3 # Electrum - lightweight Bitcoin client
4 # Copyright (C) 2012 thomasv@ecdsa.org
6 # This program is free software: you can redistribute it and/or modify
7 # it under the terms of the GNU General Public License as published by
8 # the Free Software Foundation, either version 3 of the License, or
9 # (at your option) any later version.
11 # This program is distributed in the hope that it will be useful,
12 # but WITHOUT ANY WARRANTY; without even the implied warranty of
13 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 # GNU General Public License for more details.
16 # You should have received a copy of the GNU General Public License
17 # along with this program. If not, see <http://www.gnu.org/licenses/>.
20 import threading, time, Queue, os, sys, shutil
21 from util import user_dir, appdata_dir, print_error
27 class WalletVerifier(threading.Thread):
28 """ Simple Payment Verification """
30 def __init__(self, interface, config):
31 threading.Thread.__init__(self)
34 self.interface = interface
35 self.transactions = {} # requested verifications (with height sent by the requestor)
36 self.interface.register_channel('verifier')
38 self.verified_tx = config.get('verified_tx2',{}) # height, timestamp of verified transactions
39 self.merkle_roots = config.get('merkle_roots',{}) # hashed by me
41 self.targets = config.get('targets',{}) # compute targets
42 self.lock = threading.Lock()
43 self.pending_headers = [] # headers that have not been verified
47 self.headers_url = 'http://images.ecdsa.org/blockchain_headers'
49 def get_confirmations(self, tx):
50 """ return the number of confirmations of a monitored transaction. """
52 if tx in self.transactions.keys():
53 if tx in self.verified_tx:
54 height, timestamp = self.verified_tx[tx]
55 conf = (self.local_height - height + 1)
59 #print "verifier: tx not in list", tx
65 return conf, timestamp
68 def add(self, tx_hash, tx_height):
69 """ add a transaction to the list of monitored transactions. """
72 if tx_hash not in self.transactions.keys():
73 self.transactions[tx_hash] = tx_height
76 with self.lock: self.running = False
77 self.interface.poke('verifier')
80 with self.lock: return self.running
84 self.init_headers_file()
85 self.set_local_height()
91 requested_headers = []
94 # subscribe to block headers
95 self.interface.send([ ('blockchain.headers.subscribe',[])], 'verifier')
97 while self.is_running():
98 # request missing chunks
99 if not all_chunks and self.height and not requested_chunks:
101 if self.local_height + 50 < self.height:
102 min_index = (self.local_height + 1)/2016
103 max_index = (self.height + 1)/2016
104 for i in range(min_index, max_index + 1):
105 print_error( "requesting chunk", i )
106 self.interface.send([ ('blockchain.block.get_chunk',[i])], 'verifier')
107 requested_chunks.append(i)
111 print_error("downloaded all chunks")
115 for tx_hash, tx_height in self.transactions.items():
116 if tx_hash not in self.verified_tx:
117 if self.merkle_roots.get(tx_hash) is None and tx_hash not in requested_merkle:
118 print_error('requesting merkle', tx_hash)
119 self.interface.send([ ('blockchain.transaction.get_merkle',[tx_hash, tx_height]) ], 'verifier')
120 requested_merkle.append(tx_hash)
122 # process pending headers
123 if self.pending_headers and all_chunks:
125 for header in self.pending_headers:
126 if self.verify_header(header):
129 # request previous header
130 i = header.get('block_height') - 1
131 if i not in requested_headers:
132 print_error("requesting header %d"%i)
133 self.interface.send([ ('blockchain.block.get_header',[i])], 'verifier')
134 requested_headers.append(i)
135 # no point continuing
138 self.interface.trigger_callback('updated')
140 self.pending_headers.remove(header)
143 r = self.interface.get_response('verifier',timeout=1)
153 if method == 'blockchain.transaction.get_merkle':
155 self.verify_merkle(tx_hash, result)
156 requested_merkle.remove(tx_hash)
158 elif method == 'blockchain.block.get_chunk':
160 self.verify_chunk(index, result)
161 requested_chunks.remove(index)
163 elif method in ['blockchain.headers.subscribe', 'blockchain.block.get_header']:
165 self.pending_headers.append(result)
166 if method == 'blockchain.block.get_header':
167 requested_headers.remove(result.get('block_height'))
169 self.height = result.get('block_height')
170 self.interface.poke('synchronizer')
172 self.pending_headers.sort(key=lambda x: x.get('block_height'))
173 # print "pending headers", map(lambda x: x.get('block_height'), self.pending_headers)
177 def verify_merkle(self, tx_hash, result):
178 tx_height = result.get('block_height')
179 self.merkle_roots[tx_hash] = self.hash_merkle_root(result['merkle'], tx_hash, result.get('pos'))
180 header = self.read_header(tx_height)
181 if not header: return
182 assert header.get('merkle_root') == self.merkle_roots[tx_hash]
183 # we passed all the tests
184 header = self.read_header(tx_height)
185 timestamp = header.get('timestamp')
186 self.verified_tx[tx_hash] = (tx_height, timestamp)
187 print_error("verified %s"%tx_hash)
188 self.config.set_key('verified_tx2', self.verified_tx, True)
189 self.interface.trigger_callback('updated')
192 def verify_chunk(self, index, hexdata):
193 data = hexdata.decode('hex')
196 print_error("validating headers %d"%height)
199 previous_hash = ("0"*64)
201 prev_header = self.read_header(index*2016-1)
202 if prev_header is None: raise
203 previous_hash = self.hash_header(prev_header)
205 bits, target = self.get_target(index)
208 height = index*2016 + i
209 raw_header = data[i*80:(i+1)*80]
210 header = self.header_from_string(raw_header)
211 _hash = self.hash_header(header)
212 assert previous_hash == header.get('prev_block_hash')
213 assert bits == header.get('bits')
214 assert eval('0x'+_hash) < target
216 previous_header = header
217 previous_hash = _hash
219 self.save_chunk(index, data)
222 def verify_header(self, header):
223 # add header to the blockchain file
224 # if there is a reorg, push it in a stack
226 height = header.get('block_height')
228 prev_header = self.read_header(height -1)
230 # return False to request previous header
233 prev_hash = self.hash_header(prev_header)
234 bits, target = self.get_target(height/2016)
235 _hash = self.hash_header(header)
237 assert prev_hash == header.get('prev_block_hash')
238 assert bits == header.get('bits')
239 assert eval('0x'+_hash) < target
241 # this can be caused by a reorg.
242 print_error("verify header failed"+ repr(header))
244 for tx_hash, item in self.verified_tx.items():
245 tx_height, timestamp = item
246 if tx_height >= height:
247 print_error("redoing", tx_hash)
248 self.verified_tx.pop(tx_hash)
249 if tx_hash in self.merkle_roots: self.merkle_roots.pop(tx_hash)
250 # return False to request previous header.
253 self.save_header(header)
254 print_error("verify header:", _hash, height)
260 def header_to_string(self, res):
261 s = int_to_hex(res.get('version'),4) \
262 + rev_hex(res.get('prev_block_hash')) \
263 + rev_hex(res.get('merkle_root')) \
264 + int_to_hex(int(res.get('timestamp')),4) \
265 + int_to_hex(int(res.get('bits')),4) \
266 + int_to_hex(int(res.get('nonce')),4)
270 def header_from_string(self, s):
271 hex_to_int = lambda s: eval('0x' + s[::-1].encode('hex'))
273 h['version'] = hex_to_int(s[0:4])
274 h['prev_block_hash'] = hash_encode(s[4:36])
275 h['merkle_root'] = hash_encode(s[36:68])
276 h['timestamp'] = hex_to_int(s[68:72])
277 h['bits'] = hex_to_int(s[72:76])
278 h['nonce'] = hex_to_int(s[76:80])
281 def hash_header(self, header):
282 return rev_hex(Hash(self.header_to_string(header).decode('hex')).encode('hex'))
284 def hash_merkle_root(self, merkle_s, target_hash, pos):
285 h = hash_decode(target_hash)
286 for i in range(len(merkle_s)):
288 h = Hash( hash_decode(item) + h ) if ((pos >> i) & 1) else Hash( h + hash_decode(item) )
289 return hash_encode(h)
292 wdir = self.config.get('blockchain_headers_path', user_dir())
293 if wdir and not os.path.exists( wdir ): os.mkdir(wdir)
294 return os.path.join( wdir, 'blockchain_headers')
296 def init_headers_file(self):
297 filename = self.path()
298 if os.path.exists(filename):
302 import urllib, socket
303 socket.setdefaulttimeout(30)
304 print_error("downloading ", self.headers_url )
305 urllib.urlretrieve(self.headers_url, filename)
307 print_error( "download failed. creating file", filename )
308 open(filename,'wb+').close()
310 def save_chunk(self, index, chunk):
311 filename = self.path()
312 f = open(filename,'rb+')
313 f.seek(index*2016*80)
316 self.set_local_height()
318 def save_header(self, header):
319 data = self.header_to_string(header).decode('hex')
320 assert len(data) == 80
321 height = header.get('block_height')
322 filename = self.path()
323 f = open(filename,'rb+')
327 self.set_local_height()
330 def set_local_height(self):
332 if os.path.exists(name):
333 h = os.path.getsize(name)/80 - 1
334 if self.local_height != h:
335 self.local_height = h
338 def read_header(self, block_height):
340 if os.path.exists(name):
342 f.seek(block_height*80)
346 h = self.header_from_string(h)
350 def get_target(self, index):
352 max_target = 0x00000000FFFF0000000000000000000000000000000000000000000000000000
353 if index == 0: return 0x1d00ffff, max_target
355 first = self.read_header((index-1)*2016)
356 last = self.read_header(index*2016-1)
358 nActualTimespan = last.get('timestamp') - first.get('timestamp')
359 nTargetTimespan = 14*24*60*60
360 nActualTimespan = max(nActualTimespan, nTargetTimespan/4)
361 nActualTimespan = min(nActualTimespan, nTargetTimespan*4)
363 bits = last.get('bits')
369 target = (a) * pow(2, 8 * (bits/MM - 3))
372 new_target = min( max_target, (target * nActualTimespan)/nTargetTimespan )
375 c = ("%064X"%new_target)[2:]
381 c = eval('0x'+c[0:6])
386 new_bits = c + MM * i
387 return new_bits, new_target