udptscraper.php

<?php
	/* 	Torrent UDP Scraper
		v1.2
		
		2010 by Johannes Zinnau
		johannes@johnimedia.de
		
		Licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported License
		http://creativecommons.org/licenses/by-sa/3.0/
		
		It would be very nice if you send me your changes on this class, so that i can include them if they are improve it.
		Thanks!
		
		Usage:
		try{
			$timeout = 2;
			
			$scraper = new udptscraper($timeout);
			$ret = $scraper->scrape('udp://tracker.tld:port',array('0000000000000000000000000000000000000000'));
			
			print_r($ret);
		}catch(ScraperException $e){
			echo('Error: ' . $e->getMessage() . "<br />\n");
			echo('Connection error: ' . ($e->isConnectionError() ? 'yes' : 'no') . "<br />\n");
		}
	*/
	
	require_once(dirname(__FILE__) . '/tscraper.php');
	
	class udptscraper extends tscraper{
		
		/* 	$url: Tracker url like: udp://tracker.tld:port or udp://tracker.tld:port/announce
			$infohash: Infohash string or array (max 74 items). 40 char long infohash. 
			*/
		public function scrape($url,$infohash){
			if(!is_array($infohash)){ $infohash = array($infohash); }
			foreach($infohash as $hash){
				if(!preg_match('#^[a-f0-9]{40}$#i',$hash)){ throw new ScraperException('Invalid infohash: ' . $hash . '.'); }
			}
			if(count($infohash) > 74){ throw new ScraperException('Too many infohashes provided.'); }
			if(!preg_match('%udp://([^:/]*)(?::([0-9]*))?(?:/)?%si', $url, $m)){ throw new ScraperException('Invalid tracker url.'); }
			$tracker = 'udp://' . $m[1];
			$port = isset($m[2]) ? $m[2] : 80;
			
			$transaction_id = mt_rand(0,65535);
			$fp = fsockopen($tracker, $port, $errno, $errstr);
			if(!$fp){ throw new ScraperException('Could not open UDP connection: ' . $errno . ' - ' . $errstr,0,true); }
			stream_set_timeout($fp, $this->timeout);
			
			$current_connid = "\x00\x00\x04\x17\x27\x10\x19\x80";
			
			//Connection request
			$packet = $current_connid . pack("N", 0) . pack("N", $transaction_id);
			fwrite($fp,$packet);
			
			//Connection response
			$ret = fread($fp, 16);
			if(strlen($ret) < 1){ throw new ScraperException('No connection response.',0,true); }
			if(strlen($ret) < 16){ throw new ScraperException('Too short connection response.'); }
			$retd = unpack("Naction/Ntransid",$ret);
			if($retd['action'] != 0 || $retd['transid'] != $transaction_id){
				throw new ScraperException('Invalid connection response.');
			}
			$current_connid = substr($ret,8,8);
			
			//Scrape request
			$hashes = '';
			foreach($infohash as $hash){ $hashes .= pack('H*', $hash); }
			$packet = $current_connid . pack("N", 2) . pack("N", $transaction_id) . $hashes;
			fwrite($fp,$packet);
			
			//Scrape response
			$readlength = 8 + (12 * count($infohash));
			$ret = fread($fp, $readlength);
			if(strlen($ret) < 1){ throw new ScraperException('No scrape response.',0,true); }
			if(strlen($ret) < 8){ throw new ScraperException('Too short scrape response.'); }
			$retd = unpack("Naction/Ntransid",$ret);
			// Todo check for error string if response = 3
			if($retd['action'] != 2 || $retd['transid'] != $transaction_id){
				throw new ScraperException('Invalid scrape response.');
			}
			if(strlen($ret) < $readlength){ throw new ScraperException('Too short scrape response.'); }
			$torrents = array();
			$index = 8;
			foreach($infohash as $hash){
				$retd = unpack("Nseeders/Ncompleted/Nleechers",substr($ret,$index,12));
				$retd['infohash'] = $hash;
				$torrents[$hash] = $retd;
				$index = $index + 12;
			}
			
			return($torrents);
		}
	}
?>