lbry-sdk/torba/basetransaction.py
2018-06-13 23:00:53 -05:00

367 lines
13 KiB
Python

import six
import logging
from typing import List, Iterable, Generator
from binascii import hexlify
from twisted.internet import defer
import torba.baseaccount
import torba.baseledger
from torba.basescript import BaseInputScript, BaseOutputScript
from torba.coinselection import CoinSelector
from torba.constants import COIN
from torba.bcd_data_stream import BCDataStream
from torba.hash import sha256
from torba.util import ReadOnlyList
log = logging.getLogger()
NULL_HASH = b'\x00'*32
class InputOutput(object):
def __init__(self, txhash, index=None):
self._txhash = txhash # type: bytes
self.transaction = None # type: BaseTransaction
self.index = index # type: int
@property
def txhash(self):
if self._txhash is None:
self._txhash = self.transaction.hash
return self._txhash
@property
def size(self):
""" Size of this input / output in bytes. """
stream = BCDataStream()
self.serialize_to(stream)
return len(stream.get_bytes())
def serialize_to(self, stream):
raise NotImplemented
class BaseInput(InputOutput):
script_class = BaseInputScript
NULL_SIGNATURE = b'\x00'*72
NULL_PUBLIC_KEY = b'\x00'*33
def __init__(self, output_or_txhash_index, script, sequence=0xFFFFFFFF, txhash=None):
super(BaseInput, self).__init__(txhash)
if isinstance(output_or_txhash_index, BaseOutput):
self.output = output_or_txhash_index # type: BaseOutput
self.output_txhash = self.output.txhash
self.output_index = self.output.index
else:
self.output = None # type: BaseOutput
self.output_txhash, self.output_index = output_or_txhash_index
self.sequence = sequence
self.is_coinbase = self.output_txhash == NULL_HASH
self.coinbase = script if self.is_coinbase else None
self.script = script if not self.is_coinbase else None # type: BaseInputScript
@classmethod
def spend(cls, output):
""" Create an input to spend the output."""
assert output.script.is_pay_pubkey_hash, 'Attempting to spend unsupported output.'
script = cls.script_class.redeem_pubkey_hash(cls.NULL_SIGNATURE, cls.NULL_PUBLIC_KEY)
return cls(output, script)
@property
def amount(self):
""" Amount this input adds to the transaction. """
if self.output is None:
raise ValueError('Cannot get input value without referenced output.')
return self.output.amount
@classmethod
def deserialize_from(cls, stream):
txhash = stream.read(32)
index = stream.read_uint32()
script = stream.read_string()
sequence = stream.read_uint32()
return cls(
(txhash, index),
cls.script_class(script) if not txhash == NULL_HASH else script,
sequence
)
def serialize_to(self, stream, alternate_script=None):
stream.write(self.output_txhash)
stream.write_uint32(self.output_index)
if alternate_script is not None:
stream.write_string(alternate_script)
else:
if self.is_coinbase:
stream.write_string(self.coinbase)
else:
stream.write_string(self.script.source)
stream.write_uint32(self.sequence)
class BaseOutputEffectiveAmountEstimator(object):
__slots__ = 'coin', 'txi', 'txo', 'fee', 'effective_amount'
def __init__(self, ledger, txo): # type: (torba.baseledger.BaseLedger, BaseOutput) -> None
self.txo = txo
self.txi = ledger.transaction_class.input_class.spend(txo)
self.fee = ledger.get_input_output_fee(self.txi)
self.effective_amount = txo.amount - self.fee
def __lt__(self, other):
return self.effective_amount < other.effective_amount
class BaseOutput(InputOutput):
script_class = BaseOutputScript
estimator_class = BaseOutputEffectiveAmountEstimator
def __init__(self, amount, script, txhash=None, index=None):
super(BaseOutput, self).__init__(txhash, index)
self.amount = amount # type: int
self.script = script # type: BaseOutputScript
def get_estimator(self, ledger):
return self.estimator_class(ledger, self)
@classmethod
def pay_pubkey_hash(cls, amount, pubkey_hash):
return cls(amount, cls.script_class.pay_pubkey_hash(pubkey_hash))
@classmethod
def deserialize_from(cls, stream):
return cls(
amount=stream.read_uint64(),
script=cls.script_class(stream.read_string())
)
def serialize_to(self, stream):
stream.write_uint64(self.amount)
stream.write_string(self.script.source)
class BaseTransaction:
input_class = BaseInput
output_class = BaseOutput
def __init__(self, raw=None, version=1, locktime=0):
self._raw = raw
self._hash = None
self._id = None
self.version = version # type: int
self.locktime = locktime # type: int
self._inputs = [] # type: List[BaseInput]
self._outputs = [] # type: List[BaseOutput]
if raw is not None:
self._deserialize()
@property
def hex_id(self):
return hexlify(self.id)
@property
def id(self):
if self._id is None:
self._id = self.hash[::-1]
return self._id
@property
def hash(self):
if self._hash is None:
self._hash = sha256(sha256(self.raw))
return self._hash
@property
def raw(self):
if self._raw is None:
self._raw = self._serialize()
return self._raw
def _reset(self):
self._id = None
self._hash = None
self._raw = None
@property
def inputs(self): # type: () -> ReadOnlyList[BaseInput]
return ReadOnlyList(self._inputs)
@property
def outputs(self): # type: () -> ReadOnlyList[BaseOutput]
return ReadOnlyList(self._outputs)
def _add(self, new_ios, existing_ios):
for txio in new_ios:
txio.transaction = self
txio.index = len(existing_ios)
existing_ios.append(txio)
self._reset()
return self
def add_inputs(self, inputs):
return self._add(inputs, self._inputs)
def add_outputs(self, outputs):
return self._add(outputs, self._outputs)
@property
def fee(self):
""" Fee that will actually be paid."""
return self.input_sum - self.output_sum
@property
def size(self):
""" Size in bytes of the entire transaction. """
return len(self.raw)
@property
def base_size(self):
""" Size in bytes of transaction meta data and all outputs; without inputs. """
return len(self._serialize(with_inputs=False))
def _serialize(self, with_inputs=True):
stream = BCDataStream()
stream.write_uint32(self.version)
if with_inputs:
stream.write_compact_size(len(self._inputs))
for txin in self._inputs:
txin.serialize_to(stream)
stream.write_compact_size(len(self._outputs))
for txout in self._outputs:
txout.serialize_to(stream)
stream.write_uint32(self.locktime)
return stream.get_bytes()
def _serialize_for_signature(self, signing_input):
stream = BCDataStream()
stream.write_uint32(self.version)
stream.write_compact_size(len(self._inputs))
for i, txin in enumerate(self._inputs):
if signing_input == i:
txin.serialize_to(stream, txin.output.script.source)
else:
txin.serialize_to(stream, b'')
stream.write_compact_size(len(self._outputs))
for txout in self._outputs:
txout.serialize_to(stream)
stream.write_uint32(self.locktime)
stream.write_uint32(self.signature_hash_type(1)) # signature hash type: SIGHASH_ALL
return stream.get_bytes()
def _deserialize(self):
if self._raw is not None:
stream = BCDataStream(self._raw)
self.version = stream.read_uint32()
input_count = stream.read_compact_size()
self.add_inputs([
self.input_class.deserialize_from(stream) for _ in range(input_count)
])
output_count = stream.read_compact_size()
self.add_outputs([
self.output_class.deserialize_from(stream) for _ in range(output_count)
])
self.locktime = stream.read_uint32()
@classmethod
@defer.inlineCallbacks
def get_effective_amount_estimators(cls, funding_accounts):
# type: (Iterable[torba.baseaccount.BaseAccount]) -> Generator[BaseOutputEffectiveAmountEstimator]
estimators = []
for account in funding_accounts:
utxos = yield account.ledger.get_unspent_outputs(account)
for utxo in utxos:
estimators.append(utxo.get_estimator(account.ledger))
defer.returnValue(estimators)
@classmethod
def ensure_all_have_same_ledger(cls, funding_accounts, change_account=None):
# type: (Iterable[torba.baseaccount.BaseAccount], torba.baseaccount.BaseAccount) -> torba.baseledger.BaseLedger
ledger = None
for account in funding_accounts:
if ledger is None:
ledger = account.ledger
if ledger != account.ledger:
raise ValueError(
'All funding accounts used to create a transaction must be on the same ledger.'
)
if change_account is not None and change_account.ledger != ledger:
raise ValueError('Change account must use same ledger as funding accounts.')
return ledger
@classmethod
@defer.inlineCallbacks
def pay(cls, outputs, funding_accounts, change_account):
# type: (List[BaseOutput], List[torba.baseaccount.BaseAccount], torba.baseaccount.BaseAccount) -> BaseTransaction
""" Efficiently spend utxos from funding_accounts to cover the new outputs. """
tx = cls().add_outputs(outputs)
ledger = cls.ensure_all_have_same_ledger(funding_accounts, change_account)
amount = tx.output_sum + ledger.get_transaction_base_fee(tx)
txos = yield cls.get_effective_amount_estimators(funding_accounts)
selector = CoinSelector(
txos, amount,
ledger.get_input_output_fee(
cls.output_class.pay_pubkey_hash(COIN, NULL_HASH)
)
)
spendables = selector.select()
if not spendables:
raise ValueError('Not enough funds to cover this transaction.')
spent_sum = sum(s.effective_amount for s in spendables)
if spent_sum > amount:
change_address = yield change_account.change.get_or_create_usable_address()
change_hash160 = change_account.ledger.address_to_hash160(change_address)
change_amount = spent_sum - amount
tx.add_outputs([cls.output_class.pay_pubkey_hash(change_amount, change_hash160)])
tx.add_inputs([s.txi for s in spendables])
yield tx.sign(funding_accounts)
defer.returnValue(tx)
@classmethod
def liquidate(cls, assets, funding_accounts, change_account):
""" Spend assets (utxos) supplementing with funding_accounts if fee is higher than asset value. """
def signature_hash_type(self, hash_type):
return hash_type
@defer.inlineCallbacks
def sign(self, funding_accounts): # type: (Iterable[torba.baseaccount.BaseAccount]) -> BaseTransaction
ledger = self.ensure_all_have_same_ledger(funding_accounts)
for i, txi in enumerate(self._inputs):
txo_script = txi.output.script
if txo_script.is_pay_pubkey_hash:
address = ledger.hash160_to_address(txo_script.values['pubkey_hash'])
private_key = yield ledger.get_private_key_for_address(address)
tx = self._serialize_for_signature(i)
txi.script.values['signature'] = \
private_key.sign(tx) + six.int2byte(self.signature_hash_type(1))
txi.script.values['pubkey'] = private_key.public_key.pubkey_bytes
txi.script.generate()
else:
raise NotImplementedError("Don't know how to spend this output.")
self._reset()
def sort(self):
# See https://github.com/kristovatlas/rfc/blob/master/bips/bip-li01.mediawiki
self._inputs.sort(key=lambda i: (i['prevout_hash'], i['prevout_n']))
self._outputs.sort(key=lambda o: (o[2], pay_script(o[0], o[1])))
@property
def input_sum(self):
return sum(i.amount for i in self.inputs)
@property
def output_sum(self):
return sum(o.amount for o in self.outputs)