tselect the longest blockchain from several servers - electrum - Electrum Bitcoin wallet
HTML git clone https://git.parazyd.org/electrum
DIR Log
DIR Files
DIR Refs
DIR Submodules
---
DIR commit 2a6e8927ddc3e60cf18e01da395031efae032de7
DIR parent 48efc62b2d5c30d296ea228bc91b62afbade8f90
HTML Author: thomasv <thomasv@gitorious>
Date: Mon, 2 Sep 2013 17:49:12 +0200
select the longest blockchain from several servers
Diffstat:
M lib/blockchain.py | 243 +++++++++++++++++++++----------
M lib/interface.py | 3 ++-
M lib/verifier.py | 12 +++++++++++-
3 files changed, 176 insertions(+), 82 deletions(-)
---
DIR diff --git a/lib/blockchain.py b/lib/blockchain.py
t@@ -29,79 +29,71 @@ class BlockchainVerifier(threading.Thread):
threading.Thread.__init__(self)
self.daemon = True
self.config = config
- self.interface = interface
- self.interface.register_channel('verifier')
self.lock = threading.Lock()
- self.pending_headers = [] # headers that have not been verified
self.height = 0
self.local_height = 0
self.running = False
self.headers_url = 'http://headers.electrum.org/blockchain_headers'
+ self.interface = interface
+ interface.register_channel('verifier')
+ self.set_local_height()
+
+
+
+ def start_interfaces(self):
+ import interface
+ servers = interface.DEFAULT_SERVERS
+ servers = interface.filter_protocol(servers,'s')
+ print_error("using %d servers"% len(servers))
+ self.interfaces = map ( lambda server: interface.Interface({'server':server} ), servers )
+
+ for i in self.interfaces:
+ i.start()
+ # subscribe to block headers
+ i.register_channel('verifier')
+ i.register_channel('get_header')
+ i.send([ ('blockchain.headers.subscribe',[])], 'verifier')
+ # note: each interface should send its results directly to a queue, instead of channels
+ # pass the queue to the interface, so that several can share the same queue
+
+
+ def get_new_response(self):
+ # listen to interfaces, forward to verifier using the queue
+ while 1:
+ for i in self.interfaces:
+ try:
+ r = i.get_response('verifier',timeout=0)
+ except Queue.Empty:
+ continue
+
+ result = r.get('result')
+ if result:
+ return (i,result)
+
+ time.sleep(1)
+
+
def stop(self):
with self.lock: self.running = False
- self.interface.poke('verifier')
+ #self.interface.poke('verifier')
def is_running(self):
with self.lock: return self.running
- def run(self):
- self.init_headers_file()
- self.set_local_height()
-
- with self.lock:
- self.running = True
- requested_chunks = []
- requested_headers = []
- all_chunks = False
-
- # subscribe to block headers
- self.interface.send([ ('blockchain.headers.subscribe',[])], 'verifier')
-
- while self.is_running():
- # request missing chunks
- if not all_chunks and self.height and not requested_chunks:
-
- if self.local_height + 50 < self.height:
- min_index = (self.local_height + 1)/2016
- max_index = (self.height + 1)/2016
- for i in range(min_index, max_index + 1):
- print_error( "requesting chunk", i )
- self.interface.send([ ('blockchain.block.get_chunk',[i])], 'verifier')
- requested_chunks.append(i)
- break
- else:
- all_chunks = True
- print_error("downloaded all chunks")
-
-
- # process pending headers
- if self.pending_headers and all_chunks:
- done = []
- for header in self.pending_headers:
- if self.verify_header(header):
- done.append(header)
- else:
- # request previous header
- i = header.get('block_height') - 1
- if i not in requested_headers:
- print_error("requesting header %d"%i)
- self.interface.send([ ('blockchain.block.get_header',[i])], 'verifier')
- requested_headers.append(i)
- # no point continuing
- break
- if done:
- self.interface.trigger_callback('updated')
- for header in done:
- self.pending_headers.remove(header)
+ def request_header(self, i, h):
+ print_error("requesting header %d from %s"%(h, i.server))
+ i.send([ ('blockchain.block.get_header',[h])], 'get_header')
+ def retrieve_header(self, i):
+ while True:
try:
- r = self.interface.get_response('verifier',timeout=1)
+ r = i.get_response('get_header',timeout=1)
except Queue.Empty:
+ print_error('timeout')
continue
- if not r: continue
if r.get('error'):
print_error('Verifier received an error:', r)
t@@ -112,23 +104,66 @@ class BlockchainVerifier(threading.Thread):
params = r['params']
result = r['result']
- if method == 'blockchain.block.get_chunk':
- index = params[0]
- self.verify_chunk(index, result)
- requested_chunks.remove(index)
+ if method == 'blockchain.block.get_header':
+ return result
+
- elif method in ['blockchain.headers.subscribe', 'blockchain.block.get_header']:
+ def get_chain(self, interface, final_header):
- self.pending_headers.append(result)
- if method == 'blockchain.block.get_header':
- requested_headers.remove(result.get('block_height'))
- else:
- self.height = result.get('block_height')
- ## fixme # self.interface.poke('synchronizer')
-
- self.pending_headers.sort(key=lambda x: x.get('block_height'))
- # print "pending headers", map(lambda x: x.get('block_height'), self.pending_headers)
+ header = final_header
+ chain = [ final_header ]
+ requested_header = False
+
+ while self.is_running():
+
+ if requested_header:
+ header = self.retrieve_header(interface)
+ if not header: return
+ chain = [ header ] + chain
+ requested_header = False
+
+ height = header.get('block_height')
+ previous_header = self.read_header(height -1)
+ if not previous_header:
+ self.request_header(interface, height - 1)
+ requested_header = True
+ continue
+
+ # verify that it connects to my chain
+ prev_hash = self.hash_header(previous_header)
+ if prev_hash != header.get('prev_block_hash'):
+ print_error("reorg")
+ self.request_header(interface, height - 1)
+ requested_header = True
+ continue
+
+ else:
+ # the chain is complete
+ return chain
+
+
+ def verify_chain(self, chain):
+
+ first_header = chain[0]
+ prev_header = self.read_header(first_header.get('block_height') -1)
+
+ for header in chain:
+ height = header.get('block_height')
+
+ prev_hash = self.hash_header(prev_header)
+ bits, target = self.get_target(height/2016)
+ _hash = self.hash_header(header)
+ try:
+ assert prev_hash == header.get('prev_block_hash')
+ assert bits == header.get('bits')
+ assert eval('0x'+_hash) < target
+ except:
+ return False
+
+ prev_header = header
+
+ return True
t@@ -184,17 +219,8 @@ class BlockchainVerifier(threading.Thread):
except:
# this can be caused by a reorg.
print_error("verify header failed"+ repr(header))
- # undo verifications
- with self.lock:
- items = self.verified_tx.items()[:]
- for tx_hash, item in items:
- tx_height, timestamp, pos = item
- if tx_height >= height:
- print_error("redoing", tx_hash)
- with self.lock:
- self.verified_tx.pop(tx_hash)
- if tx_hash in self.merkle_roots:
- self.merkle_roots.pop(tx_hash)
+ verifier.undo_verifications()
+
# return False to request previous header.
return False
t@@ -272,6 +298,7 @@ class BlockchainVerifier(threading.Thread):
h = os.path.getsize(name)/80 - 1
if self.local_height != h:
self.local_height = h
+ self.height = self.local_height
def read_header(self, block_height):
t@@ -327,3 +354,59 @@ class BlockchainVerifier(threading.Thread):
+
+ def run(self):
+ self.start_interfaces()
+
+ self.init_headers_file()
+ self.set_local_height()
+ print_error( "blocks:", self.local_height )
+
+ with self.lock:
+ self.running = True
+
+ while self.is_running():
+
+ i, header = self.get_new_response()
+
+ height = header.get('block_height')
+
+ if height > self.local_height:
+ # get missing parts from interface (until it connects to my chain)
+ chain = self.get_chain( i, header )
+
+ # skip that server if the result is not consistent
+ if not chain: continue
+
+ # verify the chain
+ if self.verify_chain( chain ):
+ print_error("height:", height, i.server)
+ for header in chain:
+ self.save_header(header)
+ self.height = height
+ else:
+ print_error("error", i.server)
+ # todo: dismiss that server
+
+
+
+
+
+if __name__ == "__main__":
+ import interface, simple_config
+
+ config = simple_config.SimpleConfig({'verbose':True})
+
+ i0 = interface.Interface()
+ i0.start()
+
+ bv = BlockchainVerifier(i0, config)
+ bv.start()
+
+
+ # listen to interfaces, forward to verifier using the queue
+ while 1:
+ time.sleep(1)
+
+
+
DIR diff --git a/lib/interface.py b/lib/interface.py
t@@ -332,7 +332,8 @@ class Interface(threading.Thread):
try:
s.connect(( self.host.encode('ascii'), int(self.port)))
except:
- traceback.print_exc(file=sys.stdout)
+ #traceback.print_exc(file=sys.stdout)
+ print_error("failed to connect", host, port)
self.is_connected = False
self.s = None
return
DIR diff --git a/lib/verifier.py b/lib/verifier.py
t@@ -155,4 +155,14 @@ class TxVerifier(threading.Thread):
-
+ def undo_verifications(self, height):
+ with self.lock:
+ items = self.verified_tx.items()[:]
+ for tx_hash, item in items:
+ tx_height, timestamp, pos = item
+ if tx_height >= height:
+ print_error("redoing", tx_hash)
+ with self.lock:
+ self.verified_tx.pop(tx_hash)
+ if tx_hash in self.merkle_roots:
+ self.merkle_roots.pop(tx_hash)