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- <?php
- /*
- * Bitstorm - A small and fast Bittorrent tracker
- * Copyright 2008 Peter Caprioli & Simon Sessingø
- *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, either version 3 of the License, or
- * (at your option) any later version.
- *
- * This program 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 General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program. If not, see <http://www.gnu.org/licenses/>.
- */
-
- /*************************
- ** Configuration start **
- *************************/
-
- /*
- * Enable debugging?
- * This allows anyone to see the entire peer database by appending ?debug to the announce URL.
- * It will also create debugging file used to report php errors.
- */
- define('__DEBUGGING_ENABLED', true);
-
- /**
- * Version
- */
- define('__VERSION', 1.5);
-
- /**
- * How often should clients pull server for new clients? (Seconds)
- */
- define('__INTERVAL', 1800);
-
- /**
- * What's the minimum interval a client may pull the server? (Seconds)
- * Some bittorrent clients does not obey this
- */
- define('__INTERVAL_MIN', 300);
-
- /**
- * How long should we wait for a client to re-announce after the last announce expires? (Seconds)
- */
- define('__CLIENT_TIMEOUT', 60);
-
- /**
- * Skip sending the peer id if client does not want it?
- * Hint: Should be set to true
- */
- define('__NO_PEER_ID', true);
-
- /**
- * Should seeders not see each others?
- * Hint: Should be set to true
- */
- define('__NO_SEED_P2P', true);
-
- /**
- * Where should we save the peer database
- * On Linux, you should use /dev/shm as it is very fast.
- * On Windows, you will need to change this value to some other valid path such as C:/Peers.txt
- */
- define('__LOCATION_PEERS', 'peers.txt');
-
- /**
- * Should we enable short announces?
- * This allows NATed clients to get updates much faster, but it also
- * takes more load on the server. (This is just an experimental feature which may be turned off)
- */
- define('__ENABLE_SHORT_ANNOUNCE', false);
-
- /**
- * In case someone tries to access the tracker using a browser, redirect to this URL or file
- */
- define('__REDIR_BROWSER', '');
-
- define('__LOG_FILE', __DIR__ . '/error.log');
-
- /***********************
- ** Configuration end **
- ***********************/
-
- if(__DEBUGGING_ENABLED === true) {
-
- set_error_handler(function ($errno, $errstr, $errfile, $errline) {
-
- if (file_exists(__LOG_FILE) === false) {
- $handle = fopen(__LOG_FILE, 'w+b');
- fclose($handle);
- }
-
- file_put_contents(__LOG_FILE, sprintf('Line: %s - Error: %s', $errline, $errstr));
-
- }, E_ALL);
-
- }
-
- //Send response as text
- header('Content-type: Text/Plain');
- header('X-Tracker-Version: Bitstorm ' . __VERSION); //Please give me some credit
-
- /**
- * If you *really* dont want to, comment this line out.
- * Bencoding function, returns a bencoded dictionary.
- * You may go ahead and enter custom keys in the dictionary in this function if you'd like.
- */
-
- function track($list, $interval = 60, $min_ival = 0)
- {
- if (is_string($list)) { //Did we get a string? Return an error to the client
- return 'd14:failure reason' . strlen($list) . ':' . $list . 'e';
- }
-
- $p = ''; //Peer directory
- $c = $i = 0; //Complete and Incomplete clients
-
- foreach ($list as $d) { //Runs for each client
- if ($d[7]) { //Are we seeding?
- $c++; //Seeding, add to complete list
- if (__NO_SEED_P2P && is_seed()) { //Seeds should not see each others
- continue;
- }
- } else {
- $i++; //Not seeding, add to incomplete list
- }
-
- //Do some bencoding
- $pid = '';
-
- if (isset($_GET['no_peer_id']) === false && __NO_PEER_ID) { //Shall we include the peer id
- $pid = '7:peer id' . strlen($d[1]) . ':' . $d[1];
- }
-
- $p .= 'd2:ip' . strlen($d[0]) . ':' . $d[0] . $pid . '4:porti' . $d[2] . 'ee';
- }
-
- //Add some other paramters in the dictionary and merge with peer list
- $r = 'd8:intervali' . $interval . 'e12:min intervali' . $min_ival . 'e8:completei' . $c . 'e10:incompletei' . $i . 'e5:peersl' . $p . 'ee';
-
- return $r;
- }
-
- //Find out if we are seeding or not. Assume not if unknown.
- function is_seed()
- {
- return (isset($_GET['left']) && (int)$_GET['left'] === 0);
- }
-
- /*
- * Yeah, this is the database engine. It's pretty bad, uses files to store peers.
- * Should be easy to rewrite to use SQL instead.
- *
- * Yes, sometimes collisions may occur and screw the DB over. It might or might not
- * recover by itself.
- */
-
- //Save database to file
- function db_save($data)
- {
- $b = serialize($data);
- $handle = fopen(__LOCATION_PEERS, 'wb');
-
- if ($handle === false) {
- return false;
- }
-
- if (flock($handle, LOCK_EX) === false) {
- return false;
- }
-
- fwrite($handle, $b);
- fclose($handle);
-
- return true;
- }
-
- //Load database from file
- function db_open()
- {
- $p = '';
- $handle = fopen(__LOCATION_PEERS, 'rb');
- if ($handle === false) {
- return false;
- }
-
- if (flock($handle, LOCK_EX) === false) {
- return false;
- }
-
- while (feof($handle) === false) {
- $p .= fread($handle, 512);
- }
-
- fclose($handle);
-
- return ((string)$p !== '') ? unserialize($p) : true;
- }
-
- //Check if DB file exists, otherwise create it
- function db_exists($createEmpty = false)
- {
- if (file_exists(__LOCATION_PEERS) === true) {
- return true;
- }
-
- if ($createEmpty === true) {
- return db_save([]);
- }
-
- return false;
- }
-
- //Default announce time
- $interval = __INTERVAL;
-
- //Minimal announce time (does not apply to short announces)
- $interval_min = __INTERVAL_MIN;
-
- /*
- * This is a pretty smart feature not present in other tracker software.
- * If you expect to have many NATed clients, add short as a GET parameter,
- * and clients will pull much more often.
- *
- * This can be done automatically, simply try to open a TCP connection to
- * the client and assume it is NATed if not successful.
- */
- if (isset($_GET['short']) && __ENABLE_SHORT_ANNOUNCE) {
- $interval = 120;
- $interval_min = 30;
- }
-
- //Did we get any parameters at all?
- //Client is probably a web browser, do a redirect
- if (empty($_GET)) {
- header('Location: ' . __REDIR_BROWSER);
- die();
- }
-
- //Create database if it does not exist
- db_exists(true) or die(track('Unable to create database'));
- $d = db_open();
-
- //Do we want to debug? (Should not be used by default)
- if (isset($_GET['debug']) && __DEBUGGING_ENABLED) {
- echo 'Connected peers:' . count($d) . "\n\n";
- die();
- }
-
- //Did we get a failure from the database?
- if ($d === false) {
- die(track('Database failure'));
- }
-
- //Do some input validation
- function valdata($g, $must_be_20_chars = false)
- {
- if (!isset($_GET[$g])) {
- die(track('Missing one or more arguments'));
- }
- if (!is_string($_GET[$g])) {
- die(track('Invalid types on one or more arguments'));
- }
- if ($must_be_20_chars && strlen($_GET[$g]) != 20) {
- die(track('Invalid length on ' . $g . ' argument'));
- }
- if (strlen($_GET[$g]) > 128) { //128 chars should really be enough
- die(track('Argument ' . $g . ' is too large to handle'));
- }
- }
-
- //Inputs that are needed, do not continue without these
- valdata('peer_id', true);
- valdata('port');
- valdata('info_hash', true);
-
- //Use the tracker key extension. Makes it much harder to steal a session.
- if (!isset($_GET['key'])) {
- $_GET['key'] = '';
- }
- valdata('key');
-
- //Do we have a valid client port?
- if (!ctype_digit($_GET['port']) || $_GET['port'] < 1 || $_GET['port'] > 65535) {
- die(track('Invalid client port'));
- }
-
- //Array key, unique for each client and torrent
- $sum = sha1($_GET['peer_id'] . $_GET['info_hash']);
-
- //Make sure we've got a user agent to avoid errors
- //Used for debugging
- if (!isset($_SERVER['HTTP_USER_AGENT'])) {
- $_SERVER['HTTP_USER_AGENT'] = ''; //Must always be set
- }
-
- //When should we remove the client?
- $expire = time() + $interval;
-
- //Have this client registered itself before? Check that it uses the same key
- if (isset($d[$sum])) {
- if ((string)$d[$sum][6] !== (string)$_GET['key']) {
- sleep(3); //Anti brute force
- die(track('Access denied, authentication failed'));
- }
- }
-
- //Add/update the client in our global list of clients, with some information
- $d[$sum] = [$_SERVER['REMOTE_ADDR'], $_GET['peer_id'], $_GET['port'], $expire, $_GET['info_hash'], $_SERVER['HTTP_USER_AGENT'], $_GET['key'], is_seed()];
-
- //No point in saving the user agent, unless we are debugging
- if (!__DEBUGGING_ENABLED) {
- unset($d[$sum][5]);
- } elseif (!empty($_GET)) { //We are debugging, add GET parameters to database
- $d[$sum]['get_parm'] = $_GET;
- }
-
- //Did the client stop the torrent?
- //We dont care about other events
- if (isset($_GET['event']) && (string)$_GET['event'] === 'stopped') {
- unset($d[$sum]);
- db_save($d);
- die(track([])); //The RFC says its OK to return whatever we want when the client stops downloading,
- //however, some clients will complain about the tracker not working, hence we return
- //an empty bencoded peer list
- }
-
- //Check if any client timed out
- foreach ($d as $k => $data) {
- if (time() > $data[3] + __CLIENT_TIMEOUT) { //Give the client some extra time before timeout
- unset($d[$k]); //Client has gone away, remove it
- }
- }
-
- //Save the client list
- db_save($d);
-
- //Compare info_hash to the rest of our clients and remove anyone who does not have the correct torrent
- foreach ($d as $id => $info) {
- if ((string)$info[4] !== (string)$_GET['info_hash']) {
- unset($d[$id]);
- }
- }
-
- // Remove self from list, no point in having ourselfes in the client dictionary
- unset($d[$sum]);
-
- // Add a few more seconds on the timeout to balance the load
- $interval += mt_rand(0, 10);
-
- // Bencode the dictionary and send it back
- echo track($d, $interval, $interval_min);
- exit(0);
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