#!/usr/bin/env python3 # Copyright (c) 2015-2016 The Bitcoin Core developers # Distributed under the MIT software license, see the accompanying # file COPYING or http://www.opensource.org/licenses/mit-license.php. """Functionality to build scripts, as well as SignatureHash(). This file is modified from python-bitcoinlib. """ from .bignum import bn2vch from binascii import hexlify import hashlib import struct from .messages import ( CTransaction, CTxOut, hash256, ser_string, ser_uint256, sha256, uint256_from_str, ) MAX_SCRIPT_ELEMENT_SIZE = 520 OPCODE_NAMES = {} def hash160(s): return hashlib.new('ripemd160', sha256(s)).digest() _opcode_instances = [] class CScriptOp(int): """A single script opcode""" __slots__ = () @staticmethod def encode_op_pushdata(d): """Encode a PUSHDATA op, returning bytes""" if len(d) < 0x4c: # OP_PUSHDATA return b'' + bytes([len(d)]) + d elif len(d) <= 0xff: # OP_PUSHDATA1 return b'\x4c' + bytes([len(d)]) + d elif len(d) <= 0xffff: return b'\x4d' + struct.pack(b'>= 8 if r[-1] & 0x80: r.append(0x80 if neg else 0) elif neg: r[-1] |= 0x80 return bytes(bytes([len(r)]) + r) class CScript(bytes): """Serialized script A bytes subclass, so you can use this directly whenever bytes are accepted. Note that this means that indexing does *not* work - you'll get an index by byte rather than opcode. This format was chosen for efficiency so that the general case would not require creating a lot of little CScriptOP objects. iter(script) however does iterate by opcode. """ __slots__ = () @classmethod def __coerce_instance(cls, other): # Coerce other into bytes if isinstance(other, CScriptOp): other = bytes([other]) elif isinstance(other, CScriptNum): if (other.value == 0): other = bytes([CScriptOp(OP_0)]) else: other = CScriptNum.encode(other) elif isinstance(other, int): if 0 <= other <= 16: other = bytes([CScriptOp.encode_op_n(other)]) elif other == -1: other = bytes([OP_1NEGATE]) else: other = CScriptOp.encode_op_pushdata(bn2vch(other)) elif isinstance(other, (bytes, bytearray)): other = CScriptOp.encode_op_pushdata(other) return other def __add__(self, other): # Do the coercion outside of the try block so that errors in it are # noticed. other = self.__coerce_instance(other) try: # bytes.__add__ always returns bytes instances unfortunately return CScript(super(CScript, self).__add__(other)) except TypeError: raise TypeError( 'Can not add a {!r} instance to a CScript'.format(other.__class__)) def join(self, iterable): # join makes no sense for a CScript() raise NotImplementedError def __new__(cls, value=b''): if isinstance(value, bytes) or isinstance(value, bytearray): return super(CScript, cls).__new__(cls, value) else: def coerce_iterable(iterable): for instance in iterable: yield cls.__coerce_instance(instance) # Annoyingly on both python2 and python3 bytes.join() always # returns a bytes instance even when subclassed. return super(CScript, cls).__new__(cls, b''.join(coerce_iterable(value))) def raw_iter(self): """Raw iteration Yields tuples of (opcode, data, sop_idx) so that the different possible PUSHDATA encodings can be accurately distinguished, as well as determining the exact opcode byte indexes. (sop_idx) """ i = 0 while i < len(self): sop_idx = i opcode = self[i] i += 1 if opcode > OP_PUSHDATA4: yield (opcode, None, sop_idx) else: datasize = None pushdata_type = None if opcode < OP_PUSHDATA1: pushdata_type = 'PUSHDATA({})'.format(opcode) datasize = opcode elif opcode == OP_PUSHDATA1: pushdata_type = 'PUSHDATA1' if i >= len(self): raise CScriptInvalidError( 'PUSHDATA1: missing data length') datasize = self[i] i += 1 elif opcode == OP_PUSHDATA2: pushdata_type = 'PUSHDATA2' if i + 1 >= len(self): raise CScriptInvalidError( 'PUSHDATA2: missing data length') datasize = self[i] + (self[i + 1] << 8) i += 2 elif opcode == OP_PUSHDATA4: pushdata_type = 'PUSHDATA4' if i + 3 >= len(self): raise CScriptInvalidError( 'PUSHDATA4: missing data length') datasize = self[i] + (self[i + 1] << 8) + \ (self[i + 2] << 16) + (self[i + 3] << 24) i += 4 else: assert False # shouldn't happen data = bytes(self[i:i + datasize]) # Check for truncation if len(data) < datasize: raise CScriptTruncatedPushDataError( '{}: truncated data'.format(pushdata_type, data)) i += datasize yield (opcode, data, sop_idx) def __iter__(self): """'Cooked' iteration Returns either a CScriptOP instance, an integer, or bytes, as appropriate. See raw_iter() if you need to distinguish the different possible PUSHDATA encodings. """ for (opcode, data, sop_idx) in self.raw_iter(): if data is not None: yield data else: opcode = CScriptOp(opcode) if opcode.is_small_int(): yield opcode.decode_op_n() else: yield CScriptOp(opcode) def __repr__(self): def _repr(o): if isinstance(o, bytes): return "x('{}')".format(hexlify(o).decode('ascii')) else: return repr(o) ops = [] i = iter(self) while True: op = None try: op = _repr(next(i)) except CScriptTruncatedPushDataError as err: op = '{}...'.format(_repr(err.data), err) break except CScriptInvalidError as err: op = ''.format(err) break except StopIteration: break finally: if op is not None: ops.append(op) return "CScript([{}])".format(', '.join(ops)) def GetSigOpCount(self, fAccurate): """Get the SigOp count. fAccurate - Accurately count CHECKMULTISIG, see BIP16 for details. Note that this is consensus-critical. """ n = 0 lastOpcode = OP_INVALIDOPCODE for (opcode, data, sop_idx) in self.raw_iter(): if opcode in (OP_CHECKSIG, OP_CHECKSIGVERIFY): n += 1 elif opcode in (OP_CHECKMULTISIG, OP_CHECKMULTISIGVERIFY): if fAccurate and (OP_1 <= lastOpcode <= OP_16): n += opcode.decode_op_n() else: n += 20 lastOpcode = opcode return n SIGHASH_ALL = 1 SIGHASH_NONE = 2 SIGHASH_SINGLE = 3 SIGHASH_FORKID = 0x40 SIGHASH_ANYONECANPAY = 0x80 def FindAndDelete(script, sig): """Consensus critical, see FindAndDelete() in Satoshi codebase""" r = b'' last_sop_idx = sop_idx = 0 skip = True for (opcode, data, sop_idx) in script.raw_iter(): if not skip: r += script[last_sop_idx:sop_idx] last_sop_idx = sop_idx if script[sop_idx:sop_idx + len(sig)] == sig: skip = True else: skip = False if not skip: r += script[last_sop_idx:] return CScript(r) def SignatureHash(script, txTo, inIdx, hashtype): """Consensus-correct SignatureHash Returns (hash, err) to precisely match the consensus-critical behavior of the SIGHASH_SINGLE bug. (inIdx is *not* checked for validity) """ HASH_ONE = b'\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00' if inIdx >= len(txTo.vin): return (HASH_ONE, "inIdx {} out of range ({})".format(inIdx, len(txTo.vin))) txtmp = CTransaction(txTo) for txin in txtmp.vin: txin.scriptSig = b'' txtmp.vin[inIdx].scriptSig = FindAndDelete( script, CScript([OP_CODESEPARATOR])) if (hashtype & 0x1f) == SIGHASH_NONE: txtmp.vout = [] for i in range(len(txtmp.vin)): if i != inIdx: txtmp.vin[i].nSequence = 0 elif (hashtype & 0x1f) == SIGHASH_SINGLE: outIdx = inIdx if outIdx >= len(txtmp.vout): return (HASH_ONE, "outIdx {} out of range ({})".format(outIdx, len(txtmp.vout))) tmp = txtmp.vout[outIdx] txtmp.vout = [] for i in range(outIdx): txtmp.vout.append(CTxOut(-1)) txtmp.vout.append(tmp) for i in range(len(txtmp.vin)): if i != inIdx: txtmp.vin[i].nSequence = 0 if hashtype & SIGHASH_ANYONECANPAY: tmp = txtmp.vin[inIdx] txtmp.vin = [] txtmp.vin.append(tmp) s = txtmp.serialize() s += struct.pack(b"