505 lines
19 KiB
Python
505 lines
19 KiB
Python
# Copyright (c) 2017-2018, Neil Booth
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#
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# All rights reserved.
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#
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# See the file "LICENCE" for information about the copyright
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# and warranty status of this software.
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"""Peer management."""
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import asyncio
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import random
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import socket
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import ssl
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import time
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from asyncio import Event, sleep
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from collections import defaultdict, Counter
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from torba.tasks import TaskGroup
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from torba.rpc import (
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Connector, RPCSession, SOCKSProxy, Notification, handler_invocation,
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SOCKSError, RPCError
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)
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from torba.server.peer import Peer
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from torba.server.util import class_logger, protocol_tuple
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PEER_GOOD, PEER_STALE, PEER_NEVER, PEER_BAD = range(4)
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STALE_SECS = 24 * 3600
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WAKEUP_SECS = 300
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class BadPeerError(Exception):
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pass
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def assert_good(message, result, instance):
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if not isinstance(result, instance):
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raise BadPeerError(f'{message} returned bad result type '
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f'{type(result).__name__}')
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class PeerSession(RPCSession):
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"""An outgoing session to a peer."""
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async def handle_request(self, request):
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# We subscribe so might be unlucky enough to get a notification...
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if (isinstance(request, Notification) and
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request.method == 'blockchain.headers.subscribe'):
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pass
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else:
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await handler_invocation(None, request) # Raises
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class PeerManager:
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"""Looks after the DB of peer network servers.
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Attempts to maintain a connection with up to 8 peers.
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Issues a 'peers.subscribe' RPC to them and tells them our data.
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"""
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def __init__(self, env, db):
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self.logger = class_logger(__name__, self.__class__.__name__)
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# Initialise the Peer class
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Peer.DEFAULT_PORTS = env.coin.PEER_DEFAULT_PORTS
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self.env = env
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self.db = db
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# Our clearnet and Tor Peers, if any
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sclass = env.coin.SESSIONCLS
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self.myselves = [Peer(ident.host, sclass.server_features(env), 'env')
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for ident in env.identities]
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self.server_version_args = sclass.server_version_args()
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# Peers have one entry per hostname. Once connected, the
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# ip_addr property is either None, an onion peer, or the
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# IP address that was connected to. Adding a peer will evict
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# any other peers with the same host name or IP address.
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self.peers = set()
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self.permit_onion_peer_time = time.time()
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self.proxy = None
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self.group = TaskGroup()
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def _my_clearnet_peer(self):
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"""Returns the clearnet peer representing this server, if any."""
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clearnet = [peer for peer in self.myselves if not peer.is_tor]
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return clearnet[0] if clearnet else None
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def _set_peer_statuses(self):
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"""Set peer statuses."""
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cutoff = time.time() - STALE_SECS
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for peer in self.peers:
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if peer.bad:
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peer.status = PEER_BAD
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elif peer.last_good > cutoff:
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peer.status = PEER_GOOD
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elif peer.last_good:
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peer.status = PEER_STALE
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else:
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peer.status = PEER_NEVER
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def _features_to_register(self, peer, remote_peers):
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"""If we should register ourselves to the remote peer, which has
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reported the given list of known peers, return the clearnet
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identity features to register, otherwise None.
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"""
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# Announce ourself if not present. Don't if disabled, we
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# are a non-public IP address, or to ourselves.
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if not self.env.peer_announce or peer in self.myselves:
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return None
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my = self._my_clearnet_peer()
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if not my or not my.is_public:
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return None
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# Register if no matches, or ports have changed
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for peer in my.matches(remote_peers):
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if peer.tcp_port == my.tcp_port and peer.ssl_port == my.ssl_port:
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return None
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return my.features
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def _permit_new_onion_peer(self):
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"""Accept a new onion peer only once per random time interval."""
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now = time.time()
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if now < self.permit_onion_peer_time:
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return False
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self.permit_onion_peer_time = now + random.randrange(0, 1200)
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return True
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async def _import_peers(self):
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"""Import hard-coded peers from a file or the coin defaults."""
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imported_peers = self.myselves.copy()
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# Add the hard-coded ones unless only reporting ourself
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if self.env.peer_discovery != self.env.PD_SELF:
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imported_peers.extend(Peer.from_real_name(real_name, 'coins.py')
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for real_name in self.env.coin.PEERS)
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await self._note_peers(imported_peers, limit=None)
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async def _detect_proxy(self):
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"""Detect a proxy if we don't have one and some time has passed since
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the last attempt.
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If found self.proxy is set to a SOCKSProxy instance, otherwise
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None.
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"""
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host = self.env.tor_proxy_host
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if self.env.tor_proxy_port is None:
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ports = [9050, 9150, 1080]
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else:
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ports = [self.env.tor_proxy_port]
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while True:
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self.logger.info(f'trying to detect proxy on "{host}" '
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f'ports {ports}')
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proxy = await SOCKSProxy.auto_detect_host(host, ports, None)
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if proxy:
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self.proxy = proxy
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self.logger.info(f'detected {proxy}')
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return
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self.logger.info('no proxy detected, will try later')
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await sleep(900)
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async def _note_peers(self, peers, limit=2, check_ports=False,
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source=None):
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"""Add a limited number of peers that are not already present."""
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new_peers = []
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for peer in peers:
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if not peer.is_public or (peer.is_tor and not self.proxy):
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continue
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matches = peer.matches(self.peers)
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if not matches:
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new_peers.append(peer)
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elif check_ports:
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for match in matches:
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if match.check_ports(peer):
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self.logger.info(f'ports changed for {peer}')
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match.retry_event.set()
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if new_peers:
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source = source or new_peers[0].source
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if limit:
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random.shuffle(new_peers)
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use_peers = new_peers[:limit]
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else:
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use_peers = new_peers
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for peer in use_peers:
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self.logger.info(f'accepted new peer {peer} from {source}')
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peer.retry_event = Event()
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self.peers.add(peer)
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await self.group.add(self._monitor_peer(peer))
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async def _monitor_peer(self, peer):
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# Stop monitoring if we were dropped (a duplicate peer)
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while peer in self.peers:
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if await self._should_drop_peer(peer):
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self.peers.discard(peer)
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break
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# Figure out how long to sleep before retrying. Retry a
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# good connection when it is about to turn stale, otherwise
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# exponentially back off retries.
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if peer.try_count == 0:
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pause = STALE_SECS - WAKEUP_SECS * 2
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else:
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pause = WAKEUP_SECS * 2 ** peer.try_count
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pending, done = await asyncio.wait([peer.retry_event.wait()], timeout=pause)
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if done:
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peer.retry_event.clear()
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async def _should_drop_peer(self, peer):
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peer.try_count += 1
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is_good = False
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for kind, port in peer.connection_port_pairs():
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peer.last_try = time.time()
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kwargs = {}
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if kind == 'SSL':
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kwargs['ssl'] = ssl.SSLContext(ssl.PROTOCOL_TLS)
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host = self.env.cs_host(for_rpc=False)
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if isinstance(host, list):
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host = host[0]
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if self.env.force_proxy or peer.is_tor:
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if not self.proxy:
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return
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kwargs['proxy'] = self.proxy
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kwargs['resolve'] = not peer.is_tor
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elif host:
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# Use our listening Host/IP for outgoing non-proxy
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# connections so our peers see the correct source.
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kwargs['local_addr'] = (host, None)
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peer_text = f'[{peer}:{port} {kind}]'
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try:
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async with Connector(PeerSession, peer.host, port,
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**kwargs) as session:
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await asyncio.wait_for(
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self._verify_peer(session, peer),
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120 if peer.is_tor else 30
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)
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is_good = True
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break
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except BadPeerError as e:
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self.logger.error(f'{peer_text} marking bad: ({e})')
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peer.mark_bad()
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break
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except RPCError as e:
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self.logger.error(f'{peer_text} RPC error: {e.message} '
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f'({e.code})')
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except (OSError, SOCKSError, ConnectionError, asyncio.TimeoutError) as e:
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self.logger.info(f'{peer_text} {e}')
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if is_good:
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now = time.time()
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elapsed = now - peer.last_try
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self.logger.info(f'{peer_text} verified in {elapsed:.1f}s')
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peer.try_count = 0
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peer.last_good = now
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peer.source = 'peer'
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# At most 2 matches if we're a host name, potentially
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# several if we're an IP address (several instances
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# can share a NAT).
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matches = peer.matches(self.peers)
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for match in matches:
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if match.ip_address:
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if len(matches) > 1:
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self.peers.remove(match)
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# Force the peer's monitoring task to exit
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match.retry_event.set()
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elif peer.host in match.features['hosts']:
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match.update_features_from_peer(peer)
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else:
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# Forget the peer if long-term unreachable
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if peer.last_good and not peer.bad:
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try_limit = 10
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else:
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try_limit = 3
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if peer.try_count >= try_limit:
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desc = 'bad' if peer.bad else 'unreachable'
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self.logger.info(f'forgetting {desc} peer: {peer}')
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return True
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return False
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async def _verify_peer(self, session, peer):
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if not peer.is_tor:
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address = session.peer_address()
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if address:
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peer.ip_addr = address[0]
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# server.version goes first
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message = 'server.version'
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result = await session.send_request(message, self.server_version_args)
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assert_good(message, result, list)
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# Protocol version 1.1 returns a pair with the version first
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if len(result) != 2 or not all(isinstance(x, str) for x in result):
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raise BadPeerError(f'bad server.version result: {result}')
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server_version, protocol_version = result
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peer.server_version = server_version
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peer.features['server_version'] = server_version
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ptuple = protocol_tuple(protocol_version)
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await asyncio.wait([
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self._send_headers_subscribe(session, peer, ptuple),
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self._send_server_features(session, peer),
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self._send_peers_subscribe(session, peer)
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])
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async def _send_headers_subscribe(self, session, peer, ptuple):
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message = 'blockchain.headers.subscribe'
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result = await session.send_request(message)
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assert_good(message, result, dict)
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our_height = self.db.db_height
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if ptuple < (1, 3):
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their_height = result.get('block_height')
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else:
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their_height = result.get('height')
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if not isinstance(their_height, int):
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raise BadPeerError(f'invalid height {their_height}')
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if abs(our_height - their_height) > 5:
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raise BadPeerError(f'bad height {their_height:,d} '
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f'(ours: {our_height:,d})')
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# Check prior header too in case of hard fork.
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check_height = min(our_height, their_height)
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raw_header = await self.db.raw_header(check_height)
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if ptuple >= (1, 4):
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ours = raw_header.hex()
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message = 'blockchain.block.header'
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theirs = await session.send_request(message, [check_height])
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assert_good(message, theirs, str)
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if ours != theirs:
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raise BadPeerError(f'our header {ours} and '
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f'theirs {theirs} differ')
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else:
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ours = self.env.coin.electrum_header(raw_header, check_height)
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ours = ours.get('prev_block_hash')
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message = 'blockchain.block.get_header'
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theirs = await session.send_request(message, [check_height])
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assert_good(message, theirs, dict)
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theirs = theirs.get('prev_block_hash')
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if ours != theirs:
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raise BadPeerError(f'our header hash {ours} and '
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f'theirs {theirs} differ')
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async def _send_server_features(self, session, peer):
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message = 'server.features'
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features = await session.send_request(message)
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assert_good(message, features, dict)
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hosts = [host.lower() for host in features.get('hosts', {})]
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if self.env.coin.GENESIS_HASH != features.get('genesis_hash'):
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raise BadPeerError('incorrect genesis hash')
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elif peer.host.lower() in hosts:
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peer.update_features(features)
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else:
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raise BadPeerError(f'not listed in own hosts list {hosts}')
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async def _send_peers_subscribe(self, session, peer):
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message = 'server.peers.subscribe'
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raw_peers = await session.send_request(message)
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assert_good(message, raw_peers, list)
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# Check the peers list we got from a remote peer.
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# Each is expected to be of the form:
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# [ip_addr, hostname, ['v1.0', 't51001', 's51002']]
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# Call add_peer if the remote doesn't appear to know about us.
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try:
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real_names = [' '.join([u[1]] + u[2]) for u in raw_peers]
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peers = [Peer.from_real_name(real_name, str(peer))
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for real_name in real_names]
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except Exception:
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raise BadPeerError('bad server.peers.subscribe response')
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await self._note_peers(peers)
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features = self._features_to_register(peer, peers)
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if not features:
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return
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self.logger.info(f'registering ourself with {peer}')
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# We only care to wait for the response
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await session.send_request('server.add_peer', [features])
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#
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# External interface
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#
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async def discover_peers(self):
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"""Perform peer maintenance. This includes
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1) Forgetting unreachable peers.
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2) Verifying connectivity of new peers.
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3) Retrying old peers at regular intervals.
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"""
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if self.env.peer_discovery != self.env.PD_ON:
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self.logger.info('peer discovery is disabled')
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return
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self.logger.info(f'beginning peer discovery. Force use of '
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f'proxy: {self.env.force_proxy}')
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self.group.add(self._detect_proxy())
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self.group.add(self._import_peers())
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def info(self):
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"""The number of peers."""
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self._set_peer_statuses()
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counter = Counter(peer.status for peer in self.peers)
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return {
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'bad': counter[PEER_BAD],
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'good': counter[PEER_GOOD],
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'never': counter[PEER_NEVER],
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'stale': counter[PEER_STALE],
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'total': len(self.peers),
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}
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async def add_localRPC_peer(self, real_name):
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"""Add a peer passed by the admin over LocalRPC."""
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await self._note_peers([Peer.from_real_name(real_name, 'RPC')])
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async def on_add_peer(self, features, source_info):
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"""Add a peer (but only if the peer resolves to the source)."""
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if not source_info:
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self.logger.info('ignored add_peer request: no source info')
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return False
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source = source_info[0]
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peers = Peer.peers_from_features(features, source)
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if not peers:
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self.logger.info('ignored add_peer request: no peers given')
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return False
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# Just look at the first peer, require it
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peer = peers[0]
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host = peer.host
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if peer.is_tor:
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permit = self._permit_new_onion_peer()
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reason = 'rate limiting'
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else:
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getaddrinfo = asyncio.get_event_loop().getaddrinfo
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try:
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infos = await getaddrinfo(host, 80, type=socket.SOCK_STREAM)
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except socket.gaierror:
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permit = False
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reason = 'address resolution failure'
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else:
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permit = any(source == info[-1][0] for info in infos)
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reason = 'source-destination mismatch'
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if permit:
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self.logger.info(f'accepted add_peer request from {source} '
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f'for {host}')
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await self._note_peers([peer], check_ports=True)
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else:
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self.logger.warning(f'rejected add_peer request from {source} '
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f'for {host} ({reason})')
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return permit
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def on_peers_subscribe(self, is_tor):
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"""Returns the server peers as a list of (ip, host, details) tuples.
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We return all peers we've connected to in the last day.
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Additionally, if we don't have onion routing, we return a few
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hard-coded onion servers.
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"""
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cutoff = time.time() - STALE_SECS
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recent = [peer for peer in self.peers
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if peer.last_good > cutoff and
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not peer.bad and peer.is_public]
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onion_peers = []
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# Always report ourselves if valid (even if not public)
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peers = set(myself for myself in self.myselves
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if myself.last_good > cutoff)
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# Bucket the clearnet peers and select up to two from each
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buckets = defaultdict(list)
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for peer in recent:
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if peer.is_tor:
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onion_peers.append(peer)
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else:
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buckets[peer.bucket()].append(peer)
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for bucket_peers in buckets.values():
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random.shuffle(bucket_peers)
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peers.update(bucket_peers[:2])
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# Add up to 20% onion peers (but up to 10 is OK anyway)
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random.shuffle(onion_peers)
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max_onion = 50 if is_tor else max(10, len(peers) // 4)
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peers.update(onion_peers[:max_onion])
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return [peer.to_tuple() for peer in peers]
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def proxy_peername(self):
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"""Return the peername of the proxy, if there is a proxy, otherwise
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None."""
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return self.proxy.peername if self.proxy else None
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def rpc_data(self):
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"""Peer data for the peers RPC method."""
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self._set_peer_statuses()
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descs = ['good', 'stale', 'never', 'bad']
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def peer_data(peer):
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data = peer.serialize()
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data['status'] = descs[peer.status]
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return data
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def peer_key(peer):
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return (peer.bad, -peer.last_good)
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return [peer_data(peer) for peer in sorted(self.peers, key=peer_key)]
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