W-Shadow.com

A .torrent file contains assorted metadata that is stored in a “bencoded dictionary” format. Bencoding is a relatively simple cross-platform encoding used by BitTorrent and a dictionary is basically an associative array. You can find a high-level overview of the file structure here.

To open or edit a .torrent file in PHP you can either parse it manually or use one of the wrapper classes available on the web. I recommend the Torrent RW class (local mirror) because it has the best feature set compared to other wrappers that I tested. Below you will find a short overview of the class and a few example scripts that demonstrate how you can analyze .torrent files and create new torrents using this wrapper.

Pros

• Simple class interface for all important metadata.
• Parse and edit existing torrent files or build new torrent files from scratch.
• Request torrent statistics from tracker(s).
• Good inline documentation.

Cons

Note : these apply to the current version and bugs may be fixed in future releases.

• When encoding the torrent to a string, tries to ksort() an object. This can trigger a warning message whenever outputting or saving a torrent file. Note that I’ve fixed this bug in the “local mirror” version, above.
• allow_url_fopen must be enabled to get stats from trackers. This is generally considered bad practice security-wise.
• The script requires PHP 5. This is not a major problem, just worth knowing if you want to incorporate TorrentRW in your own scripts and distribute them.

Examples

require_once 'Torrent.php';
 
/***********************
    Get torrent info
***********************/
$torrent = new Torrent( './test.torrent' );
echo "<pre>\nPrivate: ", $torrent->is_private() ? 'yes' : 'no', 
    "\nAnnounce: ", $torrent->announce(), 
    "\nName: ", $torrent->name(), 
    "\nComment: ", $torrent->comment(), 
    "\nPiece_length: ", $torrent->piece_length(), 
    "\nSize: ", $torrent->size( 2 ),
    "\nHash info: ", $torrent->hash_info(),
    "\nStats: ";
    var_dump( $torrent->scrape() );
    echo "\nContents: ";
    var_dump( $torrent->content() );
    //echo "\nSource data: ",  $torrent;
 
/***********************
    Create a new torrent
***********************/
$torrent = new Torrent( array( 'test.mp3', 'test.jpg' ), 'http://torrent.tracker/announce' );
//Send it to the browser 
$torrent->send();
//Alternatively, you can also save it as a new file
file_put_contents('new.torrent', (string) $torrent);