#!/usr/bin/env python # # Electrum - lightweight Bitcoin client # Copyright (C) 2012 thomasv@ecdsa.org # # Permission is hereby granted, free of charge, to any person # obtaining a copy of this software and associated documentation files # (the "Software"), to deal in the Software without restriction, # including without limitation the rights to use, copy, modify, merge, # publish, distribute, sublicense, and/or sell copies of the Software, # and to permit persons to whom the Software is furnished to do so, # subject to the following conditions: # # The above copyright notice and this permission notice shall be # included in all copies or substantial portions of the Software. # # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, # EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF # MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND # NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS # BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN # ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN # CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE # SOFTWARE. import os import util import bitcoin from bitcoin import * MAX_TARGET = 0x00000000FFFF0000000000000000000000000000000000000000000000000000 def serialize_header(res): s = int_to_hex(res.get('version'), 4) \ + rev_hex(res.get('prev_block_hash')) \ + rev_hex(res.get('merkle_root')) \ + int_to_hex(int(res.get('timestamp')), 4) \ + int_to_hex(int(res.get('bits')), 4) \ + int_to_hex(int(res.get('nonce')), 4) return s def deserialize_header(s, height): hex_to_int = lambda s: int('0x' + s[::-1].encode('hex'), 16) h = {} h['version'] = hex_to_int(s[0:4]) h['prev_block_hash'] = hash_encode(s[4:36]) h['merkle_root'] = hash_encode(s[36:68]) h['timestamp'] = hex_to_int(s[68:72]) h['bits'] = hex_to_int(s[72:76]) h['nonce'] = hex_to_int(s[76:80]) h['block_height'] = height return h def hash_header(header): if header is None: return '0' * 64 if header.get('prev_block_hash') is None: header['prev_block_hash'] = '00'*32 return hash_encode(Hash(serialize_header(header).decode('hex'))) blockchains = {} def read_blockchains(config): blockchains[0] = Blockchain(config, 'blockchain_headers') l = filter(lambda x: x.startswith('fork_'), os.listdir(config.path)) l = sorted(l, key = lambda x: int(x.split('_')[1])) for x in l: b = Blockchain(config, x) blockchains[b.checkpoint] = b return blockchains def check_header(header): if type(header) is not dict: return False for b in blockchains.values(): if b.check_header(header): return b return False def can_connect(header): for b in blockchains.values(): if b.can_connect(header): return b return False class Blockchain(util.PrintError): '''Manages blockchain headers and their verification''' def __init__(self, config, filename): self.config = config self.filename = filename self.catch_up = None # interface catching up self.is_saved = True self.headers = [] if filename == 'blockchain_headers': self.parent = None self.checkpoint = 0 elif filename.startswith('fork_'): self.parent = blockchains[int(filename.split('_')[1])] self.checkpoint = int(filename.split('_')[2]) else: raise BaseException('') def get_max_child(self): children = filter(lambda y: y.parent==self, blockchains.values()) return max([x.checkpoint for x in children]) if children else None def get_branch_size(self): mc = self.get_max_child() checkpoint = mc if mc is not None else self.checkpoint return self.height() - checkpoint def check_header(self, header): header_hash = hash_header(header) height = header.get('block_height') return header_hash == self.get_hash(height) def fork(parent, checkpoint): filename = 'fork_%d_%d'%(parent.checkpoint, checkpoint) self = Blockchain(parent.config, filename) self.is_saved = False return self def height(self): return self.checkpoint + self.size() - 1 def size(self): if self.is_saved: p = self.path() return os.path.getsize(p)/80 if os.path.exists(p) else 0 else: return len(self.headers) def verify_header(self, header, prev_header, bits, target): prev_hash = hash_header(prev_header) _hash = hash_header(header) if prev_hash != header.get('prev_block_hash'): raise BaseException("prev hash mismatch: %s vs %s" % (prev_hash, header.get('prev_block_hash'))) if bitcoin.TESTNET: return if bits != header.get('bits'): raise BaseException("bits mismatch: %s vs %s" % (bits, header.get('bits'))) if int('0x' + _hash, 16) > target: raise BaseException("insufficient proof of work: %s vs target %s" % (int('0x' + _hash, 16), target)) def verify_chain(self, chain): first_header = chain[0] prev_header = self.read_header(first_header.get('block_height') - 1) for header in chain: height = header.get('block_height') bits, target = self.get_target(height / 2016, chain) self.verify_header(header, prev_header, bits, target) prev_header = header def verify_chunk(self, index, data): num = len(data) / 80 prev_header = None if index != 0: prev_header = self.read_header(index*2016 - 1) bits, target = self.get_target(index) for i in range(num): raw_header = data[i*80:(i+1) * 80] header = deserialize_header(raw_header, index*2016 + i) self.verify_header(header, prev_header, bits, target) prev_header = header def path(self): d = util.get_headers_dir(self.config) return os.path.join(d, self.filename) def save_chunk(self, index, chunk): if not self.is_saved: self.save() filename = self.path() d = (index * 2016 - self.checkpoint) * 80 if d < 0: chunk = chunk[-d:] d = 0 with open(filename, 'rb+') as f: f.seek(d) f.write(chunk) def save(self): # recursively save parents if they have not been saved if self.parent and not self.parent.is_saved: self.parent.save() open(self.path(), 'w+').close() for h in self.headers: self.write_header(h) self.headers = [] self.is_saved = True self.print_error("saved", self.filename) def swap_with_parent(self): self.print_error("swap") parent = self.parent checkpoint = self.checkpoint # copy headers parent.headers = [parent.read_header(h) for h in range(checkpoint, checkpoint + parent.get_branch_size())] # truncate parent file with open(parent.path(), 'rb+') as f: f.seek(checkpoint*80) f.truncate() parent.is_saved = False # swap chains fn = self.filename; self.filename = parent.filename; parent.filename = fn self.parent = parent.parent; parent.parent = parent self.checkpoint = parent.checkpoint; parent.checkpoint = checkpoint # write my headers for h in self.headers: self.write_header(h) self.headers = [] self.is_saved = True def save_header(self, header): N = 10 height = header.get('block_height') if not self.is_saved: assert height == self.checkpoint + len(self.headers) self.headers.append(header) if len(self.headers) > N: if self.parent.get_branch_size() <= N: self.swap_with_parent() else: self.save() return self.write_header(header) def write_header(self, header): filename = self.path() delta = header.get('block_height') - self.checkpoint data = serialize_header(header).decode('hex') assert delta * 80 == os.path.getsize(filename) assert len(data) == 80 with open(filename, 'rb+') as f: f.seek(delta * 80) f.write(data) def read_header(self, height): if height < self.checkpoint: return self.parent.read_header(height) delta = height - self.checkpoint if not self.is_saved: if delta >= len(self.headers): return None header = self.headers[delta] assert header.get('block_height') == height return header name = self.path() if os.path.exists(name): f = open(name, 'rb') f.seek(delta * 80) h = f.read(80) f.close() if len(h) == 80: h = deserialize_header(h, height) return h def get_hash(self, height): return bitcoin.GENESIS if height == 0 else hash_header(self.read_header(height)) def BIP9(self, height, flag): v = self.read_header(height)['version'] return ((v & 0xE0000000) == 0x20000000) and ((v & flag) == flag) def segwit_support(self, N=144): h = self.local_height return sum([self.BIP9(h-i, 2) for i in range(N)])*10000/N/100. def truncate_headers(self, height): self.print_error('Truncating headers file at height %d'%height) name = self.path() f = open(name, 'rb+') f.seek(height * 80) f.truncate() f.close() def get_target(self, index, chain=None): if bitcoin.TESTNET: return 0, 0 if index == 0: return 0x1d00ffff, MAX_TARGET first = self.read_header((index-1) * 2016) last = self.read_header(index*2016 - 1) if last is None: for h in chain: if h.get('block_height') == index*2016 - 1: last = h assert last is not None # bits to target bits = last.get('bits') bitsN = (bits >> 24) & 0xff if not (bitsN >= 0x03 and bitsN <= 0x1d): raise BaseException("First part of bits should be in [0x03, 0x1d]") bitsBase = bits & 0xffffff if not (bitsBase >= 0x8000 and bitsBase <= 0x7fffff): raise BaseException("Second part of bits should be in [0x8000, 0x7fffff]") target = bitsBase << (8 * (bitsN-3)) # new target nActualTimespan = last.get('timestamp') - first.get('timestamp') nTargetTimespan = 14 * 24 * 60 * 60 nActualTimespan = max(nActualTimespan, nTargetTimespan / 4) nActualTimespan = min(nActualTimespan, nTargetTimespan * 4) new_target = min(MAX_TARGET, (target*nActualTimespan) / nTargetTimespan) # convert new target to bits c = ("%064x" % new_target)[2:] while c[:2] == '00' and len(c) > 6: c = c[2:] bitsN, bitsBase = len(c) / 2, int('0x' + c[:6], 16) if bitsBase >= 0x800000: bitsN += 1 bitsBase >>= 8 new_bits = bitsN << 24 | bitsBase return new_bits, bitsBase << (8 * (bitsN-3)) def can_connect(self, header): previous_height = header['block_height'] - 1 previous_header = self.read_header(previous_height) if not previous_header: return False prev_hash = hash_header(previous_header) if prev_hash != header.get('prev_block_hash'): return False height = header.get('block_height') bits, target = self.get_target(height / 2016) try: self.verify_header(header, previous_header, bits, target) except: return False return True def connect_chunk(self, idx, hexdata): try: data = hexdata.decode('hex') self.verify_chunk(idx, data) #self.print_error("validated chunk %d" % idx) self.save_chunk(idx, data) return True except BaseException as e: self.print_error('verify_chunk failed', str(e)) return False