def validate_transaction(self, transaction):
"""Validate a transaction.
Args:
transaction (dict): transaction to validate.
Returns:
The transaction if the transaction is valid else it raises and exception
describing the reason why the transaction is invalid.
Raises:
OperationError: if the transaction operation is not supported
TransactionDoesNotExist: if the input of the transaction is not found
TransactionOwnerError: if the new transaction is using an input it doesn't own
DoubleSpend: if the transaction is a double spend
InvalidHash: if the hash of the transaction is wrong
InvalidSignature: if the signature of the transaction is wrong
"""
# If the operation is CREATE the transaction should have no inputs and should be signed by a
# federation node
if transaction['transaction']['operation'] == 'CREATE':
if transaction['transaction']['input']:
raise ValueError('A CREATE operation has no inputs')
if not (set(transaction['transaction']['current_owners']) <=
set(self.federation_nodes + [self.me])):
raise exceptions.OperationError(
'Only federation nodes can use the operation `CREATE`')
else:
# check if the input exists, is owned by the current_owner
if not transaction['transaction']['input']:
raise ValueError(
'Only `CREATE` transactions can have null inputs')
tx_input = self.get_transaction(
transaction['transaction']['input'])
if not tx_input:
raise exceptions.TransactionDoesNotExist(
'input `{}` does not exist in the bigchain'.format(
transaction['transaction']['input']))
if tx_input['transaction']['new_owners'] != transaction[
'transaction']['current_owners']:
raise exceptions.TransactionOwnerError(
'current_owner `{}` does not own the input `{}`'.format(
transaction['transaction']['current_owners'],
transaction['transaction']['input']))
# check if the input was already spent by a transaction other then this one.
spent = self.get_spent(tx_input['id'])
if spent:
if spent['id'] != transaction['id']:
raise exceptions.DoubleSpend(
'input `{}` was already spent'.format(
transaction['transaction']['input']))
util.check_hash_and_signature(transaction)
return transaction
def validate_transaction(bigchain, transaction):
"""Validate a transaction.
Args:
bigchain (Bigchain): an instantiated bigchaindb.Bigchain object.
transaction (dict): transaction to validate.
Returns:
The transaction if the transaction is valid else it raises an
exception describing the reason why the transaction is invalid.
Raises:
OperationError: if the transaction operation is not supported
TransactionDoesNotExist: if the input of the transaction is not found
TransactionOwnerError: if the new transaction is using an input it doesn't own
DoubleSpend: if the transaction is a double spend
InvalidHash: if the hash of the transaction is wrong
InvalidSignature: if the signature of the transaction is wrong
"""
# If the operation is CREATE the transaction should have no inputs and
# should be signed by a federation node
if transaction['transaction']['operation'] == 'CREATE':
if transaction['transaction']['input']:
raise ValueError('A CREATE operation has no inputs')
if transaction['transaction']['current_owner'] not in (
bigchain.federation_nodes + [bigchain.me]):
raise exceptions.OperationError(
'Only federation nodes can use the operation `CREATE`')
else:
# check if the input exists, is owned by the current_owner
if not transaction['transaction']['input']:
raise ValueError(
'Only `CREATE` transactions can have null inputs')
tx_input = bigchain.get_transaction(
transaction['transaction']['input'])
if not tx_input:
raise exceptions.TransactionDoesNotExist(
'input `{}` does not exist in the bigchain'.format(
transaction['transaction']['input']))
if (tx_input['transaction']['new_owner'] !=
transaction['transaction']['current_owner']):
raise exceptions.TransactionOwnerError(
'current_owner `{}` does not own the input `{}`'.format(
transaction['transaction']['current_owner'],
transaction['transaction']['input']))
# check if the input was already spent by a transaction other than
# this one.
spent = bigchain.get_spent(tx_input['id'])
if spent and spent['id'] != transaction['id']:
raise exceptions.DoubleSpend(
'input `{}` was already spent'.format(
transaction['transaction']['input']))
# Check hash of the transaction
calculated_hash = crypto.hash_data(
util.serialize(transaction['transaction']))
if calculated_hash != transaction['id']:
raise exceptions.InvalidHash()
# Check signature
if not util.verify_signature(transaction):
raise exceptions.InvalidSignature()
return transaction