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electrum
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Small blockchain changes

283
Kirill Fomichev 9 years ago
parent
06eb3142c4
commit
d344ee0474
1 changed files with 41 additions and 37 deletions
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  1. 78
      lib/blockchain.py

78
lib/blockchain.py
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@ -28,7 +28,7 @@ class Blockchain(util.PrintError):
def __init__(self, config, network):
self.config = config
self.network = network
self.headers_url = 'https://headers.electrum.org/blockchain_headers'
self.headers_url = "https://headers.electrum.org/blockchain_headers"
self.local_height = 0
self.set_local_height()
@ -40,42 +40,42 @@ class Blockchain(util.PrintError):
self.set_local_height()
self.print_error("%d blocks" % self.local_height)
def verify_headers(self, header, prev_header, bits, target):
def verify_header(self, header, prev_header, bits, target):
prev_hash = self.hash_header(prev_header)
assert prev_hash == header.get('prev_block_hash'), "prev hash mismatch: %s vs %s"% (prev_hash, header.get('prev_block_hash'))
assert prev_hash == header.get('prev_block_hash'), "prev hash mismatch: %s vs %s" % (prev_hash, header.get('prev_block_hash'))
assert bits == header.get('bits'), "bits mismatch: %s vs %s" % (bits, header.get('bits'))
_hash = self.hash_header(header)
assert int('0x'+_hash, 16) <= target, "insufficient proof of work: %s vs target %s" % (int('0x'+_hash, 16), target)
assert int('0x' + _hash, 16) <= target, "insufficient proof of work: %s vs target %s" % (int('0x' + _hash, 16), target)
def verify_chain(self, chain):
first_header = chain[0]
prev_header = self.read_header(first_header.get('block_height') -1)
prev_header = self.read_header(first_header.get('block_height') - 1)
for header in chain:
height = header.get('block_height')
bits, target = self.get_target(height/2016, chain)
self.verify_headers(header, prev_header, bits, target)
bits, target = self.get_target(height / 2016, chain)
self.verify_header(header, prev_header, bits, target)
prev_header = header
def verify_chunk(self, index, hexdata):
data = hexdata.decode('hex')
num = len(data)/80
prev_header = None if index == 0 else self.read_header(index*2016-1)
num = len(data) / 80
prev_header = None
if index != 0:
prev_header = self.read_header(index*2016 - 1)
bits, target = self.get_target(index)
for i in range(num):
raw_header = data[i*80:(i+1)*80]
raw_header = data[i*80:(i+1) * 80]
header = self.deserialize_header(raw_header)
self.verify_headers(header, prev_header, bits, target)
self.verify_header(header, prev_header, bits, target)
prev_header = header
self.save_chunk(index, data)
self.print_error("validated chunk %d" % index)
def serialize_header(self, res):
s = int_to_hex(res.get('version'),4) \
s = int_to_hex(res.get('version'), 4) \
+ rev_hex(res.get('prev_block_hash')) \
+ rev_hex(res.get('merkle_root')) \
+ int_to_hex(int(res.get('timestamp')),4) \
+ int_to_hex(int(res.get('bits')),4) \
+ int_to_hex(int(res.get('nonce')),4)
+ int_to_hex(int(res.get('timestamp')), 4) \
+ int_to_hex(int(res.get('bits')), 4) \
+ int_to_hex(int(res.get('nonce')), 4)
return s
def deserialize_header(self, s):
@ -90,7 +90,9 @@ class Blockchain(util.PrintError):
return h
def hash_header(self, header):
return "0"*64 if header is None else rev_hex(Hash(self.serialize_header(header).decode('hex')).encode('hex'))
if header is None:
return '0' * 64
return hash_encode(Hash(self.serialize_header(header).decode('hex')))
def path(self):
return os.path.join(self.config.path, 'blockchain_headers')
@ -102,17 +104,17 @@ class Blockchain(util.PrintError):
try:
import urllib, socket
socket.setdefaulttimeout(30)
self.print_error("downloading ", self.headers_url )
self.print_error("downloading ", self.headers_url)
urllib.urlretrieve(self.headers_url, filename)
self.print_error("done.")
except Exception:
self.print_error( "download failed. creating file", filename )
open(filename,'wb+').close()
self.print_error("download failed. creating file", filename)
open(filename, 'wb+').close()
def save_chunk(self, index, chunk):
filename = self.path()
f = open(filename,'rb+')
f.seek(index*2016*80)
f = open(filename, 'rb+')
f.seek(index * 2016 * 80)
h = f.write(chunk)
f.close()
self.set_local_height()
@ -122,8 +124,8 @@ class Blockchain(util.PrintError):
assert len(data) == 80
height = header.get('block_height')
filename = self.path()
f = open(filename,'rb+')
f.seek(height*80)
f = open(filename, 'rb+')
f.seek(height * 80)
h = f.write(data)
f.close()
self.set_local_height()
@ -138,8 +140,8 @@ class Blockchain(util.PrintError):
def read_header(self, block_height):
name = self.path()
if os.path.exists(name):
f = open(name,'rb')
f.seek(block_height*80)
f = open(name, 'rb')
f.seek(block_height * 80)
h = f.read(80)
f.close()
if len(h) == 80:
@ -149,11 +151,11 @@ class Blockchain(util.PrintError):
def get_target(self, index, chain=None):
if index == 0:
return 0x1d00ffff, MAX_TARGET
first = self.read_header((index-1)*2016)
last = self.read_header(index*2016-1)
first = self.read_header((index-1) * 2016)
last = self.read_header(index*2016 - 1)
if last is None:
for h in chain:
if h.get('block_height') == index*2016-1:
if h.get('block_height') == index*2016 - 1:
last = h
assert last is not None
# bits to target
@ -162,23 +164,23 @@ class Blockchain(util.PrintError):
assert bitsN >= 0x03 and bitsN <= 0x1d, "First part of bits should be in [0x03, 0x1d]"
bitsBase = bits & 0xffffff
assert bitsBase >= 0x8000 and bitsBase <= 0x7fffff, "Second part of bits should be in [0x8000, 0x7fffff]"
target = bitsBase << (8*(bitsN-3))
target = bitsBase << (8 * (bitsN-3))
# new target
nActualTimespan = last.get('timestamp') - first.get('timestamp')
nTargetTimespan = 14*24*60*60
nActualTimespan = max(nActualTimespan, nTargetTimespan/4)
nActualTimespan = min(nActualTimespan, nTargetTimespan*4)
new_target = min(MAX_TARGET, (target * nActualTimespan)/nTargetTimespan)
nTargetTimespan = 14 * 24 * 60 * 60
nActualTimespan = max(nActualTimespan, nTargetTimespan / 4)
nActualTimespan = min(nActualTimespan, nTargetTimespan * 4)
new_target = min(MAX_TARGET, (target*nActualTimespan) / nTargetTimespan)
# convert new target to bits
c = ("%064x" % new_target)[2:]
while c[:2] == '00' and len(c) > 6:
c = c[2:]
bitsN, bitsBase = len(c)/2, int('0x'+c[:6], 16)
bitsN, bitsBase = len(c) / 2, int('0x' + c[:6], 16)
if bitsBase >= 0x800000:
bitsN += 1
bitsBase >>= 8
new_bits = bitsN << 24 | bitsBase
return new_bits, bitsBase << (8*(bitsN-3))
return new_bits, bitsBase << (8 * (bitsN-3))
def connect_header(self, chain, header):
'''Builds a header chain until it connects. Returns True if it has
@ -213,6 +215,8 @@ class Blockchain(util.PrintError):
def connect_chunk(self, idx, chunk):
try:
self.verify_chunk(idx, chunk)
self.print_error("validated chunk %d" % index)
self.save_chunk(index, data)
return idx + 1
except BaseException as e:
self.print_error('verify_chunk failed', str(e))

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