def __init__(self, tx, index):
self.tx = tx
self.index = index
self.input = tx.inputs[index]
self.output = self.input.ref()
self.scriptPubKey = self.output.script
self.scriptSig = self.input.script
self.script = self.scriptSig + self.scriptPubKey
self.stack = []
self.OPS = {OP(i): partial(self.OP_PUSH, i) for i in range(1, 76)}
self.OPS.update(
{OP(i): partial(self.push, i - 80)
for i in range(81, 97)})
def depush(script: bytes) -> bytes:
if len(script) == 0:
raise ScriptValidationError('Empty script')
push_byte, script = script[0], script[1:]
op = OP(push_byte)
if push_byte not in range(1, 76):
raise ScriptValidationError(
f'Script does not start with a PUSH opcode: {op}')
if len(script) < push_byte:
raise ScriptValidationError('Script too short')
elif len(script) > push_byte:
raise ScriptValidationError('Script too long')
return script
def _receive(self, value: int):
"""Creates an output that sends to this address"""
addr_type = self.type()
output = Output(value=value, script=b'')
if addr_type == ADDRESS.P2PKH:
address = base58.decode(self.address).rjust(25, b'\x00')
keyhash = address[1:-4]
output.script = OP.DUP.byte + OP.HASH160.byte + push(
keyhash) + OP.EQUALVERIFY.byte + OP.CHECKSIG.byte
elif addr_type == ADDRESS.P2SH:
address = base58.decode(self.address).rjust(25, b'\x00')
scripthash = address[1:-4]
output.script = OP.HASH160.byte + push(scripthash) + OP.EQUAL.byte
elif addr_type in (ADDRESS.P2WPKH, ADDRESS.P2WSH):
witness_version, witness_program = bech32.decode(
network('hrp'), self.address)
output.script = OP(bytes_to_int(
witness_byte(witness_version))).byte + push(
bytes(witness_program))
else:
raise ValidationError(f"Cannot create output of type {addr_type}")
return output
def asm(script):
"""Turns a script into a symbolic representation"""
if isinstance(script, str):
script = hex_to_bytes(script)
else:
script = copy(script)
def read(n):
nonlocal script
data = script[:n]
assert data or n == 0, 'EOF'
script = script[n:]
return data
results = []
while script:
byte = bytes_to_int(read(1))
op = OP(byte)
if byte in range(1, 76):
results.append(bytes_to_hex(read(byte)))
else:
results.append(str(op))
return ' '.join(results)
def step(self):
"""Executes one script operation"""
byte = bytes_to_int(self.read(1))
opcode = OP(byte)
self.op(opcode)