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tracker.py
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tracker.py
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# File: tracker.py
# Author: <your name here>
# SID: <your student id here>
# Date: <the date when this file was last updated/created/edited>
# Description: this file contains the implementation of the tracker class.
import bencodepy
import socket
import threading
import uuid # to generate an ID
import time # for timestamp
class Tracker:
"""
This class contains methods that provide implementations to support trackerless peers
supporting the DHT and KRPC protocols
"""
DHT_PORT = 12001
def __init__(self, peer, server, torrent, announce=True):
"""
TODO: Add more work here as needed.
:param server:
:param torrent:
:param announce:
"""
self._peer = peer
self._server = server
self._torrent = torrent
self._is_announce = announce
# self._clienthandler = server.clienthandlers[0]
self.udp_socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
self.udp_socket.setsockopt(socket.SOL_SOCKET, socket.SO_BROADCAST, 1)
self.udp_socket.bind(("", self.DHT_PORT))
# will story a list of dictionaries representing entries in the routing table
# dictionaries stored here are in the following form
# {'nodeID': '<the node id is a SHA1 hash of the ip_address and port of the server node and a random uuid>',
# 'ip_address': '<the ip address of the node>', 'port': '<the port number of the node',
# 'info_hash': '<the info hash from the torrent file>', last_changed': 'timestamp'}
# self._routing_table = []
self.peers = []
def broadcast(self, message, self_broadcast_enabled=False):
try:
# print(f'Broadcast: {message}')
encoded_message = self.encode(message)
self.udp_socket.sendto(encoded_message, ('<broadcast>', self.DHT_PORT))
print(f'(T) Broadcasting --> {message}')
except socket.error as error:
print(f'(T) Error broadcasting on port ({self.DHT_PORT}) --> {err}')
def send_udp_message(self, message, ip, port):
try:
print(f'(T) sent UDP message --> {ip} | {port} | {message}')
new_socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
message = self.encode(message)
new_socket.sendto(message, (ip, port))
except Exception as err:
print(f'(T) Error sending UDP message --> {err}')
def broadcast_listener(self):
try:
print(f'(T) Listening at DHT port --> {self.DHT_PORT}')
while True:
raw_data, sender_ip_and_port = self.udp_socket.recvfrom(4096)
if raw_data:
data = self.decode(raw_data)
ip_sender = sender_ip_and_port[0]
port_sender = sender_ip_and_port[1]
print(f'(T) data recieved --> {ip_sender} | {port_sender} | {data}')
# print(f'data recieved by sender')
self.process_query(data, ip_sender, port_sender)
except Exception as err:
print(f"(T) Error listening at port ({self.DHT_PORT}) --> {err}")
#############################################################
def process_query(self, data, ip, port):
# make sure we arent talking to ourself
if str(data['id']) == str(self._peer.id):
print("(T) got message from myself")
return
# main logic
if data['type'] == 'query':
if data['action'] == 'ping':
is_new_peer = self.addPeer(data['id'])
# THIS IF STATEMENT WILL STOP YOU FROM QUERYING YOURSELF
if is_new_peer: # connect to its server
print('(T) Added a new Peer')
message = {
'type': 'response',
'action': 'ping',
'id': str(self._peer.id)
}
self.send_udp_message(message, ip, self.DHT_PORT)
elif data['action'] == 'info_hash':
# someone is asking for my info hash --> ok
my_info_hash = self._torrent.info_hash()
sender_info_hash = data['info_hash']
if my_info_hash == sender_info_hash: # I have the file they want
message = {
'type': 'response',
'action': 'info_hash',
'id': str(self._peer.id),
'res': 'yes',
'ip': self._peer._ip,
'port': self._server.port
}
else:
message = {
'type': 'response',
'action': 'info_hash',
'id': str(self._peer.id),
'res': 'no'
}
self.send_udp_message(message, ip, self.DHT_PORT)
elif data['type'] == 'response':
if data['action'] == 'ping':
is_new_peer = self.addPeer(data['id'])
# ask if they have file
info_hash = self._torrent.info_hash()
message = {
'type': 'query',
'action': 'info_hash',
'id': str(self._peer.id),
'info_hash': info_hash
}
self.send_udp_message(message, ip, self.DHT_PORT)
elif data['action'] == 'info_hash':
sender_id = data['id']
if data['res'] == 'yes':
print(f'(T) Peer: {sender_id} has the file')
# the peer with data['id'] has the file we want
# connect to its server using data['ip'] & data['port']
self._peer._connect_to_peer(data['port'], data['ip'], data['port'])
else:
print(f'(T) Peer: {sender_id} does not have the file ')
# dont worry about it for right now
#############################################################
def addPeer(self, new_peer_id):
# check to see if we have peer
for peer in self.peers:
if peer['id'] == new_peer_id:
print(f'(T) Peer already tracked --> id: {new_peer_id}')
return False
# we dont have peer
peer = {
'id': new_peer_id,
'ip': None,
'port': None,
'connected': False
}
self.peers.append(peer)
return True
def encode(self, message):
"""
bencodes a message
:param message: a dictionary representing the message
:return: the bencoded message
"""
return bencodepy.encode(message)
def decode(self, bencoded_message):
"""
Decodes a bencoded message
:param bencoded_message: the bencoded message
:return: the original message
"""
bc = bencodepy.Bencode(encoding='utf-8')
return bc.decode(bencoded_message)
def run(self, start_with_broadcast=True):
# start listening
threading.Thread(target=self.broadcast_listener).start()
me = {
'id': str(self._peer.id)
}
self.peers.append(me)
if start_with_broadcast:
# announce me
message = {
'type': 'query',
'action': 'ping',
'id': str(self._peer.id)
}
self.broadcast(message)