You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
239 lines
8.9 KiB
239 lines
8.9 KiB
#!/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 |
|
|
|
class Blockchain(util.PrintError): |
|
'''Manages blockchain headers and their verification''' |
|
def __init__(self, config, network): |
|
self.config = config |
|
self.network = network |
|
self.local_height = 0 |
|
self.set_local_height() |
|
|
|
def height(self): |
|
return self.local_height |
|
|
|
def init(self): |
|
import threading |
|
if os.path.exists(self.path()): |
|
self.downloading_headers = False |
|
return |
|
self.downloading_headers = True |
|
t = threading.Thread(target = self.init_headers_file) |
|
t.daemon = True |
|
t.start() |
|
|
|
def verify_header(self, header, prev_header, bits, target): |
|
prev_hash = self.hash_header(prev_header) |
|
assert prev_hash == header.get('prev_block_hash'), "prev hash mismatch: %s vs %s" % (prev_hash, header.get('prev_block_hash')) |
|
if bitcoin.TESTNET: return |
|
assert bits == header.get('bits'), "bits mismatch: %s vs %s" % (bits, header.get('bits')) |
|
_hash = self.hash_header(header) |
|
assert int('0x' + _hash, 16) <= target, "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 = self.deserialize_header(raw_header) |
|
self.verify_header(header, prev_header, bits, target) |
|
prev_header = header |
|
|
|
def serialize_header(self, 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(self, s): |
|
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]) |
|
return h |
|
|
|
def hash_header(self, header): |
|
if header is None: |
|
return '0' * 64 |
|
return hash_encode(Hash(self.serialize_header(header).decode('hex'))) |
|
|
|
def path(self): |
|
return util.get_headers_path(self.config) |
|
|
|
def init_headers_file(self): |
|
filename = self.path() |
|
try: |
|
import urllib, socket |
|
socket.setdefaulttimeout(30) |
|
self.print_error("downloading ", bitcoin.HEADERS_URL) |
|
urllib.urlretrieve(bitcoin.HEADERS_URL, filename + '.tmp') |
|
os.rename(filename + '.tmp', filename) |
|
self.print_error("done.") |
|
except Exception: |
|
self.print_error("download failed. creating file", filename) |
|
open(filename, 'wb+').close() |
|
self.downloading_headers = False |
|
self.set_local_height() |
|
self.print_error("%d blocks" % self.local_height) |
|
|
|
def save_chunk(self, index, chunk): |
|
filename = self.path() |
|
f = open(filename, 'rb+') |
|
f.seek(index * 2016 * 80) |
|
h = f.write(chunk) |
|
f.close() |
|
self.set_local_height() |
|
|
|
def save_header(self, header): |
|
data = self.serialize_header(header).decode('hex') |
|
assert len(data) == 80 |
|
height = header.get('block_height') |
|
filename = self.path() |
|
f = open(filename, 'rb+') |
|
f.seek(height * 80) |
|
h = f.write(data) |
|
f.close() |
|
self.set_local_height() |
|
|
|
def set_local_height(self): |
|
name = self.path() |
|
if os.path.exists(name): |
|
h = os.path.getsize(name)/80 - 1 |
|
if self.local_height != h: |
|
self.local_height = h |
|
|
|
def read_header(self, block_height): |
|
name = self.path() |
|
if os.path.exists(name): |
|
f = open(name, 'rb') |
|
f.seek(block_height * 80) |
|
h = f.read(80) |
|
f.close() |
|
if len(h) == 80: |
|
h = self.deserialize_header(h) |
|
return h |
|
|
|
def get_target(self, index, chain=None): |
|
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 |
|
assert bitsN >= 0x03 and bitsN <= 0x1d, "First part of bits should be in [0x03, 0x1d]" |
|
bitsBase = bits & 0xffffff |
|
assert bitsBase >= 0x8000 and bitsBase <= 0x7fffff, "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 connect_header(self, chain, header): |
|
'''Builds a header chain until it connects. Returns True if it has |
|
successfully connected, False if verification failed, otherwise the |
|
height of the next header needed.''' |
|
chain.append(header) # Ordered by decreasing height |
|
previous_height = header['block_height'] - 1 |
|
previous_header = self.read_header(previous_height) |
|
|
|
# Missing header, request it |
|
if not previous_header: |
|
return previous_height |
|
|
|
# Does it connect to my chain? |
|
prev_hash = self.hash_header(previous_header) |
|
if prev_hash != header.get('prev_block_hash'): |
|
self.print_error("reorg") |
|
return previous_height |
|
|
|
# The chain is complete. Reverse to order by increasing height |
|
chain.reverse() |
|
try: |
|
self.verify_chain(chain) |
|
self.print_error("new height:", previous_height + len(chain)) |
|
for header in chain: |
|
self.save_header(header) |
|
return True |
|
except BaseException as e: |
|
self.print_error(str(e)) |
|
return False |
|
|
|
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 idx + 1 |
|
except BaseException as e: |
|
self.print_error('verify_chunk failed', str(e)) |
|
return idx - 1
|
|
|