p2p.py

from __future__ import division

import math
import random
import sys
import time

from twisted.internet import defer, protocol, reactor
from twisted.python import failure, log

import p2pool
from p2pool import data as p2pool_data
from p2pool.bitcoin import data as bitcoin_data
from p2pool.util import deferral, p2protocol, pack, variable

class PeerMisbehavingError(Exception):
    pass


def fragment(f, **kwargs):
    try:
        f(**kwargs)
    except p2protocol.TooLong:
        fragment(f, **dict((k, v[:len(v)//2]) for k, v in kwargs.iteritems()))
        fragment(f, **dict((k, v[len(v)//2:]) for k, v in kwargs.iteritems()))

class Protocol(p2protocol.Protocol):
    VERSION = 1300
    
    max_remembered_txs_size = 2500000
    
    def __init__(self, node, incoming):
        p2protocol.Protocol.__init__(self, node.net.PREFIX, 1000000, node.traffic_happened)
        self.node = node
        self.incoming = incoming
        
        self.other_version = None
        self.connected2 = False
    
    def connectionMade(self):
        self.factory.proto_made_connection(self)
        
        self.connection_lost_event = variable.Event()
        
        self.addr = self.transport.getPeer().host, self.transport.getPeer().port
        
        self.send_version(
            version=self.VERSION,
            services=0,
            addr_to=dict(
                services=0,
                address=self.transport.getPeer().host,
                port=self.transport.getPeer().port,
            ),
            addr_from=dict(
                services=0,
                address=self.transport.getHost().host,
                port=self.transport.getHost().port,
            ),
            nonce=self.node.nonce,
            sub_version=p2pool.__version__,
            mode=1,
            best_share_hash=self.node.best_share_hash_func(),
        )
        
        self.timeout_delayed = reactor.callLater(10, self._connect_timeout)
        
        self.get_shares = deferral.GenericDeferrer(
            max_id=2**256,
            func=lambda id, hashes, parents, stops: self.send_sharereq(id=id, hashes=hashes, parents=parents, stops=stops),
            timeout=15,
            on_timeout=self.disconnect,
        )
        
        self.remote_tx_hashes = set() # view of peer's known_txs # not actually initially empty, but sending txs instead of tx hashes won't hurt
        self.remote_remembered_txs_size = 0
        
        self.remembered_txs = {} # view of peer's mining_txs
        self.remembered_txs_size = 0
        self.known_txs_cache = {}
    
    def _connect_timeout(self):
        self.timeout_delayed = None
        print 'Handshake timed out, disconnecting from %s:%i' % self.addr
        self.disconnect()
    
    def packetReceived(self, command, payload2):
        try:
            if command != 'version' and not self.connected2:
                raise PeerMisbehavingError('first message was not version message')
            p2protocol.Protocol.packetReceived(self, command, payload2)
        except PeerMisbehavingError, e:
            print 'Peer %s:%i misbehaving, will drop and ban. Reason:' % self.addr, e.message
            self.badPeerHappened()
    
    def badPeerHappened(self):
        print "Bad peer banned:", self.addr
        self.disconnect()
        if self.transport.getPeer().host != '127.0.0.1': # never ban localhost
            self.node.bans[self.transport.getPeer().host] = time.time() + 60*60
    
    def _timeout(self):
        self.timeout_delayed = None
        print 'Connection timed out, disconnecting from %s:%i' % self.addr
        self.disconnect()
    
    message_version = pack.ComposedType([
        ('version', pack.IntType(32)),
        ('services', pack.IntType(64)),
        ('addr_to', bitcoin_data.address_type),
        ('addr_from', bitcoin_data.address_type),
        ('nonce', pack.IntType(64)),
        ('sub_version', pack.VarStrType()),
        ('mode', pack.IntType(32)), # always 1 for legacy compatibility
        ('best_share_hash', pack.PossiblyNoneType(0, pack.IntType(256))),
    ])
    def handle_version(self, version, services, addr_to, addr_from, nonce, sub_version, mode, best_share_hash):
        if self.other_version is not None:
            raise PeerMisbehavingError('more than one version message')
        if version < 1300:
            raise PeerMisbehavingError('peer too old')
        
        self.other_version = version
        self.other_sub_version = sub_version[:512]
        self.other_services = services
        
        if nonce == self.node.nonce:
            raise PeerMisbehavingError('was connected to self')
        if nonce in self.node.peers:
            if p2pool.DEBUG:
                print 'Detected duplicate connection, disconnecting from %s:%i' % self.addr
            self.disconnect()
            return
        
        self.nonce = nonce
        self.connected2 = True
        
        self.timeout_delayed.cancel()
        self.timeout_delayed = reactor.callLater(100, self._timeout)
        
        old_dataReceived = self.dataReceived
        def new_dataReceived(data):
            if self.timeout_delayed is not None:
                self.timeout_delayed.reset(100)
            old_dataReceived(data)
        self.dataReceived = new_dataReceived
        
        self.factory.proto_connected(self)
        
        self._stop_thread = deferral.run_repeatedly(lambda: [
            self.send_ping(),
        random.expovariate(1/100)][-1])
        
        if self.node.advertise_ip:
            self._stop_thread2 = deferral.run_repeatedly(lambda: [
                self.send_addrme(port=self.node.serverfactory.listen_port.getHost().port) if self.node.serverfactory.listen_port is not None else None,
            random.expovariate(1/(100*len(self.node.peers) + 1))][-1])
        
        if best_share_hash is not None:
            self.node.handle_share_hashes([best_share_hash], self)
        
        def update_remote_view_of_my_known_txs(before, after):
            added = set(after) - set(before)
            removed = set(before) - set(after)
            if added:
                self.send_have_tx(tx_hashes=list(added))
            if removed:
                self.send_losing_tx(tx_hashes=list(removed))
                
                # cache forgotten txs here for a little while so latency of "losing_tx" packets doesn't cause problems
                key = max(self.known_txs_cache) + 1 if self.known_txs_cache else 0
                self.known_txs_cache[key] = dict((h, before[h]) for h in removed)
                reactor.callLater(20, self.known_txs_cache.pop, key)
        watch_id = self.node.known_txs_var.transitioned.watch(update_remote_view_of_my_known_txs)
        self.connection_lost_event.watch(lambda: self.node.known_txs_var.transitioned.unwatch(watch_id))
        
        self.send_have_tx(tx_hashes=self.node.known_txs_var.value.keys())
        
        def update_remote_view_of_my_mining_txs(before, after):
            added = set(after) - set(before)
            removed = set(before) - set(after)
            if added:
                self.remote_remembered_txs_size += sum(100 + bitcoin_data.tx_type.packed_size(after[x]) for x in added)
                assert self.remote_remembered_txs_size <= self.max_remembered_txs_size
                fragment(self.send_remember_tx, tx_hashes=[x for x in added if x in self.remote_tx_hashes], txs=[after[x] for x in added if x not in self.remote_tx_hashes])
            if removed:
                self.send_forget_tx(tx_hashes=list(removed))
                self.remote_remembered_txs_size -= sum(100 + bitcoin_data.tx_type.packed_size(before[x]) for x in removed)
        watch_id2 = self.node.mining_txs_var.transitioned.watch(update_remote_view_of_my_mining_txs)
        self.connection_lost_event.watch(lambda: self.node.mining_txs_var.transitioned.unwatch(watch_id2))
        
        self.remote_remembered_txs_size += sum(100 + bitcoin_data.tx_type.packed_size(x) for x in self.node.mining_txs_var.value.values())
        assert self.remote_remembered_txs_size <= self.max_remembered_txs_size
        fragment(self.send_remember_tx, tx_hashes=[], txs=self.node.mining_txs_var.value.values())
    
    message_ping = pack.ComposedType([])
    def handle_ping(self):
        pass
    
    message_addrme = pack.ComposedType([
        ('port', pack.IntType(16)),
    ])
    def handle_addrme(self, port):
        host = self.transport.getPeer().host
        #print 'addrme from', host, port
        if host == '127.0.0.1':
            if random.random() < .8 and self.node.peers:
                random.choice(self.node.peers.values()).send_addrme(port=port) # services...
        else:
            self.node.got_addr((self.transport.getPeer().host, port), self.other_services, int(time.time()))
            if random.random() < .8 and self.node.peers:
                random.choice(self.node.peers.values()).send_addrs(addrs=[
                    dict(
                        address=dict(
                            services=self.other_services,
                            address=host,
                            port=port,
                        ),
                        timestamp=int(time.time()),
                    ),
                ])
    
    message_addrs = pack.ComposedType([
        ('addrs', pack.ListType(pack.ComposedType([
            ('timestamp', pack.IntType(64)),
            ('address', bitcoin_data.address_type),
        ]))),
    ])
    def handle_addrs(self, addrs):
        for addr_record in addrs:
            self.node.got_addr((addr_record['address']['address'], addr_record['address']['port']), addr_record['address']['services'], min(int(time.time()), addr_record['timestamp']))
            if random.random() < .8 and self.node.peers:
                random.choice(self.node.peers.values()).send_addrs(addrs=[addr_record])
    
    message_getaddrs = pack.ComposedType([
        ('count', pack.IntType(32)),
    ])
    def handle_getaddrs(self, count):
        if count > 100:
            count = 100
        self.send_addrs(addrs=[
            dict(
                timestamp=int(self.node.addr_store[host, port][2]),
                address=dict(
                    services=self.node.addr_store[host, port][0],
                    address=host,
                    port=port,
                ),
            ) for host, port in
            self.node.get_good_peers(count)
        ])
    
    message_shares = pack.ComposedType([
        ('shares', pack.ListType(p2pool_data.share_type)),
    ])
    def handle_shares(self, shares):
        result = []
        for wrappedshare in shares:
            if wrappedshare['type'] < p2pool_data.Share.VERSION: continue
            share = p2pool_data.load_share(wrappedshare, self.node.net, self.addr)
            if wrappedshare['type'] >= 13:
                txs = []
                for tx_hash in share.share_info['new_transaction_hashes']:
                    if tx_hash in self.node.known_txs_var.value:
                        tx = self.node.known_txs_var.value[tx_hash]
                    else:
                        for cache in self.known_txs_cache.itervalues():
                            if tx_hash in cache:
                                tx = cache[tx_hash]
                                print 'Transaction %064x rescued from peer latency cache!' % (tx_hash,)
                                break
                        else:
                            print >>sys.stderr, 'Peer referenced unknown transaction %064x, disconnecting' % (tx_hash,)
                            self.disconnect()
                            return
                    txs.append(tx)
            else:
                txs = None
            
            result.append((share, txs))
            
        self.node.handle_shares(result, self)
    
    def sendShares(self, shares, tracker, known_txs, include_txs_with=[]):
        tx_hashes = set()
        for share in shares:
            if share.VERSION >= 13:
                # send full transaction for every new_transaction_hash that peer does not know
                for tx_hash in share.share_info['new_transaction_hashes']:
                    assert tx_hash in known_txs, 'tried to broadcast share without knowing all its new transactions'
                    if tx_hash not in self.remote_tx_hashes:
                        tx_hashes.add(tx_hash)
                continue
            if share.hash in include_txs_with:
                x = share.get_other_tx_hashes(tracker)
                if x is not None:
                    tx_hashes.update(x)
        
        hashes_to_send = [x for x in tx_hashes if x not in self.node.mining_txs_var.value and x in known_txs]
        
        new_remote_remembered_txs_size = self.remote_remembered_txs_size + sum(100 + bitcoin_data.tx_type.packed_size(known_txs[x]) for x in hashes_to_send)
        if new_remote_remembered_txs_size > self.max_remembered_txs_size:
            raise ValueError('shares have too many txs')
        self.remote_remembered_txs_size = new_remote_remembered_txs_size
        
        fragment(self.send_remember_tx, tx_hashes=[x for x in hashes_to_send if x in self.remote_tx_hashes], txs=[known_txs[x] for x in hashes_to_send if x not in self.remote_tx_hashes])
        
        fragment(self.send_shares, shares=[share.as_share() for share in shares])
        
        self.send_forget_tx(tx_hashes=hashes_to_send)
        
        self.remote_remembered_txs_size -= sum(100 + bitcoin_data.tx_type.packed_size(known_txs[x]) for x in hashes_to_send)
    
    
    message_sharereq = pack.ComposedType([
        ('id', pack.IntType(256)),
        ('hashes', pack.ListType(pack.IntType(256))),
        ('parents', pack.VarIntType()),
        ('stops', pack.ListType(pack.IntType(256))),
    ])
    def handle_sharereq(self, id, hashes, parents, stops):
        shares = self.node.handle_get_shares(hashes, parents, stops, self)
        try:
            self.send_sharereply(id=id, result='good', shares=[share.as_share() for share in shares])
        except p2protocol.TooLong:
            self.send_sharereply(id=id, result='too long', shares=[])
    
    message_sharereply = pack.ComposedType([
        ('id', pack.IntType(256)),
        ('result', pack.EnumType(pack.VarIntType(), {0: 'good', 1: 'too long', 2: 'unk2', 3: 'unk3', 4: 'unk4', 5: 'unk5', 6: 'unk6'})),
        ('shares', pack.ListType(p2pool_data.share_type)),
    ])
    class ShareReplyError(Exception): pass
    def handle_sharereply(self, id, result, shares):
        if result == 'good':
            res = [p2pool_data.load_share(share, self.node.net, self.addr) for share in shares if share['type'] >= p2pool_data.Share.VERSION]
        else:
            res = failure.Failure(self.ShareReplyError(result))
        self.get_shares.got_response(id, res)
    
    
    message_bestblock = pack.ComposedType([
        ('header', bitcoin_data.block_header_type),
    ])
    def handle_bestblock(self, header):
        self.node.handle_bestblock(header, self)
    
    
    message_have_tx = pack.ComposedType([
        ('tx_hashes', pack.ListType(pack.IntType(256))),
    ])
    def handle_have_tx(self, tx_hashes):
        #assert self.remote_tx_hashes.isdisjoint(tx_hashes)
        self.remote_tx_hashes.update(tx_hashes)
        while len(self.remote_tx_hashes) > 10000:
            self.remote_tx_hashes.pop()
    message_losing_tx = pack.ComposedType([
        ('tx_hashes', pack.ListType(pack.IntType(256))),
    ])
    def handle_losing_tx(self, tx_hashes):
        #assert self.remote_tx_hashes.issuperset(tx_hashes)
        self.remote_tx_hashes.difference_update(tx_hashes)
    
    
    message_remember_tx = pack.ComposedType([
        ('tx_hashes', pack.ListType(pack.IntType(256))),
        ('txs', pack.ListType(bitcoin_data.tx_type)),
    ])
    def handle_remember_tx(self, tx_hashes, txs):
        for tx_hash in tx_hashes:
            if tx_hash in self.remembered_txs:
                print >>sys.stderr, 'Peer referenced transaction twice, disconnecting'
                self.disconnect()
                return
            
            if tx_hash in self.node.known_txs_var.value:
                tx = self.node.known_txs_var.value[tx_hash]
            else:
                for cache in self.known_txs_cache.itervalues():
                    if tx_hash in cache:
                        tx = cache[tx_hash]
                        print 'Transaction %064x rescued from peer latency cache!' % (tx_hash,)
                        break
                else:
                    print >>sys.stderr, 'Peer referenced unknown transaction %064x, disconnecting' % (tx_hash,)
                    self.disconnect()
                    return
            
            self.remembered_txs[tx_hash] = tx
            self.remembered_txs_size += 100 + bitcoin_data.tx_type.packed_size(tx)
        new_known_txs = dict(self.node.known_txs_var.value)
        warned = False
        for tx in txs:
            tx_hash = bitcoin_data.hash256(bitcoin_data.tx_type.pack(tx))
            if tx_hash in self.remembered_txs:
                print >>sys.stderr, 'Peer referenced transaction twice, disconnecting'
                self.disconnect()
                return
            
            if tx_hash in self.node.known_txs_var.value and not warned:
                print 'Peer sent entire transaction %064x that was already received' % (tx_hash,)
                warned = True
            
            self.remembered_txs[tx_hash] = tx
            self.remembered_txs_size += 100 + bitcoin_data.tx_type.packed_size(tx)
            new_known_txs[tx_hash] = tx
        self.node.known_txs_var.set(new_known_txs)
        if self.remembered_txs_size >= self.max_remembered_txs_size:
            raise PeerMisbehavingError('too much transaction data stored')
    message_forget_tx = pack.ComposedType([
        ('tx_hashes', pack.ListType(pack.IntType(256))),
    ])
    def handle_forget_tx(self, tx_hashes):
        for tx_hash in tx_hashes:
            self.remembered_txs_size -= 100 + bitcoin_data.tx_type.packed_size(self.remembered_txs[tx_hash])
            assert self.remembered_txs_size >= 0
            del self.remembered_txs[tx_hash]
    
    
    def connectionLost(self, reason):
        self.connection_lost_event.happened()
        if self.timeout_delayed is not None:
            self.timeout_delayed.cancel()
        if self.connected2:
            self.factory.proto_disconnected(self, reason)
            self._stop_thread()
            if self.node.advertise_ip:
                self._stop_thread2()
            self.connected2 = False
        self.factory.proto_lost_connection(self, reason)
        if p2pool.DEBUG:
            print "Peer connection lost:", self.addr, reason
        self.get_shares.respond_all(reason)
    
    @defer.inlineCallbacks
    def do_ping(self):
        start = reactor.seconds()
        yield self.get_shares(hashes=[0], parents=0, stops=[])
        end = reactor.seconds()
        defer.returnValue(end - start)

class ServerFactory(protocol.ServerFactory):
    def __init__(self, node, max_conns):
        self.node = node
        self.max_conns = max_conns
        
        self.conns = {}
        self.running = False
        self.listen_port = None
    
    def buildProtocol(self, addr):
        if sum(self.conns.itervalues()) >= self.max_conns or self.conns.get(self._host_to_ident(addr.host), 0) >= 3:
            return None
        if addr.host in self.node.bans and self.node.bans[addr.host] > time.time():
            return None
        p = Protocol(self.node, True)
        p.factory = self
        if p2pool.DEBUG:
            print "Got peer connection from:", addr
        return p
    
    def _host_to_ident(self, host):
        a, b, c, d = host.split('.')
        return a, b
    
    def proto_made_connection(self, proto):
        ident = self._host_to_ident(proto.transport.getPeer().host)
        self.conns[ident] = self.conns.get(ident, 0) + 1
    def proto_lost_connection(self, proto, reason):
        ident = self._host_to_ident(proto.transport.getPeer().host)
        self.conns[ident] -= 1
        if not self.conns[ident]:
            del self.conns[ident]
    
    def proto_connected(self, proto):
        self.node.got_conn(proto)
    def proto_disconnected(self, proto, reason):
        self.node.lost_conn(proto, reason)
    
    def start(self):
        assert not self.running
        self.running = True
        
        def attempt_listen():
            if self.running:
                self.listen_port = reactor.listenTCP(self.node.port, self)
        deferral.retry('Error binding to P2P port:', traceback=False)(attempt_listen)()
    
    def stop(self):
        assert self.running
        self.running = False
        
        return self.listen_port.stopListening()

class ClientFactory(protocol.ClientFactory):
    def __init__(self, node, desired_conns, max_attempts):
        self.node = node
        self.desired_conns = desired_conns
        self.max_attempts = max_attempts
        
        self.attempts = set()
        self.conns = set()
        self.running = False
    
    def _host_to_ident(self, host):
        a, b, c, d = host.split('.')
        return a, b
    
    def buildProtocol(self, addr):
        p = Protocol(self.node, False)
        p.factory = self
        return p
    
    def startedConnecting(self, connector):
        ident = self._host_to_ident(connector.getDestination().host)
        if ident in self.attempts:
            raise AssertionError('already have attempt')
        self.attempts.add(ident)
    
    def clientConnectionFailed(self, connector, reason):
        self.attempts.remove(self._host_to_ident(connector.getDestination().host))
    
    def clientConnectionLost(self, connector, reason):
        self.attempts.remove(self._host_to_ident(connector.getDestination().host))
    
    def proto_made_connection(self, proto):
        pass
    def proto_lost_connection(self, proto, reason):
        pass
    
    def proto_connected(self, proto):
        self.conns.add(proto)
        self.node.got_conn(proto)
    def proto_disconnected(self, proto, reason):
        self.conns.remove(proto)
        self.node.lost_conn(proto, reason)
    
    def start(self):
        assert not self.running
        self.running = True
        self._stop_thinking = deferral.run_repeatedly(self._think)
    def stop(self):
        assert self.running
        self.running = False
        self._stop_thinking()
    
    def _think(self):
        try:
            if len(self.conns) < self.desired_conns and len(self.attempts) < self.max_attempts and self.node.addr_store:
                (host, port), = self.node.get_good_peers(1)
                
                if self._host_to_ident(host) in self.attempts:
                    pass
                elif host in self.node.bans and self.node.bans[host] > time.time():
                    pass
                else:
                    #print 'Trying to connect to', host, port
                    reactor.connectTCP(host, port, self, timeout=5)
        except:
            log.err()
        
        return random.expovariate(1/1)

class SingleClientFactory(protocol.ReconnectingClientFactory):
    def __init__(self, node):
        self.node = node
    
    def buildProtocol(self, addr):
        p = Protocol(self.node, incoming=False)
        p.factory = self
        return p
    
    def proto_made_connection(self, proto):
        pass
    def proto_lost_connection(self, proto, reason):
        pass
    
    def proto_connected(self, proto):
        self.resetDelay()
        self.node.got_conn(proto)
    def proto_disconnected(self, proto, reason):
        self.node.lost_conn(proto, reason)

class Node(object):
    def __init__(self, best_share_hash_func, port, net, addr_store={}, connect_addrs=set(), desired_outgoing_conns=10, max_outgoing_attempts=30, max_incoming_conns=50, preferred_storage=1000, known_txs_var=variable.Variable({}), mining_txs_var=variable.Variable({}), advertise_ip=True):
        self.best_share_hash_func = best_share_hash_func
        self.port = port
        self.net = net
        self.addr_store = dict(addr_store)
        self.connect_addrs = connect_addrs
        self.preferred_storage = preferred_storage
        self.known_txs_var = known_txs_var
        self.mining_txs_var = mining_txs_var
        self.advertise_ip = advertise_ip
        
        self.traffic_happened = variable.Event()
        self.nonce = random.randrange(2**64)
        self.peers = {}
        self.bans = {} # address -> end_time
        self.clientfactory = ClientFactory(self, desired_outgoing_conns, max_outgoing_attempts)
        self.serverfactory = ServerFactory(self, max_incoming_conns)
        self.running = False
    
    def start(self):
        if self.running:
            raise ValueError('already running')
        
        self.clientfactory.start()
        self.serverfactory.start()
        self.singleclientconnectors = [reactor.connectTCP(addr, port, SingleClientFactory(self)) for addr, port in self.connect_addrs]
        
        self.running = True
        
        self._stop_thinking = deferral.run_repeatedly(self._think)
    
    def _think(self):
        try:
            if len(self.addr_store) < self.preferred_storage and self.peers:
                random.choice(self.peers.values()).send_getaddrs(count=8)
        except:
            log.err()
        
        return random.expovariate(1/20)
    
    @defer.inlineCallbacks
    def stop(self):
        if not self.running:
            raise ValueError('already stopped')
        
        self.running = False
        
        self._stop_thinking()
        yield self.clientfactory.stop()
        yield self.serverfactory.stop()
        for singleclientconnector in self.singleclientconnectors:
            yield singleclientconnector.factory.stopTrying()
            yield singleclientconnector.disconnect()
        del self.singleclientconnectors
    
    def got_conn(self, conn):
        if conn.nonce in self.peers:
            raise ValueError('already have peer')
        self.peers[conn.nonce] = conn
        
        print '%s connection to peer %s:%i established. p2pool version: %i %r' % ('Incoming' if conn.incoming else 'Outgoing', conn.addr[0], conn.addr[1], conn.other_version, conn.other_sub_version)
    
    def lost_conn(self, conn, reason):
        if conn.nonce not in self.peers:
            raise ValueError('''don't have peer''')
        if conn is not self.peers[conn.nonce]:
            raise ValueError('wrong conn')
        del self.peers[conn.nonce]
        
        print 'Lost peer %s:%i - %s' % (conn.addr[0], conn.addr[1], reason.getErrorMessage())
    
    
    def got_addr(self, (host, port), services, timestamp):
        if (host, port) in self.addr_store:
            old_services, old_first_seen, old_last_seen = self.addr_store[host, port]
            self.addr_store[host, port] = services, old_first_seen, max(old_last_seen, timestamp)
        else:
            if len(self.addr_store) < 10000:
                self.addr_store[host, port] = services, timestamp, timestamp
    
    def handle_shares(self, shares, peer):
        print 'handle_shares', (shares, peer)
    
    def handle_share_hashes(self, hashes, peer):
        print 'handle_share_hashes', (hashes, peer)
    
    def handle_get_shares(self, hashes, parents, stops, peer):
        print 'handle_get_shares', (hashes, parents, stops, peer)
    
    def handle_bestblock(self, header, peer):
        print 'handle_bestblock', header
    
    def get_good_peers(self, max_count):
        t = time.time()
        return [x[0] for x in sorted(self.addr_store.iteritems(), key=lambda (k, (services, first_seen, last_seen)):
            -math.log(max(3600, last_seen - first_seen))/math.log(max(3600, t - last_seen))*random.expovariate(1)
        )][:max_count]