/
spyder.py
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/
spyder.py
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import asyncio
from aioudp import UDPServer
from collections import namedtuple
from datetime import datetime
from random import SystemRandom
from bencode import bencode, bdecode, BTFailure
from utils import (generate_node_id, generate_id, get_routing_table_index, xor, decode_nodes, encode_nodes,
get_rand_bool, fetch_k_closest_nodes, decode_values, Node, decode_bkeys)
Searcher = namedtuple("searcher", ["info_hash", "nodes", "values", "attempts_count", "timestamp"])
class DHTSpyder(UDPServer):
def __init__(self, bootstrap_nodes, node_id=None, miner_interval=0.001, **kwargs):
super(DHTSpyder, self).__init__(**kwargs)
self.bootstrap_nodes = bootstrap_nodes
self.node_id = node_id or generate_node_id()
self.miner_interval = miner_interval
self.routing_table = [set() for _ in range(160)]
self.candidates = set()
self.searchers = {}
self.searchers_seq = 0
self.random = SystemRandom()
def connection_made(self):
# Bootstrap
for node in self.bootstrap_nodes:
self.find_node(node, self.node_id)
# Start miner
asyncio.ensure_future(self._dig_periodically(), loop=self.loop)
asyncio.ensure_future(self._update_searchers_periodically(), loop=self.loop)
async def datagram_received(self, data, addr):
try:
msg = bdecode(data, decoder=decode_bkeys)
except BTFailure:
# TODO: Log error
pass
else:
self.handle_message(msg, addr)
def _fetch_random_candidates(self, k):
result = self.random.sample(self.candidates, k)
for item in result:
self.candidates.remove(item)
return result
def _new_event(self, handler):
asyncio.ensure_future(handler, loop=self.loop)
async def _dig_periodically(self):
while True:
target_id = generate_node_id()
nodes = [
*self.get_closest_nodes(target_id),
*self._fetch_random_candidates(min(len(self.candidates), 7))
]
for _, host, port in nodes:
self.find_node((host, port), target_id)
await asyncio.sleep(self.miner_interval)
async def _update_searchers_periodically(self):
while True:
now = datetime.now()
for t, item in self.searchers.copy().items():
if (now - item.timestamp).seconds >= 120:
if item.values:
self._new_event(self.peers_values_received(item.info_hash, item.values))
self.searchers.pop(t)
await asyncio.sleep(1)
def send_message(self, data, addr):
self.send(bencode(data), addr)
def find_node(self, addr, target=None):
self.send_message({
"t": generate_id(),
"y": "q",
"q": "find_node",
"a": {
"id": generate_node_id(),
"target": target or generate_node_id()
}
}, addr)
def get_peers(self, addr, info_hash, t=None):
self.send_message({
"t": t or generate_id(),
"y": "q",
"q": "get_peers",
"a": {
"id": generate_node_id(),
"info_hash": info_hash
}
}, addr)
def get_closest_nodes(self, target_id, k_value=8):
closest_l = set()
closest_r = set()
r_table_idx = get_routing_table_index(xor(self.node_id, target_id))
idx = r_table_idx
while idx >= 0 and len(closest_l) < k_value:
closest_l |= set(fetch_k_closest_nodes(self.routing_table[idx], target_id, k_value))
idx -= 1
idx = r_table_idx + 1
while idx < 160 and len(closest_r) < k_value:
closest_r |= set(fetch_k_closest_nodes(self.routing_table[idx], target_id, k_value))
idx += 1
return fetch_k_closest_nodes(closest_l | closest_r, target_id, k_value)
def add_node(self, node):
r_table_index = get_routing_table_index(xor(node.id, self.node_id))
rt = self.routing_table[r_table_index]
if len(rt) < 1600:
rt.add(node)
elif get_rand_bool() and node not in rt:
rt.remove(self.random.sample(rt, 1)[0])
else:
self.find_node((node.host, node.port))
def search_peers(self, info_hash):
if self.searchers_seq >= 2 ** 32 - 1:
self.searchers_seq = 0
else:
self.searchers_seq += 1
t = self.searchers_seq.to_bytes(4, "big")
self.searchers[t] = Searcher(info_hash, set(), set(), 8, datetime.now())
for node in self.get_closest_nodes(info_hash, 16):
self.get_peers((node.host, node.port), info_hash, t)
def update_peers_searcher(self, t, nodes, values):
info_hash, old_nodes, old_values, attempts_count, timestamp = self.searchers.pop(t)
# "nodes" and "values" must be instance of "set" type
new_nodes = old_nodes | nodes
new_values = old_values | values
# If new_closest contains same data as old_closest, we decrease attempt counter
new_closest, old_closest = (set(fetch_k_closest_nodes(n, info_hash, 16)) for n in (new_nodes, old_nodes))
if new_closest == old_closest:
attempts_count -= 1
if attempts_count > 0:
self.searchers[t] = Searcher(info_hash, new_nodes, new_values, attempts_count, timestamp)
for node in new_closest:
self.get_peers((node.host, node.port), info_hash, t)
elif new_values:
self._new_event(self.peers_values_received(info_hash, new_values))
def handle_message(self, msg, addr):
try:
msg_type = str(msg.get("y", b""), "utf-8")
if msg_type == "r":
self.handle_response(msg, addr)
elif msg_type == "q":
self.handle_query(msg, addr)
except:
self.send_message({
"y": "e",
"e": [202, "Server Error"],
"t": msg.get("t", "")
}, addr)
raise
def handle_response(self, msg, addr):
args = msg["r"]
t = msg["t"]
node_id = args["id"]
nodes = set(decode_nodes(args.get("nodes", b"")))
values = set(decode_values(args.get("values", [])))
if t in self.searchers:
self.update_peers_searcher(t, nodes, values)
else:
new_candidates = self.random.sample(nodes, min(len(nodes), 8))
if len(self.candidates) > 160000:
self._fetch_random_candidates(len(self.candidates) - 160000)
self.candidates.update(new_candidates)
self.add_node(Node(node_id, addr[0], addr[1]))
def handle_query(self, msg, addr):
args = msg["a"]
node_id = args["id"]
query_type = str(msg["q"], "utf-8")
response_id = self.node_id
if query_type == "ping":
self.send_message({
"t": msg["t"],
"y": "r",
"r": {
"id": response_id
}
}, addr)
self._new_event(self.ping_received(node_id, addr))
elif query_type == "find_node":
target_node_id = args["target"]
self.send_message({
"t": msg["t"],
"y": "r",
"r": {
"id": response_id,
"nodes": encode_nodes(self.get_closest_nodes(target_node_id))
}
}, addr)
self._new_event(self.find_node_received(node_id, target_node_id, addr))
elif query_type == "get_peers":
info_hash = args["info_hash"]
token = generate_node_id()
self.send_message({
"t": msg["t"],
"y": "r",
"r": {
"id": response_id,
"nodes": encode_nodes(self.get_closest_nodes(info_hash)),
"token": token
}
}, addr)
self._new_event(self.get_peers_received(node_id, info_hash, addr))
elif query_type == "announce_peer":
info_hash = args["info_hash"]
port = args.get("port", None)
self.send_message({
"t": msg["t"],
"y": "r",
"r": {
"id": response_id
}
}, addr)
self._new_event(self.announce_peer_received(node_id, info_hash, port, addr))
self.add_node(Node(node_id, addr[0], addr[1]))
async def ping_received(self, node_id, addr):
pass
async def find_node_received(self, node_id, target, addr):
pass
async def get_peers_received(self, node_id, info_hash, addr):
pass
async def announce_peer_received(self, node_id, info_hash, port, addr):
pass
async def peers_values_received(self, info_hash, peers):
pass