simplify blockchain.py
This commit is contained in:
ThomasV
parent
81f070c83b
commit
2a1fbf01fe
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@ -21,6 +21,7 @@ import os
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import util
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from bitcoin import *
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MAX_TARGET = 0x00000000FFFF0000000000000000000000000000000000000000000000000000
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class Blockchain(util.PrintError):
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'''Manages blockchain headers and their verification'''
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@ -39,70 +40,36 @@ class Blockchain(util.PrintError):
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self.set_local_height()
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self.print_error("%d blocks" % self.local_height)
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def verify_headers(self, header, prev_header, bits, target):
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prev_hash = self.hash_header(prev_header)
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assert prev_hash == header.get('prev_block_hash'), "prev hash mismatch: %s vs %s"% (prev_hash, header.get('prev_block_hash'))
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assert bits == header.get('bits'), "bits mismatch: %s vs %s" % (bits, header.get('bits'))
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_hash = self.hash_header(header)
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assert int('0x'+_hash, 16) <= target, "insufficient proof of work: %s vs target %s" % (int('0x'+_hash, 16), target)
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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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if prev_hash != header.get('prev_block_hash'):
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self.print_error("prev hash mismatch: %s vs %s"
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% (prev_hash, header.get('prev_block_hash')))
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return False
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try:
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bits, target = self.get_target(height/2016, chain)
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except AssertionError as e:
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self.print_error("target calculation error: %s" % (str(e)))
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return False
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if bits != header.get('bits'):
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self.print_error("bits mismatch: %s vs %s"
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% (bits, header.get('bits')))
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return False
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_hash = self.hash_header(header)
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if int('0x'+_hash, 16) > target:
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self.print_error("insufficient proof of work: %s vs target %s"
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% (int('0x'+_hash, 16), target))
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return False
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bits, target = self.get_target(height/2016, chain)
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self.verify_headers(header, prev_header, bits, target)
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prev_header = header
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return True
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def verify_chunk(self, index, hexdata):
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data = hexdata.decode('hex')
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height = index*2016
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num = len(data)/80
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if index == 0:
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previous_hash = ("0"*64)
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else:
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prev_header = self.read_header(index*2016-1)
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if prev_header is None: raise
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previous_hash = self.hash_header(prev_header)
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prev_header = None if index == 0 else self.read_header(index*2016-1)
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bits, target = self.get_target(index)
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for i in range(num):
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height = index*2016 + i
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raw_header = data[i*80:(i+1)*80]
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header = self.header_from_string(raw_header)
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_hash = self.hash_header(header)
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assert previous_hash == header.get('prev_block_hash')
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assert bits == header.get('bits')
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assert int('0x'+_hash,16) <= target
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previous_header = header
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previous_hash = _hash
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header = self.deserialize_header(raw_header)
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self.verify_headers(header, prev_header, bits, target)
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prev_header = header
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self.save_chunk(index, data)
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self.print_error("validated chunk %d to height %d" % (index, height))
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self.print_error("validated chunk %d" % index)
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def header_to_string(self, res):
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def serialize_header(self, res):
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s = int_to_hex(res.get('version'),4) \
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+ rev_hex(res.get('prev_block_hash')) \
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+ rev_hex(res.get('merkle_root')) \
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@ -111,8 +78,7 @@ class Blockchain(util.PrintError):
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+ int_to_hex(int(res.get('nonce')),4)
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return s
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def header_from_string(self, s):
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def deserialize_header(self, s):
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hex_to_int = lambda s: int('0x' + s[::-1].encode('hex'), 16)
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h = {}
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h['version'] = hex_to_int(s[0:4])
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@ -124,7 +90,7 @@ class Blockchain(util.PrintError):
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return h
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def hash_header(self, header):
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return rev_hex(Hash(self.header_to_string(header).decode('hex')).encode('hex'))
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return "0"*64 if header is None else rev_hex(Hash(self.serialize_header(header).decode('hex')).encode('hex'))
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def path(self):
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return os.path.join(self.config.path, 'blockchain_headers')
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@ -152,7 +118,7 @@ class Blockchain(util.PrintError):
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self.set_local_height()
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def save_header(self, header):
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data = self.header_to_string(header).decode('hex')
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data = self.serialize_header(header).decode('hex')
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assert len(data) == 80
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height = header.get('block_height')
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filename = self.path()
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@ -177,23 +143,19 @@ class Blockchain(util.PrintError):
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h = f.read(80)
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f.close()
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if len(h) == 80:
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h = self.header_from_string(h)
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h = self.deserialize_header(h)
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return h
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def get_target(self, index, chain=None):
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if chain is None:
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chain = [] # Do not use mutables as default values!
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max_target = 0x00000000FFFF0000000000000000000000000000000000000000000000000000
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if index == 0: return 0x1d00ffff, max_target
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if index == 0:
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return 0x1d00ffff, MAX_TARGET
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first = self.read_header((index-1)*2016)
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last = self.read_header(index*2016-1)
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if last is None:
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for h in chain:
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if h.get('block_height') == index*2016-1:
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last = h
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assert last is not None
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# bits to target
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bits = last.get('bits')
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bitsN = (bits >> 24) & 0xff
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@ -201,24 +163,20 @@ class Blockchain(util.PrintError):
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bitsBase = bits & 0xffffff
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assert bitsBase >= 0x8000 and bitsBase <= 0x7fffff, "Second part of bits should be in [0x8000, 0x7fffff]"
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target = bitsBase << (8*(bitsN-3))
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# new target
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nActualTimespan = last.get('timestamp') - first.get('timestamp')
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nTargetTimespan = 14*24*60*60
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nActualTimespan = max(nActualTimespan, nTargetTimespan/4)
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nActualTimespan = min(nActualTimespan, nTargetTimespan*4)
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new_target = min(max_target, (target * nActualTimespan)/nTargetTimespan)
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new_target = min(MAX_TARGET, (target * nActualTimespan)/nTargetTimespan)
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# convert new target to bits
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c = ("%064x" % new_target)[2:]
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while c[:2] == '00' and len(c) > 6:
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c = c[2:]
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bitsN, bitsBase = len(c)/2, int('0x'+c[:6], 16)
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if bitsBase >= 0x800000:
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bitsN += 1
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bitsBase >>= 8
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new_bits = bitsN << 24 | bitsBase
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return new_bits, bitsBase << (8*(bitsN-3))
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@ -242,18 +200,20 @@ class Blockchain(util.PrintError):
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# The chain is complete. Reverse to order by increasing height
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chain.reverse()
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if self.verify_chain(chain):
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try:
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self.verify_chain(chain)
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self.print_error("connected at height:", previous_height)
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for header in chain:
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self.save_header(header)
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return True
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return False
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except BaseException as e:
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self.print_error(str(e))
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return False
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def connect_chunk(self, idx, chunk):
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try:
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self.verify_chunk(idx, chunk)
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return idx + 1
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except Exception:
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self.print_error('verify_chunk failed')
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except BaseException as e:
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self.print_error('verify_chunk failed', str(e))
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return idx - 1
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