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<?php
// +----------------------------------------------------------------------+
// | Decode and Encode data in Bittorrent format |
// +----------------------------------------------------------------------+
// | Copyright (C) 2004-2005 Markus Tacker <m@tacker.org> |
// +----------------------------------------------------------------------+
// | This library is free software; you can redistribute it and/or |
// | modify it under the terms of the GNU Lesser General Public |
// | License as published by the Free Software Foundation; either |
// | version 2.1 of the License, or (at your option) any later version. |
// | |
// | This library is distributed in the hope that it will be useful, |
// | but WITHOUT ANY WARRANTY; without even the implied warranty of |
// | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
// | Lesser General Public License for more details. |
// | |
// | You should have received a copy of the GNU Lesser General Public |
// | License along with this library; if not, write to the |
// | Free Software Foundation, Inc. |
// | 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA |
// +----------------------------------------------------------------------+
/**
* Encode data in Bittorrent format
*
* Based on
* Original Python implementation by Petru Paler <petru@paler.net>
* PHP translation by Gerard Krijgsman <webmaster@animesuki.com>
* Gerard's regular expressions removed by Carl Ritson <critson@perlfu.co.uk>
* BEncoding is a simple, easy to implement method of associating
* data types with information in a file. The values in a torrent
* file are bEncoded.
* There are 4 different data types that can be bEncoded:
* Integers, Strings, Lists and Dictionaries.
* [http://www.monduna.com/bt/faq.html]
*
* @package File_Bittorrent2
* @category File
* @author Markus Tacker <m@tacker.org>
* @version $Id: Encode.php 97 2009-04-26 11:26:37Z m $
*/
/**
* Include required classes
*/
require_once 'PEAR.php';
require_once 'File/Bittorrent2/Exception.php';
/**
* Encode data in Bittorrent format
*
* Based on
* Original Python implementation by Petru Paler <petru@paler.net>
* PHP translation by Gerard Krijgsman <webmaster@animesuki.com>
* Gerard's regular expressions removed by Carl Ritson <critson@perlfu.co.uk>
* BEncoding is a simple, easy to implement method of associating
* data types with information in a file. The values in a torrent
* file are bEncoded.
* There are 4 different data types that can be bEncoded:
* Integers, Strings, Lists and Dictionaries.
* [http://www.monduna.com/bt/faq.html]
*
* @package File_Bittorrent2
* @category File
* @author Markus Tacker <m@tacker.org>
*/
class File_Bittorrent2_Encode
{
/**
* Encode a var in BEncode format
*
* @param mixed Variable to encode
* @return string
* @throws File_Bittorrent2_Exception if unsupported type should be encoded
*/
function encode($mixed)
{
switch (gettype($mixed)) {
case is_null($mixed):
return $this->encode_string('');
case 'string':
return $this->encode_string($mixed);
case 'integer':
case 'double':
return $this->encode_int(sprintf('%.0f', round($mixed)));
case 'array':
return $this->encode_array($mixed);
default:
throw new File_Bittorrent2_Exception('Unsupported type. Variable must be one of \'string\', \'integer\', \'double\' or \'array\'', File_Bittorrent2_Exception::encode);
}
}
/**
* BEncodes a string
*
* Strings are prefixed with their length followed by a colon.
* For example, "Monduna" would bEncode to 7:Monduna and "BitTorrents"
* would bEncode to 11:BitTorrents.
*
* @param string
* @return string
*/
function encode_string($str)
{
return strlen($str) . ':' . $str;
}
/**
* BEncodes a integer
*
* Integers are prefixed with an i and terminated by an e. For
* example, 123 would bEcode to i123e, -3272002 would bEncode to
* i-3272002e.
*
* @param int
* @return string
*/
function encode_int($int)
{
return 'i' . $int . 'e';
}
/**
* BEncodes an array
* This code assumes arrays with purely integer indexes are lists,
* arrays which use string indexes assumed to be dictionaries.
*
* Dictionaries are prefixed with a d and terminated by an e. They
* are similar to list, except that items are in key value pairs. The
* dictionary {"key":"value", "Monduna":"com", "bit":"Torrents", "number":7}
* would bEncode to d3:key5:value7:Monduna3:com3:bit:8:Torrents6:numberi7ee
*
* Lists are prefixed with a l and terminated by an e. The list
* should contain a series of bEncoded elements. For example, the
* list of strings ["Monduna", "Bit", "Torrents"] would bEncode to
* l7:Monduna3:Bit8:Torrentse. The list [1, "Monduna", 3, ["Sub", "List"]]
* would bEncode to li1e7:Mondunai3el3:Sub4:Listee
*
* @param array
* @return string
*/
function encode_array(array $array)
{
// Check for strings in the keys
$isList = true;
foreach (array_keys($array) as $key) {
if (!is_int($key)) {
$isList = false;
break;
}
}
if ($isList) {
// Wie build a list
ksort($array, SORT_NUMERIC);
$return = 'l';
foreach ($array as $val) {
$return .= $this->encode($val);
}
$return .= 'e';
} else {
// We build a Dictionary
ksort($array, SORT_STRING);
$return = 'd';
foreach ($array as $key => $val) {
$return .= $this->encode(strval($key));
$return .= $this->encode($val);
}
$return .= 'e';
}
return $return;
}
}
?>