394 lines
14 KiB
Python
394 lines
14 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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import struct
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from io import BytesIO
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from . import util
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from . import bitcoin
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from . import constants
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from .bitcoin import *
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import base64
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from .equihash import is_gbp_valid
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import logging
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logging.basicConfig(level=logging.INFO)
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# https://en.bitcoin.it/wiki/Target
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MAX_TARGET = 0x0007FFFFFFFF0000000000000000000000000000000000000000000000000000
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def serialize_header(res):
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r = b''
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r += struct.pack("<i", res.get('version'))
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r += str_to_hash(res.get('prev_block_hash'))
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r += str_to_hash(res.get('merkle_root'))
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r += str_to_hash(res.get('hash_reserved'))
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r += struct.pack("<I", res.get('timestamp'))
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r += struct.pack("<I", res.get('bits'))
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r += str_to_hash(res.get('nonce'))
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r += ser_char_vector(base64.b64decode(res.get('n_solution').encode('utf8')))
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return r
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def deserialize_header(f, height):
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f = BytesIO(f)
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h = {}
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h['version'] = struct.unpack("<I", f.read(4))[0]
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h['prev_block_hash'] = hash_to_str(f.read(32))
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h['merkle_root'] = hash_to_str(f.read(32))
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h['hash_reserved'] = hash_to_str(f.read(32))
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h['timestamp'] = struct.unpack("<I", f.read(4))[0]
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h['bits'] = struct.unpack("<I", f.read(4))[0]
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h['nonce'] = hash_to_str(f.read(32))
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h['n_solution'] = base64.b64encode(bytes(deser_char_vector(f))).decode('utf8')
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h['block_height'] = height
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return h
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# def deserialize_header(f, height):
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# h = {}
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# h['version'] = struct.unpack("<I", f.read(4))[0]
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# h['prev_block_hash'] = hash_to_str(f.read(32))
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# h['merkle_root'] = hash_to_str(f.read(32))
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# h['hash_reserved'] = hash_to_str(f.read(32))
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# h['timestamp'] = struct.unpack("<I", f.read(4))[0]
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# h['bits'] = struct.unpack("<I", f.read(4))[0]
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# h['nonce'] = hash_to_str(f.read(32))
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# h['n_solution'] = base64.b64encode(bytes(deser_char_vector(f))).decode('utf8')
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# h['block_height'] = height
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# return h
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def sha256_header(header):
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return uint256_from_bytes(Hash(serialize_header(header)))
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def hash_header(header):
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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'*64
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'''
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TODO 32?
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'''
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return hash_encode(Hash(bfh(serialize_header(header))))
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blockchains = {}
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def read_blockchains(config):
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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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if not os.path.exists(fdir):
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os.mkdir(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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checkpoint = int(filename.split('_')[2])
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parent_id = int(filename.split('_')[1])
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b = Blockchain(config, checkpoint, parent_id)
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h = b.read_header(b.checkpoint)
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if b.parent().can_connect(h, check_height=False):
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blockchains[b.checkpoint] = 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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def check_header(header):
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if type(header) is not dict:
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return False
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for b in blockchains.values():
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if b.check_header(header):
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return b
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return False
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def can_connect(header):
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for b in blockchains.values():
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if b.can_connect(header):
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return b
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return False
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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, checkpoint, parent_id):
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self.config = config
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self.catch_up = None # interface catching up
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self.checkpoint = checkpoint
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self.checkpoints = constants.net.CHECKPOINTS
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self.parent_id = parent_id
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self.lock = threading.Lock()
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with self.lock:
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self.update_size()
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def parent(self):
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return blockchains[self.parent_id]
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def get_max_child(self):
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children = list(filter(lambda y: y.parent_id==self.checkpoint, blockchains.values()))
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return max([x.checkpoint for x in children]) if children else None
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def get_checkpoint(self):
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mc = self.get_max_child()
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return mc if mc is not None else self.checkpoint
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def get_branch_size(self):
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return self.height() - self.get_checkpoint() + 1
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def get_name(self):
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return self.get_hash(self.get_checkpoint()).lstrip('00')[0:10]
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def check_header(self, header):
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header_hash = hash_header(header)
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height = header.get('block_height')
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return header_hash == self.get_hash(height)
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def fork(parent, header):
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checkpoint = header.get('block_height')
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self = Blockchain(parent.config, checkpoint, parent.checkpoint)
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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):
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return self.checkpoint + self.size() - 1
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def size(self):
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with self.lock:
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return self._size
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def update_size(self):
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p = self.path()
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self._size = os.path.getsize(p)//80 if os.path.exists(p) else 0
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def verify_header(self, header, prev_hash, target):
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_hash = hash_header(header)
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if prev_hash != header.get('prev_block_hash'):
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raise BaseException("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 BaseException("bits mismatch: %s vs %s" % (bits, header.get('bits')))
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if int('0x' + _hash, 16) > target:
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raise BaseException("insufficient proof of work: %s vs target %s" % (int('0x' + _hash, 16), target))
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nonce = uint256_from_bytes(str_to_hash(header.get('nonce')))
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n_solution = vector_from_bytes(base64.b64decode(header.get('n_solution').encode('utf8')))
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if not is_gbp_valid(serialize_header(header), nonce, n_solution,
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constants.net.EQUIHASH_N, constants.net.EQUIHASH_K):
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raise BaseException("Equihash invalid")
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def verify_chunk(self, index, data):
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num = len(data) // bitcoin.HEADER_SIZE
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prev_hash = self.get_hash(index * constants.net.CHUNK_SIZE - 1)
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target = self.get_target(index-1)
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for i in range(num):
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raw_header = data[i*bitcoin.HEADER_SIZE:(i+1) * bitcoin.HEADER_SIZE]
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header = deserialize_header(raw_header, index*constants.net.CHUNK_SIZE + i)
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self.verify_header(header, prev_hash, target)
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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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filename = 'blockchain_headers' if self.parent_id is None else os.path.join('forks', 'fork_%d_%d'%(self.parent_id, self.checkpoint))
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return os.path.join(d, filename)
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def save_chunk(self, index, chunk):
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filename = self.path()
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d = (index * constants.net.CHUNK_SIZE - self.checkpoint) * bitcoin.HEADER_SIZE
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if d < 0:
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chunk = chunk[-d:]
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d = 0
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truncate = index >= len(self.checkpoints)
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self.write(chunk, d, truncate)
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self.swap_with_parent()
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def swap_with_parent(self):
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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.checkpoint + 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.checkpoint, self.parent_id)
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parent_id = self.parent_id
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checkpoint = self.checkpoint
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parent = self.parent()
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with open(self.path(), 'rb') as f:
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my_data = f.read()
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with open(parent.path(), 'rb') as f:
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f.seek((checkpoint - parent.checkpoint)*bitcoin.HEADER_SIZE)
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parent_data = f.read(parent_branch_size*bitcoin.HEADER_SIZE)
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self.write(parent_data, 0)
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parent.write(my_data, (checkpoint - parent.checkpoint)*bitcoin.HEADER_SIZE)
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# store file path
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for b in blockchains.values():
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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.checkpoint = parent.checkpoint; parent.checkpoint = checkpoint
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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 blockchains.values():
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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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blockchains[self.checkpoint] = self
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blockchains[parent.checkpoint] = parent
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def write(self, data, offset, truncate=True):
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filename = self.path()
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with self.lock:
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with open(filename, 'rb+') as f:
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if truncate and offset != self._size*bitcoin.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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def save_header(self, header):
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delta = header.get('block_height') - self.checkpoint
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data = bfh(serialize_header(header))
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assert delta == self.size()
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assert len(data) == bitcoin.HEADER_SIZE
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self.write(data, delta*bitcoin.HEADER_SIZE)
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self.swap_with_parent()
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def read_header(self, height):
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assert self.parent_id != self.checkpoint
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if height < 0:
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return
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if height < self.checkpoint:
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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.checkpoint
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name = self.path()
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if os.path.exists(name):
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with open(name, 'rb') as f:
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f.seek(delta * bitcoin.HEADER_SIZE)
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h = f.read(bitcoin.HEADER_SIZE)
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if h == bytes([0])*bitcoin.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):
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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 height < len(self.checkpoints) * constants.net.CHUNK_SIZE:
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assert (height+1) % constants.net.CHUNK_SIZE == 0, height
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index = height // constants.net.CHUNK_SIZE
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h, t = self.checkpoints[index]
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return h
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else:
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return hash_header(self.read_header(height))
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def get_target(self, index):
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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 * constants.net.CHUNK_SIZE)
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last = self.read_header(index * constants.net.CHUNK_SIZE + (constants.net.CHUNK_SIZE - 1))
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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):
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bitsN = (bits >> 24) & 0xff
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if not (bitsN >= 0x03 and bitsN <= 0x1d):
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raise BaseException("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 BaseException("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):
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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, check_height=True):
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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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target = self.get_target(height // constants.net.CHUNK_SIZE - 1)
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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, hexdata):
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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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