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, namecoin, ixcoin, i0coin, solidcoin, litecoin
  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_block(cls, block, net):
 123         return cls(net, block['header'], gentx_to_share_info(block['txs'][0]), other_txs=block['txs'][1:])
 124
 125     @classmethod
 126     def from_share1a(cls, share1a, net):
 127         return cls(net, **share1a)
 128
 129     @classmethod
 130     def from_share1b(cls, share1b, net):
 131         return cls(net, **share1b)
 132
 133     __slots__ = 'header previous_block share_info merkle_branch other_txs timestamp share_data new_script subsidy previous_hash previous_share_hash target nonce bitcoin_hash hash time_seen shared stored peer'.split(' ')
 134
 135     def __init__(self, net, header, share_info, merkle_branch=None, other_txs=None):
 136         if merkle_branch is None and other_txs is None:
 137             raise ValueError('need either merkle_branch or other_txs')
 138         if other_txs is not None:
 139             new_merkle_branch = calculate_merkle_branch([dict(version=0, tx_ins=[], tx_outs=[], lock_time=0)] + other_txs, 0)
 140             if merkle_branch is not None:
 141                 if merke_branch != new_merkle_branch:
 142                     raise ValueError('invalid merkle_branch and other_txs')
 143             merkle_branch = new_merkle_branch
 144
 145         if len(merkle_branch) > 16:
 146             raise ValueError('merkle_branch too long!')
 147
 148         self.header = header
 149         self.previous_block = header['previous_block']
 150         self.share_info = share_info
 151         self.merkle_branch = merkle_branch
 152         self.other_txs = other_txs
 153
 154         self.timestamp = self.header['timestamp']
 155
 156         self.share_data = self.share_info['share_data']
 157         self.new_script = self.share_info['new_script']
 158         self.subsidy = self.share_info['subsidy']
 159
 160         if len(self.new_script) > 100:
 161             raise ValueError('new_script too long!')
 162
 163         self.previous_hash = self.previous_share_hash = self.share_data['previous_share_hash']
 164         self.target = self.share_data['target']
 165         self.nonce = self.share_data['nonce']
 166
 167         if len(self.nonce) > 100:
 168             raise ValueError('nonce too long!')
 169
 170         # use scrypt for Litecoin
 171         if (getattr(net, 'BITCOIN_POW_SCRYPT', False)):
 172             self.bitcoin_hash = bitcoin_data.block_header_type.scrypt(header)
 173             self.hash = share1a_type.scrypt(self.as_share1a())
 174         else:
 175             self.bitcoin_hash = bitcoin_data.block_header_type.hash256(header)
 176             self.hash = share1a_type.hash256(self.as_share1a())
 177
 178         if self.bitcoin_hash > self.target:
 179             print 'hash %x' % self.bitcoin_hash
 180             print 'targ %x' % self.target
 181             raise ValueError('not enough work!')
 182
 183         if script.get_sigop_count(self.new_script) > 1:
 184             raise ValueError('too many sigops!')
 185
 186         # XXX eww
 187         self.time_seen = time.time()
 188         self.shared = False
 189         self.stored = False
 190         self.peer = None
 191
 192     def as_block(self, tracker, net):
 193         if self.other_txs is None:
 194             raise ValueError('share does not contain all txs')
 195
 196         gentx = share_info_to_gentx(self.share_info, self.header['target'], tracker, net)
 197
 198         return dict(header=self.header, txs=[gentx] + self.other_txs)
 199
 200     def as_share1a(self):
 201         return dict(header=self.header, share_info=self.share_info, merkle_branch=self.merkle_branch)
 202
 203     def as_share1b(self):
 204         if self.other_txs is None:
 205             raise ValueError('share does not contain all txs')
 206
 207         return dict(header=self.header, share_info=self.share_info, other_txs=self.other_txs)
 208
 209     def check(self, tracker, now, net):
 210         import time
 211         if self.previous_share_hash is not None:
 212             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):
 213                 raise ValueError('share from too far in the past!')
 214
 215         if self.header['timestamp'] > now + 2*60*60:
 216             raise ValueError('share from too far in the future!')
 217
 218         gentx = share_info_to_gentx(self.share_info, self.header['target'], tracker, net)
 219
 220         if len(gentx['tx_ins'][0]['script']) > 100:
 221             raise ValueError('''coinbase too large! %i bytes''' % (len(gentx['tx_ins'][0]['script']),))
 222
 223         if check_merkle_branch(gentx, self.merkle_branch) != self.header['merkle_root']:
 224             raise ValueError('''gentx doesn't match header via merkle_branch''')
 225
 226         if self.other_txs is not None:
 227             if bitcoin_data.merkle_hash([gentx] + self.other_txs) != self.header['merkle_root']:
 228                 raise ValueError('''gentx doesn't match header via other_txs''')
 229
 230             if len(bitcoin_data.block_type.pack(dict(header=self.header, txs=[gentx] + self.other_txs))) > 1000000 - 1000:
 231                 raise ValueError('''block size too large''')
 232
 233     def flag_shared(self):
 234         self.shared = True
 235
 236     def __repr__(self):
 237         return '<Share %s>' % (' '.join('%s=%r' % (k, getattr(self, k)) for k in self.__slots__),)
 238
 239 class NewShare(Share):
 240     def __init__(self, net, header, new_share_info, merkle_branch=None, other_txs=None):
 241         if merkle_branch is None and other_txs is None:
 242             raise ValueError('need either merkle_branch or other_txs')
 243         if other_txs is not None:
 244             new_merkle_branch = bitcoin_data.calculate_merkle_branch([dict(version=0, tx_ins=[], tx_outs=[], lock_time=0)] + other_txs, 0)
 245             if merkle_branch is not None:
 246                 if merke_branch != new_merkle_branch:
 247                     raise ValueError('invalid merkle_branch and other_txs')
 248             merkle_branch = new_merkle_branch
 249
 250         if len(merkle_branch) > 16:
 251             raise ValueError('merkle_branch too long!')
 252
 253         self.header = header
 254         self.previous_block = header['previous_block']
 255         self.share_info = new_share_info
 256         self.merkle_branch = merkle_branch
 257         self.other_txs = other_txs
 258
 259         self.timestamp = self.header['timestamp']
 260
 261         self.share_data = self.share_info['new_share_data']
 262         self.new_script = self.share_data['new_script']
 263         self.subsidy = self.share_data['subsidy']
 264
 265         if len(self.new_script) > 100:
 266             raise ValueError('new_script too long!')
 267
 268         self.previous_hash = self.previous_share_hash = self.share_data['previous_share_hash']
 269         self.target = self.share_info['target']
 270         self.nonce = self.share_data['nonce']
 271
 272         if len(self.nonce) > 100:
 273             raise ValueError('nonce too long!')
 274
 275         if getattr(net, 'BITCOIN_POW_SCRYPT', False):
 276             self.bitcoin_hash = bitcoin_data.block_header_type.scrypt(header)
 277         else:
 278             self.bitcoin_hash = bitcoin_data.block_header_type.hash256(header)
 279
 280         self.hash = new_share1a_type.hash256(self.as_share1a())
 281
 282         if self.bitcoin_hash > self.target:
 283             print 'hash %x' % self.bitcoin_hash
 284             print 'targ %x' % self.target
 285             raise ValueError('not enough work!')
 286
 287         if script.get_sigop_count(self.new_script) > 1:
 288             raise ValueError('too many sigops!')
 289
 290         # XXX eww
 291         self.time_seen = time.time()
 292         self.shared = False
 293         self.stored = False
 294         self.peer = None
 295
 296     def check(self, tracker, now, net):
 297         import time
 298         if self.previous_share_hash is not None:
 299             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):
 300                 raise ValueError('share from too far in the past!')
 301
 302         if self.header['timestamp'] > now + 2*60*60:
 303             raise ValueError('share from too far in the future!')
 304
 305         new_share_info, gentx = new_generate_transaction(tracker, self.share_info['new_share_data'], self.header['target'], net)
 306         if new_share_info != self.share_info:
 307             raise ValueError()
 308
 309         if len(gentx['tx_ins'][0]['script']) > 100:
 310             raise ValueError('''coinbase too large! %i bytes''' % (len(gentx['tx_ins'][0]['script']),))
 311
 312         if bitcoin_data.check_merkle_branch(gentx, 0, self.merkle_branch) != self.header['merkle_root']:
 313             raise ValueError('''gentx doesn't match header via merkle_branch''')
 314
 315         if self.other_txs is not None:
 316             if bitcoin_data.merkle_hash([gentx] + self.other_txs) != self.header['merkle_root']:
 317                 raise ValueError('''gentx doesn't match header via other_txs''')
 318
 319             if len(bitcoin_data.block_type.pack(dict(header=self.header, txs=[gentx] + self.other_txs))) > 1000000 - 1000:
 320                 raise ValueError('''block size too large''')
 321
 322 def get_pool_attempts_per_second(tracker, previous_share_hash, net, dist=None):
 323     if dist is None:
 324         dist = net.TARGET_LOOKBEHIND
 325     near = tracker.shares[previous_share_hash]
 326     far = tracker.shares[tracker.get_nth_parent_hash(previous_share_hash, dist - 1)]
 327     attempts = tracker.get_work(near.hash) - tracker.get_work(far.hash)
 328     time = near.timestamp - far.timestamp
 329     if time == 0:
 330         time = 1
 331     return attempts//time
 332
 333 def generate_transaction(tracker, previous_share_hash, new_script, subsidy, nonce, block_target, net):
 334     height, last = tracker.get_height_and_last(previous_share_hash)
 335     assert height >= net.CHAIN_LENGTH or last is None
 336     if height < net.TARGET_LOOKBEHIND:
 337         target = bitcoin_data.FloatingInteger.from_target_upper_bound(net.MAX_TARGET)
 338     else:
 339         attempts_per_second = get_pool_attempts_per_second(tracker, previous_share_hash, net)
 340         previous_share = tracker.shares[previous_share_hash] if previous_share_hash is not None else None
 341         pre_target = 2**256//(net.SHARE_PERIOD*attempts_per_second) - 1
 342         pre_target2 = math.clip(pre_target, (previous_share.target*9//10, previous_share.target*11//10))
 343         pre_target3 = math.clip(pre_target2, (0, net.MAX_TARGET))
 344         target = bitcoin_data.FloatingInteger.from_target_upper_bound(pre_target3)
 345
 346     attempts_to_block = bitcoin_data.target_to_average_attempts(block_target)
 347     max_weight = 65535 * net.SPREAD * attempts_to_block
 348
 349     this_weight = 65535 * min(bitcoin_data.target_to_average_attempts(target), max_weight)
 350     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))
 351     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
 352     assert total_weight == sum(dest_weights.itervalues()) + donation_weight_total
 353
 354     if net.SCRIPT:
 355         amounts = dict((script, subsidy*(396*weight)//(400*total_weight)) for (script, weight) in dest_weights.iteritems())
 356         amounts[new_script] = amounts.get(new_script, 0) + subsidy*2//400
 357         amounts[net.SCRIPT] = amounts.get(net.SCRIPT, 0) + subsidy*2//400
 358         amounts[net.SCRIPT] = amounts.get(net.SCRIPT, 0) + subsidy - sum(amounts.itervalues()) # collect any extra
 359     else:
 360         amounts = dict((script, subsidy*(398*weight)//(400*total_weight)) for (script, weight) in dest_weights.iteritems())
 361         amounts[new_script] = amounts.get(new_script, 0) + subsidy*2//400
 362         amounts[new_script] = amounts.get(new_script, 0) + subsidy - sum(amounts.itervalues()) # collect any extra
 363
 364     if sum(amounts.itervalues()) != subsidy:
 365         raise ValueError()
 366     if any(x < 0 for x in amounts.itervalues()):
 367         raise ValueError()
 368
 369     pre_dests = sorted(amounts.iterkeys(), key=lambda script: (amounts[script], script))
 370     pre_dests = pre_dests[-4000:] # block length limit, unlikely to ever be hit
 371
 372     dests = sorted(pre_dests, key=lambda script: (script == new_script, script))
 373     assert dests[-1] == new_script
 374
 375     share_data = dict(
 376         previous_share_hash=previous_share_hash,
 377         nonce=nonce,
 378         target=target,
 379     )
 380
 381     share_info = dict(
 382         share_data=share_data,
 383         new_script=new_script,
 384         subsidy=subsidy,
 385     )
 386
 387     return share_info, dict(
 388         version=1,
 389         tx_ins=[dict(
 390             previous_output=None,
 391             sequence=None,
 392             script=coinbase_type.pack(dict(
 393                 identifier=net.IDENTIFIER,
 394                 share_data=share_data,
 395             )),
 396         )],
 397         tx_outs=[dict(value=amounts[script], script=script) for script in dests if amounts[script]],
 398         lock_time=0,
 399     )
 400
 401 def new_generate_transaction(tracker, new_share_data, block_target, net):
 402     previous_share_hash = new_share_data['previous_share_hash']
 403     new_script = new_share_data['new_script']
 404     subsidy = new_share_data['subsidy']
 405     donation = new_share_data['donation']
 406     assert 0 <= donation <= 65535
 407
 408     height, last = tracker.get_height_and_last(previous_share_hash)
 409     assert height >= net.CHAIN_LENGTH or last is None
 410     if height < net.TARGET_LOOKBEHIND:
 411         target = bitcoin_data.FloatingInteger.from_target_upper_bound(net.MAX_TARGET)
 412     else:
 413         attempts_per_second = get_pool_attempts_per_second(tracker, previous_share_hash, net)
 414         previous_share = tracker.shares[previous_share_hash] if previous_share_hash is not None else None
 415         pre_target = 2**256//(net.SHARE_PERIOD*attempts_per_second) - 1
 416         pre_target2 = math.clip(pre_target, (previous_share.target*9//10, previous_share.target*11//10))
 417         pre_target3 = math.clip(pre_target2, (0, net.MAX_TARGET))
 418         target = bitcoin_data.FloatingInteger.from_target_upper_bound(pre_target3)
 419
 420     attempts_to_block = bitcoin_data.target_to_average_attempts(block_target)
 421     max_att = net.SPREAD * attempts_to_block
 422
 423     this_att = min(bitcoin_data.target_to_average_attempts(target), max_att)
 424     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))
 425     assert other_total_weight == sum(other_weights.itervalues()) + other_donation_weight, (other_total_weight, sum(other_weights.itervalues()) + other_donation_weight)
 426     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
 427     assert total_weight == sum(weights.itervalues()) + donation_weight, (total_weight, sum(weights.itervalues()) + donation_weight)
 428
 429     amounts = dict((script, subsidy*(199*weight)//(200*total_weight)) for (script, weight) in weights.iteritems())
 430     amounts[new_script] = amounts.get(new_script, 0) + subsidy//200
 431     amounts[net.SCRIPT] = amounts.get(net.SCRIPT, 0) + subsidy*(199*donation_weight)//(200*total_weight)
 432     amounts[net.SCRIPT] = amounts.get(net.SCRIPT, 0) + subsidy - sum(amounts.itervalues()) # collect any extra satoshis :P
 433
 434     if sum(amounts.itervalues()) != subsidy:
 435         raise ValueError()
 436     if any(x < 0 for x in amounts.itervalues()):
 437         print amounts
 438         import code
 439         d = globals()
 440         d.update(locals())
 441         code.interact(local=d)
 442         raise ValueError()
 443
 444     pre_dests = sorted(amounts.iterkeys(), key=lambda script: (amounts[script], script))
 445     pre_dests = pre_dests[-4000:] # block length limit, unlikely to ever be hit
 446
 447     dests = sorted(pre_dests, key=lambda script: (script == new_script, script))
 448     assert dests[-1] == new_script
 449
 450     new_share_info = dict(
 451         new_share_data=new_share_data,
 452         target=target,
 453     )
 454
 455     return new_share_info, dict(
 456         version=1,
 457         tx_ins=[dict(
 458             previous_output=None,
 459             sequence=None,
 460             script=new_share_data['coinbase'],
 461         )],
 462         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]],
 463         lock_time=0,
 464     )
 465
 466
 467 class OkayTracker(bitcoin_data.Tracker):
 468     def __init__(self, net):
 469         bitcoin_data.Tracker.__init__(self)
 470         self.net = net
 471         self.verified = bitcoin_data.Tracker()
 472         self.verified.get_nth_parent_hash = self.get_nth_parent_hash # self is a superset of self.verified
 473
 474         self.get_cumulative_weights = skiplists.WeightsSkipList(self)
 475
 476     def add(self, share, known_verified=False):
 477         bitcoin_data.Tracker.add(self, share)
 478         if known_verified:
 479             self.verified.add(share)
 480
 481     def attempt_verify(self, share, now):
 482         if share.hash in self.verified.shares:
 483             return True
 484         height, last = self.get_height_and_last(share.hash)
 485         if height < self.net.CHAIN_LENGTH + 1 and last is not None:
 486             raise AssertionError()
 487         try:
 488             share.check(self, now, self.net)
 489         except:
 490             log.err(None, 'Share check failed:')
 491             return False
 492         else:
 493             self.verified.add(share)
 494             return True
 495
 496     def think(self, ht, previous_block, now):
 497         desired = set()
 498
 499         # O(len(self.heads))
 500         #   make 'unverified heads' set?
 501         # for each overall head, attempt verification
 502         # if it fails, attempt on parent, and repeat
 503         # if no successful verification because of lack of parents, request parent
 504         bads = set()
 505         for head in set(self.heads) - set(self.verified.heads):
 506             head_height, last = self.get_height_and_last(head)
 507
 508             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))):
 509                 if self.attempt_verify(share, now):
 510                     break
 511                 if share.hash in self.heads:
 512                     bads.add(share.hash)
 513             else:
 514                 if last is not None:
 515                     desired.add((self.shares[random.choice(list(self.reverse_shares[last]))].peer, last))
 516         for bad in bads:
 517             assert bad not in self.verified.shares
 518             assert bad in self.heads
 519             if p2pool.DEBUG:
 520                 print "BAD", bad
 521             self.remove(bad)
 522
 523         # try to get at least CHAIN_LENGTH height for each verified head, requesting parents if needed
 524         for head in list(self.verified.heads):
 525             head_height, last_hash = self.verified.get_height_and_last(head)
 526             last_height, last_last_hash = self.get_height_and_last(last_hash)
 527             # XXX review boundary conditions
 528             want = max(self.net.CHAIN_LENGTH - head_height, 0)
 529             can = max(last_height - 1 - self.net.CHAIN_LENGTH, 0) if last_last_hash is not None else last_height
 530             get = min(want, can)
 531             #print 'Z', head_height, last_hash is None, last_height, last_last_hash is None, want, can, get
 532             for share in itertools.islice(self.get_chain_known(last_hash), get):
 533                 if not self.attempt_verify(share, now):
 534                     break
 535             if head_height < self.net.CHAIN_LENGTH and last_last_hash is not None:
 536                 desired.add((self.verified.shares[random.choice(list(self.verified.reverse_shares[last_hash]))].peer, last_last_hash))
 537
 538         # decide best tree
 539         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
 540         # decide best verified head
 541         scores = sorted(self.verified.tails.get(best_tail, []), key=lambda h: (
 542             self.verified.get_work(self.verified.get_nth_parent_hash(h, min(5, self.verified.get_height(h)))),
 543             #self.verified.shares[h].peer is None,
 544             ht.get_min_height(self.verified.shares[h].previous_block),
 545             -self.verified.shares[h].time_seen
 546         ))
 547
 548
 549         if p2pool.DEBUG:
 550             print len(self.verified.tails), "chain tails and", len(self.verified.tails.get(best_tail, [])), 'chain heads. Top 10 tails:'
 551             if len(scores) > 10:
 552                 print '    ...'
 553             for h in scores[-10:]:
 554                 print '   ', format_hash(h), format_hash(self.verified.shares[h].previous_hash), (
 555                     self.verified.get_work(self.verified.get_nth_parent_hash(h, min(5, self.verified.get_height(h)))),
 556                     self.verified.shares[h].peer is None,
 557                     ht.get_min_height(self.verified.shares[h].previous_block),
 558                     -self.verified.shares[h].time_seen
 559                 )
 560
 561         # eat away at heads
 562         if scores:
 563             for i in xrange(1000):
 564                 to_remove = set()
 565                 for share_hash, tail in self.heads.iteritems():
 566                     if share_hash in scores[-5:]:
 567                         #print 1
 568                         continue
 569                     if self.shares[share_hash].time_seen > time.time() - 300:
 570                         #print 2
 571                         continue
 572                     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
 573                         #print 3
 574                         continue
 575                     to_remove.add(share_hash)
 576                 if not to_remove:
 577                     break
 578                 for share_hash in to_remove:
 579                     self.remove(share_hash)
 580                     if share_hash in self.verified.shares:
 581                         self.verified.remove(share_hash)
 582                 #print "_________", to_remove
 583
 584         # drop tails
 585         for i in xrange(1000):
 586             to_remove = set()
 587             for tail, heads in self.tails.iteritems():
 588                 if min(self.get_height(head) for head in heads) < 2*self.net.CHAIN_LENGTH + 10:
 589                     continue
 590                 for aftertail in self.reverse_shares.get(tail, set()):
 591                     if len(self.reverse_shares[self.shares[aftertail].previous_hash]) > 1: # XXX
 592                         print "raw"
 593                         continue
 594                     to_remove.add(aftertail)
 595             if not to_remove:
 596                 break
 597             # if removed from this, it must be removed from verified
 598             #start = time.time()
 599             for aftertail in to_remove:
 600                 if self.shares[aftertail].previous_hash not in self.tails:
 601                     print "erk", aftertail, self.shares[aftertail].previous_hash
 602                     continue
 603                 self.remove(aftertail)
 604                 if aftertail in self.verified.shares:
 605                     self.verified.remove(aftertail)
 606             #end = time.time()
 607             #print "removed! %i %f" % (len(to_remove), (end - start)/len(to_remove))
 608
 609         best = scores[-1] if scores else None
 610
 611         if best is not None:
 612             best_share = self.verified.shares[best]
 613             if ht.get_min_height(best_share.header['previous_block']) < ht.get_min_height(previous_block) and best_share.bitcoin_hash != previous_block and best_share.peer is not None:
 614                 if p2pool.DEBUG:
 615                     print 'Stale detected! %x < %x' % (best_share.header['previous_block'], previous_block)
 616                 best = best_share.previous_hash
 617
 618         return best, desired
 619
 620     @memoize.memoize_with_backing(expiring_dict.ExpiringDict(5, get_touches=False))
 621     def score(self, share_hash, ht):
 622         head_height, last = self.verified.get_height_and_last(share_hash)
 623         score2 = 0
 624         attempts = 0
 625         max_height = 0
 626         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
 627         for share in reversed(list(itertools.islice(self.verified.get_chain_known(share2_hash), self.net.CHAIN_LENGTH))):
 628             max_height = max(max_height, ht.get_min_height(share.header['previous_block']))
 629             attempts += bitcoin_data.target_to_average_attempts(share.target)
 630             this_score = attempts//(ht.get_highest_height() - max_height + 1)
 631             if this_score > score2:
 632                 score2 = this_score
 633         return min(head_height, self.net.CHAIN_LENGTH), score2
 634
 635 def format_hash(x):
 636     if x is None:
 637         return 'xxxxxxxx'
 638     return '%08x' % (x % 2**32)
 639
 640 class ShareStore(object):
 641     def __init__(self, prefix, net):
 642         self.filename = prefix
 643         self.net = net
 644         self.known = None # will be filename -> set of share hashes, set of verified hashes
 645
 646     def get_shares(self):
 647         if self.known is not None:
 648             raise AssertionError()
 649         known = {}
 650         filenames, next = self.get_filenames_and_next()
 651         for filename in filenames:
 652             share_hashes, verified_hashes = known.setdefault(filename, (set(), set()))
 653             with open(filename, 'rb') as f:
 654                 for line in f:
 655                     try:
 656                         type_id_str, data_hex = line.strip().split(' ')
 657                         type_id = int(type_id_str)
 658                         if type_id == 0:
 659                             share = Share.from_share1a(share1a_type.unpack(data_hex.decode('hex')), self.net)
 660                             yield 'share', share
 661                             share_hashes.add(share.hash)
 662                         elif type_id == 1:
 663                             share = Share.from_share1b(share1b_type.unpack(data_hex.decode('hex')), self.net)
 664                             yield 'share', share
 665                             share_hashes.add(share.hash)
 666                         elif type_id == 2:
 667                             verified_hash = int(data_hex, 16)
 668                             yield 'verified_hash', verified_hash
 669                             verified_hashes.add(verified_hash)
 670                         elif type_id == 3:
 671                             share = NewShare.from_share1a(new_share1a_type.unpack(data_hex.decode('hex')), self.net)
 672                             yield 'share', share
 673                             share_hashes.add(share.hash)
 674                         elif type_id == 4:
 675                             share = NewShare.from_share1b(new_share1b_type.unpack(data_hex.decode('hex')), self.net)
 676                             yield 'share', share
 677                             share_hashes.add(share.hash)
 678                         else:
 679                             raise NotImplementedError("share type %i" % (type_id,))
 680                     except Exception:
 681                         log.err(None, "Error while reading saved shares, continuing where left off:")
 682         self.known = known
 683
 684     def _add_line(self, line):
 685         filenames, next = self.get_filenames_and_next()
 686         if filenames and os.path.getsize(filenames[-1]) < 10e6:
 687             filename = filenames[-1]
 688         else:
 689             filename = next
 690
 691         with open(filename, 'ab') as f:
 692             f.write(line + '\n')
 693
 694         return filename
 695
 696     def add_share(self, share):
 697         if isinstance(share, NewShare) and share.bitcoin_hash <= share.header['target']:
 698             type_id, data = 4, new_share1b_type.pack(share.as_share1b())
 699         elif isinstance(share, NewShare):
 700             type_id, data = 3, new_share1a_type.pack(share.as_share1a())
 701         elif share.bitcoin_hash <= share.header['target']:
 702             type_id, data = 1, share1b_type.pack(share.as_share1b())
 703         else:
 704             type_id, data = 0, share1a_type.pack(share.as_share1a())
 705         filename = self._add_line("%i %s" % (type_id, data.encode('hex')))
 706         share_hashes, verified_hashes = self.known.setdefault(filename, (set(), set()))
 707         share_hashes.add(share.hash)
 708
 709     def add_verified_hash(self, share_hash):
 710         filename = self._add_line("%i %x" % (2, share_hash))
 711         share_hashes, verified_hashes = self.known.setdefault(filename, (set(), set()))
 712         verified_hashes.add(share_hash)
 713
 714     def get_filenames_and_next(self):
 715         suffixes = sorted(int(x[len(self.filename):]) for x in os.listdir('.') if x.startswith(self.filename) and x[len(self.filename):].isdigit())
 716         return [self.filename + str(suffix) for suffix in suffixes], self.filename + str(suffixes[-1] + 1) if suffixes else self.filename + str(0)
 717
 718     def forget_share(self, share_hash):
 719         for filename, (share_hashes, verified_hashes) in self.known.iteritems():
 720             if share_hash in share_hashes:
 721                 share_hashes.remove(share_hash)
 722         self.check_remove()
 723
 724     def forget_verified_share(self, share_hash):
 725         for filename, (share_hashes, verified_hashes) in self.known.iteritems():
 726             if share_hash in verified_hashes:
 727                 verified_hashes.remove(share_hash)
 728         self.check_remove()
 729
 730     def check_remove(self):
 731         to_remove = set()
 732         for filename, (share_hashes, verified_hashes) in self.known.iteritems():
 733             #print filename, len(share_hashes) + len(verified_hashes)
 734             if not share_hashes and not verified_hashes:
 735                 to_remove.add(filename)
 736         for filename in to_remove:
 737             self.known.pop(filename)
 738             os.remove(filename)
 739             print "REMOVED", filename
 740
 741 class BitcoinMainnet(bitcoin_data.Mainnet):
 742     SHARE_PERIOD = 10 # seconds
 743     CHAIN_LENGTH = 24*60*60//5 # shares
 744     TARGET_LOOKBEHIND = 200 # shares
 745     SPREAD = 3 # blocks
 746     SCRIPT = '4104ffd03de44a6e11b9917f3a29f9443283d9871c9d743ef30d5eddcd37094b64d1b3d8090496b53256786bf5c82932ec23c3b74d9f05a6f95a8b5529352656664bac'.decode('hex')
 747     IDENTIFIER = 'fc70035c7a81bc6f'.decode('hex')
 748     PREFIX = '2472ef181efcd37b'.decode('hex')
 749     NAME = 'bitcoin'
 750     P2P_PORT = 9333
 751     MAX_TARGET = 2**256//2**32 - 1
 752     PERSIST = False
 753     WORKER_PORT = 9332
 754
 755 class BitcoinTestnet(bitcoin_data.Testnet):
 756     SHARE_PERIOD = 1 # seconds
 757     CHAIN_LENGTH = 24*60*60//5 # shares
 758     TARGET_LOOKBEHIND = 200 # shares
 759     SPREAD = 3 # blocks
 760     SCRIPT = '410403ad3dee8ab3d8a9ce5dd2abfbe7364ccd9413df1d279bf1a207849310465b0956e5904b1155ecd17574778f9949589ebfd4fb33ce837c241474a225cf08d85dac'.decode('hex')
 761     IDENTIFIER = '5fc2be2d4f0d6bfb'.decode('hex')
 762     PREFIX = '3f6057a15036f441'.decode('hex')
 763     NAME = 'bitcoin_testnet'
 764     P2P_PORT = 19333
 765     MAX_TARGET = 2**256//2**32 - 1
 766     PERSIST = False
 767     WORKER_PORT = 19332
 768
 769 class NamecoinMainnet(namecoin.Mainnet):
 770     SHARE_PERIOD = 10 # seconds
 771     CHAIN_LENGTH = 24*60*60//10 # shares
 772     TARGET_LOOKBEHIND = 3600//10 # shares
 773     SPREAD = 3 # blocks
 774     SCRIPT = '41043da5beb73f8f18cede1a41b0ed953123f1342b8e0216ab5bf71ed3e024201b4017f472bddb6041f17978d89ed8f8ed84f9e726b0bca80cacf96347c7153e8df0ac'.decode('hex')
 775     IDENTIFIER = 'd5b1192062c4c454'.decode('hex')
 776     PREFIX = 'b56f3d0fb24fc982'.decode('hex')
 777     NAME = 'namecoin'
 778     P2P_PORT = 9334
 779     MAX_TARGET = 2**256//2**32 - 1
 780     PERSIST = True
 781     WORKER_PORT = 9331
 782
 783 class NamecoinTestnet(namecoin.Testnet):
 784     SHARE_PERIOD = 1 # seconds
 785     CHAIN_LENGTH = 24*60*60//5 # shares
 786     TARGET_LOOKBEHIND = 200 # shares
 787     SPREAD = 3 # blocks
 788     SCRIPT = '410403ad3dee8ab3d8a9ce5dd2abfbe7364ccd9413df1d279bf1a207849310465b0956e5904b1155ecd17574778f9949589ebfd4fb33ce837c241474a225cf08d85dac'.decode('hex')
 789     IDENTIFIER = '8dd303d014a01a60'.decode('hex')
 790     PREFIX = '4d6581d24f51acbf'.decode('hex')
 791     NAME = 'namecoin_testnet'
 792     P2P_PORT = 19334
 793     MAX_TARGET = 2**256//2**20 - 1
 794     PERSIST = False
 795     WORKER_PORT = 19331
 796
 797 class IxcoinMainnet(ixcoin.Mainnet):
 798     SHARE_PERIOD = 10 # seconds
 799     CHAIN_LENGTH = 24*60*60//10 # shares
 800     TARGET_LOOKBEHIND = 3600//10 # shares
 801     SPREAD = 3 # blocks
 802     SCRIPT = '41043da5beb73f8f18cede1a41b0ed953123f1342b8e0216ab5bf71ed3e024201b4017f472bddb6041f17978d89ed8f8ed84f9e726b0bca80cacf96347c7153e8df0ac'.decode('hex')
 803     IDENTIFIER = '27b564116e2a2666'.decode('hex')
 804     PREFIX = '9dd6c4a619401f2f'.decode('hex')
 805     NAME = 'ixcoin'
 806     P2P_PORT = 9335
 807     MAX_TARGET = 2**256//2**32 - 1
 808     PERSIST = True
 809     WORKER_PORT = 9330
 810
 811 class IxcoinTestnet(ixcoin.Testnet):
 812     SHARE_PERIOD = 1 # seconds
 813     CHAIN_LENGTH = 24*60*60//5 # shares
 814     TARGET_LOOKBEHIND = 200 # shares
 815     SPREAD = 3 # blocks
 816     SCRIPT = '410403ad3dee8ab3d8a9ce5dd2abfbe7364ccd9413df1d279bf1a207849310465b0956e5904b1155ecd17574778f9949589ebfd4fb33ce837c241474a225cf08d85dac'.decode('hex')
 817     IDENTIFIER = '7430cbeb01249e44'.decode('hex')
 818     PREFIX = '7cfffda946709c1f'.decode('hex')
 819     NAME = 'ixcoin_testnet'
 820     P2P_PORT = 19335
 821     MAX_TARGET = 2**256//2**20 - 1
 822     PERSIST = False
 823     WORKER_PORT = 19330
 824
 825 class I0coinMainnet(i0coin.Mainnet):
 826     SHARE_PERIOD = 10 # seconds
 827     CHAIN_LENGTH = 24*60*60//10 # shares
 828     TARGET_LOOKBEHIND = 3600//10 # shares
 829     SPREAD = 3 # blocks
 830     SCRIPT = '410403ad3dee8ab3d8a9ce5dd2abfbe7364ccd9413df1d279bf1a207849310465b0956e5904b1155ecd17574778f9949589ebfd4fb33ce837c241474a225cf08d85dac'.decode('hex')
 831     IDENTIFIER = 'b32e3f10c2ff221b'.decode('hex')
 832     PREFIX = '6155537ed977a3b5'.decode('hex')
 833     NAME = 'i0coin'
 834     P2P_PORT = 9336
 835     MAX_TARGET = 2**256//2**32 - 1
 836     PERSIST = False
 837     WORKER_PORT = 9329
 838
 839 class I0coinTestnet(i0coin.Testnet):
 840     SHARE_PERIOD = 1 # seconds
 841     CHAIN_LENGTH = 24*60*60//5 # shares
 842     TARGET_LOOKBEHIND = 200 # shares
 843     SPREAD = 3 # blocks
 844     SCRIPT = '410403ad3dee8ab3d8a9ce5dd2abfbe7364ccd9413df1d279bf1a207849310465b0956e5904b1155ecd17574778f9949589ebfd4fb33ce837c241474a225cf08d85dac'.decode('hex')
 845     IDENTIFIER = '7712c1a8181b5f2e'.decode('hex')
 846     PREFIX = '792d2e7d770fbe68'.decode('hex')
 847     NAME = 'i0coin_testnet'
 848     P2P_PORT = 19336
 849     MAX_TARGET = 2**256//2**20 - 1
 850     PERSIST = False
 851     WORKER_PORT = 19329
 852
 853 class SolidcoinMainnet(solidcoin.Mainnet):
 854     SHARE_PERIOD = 10
 855     CHAIN_LENGTH = 24*60*60//10 # shares
 856     TARGET_LOOKBEHIND = 3600//10 # shares
 857     SPREAD = 3 # blocks
 858     SCRIPT = bitcoin_data.pubkey_hash_to_script2(bitcoin_data.address_to_pubkey_hash('sMKZ1yxHETxPYKh4Z2anWnwZDJZU7ztroy', solidcoin.Mainnet))
 859     IDENTIFIER = '9cc9c421cca258cd'.decode('hex')
 860     PREFIX = 'c059125b8070f00a'.decode('hex')
 861     NAME = 'solidcoin'
 862     P2P_PORT = 9337
 863     MAX_TARGET = 2**256//2**32 - 1
 864     PERSIST = True
 865     WORKER_PORT = 9328
 866
 867 class LitecoinMainnet(litecoin.Mainnet):
 868     SHARE_PERIOD = 10 # seconds
 869     CHAIN_LENGTH = 24*60*60//5 # shares
 870     TARGET_LOOKBEHIND = 200 # shares
 871     SPREAD = 12 # blocks
 872     SCRIPT = None # no fee
 873     IDENTIFIER = 'e037d5b8c6923410'.decode('hex')
 874     PREFIX = '7208c1a53ef629b0'.decode('hex')
 875     NAME = 'litecoin'
 876     P2P_PORT = 9338
 877     MAX_TARGET = 2**256//2**20 - 1
 878     PERSIST = True
 879     WORKER_PORT = 9327
 880
 881 class LitecoinTestnet(litecoin.Testnet):
 882     SHARE_PERIOD = 1 # seconds
 883     CHAIN_LENGTH = 24*60*60//5 # shares
 884     TARGET_LOOKBEHIND = 200 # shares
 885     SPREAD = 12 # blocks
 886     SCRIPT = None # no fee
 887     IDENTIFIER = 'cca5e24ec6408b1e'.decode('hex')
 888     PREFIX = 'ad9614f6466a39cf'.decode('hex')
 889     NAME = 'litecoin_testnet'
 890     P2P_PORT = 19338
 891     MAX_TARGET = 2**256//2**17 - 1
 892     PERSIST = False
 893     WORKER_PORT = 19327
 894
 895 nets = dict((net.NAME, net) for net in set([BitcoinMainnet, BitcoinTestnet, NamecoinMainnet, NamecoinTestnet, IxcoinMainnet, IxcoinTestnet, I0coinMainnet, I0coinTestnet, SolidcoinMainnet, LitecoinMainnet, LitecoinTestnet]))