functions/mime.php

   1 <?php
   2    /** mime.php
   3     **
   4     ** This contains the functions necessary to detect and decode MIME
   5     ** messages.
   6     **
   7     **/
   8
   9    $debug_mime = false;
  10    $mime_php = true;
  11
  12    if (!isset($i18n_php))
  13       include "../functions/i18n.php";
  14    if (!isset($imap_php))
  15       include "../functions/imap.php";
  16    if (!isset($config_php))
  17       include "../config/config.php";
  18
  19
  20    /** Setting up the objects that have the structure for the message **/
  21
  22    class msg_header {
  23       /** msg_header contains generic variables for values that **/
  24       /** could be in a header.                                 **/
  25
  26       var $type0, $type1, $boundary, $charset, $encoding, $size;
  27       var $to, $from, $date, $cc, $bcc, $reply_to, $subject;
  28       var $id, $mailbox, $description;
  29       var $entity_id, $message_id, $charset;
  30    }
  31
  32    class message {
  33       /** message is the object that contains messages.  It is a recursive
  34           object in that through the $entities variable, it can contain
  35           more objects of type message.  See documentation in mime.txt for
  36           a better description of how this works.
  37        **/
  38       var $header;
  39       var $entities;
  40
  41       function addEntity ($msg) {
  42          $this->entities[count($this->entities)] = $msg;
  43       }
  44    }
  45
  46
  47
  48    /* --------------------------------------------------------------------------------- */
  49    /* MIME DECODING                                                                     */
  50    /* --------------------------------------------------------------------------------- */
  51
  52    // This function gets the structure of a message and stores it in the "message" class.
  53    // It will return this object for use with all relevant header information and
  54    // fully parsed into the standard "message" object format.
  55    function mime_structure ($imap_stream, $header) {
  56       global $debug_mime;
  57       sqimap_messages_flag ($imap_stream, $header->id, $header->id, "Seen");
  58
  59       $id = $header->id;
  60       fputs ($imap_stream, "a001 FETCH $id BODYSTRUCTURE\r\n");
  61       $read = fgets ($imap_stream, 10000);
  62       $response = substr($read, 0, 4);
  63       while ($response != "a001") {
  64          $bodystructure .= $read;
  65          $read = fgets ($imap_stream, 10000);
  66          $response = substr($read, 0, 4);
  67       }
  68    //   $read = strtolower($bodystructure);
  69       $read = $bodystructure;
  70
  71       if ($debug_mime) echo "<tt>$read</tt><br><br>\n";
  72       // isolate the body structure and remove beginning and end parenthesis
  73       $read = trim(substr ($read, strpos(strtolower($read), "bodystructure") + 13));
  74       $read = trim(substr ($read, 0, -1));
  75       $end = mime_match_parenthesis(0, $read);
  76       while ($end == strlen($read)-1) {
  77          $read = trim(substr ($read, 0, -1));
  78          $read = trim(substr ($read, 1));
  79          $end = mime_match_parenthesis(0, $read);
  80       }
  81
  82       if ($debug_mime) echo "<tt>$read</tt><br><br>\n";
  83
  84       $msg = mime_parse_structure ($read, 0);
  85       $msg->header = $header;
  86       return $msg;
  87    }
  88
  89    // this starts the parsing of a particular structure.  It is called recursively,
  90    // so it can be passed different structures.  It returns an object of type
  91    // $message.
  92    // First, it checks to see if it is a multipart message.  If it is, then it
  93    // handles that as it sees is necessary.  If it is just a regular entity,
  94    // then it parses it and adds the necessary header information (by calling out
  95    // to mime_get_elements()
  96    function mime_parse_structure ($structure, $ent_id) {
  97       global $debug_mime;
  98       if ($debug_mime) echo "<font color=008800><tt>START: mime_parse_structure()</tt></font><br>\n";
  99       $msg = new message();
 100       if (substr($structure, 0, 1) == "(") {
 101          $ent_id = mime_new_element_level($ent_id);
 102          $start = $end = -1;
 103          if ($debug_mime) echo "<br><font color=0000aa><tt>$structure</tt></font><br>";
 104          do {
 105             if ($debug_mime) echo "<font color=008800><tt>Found entity...</tt></font><br>";
 106             $start = $end+1;
 107             $end = mime_match_parenthesis ($start, $structure);
 108
 109             $element = substr($structure, $start+1, ($end - $start)-1);
 110             $ent_id = mime_increment_id ($ent_id);
 111             $newmsg = mime_parse_structure ($element, $ent_id);
 112             $msg->addEntity ($newmsg);
 113          } while (substr($structure, $end+1, 1) == "(");
 114       } else {
 115          // parse the elements
 116          if ($debug_mime) echo "<br><font color=0000aa><tt>$structure</tt></font><br>";
 117          $msg = mime_get_element (&$structure, $msg, $ent_id);
 118          if ($debug_mime) echo "<br>";
 119       }
 120       return $msg;
 121       if ($debug_mime) echo "<font color=008800><tt>&nbsp;&nbsp;END: mime_parse_structure()</tt></font><br>";
 122    }
 123
 124    // Increments the element ID.  An element id can look like any of
 125    // the following:  1, 1.2, 4.3.2.4.1, etc.  This function increments
 126    // the last number of the element id, changing 1.2 to 1.3.
 127    function mime_increment_id ($id) {
 128       global $debug_mime;
 129       if (strpos($id, ".")) {
 130          $first = substr($id, 0, strrpos($id, "."));
 131          $last = substr($id, strrpos($id, ".")+1);
 132          $last++;
 133          $new = $first . "." .$last;
 134       } else {
 135          $new = $id + 1;
 136       }
 137       if ($debug_mime) echo "<b>INCREMENT: $new</b><br>";
 138       return $new;
 139    }
 140
 141    // See comment for mime_increment_id().
 142    // This adds another level on to the entity_id changing 1.3 to 1.3.0
 143    // NOTE:  1.3.0 is not a valid element ID.  It MUST be incremented
 144    //        before it can be used.  I left it this way so as not to have
 145    //        to make a special case if it is the first entity_id.  It
 146    //        always increments it, and that works fine.
 147    function mime_new_element_level ($id) {
 148       if (!$id) $id = 0;
 149       else      $id = $id . ".0";
 150
 151       return $id;
 152    }
 153
 154    function mime_get_element (&$structure, $msg, $ent_id) {
 155       global $debug_mime;
 156       $elem_num = 1;
 157       $msg->header = new msg_header();
 158       $msg->header->entity_id = $ent_id;
 159
 160       while (strlen($structure) > 0) {
 161          $structure = trim($structure);
 162          $char = substr($structure, 0, 1);
 163
 164          if (strtolower(substr($structure, 0, 3)) == "nil") {
 165             $text = "";
 166             $structure = substr($structure, 3);
 167          } else if ($char == "\"") {
 168             // loop through until we find the matching quote, and return that as a string
 169             $pos = 1;
 170             $char = substr($structure, $pos, 1);
 171             while ($char != "\"" && $pos < strlen($structure)) {
 172                $text .= $char;
 173                $pos++;
 174                $char = substr($structure, $pos, 1);
 175             }
 176             $structure = substr($structure, strlen($text) + 2);
 177          } else if ($char == "(") {
 178             // comment me
 179             $end = mime_match_parenthesis (0, $structure);
 180             $sub = substr($structure, 1, $end-1);
 181             $properties = mime_get_props($properties, $sub);
 182             $structure = substr($structure, strlen($sub) + 2);
 183          } else {
 184             // loop through until we find a space or an end parenthesis
 185             $pos = 0;
 186             $char = substr($structure, $pos, 1);
 187             while ($char != " " && $char != ")" && $pos < strlen($structure)) {
 188                $text .= $char;
 189                $pos++;
 190                $char = substr($structure, $pos, 1);
 191             }
 192             $structure = substr($structure, strlen($text));
 193          }
 194          if ($debug_mime) echo "<tt>$elem_num : $text</tt><br>";
 195
 196          // This is where all the text parts get put into the header
 197          switch ($elem_num) {
 198             case 1:
 199                $msg->header->type0 = strtolower($text);
 200                if ($debug_mime) echo "<tt>type0 = ".strtolower($text)."</tt><br>";
 201                break;
 202             case 2:
 203                $msg->header->type1 = strtolower($text);
 204                if ($debug_mime) echo "<tt>type1 = ".strtolower($text)."</tt><br>";
 205                break;
 206             case 5:
 207                $msg->header->description = $text;
 208                if ($debug_mime) echo "<tt>description = $text</tt><br>";
 209                break;
 210             case 6:
 211                $msg->header->encoding = strtolower($text);
 212                if ($debug_mime) echo "<tt>encoding = ".strtolower($text)."</tt><br>";
 213                break;
 214             case 7:
 215                $msg->header->size = $text;
 216                if ($debug_mime) echo "<tt>size = $text</tt><br>";
 217                break;
 218             default:
 219                if ($msg->header->type0 == "text" && $elem_num == 8) {
 220                   // This is a plain text message, so lets get the number of lines
 221                   // that it contains.
 222                   $msg->header->num_lines = $text;
 223                   if ($debug_mime) echo "<tt>num_lines = $text</tt><br>";
 224
 225                } else if ($msg->header->type0 == "message" && $msg->header->type1 == "rfc822" && $elem_num == 8) {
 226                   // This is an encapsulated message, so lets start all over again and
 227                   // parse this message adding it on to the existing one.
 228                   $structure = trim($structure);
 229                   if (substr($structure, 0, 1) == "(") {
 230                      $e = mime_match_parenthesis (0, $structure);
 231                      $structure = substr($structure, 0, $e);
 232                      $structure = substr($structure, 1);
 233                      $m = mime_parse_structure($structure, $msg->header->entity_id);
 234
 235                      // the following conditional is there to correct a bug that wasn't
 236                      // incrementing the entity IDs correctly because of the special case
 237                      // that message/rfc822 is.  This fixes it fine.
 238                      if (substr($structure, 1, 1) != "(")
 239                         $m->header->entity_id = mime_increment_id(mime_new_element_level($ent_id));
 240
 241                      // Now we'll go through and reformat the results.
 242                      if ($m->entities) {
 243                         for ($i=0; $i < count($m->entities); $i++) {
 244                            $msg->addEntity($m->entities[$i]);
 245                         }
 246                      } else {
 247                         $msg->addEntity($m);
 248                      }
 249                      $structure = "";
 250                   }
 251                }
 252                break;
 253          }
 254          $elem_num++;
 255          $text = "";
 256       }
 257       // loop through the additional properties and put those in the various headers
 258       if ($msg->header->type0 != "message") {
 259          for ($i=0; $i < count($properties); $i++) {
 260             $msg->header->{$properties[$i]["name"]} = $properties[$i]["value"];
 261             if ($debug_mime) echo "<tt>".$properties[$i]["name"]." = " . $properties[$i]["value"] . "</tt><br>";
 262          }
 263       }
 264
 265       return $msg;
 266    }
 267
 268    // I did most of the MIME stuff yesterday (June 20, 2000), but I couldn't
 269    // figure out how to do this part, so I decided to go to bed.  I woke up
 270    // in the morning and had a flash of insight.  I went to the white-board
 271    // and scribbled it out, then spent a bit programming it, and this is the
 272    // result.  Nothing complicated, but I think my brain was fried yesterday.
 273    // Funny how that happens some times.
 274    //
 275    // This gets properties in a nested parenthesisized list.  For example,
 276    // this would get passed something like:  ("attachment" ("filename" "luke.tar.gz"))
 277    // This returns an array called $props with all paired up properties.
 278    // It ignores the "attachment" for now, maybe that should change later
 279    // down the road.  In this case, what is returned is:
 280    //    $props[0]["name"] = "filename";
 281    //    $props[0]["value"] = "luke.tar.gz";
 282    function mime_get_props ($props, $structure) {
 283       global $debug_mime;
 284       while (strlen($structure) > 0) {
 285          $structure = trim($structure);
 286          $char = substr($structure, 0, 1);
 287
 288          if ($char == "\"") {
 289             $pos = 1;
 290             $char = substr($structure, $pos, 1);
 291             while ($char != "\"" && $pos < strlen($structure)) {
 292                $tmp .= $char;
 293                $pos++;
 294                $char = substr($structure, $pos, 1);
 295             }
 296             $structure = trim(substr($structure, strlen($tmp) + 2));
 297             $char = substr($structure, 0, 1);
 298
 299             if ($char == "\"") {
 300                $pos = 1;
 301                $char = substr($structure, $pos, 1);
 302                while ($char != "\"" && $pos < strlen($structure)) {
 303                   $value .= $char;
 304                   $pos++;
 305                   $char = substr($structure, $pos, 1);
 306                }
 307                $structure = trim(substr($structure, strlen($tmp) + 2));
 308
 309                $k = count($props);
 310                $props[$k]["name"] = strtolower($tmp);
 311                $props[$k]["value"] = $value;
 312             } else if ($char == "(") {
 313                $end = mime_match_parenthesis (0, $structure);
 314                $sub = substr($structure, 1, $end-1);
 315                $props = mime_get_props($props, $sub);
 316                $structure = substr($structure, strlen($sub) + 2);
 317             }
 318             return $props;
 319          } else if ($char == "(") {
 320             $end = mime_match_parenthesis (0, $structure);
 321             $sub = substr($structure, 1, $end-1);
 322             $props = mime_get_props($props, $sub);
 323             $structure = substr($structure, strlen($sub) + 2);
 324             return $props;
 325          } else {
 326             return $props;
 327          }
 328       }
 329    }
 330
 331    //  Matches parenthesis.  It will return the position of the matching
 332    //  parenthesis in $structure.  For instance, if $structure was:
 333    //     ("text" "plain" ("val1name", "1") nil ... )
 334    //     x                                         x
 335    //  then this would return 42 to match up those two.
 336    function mime_match_parenthesis ($pos, $structure) {
 337       $char = substr($structure, $pos, 1);
 338
 339       // ignore all extra characters
 340       // If inside of a string, skip string -- Boundary IDs and other
 341       // things can have ) in them.
 342       while ($pos < strlen($structure)) {
 343          $pos++;
 344          $char = substr($structure, $pos, 1);
 345          if ($char == ")") {
 346             return $pos;
 347          } else if ($char == '"') {
 348             $pos ++;
 349             while (substr($structure, $pos, 1) != '"' &&
 350                $pos < strlen($structure)) {
 351                $pos ++;
 352             }
 353          } else if ($char == "(") {
 354             $pos = mime_match_parenthesis ($pos, $structure);
 355          }
 356       }
 357    }
 358
 359    function mime_fetch_body ($imap_stream, $id, $ent_id) {
 360       // do a bit of error correction.  If we couldn't find the entity id, just guess
 361       // that it is the first one.  That is usually the case anyway.
 362       if (!$ent_id) $ent_id = 1;
 363
 364       fputs ($imap_stream, "a001 FETCH $id BODY[$ent_id]\r\n");
 365       $topline = fgets ($imap_stream, 1024);
 366       $size = substr ($topline, strpos($topline, "{")+1);
 367       $size = substr ($size, 0, strpos($size, "}"));
 368       $read = fread ($imap_stream, $size);
 369       return $read;
 370    }
 371
 372    /* -[ END MIME DECODING ]----------------------------------------------------------- */
 373
 374
 375
 376    /** This is the first function called.  It decides if this is a multipart
 377        message or if it should be handled as a single entity
 378     **/
 379    function decodeMime ($imap_stream, $body, $header) {
 380       global $username, $key, $imapServerAddress, $imapPort;
 381       return mime_structure ($imap_stream, $header);
 382    }
 383
 384    // This is here for debugging purposese.  It will print out a list
 385    // of all the entity IDs that are in the $message object.
 386    function listEntities ($message) {
 387       if ($message) {
 388          if ($message->header->entity_id)
 389          echo "<tt>" . $message->header->entity_id . " : " . $message->header->type0 . "/" . $message->header->type1 . "<br>";
 390          for ($i = 0; $message->entities[$i]; $i++) {
 391             $msg = listEntities($message->entities[$i], $ent_id);
 392             if ($msg)
 393                return $msg;
 394          }
 395       }
 396    }
 397
 398    // returns a $message object for a particular entity id
 399    function getEntity ($message, $ent_id) {
 400       if ($message) {
 401          if ($message->header->entity_id == $ent_id && strlen($ent_id) == strlen($message->header->entity_id)) {
 402             return $message;
 403          } else {
 404             for ($i = 0; $message->entities[$i]; $i++) {
 405                $msg = getEntity ($message->entities[$i], $ent_id);
 406                if ($msg)
 407                   return $msg;
 408             }
 409          }
 410       }
 411    }
 412
 413    // figures out what entity to display and returns the $message object
 414    // for that entity.
 415    function findDisplayEntity ($message) {
 416       if ($message) {
 417          if ($message->header->type0 == "text") {
 418             if ($message->header->type1 == "plain" ||
 419                 $message->header->type1 == "html") {
 420                return $message->header->entity_id;
 421             }
 422          } else {
 423             for ($i=0; $message->entities[$i]; $i++) {
 424                return findDisplayEntity($message->entities[$i]);
 425             }
 426          }
 427       }
 428    }
 429
 430    /** This returns a parsed string called $body. That string can then
 431        be displayed as the actual message in the HTML. It contains
 432        everything needed, including HTML Tags, Attachments at the
 433        bottom, etc.
 434     **/
 435    function formatBody($imap_stream, $message, $color, $wrap_at) {
 436       // this if statement checks for the entity to show as the
 437       // primary message. To add more of them, just put them in the
 438       // order that is their priority.
 439       global $startMessage, $username, $key, $imapServerAddress, $imapPort;
 440
 441       $id = $message->header->id;
 442       $urlmailbox = urlencode($message->header->mailbox);
 443
 444       // Get the right entity and redefine message to be this entity
 445       $ent_num = findDisplayEntity ($message);
 446       $body_message = getEntity($message, $ent_num);
 447       if (($body_message->header->type0 == "text") ||
 448           ($body_message->header->type0 == "rfc822")) {
 449
 450          $body = mime_fetch_body ($imap_stream, $id, $ent_num);
 451          $body = decodeBody($body, $body_message->header->encoding);
 452
 453          // If there are other types that shouldn't be formatted, add
 454          // them here
 455          if ($message->header->type1 != "html") {
 456             $body = translateText($body, $wrap_at, $body_message->header->charset);
 457          }
 458
 459          $body .= "<SMALL><CENTER><A HREF=\"../src/download.php?absolute_dl=true&passed_id=$id&passed_ent_id=$ent_num&mailbox=$urlmailbox\">". _("Download this as a file") ."</A></CENTER><BR></SMALL>";
 460
 461          /** Display the ATTACHMENTS: message if there's more than one part **/
 462          $body .= "</TD></TR></TABLE>";
 463          if ($message->entities) {
 464             $body .= formatAttachments ($message, $ent_num, $message->header->mailbox, $id);
 465          }
 466       } else {
 467          $body .= formatAttachments ($message, -1, $message->header->mailbox, $id);
 468       }
 469       return $body;
 470    }
 471
 472    // A recursive function that returns a list of attachments with links
 473    // to where to download these attachments
 474    function formatAttachments ($message, $ent_id, $mailbox, $id) {
 475       global $where, $what;
 476       global $startMessage, $color;
 477       static $ShownHTML;
 478
 479       if ($ShownHTML == 0)
 480       {
 481             $ShownHTML = 1;
 482
 483             $body .= "<TABLE WIDTH=100% CELLSPACING=0 CELLPADDING=2 BORDER=0 BGCOLOR=\"$color[0]\"><TR>\n";
 484             $body .= "<TH ALIGN=\"left\" BGCOLOR=\"$color[9]\"><B>\n";
 485             $body .= _('Attachments') . ':';
 486             $body .= "</B></TH></TR><TR><TD>\n";
 487
 488             $body .= "<TABLE CELLSPACING=0 CELLPADDING=1 BORDER=0>\n";
 489
 490             $body .= formatAttachments ($message, $ent_id, $mailbox, $id);
 491
 492             $body .= "</TABLE></TD></TR></TABLE>";
 493
 494             return $body;
 495       }
 496
 497       if ($message) {
 498          if (!$message->entities) {
 499             $type0 = strtolower($message->header->type0);
 500             $type1 = strtolower($message->header->type1);
 501
 502             if ($message->header->entity_id != $ent_id) {
 503                $filename = decodeHeader($message->header->filename);
 504                if (trim($filename) == "") {
 505                   $display_filename = "untitled-".$message->header->entity_id;
 506                } else {
 507                   $display_filename = $filename;
 508                }
 509
 510                $urlMailbox = urlencode($mailbox);
 511                $ent = urlencode($message->header->entity_id);
 512
 513                $DefaultLink =
 514                   "../src/download.php?startMessage=$startMessage&passed_id=$id&mailbox=$urlMailbox&passed_ent_id=$ent";
 515                if ($where && $what)
 516                   $DefaultLink .= '&where=' . urlencode($where) . '&what=' . urlencode($what);
 517                $Links['download link']['text'] = _('download');
 518                $Links['download link']['href'] =
 519                    "../src/download.php?absolute_dl=true&passed_id=$id&mailbox=$urlMailbox&passed_ent_id=$ent";
 520                $ImageURL = '';
 521
 522                $HookResults = do_hook("attachment $type0/$type1", $Links,
 523                    $startMessage, $id, $urlMailbox, $ent, $DefaultLink,
 524                    $where, $what);
 525
 526                $Links = $HookResults[1];
 527                $DefaultLink = $HookResults[6];
 528
 529                $body .= '<TR><TD>&nbsp;&nbsp;</TD><TD>';
 530                $body .= "<A HREF=\"$DefaultLink\">$display_filename</A>&nbsp;</TD>";
 531                $size = $message->header->size / 1024;
 532                settype($size, "integer");
 533                $body .= "<TD><SMALL><b>" . $size . "k</b>&nbsp;&nbsp;</small></TD>";
 534                $body .= "<TD><SMALL>[ $type0/$type1 ]&nbsp;</SMALL></TD>";
 535                $body .= '<TD><SMALL>';
 536                if ($message->header->description)
 537                   $body .= '<b>' . htmlspecialchars($message->header->description) . '</b>';
 538                $body .= '</SMALL></TD><TD><SMALL>&nbsp;';
 539
 540
 541                $SkipSpaces = 1;
 542                foreach ($Links as $Val)
 543                {
 544                   if ($SkipSpaces)
 545                   {
 546                      $SkipSpaces = 0;
 547                   }
 548                   else
 549                   {
 550                      $body .= '&nbsp;&nbsp;|&nbsp;&nbsp;';
 551                   }
 552                   $body .= '<a href="' . $Val['href'] . '">' .  $Val['text'] . '</a>';
 553                }
 554
 555                unset($Links);
 556
 557                $body .= "</SMALL></TD></TR>\n";
 558             }
 559             return $body;
 560          } else {
 561             for ($i = 0; $i < count($message->entities); $i++) {
 562                $body .= formatAttachments ($message->entities[$i], $ent_id, $mailbox, $id);
 563             }
 564             return $body;
 565          }
 566       }
 567    }
 568
 569
 570    /** this function decodes the body depending on the encoding type. **/
 571    function decodeBody($body, $encoding) {
 572       $body = str_replace("\r\n", "\n", $body);
 573       $encoding = strtolower($encoding);
 574
 575       if ($encoding == "quoted-printable") {
 576          $body = quoted_printable_decode($body);
 577
 578          while (ereg("=\n", $body))
 579             $body = ereg_replace ("=\n", "", $body);
 580       } else if ($encoding == "base64") {
 581          $body = base64_decode($body);
 582       }
 583
 584       // All other encodings are returned raw.
 585       return $body;
 586    }
 587
 588
 589    // This functions decode strings that is encoded according to
 590    // RFC1522 (MIME Part Two: Message Header Extensions for Non-ASCII Text).
 591    function decodeHeader ($string) {
 592       if (eregi('=\?([^?]+)\?(q|b)\?([^?]+)\?=',
 593                 $string, $res)) {
 594          if (ucfirst($res[2]) == "B") {
 595             $replace = base64_decode($res[3]);
 596          } else {
 597             $replace = ereg_replace("_", " ", $res[3]);
 598             // Convert lowercase Quoted Printable to uppercase for
 599             // quoted_printable_decode to understand it.
 600             while (ereg("(=([0-9][a-f])|([a-f][0-9])|([a-f][0-9]))", $replace, $res)) {
 601                $replace = str_replace($res[1], strtoupper($res[1]), $replace);
 602             }
 603             $replace = quoted_printable_decode($replace);
 604          }
 605
 606          $replace = charset_decode ($res[1], $replace);
 607
 608          $string = eregi_replace
 609             ('=\?([^?]+)\?(q|b)\?([^?]+)\?=',
 610              $replace, $string);
 611          // In case there should be more encoding in the string: recurse
 612          return (decodeHeader($string));
 613       } else
 614          return ($string);
 615    }
 616
 617    // Encode a string according to RFC 1522 for use in headers if it
 618    // contains 8-bit characters or anything that looks like it should
 619    // be encoded.
 620    function encodeHeader ($string) {
 621       global $default_charset;
 622
 623       // Encode only if the string contains 8-bit characters or =?
 624       if (ereg("([\200-\377])|=\\?", $string)) {
 625          $newstring = "=?$default_charset?Q?";
 626
 627          // First the special characters
 628          $string = str_replace("=", "=3D", $string);
 629          $string = str_replace("?", "=3F", $string);
 630          $string = str_replace("_", "=5F", $string);
 631          $string = str_replace(" ", "_", $string);
 632
 633
 634          while (ereg("([\200-\377])", $string, $regs)) {
 635             $replace = $regs[1];
 636             $insert = "=" . strtoupper(bin2hex($replace));
 637             $string = str_replace($replace, $insert, $string);
 638          }
 639
 640          $newstring = "=?$default_charset?Q?".$string."?=";
 641
 642          return $newstring;
 643       }
 644
 645       return $string;
 646    }
 647
 648 ?>