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
25 from ltc_scrypt import getPoWHash
27 print_msg("Warning: scrypt not available, using fallback")
28 from scrypt import scrypt_1024_1_1_80 as getPoWHash
30 class Blockchain(threading.Thread):
32 def __init__(self, config, network):
33 threading.Thread.__init__(self)
36 self.network = network
37 self.lock = threading.Lock()
40 self.headers_url = 'http://novacoin.su/static/blockchain_headers'
41 self.set_local_height()
42 self.queue = Queue.Queue()
46 return self.local_height
50 with self.lock: self.running = False
54 with self.lock: return self.running
58 self.init_headers_file()
59 self.set_local_height()
60 print_error( "blocks:", self.local_height )
65 while self.is_running():
68 result = self.queue.get()
72 if not result: continue
75 if not header: continue
77 height = header.get('block_height')
79 if height <= self.local_height:
82 if height > self.local_height + 50:
83 if not self.get_and_verify_chunks(i, header, height):
86 if height > self.local_height:
87 # get missing parts from interface (until it connects to my chain)
88 chain = self.get_chain( i, header )
90 # skip that server if the result is not consistent
96 if self.verify_chain( chain ):
97 print_error("height:", height, i.server)
99 self.save_header(header)
101 print_error("error", i.server)
102 # todo: dismiss that server
106 self.network.new_blockchain_height(height, i)
110 def calculate_target(self, bits):
116 return (a) * pow(2, 8 * (bits/MM - 3))
119 def verify_chain(self, chain):
121 first_header = chain[0]
122 prev_header = self.read_header(first_header.get('block_height') -1)
126 height = header.get('block_height')
128 prev_hash = self.hash_header(prev_header)
129 header_hash = self.hash_header(header)
132 assert prev_hash == header.get('prev_block_hash')
133 if header.get('nonce') != 0:
134 assert int('0x'+_hash,16) < self.calculate_target(header.get('bits'))
144 def verify_chunk(self, index, hexdata):
145 data = hexdata.decode('hex')
150 previous_hash = ("0"*64)
152 prev_header = self.read_header(index*2016-1)
153 if prev_header is None: raise
154 _hash = self.hash_header(prev_header)
157 height = index*2016 + i
158 raw_header = data[i*80:(i+1)*80]
159 header = self.header_from_string(raw_header)
160 header_hash = self.hash_header(header)
162 assert previous_hash == header.get('prev_block_hash')
163 if header.get('nonce') != 0:
164 assert int('0x'+header_hash,16) < calculate_target(header.get('bits'))
166 previous_header = header
167 previous_hash = header_hash
169 self.save_chunk(index, data)
170 print_error("validated chunk %d"%height)
174 def header_to_string(self, res):
175 s = int_to_hex(res.get('version'),4) \
176 + rev_hex(res.get('prev_block_hash')) \
177 + rev_hex(res.get('merkle_root')) \
178 + int_to_hex(int(res.get('timestamp')),4) \
179 + int_to_hex(int(res.get('bits')),4) \
180 + int_to_hex(int(res.get('nonce')),4)
184 def header_from_string(self, s):
185 hex_to_int = lambda s: int('0x' + s[::-1].encode('hex'), 16)
187 h['version'] = hex_to_int(s[0:4])
188 h['prev_block_hash'] = hash_encode(s[4:36])
189 h['merkle_root'] = hash_encode(s[36:68])
190 h['timestamp'] = hex_to_int(s[68:72])
191 h['bits'] = hex_to_int(s[72:76])
192 h['nonce'] = hex_to_int(s[76:80])
195 def hash_header(self, header):
196 return rev_hex(getPoWHash(self.header_to_string(header).decode('hex')).encode('hex'))
199 return os.path.join( self.config.path, 'blockchain_headers')
201 def init_headers_file(self):
202 filename = self.path()
203 if os.path.exists(filename):
207 import urllib, socket
208 socket.setdefaulttimeout(30)
209 print_error("downloading ", self.headers_url )
210 urllib.urlretrieve(self.headers_url, filename)
213 print_error( "download failed. creating file", filename )
214 open(filename,'wb+').close()
216 def save_chunk(self, index, chunk):
217 filename = self.path()
218 f = open(filename,'rb+')
219 f.seek(index*2016*80)
222 self.set_local_height()
224 def save_header(self, header):
225 data = self.header_to_string(header).decode('hex')
226 assert len(data) == 80
227 height = header.get('block_height')
228 filename = self.path()
229 f = open(filename,'rb+')
233 self.set_local_height()
236 def set_local_height(self):
238 if os.path.exists(name):
239 h = os.path.getsize(name)/80 - 1
240 if self.local_height != h:
241 self.local_height = h
244 def read_header(self, block_height):
246 if os.path.exists(name):
248 f.seek(block_height*80)
252 h = self.header_from_string(h)
255 def request_header(self, i, h, queue):
256 print_error("requesting header %d from %s"%(h, i.server))
257 i.send([ ('blockchain.block.get_header',[h])], lambda i,r: queue.put((i,r)))
259 def retrieve_header(self, i, queue):
262 ir = queue.get(timeout=1)
264 print_error('timeout')
273 print_error('Verifier received an error:', r)
281 if method == 'blockchain.block.get_header':
286 def get_chain(self, interface, final_header):
288 header = final_header
289 chain = [ final_header ]
290 requested_header = False
291 queue = Queue.Queue()
293 while self.is_running():
296 header = self.retrieve_header(interface, queue)
297 if not header: return
298 chain = [ header ] + chain
299 requested_header = False
301 height = header.get('block_height')
302 previous_header = self.read_header(height -1)
303 if not previous_header:
304 self.request_header(interface, height - 1, queue)
305 requested_header = True
308 # verify that it connects to my chain
309 prev_hash = self.hash_header(previous_header)
310 if prev_hash != header.get('prev_block_hash'):
312 self.request_header(interface, height - 1, queue)
313 requested_header = True
317 # the chain is complete
321 def get_and_verify_chunks(self, i, header, height):
323 queue = Queue.Queue()
324 min_index = (self.local_height + 1)/2016
325 max_index = (height + 1)/2016
327 while n < max_index + 1:
328 print_error( "Requesting chunk:", n )
329 r = i.synchronous_get([ ('blockchain.block.get_chunk',[n])])[0]
333 self.verify_chunk(n, r)
336 print_error('Verify chunk failed!')