1 from __future__ import division
7 from twisted.internet import defer
9 from . import base58, skiplists
10 from p2pool.util import bases, math, variable, expiring_dict, memoize, dicts
13 class EarlyEnd(Exception):
16 class LateEnd(Exception):
19 def read((data, pos), length):
20 data2 = data[pos:pos + length]
21 if len(data2) != length:
23 return data2, (data, pos + length)
25 def size((data, pos)):
26 return len(data) - pos
29 # the same data can have only one unpacked representation, but multiple packed binary representations
32 rval = getattr(self, '_hash', None)
35 rval = self._hash = hash((type(self), frozenset(self.__dict__.items())))
41 def __eq__(self, other):
42 return type(other) is type(self) and other.__dict__ == self.__dict__
44 def __ne__(self, other):
45 return not (self == other)
47 def _unpack(self, data):
48 obj, (data2, pos) = self.read((data, 0))
58 f = self.write(None, obj)
68 def unpack(self, data):
69 obj = self._unpack(data)
72 data2 = self._pack(obj)
74 if self._unpack(data2) != obj:
75 raise AssertionError()
80 data = self._pack(obj)
83 if self._unpack(data) != obj:
84 raise AssertionError((self._unpack(data), obj))
88 _backing = expiring_dict.ExpiringDict(100)
89 pack2 = memoize.memoize_with_backing(_backing, [unpack])(pack2)
90 unpack = memoize.memoize_with_backing(_backing)(unpack) # doesn't have an inverse
93 return self.pack2(dicts.immutify(obj))
96 def pack_base58(self, obj):
97 return base58.base58_encode(self.pack(obj))
99 def unpack_base58(self, base58_data):
100 return self.unpack(base58.base58_decode(base58_data))
103 def hash160(self, obj):
104 return ShortHashType().unpack(hashlib.new('ripemd160', hashlib.sha256(self.pack(obj)).digest()).digest())
106 def hash256(self, obj):
107 return HashType().unpack(hashlib.sha256(hashlib.sha256(self.pack(obj)).digest()).digest())
109 class VarIntType(Type):
110 # redundancy doesn't matter here because bitcoin and p2pool both reencode before hashing
111 def read(self, file):
112 data, file = read(file, 1)
117 desc, length = '<H', 2
119 desc, length = '<I', 4
121 desc, length = '<Q', 8
123 raise AssertionError()
124 data, file = read(file, length)
125 return struct.unpack(desc, data)[0], file
127 def write(self, file, item):
129 file = file, struct.pack('<B', item)
131 file = file, struct.pack('<BH', 0xfd, item)
132 elif item <= 0xffffffff:
133 file = file, struct.pack('<BI', 0xfe, item)
134 elif item <= 0xffffffffffffffff:
135 file = file, struct.pack('<BQ', 0xff, item)
137 raise ValueError('int too large for varint')
140 class VarStrType(Type):
141 _inner_size = VarIntType()
143 def read(self, file):
144 length, file = self._inner_size.read(file)
145 return read(file, length)
147 def write(self, file, item):
148 return self._inner_size.write(file, len(item)), item
150 class FixedStrType(Type):
151 def __init__(self, length):
154 def read(self, file):
155 return read(file, self.length)
157 def write(self, file, item):
158 if len(item) != self.length:
159 raise ValueError('incorrect length item!')
162 class EnumType(Type):
163 def __init__(self, inner, values):
165 self.values = dicts.frozendict(values)
168 for k, v in values.iteritems():
170 raise ValueError('duplicate value in values')
172 self.keys = dicts.frozendict(keys)
174 def read(self, file):
175 data, file = self.inner.read(file)
176 if data not in self.keys:
177 raise ValueError('enum data (%r) not in values (%r)' % (data, self.values))
178 return self.keys[data], file
180 def write(self, file, item):
181 if item not in self.values:
182 raise ValueError('enum item (%r) not in values (%r)' % (item, self.values))
183 return self.inner.write(file, self.values[item])
185 class HashType(Type):
186 def read(self, file):
187 data, file = read(file, 256//8)
188 return int(data[::-1].encode('hex'), 16), file
190 def write(self, file, item):
191 if not 0 <= item < 2**256:
192 raise ValueError('invalid hash value - %r' % (item,))
193 if item != 0 and item < 2**160:
194 print 'Very low hash value - maybe you meant to use ShortHashType? %x' % (item,)
195 return file, ('%064x' % (item,)).decode('hex')[::-1]
197 class ShortHashType(Type):
198 def read(self, file):
199 data, file = read(file, 160//8)
200 return int(data[::-1].encode('hex'), 16), file
202 def write(self, file, item):
203 if not 0 <= item < 2**160:
204 raise ValueError('invalid hash value - %r' % (item,))
205 return file, ('%040x' % (item,)).decode('hex')[::-1]
207 class ListType(Type):
208 _inner_size = VarIntType()
210 def __init__(self, type):
213 def read(self, file):
214 length, file = self._inner_size.read(file)
216 for i in xrange(length):
217 item, file = self.type.read(file)
221 def write(self, file, item):
222 file = self._inner_size.write(file, len(item))
224 file = self.type.write(file, subitem)
227 class StructType(Type):
228 def __init__(self, desc):
230 self.length = struct.calcsize(self.desc)
232 def read(self, file):
233 data, file = read(file, self.length)
234 res, = struct.unpack(self.desc, data)
237 def write(self, file, item):
238 data = struct.pack(self.desc, item)
239 if struct.unpack(self.desc, data)[0] != item:
240 # special test because struct doesn't error on some overflows
241 raise ValueError('''item didn't survive pack cycle (%r)''' % (item,))
244 class IPV6AddressType(Type):
245 def read(self, file):
246 data, file = read(file, 16)
247 if data[:12] != '00000000000000000000ffff'.decode('hex'):
248 raise ValueError('ipv6 addresses not supported yet')
249 return '.'.join(str(ord(x)) for x in data[12:]), file
251 def write(self, file, item):
252 bits = map(int, item.split('.'))
254 raise ValueError('invalid address: %r' % (bits,))
255 data = '00000000000000000000ffff'.decode('hex') + ''.join(chr(x) for x in bits)
256 assert len(data) == 16, len(data)
261 def get_record(fields):
262 fields = tuple(sorted(fields))
265 if fields not in _record_types:
266 class _Record(object):
269 return repr(dict(self))
270 def __getitem__(self, key):
271 return getattr(self, key)
272 def __setitem__(self, key, value):
273 setattr(self, key, value)
275 # for field in self.__slots__:
276 # yield field, getattr(self, field)
278 return self.__slots__
279 def __eq__(self, other):
280 if isinstance(other, dict):
281 return dict(self) == other
282 elif isinstance(other, _Record):
283 return all(self[k] == other[k] for k in self.keys())
285 def __ne__(self, other):
286 return not (self == other)
287 _record_types[fields] = _Record
288 return _record_types[fields]()
290 class ComposedType(Type):
291 def __init__(self, fields):
292 self.fields = tuple(fields)
294 def read(self, file):
295 item = get_record(k for k, v in self.fields)
296 for key, type_ in self.fields:
297 item[key], file = type_.read(file)
300 def write(self, file, item):
301 for key, type_ in self.fields:
302 file = type_.write(file, item[key])
305 class ChecksummedType(Type):
306 def __init__(self, inner):
309 def read(self, file):
310 obj, file = self.inner.read(file)
311 data = self.inner.pack(obj)
313 checksum, file = read(file, 4)
314 if checksum != hashlib.sha256(hashlib.sha256(data).digest()).digest()[:4]:
315 raise ValueError('invalid checksum')
319 def write(self, file, item):
320 data = self.inner.pack(item)
321 return (file, data), hashlib.sha256(hashlib.sha256(data).digest()).digest()[:4]
323 class FloatingInteger(object):
324 __slots__ = ['_bits']
327 def from_target_upper_bound(cls, target):
328 n = bases.natural_to_string(target)
329 if n and ord(n[0]) >= 128:
331 bits2 = (chr(len(n)) + (n + 3*chr(0))[:3])[::-1]
332 bits = struct.unpack('<I', bits2)[0]
335 def __init__(self, bits):
340 return math.shift_left(self._bits & 0x00ffffff, 8 * ((self._bits >> 24) - 3))
343 return hash(self._value)
345 def __cmp__(self, other):
346 if isinstance(other, FloatingInteger):
347 return cmp(self._value, other._value)
348 elif isinstance(other, (int, long)):
349 return cmp(self._value, other)
351 raise NotImplementedError()
357 return 'FloatingInteger(bits=%s (%x))' % (hex(self._bits), self)
359 def __add__(self, other):
360 if isinstance(other, (int, long)):
361 return self._value + other
362 raise NotImplementedError()
364 def __mul__(self, other):
365 if isinstance(other, (int, long)):
366 return self._value * other
367 raise NotImplementedError()
369 def __truediv__(self, other):
370 if isinstance(other, (int, long)):
371 return self._value / other
372 raise NotImplementedError()
373 def __floordiv__(self, other):
374 if isinstance(other, (int, long)):
375 return self._value // other
376 raise NotImplementedError()
377 __div__ = __truediv__
378 def __rtruediv__(self, other):
379 if isinstance(other, (int, long)):
380 return other / self._value
381 raise NotImplementedError()
382 def __rfloordiv__(self, other):
383 if isinstance(other, (int, long)):
384 return other // self._value
385 raise NotImplementedError()
386 __rdiv__ = __rtruediv__
388 class FloatingIntegerType(Type):
389 _inner = StructType('<I')
391 def read(self, file):
392 bits, file = self._inner.read(file)
393 return FloatingInteger(bits), file
395 def write(self, file, item):
396 return self._inner.write(file, item._bits)
398 class PossiblyNoneType(Type):
399 def __init__(self, none_value, inner):
400 self.none_value = none_value
403 def read(self, file):
404 value, file = self.inner.read(file)
405 return None if value == self.none_value else value, file
407 def write(self, file, item):
408 if item == self.none_value:
409 raise ValueError('none_value used')
410 return self.inner.write(file, self.none_value if item is None else item)
412 address_type = ComposedType([
413 ('services', StructType('<Q')),
414 ('address', IPV6AddressType()),
415 ('port', StructType('>H')),
418 tx_type = ComposedType([
419 ('version', StructType('<I')),
420 ('tx_ins', ListType(ComposedType([
421 ('previous_output', PossiblyNoneType(dicts.frozendict(hash=0, index=2**32 - 1), ComposedType([
422 ('hash', HashType()),
423 ('index', StructType('<I')),
425 ('script', VarStrType()),
426 ('sequence', PossiblyNoneType(2**32 - 1, StructType('<I'))),
428 ('tx_outs', ListType(ComposedType([
429 ('value', StructType('<Q')),
430 ('script', VarStrType()),
432 ('lock_time', StructType('<I')),
435 block_header_type = ComposedType([
436 ('version', StructType('<I')),
437 ('previous_block', PossiblyNoneType(0, HashType())),
438 ('merkle_root', HashType()),
439 ('timestamp', StructType('<I')),
440 ('target', FloatingIntegerType()),
441 ('nonce', StructType('<I')),
444 block_type = ComposedType([
445 ('header', block_header_type),
446 ('txs', ListType(tx_type)),
450 merkle_record_type = ComposedType([
451 ('left', HashType()),
452 ('right', HashType()),
455 def merkle_hash(tx_list):
458 hash_list = map(tx_type.hash256, tx_list)
459 while len(hash_list) > 1:
460 hash_list = [merkle_record_type.hash256(dict(left=left, right=left if right is None else right))
461 for left, right in zip(hash_list[::2], hash_list[1::2] + [None])]
464 def target_to_average_attempts(target):
465 return 2**256//(target + 1)
469 def tx_get_sigop_count(tx):
470 return sum(script.get_sigop_count(txin['script']) for txin in tx['tx_ins']) + sum(script.get_sigop_count(txout['script']) for txout in tx['tx_outs'])
474 human_address_type = ChecksummedType(ComposedType([
475 ('version', StructType('<B')),
476 ('pubkey_hash', ShortHashType()),
479 pubkey_type = FixedStrType(65)
481 def pubkey_hash_to_address(pubkey_hash, net):
482 return human_address_type.pack_base58(dict(version=net.BITCOIN_ADDRESS_VERSION, pubkey_hash=pubkey_hash))
484 def pubkey_to_address(pubkey, net):
485 return pubkey_hash_to_address(pubkey_type.hash160(pubkey), net)
487 def address_to_pubkey_hash(address, net):
488 x = human_address_type.unpack_base58(address)
489 if x['version'] != net.BITCOIN_ADDRESS_VERSION:
490 raise ValueError('address not for this net!')
491 return x['pubkey_hash']
495 def pubkey_to_script2(pubkey):
496 return ('\x41' + pubkey_type.pack(pubkey)) + '\xac'
498 def pubkey_hash_to_script2(pubkey_hash):
499 return '\x76\xa9' + ('\x14' + ShortHashType().pack(pubkey_hash)) + '\x88\xac'
501 def script2_to_human(script2, net):
503 pubkey = script2[1:-1]
504 script2_test = pubkey_to_script2(pubkey)
508 if script2_test == script2:
509 return 'Pubkey. Address: %s' % (pubkey_to_address(pubkey, net),)
512 pubkey_hash = ShortHashType().unpack(script2[3:-2])
513 script2_test2 = pubkey_hash_to_script2(pubkey_hash)
517 if script2_test2 == script2:
518 return 'Address. Address: %s' % (pubkey_hash_to_address(pubkey_hash, net),)
520 return 'Unknown. Script: %s' % (script2.encode('hex'),)
522 # linked list tracker
524 class Tracker(object):
526 self.shares = {} # hash -> share
527 #self.ids = {} # hash -> (id, height)
528 self.reverse_shares = {} # previous_hash -> set of share_hashes
530 self.heads = {} # head hash -> tail_hash
531 self.tails = {} # tail hash -> set of head hashes
533 self.heights = {} # share_hash -> height_to, ref, work_inc
534 self.reverse_heights = {} # ref -> set of share_hashes
536 self.ref_generator = itertools.count()
537 self.height_refs = {} # ref -> height, share_hash, work_inc
538 self.reverse_height_refs = {} # share_hash -> ref
540 self.get_nth_parent_hash = skiplists.DistanceSkipList(self)
542 self.added = variable.Event()
543 self.removed = variable.Event()
545 def add(self, share):
546 assert not isinstance(share, (int, long, type(None)))
547 if share.hash in self.shares:
548 raise ValueError('share already present')
550 if share.hash in self.tails:
551 heads = self.tails.pop(share.hash)
553 heads = set([share.hash])
555 if share.previous_hash in self.heads:
556 tail = self.heads.pop(share.previous_hash)
558 tail = self.get_last(share.previous_hash)
559 #tail2 = share.previous_hash
560 #while tail2 in self.shares:
561 # tail2 = self.shares[tail2].previous_hash
562 #assert tail == tail2
564 self.shares[share.hash] = share
565 self.reverse_shares.setdefault(share.previous_hash, set()).add(share.hash)
567 self.tails.setdefault(tail, set()).update(heads)
568 if share.previous_hash in self.tails[tail]:
569 self.tails[tail].remove(share.previous_hash)
572 self.heads[head] = tail
574 self.added.happened(share)
578 for s in self.shares.itervalues():
581 assert self.shares == t.shares, (self.shares, t.shares)
582 assert self.reverse_shares == t.reverse_shares, (self.reverse_shares, t.reverse_shares)
583 assert self.heads == t.heads, (self.heads, t.heads)
584 assert self.tails == t.tails, (self.tails, t.tails)
586 def remove(self, share_hash):
587 assert isinstance(share_hash, (int, long, type(None)))
588 if share_hash not in self.shares:
591 share = self.shares[share_hash]
594 children = self.reverse_shares.get(share.hash, set())
596 # move height refs referencing children down to this, so they can be moved up in one step
597 if share.previous_hash in self.reverse_height_refs:
598 for x in list(self.reverse_heights.get(self.reverse_height_refs.get(share.hash, object()), set())):
600 assert share.hash not in self.reverse_height_refs, list(self.reverse_heights.get(self.reverse_height_refs.get(share.hash, None), set()))
602 if share.hash in self.heads and share.previous_hash in self.tails:
603 tail = self.heads.pop(share.hash)
604 self.tails[tail].remove(share.hash)
605 if not self.tails[share.previous_hash]:
606 self.tails.pop(share.previous_hash)
607 elif share.hash in self.heads:
608 tail = self.heads.pop(share.hash)
609 self.tails[tail].remove(share.hash)
610 if self.reverse_shares[share.previous_hash] != set([share.hash]):
613 self.tails[tail].add(share.previous_hash)
614 self.heads[share.previous_hash] = tail
615 elif share.previous_hash in self.tails:
616 heads = self.tails[share.previous_hash]
617 if len(self.reverse_shares[share.previous_hash]) > 1:
618 raise NotImplementedError()
620 del self.tails[share.previous_hash]
622 self.heads[head] = share.hash
623 self.tails[share.hash] = set(heads)
625 raise NotImplementedError()
627 # move ref pointing to this up
628 if share.previous_hash in self.reverse_height_refs:
629 assert share.hash not in self.reverse_height_refs, list(self.reverse_heights.get(self.reverse_height_refs.get(share.hash, object()), set()))
631 ref = self.reverse_height_refs[share.previous_hash]
632 cur_height, cur_hash, cur_work = self.height_refs[ref]
633 assert cur_hash == share.previous_hash
634 self.height_refs[ref] = cur_height - 1, share.hash, cur_work - target_to_average_attempts(share.target)
635 del self.reverse_height_refs[share.previous_hash]
636 self.reverse_height_refs[share.hash] = ref
638 # delete height entry, and ref if it is empty
639 if share.hash in self.heights:
640 _, ref, _ = self.heights.pop(share.hash)
641 self.reverse_heights[ref].remove(share.hash)
642 if not self.reverse_heights[ref]:
643 del self.reverse_heights[ref]
644 _, ref_hash, _ = self.height_refs.pop(ref)
645 del self.reverse_height_refs[ref_hash]
647 self.shares.pop(share.hash)
648 self.reverse_shares[share.previous_hash].remove(share.hash)
649 if not self.reverse_shares[share.previous_hash]:
650 self.reverse_shares.pop(share.previous_hash)
652 #assert self.test() is None
653 self.removed.happened(share)
655 def get_height(self, share_hash):
656 height, work, last = self.get_height_work_and_last(share_hash)
659 def get_work(self, share_hash):
660 height, work, last = self.get_height_work_and_last(share_hash)
663 def get_last(self, share_hash):
664 height, work, last = self.get_height_work_and_last(share_hash)
667 def get_height_and_last(self, share_hash):
668 height, work, last = self.get_height_work_and_last(share_hash)
671 def _get_height_jump(self, share_hash):
672 if share_hash in self.heights:
673 height_to1, ref, work_inc1 = self.heights[share_hash]
674 height_to2, share_hash, work_inc2 = self.height_refs[ref]
675 height_inc = height_to1 + height_to2
676 work_inc = work_inc1 + work_inc2
678 height_inc, share_hash, work_inc = 1, self.shares[share_hash].previous_hash, target_to_average_attempts(self.shares[share_hash].target)
679 return height_inc, share_hash, work_inc
681 def _set_height_jump(self, share_hash, height_inc, other_share_hash, work_inc):
682 if other_share_hash not in self.reverse_height_refs:
683 ref = self.ref_generator.next()
684 assert ref not in self.height_refs
685 self.height_refs[ref] = 0, other_share_hash, 0
686 self.reverse_height_refs[other_share_hash] = ref
689 ref = self.reverse_height_refs[other_share_hash]
690 ref_height_to, ref_share_hash, ref_work_inc = self.height_refs[ref]
691 assert ref_share_hash == other_share_hash
693 if share_hash in self.heights:
694 prev_ref = self.heights[share_hash][1]
695 self.reverse_heights[prev_ref].remove(share_hash)
696 if not self.reverse_heights[prev_ref] and prev_ref != ref:
697 self.reverse_heights.pop(prev_ref)
698 _, x, _ = self.height_refs.pop(prev_ref)
699 self.reverse_height_refs.pop(x)
700 self.heights[share_hash] = height_inc - ref_height_to, ref, work_inc - ref_work_inc
701 self.reverse_heights.setdefault(ref, set()).add(share_hash)
703 def get_height_work_and_last(self, share_hash):
704 assert isinstance(share_hash, (int, long, type(None)))
709 while share_hash in self.shares:
710 updates.append((share_hash, height, work))
711 height_inc, share_hash, work_inc = self._get_height_jump(share_hash)
714 for update_hash, height_then, work_then in updates:
715 self._set_height_jump(update_hash, height - height_then, share_hash, work - work_then)
716 return height, work, share_hash
718 def get_chain_known(self, start_hash):
719 assert isinstance(start_hash, (int, long, type(None)))
721 Chain starting with item of hash I{start_hash} of items that this Tracker contains
723 item_hash_to_get = start_hash
725 if item_hash_to_get not in self.shares:
727 share = self.shares[item_hash_to_get]
728 assert not isinstance(share, long)
730 item_hash_to_get = share.previous_hash
732 def get_chain_to_root(self, start_hash, root=None):
733 assert isinstance(start_hash, (int, long, type(None)))
734 assert isinstance(root, (int, long, type(None)))
736 Chain of hashes starting with share_hash of shares to the root (doesn't include root)
737 Raises an error if one is missing
739 share_hash_to_get = start_hash
740 while share_hash_to_get != root:
741 share = self.shares[share_hash_to_get]
743 share_hash_to_get = share.previous_hash
745 def get_best_hash(self):
747 Returns hash of item with the most items in its chain
751 return max(self.heads, key=self.get_height_and_last)
753 def get_highest_height(self):
754 return max(self.get_height_and_last(head)[0] for head in self.heads) if self.heads else 0
756 def is_child_of(self, share_hash, possible_child_hash):
757 height, last = self.get_height_and_last(share_hash)
758 child_height, child_last = self.get_height_and_last(possible_child_hash)
759 if child_last != last:
760 return None # not connected, so can't be determined
761 height_up = child_height - height
762 return height_up >= 0 and self.get_nth_parent_hash(possible_child_hash, height_up) == share_hash
764 class FakeShare(object):
765 def __init__(self, **kwargs):
766 self.__dict__.update(kwargs)
768 if __name__ == '__main__':
772 for i in xrange(10000):
773 t.add(FakeShare(hash=i, previous_hash=i - 1 if i > 0 else None))
777 print 'HEADS', t.heads
778 print 'TAILS', t.tails
787 for i in xrange(random.randrange(100)):
788 x = random.choice(list(t.shares) + [None])
790 t.add(FakeShare(i, x))
792 x = random.choice(list(t.shares))
793 print 'DEL', x, t.__dict__
796 except NotImplementedError:
797 print 'aborted; not implemented'
800 print 'HEADS', t.heads
801 print 'TAILS', t.tails
803 #for share_hash, share in sorted(t.shares.iteritems()):
804 # print share_hash, share.previous_hash, t.heads.get(share_hash), t.tails.get(share_hash)
806 #import sys;sys.exit()
808 print t.get_nth_parent_hash(9000, 5000)
809 print t.get_nth_parent_hash(9001, 412)
810 #print t.get_nth_parent_hash(90, 51)
812 for share_hash in sorted(t.shares):
813 print str(share_hash).rjust(4),
814 x = t.skips.get(share_hash, None)
816 print str(x[0]).rjust(4),
818 print str(a).rjust(10),
821 # network definitions
823 class Mainnet(object):
824 BITCOIN_P2P_PREFIX = 'f9beb4d9'.decode('hex')
825 BITCOIN_P2P_PORT = 8333
826 BITCOIN_ADDRESS_VERSION = 0
827 BITCOIN_RPC_PORT = 8332
828 BITCOIN_RPC_CHECK = staticmethod(defer.inlineCallbacks(lambda bitcoind: defer.returnValue(
829 'name_firstupdate' not in (yield bitcoind.rpc_help()) and
830 'ixcoinaddress' not in (yield bitcoind.rpc_help()) and
831 not (yield bitcoind.rpc_getinfo())['testnet']
833 BITCOIN_SUBSIDY_FUNC = staticmethod(lambda height: 50*100000000 >> (height + 1)//210000)
834 BITCOIN_SYMBOL = 'BTC'
836 class Testnet(object):
837 BITCOIN_P2P_PREFIX = 'fabfb5da'.decode('hex')
838 BITCOIN_P2P_PORT = 18333
839 BITCOIN_ADDRESS_VERSION = 111
840 BITCOIN_RPC_PORT = 8332
841 BITCOIN_RPC_CHECK = staticmethod(defer.inlineCallbacks(lambda bitcoind: defer.returnValue(
842 'name_firstupdate' not in (yield bitcoind.rpc_help()) and
843 'ixcoinaddress' not in (yield bitcoind.rpc_help()) and
844 (yield bitcoind.rpc_getinfo())['testnet']
846 BITCOIN_SUBSIDY_FUNC = staticmethod(lambda height: 50*100000000 >> (height + 1)//210000)
847 BITCOIN_SYMBOL = 'tBTC'