[wpmu-trac] [WordPress MU Trac] #1128: Byte-range file downloads (iPhone/iPod support)

[WordPress MU Trac]

#1128: Byte-range file downloads (iPhone/iPod support)
--------------------------+-------------------------------------------------
 Reporter:  cjgibbs       |       Owner:  somebody           
     Type:  enhancement   |      Status:  new                
 Priority:  normal        |   Milestone:                     
Component:  Optimisation  |     Version:                     
 Severity:  normal        |    Keywords:  byte-range download
--------------------------+-------------------------------------------------
 The problem:
 Audio/video files uploaded to wordpress mu blogs would not play on the
 iPhone/iPod touch because the WPMU file handler does not support byte-
 range downloading.

 The solution:
 Implement byte-range file serving for browsers/devices that support it.
 Remove the readfile() call at the bottom of wp-content/blogs.php
 Then add the following in it's place:

 {{{
 function wp_range_download($file) {

         $fp = @fopen($file, 'rb');

         $size   = filesize($file); // File size
         $length = $size;           // Content length
         $start  = 0;               // Start byte
         $end    = $size - 1;       // End byte
         // Now that we've gotten so far without errors we send the accept
 range header
         /* At the moment we only support single ranges.
          * Multiple ranges requires some more work to ensure it works
 correctly
          * and comply with the spesifications:
 http://www.w3.org/Protocols/rfc2616/rfc2616-sec19.html#sec19.2
          *
          * Multirange support annouces itself with:
          * header('Accept-Ranges: bytes');
          *
          * Multirange content must be sent with multipart/byteranges
 mediatype,
          * (mediatype = mimetype)
          * as well as a boundry header to indicate the various chunks of
 data.
          */
         header("Accept-Ranges: 0-$length");
         // header('Accept-Ranges: bytes');
         // multipart/byteranges
         // http://www.w3.org/Protocols/rfc2616/rfc2616-sec19.html#sec19.2
         if (isset($_SERVER['HTTP_RANGE'])) {

                 $c_start = $start;
                 $c_end   = $end;
                 // Extract the range string
                 list(, $range) = explode('=', $_SERVER['HTTP_RANGE'], 2);
                 // Make sure the client hasn't sent us a multibyte range
                 if (strpos($range, ',') !== false) {

                         // (?) Shoud this be issued here, or should the
 first
                         // range be used? Or should the header be ignored
 and
                         // we output the whole content?
                         header('HTTP/1.1 416 Requested Range Not
 Satisfiable');
                         header("Content-Range: bytes $start-$end/$size");
                         // (?) Echo some info to the client?
                         exit;
                 }
                 // If the range starts with an '-' we start from the
 beginning
                 // If not, we forward the file pointer
                 // And make sure to get the end byte if spesified
                 if ($range0 == '-') {

                         // The n-number of the last bytes is requested
                         $c_start = $size - substr($range, 1);
                 }
                 else {

                         $range  = explode('-', $range);
                         $c_start = $range[0];
                         $c_end   = (isset($range[1]) &&
 is_numeric($range[1])) ? $range[1] : $size;
                 }
                 /* Check the range and make sure it's treated according to
 the specs.
                  * http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html
                  */
                 // End bytes can not be larger than $end.
                 $c_end = ($c_end > $end) ? $end : $c_end;
                 // Validate the requested range and return an error if
 it's not correct.
                 if ($c_start > $c_end || $c_start > $size - 1 || $c_end >=
 $size) {

                         header('HTTP/1.1 416 Requested Range Not
 Satisfiable');
                         header("Content-Range: bytes $start-$end/$size");
                         // (?) Echo some info to the client?
                         exit;
                 }
                 $start  = $c_start;
                 $end    = $c_end;
                 $length = $end - $start + 1; // Calculate new content
 length
                 fseek($fp, $start);
                 header('HTTP/1.1 206 Partial Content');
         }
         // Notify the client the byte range we'll be outputting
         header("Content-Range: bytes $start-$end/$size");
         header("Content-Length: $length");

         // Start buffered download
         $buffer = 1024 * 8;
         while(!feof($fp) && ($p = ftell($fp)) <= $end) {

                 if ($p + $buffer > $end) {

                         // In case we're only outputtin a chunk, make sure
 we don't
                         // read past the length
                         $buffer = $end - $p + 1;
                 }
                 set_time_limit(0); // Reset time limit for big files
                 echo fread($fp, $buffer);
                 flush(); // Free up memory. Otherwise large files will
 trigger PHP's memory limit.
         }

         fclose($fp);

 }

 if (isset($_SERVER['HTTP_RANGE']))  {
         wp_range_download($file);
 } else {
         readfile( $file );
 }
 }}}

-- 
Ticket URL: <http://trac.mu.wordpress.org/ticket/1128>
WordPress MU Trac <http://mu.wordpress.org/>
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