forked from LBRYCommunity/lbry-sdk
424 lines
13 KiB
Python
424 lines
13 KiB
Python
from itertools import chain
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from binascii import hexlify
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from collections import namedtuple
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from typing import List
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from torba.bcd_data_stream import BCDataStream
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from torba.util import subclass_tuple
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# bitcoin opcodes
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OP_0 = 0x00
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OP_1 = 0x51
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OP_16 = 0x60
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OP_VERIFY = 0x69
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OP_DUP = 0x76
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OP_HASH160 = 0xa9
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OP_EQUALVERIFY = 0x88
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OP_CHECKSIG = 0xac
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OP_CHECKMULTISIG = 0xae
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OP_EQUAL = 0x87
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OP_PUSHDATA1 = 0x4c
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OP_PUSHDATA2 = 0x4d
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OP_PUSHDATA4 = 0x4e
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OP_RETURN = 0x6a
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OP_2DROP = 0x6d
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OP_DROP = 0x75
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# template matching opcodes (not real opcodes)
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# base class for PUSH_DATA related opcodes
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# pylint: disable=invalid-name
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PUSH_DATA_OP = namedtuple('PUSH_DATA_OP', 'name')
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# opcode for variable length strings
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# pylint: disable=invalid-name
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PUSH_SINGLE = subclass_tuple('PUSH_SINGLE', PUSH_DATA_OP)
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# opcode for variable size integers
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# pylint: disable=invalid-name
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PUSH_INTEGER = subclass_tuple('PUSH_INTEGER', PUSH_DATA_OP)
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# opcode for variable number of variable length strings
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# pylint: disable=invalid-name
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PUSH_MANY = subclass_tuple('PUSH_MANY', PUSH_DATA_OP)
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# opcode with embedded subscript parsing
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# pylint: disable=invalid-name
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PUSH_SUBSCRIPT = namedtuple('PUSH_SUBSCRIPT', 'name template')
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def is_push_data_opcode(opcode):
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return isinstance(opcode, (PUSH_DATA_OP, PUSH_SUBSCRIPT))
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def is_push_data_token(token):
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return 1 <= token <= OP_PUSHDATA4
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def push_data(data):
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size = len(data)
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if size < OP_PUSHDATA1:
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yield BCDataStream.uint8.pack(size)
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elif size <= 0xFF:
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yield BCDataStream.uint8.pack(OP_PUSHDATA1)
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yield BCDataStream.uint8.pack(size)
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elif size <= 0xFFFF:
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yield BCDataStream.uint8.pack(OP_PUSHDATA2)
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yield BCDataStream.uint16.pack(size)
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else:
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yield BCDataStream.uint8.pack(OP_PUSHDATA4)
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yield BCDataStream.uint32.pack(size)
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yield data
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def read_data(token, stream):
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if token < OP_PUSHDATA1:
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return stream.read(token)
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if token == OP_PUSHDATA1:
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return stream.read(stream.read_uint8())
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if token == OP_PUSHDATA2:
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return stream.read(stream.read_uint16())
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return stream.read(stream.read_uint32())
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# opcode for OP_1 - OP_16
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# pylint: disable=invalid-name
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SMALL_INTEGER = namedtuple('SMALL_INTEGER', 'name')
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def is_small_integer(token):
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return OP_1 <= token <= OP_16
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def push_small_integer(num):
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assert 1 <= num <= 16
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yield BCDataStream.uint8.pack(OP_1 + (num - 1))
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def read_small_integer(token):
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return (token - OP_1) + 1
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class Token(namedtuple('Token', 'value')):
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__slots__ = ()
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def __repr__(self):
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name = None
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for var_name, var_value in globals().items():
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if var_name.startswith('OP_') and var_value == self.value:
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name = var_name
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break
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return name or self.value
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class DataToken(Token):
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__slots__ = ()
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def __repr__(self):
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return '"{}"'.format(hexlify(self.value))
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class SmallIntegerToken(Token):
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__slots__ = ()
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def __repr__(self):
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return 'SmallIntegerToken({})'.format(self.value)
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def token_producer(source):
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token = source.read_uint8()
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while token is not None:
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if is_push_data_token(token):
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yield DataToken(read_data(token, source))
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elif is_small_integer(token):
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yield SmallIntegerToken(read_small_integer(token))
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else:
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yield Token(token)
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token = source.read_uint8()
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def tokenize(source):
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return list(token_producer(source))
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class ScriptError(Exception):
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""" General script handling error. """
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class ParseError(ScriptError):
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""" Script parsing error. """
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class Parser:
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def __init__(self, opcodes, tokens):
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self.opcodes = opcodes
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self.tokens = tokens
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self.values = {}
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self.token_index = 0
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self.opcode_index = 0
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def parse(self):
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while self.token_index < len(self.tokens) and self.opcode_index < len(self.opcodes):
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token = self.tokens[self.token_index]
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opcode = self.opcodes[self.opcode_index]
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if isinstance(token, DataToken):
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if isinstance(opcode, (PUSH_SINGLE, PUSH_INTEGER, PUSH_SUBSCRIPT)):
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self.push_single(opcode, token.value)
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elif isinstance(opcode, PUSH_MANY):
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self.consume_many_non_greedy()
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else:
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raise ParseError("DataToken found but opcode was '{}'.".format(opcode))
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elif isinstance(token, SmallIntegerToken):
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if isinstance(opcode, SMALL_INTEGER):
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self.values[opcode.name] = token.value
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else:
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raise ParseError("SmallIntegerToken found but opcode was '{}'.".format(opcode))
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elif token.value == opcode:
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pass
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else:
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raise ParseError("Token is '{}' and opcode is '{}'.".format(token.value, opcode))
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self.token_index += 1
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self.opcode_index += 1
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if self.token_index < len(self.tokens):
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raise ParseError("Parse completed without all tokens being consumed.")
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if self.opcode_index < len(self.opcodes):
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raise ParseError("Parse completed without all opcodes being consumed.")
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return self
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def consume_many_non_greedy(self):
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""" Allows PUSH_MANY to consume data without being greedy
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in cases when one or more PUSH_SINGLEs follow a PUSH_MANY. This will
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prioritize giving all PUSH_SINGLEs some data and only after that
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subsume the rest into PUSH_MANY.
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"""
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token_values = []
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while self.token_index < len(self.tokens):
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token = self.tokens[self.token_index]
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if not isinstance(token, DataToken):
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self.token_index -= 1
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break
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token_values.append(token.value)
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self.token_index += 1
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push_opcodes = []
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push_many_count = 0
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while self.opcode_index < len(self.opcodes):
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opcode = self.opcodes[self.opcode_index]
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if not is_push_data_opcode(opcode):
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self.opcode_index -= 1
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break
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if isinstance(opcode, PUSH_MANY):
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push_many_count += 1
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push_opcodes.append(opcode)
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self.opcode_index += 1
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if push_many_count > 1:
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raise ParseError(
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"Cannot have more than one consecutive PUSH_MANY, as there is no way to tell which"
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" token value should go into which PUSH_MANY."
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)
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if len(push_opcodes) > len(token_values):
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raise ParseError(
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"Not enough token values to match all of the PUSH_MANY and PUSH_SINGLE opcodes."
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)
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many_opcode = push_opcodes.pop(0)
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# consume data into PUSH_SINGLE opcodes, working backwards
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for opcode in reversed(push_opcodes):
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self.push_single(opcode, token_values.pop())
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# finally PUSH_MANY gets everything that's left
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self.values[many_opcode.name] = token_values
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def push_single(self, opcode, value):
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if isinstance(opcode, PUSH_SINGLE):
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self.values[opcode.name] = value
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elif isinstance(opcode, PUSH_INTEGER):
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self.values[opcode.name] = int.from_bytes(value, 'little')
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elif isinstance(opcode, PUSH_SUBSCRIPT):
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self.values[opcode.name] = Script.from_source_with_template(value, opcode.template)
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else:
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raise ParseError("Not a push single or subscript: {}".format(opcode))
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class Template:
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__slots__ = 'name', 'opcodes'
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def __init__(self, name, opcodes):
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self.name = name
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self.opcodes = opcodes
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def parse(self, tokens):
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return Parser(self.opcodes, tokens).parse().values
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def generate(self, values):
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source = BCDataStream()
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for opcode in self.opcodes:
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if isinstance(opcode, PUSH_SINGLE):
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data = values[opcode.name]
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source.write_many(push_data(data))
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elif isinstance(opcode, PUSH_INTEGER):
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data = values[opcode.name]
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source.write_many(push_data(
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data.to_bytes((data.bit_length() + 7) // 8, byteorder='little')
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))
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elif isinstance(opcode, PUSH_SUBSCRIPT):
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data = values[opcode.name]
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source.write_many(push_data(data.source))
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elif isinstance(opcode, PUSH_MANY):
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for data in values[opcode.name]:
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source.write_many(push_data(data))
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elif isinstance(opcode, SMALL_INTEGER):
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data = values[opcode.name]
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source.write_many(push_small_integer(data))
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else:
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source.write_uint8(opcode)
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return source.get_bytes()
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class Script:
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__slots__ = 'source', 'template', 'values'
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templates: List[Template] = []
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def __init__(self, source=None, template=None, values=None, template_hint=None):
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self.source = source
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self.template = template
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self.values = values
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if source:
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self.parse(template_hint)
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elif template and values:
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self.generate()
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@property
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def tokens(self):
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return tokenize(BCDataStream(self.source))
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@classmethod
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def from_source_with_template(cls, source, template):
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return cls(source, template_hint=template)
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def parse(self, template_hint=None):
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tokens = self.tokens
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for template in chain((template_hint,), self.templates):
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if not template:
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continue
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try:
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self.values = template.parse(tokens)
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self.template = template
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return
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except ParseError:
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continue
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raise ValueError('No matching templates for source: {}'.format(hexlify(self.source)))
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def generate(self):
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self.source = self.template.generate(self.values)
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class BaseInputScript(Script):
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""" Input / redeem script templates (aka scriptSig) """
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__slots__ = ()
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REDEEM_PUBKEY = Template('pubkey', (
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PUSH_SINGLE('signature'),
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))
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REDEEM_PUBKEY_HASH = Template('pubkey_hash', (
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PUSH_SINGLE('signature'), PUSH_SINGLE('pubkey')
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))
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REDEEM_SCRIPT = Template('script', (
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SMALL_INTEGER('signatures_count'), PUSH_MANY('pubkeys'), SMALL_INTEGER('pubkeys_count'),
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OP_CHECKMULTISIG
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))
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REDEEM_SCRIPT_HASH = Template('script_hash', (
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OP_0, PUSH_MANY('signatures'), PUSH_SUBSCRIPT('script', REDEEM_SCRIPT)
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))
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templates = [
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REDEEM_PUBKEY,
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REDEEM_PUBKEY_HASH,
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REDEEM_SCRIPT_HASH,
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REDEEM_SCRIPT
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]
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@classmethod
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def redeem_pubkey_hash(cls, signature, pubkey):
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return cls(template=cls.REDEEM_PUBKEY_HASH, values={
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'signature': signature,
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'pubkey': pubkey
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})
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@classmethod
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def redeem_script_hash(cls, signatures, pubkeys):
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return cls(template=cls.REDEEM_SCRIPT_HASH, values={
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'signatures': signatures,
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'script': cls.redeem_script(signatures, pubkeys)
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})
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@classmethod
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def redeem_script(cls, signatures, pubkeys):
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return cls(template=cls.REDEEM_SCRIPT, values={
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'signatures_count': len(signatures),
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'pubkeys': pubkeys,
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'pubkeys_count': len(pubkeys)
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})
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class BaseOutputScript(Script):
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__slots__ = ()
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# output / payment script templates (aka scriptPubKey)
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PAY_PUBKEY_FULL = Template('pay_pubkey_full', (
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PUSH_SINGLE('pubkey'), OP_CHECKSIG
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))
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PAY_PUBKEY_HASH = Template('pay_pubkey_hash', (
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OP_DUP, OP_HASH160, PUSH_SINGLE('pubkey_hash'), OP_EQUALVERIFY, OP_CHECKSIG
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))
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PAY_SCRIPT_HASH = Template('pay_script_hash', (
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OP_HASH160, PUSH_SINGLE('script_hash'), OP_EQUAL
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))
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RETURN_DATA = Template('return_data', (
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OP_RETURN, PUSH_SINGLE('data')
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))
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templates = [
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PAY_PUBKEY_FULL,
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PAY_PUBKEY_HASH,
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PAY_SCRIPT_HASH,
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RETURN_DATA
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]
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@classmethod
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def pay_pubkey_hash(cls, pubkey_hash):
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return cls(template=cls.PAY_PUBKEY_HASH, values={
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'pubkey_hash': pubkey_hash
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})
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@classmethod
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def pay_script_hash(cls, script_hash):
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return cls(template=cls.PAY_SCRIPT_HASH, values={
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'script_hash': script_hash
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})
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@property
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def is_pay_pubkey(self):
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return self.template.name.endswith('pay_pubkey_full')
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@property
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def is_pay_pubkey_hash(self):
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return self.template.name.endswith('pay_pubkey_hash')
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@property
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def is_pay_script_hash(self):
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return self.template.name.endswith('pay_script_hash')
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@property
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def is_return_data(self):
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return self.template.name.endswith('return_data')
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