#!/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, 0, None)
fdir = os.path.join(config.path, 'forks')
if not os.path.exists(fdir):
os.mkdir(fdir)
l = filter(lambda x: x.startswith('fork_'), os.listdir(fdir))
l = sorted(l, key = lambda x: int(x.split('_')[1]))
for filename in l:
checkpoint = int(filename.split('_')[2])
parent_id = int(filename.split('_')[1])
b = Blockchain(config, checkpoint, parent_id)
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, checkpoint, parent_id):
self.config = config
self.catch_up = None # interface catching up
self.checkpoint = checkpoint
self.parent_id = parent_id
def parent(self):
return blockchains[self.parent_id]
def get_max_child(self):
children = filter(lambda y: y.parent_id==self.checkpoint, blockchains.values())
return max([x.checkpoint for x in children]) if children else None
def get_checkpoint(self):
mc = self.get_max_child()
return mc if mc is not None else self.checkpoint
def get_branch_size(self):
return self.height() - self.get_checkpoint() + 1
def get_name(self):
return self.get_hash(self.get_checkpoint()).lstrip('00')[0:10]
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):
self = Blockchain(parent.config, checkpoint, parent.checkpoint)
# create file
open(self.path(), 'w+').close()
return self
def height(self):
return self.checkpoint + self.size() - 1
def size(self):
p = self.path()
return os.path.getsize(p)/80 if os.path.exists(p) else 0
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)
filename = 'blockchain_headers' if self.parent_id is None else os.path.join('forks', 'fork_%d_%d'%(self.parent_id, self.checkpoint))
return os.path.join(d, filename)
def save_chunk(self, index, chunk):
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)
# order files
if self.parent_id is not None and self.parent().get_branch_size() < self.size():
self.swap_with_parent()
def swap_with_parent(self):
self.print_error("swap", self.checkpoint, self.parent_id)
parent_id = self.parent_id
checkpoint = self.checkpoint
parent = self.parent()
size = parent.get_branch_size()
with open(parent.path(), 'rb+') as f:
f.seek((checkpoint - parent.checkpoint)*80)
parent_data = f.read(size*80)
f.seek((checkpoint - parent.checkpoint)*80)
f.truncate()
with open(self.path(), 'rb+') as f:
my_data = f.read()
f.seek(0)
f.truncate()
f.write(parent_data)
with open(parent.path(), 'rb+') as f:
f.seek((checkpoint - parent.checkpoint)*80)
f.write(my_data)
# store file path
for b in blockchains.values():
b.old_path = b.path()
# swap parameters
self.parent_id = parent.parent_id; parent.parent_id = parent_id
self.checkpoint = parent.checkpoint; parent.checkpoint = checkpoint
# move files
for b in blockchains.values():
if b in [self, parent]: continue
if b.old_path != b.path():
self.print_error("renaming", b.old_path, b.path())
os.rename(b.old_path, b.path())
# update pointers
blockchains[self.checkpoint] = self
blockchains[parent.checkpoint] = parent
def save_header(self, header):
filename = self.path()
delta = header.get('block_height') - self.checkpoint
data = serialize_header(header).decode('hex')
assert delta == self.size()
assert len(data) == 80
with open(filename, 'rb+') as f:
f.seek(delta * 80)
f.write(data)
# order files
if self.parent_id is not None and self.parent().get_branch_size() < self.size():
self.swap_with_parent()
def read_header(self, height):
assert self.parent_id != self.checkpoint
if height < self.checkpoint:
return self.parent().read_header(height)
if height > self.height():
return
delta = height - self.checkpoint
name = self.path()
if os.path.exists(name):
f = open(name, 'rb')
f.seek(delta * 80)
h = f.read(80)
f.close()
return deserialize_header(h, height)
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 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):
height = header['block_height']
if self.height() != height - 1:
return False
if height == 0:
return hash_header(header) == bitcoin.GENESIS
previous_header = self.read_header(height -1)
if not previous_header:
return False
prev_hash = hash_header(previous_header)
if prev_hash != header.get('prev_block_hash'):
return False
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