def get_funds_fields_from_struct(self, buf: bytes) -> bytes:
""" Gets all funds fields for a transaction from a buffer.
:param buf: Bytes of a serialized transaction
:type buf: bytes
:return: A buffer containing the remaining struct bytes
:rtype: bytes
:raises ValueError: when the sequence of bytes is incorect
"""
(self.version, inputs_len, outputs_len), buf = unpack(_FUNDS_FORMAT_STRING, buf)
for _ in range(inputs_len):
txin, buf = TxInput.create_from_bytes(buf)
self.inputs.append(txin)
for _ in range(outputs_len):
txout, buf = TxOutput.create_from_bytes(buf)
self.outputs.append(txout)
# token name and symbol
self.token_name, self.token_symbol, buf = TokenCreationTransaction.deserialize_token_info(buf)
return buf
def deserialize_token_info(cls, buf: bytes) -> Tuple[str, str, bytes]:
""" Gets the token name and symbol from serialized format
"""
(token_info_version,), buf = unpack('!B', buf)
if token_info_version != TOKEN_INFO_VERSION:
raise ValueError('unknown token info version: {}'.format(token_info_version))
(name_len,), buf = unpack('!B', buf)
name, buf = unpack_len(name_len, buf)
(symbol_len,), buf = unpack('!B', buf)
symbol, buf = unpack_len(symbol_len, buf)
# Token name and symbol can be only utf-8 valid strings for now
decoded_name = decode_string_utf8(name, 'Token name')
decoded_symbol = decode_string_utf8(symbol, 'Token symbol')
return decoded_name, decoded_symbol, buf
def bytes_to_output_value(buf: bytes) -> Tuple[int, bytes]:
(value_high_byte, ), _ = unpack('!b', buf)
if value_high_byte < 0:
output_struct = '!q'
value_sign = -1
else:
output_struct = '!i'
value_sign = 1
try:
(signed_value, ), buf = unpack(output_struct, buf)
except StructError as e:
raise InvalidOutputValue('Invalid byte struct for output') from e
value = signed_value * value_sign
assert value >= 0
if value < _MAX_OUTPUT_VALUE_32 and value_high_byte < 0:
raise ValueError('Value fits in 4 bytes but is using 8 bytes')
return value, buf
def create_from_bytes(cls, buf: bytes) -> Tuple['TxOutput', bytes]:
""" Creates a TxOutput from a serialized output. Returns the output
and remaining bytes
"""
value, buf = bytes_to_output_value(buf)
(token_data, script_len), buf = unpack('!BH', buf)
script, buf = unpack_len(script_len, buf)
txout = cls(value, script, token_data)
return txout, buf
def create_from_bytes(cls, buf: bytes) -> Tuple['TxInput', bytes]:
""" Creates a TxInput from a serialized input. Returns the input
and remaining bytes
"""
input_tx_id, buf = unpack_len(TX_HASH_SIZE, buf)
(input_index, data_len), buf = unpack('!BH', buf)
input_data, buf = unpack_len(data_len, buf)
txin = cls(input_tx_id, input_index, input_data)
return txin, buf
def get_graph_fields_from_struct(self, buf: bytes) -> bytes:
""" Gets graph fields for a block from a buffer.
:param buf: Bytes of a serialized transaction
:type buf: bytes
:return: A buffer containing the remaining struct bytes
:rtype: bytes
:raises ValueError: when the sequence of bytes is incorect
"""
buf = super().get_graph_fields_from_struct(buf)
(data_bytes,), buf = unpack('!B', buf)
self.data, buf = unpack_len(data_bytes, buf)
return buf
def create_from_struct(cls, struct_bytes: bytes) -> 'Transaction':
try:
tx = cls()
buf = tx.get_fields_from_struct(struct_bytes)
if len(buf) != cls.SERIALIZATION_NONCE_SIZE:
raise ValueError('Invalid sequence of bytes')
[
tx.nonce,
], buf = unpack('!I', buf)
except struct.error:
raise ValueError('Invalid sequence of bytes')
tx.update_hash()
return tx
def get_funds_fields_from_struct(self, buf: bytes) -> bytes:
""" Gets all funds fields for a block from a buffer.
:param buf: Bytes of a serialized block
:type buf: bytes
:return: A buffer containing the remaining struct bytes
:rtype: bytes
:raises ValueError: when the sequence of bytes is incorect
"""
(self.version, outputs_len), buf = unpack(_FUNDS_FORMAT_STRING, buf)
for _ in range(outputs_len):
txout, buf = TxOutput.create_from_bytes(buf)
self.outputs.append(txout)
return buf
def get_graph_fields_from_struct(self, buf: bytes) -> bytes:
""" Gets all common graph fields for a Transaction and a Block from a buffer.
:param buf: Bytes of a serialized transaction
:type buf: bytes
:return: A buffer containing the remaining struct bytes
:rtype: bytes
:raises ValueError: when the sequence of bytes is incorect
"""
(self.weight, self.timestamp,
parents_len), buf = unpack(_GRAPH_FORMAT_STRING, buf)
for _ in range(parents_len):
parent, buf = unpack_len(TX_HASH_SIZE, buf) # 256bits
self.parents.append(parent)
return buf