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Fix bad peer looping

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JWU42 pointed out an issue where peer discovery could get in a
failure loop for bad peers; this fixes the the root cause and
the immediate retries
This commit is contained in:
Neil Booth 2017-03-25 20:22:38 +09:00
parent 7b263c5c49
commit 3236989165
1 changed files with 14 additions and 29 deletions
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43
server/peers.py
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@ -56,7 +56,7 @@ class PeerSession(JSONSession):
self.peer = peer
self.peer_mgr = peer_mgr
self.kind = kind
self.failed = False
self.bad = False
self.log_prefix = '[{}] '.format(self.peer)
async def wait_on_items(self):
@ -82,6 +82,7 @@ class PeerSession(JSONSession):
[version.VERSION, proto_ver])
self.send_request(self.on_features, 'server.features')
self.send_request(self.on_headers, 'blockchain.headers.subscribe')
self.send_request(self.on_peers_subscribe, 'server.peers.subscribe')
def connection_lost(self, exc):
'''Handle disconnection.'''
@ -91,7 +92,7 @@ class PeerSession(JSONSession):
def on_peers_subscribe(self, result, error):
'''Handle the response to the peers.subcribe message.'''
if error:
self.failed = True
self.bad = True
self.log_error('server.peers.subscribe: {}'.format(error))
else:
self.check_remote_peers(result)
@ -133,54 +134,40 @@ class PeerSession(JSONSession):
'''Handle the response to the add_peer message.'''
self.close_if_done()
def peer_verified(self, is_good):
'''Call when it has been determined whether or not the peer seems to
be on the same network.
'''
if is_good:
self.send_request(self.on_peers_subscribe,
'server.peers.subscribe')
else:
self.peer.mark_bad()
self.failed = True
def on_features(self, features, error):
# Several peers don't implement this. If they do, check they are
# the same network with the genesis hash.
verified = False
if not error and isinstance(features, dict):
our_hash = self.peer_mgr.env.coin.GENESIS_HASH
if our_hash != features.get('genesis_hash'):
self.peer_verified(False)
self.bad = True
self.log_warning('incorrect genesis hash')
else:
self.peer_verified(True)
self.peer.update_features(features)
verified = True
self.close_if_done()
def on_headers(self, result, error):
'''Handle the response to the version message.'''
if error:
self.failed = True
self.bad = True
self.log_error('blockchain.headers.subscribe returned an error')
elif not isinstance(result, dict):
self.bad = True
self.log_error('bad blockchain.headers.subscribe response')
self.peer_verified(False)
else:
our_height = self.peer_mgr.controller.bp.db_height
their_height = result.get('block_height')
is_good = (isinstance(their_height, int) and
abs(our_height - their_height) <= 5)
self.peer_verified(is_good)
if not is_good:
self.bad = True
self.log_warning('bad height {}'.format(their_height))
self.close_if_done()
def on_version(self, result, error):
'''Handle the response to the version message.'''
if error:
self.failed = True
self.bad = True
self.log_error('server.version returned an error')
elif isinstance(result, str):
self.peer.server_version = result
@ -189,14 +176,15 @@ class PeerSession(JSONSession):
def close_if_done(self):
if not self.has_pending_requests():
is_good = not self.failed
self.peer_mgr.set_connection_status(self.peer, is_good)
if self.bad:
peer.mark_bad()
self.peer_mgr.set_connection_status(self.peer, not self.bad)
if self.peer.is_tor:
how = 'via {} over Tor'.format(self.kind)
else:
how = 'via {} at {}'.format(self.kind,
self.peer_addr(anon=False))
status = 'verified' if is_good else 'failed to verify'
status = 'failed to verify' if self.bad else 'verified'
elapsed = time.time() - self.peer.last_try
self.log_info('{} {} in {:.1f}s'.format(status, how, elapsed))
self.close_connection()
@ -559,11 +547,8 @@ class PeerManager(util.LoggedClass):
def maybe_forget_peer(self, peer):
'''Forget the peer if appropriate, e.g. long-term unreachable.'''
if peer.bad:
forget = peer.last_connect < time.time() - STALE_SECS // 2
else:
try_limit = 10 if peer.last_connect else 3
forget = peer.try_count >= try_limit
try_limit = 10 if peer.last_connect else 3
forget = peer.try_count >= try_limit
if forget:
desc = 'bad' if peer.bad else 'unreachable'