def decode_transaction(stream: io.BytesIO) -> (bool, Transaction): # ensure the at the magic is correctly configured magic = stream.read(1)[0] if magic != MAGIC: raise RuntimeError('Unable to parse transaction from stream, invalid magic') # extract the header bytes header = stream.read(2) # parse the header types version = (header[0] & 0xE0) >> 5 charge_unit_flag = bool((header[0] & 0x08) >> 3) transfer_flag = bool((header[0] & 0x04) >> 2) multiple_transfers_flag = bool((header[0] & 0x02) >> 1) valid_from_flag = bool((header[0] & 0x01)) contract_type = (header[1] & 0xC0) >> 6 signature_count_minus1 = (header[1] & 0x3F) num_signatures = signature_count_minus1 + 1 # ensure that the version is correct if version != VERSION: raise RuntimeError('Unable to parse transaction from stream, incompatible version') # Ready empty reserved byte stream.read(1) tx = Transaction() # decode the address from the thread tx.from_address = address.decode(stream) if transfer_flag: # determine the number of transfers that are present in the transaction if multiple_transfers_flag: transfer_count = integer.decode(stream) + 2 else: transfer_count = 1 for n in range(transfer_count): to = address.decode(stream) amount = integer.decode(stream) tx.add_transfer(to, amount) if valid_from_flag: tx.valid_from = integer.decode(stream) tx.valid_until = integer.decode(stream) tx.charge_rate = integer.decode(stream) assert not charge_unit_flag, "Currently the charge unit field is not supported" tx.charge_limit = integer.decode(stream) if contract_type != NO_CONTRACT: contract_header = int(stream.read(1)[0]) wildcard = bool(contract_header & 0x80) shard_mask = BitVector() if not wildcard: extended_shard_mask_flag = bool(contract_header & 0x40) if not extended_shard_mask_flag: if contract_header & 0x10: mask = 0xf bit_size = 4 else: mask = 0x3 bit_size = 2 # extract the shard mask from the header shard_mask = BitVector.from_bytes(bytes([contract_header & mask]), bit_size) else: bit_length = 1 << ((contract_header & 0x3F) + 3) byte_length = bit_length // 8 assert (bit_length % 8) == 0 # this should be enforced as part of the spec # extract the mask from the next N bytes shard_mask = BitVector.from_bytes(stream.read(byte_length), bit_length) if contract_type == SMART_CONTRACT or contract_type == SYNERGETIC: contract_digest = address.decode(stream) contract_address = address.decode(stream) tx.target_contract(contract_digest, contract_address, shard_mask) elif contract_type == CHAIN_CODE: encoded_chain_code_name = bytearray.decode(stream) tx.target_chain_code(encoded_chain_code_name.decode('ascii'), shard_mask) else: # this is mostly a guard against a desync between this function and `_map_contract_mode` raise RuntimeError("Unhandled contract type") tx.action = bytearray.decode(stream).decode('ascii') tx.data = bytearray.decode(stream) # Read counter value tx.counter = struct.unpack('<Q', stream.read(8))[0] if signature_count_minus1 == 0x3F: additional_signatures = integer.decode(stream) num_signatures += additional_signatures # extract all the signing public keys from the stream public_keys = [identity.decode(stream) for _ in range(num_signatures)] # extract full copy of the payload payload_bytes = stream.getvalue()[:stream.tell()] verified = [] for ident in public_keys: # for n in range(num_signatures): # extract the signature from the stream signature = bytearray.decode(stream) # verify if this signature is correct verified.append(ident.verify(payload_bytes, signature)) # build a metadata object to store in the tx tx._signers[ident] = { 'signature': signature, 'verified': verified[-1], } return all(verified), tx
def test_binary(self): bits = BitVector.from_bytes(bytes([0x1f]), 8) self.assertEqual('00011111', bits.as_binary())