Torrent BEncode

PHP Library for decoding and encoding BitTorrent BEncoded data.

What is BEncode?

Bencode (pronounced like B encode) is the encoding used by the peer-to-peer file sharing system BitTorrent for storing and transmitting loosely structured data.

It supports four different types of values:

• byte strings,
• integers,
• lists, and
• dictionaries (associative arrays).

Bencoding is most commonly used in torrent files. These metadata files are simply bencoded dictionaries.

While less efficient than a pure binary encoding, bencoding is simple and (because numbers are encoded as text in decimal notation) is unaffected by endianness, which is important for a cross-platform application like BitTorrent. It is also fairly flexible, as long as applications ignore unexpected dictionary keys, so that new ones can be added without creating incompatibilities.

Requirements

Apache or Nginx = Latest production version
PHP >= 5.3.0

Installation

Add this package in your composer.json and update composer.

{
	"require": {
		"bhutanio/torrent-bencode": "dev-master"
	}
}

Update Composer

composer update or php composer.phar update

Usage

With Composer

	
	require 'vendor/autoload.php';

	$bcoder = new Bhutanio\BEncode;
	$bcoder->set([
		'announce'=>'http://www.private-tracker.com',
		'comment'=>'Downloaded from Private Tracker',
		'created_by'=>'PrivateTracker v1.0'
	]);

	// decode Torrent file
	$torrent = $bcoder->bdecode( File::get('AwesomeMovie.torrent'));
	print_r($torrent);

	// show Torrent contents
	$files = $bcoder->filelist( $torrent );
	print_r($files);
	
	// make Torrent private
	$torrent = $bcoder->make_private($torrent);
	print_r($torrent);

	$infohash = sha1($bcoder->bencode($torrent["info"]));
	$binhash = pack("H*", $bcoder->bencode($torrent["info"])));

Without Composer

	require 'path/to/BEncode.php';

	// use above example

Functions

/**
 * Data Setter
 * @param array $data [array of public variables]
 * eg:
 *  $bcoder = new \Bhutanio\BEncode;
 * 	$bcoder->set([
 *		'announce'=>'http://www.example.com',
 *		'comment'=>'Downloaded from example.com',
 *		'created_by'=>'TorrentSite v1.0'
 *	]);
 */
public function set($data=array()) {}

/**
 * Decode a torrent file into Bencoded data
 * @param  string  $s 	[link to torrent file]
 * @param  integer $pos [file position pointer]
 * @return array/null 	[Array of Bencoded data]
 * eg:
 * 		$bcoder = new \Bhutanio\BEncode;
 * 		$torrent = $bcoder->bdecode( File::get('MyAwesomeTorrent.torrent'));
 *  	var_dump($torrent);
 */
public function bdecode($s, &$pos=0) {}

/**
 * Created Torrent file from Bencoded data
 * @param  array $d [array data of a decoded torrent file]
 * @return string 	[data can be downloaded as torrent]
 */
public function bencode(&$d) {}

/**
 * Decode a torrent file into Bencoded data
 * @param  string $filename 	[File Path]
 * @return array/null 			[Array of Bencoded data]
 */
public function bdecode_file($filename) {}

/**
 * Generate list of files in a torrent
 * @param  array $data 	[array data of a decoded torrent file]
 * @return array 		[list of files in an array]
 */
public function filelist($data) {}

/**
 * Replace array data on Decoded torrent data so that it can be bencoded into a private torrent file.
 * Provide the custom data using $this->set();
 * @param  array $data 	[array data of a decoded torrent file]
 * @return array 		[array data for torrent file]
 */
public function make_private($data) {}