Deliver Files With PHP

Deliver Files With PHP
Thomas Weinert

About me
 Application Developer
▹ PHP
▹ XSLT/XPath
▹ (some) Javascript

papaya CMS
▹ PHP based Content Management System
▹ uses XSLT for Templates

Thomas Weinert, papaya Software GmbH

Steps
 Block  Send
 Check ▹ At Once
▹ Filename ▹ Piece By Piece
▹ File ▹ Limit

Tell 
Optimize
▹ Date ▹ Traffic
▹ Size ▹ Performance
▹ Type ▹ Flash
▹ Name

Problems

Block
 Move outside document root


.htaccess
▹ Deny From All

Rewrite?


Check Filename
 dirname(), basename()
 preg_match

strrpos() + substr()


against database
▹ Use hashed random strings for id
▹ Split at chars
▹ virtual directory structure

Check File
 file_exists()
▹ return true for directories

is_file()

is_readable()


Check File Type
 getimagesize() (no GD needed)
 /usr/bin/file

ext/fileinfo (PHP 5.3)


Tell Date
 Last change

header('Last-modified: '.
gmdate('D, d M Y H:i:s', $fileDate.' GMT');


Valid until

header('Expires: '.
gmdate('D, d M Y H:i:s', $expireTime).' GMT');


Tell Size
 Size
▹ Show progress in browser

header('Content-length: '.$fileSize);


Tell Type
 File Mime Type

header('Content-type: '.$mimeType);


Rewrite Filenames
▹ IE check filename


Force Download
 IE and Opera

header('Content-type: application/octetstream');


Others

header('Content-type: application/octet-stream');


Tell Filename
 For files in browser or IE

header('Content-disposition: inline; filename=quot;'.
$data['file_name'].'quot;');


For downloads - except IE

header('Content-disposition: attachment; filename=quot;'.
$data['file_name'].'quot;');

 Escape “ and in filename with

Send – At Once
 fpassthru()
 readfile()


Pro:
▹ Easy

Contra:
▹ Less control


Send - Piece By Piece
 fread()
 fseek()

echo, print()

flush()


Send – Piece By Piece
<?php
if ($fh = fopen($localFileName, 'r')) {
while (!feof($fh) &&
connection_status() == 0) {
echo fread($fh, $bytesPerStep);
flush();
}
fclose($fh);
}
?>


Send – Piece By Piece
<?php
if ($fh = fopen($localFileName, 'r')) {
//seek file to start position
if ($fileOffset > 0) {
fseek($fh, $fileOffset);
}
while (!feof($fh) &&
connection_status() == 0) {
echo fread($fh, $bytesPerStep);
flush();
}
fclose($fh);
}
?> Weinert, papaya Software GmbH
Thomas

Optimize - Traffic
 Range-Header
▹ Send:
▪ header('Accept-Ranges: bytes');
▹ Receive:
▪ $_SERVER['HTTP_RANGE']
▪ bytes=[start1][]-[stop1][,start2][-][stop2][...]:
▹ Send:
▪ header('Accept-Ranges: bytes');
▪ header('HTTP/1.1 206 Partial Content');
▪ header(sprintf('Content-Range: bytes %d-%d/
%d', ...);

Send – Bandwidth Limit
 Track time and send bytes
 Sleep some time if sent to fast
▹ usleep(), sleep()

Send first bytes without limit


Why?
▹ Video-Streaming
▹ User don't need all data

if ($shapeRequest) {
$bytesSend += $bytesPerStep;
if ($bytesSend > $shapeLimitStart) {
$timeDiff = microtime(TRUE) - $timeStart;
$rate = ($bytesSend - $shapeLimitStart)
/ $timeDiff;

if ($rate > $shapeLimitRate) {
$sleepFunction($sleepTime);
}
}
}


Optimize - Performance
 Close Sessions
▹ session_write_close()

 X-Sendfile
▹ header('X-Sendfile: '.$localFileName);

▹ Header for Lighttpd
▹ Apache Extension


Optimize – Flash I
 Byte offset tables in video file
▹ ffmpeg ... -g 500 ...

Special player sends GET parameter
▹ JW FLV Player

Server checks GET parameter
▹ PHP script
▹ Lighttpd module


Optimize – Flash – Meta Data


Optimize – Flash II
 Check for GET parameters
▹ start, pos, position

Output magic bytes
▹ $flashHeader = 'FLV'.pack('CCNN', 1, 5, 9, 0);

▹ 01 (version) 05 (audio and video)
00 00 00 09 (header size)
00 00 00 00 (size of previous tag)

Seek file

Output file

Problems
 will disable flush() / cause buffering
▹ ob_start()
▹ session.use_trans_sid
▹ zlib.output_compression

▹ http:/www.php.net/flush (Comments)


Adobe Acrobat Reader in IE has buggy Range
headers support

Links
 X-Sendfile
▹ http://blog.lighttpd.net/articles/2006/07/02/x-
sendfile
▹ http://tn123.ath.cx/mod_xsendfile/


Flash
▹ http://www.jeroenwijering.com/
▹ http://ffmpeg.mplayerhq.hu/
▹

http://www.abasketfulofpapayas.de/

Deliver Files With PHP

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