----------------global.php----------------------------

if (isset($_REQUEST['attachmentid'])) $attachmentid = $_REQUEST['attachmentid'];


if (isset($attachmentid)) {
	$attachmentid = intval($attachmentid);
	$attachment = $db->query_first("SELECT bb".$n."_attachments.*, bb".$n."_threads.boardid, bb".$n."_posts.threadid, bb".$n."_posts.visible, bb".$n."_posts.userid FROM bb".$n."_attachments LEFT JOIN bb".$n."_posts ON (bb".$n."_posts.postid=bb".$n."_attachments.postid) LEFT JOIN bb".$n."_threads ON (bb".$n."_threads.threadid=bb".$n."_posts.threadid) WHERE bb".$n."_attachments.attachmentid = '$attachmentid'");
	if (!$attachment['attachmentid']) unset($attachmentid);
	elseif ($attachment['boardid']) {
		$boardid = $attachment['boardid'];
		$threadid = $attachment['threadid'];
		unset($thread);
	}

--------------attachment.php------------------------------

<?php
$filename = 'attachment.php';

require('./global.php');

if (checkpermissions('can_download_attachments') == 0) access_error();

if (isset($attachmentid)) {
	$db->unbuffered_query("UPDATE bb".$n."_attachments SET counter=counter+1 WHERE attachmentid = '$attachmentid'", 1); 

	if (preg_match('/MSIE [0-9]\.[0-9]{1,2}/', $_SERVER['HTTP_USER_AGENT'])) $browser_type = 1; // IE 
	else if (preg_match('/Opera\/[0-9]\.[0-9]{1,2}/', $_SERVER['HTTP_USER_AGENT'])) $browser_type = 2; // Opera
	else $browser_type = 3; // other...

	$content_disp = '';
	$extension = $attachment['attachmentextension'];
	if ($extension == 'gif') $mime_type = 'image/gif';
	elseif ($extension == 'jpg' || $extension == 'jpeg') $mime_type = 'image/jpeg';
	elseif ($extension == 'png') $mime_type = 'image/png';
	elseif ($extension == 'pdf') $mime_type = 'application/pdf';
	else {
		if ($browser_type == 1 || $browser_type == 2) $mime_type = 'application/octetstream';
		else $mime_type = 'application/octet-stream';

		if ($browser_type == 1) $content_disp = 'inline; ';
		else $content_disp = 'attachment; ';
	}
	header('Content-Type: '.$mime_type);
	header('Content-disposition: '.$content_disp.'filename="'.$attachment['attachmentname'].'.'.$attachment['attachmentextension'].'"');

	if ($browser_type == 1) header('Pragma: public');
	else header('Pragma: no-cache');

	header('Expires: 0');
	readfile("attachments/attachment-".$attachment['attachmentid'].".".$attachment['attachmentextension']);
}
else error($lang->get("LANG_GLOBAL_ERROR_FALSELINK", array('$adminmail' => $adminmail)));
?>