def get_balance(address):
blockchain = Blockchain()
return json.dumps(blockchain.get_balance(address))
class Validator(object):
def __init__(self):
self.blockchain = Blockchain()
self.mempool = Mempool()
def check_hash_and_hash_pattern(self, block):
hash_difficulty = self.blockchain.calculate_hash_difficulty(
block.height)
if block.block_header.hash[:hash_difficulty].count(
'0') != hash_difficulty:
raise InvalidHash(
block.height,
"Incompatible Block Hash: {}".format(block.block_header.hash))
return
def check_height_and_previous_hash(self, block):
previous_block = self.blockchain.get_block_header_by_hash(
block.block_header.previous_hash)
if previous_block is None:
raise ChainContinuityError(
block.height,
"Incompatible block hash: {} and hash: {}".format(
block.height - 1, block.block_header.previous_hash))
previous_block_header, previous_block_branch, previous_block_height = previous_block
if previous_block_height != block.height - 1:
raise ChainContinuityError(
block.height,
"Incompatible block height: {}".format(block.height - 1))
return
def check_block_reward(self, block):
reward_amount = self.blockchain.get_reward(block.height)
for transaction in block.transactions[1:]:
if TransactionType(
transaction.tx_type) == TransactionType.COINBASE:
logger.warning("Block not valid. Multiple coinbases detected")
return False
reward_amount += transaction.fee
# first transaction is coinbase
reward_transaction = block.transactions[0]
if TransactionType(
reward_transaction.tx_type) != TransactionType.COINBASE:
logger.warning("Block not valid. Missing coinbase")
return False
if reward_transaction.amount != reward_amount:
logger.warning("Invalid block reward {} should be {}".format(
reward_transaction.amount, reward_amount))
return False
if reward_transaction.source != "0":
logger.warning("Invalid Coinbase source")
return False
return True
def validate_block_header(self, block_header, transactions_inv):
if self.blockchain.get_block_header_by_hash(block_header.hash):
logger.warning('Block Header already exists')
return False
if block_header.version != config['network']['version']:
logger.warning('Incompatible version')
return False
if block_header.merkle_root != self.calculate_merkle_root(
transactions_inv):
logger.warning('Invalid merkle root')
return False
previous_block = self.blockchain.get_block_header_by_hash(
block_header.previous_hash)
if previous_block is None:
return None
previous_block_header, previous_block_branch, previous_block_height = previous_block
if self.blockchain.calculate_hash_difficulty(
previous_block_height + 1) > block_header.hash_difficulty:
logger.warning('Invalid hash difficulty')
return False
return previous_block_height + 1
def validate_block(self, block, merkle_root):
if block.block_header.merkle_root != merkle_root:
logger.warning("invalid merkle root")
return False
if not self.check_block_reward(block):
logger.warning("Invalid block reward")
return False
return True
def validate_block_transactions_inv(self, transactions_inv):
"""
Checks a list of transaction hashes, checks for double-spends and/or entries in the mempool
Returns a list of unknown transaction hashes
:param transactions_inv:
:return: block_transactions, missing_transactions_inv
:rtype: tuple(list, list)
"""
missing_transactions_inv = []
block_transactions = []
for tx_hash in transactions_inv:
if self.blockchain.find_duplicate_transactions(tx_hash):
logger.warning(
'Transaction not valid. Double-spend prevented: {}'.
format(tx_hash))
return False
transaction = self.mempool.get_unconfirmed_transaction(tx_hash)
if transaction is None:
missing_transactions_inv.append(tx_hash)
else:
block_transactions.append(transaction)
return block_transactions, missing_transactions_inv
def validate_transaction(self, transaction):
"""
Validate a single transaction. Check for double-spend, invalid signature, and insufficient funds
:param transaction:
:return: boolean
:rtype: boolean
"""
if self.blockchain.find_duplicate_transactions(transaction.tx_hash):
logger.warning(
'Transaction not valid. Double-spend prevented: {}'.format(
transaction.tx_hash))
return False
if not transaction.verify():
logger.warning(
'Transaction not valid. Invalid transaction signature: {}'.
format(transaction.tx_hash))
return False
balance = self.blockchain.get_balance(transaction.source)
if transaction.amount + transaction.fee > balance:
logger.warning(
'Transaction not valid. Insufficient funds: {} {}<{}'.format(
transaction.tx_hash, balance,
transaction.amount + transaction.fee))
return False
return True
@staticmethod
def calculate_merkle_root(tx_hashes):
coinbase_hash = tx_hashes[0]
merkle_base = sorted(tx_hashes[1:])
merkle_base.insert(0, coinbase_hash)
while len(merkle_base) > 1:
temp_merkle_base = []
for i in range(0, len(merkle_base), 2):
if i == len(merkle_base) - 1:
temp_merkle_base.append(
hashlib.sha256(merkle_base[i]).hexdigest())
else:
temp_merkle_base.append(
hashlib.sha256(merkle_base[i] +
merkle_base[i + 1]).hexdigest())
merkle_base = temp_merkle_base
return merkle_base[0]