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419 lines
14 KiB
419 lines
14 KiB
#!/usr/bin/env python
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#
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# Electrum - lightweight Bitcoin client
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# Copyright (C) 2012 thomasv@ecdsa.org
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#
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# This program is free software: you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation, either version 3 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program. If not, see <http://www.gnu.org/licenses/>.
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import threading, time, Queue, os, sys, shutil
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from util import user_dir, appdata_dir, print_error
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from bitcoin import *
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class WalletVerifier(threading.Thread):
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""" Simple Payment Verification """
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def __init__(self, interface, config):
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threading.Thread.__init__(self)
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self.daemon = True
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self.config = config
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self.interface = interface
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self.transactions = {} # requested verifications (with height sent by the requestor)
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self.interface.register_channel('verifier')
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self.verified_tx = config.get('verified_tx3',{}) # height, timestamp of verified transactions
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self.merkle_roots = config.get('merkle_roots',{}) # hashed by me
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self.targets = config.get('targets',{}) # compute targets
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self.lock = threading.Lock()
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self.pending_headers = [] # headers that have not been verified
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self.height = 0
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self.local_height = 0
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self.running = False
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self.headers_url = 'http://headers.electrum.org/blockchain_headers'
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def get_confirmations(self, tx):
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""" return the number of confirmations of a monitored transaction. """
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with self.lock:
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if tx in self.verified_tx:
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height, timestamp, pos = self.verified_tx[tx]
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conf = (self.local_height - height + 1)
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if conf <= 0: timestamp = None
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elif tx in self.transactions:
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conf = -1
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timestamp = None
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else:
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conf = 0
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timestamp = None
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return conf, timestamp
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def get_txpos(self, tx_hash):
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"return position, even if the tx is unverified"
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with self.lock:
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x = self.verified_tx.get(tx_hash)
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y = self.transactions.get(tx_hash)
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if x:
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height, timestamp, pos = x
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return height, pos
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elif y:
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return y, 0
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else:
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return 1e12, 0
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def get_height(self, tx_hash):
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with self.lock:
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v = self.verified_tx.get(tx_hash)
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height = v[0] if v else None
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return height
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def add(self, tx_hash, tx_height):
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""" add a transaction to the list of monitored transactions. """
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assert tx_height > 0
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with self.lock:
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if tx_hash not in self.transactions.keys():
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self.transactions[tx_hash] = tx_height
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def stop(self):
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with self.lock: self.running = False
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self.interface.poke('verifier')
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def is_running(self):
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with self.lock: return self.running
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def run(self):
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self.init_headers_file()
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self.set_local_height()
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with self.lock:
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self.running = True
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requested_merkle = []
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requested_chunks = []
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requested_headers = []
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all_chunks = False
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# subscribe to block headers
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self.interface.send([ ('blockchain.headers.subscribe',[])], 'verifier')
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while self.is_running():
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# request missing chunks
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if not all_chunks and self.height and not requested_chunks:
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if self.local_height + 50 < self.height:
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min_index = (self.local_height + 1)/2016
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max_index = (self.height + 1)/2016
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for i in range(min_index, max_index + 1):
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print_error( "requesting chunk", i )
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self.interface.send([ ('blockchain.block.get_chunk',[i])], 'verifier')
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requested_chunks.append(i)
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break
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else:
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all_chunks = True
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print_error("downloaded all chunks")
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# request missing tx
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if all_chunks:
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for tx_hash, tx_height in self.transactions.items():
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if tx_hash not in self.verified_tx:
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if self.merkle_roots.get(tx_hash) is None and tx_hash not in requested_merkle:
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print_error('requesting merkle', tx_hash)
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self.interface.send([ ('blockchain.transaction.get_merkle',[tx_hash, tx_height]) ], 'verifier')
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requested_merkle.append(tx_hash)
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# process pending headers
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if self.pending_headers and all_chunks:
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done = []
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for header in self.pending_headers:
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if self.verify_header(header):
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done.append(header)
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else:
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# request previous header
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i = header.get('block_height') - 1
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if i not in requested_headers:
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print_error("requesting header %d"%i)
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self.interface.send([ ('blockchain.block.get_header',[i])], 'verifier')
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requested_headers.append(i)
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# no point continuing
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break
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if done:
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self.interface.trigger_callback('updated')
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for header in done:
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self.pending_headers.remove(header)
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try:
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r = self.interface.get_response('verifier',timeout=1)
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except Queue.Empty:
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continue
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if not r: continue
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if r.get('error'):
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print_error('Verifier received an error:', r)
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continue
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# 3. handle response
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method = r['method']
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params = r['params']
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result = r['result']
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if method == 'blockchain.transaction.get_merkle':
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tx_hash = params[0]
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self.verify_merkle(tx_hash, result)
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requested_merkle.remove(tx_hash)
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elif method == 'blockchain.block.get_chunk':
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index = params[0]
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self.verify_chunk(index, result)
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requested_chunks.remove(index)
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elif method in ['blockchain.headers.subscribe', 'blockchain.block.get_header']:
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self.pending_headers.append(result)
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if method == 'blockchain.block.get_header':
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requested_headers.remove(result.get('block_height'))
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else:
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self.height = result.get('block_height')
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self.interface.poke('synchronizer')
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self.pending_headers.sort(key=lambda x: x.get('block_height'))
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# print "pending headers", map(lambda x: x.get('block_height'), self.pending_headers)
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def verify_merkle(self, tx_hash, result):
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tx_height = result.get('block_height')
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pos = result.get('pos')
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self.merkle_roots[tx_hash] = self.hash_merkle_root(result['merkle'], tx_hash, pos)
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header = self.read_header(tx_height)
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if not header: return
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assert header.get('merkle_root') == self.merkle_roots[tx_hash]
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# we passed all the tests
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header = self.read_header(tx_height)
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timestamp = header.get('timestamp')
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with self.lock:
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self.verified_tx[tx_hash] = (tx_height, timestamp, pos)
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print_error("verified %s"%tx_hash)
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self.config.set_key('verified_tx3', self.verified_tx, True)
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self.interface.trigger_callback('updated')
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def verify_chunk(self, index, hexdata):
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data = hexdata.decode('hex')
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height = index*2016
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num = len(data)/80
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print_error("validating headers %d"%height)
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if index == 0:
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previous_hash = ("0"*64)
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else:
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prev_header = self.read_header(index*2016-1)
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if prev_header is None: raise
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previous_hash = self.hash_header(prev_header)
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bits, target = self.get_target(index)
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for i in range(num):
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height = index*2016 + i
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raw_header = data[i*80:(i+1)*80]
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header = self.header_from_string(raw_header)
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_hash = self.hash_header(header)
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assert previous_hash == header.get('prev_block_hash')
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assert bits == header.get('bits')
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assert eval('0x'+_hash) < target
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previous_header = header
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previous_hash = _hash
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self.save_chunk(index, data)
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def verify_header(self, header):
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# add header to the blockchain file
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# if there is a reorg, push it in a stack
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height = header.get('block_height')
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prev_header = self.read_header(height -1)
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if not prev_header:
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# return False to request previous header
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return False
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prev_hash = self.hash_header(prev_header)
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bits, target = self.get_target(height/2016)
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_hash = self.hash_header(header)
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try:
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assert prev_hash == header.get('prev_block_hash')
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assert bits == header.get('bits')
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assert eval('0x'+_hash) < target
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except:
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# this can be caused by a reorg.
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print_error("verify header failed"+ repr(header))
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# undo verifications
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with self.lock:
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items = self.verified_tx.items()[:]
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for tx_hash, item in items:
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tx_height, timestamp, pos = item
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if tx_height >= height:
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print_error("redoing", tx_hash)
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with self.lock:
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self.verified_tx.pop(tx_hash)
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if tx_hash in self.merkle_roots:
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self.merkle_roots.pop(tx_hash)
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# return False to request previous header.
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return False
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self.save_header(header)
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print_error("verify header:", _hash, height)
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return True
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def header_to_string(self, 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 header_from_string(self, s):
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hex_to_int = lambda s: eval('0x' + s[::-1].encode('hex'))
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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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return h
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def hash_header(self, header):
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return rev_hex(Hash(self.header_to_string(header).decode('hex')).encode('hex'))
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def hash_merkle_root(self, merkle_s, target_hash, pos):
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h = hash_decode(target_hash)
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for i in range(len(merkle_s)):
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item = merkle_s[i]
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h = Hash( hash_decode(item) + h ) if ((pos >> i) & 1) else Hash( h + hash_decode(item) )
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return hash_encode(h)
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def path(self):
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wdir = self.config.get('blockchain_headers_path', user_dir())
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if wdir and not os.path.exists( wdir ): os.mkdir(wdir)
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return os.path.join( wdir, 'blockchain_headers')
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def init_headers_file(self):
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filename = self.path()
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if os.path.exists(filename):
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return
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try:
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import urllib, socket
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socket.setdefaulttimeout(30)
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print_error("downloading ", self.headers_url )
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urllib.urlretrieve(self.headers_url, filename)
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except:
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print_error( "download failed. creating file", filename )
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open(filename,'wb+').close()
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def save_chunk(self, index, chunk):
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filename = self.path()
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f = open(filename,'rb+')
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f.seek(index*2016*80)
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h = f.write(chunk)
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f.close()
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self.set_local_height()
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def save_header(self, header):
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data = self.header_to_string(header).decode('hex')
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assert len(data) == 80
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height = header.get('block_height')
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filename = self.path()
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f = open(filename,'rb+')
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f.seek(height*80)
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h = f.write(data)
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f.close()
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self.set_local_height()
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def set_local_height(self):
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name = self.path()
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if os.path.exists(name):
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h = os.path.getsize(name)/80 - 1
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if self.local_height != h:
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self.local_height = h
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def read_header(self, block_height):
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name = self.path()
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if os.path.exists(name):
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f = open(name,'rb')
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f.seek(block_height*80)
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h = f.read(80)
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f.close()
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if len(h) == 80:
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h = self.header_from_string(h)
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return h
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def get_target(self, index):
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max_target = 0x00000000FFFF0000000000000000000000000000000000000000000000000000
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if index == 0: return 0x1d00ffff, max_target
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first = self.read_header((index-1)*2016)
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last = self.read_header(index*2016-1)
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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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bits = last.get('bits')
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# convert to bignum
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MM = 256*256*256
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a = bits%MM
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if a < 0x8000:
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a *= 256
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target = (a) * pow(2, 8 * (bits/MM - 3))
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# new target
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new_target = min( max_target, (target * nActualTimespan)/nTargetTimespan )
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# convert it to bits
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c = ("%064X"%new_target)[2:]
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i = 31
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while c[0:2]=="00":
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c = c[2:]
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i -= 1
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c = eval('0x'+c[0:6])
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if c > 0x800000:
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c /= 256
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i += 1
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new_bits = c + MM * i
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return new_bits, new_target
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