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))