mirror of
https://github.com/WhatCD/Gazelle.git
synced 2024-12-15 03:46:25 +00:00
322 lines
9.5 KiB
PHP
322 lines
9.5 KiB
PHP
<?
|
|
/*******************************************************************************
|
|
|~~~~ Gazelle bencode parser ~~~~|
|
|
--------------------------------------------------------------------------------
|
|
|
|
Welcome to the Gazelle bencode parser. bencoding is the way of encoding data
|
|
that bittorrent uses in torrent files. When we read the torrent files, we get
|
|
one long string that must be parsed into a format we can easily edit - that's
|
|
where this file comes into play.
|
|
|
|
There are 4 data types in bencode:
|
|
* String
|
|
* Int
|
|
* List - array without keys
|
|
- like array('value', 'value 2', 'value 3', 'etc')
|
|
* Dictionary - array with string keys
|
|
- like array['key 1'] = 'value 1'; array['key 2'] = 'value 2';
|
|
|
|
Before you go any further, we recommend reading the sections on bencoding and
|
|
metainfo file structure here: http://wiki.theory.org/BitTorrentSpecification
|
|
|
|
//----- How we store the data -----//
|
|
|
|
* Strings
|
|
- Stored as php strings. Not difficult to remember.
|
|
|
|
* Integers
|
|
- Stored as php strings with an [*INT*] marker
|
|
- Can be stored an an int on 64 bit boxes for uber speed (we do this)
|
|
- If stored as an int on 32 bit boxes, it won't allow for any size over 2 gigs
|
|
|
|
* Lists
|
|
- Stored as a BENCODE_LIST object.
|
|
- The actual list is in BENCODE_LIST::$Val, as an array with incrementing integer indices
|
|
- The list in BENCODE_LIST::$Val is populated by the BENCODE_LIST::dec() function
|
|
|
|
* Dictionaries
|
|
- Stored as a BENCODE_DICT object.
|
|
- The actual list is in BENCODE_DICT::$Val, as an array with incrementing integer indices
|
|
- The list in BENCODE_DICT::$Val is populated by the BENCODE_DICT::dec() function
|
|
|
|
//----- BENCODE_* Objects -----//
|
|
|
|
Lists and dictionaries are stored as objects. They each have the following
|
|
functions:
|
|
|
|
* decode(Type, $Key)
|
|
- Decodes ANY bencoded element, given the type and the key
|
|
- Gets the position and string from $this
|
|
|
|
* encode($Val)
|
|
- Encodes ANY non-bencoded element, given the value
|
|
|
|
* dec()
|
|
- Decodes either a dictionary or a list, depending on where it's called from
|
|
- Uses the decode() function quite a bit
|
|
|
|
* enc()
|
|
- Encodes either a dictionary or a list, depending on where it's called from
|
|
- Relies mostly on the encode() function
|
|
|
|
Finally, as all torrents are just large dictionaries, the TORRENT class extends
|
|
the BENCODE_DICT class.
|
|
|
|
|
|
|
|
**Note** The version we run doesn't store ints as strings marked with [*INT*]
|
|
We store them as php integers. You can do this too for added speed and reduced
|
|
hackery, if you're running a 64 bit box, or if you're running a 32 bit box and
|
|
don't care about files larger than 2 gigs. The system with the [*INT*]s was
|
|
coded up in around 4 minutes for STC when we discovered this problem, then
|
|
discovered that floats aren't accurate enough to use. :(
|
|
|
|
*******************************************************************************/
|
|
class BENCODE2 {
|
|
var $Val; // Decoded array
|
|
var $Pos = 1; // Pointer that indicates our position in the string
|
|
var $Str = ''; // Torrent string
|
|
|
|
function __construct($Val, $IsParsed = false) {
|
|
if (!$IsParsed) {
|
|
$this->Str = $Val;
|
|
$this->dec();
|
|
} else {
|
|
$this->Val = $Val;
|
|
}
|
|
}
|
|
|
|
// Decode an element based on the type
|
|
function decode($Type, $Key) {
|
|
if (ctype_digit($Type)) { // Element is a string
|
|
// Get length of string
|
|
$StrLen = $Type;
|
|
while ($this->Str[$this->Pos + 1] != ':') {
|
|
$this->Pos++;
|
|
$StrLen.=$this->Str[$this->Pos];
|
|
}
|
|
$this->Val[$Key] = substr($this->Str, $this->Pos + 2, $StrLen);
|
|
|
|
$this->Pos += $StrLen;
|
|
$this->Pos += 2;
|
|
|
|
} elseif ($Type == 'i') { // Element is an int
|
|
$this->Pos++;
|
|
|
|
// Find end of integer (first occurance of 'e' after position)
|
|
$End = strpos($this->Str, 'e', $this->Pos);
|
|
|
|
// Get the integer, and mark it as an int (on our version 64 bit box, we cast it to an int)
|
|
$this->Val[$Key] = '[*INT*]'.substr($this->Str, $this->Pos, $End-$this->Pos);
|
|
$this->Pos = $End + 1;
|
|
|
|
} elseif ($Type == 'l') { // Element is a list
|
|
$this->Val[$Key] = new BENCODE_LIST(substr($this->Str, $this->Pos));
|
|
$this->Pos += $this->Val[$Key]->Pos;
|
|
|
|
} elseif ($Type == 'd') { // Element is a dictionary
|
|
$this->Val[$Key] = new BENCODE_DICT(substr($this->Str, $this->Pos));
|
|
$this->Pos += $this->Val[$Key]->Pos;
|
|
// Sort by key to respect spec
|
|
ksort($this->Val[$Key]->Val);
|
|
|
|
} else {
|
|
die('Invalid torrent file');
|
|
}
|
|
}
|
|
|
|
function encode($Val) {
|
|
if (is_string($Val)) {
|
|
if (substr($Val, 0, 7) == '[*INT*]') {
|
|
return 'i'.substr($Val,7).'e';
|
|
} else {
|
|
return strlen($Val).':'.$Val;
|
|
}
|
|
} elseif (is_object($Val)) {
|
|
return $Val->enc();
|
|
} else {
|
|
return 'fail';
|
|
}
|
|
}
|
|
}
|
|
|
|
class BENCODE_LIST extends BENCODE2 {
|
|
function enc() {
|
|
$Str = 'l';
|
|
reset($this->Val);
|
|
while (list($Key, $Value) = each($this->Val)) {
|
|
$Str.=$this->encode($Value);
|
|
}
|
|
return $Str.'e';
|
|
}
|
|
|
|
// Decode a list
|
|
function dec() {
|
|
$Key = 0; // Array index
|
|
$Length = strlen($this->Str);
|
|
while ($this->Pos<$Length) {
|
|
$Type = $this->Str[$this->Pos];
|
|
// $Type now indicates what type of element we're dealing with
|
|
// It's either an integer (string), 'i' (an integer), 'l' (a list), 'd' (a dictionary), or 'e' (end of dictionary/list)
|
|
|
|
if ($Type == 'e') { // End of list
|
|
$this->Pos += 1;
|
|
unset($this->Str); // Since we're finished parsing the string, we don't need to store it anymore. Benchmarked - this makes the parser run way faster.
|
|
return;
|
|
}
|
|
|
|
// Decode the bencoded element.
|
|
// This function changes $this->Pos and $this->Val, so you don't have to.
|
|
$this->decode($Type, $Key);
|
|
++ $Key;
|
|
}
|
|
return true;
|
|
}
|
|
}
|
|
|
|
class BENCODE_DICT extends BENCODE2 {
|
|
function enc() {
|
|
$Str = 'd';
|
|
reset($this->Val);
|
|
while (list($Key, $Value) = each($this->Val)) {
|
|
$Str.=strlen($Key).':'.$Key.$this->encode($Value);
|
|
}
|
|
return $Str.'e';
|
|
}
|
|
|
|
// Decode a dictionary
|
|
function dec() {
|
|
$Length = strlen($this->Str);
|
|
while ($this->Pos < $Length) {
|
|
|
|
if ($this->Str[$this->Pos] == 'e') { // End of dictionary
|
|
$this->Pos += 1;
|
|
unset($this->Str); // Since we're finished parsing the string, we don't need to store it anymore. Benchmarked - this makes the parser run way faster.
|
|
return;
|
|
}
|
|
|
|
// Get the dictionary key
|
|
// Length of the key, in bytes
|
|
$KeyLen = $this->Str[$this->Pos];
|
|
|
|
// Allow for multi-digit lengths
|
|
while ($this->Str[$this->Pos + 1] != ':' && $this->Pos + 1 < $Length) {
|
|
$this->Pos++;
|
|
$KeyLen.=$this->Str[$this->Pos];
|
|
}
|
|
// $this->Pos is now on the last letter of the key length
|
|
// Adding 2 brings it past that character and the ':' to the beginning of the string
|
|
$this->Pos+=2;
|
|
|
|
// Get the name of the key
|
|
$Key = substr($this->Str, $this->Pos, $KeyLen);
|
|
|
|
// Move the position past the key to the beginning of the element
|
|
$this->Pos += $KeyLen;
|
|
$Type = $this->Str[$this->Pos];
|
|
// $Type now indicates what type of element we're dealing with
|
|
// It's either an integer (string), 'i' (an integer), 'l' (a list), 'd' (a dictionary), or 'e' (end of dictionary/list)
|
|
|
|
// Decode the bencoded element.
|
|
// This function changes $this->Pos and $this->Val, so you don't have to.
|
|
$this->decode($Type, $Key);
|
|
|
|
|
|
}
|
|
return true;
|
|
}
|
|
}
|
|
|
|
|
|
class TORRENT extends BENCODE_DICT {
|
|
function dump() {
|
|
// Convenience function used for testing and figuring out how we store the data
|
|
print_r($this->Val);
|
|
}
|
|
|
|
function dump_data() {
|
|
// Function which serializes $this->Val for storage
|
|
return base64_encode(serialize($this->Val));
|
|
}
|
|
|
|
function set_announce_url($Announce) {
|
|
$this->Val['announce'] = $Announce;
|
|
ksort($this->Val);
|
|
}
|
|
|
|
// Returns an array of:
|
|
// * the files in the torrent
|
|
// * the total size of files described therein
|
|
function file_list() {
|
|
$FileList = array();
|
|
if (!isset($this->Val['info']->Val['files'])) { // Single file mode
|
|
$TotalSize = substr($this->Val['info']->Val['length'],7);
|
|
$FileList[] = array($TotalSize, $this->get_name());
|
|
} else { // Multiple file mode
|
|
$FileNames = array();
|
|
$FileSizes = array();
|
|
$TotalSize = 0;
|
|
$Files = $this->Val['info']->Val['files']->Val;
|
|
if (isset($Files[0]->Val['path.utf-8'])) {
|
|
$PathKey = 'path.utf-8';
|
|
} else {
|
|
$PathKey = 'path';
|
|
}
|
|
foreach ($Files as $File) {
|
|
$FileSize = substr($File->Val['length'], 7);
|
|
$TotalSize += $FileSize;
|
|
|
|
$FileName = ltrim(implode('/', $File->Val[$PathKey]->Val), '/');
|
|
$FileSizes[] = $FileSize;
|
|
$FileNames[] = $FileName;
|
|
}
|
|
natcasesort($FileNames);
|
|
foreach ($FileNames as $Index => $FileName) {
|
|
$FileList[] = array($FileSizes[$Index], $FileName);
|
|
}
|
|
}
|
|
return array($TotalSize, $FileList);
|
|
}
|
|
|
|
function get_name() {
|
|
if (isset($this->Val['info']->Val['name.utf-8'])) {
|
|
return $this->Val['info']->Val['name.utf-8'];
|
|
} else {
|
|
return $this->Val['info']->Val['name'];
|
|
}
|
|
}
|
|
|
|
function make_private() {
|
|
//----- The following properties do not affect the infohash:
|
|
|
|
// anounce-list is an unofficial extension to the protocol
|
|
// that allows for multiple trackers per torrent
|
|
unset($this->Val['announce-list']);
|
|
|
|
// Bitcomet & Azureus cache peers in here
|
|
unset($this->Val['nodes']);
|
|
|
|
// Azureus stores the dht_backup_enable flag here
|
|
unset($this->Val['azureus_properties']);
|
|
|
|
// Remove web-seeds
|
|
unset($this->Val['url-list']);
|
|
|
|
// Remove libtorrent resume info
|
|
unset($this->Val['libtorrent_resume']);
|
|
|
|
//----- End properties that do not affect the infohash
|
|
|
|
if (!empty($this->Val['info']->Val['private']) && $this->Val['info']->Val['private'] == '[*INT*]1') {
|
|
return true;
|
|
} else {
|
|
// Torrent is not private!
|
|
// add private tracker flag and sort info dictionary
|
|
$this->Val['info']->Val['private'] = '[*INT*]1';
|
|
ksort($this->Val['info']->Val);
|
|
return false;
|
|
}
|
|
}
|
|
}
|
|
?>
|