def from_bytes(Tx, byte_string: bytes) -> 'Tx':
'''Instantiate a Tx object from a bytestring'''
# Get the version number
version = byte_string[0:4]
# Check if this is a witness tx
if byte_string[4:6] == riemann.network.SEGWIT_TX_FLAG:
tx_ins_num_loc = 6
flag = riemann.network.SEGWIT_TX_FLAG
else:
tx_ins_num_loc = 4
flag = None
# Get the length of the tx_in vector
tx_ins = []
tx_ins_num = VarInt.from_bytes(byte_string[tx_ins_num_loc:])
# `current` is the index of next read
current = tx_ins_num_loc + len(tx_ins_num)
# Deserialize all tx_ins
for _ in range(tx_ins_num.number):
tx_in = TxIn.from_bytes(byte_string[current:])
current += len(tx_in)
tx_ins.append(tx_in)
# Get the length of the tx_out vector
tx_outs = []
tx_outs_num = VarInt.from_bytes(byte_string[current:])
# Deserialize all outputs
current += len(tx_outs_num)
for _ in range(tx_outs_num.number):
tx_out = TxOut.from_bytes(byte_string[current:])
current += len(tx_out)
tx_outs.append(tx_out)
# Deserialize all witnesses if necessary
tx_witnesses: List[InputWitness] = []
if flag and len(byte_string[current:]) > 4:
tx_witnesses_num = tx_ins_num
for _ in range(tx_witnesses_num.number):
tx_witness = InputWitness.from_bytes(byte_string[current:])
current += len(tx_witness)
tx_witnesses.append(tx_witness)
# Get the lock time and return a complete tx
lock_time = byte_string[current:current + 4]
return Tx(
version=version,
flag=flag,
tx_ins=tx_ins,
tx_outs=tx_outs,
tx_witnesses=tx_witnesses,
lock_time=lock_time)
def from_bytes(TxIn, byte_string: bytes) -> 'TxIn':
'''
Parse a TxIn from a bytestring. Also available as from_hex
'''
outpoint = Outpoint.from_bytes(byte_string[:36])
# Extract the script sig length
script_sig_len = VarInt.from_bytes(byte_string[36:45])
# Extract the script sig
script_start = 36 + len(script_sig_len)
script_end = script_start + script_sig_len.number
script_sig = byte_string[script_start:script_end]
sequence = byte_string[script_end:script_end + 4]
# If the script-sig is blank, both stack and redeem are blank
if script_sig == b'':
stack_script = b''
redeem_script = b''
# If the outpoint is null (coinbase), don't try parsing the script sig
elif outpoint == Outpoint.null():
stack_script = script_sig
redeem_script = b''
# Parse the script sig into stack and redeem
else:
stack_script, redeem_script = TxIn._parse_script_sig(script_sig)
return TxIn(
outpoint=outpoint,
stack_script=stack_script,
redeem_script=redeem_script,
sequence=sequence)
def from_bytes(WitnessStackItem, byte_string: bytes) -> 'WitnessStackItem':
'''
Parse a WitnessStackItem from a bytestring. Also available as from_hex
'''
n = VarInt.from_bytes(byte_string)
item_start = len(n)
item_end = item_start + n.number
return WitnessStackItem(byte_string[item_start:item_end])
def from_bytes(InputWitness, byte_string):
stack_items = VarInt.from_bytes(byte_string)
item_start = len(stack_items)
items = []
while len(items) < stack_items.number:
item = WitnessStackItem.from_bytes(byte_string[item_start:])
item_start += len(item)
items.append(item)
return InputWitness(items)
def from_bytes(Tx, byte_string):
version = byte_string[0:4]
if byte_string[4:6] == riemann.network.SEGWIT_TX_FLAG:
tx_ins_num_loc = 6
flag = riemann.network.SEGWIT_TX_FLAG
else:
tx_ins_num_loc = 4
flag = None
tx_ins = []
tx_ins_num = VarInt.from_bytes(byte_string[tx_ins_num_loc:])
current = tx_ins_num_loc + len(tx_ins_num)
for _ in range(tx_ins_num.number):
tx_in = TxIn.from_bytes(byte_string[current:])
current += len(tx_in)
tx_ins.append(tx_in)
tx_outs = []
tx_outs_num = VarInt.from_bytes(byte_string[current:])
current += len(tx_outs_num)
for _ in range(tx_outs_num.number):
tx_out = TxOut.from_bytes(byte_string[current:])
current += len(tx_out)
tx_outs.append(tx_out)
if flag and len(byte_string[current:]) > 4:
tx_witnesses = []
tx_witnesses_num = tx_ins_num
for _ in range(tx_witnesses_num.number):
tx_witness = InputWitness.from_bytes(byte_string[current:])
current += len(tx_witness)
tx_witnesses.append(tx_witness)
else:
tx_witnesses = None
lock_time = byte_string[current:current + 4]
return Tx(version=version,
flag=flag,
tx_ins=tx_ins,
tx_outs=tx_outs,
tx_witnesses=tx_witnesses,
lock_time=lock_time)
def from_bytes(TxOut, byte_string):
n = VarInt.from_bytes(byte_string[8:])
script_start = 8 + len(n)
script_end = script_start + n.number
if n.number < 0xfc:
return TxOut(value=byte_string[:8],
output_script=byte_string[script_start:script_end])
else:
raise NotImplementedError(
'No support for abnormally long pk_scripts.')
def from_bytes(InputWitness, byte_string: bytes) -> 'InputWitness':
'''
Parse an InputWitness from a bytestring. Also available as from_hex
'''
stack_items = VarInt.from_bytes(byte_string)
item_start = len(stack_items)
items: List[WitnessStackItem] = []
while len(items) < stack_items.number:
item = WitnessStackItem.from_bytes(byte_string[item_start:])
item_start += len(item)
items.append(item)
return InputWitness(items)
def from_bytes(TxOut, byte_string: bytes) -> 'TxOut':
'''
Parse a TxOut from a bytestring. Also available as from_hex
'''
n = VarInt.from_bytes(byte_string[8:])
script_start = 8 + len(n)
script_end = script_start + n.number
if n.number < 0xfc:
return TxOut(
value=byte_string[:8],
output_script=byte_string[script_start:script_end])
else:
raise NotImplementedError(
'No support for abnormally long pk_scripts.')
def _sighash_prep(self, index: int, script: bytes) -> 'Tx':
'''
Sighashes suck
Performs the sighash setup described here:
https://en.bitcoin.it/wiki/OP_CHECKSIG#How_it_works
https://bitcoin.stackexchange.com/questions/3374/how-to-redeem-a-basic-tx
We save on complexity by refusing to support OP_CODESEPARATOR
'''
# 0 out scripts in tx_ins
copy_tx_ins = [tx_in.copy(stack_script=b'', redeem_script=b'')
for tx_in in self.tx_ins]
# NB: The script for the current transaction input in txCopy is set to
# subScript (lead in by its length as a var-integer encoded!)
to_strip = VarInt.from_bytes(script)
copy_tx_ins[index] = \
copy_tx_ins[index].copy(redeem_script=script[len(to_strip):])
return self.copy(tx_ins=copy_tx_ins)
def from_bytes(TxIn, byte_string):
'''
byte_string -> TxIn
parses a TxIn from a byte-like object
'''
outpoint = Outpoint.from_bytes(byte_string[:36])
script_sig_len = VarInt.from_bytes(byte_string[36:45])
script_start = 36 + len(script_sig_len)
script_end = script_start + script_sig_len.number
script_sig = byte_string[script_start:script_end]
sequence = byte_string[script_end:script_end + 4]
if script_sig == b'':
stack_script = b''
redeem_script = b''
else:
stack_script, redeem_script = TxIn._parse_script_sig(script_sig)
return TxIn(outpoint=outpoint,
stack_script=stack_script,
redeem_script=redeem_script,
sequence=sequence)
def from_bytes(WitnessStackItem, byte_string):
n = VarInt.from_bytes(byte_string)
item_start = len(n)
item_end = item_start + n.number
return WitnessStackItem(byte_string[item_start:item_end])