p2pool/data.py

   1 from __future__ import division
   2
   3 import itertools
   4 import random
   5 import time
   6 import os
   7
   8 from twisted.python import log
   9
  10 import p2pool
  11 from p2pool import skiplists
  12 from p2pool.bitcoin import data as bitcoin_data, script, networks
  13 from p2pool.util import memoize, expiring_dict, math
  14
  15
  16 merkle_branch_type = bitcoin_data.ListType(bitcoin_data.ComposedType([
  17     ('side', bitcoin_data.StructType('<B')), # enum?
  18     ('hash', bitcoin_data.HashType()),
  19 ]))
  20
  21
  22 share_data_type = bitcoin_data.ComposedType([
  23     ('previous_share_hash', bitcoin_data.PossiblyNoneType(0, bitcoin_data.HashType())),
  24     ('target', bitcoin_data.FloatingIntegerType()),
  25     ('nonce', bitcoin_data.VarStrType()),
  26 ])
  27
  28
  29 coinbase_type = bitcoin_data.ComposedType([
  30     ('identifier', bitcoin_data.FixedStrType(8)),
  31     ('share_data', share_data_type),
  32 ])
  33
  34 share_info_type = bitcoin_data.ComposedType([
  35     ('share_data', share_data_type),
  36     ('new_script', bitcoin_data.VarStrType()),
  37     ('subsidy', bitcoin_data.StructType('<Q')),
  38 ])
  39
  40
  41 share1a_type = bitcoin_data.ComposedType([
  42     ('header', bitcoin_data.block_header_type),
  43     ('share_info', share_info_type),
  44     ('merkle_branch', merkle_branch_type),
  45 ])
  46
  47 share1b_type = bitcoin_data.ComposedType([
  48     ('header', bitcoin_data.block_header_type),
  49     ('share_info', share_info_type),
  50     ('other_txs', bitcoin_data.ListType(bitcoin_data.tx_type)),
  51 ])
  52
  53 new_share_data_type = bitcoin_data.ComposedType([
  54     ('previous_share_hash', bitcoin_data.PossiblyNoneType(0, bitcoin_data.HashType())),
  55     ('coinbase', bitcoin_data.VarStrType()),
  56     ('nonce', bitcoin_data.VarStrType()),
  57     ('new_script', bitcoin_data.VarStrType()),
  58     ('subsidy', bitcoin_data.StructType('<Q')),
  59     ('donation', bitcoin_data.StructType('<H')),
  60 ])
  61
  62 new_share_info_type = bitcoin_data.ComposedType([
  63     ('new_share_data', new_share_data_type),
  64     ('target', bitcoin_data.FloatingIntegerType()),
  65 ])
  66
  67 new_share1a_type = bitcoin_data.ComposedType([
  68     ('header', bitcoin_data.block_header_type),
  69     ('share_info', new_share_info_type),
  70     ('merkle_branch', bitcoin_data.merkle_branch_type),
  71 ])
  72
  73 new_share1b_type = bitcoin_data.ComposedType([
  74     ('header', bitcoin_data.block_header_type),
  75     ('share_info', new_share_info_type),
  76     ('other_txs', bitcoin_data.ListType(bitcoin_data.tx_type)),
  77 ])
  78
  79 def calculate_merkle_branch(txs, index):
  80     hash_list = [(bitcoin_data.tx_type.hash256(tx), i == index, []) for i, tx in enumerate(txs)]
  81
  82     while len(hash_list) > 1:
  83         hash_list = [
  84             (
  85                 bitcoin_data.merkle_record_type.hash256(dict(left=left, right=right)),
  86                 left_f or right_f,
  87                 (left_l if left_f else right_l) + [dict(side=1, hash=right) if left_f else dict(side=0, hash=left)],
  88             )
  89             for (left, left_f, left_l), (right, right_f, right_l) in
  90                 zip(hash_list[::2], hash_list[1::2] + [hash_list[::2][-1]])
  91         ]
  92
  93     assert hash_list[0][1]
  94     assert check_merkle_branch(txs[index], hash_list[0][2]) == hash_list[0][0]
  95
  96     return hash_list[0][2]
  97
  98 def check_merkle_branch(tx, branch):
  99     hash_ = bitcoin_data.tx_type.hash256(tx)
 100     for step in branch:
 101         if not step['side']:
 102             hash_ = bitcoin_data.merkle_record_type.hash256(dict(left=step['hash'], right=hash_))
 103         else:
 104             hash_ = bitcoin_data.merkle_record_type.hash256(dict(left=hash_, right=step['hash']))
 105     return hash_
 106
 107 def share_info_to_gentx(share_info, block_target, tracker, net):
 108     return generate_transaction(
 109         tracker=tracker,
 110         previous_share_hash=share_info['share_data']['previous_share_hash'],
 111         new_script=share_info['new_script'],
 112         subsidy=share_info['subsidy'],
 113         nonce=share_info['share_data']['nonce'],
 114         block_target=block_target,
 115         net=net,
 116     )[1]
 117
 118 class Share(object):
 119     donation = 0
 120
 121     @classmethod
 122     def from_share1a(cls, share1a, net):
 123         return cls(net, **share1a)
 124
 125     @classmethod
 126     def from_share1b(cls, share1b, net):
 127         return cls(net, **share1b)
 128
 129     __slots__ = 'header previous_block share_info merkle_branch other_txs timestamp share_data new_script subsidy previous_hash previous_share_hash target nonce pow_hash header_hash hash time_seen shared stored peer'.split(' ')
 130
 131     def __init__(self, net, header, share_info, merkle_branch=None, other_txs=None):
 132         if merkle_branch is None and other_txs is None:
 133             raise ValueError('need either merkle_branch or other_txs')
 134         if other_txs is not None:
 135             new_merkle_branch = calculate_merkle_branch([dict(version=0, tx_ins=[], tx_outs=[], lock_time=0)] + other_txs, 0)
 136             if merkle_branch is not None:
 137                 if merke_branch != new_merkle_branch:
 138                     raise ValueError('invalid merkle_branch and other_txs')
 139             merkle_branch = new_merkle_branch
 140
 141         if len(merkle_branch) > 16:
 142             raise ValueError('merkle_branch too long!')
 143
 144         self.header = header
 145         self.previous_block = header['previous_block']
 146         self.share_info = share_info
 147         self.merkle_branch = merkle_branch
 148         self.other_txs = other_txs
 149
 150         self.timestamp = self.header['timestamp']
 151
 152         self.share_data = self.share_info['share_data']
 153         self.new_script = self.share_info['new_script']
 154         self.subsidy = self.share_info['subsidy']
 155
 156         if len(self.new_script) > 100:
 157             raise ValueError('new_script too long!')
 158
 159         self.previous_hash = self.previous_share_hash = self.share_data['previous_share_hash']
 160         self.target = self.share_data['target']
 161         self.nonce = self.share_data['nonce']
 162
 163         if len(self.nonce) > 100:
 164             raise ValueError('nonce too long!')
 165
 166         self.pow_hash = net.BITCOIN_POW_FUNC(header)
 167         self.header_hash = bitcoin_data.block_header_type.hash256(header)
 168
 169         if net.BITCOIN_POW_FUNC is bitcoin_data.block_header_type.scrypt:
 170             # compatibility hack
 171             self.hash = share1a_type.scrypt(self.as_share1a())
 172         else:
 173             self.hash = share1a_type.hash256(self.as_share1a())
 174
 175         if self.pow_hash > self.target:
 176             print 'hash %x' % self.pow_hash
 177             print 'targ %x' % self.target
 178             raise ValueError('not enough work!')
 179
 180         if script.get_sigop_count(self.new_script) > 1:
 181             raise ValueError('too many sigops!')
 182
 183         # XXX eww
 184         self.time_seen = time.time()
 185         self.shared = False
 186         self.stored = False
 187         self.peer = None
 188
 189     def as_block(self, tracker, net):
 190         if self.other_txs is None:
 191             raise ValueError('share does not contain all txs')
 192
 193         gentx = share_info_to_gentx(self.share_info, self.header['target'], tracker, net)
 194
 195         return dict(header=self.header, txs=[gentx] + self.other_txs)
 196
 197     def as_share1a(self):
 198         return dict(header=self.header, share_info=self.share_info, merkle_branch=self.merkle_branch)
 199
 200     def as_share1b(self):
 201         if self.other_txs is None:
 202             raise ValueError('share does not contain all txs')
 203
 204         return dict(header=self.header, share_info=self.share_info, other_txs=self.other_txs)
 205
 206     def check(self, tracker, now, net):
 207         import time
 208         if self.previous_share_hash is not None:
 209             if self.header['timestamp'] <= math.median((s.timestamp for s in itertools.islice(tracker.get_chain_to_root(self.previous_share_hash), 11)), use_float=False):
 210                 raise ValueError('share from too far in the past!')
 211
 212         if self.header['timestamp'] > now + 2*60*60:
 213             raise ValueError('share from too far in the future!')
 214
 215         gentx = share_info_to_gentx(self.share_info, self.header['target'], tracker, net)
 216
 217         if len(gentx['tx_ins'][0]['script']) > 100:
 218             raise ValueError('coinbase too large! %i bytes' % (len(gentx['tx_ins'][0]['script']),))
 219
 220         if check_merkle_branch(gentx, self.merkle_branch) != self.header['merkle_root']:
 221             raise ValueError('''gentx doesn't match header via merkle_branch''')
 222
 223         if self.other_txs is not None:
 224             if bitcoin_data.merkle_hash([gentx] + self.other_txs) != self.header['merkle_root']:
 225                 raise ValueError('''gentx doesn't match header via other_txs''')
 226
 227             if len(bitcoin_data.block_type.pack(dict(header=self.header, txs=[gentx] + self.other_txs))) > 1000000 - 1000:
 228                 raise ValueError('block size too large')
 229
 230     def flag_shared(self):
 231         self.shared = True
 232
 233     def __repr__(self):
 234         return '<Share %s>' % (' '.join('%s=%r' % (k, getattr(self, k)) for k in self.__slots__),)
 235
 236 class NewShare(Share):
 237     def __init__(self, net, header, new_share_info, merkle_branch=None, other_txs=None):
 238         if merkle_branch is None and other_txs is None:
 239             raise ValueError('need either merkle_branch or other_txs')
 240         if other_txs is not None:
 241             new_merkle_branch = bitcoin_data.calculate_merkle_branch([dict(version=0, tx_ins=[], tx_outs=[], lock_time=0)] + other_txs, 0)
 242             if merkle_branch is not None:
 243                 if merke_branch != new_merkle_branch:
 244                     raise ValueError('invalid merkle_branch and other_txs')
 245             merkle_branch = new_merkle_branch
 246
 247         if len(merkle_branch) > 16:
 248             raise ValueError('merkle_branch too long!')
 249
 250         self.header = header
 251         self.previous_block = header['previous_block']
 252         self.share_info = new_share_info
 253         self.merkle_branch = merkle_branch
 254         self.other_txs = other_txs
 255
 256         self.timestamp = self.header['timestamp']
 257
 258         self.share_data = self.share_info['new_share_data']
 259         self.target = self.share_info['target']
 260
 261         self.new_script = self.share_data['new_script']
 262         self.subsidy = self.share_data['subsidy']
 263
 264         if len(self.new_script) > 100:
 265             raise ValueError('new_script too long!')
 266
 267         self.previous_hash = self.previous_share_hash = self.share_data['previous_share_hash']
 268         self.nonce = self.share_data['nonce']
 269
 270         if len(self.nonce) > 100:
 271             raise ValueError('nonce too long!')
 272
 273         if len(self.share_data['coinbase']) > 100:
 274             raise ValueError('''coinbase too large! %i bytes''' % (len(self.share_data['coinbase']),))
 275
 276         self.pow_hash = net.BITCOIN_POW_FUNC(header)
 277         self.header_hash = bitcoin_data.block_header_type.hash256(header)
 278
 279         self.hash = new_share1a_type.hash256(self.as_share1a())
 280
 281         if self.pow_hash > self.target:
 282             print 'hash %x' % self.pow_hash
 283             print 'targ %x' % self.target
 284             raise ValueError('not enough work!')
 285
 286         if script.get_sigop_count(self.new_script) > 1:
 287             raise ValueError('too many sigops!')
 288
 289         # XXX eww
 290         self.time_seen = time.time()
 291         self.shared = False
 292         self.stored = False
 293         self.peer = None
 294
 295     def check(self, tracker, now, net):
 296         import time
 297         if self.previous_share_hash is not None:
 298             if self.header['timestamp'] <= math.median((s.timestamp for s in itertools.islice(tracker.get_chain_to_root(self.previous_share_hash), 11)), use_float=False):
 299                 raise ValueError('share from too far in the past!')
 300
 301         if self.header['timestamp'] > now + 2*60*60:
 302             raise ValueError('share from too far in the future!')
 303
 304         new_share_info, gentx = new_generate_transaction(tracker, self.share_info['new_share_data'], self.header['target'], net)
 305         if new_share_info != self.share_info:
 306             raise ValueError('share difficulty invalid')
 307
 308         if bitcoin_data.check_merkle_branch(gentx, 0, self.merkle_branch) != self.header['merkle_root']:
 309             raise ValueError('''gentx doesn't match header via merkle_branch''')
 310
 311         if self.other_txs is not None:
 312             if bitcoin_data.merkle_hash([gentx] + self.other_txs) != self.header['merkle_root']:
 313                 raise ValueError('''gentx doesn't match header via other_txs''')
 314
 315             if len(bitcoin_data.block_type.pack(dict(header=self.header, txs=[gentx] + self.other_txs))) > 1000000 - 1000:
 316                 raise ValueError('''block size too large''')
 317
 318 def get_pool_attempts_per_second(tracker, previous_share_hash, net, dist=None):
 319     if dist is None:
 320         dist = net.TARGET_LOOKBEHIND
 321     near = tracker.shares[previous_share_hash]
 322     far = tracker.shares[tracker.get_nth_parent_hash(previous_share_hash, dist - 1)]
 323     attempts = tracker.get_work(near.hash) - tracker.get_work(far.hash)
 324     time = near.timestamp - far.timestamp
 325     if time == 0:
 326         time = 1
 327     return attempts//time
 328
 329 def generate_transaction(tracker, previous_share_hash, new_script, subsidy, nonce, block_target, net):
 330     height, last = tracker.get_height_and_last(previous_share_hash)
 331     assert height >= net.CHAIN_LENGTH or last is None
 332     if height < net.TARGET_LOOKBEHIND:
 333         target = bitcoin_data.FloatingInteger.from_target_upper_bound(net.MAX_TARGET)
 334     else:
 335         attempts_per_second = get_pool_attempts_per_second(tracker, previous_share_hash, net)
 336         previous_share = tracker.shares[previous_share_hash] if previous_share_hash is not None else None
 337         pre_target = 2**256//(net.SHARE_PERIOD*attempts_per_second) - 1
 338         pre_target2 = math.clip(pre_target, (previous_share.target*9//10, previous_share.target*11//10))
 339         pre_target3 = math.clip(pre_target2, (0, net.MAX_TARGET))
 340         target = bitcoin_data.FloatingInteger.from_target_upper_bound(pre_target3)
 341
 342     attempts_to_block = bitcoin_data.target_to_average_attempts(block_target)
 343     max_weight = 65535 * net.SPREAD * attempts_to_block
 344
 345     this_weight = 65535 * min(bitcoin_data.target_to_average_attempts(target), max_weight)
 346     other_weights, other_weights_total, other_donation_weight_total = tracker.get_cumulative_weights(previous_share_hash, min(height, net.CHAIN_LENGTH), max(0, max_weight - this_weight))
 347     dest_weights, total_weight, donation_weight_total = math.add_dicts([{new_script: this_weight}, other_weights]), this_weight + other_weights_total, other_donation_weight_total
 348     assert total_weight == sum(dest_weights.itervalues()) + donation_weight_total
 349
 350     if net.SCRIPT:
 351         amounts = dict((script, subsidy*(396*weight)//(400*total_weight)) for (script, weight) in dest_weights.iteritems())
 352         amounts[new_script] = amounts.get(new_script, 0) + subsidy*2//400
 353         amounts[net.SCRIPT] = amounts.get(net.SCRIPT, 0) + subsidy*2//400
 354         amounts[net.SCRIPT] = amounts.get(net.SCRIPT, 0) + subsidy - sum(amounts.itervalues()) # collect any extra
 355     else:
 356         amounts = dict((script, subsidy*(398*weight)//(400*total_weight)) for (script, weight) in dest_weights.iteritems())
 357         amounts[new_script] = amounts.get(new_script, 0) + subsidy*2//400
 358         amounts[new_script] = amounts.get(new_script, 0) + subsidy - sum(amounts.itervalues()) # collect any extra
 359
 360     if sum(amounts.itervalues()) != subsidy:
 361         raise ValueError()
 362     if any(x < 0 for x in amounts.itervalues()):
 363         raise ValueError()
 364
 365     pre_dests = sorted(amounts.iterkeys(), key=lambda script: (amounts[script], script))
 366     pre_dests = pre_dests[-4000:] # block length limit, unlikely to ever be hit
 367
 368     dests = sorted(pre_dests, key=lambda script: (script == new_script, script))
 369     assert dests[-1] == new_script
 370
 371     share_data = dict(
 372         previous_share_hash=previous_share_hash,
 373         nonce=nonce,
 374         target=target,
 375     )
 376
 377     share_info = dict(
 378         share_data=share_data,
 379         new_script=new_script,
 380         subsidy=subsidy,
 381     )
 382
 383     return share_info, dict(
 384         version=1,
 385         tx_ins=[dict(
 386             previous_output=None,
 387             sequence=None,
 388             script=coinbase_type.pack(dict(
 389                 identifier=net.IDENTIFIER,
 390                 share_data=share_data,
 391             )),
 392         )],
 393         tx_outs=[dict(value=amounts[script], script=script) for script in dests if amounts[script]],
 394         lock_time=0,
 395     )
 396
 397 def new_generate_transaction(tracker, new_share_data, block_target, net):
 398     previous_share_hash = new_share_data['previous_share_hash']
 399     new_script = new_share_data['new_script']
 400     subsidy = new_share_data['subsidy']
 401     donation = new_share_data['donation']
 402     assert 0 <= donation <= 65535
 403
 404     height, last = tracker.get_height_and_last(previous_share_hash)
 405     assert height >= net.CHAIN_LENGTH or last is None
 406     if height < net.TARGET_LOOKBEHIND:
 407         target = bitcoin_data.FloatingInteger.from_target_upper_bound(net.MAX_TARGET)
 408     else:
 409         attempts_per_second = get_pool_attempts_per_second(tracker, previous_share_hash, net)
 410         previous_share = tracker.shares[previous_share_hash] if previous_share_hash is not None else None
 411         pre_target = 2**256//(net.SHARE_PERIOD*attempts_per_second) - 1
 412         pre_target2 = math.clip(pre_target, (previous_share.target*9//10, previous_share.target*11//10))
 413         pre_target3 = math.clip(pre_target2, (0, net.MAX_TARGET))
 414         target = bitcoin_data.FloatingInteger.from_target_upper_bound(pre_target3)
 415
 416     attempts_to_block = bitcoin_data.target_to_average_attempts(block_target)
 417     max_att = net.SPREAD * attempts_to_block
 418
 419     this_att = min(bitcoin_data.target_to_average_attempts(target), max_att)
 420     other_weights, other_total_weight, other_donation_weight = tracker.get_cumulative_weights(previous_share_hash, min(height, net.CHAIN_LENGTH), 65535*max(0, max_att - this_att))
 421     assert other_total_weight == sum(other_weights.itervalues()) + other_donation_weight, (other_total_weight, sum(other_weights.itervalues()) + other_donation_weight)
 422     weights, total_weight, donation_weight = math.add_dicts([{new_script: this_att*(65535-donation)}, other_weights]), this_att*65535 + other_total_weight, this_att*donation + other_donation_weight
 423     assert total_weight == sum(weights.itervalues()) + donation_weight, (total_weight, sum(weights.itervalues()) + donation_weight)
 424
 425     amounts = dict((script, subsidy*(199*weight)//(200*total_weight)) for (script, weight) in weights.iteritems())
 426     amounts[new_script] = amounts.get(new_script, 0) + subsidy//200
 427     amounts[net.SCRIPT] = amounts.get(net.SCRIPT, 0) + subsidy*(199*donation_weight)//(200*total_weight)
 428     amounts[net.SCRIPT] = amounts.get(net.SCRIPT, 0) + subsidy - sum(amounts.itervalues()) # collect any extra satoshis :P
 429
 430     if sum(amounts.itervalues()) != subsidy:
 431         raise ValueError()
 432     if any(x < 0 for x in amounts.itervalues()):
 433         print amounts
 434         import code
 435         d = globals()
 436         d.update(locals())
 437         code.interact(local=d)
 438         raise ValueError()
 439
 440     pre_dests = sorted(amounts.iterkeys(), key=lambda script: (amounts[script], script))
 441     pre_dests = pre_dests[-4000:] # block length limit, unlikely to ever be hit
 442
 443     dests = sorted(pre_dests, key=lambda script: (script == new_script, script))
 444     assert dests[-1] == new_script
 445
 446     new_share_info = dict(
 447         new_share_data=new_share_data,
 448         target=target,
 449     )
 450
 451     return new_share_info, dict(
 452         version=1,
 453         tx_ins=[dict(
 454             previous_output=None,
 455             sequence=None,
 456             script=new_share_data['coinbase'],
 457         )],
 458         tx_outs=[dict(value=0, script=bitcoin_data.HashType().pack(new_share_info_type.hash256(new_share_info)))] + [dict(value=amounts[script], script=script) for script in dests if amounts[script]],
 459         lock_time=0,
 460     )
 461
 462
 463 class OkayTracker(bitcoin_data.Tracker):
 464     def __init__(self, net):
 465         bitcoin_data.Tracker.__init__(self)
 466         self.net = net
 467         self.verified = bitcoin_data.Tracker()
 468         self.verified.get_nth_parent_hash = self.get_nth_parent_hash # self is a superset of self.verified
 469
 470         self.get_cumulative_weights = skiplists.WeightsSkipList(self)
 471
 472     def add(self, share, known_verified=False):
 473         bitcoin_data.Tracker.add(self, share)
 474         if known_verified:
 475             self.verified.add(share)
 476
 477     def attempt_verify(self, share, now):
 478         if share.hash in self.verified.shares:
 479             return True
 480         height, last = self.get_height_and_last(share.hash)
 481         if height < self.net.CHAIN_LENGTH + 1 and last is not None:
 482             raise AssertionError()
 483         try:
 484             share.check(self, now, self.net)
 485         except:
 486             log.err(None, 'Share check failed:')
 487             return False
 488         else:
 489             self.verified.add(share)
 490             return True
 491
 492     def think(self, ht, previous_block, now):
 493         desired = set()
 494
 495         # O(len(self.heads))
 496         #   make 'unverified heads' set?
 497         # for each overall head, attempt verification
 498         # if it fails, attempt on parent, and repeat
 499         # if no successful verification because of lack of parents, request parent
 500         bads = set()
 501         for head in set(self.heads) - set(self.verified.heads):
 502             head_height, last = self.get_height_and_last(head)
 503
 504             for share in itertools.islice(self.get_chain_known(head), None if last is None else min(5, max(0, head_height - self.net.CHAIN_LENGTH))):
 505                 if self.attempt_verify(share, now):
 506                     break
 507                 if share.hash in self.heads:
 508                     bads.add(share.hash)
 509             else:
 510                 if last is not None:
 511                     desired.add((self.shares[random.choice(list(self.reverse_shares[last]))].peer, last))
 512         for bad in bads:
 513             assert bad not in self.verified.shares
 514             assert bad in self.heads
 515             if p2pool.DEBUG:
 516                 print "BAD", bad
 517             self.remove(bad)
 518
 519         # try to get at least CHAIN_LENGTH height for each verified head, requesting parents if needed
 520         for head in list(self.verified.heads):
 521             head_height, last_hash = self.verified.get_height_and_last(head)
 522             last_height, last_last_hash = self.get_height_and_last(last_hash)
 523             # XXX review boundary conditions
 524             want = max(self.net.CHAIN_LENGTH - head_height, 0)
 525             can = max(last_height - 1 - self.net.CHAIN_LENGTH, 0) if last_last_hash is not None else last_height
 526             get = min(want, can)
 527             #print 'Z', head_height, last_hash is None, last_height, last_last_hash is None, want, can, get
 528             for share in itertools.islice(self.get_chain_known(last_hash), get):
 529                 if not self.attempt_verify(share, now):
 530                     break
 531             if head_height < self.net.CHAIN_LENGTH and last_last_hash is not None:
 532                 desired.add((self.verified.shares[random.choice(list(self.verified.reverse_shares[last_hash]))].peer, last_last_hash))
 533
 534         # decide best tree
 535         best_tail = max(self.verified.tails, key=lambda h: self.score(max(self.verified.tails[h], key=self.verified.get_height), ht)) if self.verified.tails else None
 536         # decide best verified head
 537         scores = sorted(self.verified.tails.get(best_tail, []), key=lambda h: (
 538             self.verified.get_work(self.verified.get_nth_parent_hash(h, min(5, self.verified.get_height(h)))),
 539             #self.verified.shares[h].peer is None,
 540             ht.get_min_height(self.verified.shares[h].previous_block),
 541             -self.verified.shares[h].time_seen
 542         ))
 543
 544
 545         if p2pool.DEBUG:
 546             print len(self.verified.tails), "chain tails and", len(self.verified.tails.get(best_tail, [])), 'chain heads. Top 10 tails:'
 547             if len(scores) > 10:
 548                 print '    ...'
 549             for h in scores[-10:]:
 550                 print '   ', format_hash(h), format_hash(self.verified.shares[h].previous_hash), (
 551                     self.verified.get_work(self.verified.get_nth_parent_hash(h, min(5, self.verified.get_height(h)))),
 552                     self.verified.shares[h].peer is None,
 553                     ht.get_min_height(self.verified.shares[h].previous_block),
 554                     -self.verified.shares[h].time_seen
 555                 )
 556
 557         # eat away at heads
 558         if scores:
 559             for i in xrange(1000):
 560                 to_remove = set()
 561                 for share_hash, tail in self.heads.iteritems():
 562                     if share_hash in scores[-5:]:
 563                         #print 1
 564                         continue
 565                     if self.shares[share_hash].time_seen > time.time() - 300:
 566                         #print 2
 567                         continue
 568                     if share_hash not in self.verified.shares and max(self.shares[after_tail_hash].time_seen for after_tail_hash in self.reverse_shares.get(tail)) > time.time() - 120: # XXX stupid
 569                         #print 3
 570                         continue
 571                     to_remove.add(share_hash)
 572                 if not to_remove:
 573                     break
 574                 for share_hash in to_remove:
 575                     self.remove(share_hash)
 576                     if share_hash in self.verified.shares:
 577                         self.verified.remove(share_hash)
 578                 #print "_________", to_remove
 579
 580         # drop tails
 581         for i in xrange(1000):
 582             to_remove = set()
 583             for tail, heads in self.tails.iteritems():
 584                 if min(self.get_height(head) for head in heads) < 2*self.net.CHAIN_LENGTH + 10:
 585                     continue
 586                 for aftertail in self.reverse_shares.get(tail, set()):
 587                     if len(self.reverse_shares[self.shares[aftertail].previous_hash]) > 1: # XXX
 588                         print "raw"
 589                         continue
 590                     to_remove.add(aftertail)
 591             if not to_remove:
 592                 break
 593             # if removed from this, it must be removed from verified
 594             #start = time.time()
 595             for aftertail in to_remove:
 596                 if self.shares[aftertail].previous_hash not in self.tails:
 597                     print "erk", aftertail, self.shares[aftertail].previous_hash
 598                     continue
 599                 self.remove(aftertail)
 600                 if aftertail in self.verified.shares:
 601                     self.verified.remove(aftertail)
 602             #end = time.time()
 603             #print "removed! %i %f" % (len(to_remove), (end - start)/len(to_remove))
 604
 605         best = scores[-1] if scores else None
 606
 607         if best is not None:
 608             best_share = self.verified.shares[best]
 609             if ht.get_min_height(best_share.header['previous_block']) < ht.get_min_height(previous_block) and best_share.header_hash != previous_block and best_share.peer is not None:
 610                 if p2pool.DEBUG:
 611                     print 'Stale detected! %x < %x' % (best_share.header['previous_block'], previous_block)
 612                 best = best_share.previous_hash
 613
 614         return best, desired
 615
 616     @memoize.memoize_with_backing(expiring_dict.ExpiringDict(5, get_touches=False))
 617     def score(self, share_hash, ht):
 618         head_height, last = self.verified.get_height_and_last(share_hash)
 619         score2 = 0
 620         attempts = 0
 621         max_height = 0
 622         share2_hash = self.verified.get_nth_parent_hash(share_hash, min(self.net.CHAIN_LENGTH//2, head_height//2)) if last is not None else share_hash
 623         for share in reversed(list(itertools.islice(self.verified.get_chain_known(share2_hash), self.net.CHAIN_LENGTH))):
 624             max_height = max(max_height, ht.get_min_height(share.header['previous_block']))
 625             attempts += bitcoin_data.target_to_average_attempts(share.target)
 626             this_score = attempts//(ht.get_highest_height() - max_height + 1)
 627             if this_score > score2:
 628                 score2 = this_score
 629         return min(head_height, self.net.CHAIN_LENGTH), score2
 630
 631 def format_hash(x):
 632     if x is None:
 633         return 'xxxxxxxx'
 634     return '%08x' % (x % 2**32)
 635
 636 class ShareStore(object):
 637     def __init__(self, prefix, net):
 638         self.filename = prefix
 639         self.net = net
 640         self.known = None # will be filename -> set of share hashes, set of verified hashes
 641
 642     def get_shares(self):
 643         if self.known is not None:
 644             raise AssertionError()
 645         known = {}
 646         filenames, next = self.get_filenames_and_next()
 647         for filename in filenames:
 648             share_hashes, verified_hashes = known.setdefault(filename, (set(), set()))
 649             with open(filename, 'rb') as f:
 650                 for line in f:
 651                     try:
 652                         type_id_str, data_hex = line.strip().split(' ')
 653                         type_id = int(type_id_str)
 654                         if type_id == 0:
 655                             share = Share.from_share1a(share1a_type.unpack(data_hex.decode('hex')), self.net)
 656                             yield 'share', share
 657                             share_hashes.add(share.hash)
 658                         elif type_id == 1:
 659                             share = Share.from_share1b(share1b_type.unpack(data_hex.decode('hex')), self.net)
 660                             yield 'share', share
 661                             share_hashes.add(share.hash)
 662                         elif type_id == 2:
 663                             verified_hash = int(data_hex, 16)
 664                             yield 'verified_hash', verified_hash
 665                             verified_hashes.add(verified_hash)
 666                         elif type_id == 3:
 667                             share = NewShare.from_share1a(new_share1a_type.unpack(data_hex.decode('hex')), self.net)
 668                             yield 'share', share
 669                             share_hashes.add(share.hash)
 670                         elif type_id == 4:
 671                             share = NewShare.from_share1b(new_share1b_type.unpack(data_hex.decode('hex')), self.net)
 672                             yield 'share', share
 673                             share_hashes.add(share.hash)
 674                         else:
 675                             raise NotImplementedError("share type %i" % (type_id,))
 676                     except Exception:
 677                         log.err(None, "Error while reading saved shares, continuing where left off:")
 678         self.known = known
 679
 680     def _add_line(self, line):
 681         filenames, next = self.get_filenames_and_next()
 682         if filenames and os.path.getsize(filenames[-1]) < 10e6:
 683             filename = filenames[-1]
 684         else:
 685             filename = next
 686
 687         with open(filename, 'ab') as f:
 688             f.write(line + '\n')
 689
 690         return filename
 691
 692     def add_share(self, share):
 693         if isinstance(share, NewShare) and share.pow_hash <= share.header['target']:
 694             type_id, data = 4, new_share1b_type.pack(share.as_share1b())
 695         elif isinstance(share, NewShare):
 696             type_id, data = 3, new_share1a_type.pack(share.as_share1a())
 697         elif share.pow_hash <= share.header['target']:
 698             type_id, data = 1, share1b_type.pack(share.as_share1b())
 699         else:
 700             type_id, data = 0, share1a_type.pack(share.as_share1a())
 701         filename = self._add_line("%i %s" % (type_id, data.encode('hex')))
 702         share_hashes, verified_hashes = self.known.setdefault(filename, (set(), set()))
 703         share_hashes.add(share.hash)
 704
 705     def add_verified_hash(self, share_hash):
 706         filename = self._add_line("%i %x" % (2, share_hash))
 707         share_hashes, verified_hashes = self.known.setdefault(filename, (set(), set()))
 708         verified_hashes.add(share_hash)
 709
 710     def get_filenames_and_next(self):
 711         suffixes = sorted(int(x[len(self.filename):]) for x in os.listdir('.') if x.startswith(self.filename) and x[len(self.filename):].isdigit())
 712         return [self.filename + str(suffix) for suffix in suffixes], self.filename + str(suffixes[-1] + 1) if suffixes else self.filename + str(0)
 713
 714     def forget_share(self, share_hash):
 715         for filename, (share_hashes, verified_hashes) in self.known.iteritems():
 716             if share_hash in share_hashes:
 717                 share_hashes.remove(share_hash)
 718         self.check_remove()
 719
 720     def forget_verified_share(self, share_hash):
 721         for filename, (share_hashes, verified_hashes) in self.known.iteritems():
 722             if share_hash in verified_hashes:
 723                 verified_hashes.remove(share_hash)
 724         self.check_remove()
 725
 726     def check_remove(self):
 727         to_remove = set()
 728         for filename, (share_hashes, verified_hashes) in self.known.iteritems():
 729             #print filename, len(share_hashes) + len(verified_hashes)
 730             if not share_hashes and not verified_hashes:
 731                 to_remove.add(filename)
 732         for filename in to_remove:
 733             self.known.pop(filename)
 734             os.remove(filename)
 735             print "REMOVED", filename
 736
 737 class BitcoinMainnet(networks.BitcoinMainnet):
 738     SHARE_PERIOD = 10 # seconds
 739     CHAIN_LENGTH = 24*60*60//5 # shares
 740     TARGET_LOOKBEHIND = 200 # shares
 741     SPREAD = 3 # blocks
 742     SCRIPT = '4104ffd03de44a6e11b9917f3a29f9443283d9871c9d743ef30d5eddcd37094b64d1b3d8090496b53256786bf5c82932ec23c3b74d9f05a6f95a8b5529352656664bac'.decode('hex')
 743     IDENTIFIER = 'fc70035c7a81bc6f'.decode('hex')
 744     PREFIX = '2472ef181efcd37b'.decode('hex')
 745     NAME = 'bitcoin'
 746     P2P_PORT = 9333
 747     MAX_TARGET = 2**256//2**32 - 1
 748     PERSIST = False
 749     WORKER_PORT = 9332
 750
 751 class BitcoinTestnet(networks.BitcoinTestnet):
 752     SHARE_PERIOD = 1 # seconds
 753     CHAIN_LENGTH = 24*60*60//5 # shares
 754     TARGET_LOOKBEHIND = 200 # shares
 755     SPREAD = 3 # blocks
 756     SCRIPT = '410403ad3dee8ab3d8a9ce5dd2abfbe7364ccd9413df1d279bf1a207849310465b0956e5904b1155ecd17574778f9949589ebfd4fb33ce837c241474a225cf08d85dac'.decode('hex')
 757     IDENTIFIER = '5fc2be2d4f0d6bfb'.decode('hex')
 758     PREFIX = '3f6057a15036f441'.decode('hex')
 759     NAME = 'bitcoin_testnet'
 760     P2P_PORT = 19333
 761     MAX_TARGET = 2**256//2**32 - 1
 762     PERSIST = False
 763     WORKER_PORT = 19332
 764
 765 class NamecoinMainnet(networks.NamecoinMainnet):
 766     SHARE_PERIOD = 10 # seconds
 767     CHAIN_LENGTH = 24*60*60//10 # shares
 768     TARGET_LOOKBEHIND = 3600//10 # shares
 769     SPREAD = 3 # blocks
 770     SCRIPT = '41043da5beb73f8f18cede1a41b0ed953123f1342b8e0216ab5bf71ed3e024201b4017f472bddb6041f17978d89ed8f8ed84f9e726b0bca80cacf96347c7153e8df0ac'.decode('hex')
 771     IDENTIFIER = 'd5b1192062c4c454'.decode('hex')
 772     PREFIX = 'b56f3d0fb24fc982'.decode('hex')
 773     NAME = 'namecoin'
 774     P2P_PORT = 9334
 775     MAX_TARGET = 2**256//2**32 - 1
 776     PERSIST = True
 777     WORKER_PORT = 9331
 778
 779 class NamecoinTestnet(networks.NamecoinTestnet):
 780     SHARE_PERIOD = 1 # seconds
 781     CHAIN_LENGTH = 24*60*60//5 # shares
 782     TARGET_LOOKBEHIND = 200 # shares
 783     SPREAD = 3 # blocks
 784     SCRIPT = '410403ad3dee8ab3d8a9ce5dd2abfbe7364ccd9413df1d279bf1a207849310465b0956e5904b1155ecd17574778f9949589ebfd4fb33ce837c241474a225cf08d85dac'.decode('hex')
 785     IDENTIFIER = '8dd303d014a01a60'.decode('hex')
 786     PREFIX = '4d6581d24f51acbf'.decode('hex')
 787     NAME = 'namecoin_testnet'
 788     P2P_PORT = 19334
 789     MAX_TARGET = 2**256//2**20 - 1
 790     PERSIST = False
 791     WORKER_PORT = 19331
 792
 793 class IxcoinMainnet(networks.IxcoinMainnet):
 794     SHARE_PERIOD = 10 # seconds
 795     CHAIN_LENGTH = 24*60*60//10 # shares
 796     TARGET_LOOKBEHIND = 3600//10 # shares
 797     SPREAD = 3 # blocks
 798     SCRIPT = '41043da5beb73f8f18cede1a41b0ed953123f1342b8e0216ab5bf71ed3e024201b4017f472bddb6041f17978d89ed8f8ed84f9e726b0bca80cacf96347c7153e8df0ac'.decode('hex')
 799     IDENTIFIER = '27b564116e2a2666'.decode('hex')
 800     PREFIX = '9dd6c4a619401f2f'.decode('hex')
 801     NAME = 'ixcoin'
 802     P2P_PORT = 9335
 803     MAX_TARGET = 2**256//2**32 - 1
 804     PERSIST = True
 805     WORKER_PORT = 9330
 806
 807 class IxcoinTestnet(networks.IxcoinTestnet):
 808     SHARE_PERIOD = 1 # seconds
 809     CHAIN_LENGTH = 24*60*60//5 # shares
 810     TARGET_LOOKBEHIND = 200 # shares
 811     SPREAD = 3 # blocks
 812     SCRIPT = '410403ad3dee8ab3d8a9ce5dd2abfbe7364ccd9413df1d279bf1a207849310465b0956e5904b1155ecd17574778f9949589ebfd4fb33ce837c241474a225cf08d85dac'.decode('hex')
 813     IDENTIFIER = '7430cbeb01249e44'.decode('hex')
 814     PREFIX = '7cfffda946709c1f'.decode('hex')
 815     NAME = 'ixcoin_testnet'
 816     P2P_PORT = 19335
 817     MAX_TARGET = 2**256//2**20 - 1
 818     PERSIST = False
 819     WORKER_PORT = 19330
 820
 821 class I0coinMainnet(networks.I0coinMainnet):
 822     SHARE_PERIOD = 10 # seconds
 823     CHAIN_LENGTH = 24*60*60//10 # shares
 824     TARGET_LOOKBEHIND = 3600//10 # shares
 825     SPREAD = 3 # blocks
 826     SCRIPT = '410403ad3dee8ab3d8a9ce5dd2abfbe7364ccd9413df1d279bf1a207849310465b0956e5904b1155ecd17574778f9949589ebfd4fb33ce837c241474a225cf08d85dac'.decode('hex')
 827     IDENTIFIER = 'b32e3f10c2ff221b'.decode('hex')
 828     PREFIX = '6155537ed977a3b5'.decode('hex')
 829     NAME = 'i0coin'
 830     P2P_PORT = 9336
 831     MAX_TARGET = 2**256//2**32 - 1
 832     PERSIST = False
 833     WORKER_PORT = 9329
 834
 835 class I0coinTestnet(networks.I0coinTestnet):
 836     SHARE_PERIOD = 1 # seconds
 837     CHAIN_LENGTH = 24*60*60//5 # shares
 838     TARGET_LOOKBEHIND = 200 # shares
 839     SPREAD = 3 # blocks
 840     SCRIPT = '410403ad3dee8ab3d8a9ce5dd2abfbe7364ccd9413df1d279bf1a207849310465b0956e5904b1155ecd17574778f9949589ebfd4fb33ce837c241474a225cf08d85dac'.decode('hex')
 841     IDENTIFIER = '7712c1a8181b5f2e'.decode('hex')
 842     PREFIX = '792d2e7d770fbe68'.decode('hex')
 843     NAME = 'i0coin_testnet'
 844     P2P_PORT = 19336
 845     MAX_TARGET = 2**256//2**20 - 1
 846     PERSIST = False
 847     WORKER_PORT = 19329
 848
 849 class SolidcoinMainnet(networks.SolidcoinMainnet):
 850     SHARE_PERIOD = 10
 851     CHAIN_LENGTH = 24*60*60//10 # shares
 852     TARGET_LOOKBEHIND = 3600//10 # shares
 853     SPREAD = 3 # blocks
 854     SCRIPT = bitcoin_data.pubkey_hash_to_script2(bitcoin_data.address_to_pubkey_hash('sMKZ1yxHETxPYKh4Z2anWnwZDJZU7ztroy', networks.SolidcoinMainnet))
 855     IDENTIFIER = '9cc9c421cca258cd'.decode('hex')
 856     PREFIX = 'c059125b8070f00a'.decode('hex')
 857     NAME = 'solidcoin'
 858     P2P_PORT = 9337
 859     MAX_TARGET = 2**256//2**32 - 1
 860     PERSIST = True
 861     WORKER_PORT = 9328
 862
 863 class LitecoinMainnet(networks.LitecoinMainnet):
 864     SHARE_PERIOD = 10 # seconds
 865     CHAIN_LENGTH = 24*60*60//5 # shares
 866     TARGET_LOOKBEHIND = 200 # shares
 867     SPREAD = 12 # blocks
 868     SCRIPT = None # no fee
 869     IDENTIFIER = 'e037d5b8c6923410'.decode('hex')
 870     PREFIX = '7208c1a53ef629b0'.decode('hex')
 871     NAME = 'litecoin'
 872     P2P_PORT = 9338
 873     MAX_TARGET = 2**256//2**20 - 1
 874     PERSIST = True
 875     WORKER_PORT = 9327
 876
 877 class LitecoinTestnet(networks.LitecoinTestnet):
 878     SHARE_PERIOD = 1 # seconds
 879     CHAIN_LENGTH = 24*60*60//5 # shares
 880     TARGET_LOOKBEHIND = 200 # shares
 881     SPREAD = 12 # blocks
 882     SCRIPT = None # no fee
 883     IDENTIFIER = 'cca5e24ec6408b1e'.decode('hex')
 884     PREFIX = 'ad9614f6466a39cf'.decode('hex')
 885     NAME = 'litecoin_testnet'
 886     P2P_PORT = 19338
 887     MAX_TARGET = 2**256//2**17 - 1
 888     PERSIST = False
 889     WORKER_PORT = 19327
 890
 891 nets = dict((net.NAME, net) for net in set([BitcoinMainnet, BitcoinTestnet, NamecoinMainnet, NamecoinTestnet, IxcoinMainnet, IxcoinTestnet, I0coinMainnet, I0coinTestnet, SolidcoinMainnet, LitecoinMainnet, LitecoinTestnet]))