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MDL-25314 improved prevention of output buffering + detection of misconfigured servers

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Scripts that do not want buffered output just define NO_OUTPUT_BUFFERING before including config.php.
The fileserving code now checks if the headers are already sent which detects misconfigured servers.
This commit is contained in:
Petr Skoda
2010-11-19 03:40:43 +00:00
parent 6e4453f5f8
commit cbad562eee
18 changed files with 279 additions and 255 deletions
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lib/filelib.php
+120 -92
View File
@@ -1474,11 +1474,43 @@ function send_file_not_found() {
print_error('filenotfound', 'error', $CFG->wwwroot.'/course/view.php?id='.$COURSE->id); //this is not displayed on IIS??
}
/**
* Check output buffering settings before sending file
* @private to be called only from lib/filelib.php !
* @return void
*/
function prepare_file_sending() {
$olddebug = error_reporting(0);
// IE compatibility HACK - it does not like zlib compression much
// there is also a problem with the length header in older PHP versions
if (ini_get_bool('zlib.output_compression')) {
ini_set('zlib.output_compression', 'Off');
}
// flush and close all buffers if possible
while(ob_get_level()) {
if (!ob_end_flush()) {
// prevent infinite loop when buffer can not be closed
break;
}
}
error_reporting($olddebug);
// now make sure we can actually send out headers,
// if not it is a fatal problem because we could
// create XSS problems through student files
// or the content of the file would be borked.
if (headers_sent()) {
throw new file_serving_exception('Headers already sent, can not serve file!');
}
}
/**
* Handles the sending of temporary file to user, download is forced.
* File is deleted after abort or successful sending.
*
* @global object
* @param string $path path to file, preferably from moodledata/temp/something; or content of file itself
* @param string $filename proposed file name when saving file
* @param bool $path is content of file
@@ -1499,32 +1531,31 @@ function send_temp_file($path, $filename, $pathisstring=false) {
@register_shutdown_function('send_temp_file_finished', $path);
}
//IE compatibility HACK!
if (ini_get('zlib.output_compression')) {
ini_set('zlib.output_compression', 'Off');
}
// if user is using IE, urlencode the filename so that multibyte file name will show up correctly on popup
if (check_browser_version('MSIE')) {
$filename = urlencode($filename);
}
//flush the buffers - save memory and disable sid rewrite
// this also disables zlib compression
prepare_file_sending();
$filesize = $pathisstring ? strlen($path) : filesize($path);
@header('Content-Disposition: attachment; filename='.$filename);
@header('Content-Length: '.$filesize);
header('Content-Disposition: attachment; filename='.$filename);
header('Content-Length: '.$filesize);
if (strpos($CFG->wwwroot, 'https://') === 0) { //https sites - watch out for IE! KB812935 and KB316431
@header('Cache-Control: max-age=10');
@header('Expires: '. gmdate('D, d M Y H:i:s', 0) .' GMT');
@header('Pragma: ');
header('Cache-Control: max-age=10');
header('Expires: '. gmdate('D, d M Y H:i:s', 0) .' GMT');
header('Pragma: ');
} else { //normal http - prevent caching at all cost
@header('Cache-Control: private, must-revalidate, pre-check=0, post-check=0, max-age=0');
@header('Expires: '. gmdate('D, d M Y H:i:s', 0) .' GMT');
@header('Pragma: no-cache');
header('Cache-Control: private, must-revalidate, pre-check=0, post-check=0, max-age=0');
header('Expires: '. gmdate('D, d M Y H:i:s', 0) .' GMT');
header('Pragma: no-cache');
}
@header('Accept-Ranges: none'); // Do not allow byteserving
header('Accept-Ranges: none'); // Do not allow byteserving
while (@ob_end_flush()); //flush the buffers - save memory and disable sid rewrite
// send the contents
if ($pathisstring) {
echo $path;
} else {
@@ -1609,17 +1640,15 @@ function send_file($path, $filename, $lifetime = 'default' , $filter=0, $pathiss
}
*/
//IE compatibiltiy HACK!
if (ini_get('zlib.output_compression')) {
ini_set('zlib.output_compression', 'Off');
}
//try to disable automatic sid rewrite in cookieless mode
@ini_set("session.use_trans_sid", "false");
//flush the buffers - save memory and disable sid rewrite
//this also disables zlib compression
prepare_file_sending();
//do not put '@' before the next header to detect incorrect moodle configurations,
//error should be better than "weird" empty lines for admins/users
//TODO: should we remove all those @ before the header()? Are all of the values supported on all servers?
header('Last-Modified: '. gmdate('D, d M Y H:i:s', $lastmodified) .' GMT');
// if user is using IE, urlencode the filename so that multibyte file name will show up correctly on popup
@@ -1628,19 +1657,19 @@ function send_file($path, $filename, $lifetime = 'default' , $filter=0, $pathiss
}
if ($forcedownload) {
@header('Content-Disposition: attachment; filename="'.$filename.'"');
header('Content-Disposition: attachment; filename="'.$filename.'"');
} else {
@header('Content-Disposition: inline; filename="'.$filename.'"');
header('Content-Disposition: inline; filename="'.$filename.'"');
}
if ($lifetime > 0) {
@header('Cache-Control: max-age='.$lifetime);
@header('Expires: '. gmdate('D, d M Y H:i:s', time() + $lifetime) .' GMT');
@header('Pragma: ');
header('Cache-Control: max-age='.$lifetime);
header('Expires: '. gmdate('D, d M Y H:i:s', time() + $lifetime) .' GMT');
header('Pragma: ');
if (empty($CFG->disablebyteserving) && !$pathisstring && $mimetype != 'text/plain' && $mimetype != 'text/html') {
@header('Accept-Ranges: bytes');
header('Accept-Ranges: bytes');
if (!empty($_SERVER['HTTP_RANGE']) && strpos($_SERVER['HTTP_RANGE'],'bytes=') !== FALSE) {
// byteserving stuff - for acrobat reader and download accelerators
@@ -1676,41 +1705,43 @@ function send_file($path, $filename, $lifetime = 'default' , $filter=0, $pathiss
}
} else {
/// Do not byteserve (disabled, strings, text and html files).
@header('Accept-Ranges: none');
header('Accept-Ranges: none');
}
} else { // Do not cache files in proxies and browsers
if (strpos($CFG->wwwroot, 'https://') === 0) { //https sites - watch out for IE! KB812935 and KB316431
@header('Cache-Control: max-age=10');
@header('Expires: '. gmdate('D, d M Y H:i:s', 0) .' GMT');
@header('Pragma: ');
header('Cache-Control: max-age=10');
header('Expires: '. gmdate('D, d M Y H:i:s', 0) .' GMT');
header('Pragma: ');
} else { //normal http - prevent caching at all cost
@header('Cache-Control: private, must-revalidate, pre-check=0, post-check=0, max-age=0');
@header('Expires: '. gmdate('D, d M Y H:i:s', 0) .' GMT');
@header('Pragma: no-cache');
header('Cache-Control: private, must-revalidate, pre-check=0, post-check=0, max-age=0');
header('Expires: '. gmdate('D, d M Y H:i:s', 0) .' GMT');
header('Pragma: no-cache');
}
@header('Accept-Ranges: none'); // Do not allow byteserving when caching disabled
header('Accept-Ranges: none'); // Do not allow byteserving when caching disabled
}
if (empty($filter)) {
if ($mimetype == 'text/html' && !empty($CFG->usesid)) {
//cookieless mode - rewrite links
@header('Content-Type: text/html');
header('Content-Type: text/html');
$path = $pathisstring ? $path : implode('', file($path));
$path = sid_ob_rewrite($path);
$filesize = strlen($path);
$pathisstring = true;
} else if ($mimetype == 'text/plain') {
@header('Content-Type: Text/plain; charset=utf-8'); //add encoding
header('Content-Type: Text/plain; charset=utf-8'); //add encoding
} else {
@header('Content-Type: '.$mimetype);
header('Content-Type: '.$mimetype);
}
@header('Content-Length: '.$filesize);
while (@ob_end_flush()); //flush the buffers - save memory and disable sid rewrite
header('Content-Length: '.$filesize);
// send the contents
if ($pathisstring) {
echo $path;
} else {
@readfile($path);
}
} else { // Try to put the file through filters
if ($mimetype == 'text/html') {
$options = new stdClass();
@@ -1725,9 +1756,9 @@ function send_file($path, $filename, $lifetime = 'default' , $filter=0, $pathiss
$output = sid_ob_rewrite($output);
}
@header('Content-Length: '.strlen($output));
@header('Content-Type: text/html');
while (@ob_end_flush()); //flush the buffers - save memory and disable sid rewrite
header('Content-Length: '.strlen($output));
header('Content-Type: text/html');
// send the contents
echo $output;
// only filter text if filter all files is selected
} else if (($mimetype == 'text/plain') and ($filter == 1)) {
@@ -1741,14 +1772,14 @@ function send_file($path, $filename, $lifetime = 'default' , $filter=0, $pathiss
$output = sid_ob_rewrite($output);
}
@header('Content-Length: '.strlen($output));
@header('Content-Type: text/html; charset=utf-8'); //add encoding
while (@ob_end_flush()); //flush the buffers - save memory and disable sid rewrite
header('Content-Length: '.strlen($output));
header('Content-Type: text/html; charset=utf-8'); //add encoding
// send the contents
echo $output;
} else { // Just send it out raw
@header('Content-Length: '.$filesize);
@header('Content-Type: '.$mimetype);
while (@ob_end_flush()); //flush the buffers - save memory and disable sid rewrite
header('Content-Length: '.$filesize);
header('Content-Type: '.$mimetype);
// send the contents
if ($pathisstring) {
echo $path;
}else {
@@ -1808,14 +1839,13 @@ function send_stored_file($stored_file, $lifetime=86400 , $filter=0, $forcedownl
$lastmodified = $stored_file->get_timemodified();
$filesize = $stored_file->get_filesize();
//IE compatibiltiy HACK!
if (ini_get('zlib.output_compression')) {
ini_set('zlib.output_compression', 'Off');
}
//try to disable automatic sid rewrite in cookieless mode
@ini_set("session.use_trans_sid", "false");
//flush the buffers - save memory and disable sid rewrite
//this also disables zlib compression
prepare_file_sending();
//do not put '@' before the next header to detect incorrect moodle configurations,
//error should be better than "weird" empty lines for admins/users
//TODO: should we remove all those @ before the header()? Are all of the values supported on all servers?
@@ -1827,19 +1857,19 @@ function send_stored_file($stored_file, $lifetime=86400 , $filter=0, $forcedownl
}
if ($forcedownload) {
@header('Content-Disposition: attachment; filename="'.$filename.'"');
header('Content-Disposition: attachment; filename="'.$filename.'"');
} else {
@header('Content-Disposition: inline; filename="'.$filename.'"');
header('Content-Disposition: inline; filename="'.$filename.'"');
}
if ($lifetime > 0) {
@header('Cache-Control: max-age='.$lifetime);
@header('Expires: '. gmdate('D, d M Y H:i:s', time() + $lifetime) .' GMT');
@header('Pragma: ');
header('Cache-Control: max-age='.$lifetime);
header('Expires: '. gmdate('D, d M Y H:i:s', time() + $lifetime) .' GMT');
header('Pragma: ');
if (empty($CFG->disablebyteserving) && $mimetype != 'text/plain' && $mimetype != 'text/html') {
@header('Accept-Ranges: bytes');
header('Accept-Ranges: bytes');
if (!empty($_SERVER['HTTP_RANGE']) && strpos($_SERVER['HTTP_RANGE'],'bytes=') !== FALSE) {
// byteserving stuff - for acrobat reader and download accelerators
@@ -1874,37 +1904,37 @@ function send_stored_file($stored_file, $lifetime=86400 , $filter=0, $forcedownl
}
} else {
/// Do not byteserve (disabled, strings, text and html files).
@header('Accept-Ranges: none');
header('Accept-Ranges: none');
}
} else { // Do not cache files in proxies and browsers
if (strpos($CFG->wwwroot, 'https://') === 0) { //https sites - watch out for IE! KB812935 and KB316431
@header('Cache-Control: max-age=10');
@header('Expires: '. gmdate('D, d M Y H:i:s', 0) .' GMT');
@header('Pragma: ');
header('Cache-Control: max-age=10');
header('Expires: '. gmdate('D, d M Y H:i:s', 0) .' GMT');
header('Pragma: ');
} else { //normal http - prevent caching at all cost
@header('Cache-Control: private, must-revalidate, pre-check=0, post-check=0, max-age=0');
@header('Expires: '. gmdate('D, d M Y H:i:s', 0) .' GMT');
@header('Pragma: no-cache');
header('Cache-Control: private, must-revalidate, pre-check=0, post-check=0, max-age=0');
header('Expires: '. gmdate('D, d M Y H:i:s', 0) .' GMT');
header('Pragma: no-cache');
}
@header('Accept-Ranges: none'); // Do not allow byteserving when caching disabled
header('Accept-Ranges: none'); // Do not allow byteserving when caching disabled
}
if (empty($filter)) {
$filtered = false;
if ($mimetype == 'text/html' && !empty($CFG->usesid)) {
//cookieless mode - rewrite links
@header('Content-Type: text/html');
header('Content-Type: text/html');
$text = $stored_file->get_content();
$text = sid_ob_rewrite($text);
$filesize = strlen($text);
$filtered = true;
} else if ($mimetype == 'text/plain') {
@header('Content-Type: Text/plain; charset=utf-8'); //add encoding
header('Content-Type: Text/plain; charset=utf-8'); //add encoding
} else {
@header('Content-Type: '.$mimetype);
header('Content-Type: '.$mimetype);
}
@header('Content-Length: '.$filesize);
while (@ob_end_flush()); //flush the buffers - save memory and disable sid rewrite
header('Content-Length: '.$filesize);
// send the contents
if ($filtered) {
echo $text;
} else {
@@ -1924,9 +1954,9 @@ function send_stored_file($stored_file, $lifetime=86400 , $filter=0, $forcedownl
$output = sid_ob_rewrite($output);
}
@header('Content-Length: '.strlen($output));
@header('Content-Type: text/html');
while (@ob_end_flush()); //flush the buffers - save memory and disable sid rewrite
header('Content-Length: '.strlen($output));
header('Content-Type: text/html');
// send the contents
echo $output;
// only filter text if filter all files is selected
} else if (($mimetype == 'text/plain') and ($filter == 1)) {
@@ -1940,14 +1970,14 @@ function send_stored_file($stored_file, $lifetime=86400 , $filter=0, $forcedownl
$output = sid_ob_rewrite($output);
}
@header('Content-Length: '.strlen($output));
@header('Content-Type: text/html; charset=utf-8'); //add encoding
while (@ob_end_flush()); //flush the buffers - save memory and disable sid rewrite
header('Content-Length: '.strlen($output));
header('Content-Type: text/html; charset=utf-8'); //add encoding
// send the contents
echo $output;
} else { // Just send it out raw
@header('Content-Length: '.$filesize);
@header('Content-Type: '.$mimetype);
while (@ob_end_flush()); //flush the buffers - save memory and disable sid rewrite
header('Content-Length: '.$filesize);
header('Content-Type: '.$mimetype);
// send the contents
$stored_file->readfile();
}
}
@@ -2134,11 +2164,10 @@ function byteserving_send_file($handle, $mimetype, $ranges, $filesize) {
}
if (count($ranges) == 1) { //only one range requested
$length = $ranges[0][2] - $ranges[0][1] + 1;
@header('HTTP/1.1 206 Partial content');
@header('Content-Length: '.$length);
@header('Content-Range: bytes '.$ranges[0][1].'-'.$ranges[0][2].'/'.$filesize);
@header('Content-Type: '.$mimetype);
while (@ob_end_flush()); //flush the buffers - save memory and disable sid rewrite
header('HTTP/1.1 206 Partial content');
header('Content-Length: '.$length);
header('Content-Range: bytes '.$ranges[0][1].'-'.$ranges[0][2].'/'.$filesize);
header('Content-Type: '.$mimetype);
$buffer = '';
fseek($handle, $ranges[0][1]);
while (!feof($handle) && $length > 0) {
@@ -2156,11 +2185,10 @@ function byteserving_send_file($handle, $mimetype, $ranges, $filesize) {
$totallength += strlen($range[0]) + $range[2] - $range[1] + 1;
}
$totallength += strlen("\r\n--".BYTESERVING_BOUNDARY."--\r\n");
@header('HTTP/1.1 206 Partial content');
@header('Content-Length: '.$totallength);
@header('Content-Type: multipart/byteranges; boundary='.BYTESERVING_BOUNDARY);
header('HTTP/1.1 206 Partial content');
header('Content-Length: '.$totallength);
header('Content-Type: multipart/byteranges; boundary='.BYTESERVING_BOUNDARY);
//TODO: check if "multipart/x-byteranges" is more compatible with current readers/browsers/servers
while (@ob_end_flush()); //flush the buffers - save memory and disable sid rewrite
foreach($ranges as $range) {
$length = $range[2] - $range[1] + 1;
echo $range[0];