select the longest blockchain from several servers
This commit is contained in:
thomasv
parent
48efc62b2d
commit
2a6e8927dd
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@ -29,79 +29,71 @@ class BlockchainVerifier(threading.Thread):
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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.interface.register_channel('verifier')
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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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self.interface = interface
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interface.register_channel('verifier')
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self.set_local_height()
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def start_interfaces(self):
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import interface
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servers = interface.DEFAULT_SERVERS
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servers = interface.filter_protocol(servers,'s')
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print_error("using %d servers"% len(servers))
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self.interfaces = map ( lambda server: interface.Interface({'server':server} ), servers )
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for i in self.interfaces:
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i.start()
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# subscribe to block headers
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i.register_channel('verifier')
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i.register_channel('get_header')
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i.send([ ('blockchain.headers.subscribe',[])], 'verifier')
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# note: each interface should send its results directly to a queue, instead of channels
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# pass the queue to the interface, so that several can share the same queue
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def get_new_response(self):
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# listen to interfaces, forward to verifier using the queue
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while 1:
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for i in self.interfaces:
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try:
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r = i.get_response('verifier',timeout=0)
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except Queue.Empty:
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continue
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result = r.get('result')
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if result:
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return (i,result)
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time.sleep(1)
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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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#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_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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# 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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def request_header(self, i, h):
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print_error("requesting header %d from %s"%(h, i.server))
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i.send([ ('blockchain.block.get_header',[h])], 'get_header')
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def retrieve_header(self, i):
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while True:
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try:
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r = self.interface.get_response('verifier',timeout=1)
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r = i.get_response('get_header',timeout=1)
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except Queue.Empty:
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print_error('timeout')
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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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@ -112,23 +104,66 @@ class BlockchainVerifier(threading.Thread):
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params = r['params']
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result = r['result']
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if 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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## fixme # self.interface.poke('synchronizer')
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if method == 'blockchain.block.get_header':
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return result
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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 get_chain(self, interface, final_header):
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header = final_header
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chain = [ final_header ]
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requested_header = False
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while self.is_running():
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if requested_header:
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header = self.retrieve_header(interface)
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if not header: return
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chain = [ header ] + chain
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requested_header = False
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height = header.get('block_height')
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previous_header = self.read_header(height -1)
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if not previous_header:
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self.request_header(interface, height - 1)
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requested_header = True
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continue
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# verify that it connects to my chain
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prev_hash = self.hash_header(previous_header)
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if prev_hash != header.get('prev_block_hash'):
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print_error("reorg")
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self.request_header(interface, height - 1)
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requested_header = True
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continue
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else:
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# the chain is complete
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return chain
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def verify_chain(self, chain):
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first_header = chain[0]
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prev_header = self.read_header(first_header.get('block_height') -1)
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for header in chain:
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height = header.get('block_height')
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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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return False
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prev_header = header
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return True
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@ -184,17 +219,8 @@ class BlockchainVerifier(threading.Thread):
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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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verifier.undo_verifications()
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# return False to request previous header.
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return False
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@ -272,6 +298,7 @@ class BlockchainVerifier(threading.Thread):
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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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self.height = self.local_height
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def read_header(self, block_height):
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@ -327,3 +354,59 @@ class BlockchainVerifier(threading.Thread):
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def run(self):
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self.start_interfaces()
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self.init_headers_file()
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self.set_local_height()
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print_error( "blocks:", self.local_height )
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with self.lock:
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self.running = True
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while self.is_running():
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i, header = self.get_new_response()
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height = header.get('block_height')
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if height > self.local_height:
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# get missing parts from interface (until it connects to my chain)
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chain = self.get_chain( i, header )
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# skip that server if the result is not consistent
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if not chain: continue
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# verify the chain
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if self.verify_chain( chain ):
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print_error("height:", height, i.server)
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for header in chain:
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self.save_header(header)
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self.height = height
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else:
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print_error("error", i.server)
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# todo: dismiss that server
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if __name__ == "__main__":
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import interface, simple_config
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config = simple_config.SimpleConfig({'verbose':True})
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i0 = interface.Interface()
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i0.start()
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bv = BlockchainVerifier(i0, config)
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bv.start()
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# listen to interfaces, forward to verifier using the queue
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while 1:
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time.sleep(1)
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@ -332,7 +332,8 @@ class Interface(threading.Thread):
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try:
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s.connect(( self.host.encode('ascii'), int(self.port)))
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except:
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traceback.print_exc(file=sys.stdout)
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#traceback.print_exc(file=sys.stdout)
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print_error("failed to connect", host, port)
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self.is_connected = False
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self.s = None
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return
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@ -155,4 +155,14 @@ class TxVerifier(threading.Thread):
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def undo_verifications(self, height):
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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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