#!/usr/bin/env python
#
# Electrum - lightweight Bitcoin client
# Copyright (C) 2012 thomasv@ecdsa.org
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
import threading, time, Queue, os, sys, shutil
from util import user_dir, appdata_dir, print_error
from bitcoin import *
class WalletVerifier(threading.Thread):
""" Simple Payment Verification """
def __init__(self, interface, config):
threading.Thread.__init__(self)
self.daemon = True
self.config = config
self.interface = interface
self.transactions = {} # requested verifications (with height sent by the requestor)
self.interface.register_channel('verifier')
self.verified_tx = config.get('verified_tx2',{}) # height, timestamp of verified transactions
self.merkle_roots = config.get('merkle_roots',{}) # hashed by me
self.targets = config.get('targets',{}) # compute targets
self.lock = threading.Lock()
self.pending_headers = [] # headers that have not been verified
self.height = 0
self.local_height = 0
self.running = False
self.headers_url = 'http://headers.electrum.org/blockchain_headers'
def get_confirmations(self, tx):
""" return the number of confirmations of a monitored transaction. """
with self.lock:
if tx in self.transactions.keys():
if tx in self.verified_tx:
height, timestamp = self.verified_tx[tx]
conf = (self.local_height - height + 1)
else:
conf = -1
else:
#print "verifier: tx not in list", tx
conf = 0
if conf <= 0:
timestamp = None
return conf, timestamp
def add(self, tx_hash, tx_height):
""" add a transaction to the list of monitored transactions. """
assert tx_height > 0
with self.lock:
if tx_hash not in self.transactions.keys():
self.transactions[tx_hash] = tx_height
def stop(self):
with self.lock: self.running = False
self.interface.poke('verifier')
def is_running(self):
with self.lock: return self.running
def run(self):
self.init_headers_file()
self.set_local_height()
with self.lock:
self.running = True
requested_merkle = []
requested_chunks = []
requested_headers = []
all_chunks = False
# subscribe to block headers
self.interface.send([ ('blockchain.headers.subscribe',[])], 'verifier')
while self.is_running():
# request missing chunks
if not all_chunks and self.height and not requested_chunks:
if self.local_height + 50 < self.height:
min_index = (self.local_height + 1)/2016
max_index = (self.height + 1)/2016
for i in range(min_index, max_index + 1):
print_error( "requesting chunk", i )
self.interface.send([ ('blockchain.block.get_chunk',[i])], 'verifier')
requested_chunks.append(i)
break
else:
all_chunks = True
print_error("downloaded all chunks")
# request missing tx
if all_chunks:
for tx_hash, tx_height in self.transactions.items():
if tx_hash not in self.verified_tx:
if self.merkle_roots.get(tx_hash) is None and tx_hash not in requested_merkle:
print_error('requesting merkle', tx_hash)
self.interface.send([ ('blockchain.transaction.get_merkle',[tx_hash, tx_height]) ], 'verifier')
requested_merkle.append(tx_hash)
# process pending headers
if self.pending_headers and all_chunks:
done = []
for header in self.pending_headers:
if self.verify_header(header):
done.append(header)
else:
# request previous header
i = header.get('block_height') - 1
if i not in requested_headers:
print_error("requesting header %d"%i)
self.interface.send([ ('blockchain.block.get_header',[i])], 'verifier')
requested_headers.append(i)
# no point continuing
break
if done:
self.interface.trigger_callback('updated')
for header in done:
self.pending_headers.remove(header)
try:
r = self.interface.get_response('verifier',timeout=1)
except Queue.Empty:
continue
if not r: continue
# 3. handle response
method = r['method']
params = r['params']
result = r['result']
if method == 'blockchain.transaction.get_merkle':
tx_hash = params[0]
self.verify_merkle(tx_hash, result)
requested_merkle.remove(tx_hash)
elif method == 'blockchain.block.get_chunk':
index = params[0]
self.verify_chunk(index, result)
requested_chunks.remove(index)
elif method in ['blockchain.headers.subscribe', 'blockchain.block.get_header']:
self.pending_headers.append(result)
if method == 'blockchain.block.get_header':
requested_headers.remove(result.get('block_height'))
else:
self.height = result.get('block_height')
self.interface.poke('synchronizer')
self.pending_headers.sort(key=lambda x: x.get('block_height'))
# print "pending headers", map(lambda x: x.get('block_height'), self.pending_headers)
def verify_merkle(self, tx_hash, result):
tx_height = result.get('block_height')
self.merkle_roots[tx_hash] = self.hash_merkle_root(result['merkle'], tx_hash, result.get('pos'))
header = self.read_header(tx_height)
if not header: return
assert header.get('merkle_root') == self.merkle_roots[tx_hash]
# we passed all the tests
header = self.read_header(tx_height)
timestamp = header.get('timestamp')
self.verified_tx[tx_hash] = (tx_height, timestamp)
print_error("verified %s"%tx_hash)
self.config.set_key('verified_tx2', self.verified_tx, True)
self.interface.trigger_callback('updated')
def verify_chunk(self, index, hexdata):
data = hexdata.decode('hex')
height = index*2016
num = len(data)/80
print_error("validating headers %d"%height)
if index == 0:
previous_hash = ("0"*64)
else:
prev_header = self.read_header(index*2016-1)
if prev_header is None: raise
previous_hash = self.hash_header(prev_header)
bits, target = self.get_target(index)
for i in range(num):
height = index*2016 + i
raw_header = data[i*80:(i+1)*80]
header = self.header_from_string(raw_header)
_hash = self.hash_header(header)
assert previous_hash == header.get('prev_block_hash')
assert bits == header.get('bits')
assert eval('0x'+_hash) < target
previous_header = header
previous_hash = _hash
self.save_chunk(index, data)
def verify_header(self, header):
# add header to the blockchain file
# if there is a reorg, push it in a stack
height = header.get('block_height')
prev_header = self.read_header(height -1)
if not prev_header:
# return False to request previous header
return False
prev_hash = self.hash_header(prev_header)
bits, target = self.get_target(height/2016)
_hash = self.hash_header(header)
try:
assert prev_hash == header.get('prev_block_hash')
assert bits == header.get('bits')
assert eval('0x'+_hash) < target
except:
# this can be caused by a reorg.
print_error("verify header failed"+ repr(header))
# undo verifications
for tx_hash, item in self.verified_tx.items():
tx_height, timestamp = item
if tx_height >= height:
print_error("redoing", tx_hash)
self.verified_tx.pop(tx_hash)
if tx_hash in self.merkle_roots: self.merkle_roots.pop(tx_hash)
# return False to request previous header.
return False
self.save_header(header)
print_error("verify header:", _hash, height)
return True
def header_to_string(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 header_from_string(self, s):
hex_to_int = lambda s: eval('0x' + s[::-1].encode('hex'))
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):
return rev_hex(Hash(self.header_to_string(header).decode('hex')).encode('hex'))
def hash_merkle_root(self, merkle_s, target_hash, pos):
h = hash_decode(target_hash)
for i in range(len(merkle_s)):
item = merkle_s[i]
h = Hash( hash_decode(item) + h ) if ((pos >> i) & 1) else Hash( h + hash_decode(item) )
return hash_encode(h)
def path(self):
wdir = self.config.get('blockchain_headers_path', user_dir())
if wdir and not os.path.exists( wdir ): os.mkdir(wdir)
return os.path.join( wdir, 'blockchain_headers')
def init_headers_file(self):
filename = self.path()
if os.path.exists(filename):
return
try:
import urllib, socket
socket.setdefaulttimeout(30)
print_error("downloading ", self.headers_url )
urllib.urlretrieve(self.headers_url, filename)
except:
print_error( "download failed. creating file", filename )
open(filename,'wb+').close()
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.header_to_string(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.header_from_string(h)
return h
def get_target(self, index):
max_target = 0x00000000FFFF0000000000000000000000000000000000000000000000000000
if index == 0: return 0x1d00ffff, max_target
first = self.read_header((index-1)*2016)
last = self.read_header(index*2016-1)
nActualTimespan = last.get('timestamp') - first.get('timestamp')
nTargetTimespan = 14*24*60*60
nActualTimespan = max(nActualTimespan, nTargetTimespan/4)
nActualTimespan = min(nActualTimespan, nTargetTimespan*4)
bits = last.get('bits')
# convert to bignum
MM = 256*256*256
a = bits%MM
if a < 0x8000:
a *= 256
target = (a) * pow(2, 8 * (bits/MM - 3))
# new target
new_target = min( max_target, (target * nActualTimespan)/nTargetTimespan )
# convert it to bits
c = ("%064X"%new_target)[2:]
i = 31
while c[0:2]=="00":
c = c[2:]
i -= 1
c = eval('0x'+c[0:6])
if c > 0x800000:
c /= 256
i += 1
new_bits = c + MM * i
return new_bits, new_target