header->mailbox);
    
    // Get the right entity and redefine message to be this entity
    // Pass the 0 to mean that we want the 'best' viewable one
    $ent_num = findDisplayEntity ($message, 0);
    $body_message = getEntity($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);
        $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') {
            if ( $show_html_default <> 1 ) {
                $body = strip_tags( $body );
                translateText($body, $wrap_at, $body_message->header->charset);
            } else {
                $body = MagicHTML( $body, $id );
            }
        } else {
            translateText($body, $wrap_at, $body_message->header->charset);
        }
        
        $body .= "<SMALL><CENTER><A HREF=\"../src/download.php?absolute_dl=true&passed_id=$id&passed_ent_id=$ent_num&mailbox=$urlmailbox&showHeaders=1\">". _("Download this as a file") ."</A></CENTER><BR></SMALL>";
        
        /** Display the ATTACHMENTS: message if there's more than one part **/
        $body .= "</TD></TR></TABLE>";
        if (isset($message->entities[0])) {
            $body .= formatAttachments ($message, $ent_num, $message->header->mailbox, $id);
        }
        $body .= "</TD></TR></TABLE>";
    } else {
        $body = formatAttachments ($message, -1, $message->header->mailbox, $id);
    }
    return ($body);
}

/*
 * A recursive function that returns a list of attachments with links
 * to where to download these attachments
 */
function formatAttachments ($message, $ent_id, $mailbox, $id) {
  global $where, $what;
  global $startMessage, $color;
  static $ShownHTML = 0;

  $body = "";
  if ($ShownHTML == 0) {
        $ShownHTML = 1;

        $body .= "<TABLE WIDTH=\"100%\" CELLSPACING=0 CELLPADDING=2 BORDER=0 BGCOLOR=\"$color[0]\"><TR>\n" .
                 "<TH ALIGN=\"left\" BGCOLOR=\"$color[9]\"><B>\n" .
                 _("Attachments") . ':' .
                 "</B></TH></TR><TR><TD>\n" .
                 "<TABLE CELLSPACING=0 CELLPADDING=1 BORDER=0>\n" .
                 formatAttachments ($message, $ent_id, $mailbox, $id) .
                 "</TABLE></TD></TR></TABLE>";

        return( $body );
  }

  if ($message) {
     if (!$message->entities) {
        $type0 = strtolower($message->header->type0);
        $type1 = strtolower($message->header->type1);
        $name = decodeHeader($message->header->name);

        if ($message->header->entity_id != $ent_id) {
           $filename = decodeHeader($message->header->filename);
           if (trim($filename) == '') {
              if (trim($name) == '') {
                 if ( trim( $message->header->id ) == '' )
                    $display_filename = 'untitled-[' . $message->header->entity_id . ']' ;
                 else
                    $display_filename = 'cid: ' . $message->header->id;
                 // $display_filename = 'untitled-[' . $message->header->entity_id . ']' ;
              } else {
                 $display_filename = $name;
                 $filename = $name;
              }
           } else {
              $display_filename = $filename;
           }

           $urlMailbox = urlencode($mailbox);
           $ent = urlencode($message->header->entity_id);

           $DefaultLink =
              "../src/download.php?startMessage=$startMessage&passed_id=$id&mailbox=$urlMailbox&passed_ent_id=$ent";
           if ($where && $what)
              $DefaultLink .= '&where=' . urlencode($where) . '&what=' . urlencode($what);
           $Links['download link']['text'] = _("download");
           $Links['download link']['href'] =
               "../src/download.php?absolute_dl=true&passed_id=$id&mailbox=$urlMailbox&passed_ent_id=$ent";
           $ImageURL = '';

           $HookResults = do_hook("attachment $type0/$type1", $Links,
               $startMessage, $id, $urlMailbox, $ent, $DefaultLink,
               $display_filename, $where, $what);

           $Links = $HookResults[1];
           $DefaultLink = $HookResults[6];

           $body .= '<TR><TD>&nbsp;&nbsp;</TD><TD>' .
                    "<A HREF=\"$DefaultLink\">$display_filename</A>&nbsp;</TD>" .
                    '<TD><SMALL><b>' . show_readable_size($message->header->size) .
                    '</b>&nbsp;&nbsp;</small></TD>' .
                    "<TD><SMALL>[ $type0/$type1 ]&nbsp;</SMALL></TD>" .
                    '<TD><SMALL>';
           if ($message->header->description)
              $body .= '<b>' . htmlspecialchars($message->header->description) . '</b>';
           $body .= '</SMALL></TD><TD><SMALL>&nbsp;';


           $SkipSpaces = 1;
           foreach ($Links as $Val) {
              if ($SkipSpaces) {
                 $SkipSpaces = 0;
              } else {
                 $body .= '&nbsp;&nbsp;|&nbsp;&nbsp;';
              }
              $body .= '<a href="' . $Val['href'] . '">' .  $Val['text'] . '</a>';
           }

           unset($Links);

           $body .= "</SMALL></TD></TR>\n";
        }
     } else {
        for ($i = 0; $i < count($message->entities); $i++) {
           $body .= formatAttachments ($message->entities[$i], $ent_id, $mailbox, $id);
        }
     }
     return( $body );
  }
}


/** this function decodes the body depending on the encoding type. **/
function decodeBody($body, $encoding) {
  $body = str_replace("\r\n", "\n", $body);
  $encoding = strtolower($encoding);

  global $show_html_default;

  if ($encoding == 'quoted-printable') {
     $body = quoted_printable_decode($body);


     while (ereg("=\n", $body))
        $body = ereg_replace ("=\n", "", $body);

  } else if ($encoding == 'base64') {
     $body = base64_decode($body);
  }

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

/*
 * This functions decode strings that is encoded according to
 * RFC1522 (MIME Part Two: Message Header Extensions for Non-ASCII Text).
 */
function decodeHeader ($string, $utfencode=true) {
  if (eregi('=\\?([^?]+)\\?(q|b)\\?([^?]+)\\?=',
            $string, $res)) {
     if (ucfirst($res[2]) == "B") {
        $replace = base64_decode($res[3]);
     } else {
        $replace = ereg_replace("_", " ", $res[3]);
    // Convert lowercase Quoted Printable to uppercase for
    // quoted_printable_decode to understand it.
    while (ereg("(=(([0-9][abcdef])|([abcdef][0-9])|([abcdef][abcdef])))", $replace, $res)) {
       $replace = str_replace($res[1], strtoupper($res[1]), $replace);
    }
        $replace = quoted_printable_decode($replace);
     }
     /* Only encode into entities by default. Some places
        don't need the encoding, like the compose form. */
     if ($utfencode){
         $replace = charset_decode ($res[1], $replace);
     }

     // Remove the name of the character set.
     $string = eregi_replace ('=\\?([^?]+)\\?(q|b)\\?([^?]+)\\?=',
         $replace, $string);

     // In case there should be more encoding in the string: recurse
     return (decodeHeader($string));
  } else
     return ($string);
}

/*
 * 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;
    
    // Encode only if the string contains 8-bit characters or =?
    $j = strlen( $string  );
    $l = strstr($string, '=?');         // Must be encoded ?
    $ret = '';
    for( $i=0; $i < $j; ++$i) {
        switch( $string{$i} ) {
           case '=':
          $ret .= '=3D';
          break;
        case '?':
          $ret .= '=3F';
          break;
        case '_':
          $ret .= '=5F';
          break;
        case ' ':
          $ret .= '_';
          break;
        default:
          $k = ord( $string{$i} );
          if ( $k > 126 ) {
             $ret .= sprintf("=%02X", $k);
             $l = TRUE;
          } else
             $ret .= $string{$i};
        }
    }
    
    if ( $l ) {
        $string = "=?$default_charset?Q?$ret?=";
    }
    
    return( $string );
}

/*
    Strips dangerous tags from html messages.
*/
function MagicHTML( $body, $id ) {

    global $message, $PHP_SELF, $HTTP_SERVER_VARS;

    $j = strlen( $body );   // Legnth of the HTML
    $ret = '';              // Returned string
    $bgcolor = '#ffffff';   // Background style color (defaults to white)
    $textcolor = '#000000'; // Foreground style color (defaults to black)
    $leftmargin = '';       // Left margin style
    $title = '';            // HTML title if any

    $i = 0;
    while ( $i < $j ) {
        if ( $body{$i} == '<' ) {
            $pos = $i + 1;
            $tag = '';
            while ($body{$pos} == ' ' || $body{$pos} == "\t" ||
                   $body{$pos} == "\n") {
                $pos ++;
            }
            while (strlen($tag) < 4 && $body{$pos} != ' ' &&
                   $body{$pos} != "\t" && $body{$pos} != "\n") {
                $tag .= $body{$pos};
                $pos ++;
            }
            switch( strtoupper( $tag ) ) {
            // Strips the entire tag and contents
            case 'APPL':
            case 'EMBB':
            case 'FRAM':
            case 'SCRI':
            case 'OBJE':
                $etg = '/' . $tag;
                while ( $body{$i+1}.$body{$i+2}.$body{$i+3}.$body{$i+4}.$body{$i+5} <> $etg  &&
                       $i < $j  ) $i++;
                while ( $i < $j && $body{++$i} <> '>' );
                // $ret .= "<!-- $tag removed -->";
                break;
            // Substitute Title
            case 'TITL':
                $i += 5;
                while ( $body{$i} <> '>' &&  // </title>
                       $i < $j )
                        $i++;
                $i++;
                $title = '';
                while ( $body{$i} <> '<' &&  // </title>
                       $i < $j ) {
                    $title .= $body{$i};
                    $i++;
                }
                $i += 7;
                break;
            // Destroy these tags
            case 'HTML':
            case 'HEAD':
            case '/HTM':
            case '/HEA':
            case '!DOC':
            case 'META':
            case 'DIV ':
            case '/DIV':
            case '!-- ':
                $i += 4;
                while ( $body{$i}  <> '>' &&
                       $i < $j )
                    $i++;
                // $i++;
                break;
            case 'STYL':
                $i += 5;
                while ( $body{$i} <> '>' &&  // </title>
                       $i < $j )
                        $i++;
                $i++;
                // We parse the style to look for interesting stuff
                $styleblk = '';
                while ( $body{$i} <> '>' &&
                       $i < $j ) {
                    // First we get the name of the style
                    $style = '';
                    while ( $body{$i} <> '>' &&
                           $body{$i} <> '<' &&
                           $body{$i} <> '{' &&
                           $i < $j ) {
                       if ( isnoSep( $body{$i} ) )
                           $style .= $body{$i};
                       $i++;
                    }
                    stripComments( $i, $j, $body );
                    $style = strtoupper( trim( $style ) );
                    if ( $style == 'BODY' ) {
                        // Next we look into the definitions of the body style
                        while ( $body{$i} <> '>' &&
                               $body{$i} <> '}' &&
                               $i < $j ) {
                            // We look for the background color if any.
                            if ( substr( $body, $i, 17 ) == 'BACKGROUND-COLOR:' ) {
                                $i += 17;
                                $bgcolor = getStyleData( $i, $j, $body );
                            } elseif ( substr( $body, $i, 12 ) == 'MARGIN-LEFT:' ) {
                                $i += 12;
                                $leftmargin = getStyleData( $i, $j, $body );
                            }
                            $i++;
                        }
                    } else {
                        // Other style are mantained
                        $styleblk .= "$style ";
                        while ( $body{$i} <> '>' &&
                               $body{$i} <> '<' &&
                               $body{$i} <> '}' &&
                               $i < $j ) {
                            $styleblk .= $body{$i};
                            $i++;
                        }
                        $styleblk .= $body{$i};
                    }
                    stripComments( $i, $j, $body );
                    if ( $body{$i} <> '>' )
                        $i++;
                }
                if ( $styleblk <> '' )
                    $ret .= "<style>$styleblk";
                break;
            case 'BODY':
                if ( $title <> '' )
                    $ret .= '<b>' . _("Title:") . " </b>$title<br>\n";
                $ret .= "<TABLE";
                $i += 5;
                if (! isset($base)) {
                    $base = '';
                }
                $ret .= stripEvent( $i, $j, $body, $id, $base );
                $ret .= " bgcolor=$bgcolor width=\"100%\"><tr>";
                if ( $leftmargin <> '' )
                    $ret .= "<td width=$leftmargin>&nbsp;</td>";
                $ret .= '<td>';
                if (strtolower($bgcolor) == 'ffffff' ||
                    strtolower($bgcolor) == '#ffffff')
                    $ret .= '<font color=#000000>';
                break;
            case 'BASE':
                $i += 5;
                $base = '';
                while ( !isNoSep( $body{$i} ) &&
                       $i < $j ) {
                        $i++;
                }
                if ( strcasecmp( substr( $base, 0, 4 ), 'href'  ) ) {
                        $i += 5;
                        while ( !isNoSep( $body{$i} ) &&
                               $i < $j ) {
                                $i++;
                        }
                        while ( $body{$i} <> '>' &&
                               $i < $j ) {
                            if ( $body{$i} <> '"' ) {
                                $base .= $body{$i};
                            }
                            $i++;
                        }
                        // Debuging $ret .= "<!-- base == $base -->";
                        if ( strcasecmp( substr( $base, 0, 4 ), 'file' ) <> 0 ) {
                            $ret .= "\n<BASE HREF=\"$base\">\n";
                        }
                }
                break;
            case '/BOD':
                $ret .= '</font></td></tr></TABLE>';
                $i += 6;
                break;
            default:
                // Following tags can contain some event handler, lets search it
                stripComments( $i, $j, $body );
                if (! isset($base)) {
                   $base = '';
                }
                $ret .= stripEvent( $i, $j, $body, $id, $base ) . '>';
                        // $ret .= "<!-- $tag detected -->";
            }
        } else {
            $ret .= $body{$i};
        }
    $i++;
    }

return( "\n\n<!-- HTML Output ahead -->\n" .
        $ret .
        "\n<!-- END of HTML Output --><base href=\"".
        get_location() . '/'.
        "\">\n\n" );
}

function isNoSep( $char ) {

    switch( $char ) {
    case ' ':
    case "\n":
    case "\t":
    case "\r":
    case '>':
    case '"':
        return( FALSE );
        break;
    default:
        return( TRUE );
    }

}

/*
  The following function is usefull to remove extra data that can cause
  html not to display properly. Especialy with MS stuff.
*/

function stripComments( &$i, $j, &$body ) {

    while ( $body{$i}.$body{$i+1}.$body{$i+2}.$body{$i+3} == '<!--' &&
           $i < $j ) {
        $i += 5;
        while ( $body{$i-2}.$body{$i-1}.$body{$i} <> '-->' &&
               $i < $j )
            $i++;
        $i++;
    }

    return;

}

/* Gets the style data of a specific style */

function getStyleData( &$i, $j, &$body ) {

    // We skip spaces
    while ( $body{$i} <> '>' && !isNoSep( $body{$i} ) &&
           $i < $j ) {
        $i++;
    }
    // And get the color
    $ret = '';
    while ( isNoSep( $body{$i} ) &&
           $i < $j ) {
        $ret .= $body{$i};
        $i++;
    }

    return( $ret );
}

/*
Private function for strip_dangerous_tag. Look for event based coded and "remove" it
change on with no (onload -> noload)
*/

function stripEvent( &$i, $j, &$body, $id, $base ) {

    global $message, $base_uri;

    $ret = '';

    while ( $body{$i} <> '>' &&
           $i < $j ) {
        $etg = strtolower($body{$i}.$body{$i+1}.$body{$i+2});
        switch( $etg ) {
        case 'src':
            // This is probably a src specification
            $k = $i + 3;
            while( !isNoSep( $body{$k} )) {
                $k++;
            }
            if ( $body{$k} == '=' ) {
                /* It is indeed */
                $k++;
                while( !isNoSep( $body{$k} ) &&
                       $k < $j ) {
                    $k++;
                }
                $src = '';
                while ( $body{$k} <> '>' && isNoSep( $body{$k} ) &&
                       $k < $j ) {
                    $src .= $body{$k};
                    $k++;
                }
                while( !isNoSep( $body{$k} ) &&
                       $k < $j ) {
                    $k++;
                }
                if ( strtolower( substr( $src, 0, 4 ) ) == 'cid:' ) {
                    $src = substr( $src, 4 );
                    $src = "../src/download.php?absolute_dl=true&passed_id=$id&mailbox=" .
                           urlencode( $message->header->mailbox ) .
                           "&passed_ent_id=" . find_ent_id( $src, $message );                       
                } else if ( strtolower( substr( $src, 0, 4 ) ) <> 'http' || 
                            stristr( $src, $base_uri ) ) {
                    /* Javascript and local urls goes out */
                    $src = '../images/' . _("sec_remove_eng.png");
                }
                $ret .= 'src="' . $src . '" ';
                $i = $k - 3;
            } else {
                $ret .= 'src';
                $i = $i + 3;
            }
            
            break;
        case '../':
            // Retrolinks are not allowed without a base because they mess with SM security
            if ( $base == '' ) {
                    $i += 2;
            } else {
                    $ret .= '.';
            }
            break; 
        case 'cid':
            // Internal link
            $k = $i-1;
            if ( $body{$i+3} == ':') {
                $i +=4;
                $name = '';
                while ( isNoSep( $body{$i} ) &&
                       $i < $j  ) {
                    $name .= $body{$i++};
                }
                if ( $name <> '' ) {
                    $ret .= "../src/download.php?absolute_dl=true&passed_id=$id&mailbox=" .
                                urlencode( $message->header->mailbox ) .
                                "&passed_ent_id=" . find_ent_id( $name, $message );
                    if ( $body{$k} == '"' )
                        $ret .= '" ';
                    else
                        $ret .= ' ';
                }
                if ( $body{$i} == '>' )
                    $i -= 1;
            }
            break;
        case ' on':
        case "\non":
        case "\ron":
        case "\ton":
            $ret .= ' no';
            $i += 2;
            break;
        case 'pt:':
            if ( strcasecmp( $body{$i-4}.$body{$i-3}.$body{$i-2}.$body{$i-1}.$body{$i}.$body{$i+1}.$body{$i+2}, 'script:') == 0 ) {
                $ret .= '_no/';
            } else {
                $ret .= $etg;
            }
            $i += 2;
            break;
        default:
            $ret .= $body{$i};
        }
        $i++;
    }
    return( $ret );
}


/* This function trys to locate the entity_id of a specific mime element */

function find_ent_id( $id, $message ) {

    $ret = '';
    for ($i=0; $ret == '' && $i < count($message->entities); $i++) {

        if ( $message->entities[$i]->header->entity_id == '' ) {
            $ret = find_ent_id( $id, $message->entities[$i] );
        } else {
            if ( strcasecmp( $message->entities[$i]->header->id, $id ) == 0 )
                $ret = $message->entities[$i]->header->entity_id;
        }

    }

    return( $ret );

}
?>