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simple-machines-forum/Sources/ShowAttachments.php

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<?php
/**
* This file handles avatar and attachment requests. The whole point of this file is to reduce the loaded stuff to show an image.
*
* Simple Machines Forum (SMF)
*
* @package SMF
* @author Simple Machines https://www.simplemachines.org
* @copyright 2022 Simple Machines and individual contributors
* @license https://www.simplemachines.org/about/smf/license.php BSD
*
* @version 2.1.3
*/
if (!defined('SMF'))
die('No direct access...');
/**
* Downloads an avatar or attachment based on $_GET['attach'], and increments the download count.
* It requires the view_attachments permission.
* It disables the session parser, and clears any previous output.
* It depends on the attachmentUploadDir setting being correct.
* It is accessed via the query string ?action=dlattach.
* Views to attachments do not increase hits and are not logged in the "Who's Online" log.
*/
function showAttachment()
{
global $smcFunc, $modSettings, $maintenance, $context, $txt, $user_info;
// Some defaults that we need.
$context['character_set'] = empty($modSettings['global_character_set']) ? (empty($txt['lang_character_set']) ? 'ISO-8859-1' : $txt['lang_character_set']) : $modSettings['global_character_set'];
$context['utf8'] = $context['character_set'] === 'UTF-8';
// An early hook to set up global vars, clean cache and other early process.
call_integration_hook('integrate_pre_download_request');
// This is done to clear any output that was made before now.
ob_end_clean();
header_remove('content-encoding');
if (!empty($modSettings['enableCompressedOutput']) && !headers_sent() && ob_get_length() == 0)
{
if (@ini_get('zlib.output_compression') == '1' || @ini_get('output_handler') == 'ob_gzhandler')
$modSettings['enableCompressedOutput'] = 0;
else
ob_start('ob_gzhandler');
}
if (empty($modSettings['enableCompressedOutput']))
{
ob_start();
header('content-encoding: none');
}
// Better handling.
$attachId = $_REQUEST['attach'] = isset($_REQUEST['attach']) ? (int) $_REQUEST['attach'] : (int) (isset($_REQUEST['id']) ? (int) $_REQUEST['id'] : 0);
// We need a valid ID.
if (empty($attachId))
{
send_http_status(404, 'File Not Found');
die('404 File Not Found');
}
// A thumbnail has been requested? madness! madness I say!
$showThumb = isset($_REQUEST['thumb']);
// No access in strict maintenance mode.
if (!empty($maintenance) && $maintenance == 2)
{
send_http_status(404, 'File Not Found');
die('404 File Not Found');
}
// Use cache when possible.
if (($cache = cache_get_data('attachment_lookup_id-' . $attachId)) != null)
list ($file, $thumbFile) = $cache;
// Get the info from the DB.
if (empty($file) || empty($thumbFile) && !empty($file['id_thumb']))
{
// Do we have a hook wanting to use our attachment system? We use $attachRequest to prevent accidental usage of $request.
$attachRequest = null;
call_integration_hook('integrate_download_request', array(&$attachRequest));
if (!is_null($attachRequest) && $smcFunc['db_is_resource']($attachRequest))
$request = $attachRequest;
else
{
// Make sure this attachment is on this board and load its info while we are at it.
$request = $smcFunc['db_query']('', '
SELECT
{string:source} AS source,
a.id_folder, a.filename, a.file_hash, a.fileext, a.id_attach,
a.id_thumb, a.attachment_type, a.mime_type, a.approved, a.id_msg,
m.id_board
FROM {db_prefix}attachments AS a
LEFT JOIN {db_prefix}messages AS m ON (m.id_msg = a.id_msg)
WHERE a.id_attach = {int:attach}
LIMIT 1',
array(
'source' => 'SMF',
'attach' => $attachId,
)
);
}
// No attachment has been found.
if ($smcFunc['db_num_rows']($request) == 0)
{
send_http_status(404, 'File Not Found');
die('404 File Not Found');
}
$file = $smcFunc['db_fetch_assoc']($request);
$smcFunc['db_free_result']($request);
// set filePath and ETag time
$file['filePath'] = getAttachmentFilename($file['filename'], $attachId, $file['id_folder'], false, $file['file_hash']);
// ensure variant attachment compatibility
$filePath = pathinfo($file['filePath']);
$file['exists'] = file_exists($file['filePath']);
$file['filePath'] = !$file['exists'] && isset($filePath['extension']) ? substr($file['filePath'], 0, -(strlen($filePath['extension']) + 1)) : $file['filePath'];
$file['mtime'] = $file['exists'] ? filemtime($file['filePath']) : 0;
$file['size'] = $file['exists'] ? filesize($file['filePath']) : 0;
$file['etag'] = $file['exists'] ? sha1_file($file['filePath']) : '';
// now get the thumbfile!
$thumbFile = array();
if (!empty($file['id_thumb']))
{
$request = $smcFunc['db_query']('', '
SELECT id_folder, filename, file_hash, fileext, id_attach, attachment_type, mime_type, approved, id_member
FROM {db_prefix}attachments
WHERE id_attach = {int:thumb_id}
LIMIT 1',
array(
'thumb_id' => $file['id_thumb'],
)
);
$thumbFile = $smcFunc['db_fetch_assoc']($request);
$smcFunc['db_free_result']($request);
// Got something! replace the $file var with the thumbnail info.
if ($thumbFile)
{
$thumbFile['filePath'] = getAttachmentFilename($thumbFile['filename'], $thumbFile['id_attach'], $thumbFile['id_folder'], false, $thumbFile['file_hash']);
$thumbPath = pathinfo($thumbFile['filePath']);
// set filePath and ETag time
$thumbFile['exists'] = file_exists($thumbFile['filePath']);
$thumbFile['filePath'] = !$thumbFile['exists'] && isset($thumbPath['extension']) ? substr($thumbFile['filePath'], 0, -(strlen($thumbPath['extension']) + 1)) : $thumbFile['filePath'];
$thumbFile['mtime'] = $thumbFile['exists'] ? filemtime($thumbFile['filePath']) : 0;
$thumbFile['size'] = $thumbFile['exists'] ? filesize($thumbFile['filePath']) : 0;
$thumbFile['etag'] = $thumbFile['exists'] ? sha1_file($thumbFile['filePath']) : '';
}
}
// Cache it.
if (!empty($file) || !empty($thumbFile))
cache_put_data('attachment_lookup_id-' . $file['id_attach'], array($file, $thumbFile), mt_rand(850, 900));
}
// Can they see attachments on this board?
if (!empty($file['id_msg']))
{
// Special case for profile exports.
if (!empty($context['attachment_allow_hidden_boards']))
{
$boards_allowed = array(0);
}
// Check permissions and board access.
elseif (($boards_allowed = cache_get_data('view_attachment_boards_id-' . $user_info['id'])) == null)
{
$boards_allowed = boardsAllowedTo('view_attachments');
cache_put_data('view_attachment_boards_id-' . $user_info['id'], $boards_allowed, mt_rand(850, 900));
}
}
// No access if you don't have permission to see this attachment.
if
(
// This was from SMF or a hook didn't claim it.
(
empty($file['source'])
|| $file['source'] == 'SMF'
)
&& (
// No id_msg and no id_member, so we don't know where its from.
// Avatars will have id_msg = 0 and id_member > 0.
(
empty($file['id_msg'])
&& empty($file['id_member'])
)
// When we have a message, we need a board and that board needs to
// let us view the attachment.
|| (
!empty($file['id_msg'])
&& (
empty($file['id_board'])
|| ($boards_allowed !== array(0) && !in_array($file['id_board'], $boards_allowed))
)
)
)
// We are not previewing an attachment.
&& !isset($_SESSION['attachments_can_preview'][$attachId])
)
{
send_http_status(404, 'File Not Found');
die('404 File Not Found');
}
// If attachment is unapproved, see if user is allowed to approve
if (!$file['approved'] && $modSettings['postmod_active'] && !allowedTo('approve_posts'))
{
$request = $smcFunc['db_query']('', '
SELECT id_member
FROM {db_prefix}messages
WHERE id_msg = {int:id_msg}
LIMIT 1',
array(
'id_msg' => $file['id_msg'],
)
);
$id_member = $smcFunc['db_fetch_assoc']($request)['id_member'];
$smcFunc['db_free_result']($request);
// Let users see own unapproved attachments
if ($id_member != $user_info['id'])
{
send_http_status(403, 'Forbidden');
die('403 Forbidden');
}
}
// Replace the normal file with its thumbnail if it has one!
if (!empty($showThumb) && !empty($thumbFile))
$file = $thumbFile;
// No point in a nicer message, because this is supposed to be an attachment anyway...
if (empty($file['exists']))
{
send_http_status(404);
header('content-type: text/plain; charset=' . (empty($context['character_set']) ? 'ISO-8859-1' : $context['character_set']));
// We need to die like this *before* we send any anti-caching headers as below.
die('File not found.');
}
// If it hasn't been modified since the last time this attachment was retrieved, there's no need to display it again.
if (!empty($_SERVER['HTTP_IF_MODIFIED_SINCE']))
{
list($modified_since) = explode(';', $_SERVER['HTTP_IF_MODIFIED_SINCE']);
if (!empty($file['mtime']) && strtotime($modified_since) >= $file['mtime'])
{
ob_end_clean();
header_remove('content-encoding');
// Answer the question - no, it hasn't been modified ;).
send_http_status(304);
exit;
}
}
// Check whether the ETag was sent back, and cache based on that...
if (!empty($file['etag']) && !empty($_SERVER['HTTP_IF_NONE_MATCH']) && strpos($_SERVER['HTTP_IF_NONE_MATCH'], $file['etag']) !== false)
{
ob_end_clean();
header_remove('content-encoding');
send_http_status(304);
exit;
}
// If this is a partial download, we need to determine what data range to send
$range = 0;
if (isset($_SERVER['HTTP_RANGE']))
{
list($a, $range) = explode("=", $_SERVER['HTTP_RANGE'], 2);
list($range) = explode(",", $range, 2);
list($range, $range_end) = explode("-", $range);
$range = intval($range);
$range_end = !$range_end ? $file['size'] - 1 : intval($range_end);
$new_length = $range_end - $range + 1;
}
// Update the download counter (unless it's a thumbnail or resuming an incomplete download).
if ($file['attachment_type'] != 3 && empty($showThumb) && $range === 0 && empty($context['skip_downloads_increment']))
$smcFunc['db_query']('', '
UPDATE {db_prefix}attachments
SET downloads = downloads + 1
WHERE id_attach = {int:id_attach}',
array(
'id_attach' => $attachId,
)
);
// Send the attachment headers.
header('pragma: ');
if (!isBrowser('gecko'))
header('content-transfer-encoding: binary');
header('expires: ' . gmdate('D, d M Y H:i:s', time() + 525600 * 60) . ' GMT');
header('last-modified: ' . gmdate('D, d M Y H:i:s', $file['mtime']) . ' GMT');
header('accept-ranges: bytes');
header('connection: close');
header('etag: "' . $file['etag'] . '"');
// Make sure the mime type warrants an inline display.
if (isset($_REQUEST['image']) && !empty($file['mime_type']) && strpos($file['mime_type'], 'image/') !== 0)
unset($_REQUEST['image']);
// Does this have a mime type?
elseif (!empty($file['mime_type']) && (isset($_REQUEST['image']) || !in_array($file['fileext'], array('jpg', 'gif', 'jpeg', 'x-ms-bmp', 'png', 'psd', 'tiff', 'iff'))))
header('content-type: ' . strtr($file['mime_type'], array('image/bmp' => 'image/x-ms-bmp')));
else
{
header('content-type: ' . (isBrowser('ie') || isBrowser('opera') ? 'application/octetstream' : 'application/octet-stream'));
if (isset($_REQUEST['image']))
unset($_REQUEST['image']);
}
// Convert the file to UTF-8, cuz most browsers dig that.
$utf8name = !$context['utf8'] && function_exists('iconv') ? iconv($context['character_set'], 'UTF-8', $file['filename']) : (!$context['utf8'] && function_exists('mb_convert_encoding') ? mb_convert_encoding($file['filename'], 'UTF-8', $context['character_set']) : $file['filename']);
if (!empty($context['prepend_attachment_id']))
$utf8name = $_REQUEST['attach'] . ' - ' . $utf8name;
// On mobile devices, audio and video should be served inline so the browser can play them.
if (isset($_REQUEST['image']) || (isBrowser('is_mobile') && (strpos($file['mime_type'], 'audio/') !== 0 || strpos($file['mime_type'], 'video/') !== 0)))
$disposition = 'inline';
else
$disposition = 'attachment';
// Different browsers like different standards...
if (isBrowser('firefox'))
header('content-disposition: ' . $disposition . '; filename*=UTF-8\'\'' . rawurlencode(preg_replace_callback('~&#(\d{3,8});~', 'fixchar__callback', $utf8name)));
elseif (isBrowser('opera'))
header('content-disposition: ' . $disposition . '; filename="' . preg_replace_callback('~&#(\d{3,8});~', 'fixchar__callback', $utf8name) . '"');
elseif (isBrowser('ie'))
header('content-disposition: ' . $disposition . '; filename="' . urlencode(preg_replace_callback('~&#(\d{3,8});~', 'fixchar__callback', $utf8name)) . '"');
else
header('content-disposition: ' . $disposition . '; filename="' . $utf8name . '"');
// If this has an "image extension" - but isn't actually an image - then ensure it isn't cached cause of silly IE.
if (!isset($_REQUEST['image']) && in_array($file['fileext'], array('gif', 'jpg', 'bmp', 'png', 'jpeg', 'tiff')))
header('cache-control: no-cache');
else
header('cache-control: max-age=' . (525600 * 60) . ', private');
// Multipart and resuming support
if (isset($_SERVER['HTTP_RANGE']))
{
send_http_status(206);
header("content-length: $new_length");
header("content-range: bytes $range-$range_end/$file[size]");
}
else
header("content-length: " . $file['size']);
// Allow customizations to hook in here before we send anything to modify any headers needed. Or to change the process of how we output.
call_integration_hook('integrate_download_headers');
// Try to buy some time...
@set_time_limit(600);
// For multipart/resumable downloads, send the requested chunk(s) of the file
if (isset($_SERVER['HTTP_RANGE']))
{
while (@ob_get_level() > 0)
@ob_end_clean();
header_remove('content-encoding');
// 40 kilobytes is a good-ish amount
$chunksize = 40 * 1024;
$bytes_sent = 0;
$fp = fopen($file['filePath'], 'rb');
fseek($fp, $range);
while (!feof($fp) && (!connection_aborted()) && ($bytes_sent < $new_length))
{
$buffer = fread($fp, $chunksize);
echo($buffer);
flush();
$bytes_sent += strlen($buffer);
}
fclose($fp);
}
// Since we don't do output compression for files this large...
elseif ($file['size'] > 4194304)
{
// Forcibly end any output buffering going on.
while (@ob_get_level() > 0)
@ob_end_clean();
header_remove('content-encoding');
$fp = fopen($file['filePath'], 'rb');
while (!feof($fp))
{
echo fread($fp, 8192);
flush();
}
fclose($fp);
}
// On some of the less-bright hosts, readfile() is disabled. It's just a faster, more byte safe, version of what's in the if.
elseif (@readfile($file['filePath']) === null)
echo file_get_contents($file['filePath']);
die();
}
?>
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