mirror of
https://github.com/LBRYFoundation/LBRY-Vault.git
synced 2025-08-23 17:47:31 +00:00
453 lines
17 KiB
Python
453 lines
17 KiB
Python
# Electrum - lightweight Bitcoin client
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# Copyright (C) 2012 thomasv@ecdsa.org
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#
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# Permission is hereby granted, free of charge, to any person
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# obtaining a copy of this software and associated documentation files
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# (the "Software"), to deal in the Software without restriction,
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# including without limitation the rights to use, copy, modify, merge,
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# publish, distribute, sublicense, and/or sell copies of the Software,
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# and to permit persons to whom the Software is furnished to do so,
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# subject to the following conditions:
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#
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# The above copyright notice and this permission notice shall be
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# included in all copies or substantial portions of the Software.
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#
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# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
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# BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
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# ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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# CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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# SOFTWARE.
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import os
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import threading
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from typing import Optional, Dict
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from . import util
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from .bitcoin import hash_encode, int_to_hex, rev_hex
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from .crypto import sha256d
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from . import constants
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from .util import bfh, bh2u
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from .simple_config import SimpleConfig
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HEADER_SIZE = 80 # bytes
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MAX_TARGET = 0x00000000FFFF0000000000000000000000000000000000000000000000000000
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class MissingHeader(Exception):
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pass
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class InvalidHeader(Exception):
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pass
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def serialize_header(header_dict: dict) -> str:
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s = int_to_hex(header_dict['version'], 4) \
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+ rev_hex(header_dict['prev_block_hash']) \
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+ rev_hex(header_dict['merkle_root']) \
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+ int_to_hex(int(header_dict['timestamp']), 4) \
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+ int_to_hex(int(header_dict['bits']), 4) \
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+ int_to_hex(int(header_dict['nonce']), 4)
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return s
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def deserialize_header(s: bytes, height: int) -> dict:
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if not s:
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raise InvalidHeader('Invalid header: {}'.format(s))
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if len(s) != HEADER_SIZE:
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raise InvalidHeader('Invalid header length: {}'.format(len(s)))
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hex_to_int = lambda s: int('0x' + bh2u(s[::-1]), 16)
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h = {}
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h['version'] = hex_to_int(s[0:4])
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h['prev_block_hash'] = hash_encode(s[4:36])
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h['merkle_root'] = hash_encode(s[36:68])
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h['timestamp'] = hex_to_int(s[68:72])
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h['bits'] = hex_to_int(s[72:76])
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h['nonce'] = hex_to_int(s[76:80])
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h['block_height'] = height
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return h
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def hash_header(header: dict) -> str:
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if header is None:
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return '0' * 64
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if header.get('prev_block_hash') is None:
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header['prev_block_hash'] = '00'*32
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return hash_raw_header(serialize_header(header))
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def hash_raw_header(header: str) -> str:
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return hash_encode(sha256d(bfh(header)))
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blockchains = {} # type: Dict[int, Blockchain]
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blockchains_lock = threading.Lock()
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def read_blockchains(config: 'SimpleConfig') -> Dict[int, 'Blockchain']:
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blockchains[0] = Blockchain(config, 0, None)
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fdir = os.path.join(util.get_headers_dir(config), 'forks')
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util.make_dir(fdir)
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l = filter(lambda x: x.startswith('fork_'), os.listdir(fdir))
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l = sorted(l, key = lambda x: int(x.split('_')[1]))
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for filename in l:
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forkpoint = int(filename.split('_')[2])
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parent_id = int(filename.split('_')[1])
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b = Blockchain(config, forkpoint, parent_id)
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h = b.read_header(b.forkpoint)
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if b.parent().can_connect(h, check_height=False):
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blockchains[b.forkpoint] = b
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else:
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util.print_error("cannot connect", filename)
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return blockchains
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class Blockchain(util.PrintError):
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"""
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Manages blockchain headers and their verification
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"""
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def __init__(self, config: SimpleConfig, forkpoint: int, parent_id: Optional[int]):
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self.config = config
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self.forkpoint = forkpoint
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self.checkpoints = constants.net.CHECKPOINTS
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self.parent_id = parent_id
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assert parent_id != forkpoint
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self.lock = threading.RLock()
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with self.lock:
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self.update_size()
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def with_lock(func):
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def func_wrapper(self, *args, **kwargs):
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with self.lock:
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return func(self, *args, **kwargs)
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return func_wrapper
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def parent(self) -> 'Blockchain':
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return blockchains[self.parent_id]
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def get_max_child(self) -> Optional[int]:
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with blockchains_lock: chains = list(blockchains.values())
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children = list(filter(lambda y: y.parent_id==self.forkpoint, chains))
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return max([x.forkpoint for x in children]) if children else None
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def get_max_forkpoint(self) -> int:
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"""Returns the max height where there is a fork
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related to this chain.
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"""
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mc = self.get_max_child()
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return mc if mc is not None else self.forkpoint
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def get_branch_size(self) -> int:
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return self.height() - self.get_max_forkpoint() + 1
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def get_name(self) -> str:
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return self.get_hash(self.get_max_forkpoint()).lstrip('00')[0:10]
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def check_header(self, header: dict) -> bool:
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header_hash = hash_header(header)
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height = header.get('block_height')
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return self.check_hash(height, header_hash)
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def check_hash(self, height: int, header_hash: str) -> bool:
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"""Returns whether the hash of the block at given height
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is the given hash.
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"""
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assert isinstance(header_hash, str) and len(header_hash) == 64, header_hash # hex
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try:
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return header_hash == self.get_hash(height)
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except Exception:
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return False
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def fork(parent, header: dict) -> 'Blockchain':
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forkpoint = header.get('block_height')
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self = Blockchain(parent.config, forkpoint, parent.forkpoint)
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open(self.path(), 'w+').close()
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self.save_header(header)
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return self
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def height(self) -> int:
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return self.forkpoint + self.size() - 1
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def size(self) -> int:
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with self.lock:
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return self._size
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def update_size(self) -> None:
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p = self.path()
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self._size = os.path.getsize(p)//HEADER_SIZE if os.path.exists(p) else 0
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def verify_header(self, header: dict, prev_hash: str, target: int, expected_header_hash: str=None) -> None:
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_hash = hash_header(header)
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if expected_header_hash and expected_header_hash != _hash:
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raise Exception("hash mismatches with expected: {} vs {}".format(expected_header_hash, _hash))
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if prev_hash != header.get('prev_block_hash'):
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raise Exception("prev hash mismatch: %s vs %s" % (prev_hash, header.get('prev_block_hash')))
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if constants.net.TESTNET:
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return
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bits = self.target_to_bits(target)
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if bits != header.get('bits'):
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raise Exception("bits mismatch: %s vs %s" % (bits, header.get('bits')))
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if int('0x' + _hash, 16) > target:
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raise Exception("insufficient proof of work: %s vs target %s" % (int('0x' + _hash, 16), target))
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def verify_chunk(self, index: int, data: bytes) -> None:
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num = len(data) // HEADER_SIZE
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start_height = index * 2016
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prev_hash = self.get_hash(start_height - 1)
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target = self.get_target(index-1)
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for i in range(num):
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height = start_height + i
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try:
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expected_header_hash = self.get_hash(height)
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except MissingHeader:
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expected_header_hash = None
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raw_header = data[i*HEADER_SIZE : (i+1)*HEADER_SIZE]
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header = deserialize_header(raw_header, index*2016 + i)
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self.verify_header(header, prev_hash, target, expected_header_hash)
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prev_hash = hash_header(header)
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def path(self):
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d = util.get_headers_dir(self.config)
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if self.parent_id is None:
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filename = 'blockchain_headers'
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else:
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basename = 'fork_%d_%d' % (self.parent_id, self.forkpoint)
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filename = os.path.join('forks', basename)
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return os.path.join(d, filename)
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@with_lock
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def save_chunk(self, index: int, chunk: bytes):
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chunk_within_checkpoint_region = index < len(self.checkpoints)
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# chunks in checkpoint region are the responsibility of the 'main chain'
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if chunk_within_checkpoint_region and self.parent_id is not None:
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main_chain = blockchains[0]
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main_chain.save_chunk(index, chunk)
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return
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delta_height = (index * 2016 - self.forkpoint)
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delta_bytes = delta_height * HEADER_SIZE
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# if this chunk contains our forkpoint, only save the part after forkpoint
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# (the part before is the responsibility of the parent)
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if delta_bytes < 0:
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chunk = chunk[-delta_bytes:]
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delta_bytes = 0
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truncate = not chunk_within_checkpoint_region
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self.write(chunk, delta_bytes, truncate)
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self.swap_with_parent()
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@with_lock
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def swap_with_parent(self) -> None:
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if self.parent_id is None:
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return
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parent_branch_size = self.parent().height() - self.forkpoint + 1
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if parent_branch_size >= self.size():
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return
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self.print_error("swap", self.forkpoint, self.parent_id)
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parent_id = self.parent_id
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forkpoint = self.forkpoint
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parent = self.parent()
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self.assert_headers_file_available(self.path())
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with open(self.path(), 'rb') as f:
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my_data = f.read()
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self.assert_headers_file_available(parent.path())
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with open(parent.path(), 'rb') as f:
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f.seek((forkpoint - parent.forkpoint)*HEADER_SIZE)
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parent_data = f.read(parent_branch_size*HEADER_SIZE)
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self.write(parent_data, 0)
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parent.write(my_data, (forkpoint - parent.forkpoint)*HEADER_SIZE)
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# store file path
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with blockchains_lock: chains = list(blockchains.values())
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for b in chains:
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b.old_path = b.path()
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# swap parameters
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self.parent_id = parent.parent_id; parent.parent_id = parent_id
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self.forkpoint = parent.forkpoint; parent.forkpoint = forkpoint
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self._size = parent._size; parent._size = parent_branch_size
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# move files
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for b in chains:
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if b in [self, parent]: continue
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if b.old_path != b.path():
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self.print_error("renaming", b.old_path, b.path())
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os.rename(b.old_path, b.path())
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# update pointers
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with blockchains_lock:
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blockchains[self.forkpoint] = self
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blockchains[parent.forkpoint] = parent
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def assert_headers_file_available(self, path):
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if os.path.exists(path):
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return
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elif not os.path.exists(util.get_headers_dir(self.config)):
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raise FileNotFoundError('Electrum headers_dir does not exist. Was it deleted while running?')
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else:
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raise FileNotFoundError('Cannot find headers file but headers_dir is there. Should be at {}'.format(path))
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def write(self, data: bytes, offset: int, truncate: bool=True) -> None:
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filename = self.path()
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with self.lock:
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self.assert_headers_file_available(filename)
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with open(filename, 'rb+') as f:
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if truncate and offset != self._size * HEADER_SIZE:
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f.seek(offset)
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f.truncate()
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f.seek(offset)
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f.write(data)
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f.flush()
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os.fsync(f.fileno())
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self.update_size()
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@with_lock
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def save_header(self, header: dict) -> None:
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delta = header.get('block_height') - self.forkpoint
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data = bfh(serialize_header(header))
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# headers are only _appended_ to the end:
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assert delta == self.size()
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assert len(data) == HEADER_SIZE
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self.write(data, delta*HEADER_SIZE)
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self.swap_with_parent()
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def read_header(self, height: int) -> Optional[dict]:
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assert self.parent_id != self.forkpoint
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if height < 0:
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return
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if height < self.forkpoint:
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return self.parent().read_header(height)
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if height > self.height():
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return
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delta = height - self.forkpoint
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name = self.path()
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self.assert_headers_file_available(name)
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with open(name, 'rb') as f:
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f.seek(delta * HEADER_SIZE)
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h = f.read(HEADER_SIZE)
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if len(h) < HEADER_SIZE:
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raise Exception('Expected to read a full header. This was only {} bytes'.format(len(h)))
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if h == bytes([0])*HEADER_SIZE:
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return None
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return deserialize_header(h, height)
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def get_hash(self, height: int) -> str:
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def is_height_checkpoint():
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within_cp_range = height <= constants.net.max_checkpoint()
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at_chunk_boundary = (height+1) % 2016 == 0
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return within_cp_range and at_chunk_boundary
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if height == -1:
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return '0000000000000000000000000000000000000000000000000000000000000000'
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elif height == 0:
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return constants.net.GENESIS
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elif is_height_checkpoint():
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index = height // 2016
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h, t = self.checkpoints[index]
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return h
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else:
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header = self.read_header(height)
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if header is None:
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raise MissingHeader(height)
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return hash_header(header)
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def get_target(self, index: int) -> int:
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# compute target from chunk x, used in chunk x+1
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if constants.net.TESTNET:
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return 0
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if index == -1:
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return MAX_TARGET
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if index < len(self.checkpoints):
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h, t = self.checkpoints[index]
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return t
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# new target
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first = self.read_header(index * 2016)
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last = self.read_header(index * 2016 + 2015)
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if not first or not last:
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raise MissingHeader()
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bits = last.get('bits')
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target = self.bits_to_target(bits)
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nActualTimespan = last.get('timestamp') - first.get('timestamp')
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nTargetTimespan = 14 * 24 * 60 * 60
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nActualTimespan = max(nActualTimespan, nTargetTimespan // 4)
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nActualTimespan = min(nActualTimespan, nTargetTimespan * 4)
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new_target = min(MAX_TARGET, (target * nActualTimespan) // nTargetTimespan)
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return new_target
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def bits_to_target(self, bits: int) -> int:
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bitsN = (bits >> 24) & 0xff
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if not (bitsN >= 0x03 and bitsN <= 0x1d):
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raise Exception("First part of bits should be in [0x03, 0x1d]")
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bitsBase = bits & 0xffffff
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if not (bitsBase >= 0x8000 and bitsBase <= 0x7fffff):
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raise Exception("Second part of bits should be in [0x8000, 0x7fffff]")
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return bitsBase << (8 * (bitsN-3))
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def target_to_bits(self, target: int) -> int:
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c = ("%064x" % target)[2:]
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while c[:2] == '00' and len(c) > 6:
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c = c[2:]
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bitsN, bitsBase = len(c) // 2, int('0x' + c[:6], 16)
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if bitsBase >= 0x800000:
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bitsN += 1
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bitsBase >>= 8
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return bitsN << 24 | bitsBase
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def can_connect(self, header: dict, check_height: bool=True) -> bool:
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if header is None:
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return False
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height = header['block_height']
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if check_height and self.height() != height - 1:
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#self.print_error("cannot connect at height", height)
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return False
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if height == 0:
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return hash_header(header) == constants.net.GENESIS
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try:
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prev_hash = self.get_hash(height - 1)
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except:
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return False
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if prev_hash != header.get('prev_block_hash'):
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return False
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try:
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target = self.get_target(height // 2016 - 1)
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except MissingHeader:
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return False
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try:
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self.verify_header(header, prev_hash, target)
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except BaseException as e:
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return False
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return True
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def connect_chunk(self, idx: int, hexdata: str) -> bool:
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try:
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data = bfh(hexdata)
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self.verify_chunk(idx, data)
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#self.print_error("validated chunk %d" % idx)
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self.save_chunk(idx, data)
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return True
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except BaseException as e:
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self.print_error('verify_chunk %d failed'%idx, str(e))
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return False
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def get_checkpoints(self):
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# for each chunk, store the hash of the last block and the target after the chunk
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cp = []
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n = self.height() // 2016
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for index in range(n):
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h = self.get_hash((index+1) * 2016 -1)
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target = self.get_target(index)
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cp.append((h, target))
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return cp
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def check_header(header: dict) -> Optional[Blockchain]:
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if type(header) is not dict:
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return None
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with blockchains_lock: chains = list(blockchains.values())
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for b in chains:
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if b.check_header(header):
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return b
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return None
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def can_connect(header: dict) -> Optional[Blockchain]:
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with blockchains_lock: chains = list(blockchains.values())
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for b in chains:
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if b.can_connect(header):
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return b
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return None
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