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352 lines
13 KiB
352 lines
13 KiB
# 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 . import util |
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from . import bitcoin |
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from .bitcoin import * |
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MAX_TARGET = 0x00000000FFFF0000000000000000000000000000000000000000000000000000 |
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def serialize_header(res): |
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s = int_to_hex(res.get('version'), 4) \ |
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+ rev_hex(res.get('prev_block_hash')) \ |
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+ rev_hex(res.get('merkle_root')) \ |
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+ int_to_hex(int(res.get('timestamp')), 4) \ |
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+ int_to_hex(int(res.get('bits')), 4) \ |
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+ int_to_hex(int(res.get('nonce')), 4) |
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return s |
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def deserialize_header(s, height): |
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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): |
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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_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 = bitcoin.NetworkConstants.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 bitcoin.NetworkConstants.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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def verify_chunk(self, index, data): |
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num = len(data) // 80 |
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prev_hash = self.get_hash(index * 2016 - 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*80:(i+1) * 80] |
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header = deserialize_header(raw_header, index*2016 + 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 * 2016 - self.checkpoint) * 80 |
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if d < 0: |
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chunk = chunk[-d:] |
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d = 0 |
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self.write(chunk, d) |
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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)*80) |
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parent_data = f.read(parent_branch_size*80) |
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self.write(parent_data, 0) |
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parent.write(my_data, (checkpoint - parent.checkpoint)*80) |
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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): |
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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 offset != self._size*80: |
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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) == 80 |
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self.write(data, delta*80) |
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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 * 80) |
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h = f.read(80) |
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if h == bytes([0])*80: |
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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 bitcoin.NetworkConstants.GENESIS |
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elif height < len(self.checkpoints) * 2016: |
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assert (height+1) % 2016 == 0 |
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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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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 bitcoin.NetworkConstants.TESTNET: |
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return 0, 0 |
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if index == -1: |
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return 0x1d00ffff, 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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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) == bitcoin.NetworkConstants.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 // 2016 - 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 failed', 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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