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
27 class WalletVerifier(threading.Thread):
29 def __init__(self, interface, config, get_transactions):
30 threading.Thread.__init__(self)
33 self.interface = interface
34 self.get_transactions = get_transactions
35 self.interface.register_channel('verifier')
36 self.verified_tx = config.get('verified_tx',[])
37 self.merkle_roots = config.get('merkle_roots',{}) # hashed by me
38 self.targets = config.get('targets',{}) # compute targets
39 self.lock = threading.Lock()
40 self.pending_headers = [] # headers that have not been verified
43 self.set_local_numblocks()
51 requested_headers = []
52 pending_headers_changed = False
54 # subscribe to block headers
55 self.interface.send([ ('blockchain.headers.subscribe',[])], 'verifier')
58 # request missing chunks
59 max_index = (self.height+1)/2016
60 if not requested_chunks:
61 for i in range(0, max_index + 1):
62 # test if we can read the first header of the chunk
63 if self.read_header(i*2016): continue
64 print "requesting chunk", i
65 self.interface.send([ ('blockchain.block.get_chunk',[i])], 'verifier')
66 requested_chunks.append(i)
69 # request missing headers
70 if not requested_chunks and self.local_height:
71 for i in range(self.local_height + 1, self.height + 1):
72 if i not in requested_headers:
73 print "requesting header", i
74 self.interface.send([ ('blockchain.block.get_header',[i])], 'verifier')
75 requested_headers.append(i)
77 # request missing tx merkle
78 txlist = self.get_transactions()
80 if tx not in self.verified_tx:
81 if tx not in requested_merkle:
82 requested_merkle.append(tx)
83 self.request_merkle(tx)
87 r = self.interface.get_response('verifier',timeout=1)
97 if method == 'blockchain.transaction.get_merkle':
99 self.verify_merkle(tx_hash, result)
100 requested_merkle.remove(tx_hash)
102 elif method == 'blockchain.block.get_chunk':
104 self.verify_chunk(index, result)
105 requested_chunks.remove(index)
107 elif method == 'blockchain.headers.subscribe':
108 self.height = result.get('block_height')
109 self.pending_headers.append(result)
110 pending_headers_changed = True
112 elif method == 'blockchain.block.get_header':
113 height = result.get('block_height')
114 requested_headers.remove(height)
115 self.pending_headers.append(result)
116 pending_headers_changed = True
118 # process pending headers
119 if pending_headers_changed:
120 self.pending_headers.sort(key=lambda x: x.get('block_height'))
121 print "pending headers", map(lambda x: x.get('block_height'), self.pending_headers)
122 for header in self.pending_headers:
123 if self.verify_header(header):
124 self.pending_headers.remove(header)
127 pending_headers_changed = False
131 def request_merkle(self, tx_hash):
132 self.interface.send([ ('blockchain.transaction.get_merkle',[tx_hash]) ], 'verifier')
135 def verify_merkle(self, tx_hash, result):
136 tx_height = result.get('block_height')
137 self.merkle_roots[tx_hash] = self.hash_merkle_root(result['merkle'], tx_hash)
138 header = self.read_header(tx_height)
140 assert header.get('merkle_root') == self.merkle_roots[tx_hash]
141 self.verified_tx.append(tx_hash)
142 print "verified", tx_hash
143 self.config.set_key('verified_tx', self.verified_tx, True)
146 def verify_chunk(self, index, hexdata):
147 data = hexdata.decode('hex')
150 print "validate_chunk", index, num
153 previous_hash = ("0"*64)
155 prev_header = self.read_header(index*2016-1)
156 if prev_header is None: raise
157 previous_hash = self.hash_header(prev_header)
159 bits, target = self.get_target(index)
162 height = index*2016 + i
163 raw_header = data[i*80:(i+1)*80]
164 header = self.header_from_string(raw_header)
165 _hash = self.hash_header(header)
166 assert previous_hash == header.get('prev_block_hash')
167 assert bits == header.get('bits')
168 assert eval('0x'+_hash) < target
170 previous_header = header
171 previous_hash = _hash
173 self.save_chunk(index, data)
176 def verify_header(self, header):
177 # add header to the blockchain file
178 # if there is a reorg, push it in a stack
180 height = header.get('block_height')
182 prev_header = self.read_header(height -1)
184 print "no previous header", height
187 #prev_hash = prev_header.get('block_height')
188 prev_hash = self.hash_header(prev_header)
189 bits, target = self.get_target(height/2016)
190 _hash = self.hash_header(header)
192 assert prev_hash == header.get('prev_block_hash')
193 assert bits == header.get('bits')
194 assert eval('0x'+_hash) < target
197 print "verify header failed", header
199 # this could be caused by a reorg. request the previous header
201 #request previous one
204 self.save_header(header)
205 print "verify header: ok", height
211 def header_to_string(self, res):
212 s = int_to_hex(res.get('version'),4) \
213 + rev_hex(res.get('prev_block_hash')) \
214 + rev_hex(res.get('merkle_root')) \
215 + int_to_hex(int(res.get('timestamp')),4) \
216 + int_to_hex(int(res.get('bits')),4) \
217 + int_to_hex(int(res.get('nonce')),4)
221 def header_from_string(self, s):
222 hex_to_int = lambda s: eval('0x' + s[::-1].encode('hex'))
224 h['version'] = hex_to_int(s[0:4])
225 h['prev_block_hash'] = hash_encode(s[4:36])
226 h['merkle_root'] = hash_encode(s[36:68])
227 h['timestamp'] = hex_to_int(s[68:72])
228 h['bits'] = hex_to_int(s[72:76])
229 h['nonce'] = hex_to_int(s[76:80])
233 def hash_header(self, header):
234 return rev_hex(Hash(self.header_to_string(header).decode('hex')).encode('hex'))
237 def hash_merkle_root(self, merkle_s, target_hash):
238 h = hash_decode(target_hash)
239 for item in merkle_s:
240 is_left = item[0] == 'L'
241 h = Hash( h + hash_decode(item[1:]) ) if is_left else Hash( hash_decode(item[1:]) + h )
242 return hash_encode(h)
246 if not os.path.exists( wdir ):
247 wdir = os.path.dirname(self.config.path)
248 return os.path.join( wdir, 'blockchain_headers')
250 def save_chunk(self, index, chunk):
251 filename = self.path()
252 if os.path.exists(filename):
253 f = open(filename,'rw+')
255 print "creating file", filename
256 f = open(filename,'w+')
257 f.seek(index*2016*80)
260 self.set_local_numblocks()
262 def save_header(self, header):
263 data = self.header_to_string(header).decode('hex')
264 assert len(data) == 80
265 height = header.get('block_height')
266 filename = self.path()
267 f = open(filename,'rw+')
271 self.set_local_numblocks()
273 def set_local_numblocks(self):
275 if os.path.exists(name):
276 self.local_height = os.path.getsize(name)/80 - 1
277 # print "local height", self.local_height, os.path.getsize(name)/80.
280 def read_header(self, block_height):
282 if os.path.exists(name):
284 f.seek(block_height*80)
288 h = self.header_from_string(h)
292 def get_target(self, index):
294 max_target = 0x00000000FFFF0000000000000000000000000000000000000000000000000000
295 if index == 0: return 0x1d00ffff, max_target
297 first = self.read_header((index-1)*2016)
298 last = self.read_header(index*2016-1)
300 nActualTimespan = last.get('timestamp') - first.get('timestamp')
301 nTargetTimespan = 14*24*60*60
302 nActualTimespan = max(nActualTimespan, nTargetTimespan/4)
303 nActualTimespan = min(nActualTimespan, nTargetTimespan*4)
305 bits = last.get('bits')
311 target = (a) * pow(2, 8 * (bits/MM - 3))
314 new_target = min( max_target, (target * nActualTimespan)/nTargetTimespan )
317 c = ("%064X"%new_target)[2:]
323 c = eval('0x'+c[0:6])
328 new_bits = c + MM * i
329 # print "%3d"%index, "%8x"%bits, "%64X"%new_target, hex(c)[2:].upper(), hex(new_bits)
330 return new_bits, new_target