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#!/usr/bin/env python3
# Copyright (c) 2020 The Bitcoin Core developers
# Distributed under the MIT software license, see the accompanying
# file COPYING or http://www.opensource.org/licenses/mit-license.php.
"""A limited-functionality wallet, which may replace a real wallet in tests"""
from decimal import Decimal
from enum import Enum
from typing import Optional
from test_framework.address import ADDRESS_BCRT1_P2WSH_OP_TRUE
from test_framework.key import ECKey
from test_framework.messages import (
COIN,
COutPoint,
CTransaction,
CTxIn,
CTxInWitness,
CTxOut,
)
from test_framework.script import (
CScript,
LegacySignatureHash,
OP_CHECKSIG,
OP_TRUE,
OP_NOP,
SIGHASH_ALL,
)
from test_framework.util import (
assert_equal,
hex_str_to_bytes,
satoshi_round,
)
class MiniWalletMode(Enum):
"""Determines the transaction type the MiniWallet is creating and spending.
For most purposes, the default mode ADDRESS_OP_TRUE should be sufficient;
it simply uses a fixed bech32 P2WSH address whose coins are spent with a
witness stack of OP_TRUE, i.e. following an anyone-can-spend policy.
However, if the transactions need to be modified by the user (e.g. prepending
scriptSig for testing opcodes that are activated by a soft-fork), or the txs
should contain an actual signature, the raw modes RAW_OP_TRUE and RAW_P2PK
can be useful. Summary of modes:
| output | | tx is | can modify | needs
mode | description | address | standard | scriptSig | signing
----------------+-------------------+-----------+----------+------------+----------
ADDRESS_OP_TRUE | anyone-can-spend | bech32 | yes | no | no
RAW_OP_TRUE | anyone-can-spend | - (raw) | no | yes | no
RAW_P2PK | pay-to-public-key | - (raw) | yes | yes | yes
"""
ADDRESS_OP_TRUE = 1
RAW_OP_TRUE = 2
RAW_P2PK = 3
class MiniWallet:
def __init__(self, test_node, *, mode=MiniWalletMode.ADDRESS_OP_TRUE):
self._test_node = test_node
self._utxos = []
self._priv_key = None
self._address = None
assert isinstance(mode, MiniWalletMode)
if mode == MiniWalletMode.RAW_OP_TRUE:
self._scriptPubKey = bytes(CScript([OP_TRUE]))
elif mode == MiniWalletMode.RAW_P2PK:
# use simple deterministic private key (k=1)
self._priv_key = ECKey()
self._priv_key.set((1).to_bytes(32, 'big'), True)
pub_key = self._priv_key.get_pubkey()
self._scriptPubKey = bytes(CScript([pub_key.get_bytes(), OP_CHECKSIG]))
elif mode == MiniWalletMode.ADDRESS_OP_TRUE:
self._address = ADDRESS_BCRT1_P2WSH_OP_TRUE
self._scriptPubKey = hex_str_to_bytes(self._test_node.validateaddress(self._address)['scriptPubKey'])
def scan_blocks(self, *, start=1, num):
"""Scan the blocks for self._address outputs and add them to self._utxos"""
for i in range(start, start + num):
block = self._test_node.getblock(blockhash=self._test_node.getblockhash(i), verbosity=2)
for tx in block['tx']:
self.scan_tx(tx)
def scan_tx(self, tx):
"""Scan the tx for self._scriptPubKey outputs and add them to self._utxos"""
for out in tx['vout']:
if out['scriptPubKey']['hex'] == self._scriptPubKey.hex():
self._utxos.append({'txid': tx['txid'], 'vout': out['n'], 'value': out['value']})
def sign_tx(self, tx, fixed_length=True):
"""Sign tx that has been created by MiniWallet in P2PK mode"""
assert self._priv_key is not None
(sighash, err) = LegacySignatureHash(CScript(self._scriptPubKey), tx, 0, SIGHASH_ALL)
assert err is None
# for exact fee calculation, create only signatures with fixed size by default (>49.89% probability):
# 65 bytes: high-R val (33 bytes) + low-S val (32 bytes)
# with the DER header/skeleton data of 6 bytes added, this leads to a target size of 71 bytes
der_sig = b''
while not len(der_sig) == 71:
der_sig = self._priv_key.sign_ecdsa(sighash)
if not fixed_length:
break
tx.vin[0].scriptSig = CScript([der_sig + bytes(bytearray([SIGHASH_ALL]))])
def generate(self, num_blocks):
"""Generate blocks with coinbase outputs to the internal address, and append the outputs to the internal list"""
blocks = self._test_node.generatetodescriptor(num_blocks, f'raw({self._scriptPubKey.hex()})')
for b in blocks:
cb_tx = self._test_node.getblock(blockhash=b, verbosity=2)['tx'][0]
self._utxos.append({'txid': cb_tx['txid'], 'vout': 0, 'value': cb_tx['vout'][0]['value']})
return blocks
def get_address(self):
return self._address
def get_utxo(self, *, txid: Optional[str]='', mark_as_spent=True):
"""
Returns a utxo and marks it as spent (pops it from the internal list)
Args:
txid: get the first utxo we find from a specific transaction
Note: Can be used to get the change output immediately after a send_self_transfer
"""
index = -1 # by default the last utxo
if txid:
utxo = next(filter(lambda utxo: txid == utxo['txid'], self._utxos))
index = self._utxos.index(utxo)
if mark_as_spent:
return self._utxos.pop(index)
else:
return self._utxos[index]
def send_self_transfer(self, **kwargs):
"""Create and send a tx with the specified fee_rate. Fee may be exact or at most one satoshi higher than needed."""
tx = self.create_self_transfer(**kwargs)
self.sendrawtransaction(from_node=kwargs['from_node'], tx_hex=tx['hex'])
return tx
def create_self_transfer(self, *, fee_rate=Decimal("0.003"), from_node, utxo_to_spend=None, mempool_valid=True, locktime=0, sequence=0):
"""Create and return a tx with the specified fee_rate. Fee may be exact or at most one satoshi higher than needed."""
self._utxos = sorted(self._utxos, key=lambda k: k['value'])
utxo_to_spend = utxo_to_spend or self._utxos.pop() # Pick the largest utxo (if none provided) and hope it covers the fee
if self._priv_key is None:
vsize = Decimal(96) # anyone-can-spend
else:
vsize = Decimal(168) # P2PK (73 bytes scriptSig + 35 bytes scriptPubKey + 60 bytes other)
send_value = satoshi_round(utxo_to_spend['value'] - fee_rate * (vsize / 1000))
fee = utxo_to_spend['value'] - send_value
assert send_value > 0
tx = CTransaction()
tx.vin = [CTxIn(COutPoint(int(utxo_to_spend['txid'], 16), utxo_to_spend['vout']), nSequence=sequence)]
tx.vout = [CTxOut(int(send_value * COIN), self._scriptPubKey)]
tx.nLockTime = locktime
if not self._address:
# raw script
if self._priv_key is not None:
# P2PK, need to sign
self.sign_tx(tx)
else:
# anyone-can-spend
tx.vin[0].scriptSig = CScript([OP_NOP] * 35) # pad to identical size
else:
tx.wit.vtxinwit = [CTxInWitness()]
tx.wit.vtxinwit[0].scriptWitness.stack = [CScript([OP_TRUE])]
tx_hex = tx.serialize().hex()
tx_info = from_node.testmempoolaccept([tx_hex])[0]
assert_equal(mempool_valid, tx_info['allowed'])
if mempool_valid:
assert_equal(tx_info['vsize'], vsize)
assert_equal(tx_info['fees']['base'], fee)
return {'txid': tx_info['txid'], 'wtxid': tx_info['wtxid'], 'hex': tx_hex, 'tx': tx}
def sendrawtransaction(self, *, from_node, tx_hex):
from_node.sendrawtransaction(tx_hex)
self.scan_tx(from_node.decoderawtransaction(tx_hex))
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