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 get_type(script):
"""https://github.com/bitcoin/bitcoin/blob/5961b23898ee7c0af2626c46d5d70e80136578d3/src/script/script.cpp#L202"""
script = hex_to_bytes(script) if isinstance(script, str) else script
if script.startswith(OP.HASH160.byte + OP.PUSH20.byte) and script.endswith(
OP.EQUAL.byte) and len(script) == 23:
return TX.P2SH
elif script.startswith(OP.DUP.byte + OP.HASH160.byte) and script.endswith(
OP.EQUALVERIFY.byte + OP.CHECKSIG.byte) and len(script) == 25:
return TX.P2PKH
elif script.startswith(b'\x00' + OP.PUSH32.byte) and len(script) == 34:
return TX.P2WSH
elif script.startswith(b'\x00' + OP.PUSH20.byte) and len(script) == 22:
return TX.P2WPKH
elif script.startswith(OP.PUSH65.byte + b'\x04') and script.endswith(
OP.CHECKSIG.byte) and len(script) == 67: # uncompressed PK
return TX.P2PK
elif script.startswith((b'\x21\x03', b'\x21\x02')) and script.endswith(
OP.CHECKSIG.byte) and len(script) == 35: # compressed PK
return TX.P2PK
else:
raise ScriptValidationError(
f"Unknown script type: {bytes_to_hex(script)}")
def version_byte(script):
if not is_witness_program(script):
raise ScriptValidationError("Script is not a witness program")
return script[0]
def witness_program(script):
if not is_witness_program(script):
raise ScriptValidationError("Script is not a witness program")
return script[2:]