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
21 from util import user_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 = [] # monitored transactions
36 self.interface.register_channel('verifier')
37 self.verified_tx = config.get('verified_tx',{})
38 self.merkle_roots = config.get('merkle_roots',{}) # hashed by me
39 self.targets = config.get('targets',{}) # compute targets
40 self.lock = threading.Lock()
41 self.pending_headers = [] # headers that have not been verified
44 self.set_local_height()
46 def get_confirmations(self, tx):
47 """ return the number of confirmations of a monitored transaction. """
49 if tx in self.transactions:
50 return (self.local_height - self.verified_tx[tx] + 1) if tx in self.verified_tx else 0
55 """ add a transaction to the list of monitored transactions. """
57 if tx not in self.transactions:
58 self.transactions.append(tx)
63 requested_headers = []
66 # subscribe to block headers
67 self.interface.send([ ('blockchain.headers.subscribe',[])], 'verifier')
70 # request missing chunks
71 if not all_chunks and self.height and not requested_chunks:
73 if self.local_height + 50 < self.height:
74 min_index = (self.local_height + 1)/2016
75 max_index = (self.height + 1)/2016
76 for i in range(min_index, max_index + 1):
77 # print "requesting chunk", i
78 self.interface.send([ ('blockchain.block.get_chunk',[i])], 'verifier')
79 requested_chunks.append(i)
83 print_error("downloaded all chunks")
85 # request missing tx merkle
86 for tx in self.transactions:
87 if tx not in self.verified_tx:
88 if tx not in requested_merkle:
89 requested_merkle.append(tx)
90 self.request_merkle(tx)
94 # process pending headers
95 if self.pending_headers and all_chunks:
97 for header in self.pending_headers:
98 if self.verify_header(header):
101 # request previous header
102 i = header.get('block_height') - 1
103 if i not in requested_headers:
104 print_error("requesting header %d"%i)
105 self.interface.send([ ('blockchain.block.get_header',[i])], 'verifier')
106 requested_headers.append(i)
107 # no point continuing
109 for header in done: self.pending_headers.remove(header)
110 self.interface.trigger_callback('updated')
113 r = self.interface.get_response('verifier',timeout=1)
123 if method == 'blockchain.transaction.get_merkle':
125 self.verify_merkle(tx_hash, result)
126 requested_merkle.remove(tx_hash)
128 elif method == 'blockchain.block.get_chunk':
130 self.verify_chunk(index, result)
131 requested_chunks.remove(index)
133 elif method in ['blockchain.headers.subscribe', 'blockchain.block.get_header']:
135 self.pending_headers.append(result)
136 if method == 'blockchain.block.get_header':
137 requested_headers.remove(result.get('block_height'))
139 self.height = result.get('block_height')
141 self.pending_headers.sort(key=lambda x: x.get('block_height'))
142 # print "pending headers", map(lambda x: x.get('block_height'), self.pending_headers)
146 self.interface.trigger_callback('updated')
149 def request_merkle(self, tx_hash):
150 self.interface.send([ ('blockchain.transaction.get_merkle',[tx_hash]) ], 'verifier')
153 def verify_merkle(self, tx_hash, result):
154 tx_height = result.get('block_height')
155 self.merkle_roots[tx_hash] = self.hash_merkle_root(result['merkle'], tx_hash, result.get('pos'))
156 header = self.read_header(tx_height)
158 assert header.get('merkle_root') == self.merkle_roots[tx_hash]
159 self.verified_tx[tx_hash] = tx_height
160 print_error("verified %s"%tx_hash)
161 self.config.set_key('verified_tx', self.verified_tx, True)
164 def verify_chunk(self, index, hexdata):
165 data = hexdata.decode('hex')
168 print_error("validating headers %d"%height)
171 previous_hash = ("0"*64)
173 prev_header = self.read_header(index*2016-1)
174 if prev_header is None: raise
175 previous_hash = self.hash_header(prev_header)
177 bits, target = self.get_target(index)
180 height = index*2016 + i
181 raw_header = data[i*80:(i+1)*80]
182 header = self.header_from_string(raw_header)
183 _hash = self.hash_header(header)
184 assert previous_hash == header.get('prev_block_hash')
185 assert bits == header.get('bits')
186 assert eval('0x'+_hash) < target
188 previous_header = header
189 previous_hash = _hash
191 self.save_chunk(index, data)
194 def verify_header(self, header):
195 # add header to the blockchain file
196 # if there is a reorg, push it in a stack
198 height = header.get('block_height')
200 prev_header = self.read_header(height -1)
202 # return False to request previous header
205 prev_hash = self.hash_header(prev_header)
206 bits, target = self.get_target(height/2016)
207 _hash = self.hash_header(header)
209 assert prev_hash == header.get('prev_block_hash')
210 assert bits == header.get('bits')
211 assert eval('0x'+_hash) < target
213 # this can be caused by a reorg.
214 print_error("verify header failed"+ repr(header))
216 for tx_hash, tx_height in self.verified_tx.items():
217 if tx_height >= height:
218 print "redoing", tx_hash
219 self.verified_tx.pop(tx_hash)
220 if tx_hash in self.merkle_roots: self.merkle_roots.pop(tx_hash)
221 # return False to request previous header.
224 self.save_header(header)
225 print_error("verify header:", _hash, height)
231 def header_to_string(self, res):
232 s = int_to_hex(res.get('version'),4) \
233 + rev_hex(res.get('prev_block_hash')) \
234 + rev_hex(res.get('merkle_root')) \
235 + int_to_hex(int(res.get('timestamp')),4) \
236 + int_to_hex(int(res.get('bits')),4) \
237 + int_to_hex(int(res.get('nonce')),4)
241 def header_from_string(self, s):
242 hex_to_int = lambda s: eval('0x' + s[::-1].encode('hex'))
244 h['version'] = hex_to_int(s[0:4])
245 h['prev_block_hash'] = hash_encode(s[4:36])
246 h['merkle_root'] = hash_encode(s[36:68])
247 h['timestamp'] = hex_to_int(s[68:72])
248 h['bits'] = hex_to_int(s[72:76])
249 h['nonce'] = hex_to_int(s[76:80])
252 def hash_header(self, header):
253 return rev_hex(Hash(self.header_to_string(header).decode('hex')).encode('hex'))
255 def hash_merkle_root(self, merkle_s, target_hash, pos):
256 h = hash_decode(target_hash)
257 for i in range(len(merkle_s)):
259 h = Hash( hash_decode(item) + h ) if ((pos >> i) & 1) else Hash( h + hash_decode(item) )
260 return hash_encode(h)
263 wdir = self.config.get('blockchain_headers_path', user_dir())
264 if not os.path.exists( wdir ): os.mkdir(wdir)
265 return os.path.join( wdir, 'blockchain_headers')
267 def save_chunk(self, index, chunk):
268 filename = self.path()
269 if os.path.exists(filename):
270 f = open(filename,'rb+')
272 print "creating file", filename
273 f = open(filename,'wb+')
274 f.seek(index*2016*80)
277 self.set_local_height()
279 def save_header(self, header):
280 data = self.header_to_string(header).decode('hex')
281 assert len(data) == 80
282 height = header.get('block_height')
283 filename = self.path()
284 f = open(filename,'rb+')
288 self.set_local_height()
291 def set_local_height(self):
293 if os.path.exists(name):
294 h = os.path.getsize(name)/80 - 1
295 if self.local_height != h:
296 self.local_height = h
299 def read_header(self, block_height):
301 if os.path.exists(name):
303 f.seek(block_height*80)
307 h = self.header_from_string(h)
311 def get_target(self, index):
313 max_target = 0x00000000FFFF0000000000000000000000000000000000000000000000000000
314 if index == 0: return 0x1d00ffff, max_target
316 first = self.read_header((index-1)*2016)
317 last = self.read_header(index*2016-1)
319 nActualTimespan = last.get('timestamp') - first.get('timestamp')
320 nTargetTimespan = 14*24*60*60
321 nActualTimespan = max(nActualTimespan, nTargetTimespan/4)
322 nActualTimespan = min(nActualTimespan, nTargetTimespan*4)
324 bits = last.get('bits')
330 target = (a) * pow(2, 8 * (bits/MM - 3))
333 new_target = min( max_target, (target * nActualTimespan)/nTargetTimespan )
336 c = ("%064X"%new_target)[2:]
342 c = eval('0x'+c[0:6])
347 new_bits = c + MM * i
348 return new_bits, new_target