I am trying to get the peer list from the trackers using https://wiki.theory.org/BitTorrent_Tracker_Protocol
But most of the torrent files available on the net use a udp tracker. The above website is for HTTP trackers. The torrent files with HTTP based trackers give an error.(Passkey error , or hash error or user error or 404 not found response)
Right now my request code for all HTTP trackers look like :
payload = urllib.urlencode(payload) for ann in self.torrent.announce_list: if("udp" not in ann[0]): url = ann[0] print "Encoded Request URL :",(url + "?" + payload) print "Requesting Tracker for Peer List" try: response = urllib.urlopen(url + "?" + payload).read() print "RESPONSE :",response except Exception, e: print e
I have crosschecked my request URL against the requests being made by uTorrent using wireshark. They all match. The info-hash is being generated correctly.
How do I retrieve the peer list from UDP as well as HTTP trackers ? I am trying not to use any external library like lib-torrent. Some guidance would be really helpful.
The following code worked for me. Calling announce_udp() with the tracker URL and the payload dictionary with all the URL parameeters.
import binascii, urllib, socket, random, struct from bcode import bdecode from urlparse import urlparse, urlunsplit def announce_udp(tracker,payload): tracker = tracker.lower() parsed = urlparse(tracker) # Teporarly Change udp:// to http:// to get hostname and portnumbe url = parsed.geturl()[3:] url = "http" + url hostname = urlparse(url).hostname port = urlparse(url).port sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM) sock.settimeout(8) conn = (socket.gethostbyname(hostname), port) #sock.bind((socket.gethostname(),s_port)) #Get connection ID req, transaction_id = udp_create_connection_request() sock.sendto(req, conn); buf = sock.recvfrom(2048)[0] connection_id = udp_parse_connection_response(buf, transaction_id) #Annoucing s_port = sock.getsockname()[1] #get port number to which socket is connected req, transaction_id = udp_create_announce_request(connection_id, payload,s_port) sock.sendto(req, conn) print "Announce Request Sent" buf = sock.recvfrom(2048)[0] print "Response received" return udp_parse_announce_response(buf, transaction_id) def udp_create_announce_request(connection_id, payload, s_port): action = 0x1 #action (1 = announce) transaction_id = udp_get_transaction_id() # print "2.Transaction ID :", transaction_id buf = struct.pack("!q", connection_id) #first 8 bytes is connection id buf += struct.pack("!i", action) #next 4 bytes is action buf += struct.pack("!i", transaction_id) #followed by 4 byte transaction id buf += struct.pack("!20s", urllib.unquote(payload['info_hash'])) #the info hash of the torrent we announce ourselves in buf += struct.pack("!20s", urllib.unquote(payload['peer_id'])) #the peer_id we announce buf += struct.pack("!q", int(urllib.unquote(payload['downloaded']))) #number of bytes downloaded buf += struct.pack("!q", int(urllib.unquote(payload['left']))) #number of bytes left buf += struct.pack("!q", int(urllib.unquote(payload['uploaded']))) #number of bytes uploaded buf += struct.pack("!i", 0x2) #event 2 denotes start of downloading buf += struct.pack("!i", 0x0) #IP address set to 0. Response received to the sender of this packet key = udp_get_transaction_id() #Unique key randomized by client buf += struct.pack("!i", key) buf += struct.pack("!i", -1) #Number of peers required. Set to -1 for default buf += struct.pack("!i", s_port) #port on which response will be sent return (buf, transaction_id) def udp_parse_announce_response(buf, sent_transaction_id): #print "Response is:"+str(buf) if len(buf) < 20: raise RuntimeError("Wrong response length while announcing: %s" % len(buf)) action = struct.unpack_from("!i", buf)[0] #first 4 bytes is action res_transaction_id = struct.unpack_from("!i", buf, 4)[0] #next 4 bytes is transaction id if res_transaction_id != sent_transaction_id: raise RuntimeError("Transaction ID doesnt match in announce response! Expected %s, got %s" % (sent_transaction_id, res_transaction_id)) print "Reading Response" if action == 0x1: print "Action is 3" ret = dict() offset = 8; #next 4 bytes after action is transaction_id, so data doesnt start till byte 8 ret['interval'] = struct.unpack_from("!i", buf, offset)[0] print "Interval:"+str(ret['interval']) offset += 4 ret['leeches'] = struct.unpack_from("!i", buf, offset)[0] print "Leeches:"+str(ret['leeches']) offset += 4 ret['seeds'] = struct.unpack_from("!i", buf, offset)[0] print "Seeds:"+str(ret['seeds']) offset += 4 peers = list() x = 0 while offset != len(buf): peers.append(dict()) peers[x]['IP'] = struct.unpack_from("!i",buf,offset)[0] print "IP: "+socket.inet_ntoa(struct.pack("!i",peers[x]['IP'])) offset += 4 if offset >= len(buf): raise RuntimeError("Error while reading peer port") peers[x]['port'] = struct.unpack_from("!H",buf,offset)[0] print "Port: "+str(peers[x]['port']) offset += 2 x += 1 return ret,peers else: #an error occured, try and extract the error string error = struct.unpack_from("!s", buf, 8) print "Action="+str(action) raise RuntimeError("Error while annoucing: %s" % error) def udp_create_connection_request(): connection_id = 0x41727101980 #default connection id action = 0x0 #action (0 = give me a new connection id) transaction_id = udp_get_transaction_id() print "1.Transaction ID :", transaction_id buf = struct.pack("!q", connection_id) #first 8 bytes is connection id buf += struct.pack("!i", action) #next 4 bytes is action buf += struct.pack("!i", transaction_id) #next 4 bytes is transaction id return (buf, transaction_id) def udp_parse_connection_response(buf, sent_transaction_id): if len(buf) < 16: raise RuntimeError("Wrong response length getting connection id: %s" % len(buf)) action = struct.unpack_from("!i", buf)[0] #first 4 bytes is action res_transaction_id = struct.unpack_from("!i", buf, 4)[0] #next 4 bytes is transaction id if res_transaction_id != sent_transaction_id: raise RuntimeError("Transaction ID doesnt match in connection response! Expected %s, got %s" % (sent_transaction_id, res_transaction_id)) if action == 0x0: connection_id = struct.unpack_from("!q", buf, 8)[0] #unpack 8 bytes from byte 8, should be the connection_id return connection_id elif action == 0x3: error = struct.unpack_from("!s", buf, 8) raise RuntimeError("Error while trying to get a connection response: %s" % error) pass def udp_get_transaction_id(): return int(random.randrange(0, 255))
