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#!/usr/bin/env python3
# Copyright (c) 2015-2021 The Bitcoin Core developers
# Distributed under the MIT software license, see the accompanying
# file COPYING or http://www.opensource.org/licenses/mit-license.php.
"""Utilities for manipulating blocks and transactions."""
import struct
import time
import unittest
from .address import (
key_to_p2sh_p2wpkh,
key_to_p2wpkh,
script_to_p2sh_p2wsh,
script_to_p2wsh,
)
from .messages import (
CBlock,
COIN,
COutPoint,
CTransaction,
CTxIn,
CTxInWitness,
CTxOut,
SEQUENCE_FINAL,
hash256,
ser_uint256,
tx_from_hex,
uint256_from_str,
)
from .script import (
CScript,
CScriptNum,
CScriptOp,
OP_1,
OP_RETURN,
OP_TRUE,
)
from .script_util import (
key_to_p2pk_script,
key_to_p2wpkh_script,
keys_to_multisig_script,
script_to_p2wsh_script,
)
from .util import assert_equal
WITNESS_SCALE_FACTOR = 4
MAX_BLOCK_SIGOPS = 20000
MAX_BLOCK_SIGOPS_WEIGHT = MAX_BLOCK_SIGOPS * WITNESS_SCALE_FACTOR
# Genesis block time (regtest)
TIME_GENESIS_BLOCK = 1296688602
MAX_FUTURE_BLOCK_TIME = 2 * 60 * 60
# Coinbase transaction outputs can only be spent after this number of new blocks (network rule)
COINBASE_MATURITY = 100
# From BIP141
WITNESS_COMMITMENT_HEADER = b"\xaa\x21\xa9\xed"
NORMAL_GBT_REQUEST_PARAMS = {"rules": ["segwit"]}
VERSIONBITS_LAST_OLD_BLOCK_VERSION = 4
MIN_BLOCKS_TO_KEEP = 288
def create_block(hashprev=None, coinbase=None, ntime=None, *, version=None, tmpl=None, txlist=None):
"""Create a block (with regtest difficulty)."""
block = CBlock()
if tmpl is None:
tmpl = {}
block.nVersion = version or tmpl.get('version') or VERSIONBITS_LAST_OLD_BLOCK_VERSION
block.nTime = ntime or tmpl.get('curtime') or int(time.time() + 600)
block.hashPrevBlock = hashprev or int(tmpl['previousblockhash'], 0x10)
if tmpl and not tmpl.get('bits') is None:
block.nBits = struct.unpack('>I', bytes.fromhex(tmpl['bits']))[0]
else:
block.nBits = 0x207fffff # difficulty retargeting is disabled in REGTEST chainparams
if coinbase is None:
coinbase = create_coinbase(height=tmpl['height'])
block.vtx.append(coinbase)
if txlist:
for tx in txlist:
if not hasattr(tx, 'calc_sha256'):
tx = tx_from_hex(tx)
block.vtx.append(tx)
block.hashMerkleRoot = block.calc_merkle_root()
block.calc_sha256()
return block
def get_witness_script(witness_root, witness_nonce):
witness_commitment = uint256_from_str(hash256(ser_uint256(witness_root) + ser_uint256(witness_nonce)))
output_data = WITNESS_COMMITMENT_HEADER + ser_uint256(witness_commitment)
return CScript([OP_RETURN, output_data])
def add_witness_commitment(block, nonce=0):
"""Add a witness commitment to the block's coinbase transaction.
According to BIP141, blocks with witness rules active must commit to the
hash of all in-block transactions including witness."""
# First calculate the merkle root of the block's
# transactions, with witnesses.
witness_nonce = nonce
witness_root = block.calc_witness_merkle_root()
# witness_nonce should go to coinbase witness.
block.vtx[0].wit.vtxinwit = [CTxInWitness()]
block.vtx[0].wit.vtxinwit[0].scriptWitness.stack = [ser_uint256(witness_nonce)]
# witness commitment is the last OP_RETURN output in coinbase
block.vtx[0].vout.append(CTxOut(0, get_witness_script(witness_root, witness_nonce)))
block.vtx[0].rehash()
block.hashMerkleRoot = block.calc_merkle_root()
block.rehash()
def script_BIP34_coinbase_height(height):
if height <= 16:
res = CScriptOp.encode_op_n(height)
# Append dummy to increase scriptSig size above 2 (see bad-cb-length consensus rule)
return CScript([res, OP_1])
return CScript([CScriptNum(height)])
def create_coinbase(height, pubkey=None, *, script_pubkey=None, extra_output_script=None, fees=0, nValue=50):
"""Create a coinbase transaction.
If pubkey is passed in, the coinbase output will be a P2PK output;
otherwise an anyone-can-spend output.
If extra_output_script is given, make a 0-value output to that
script. This is useful to pad block weight/sigops as needed. """
coinbase = CTransaction()
coinbase.vin.append(CTxIn(COutPoint(0, 0xffffffff), script_BIP34_coinbase_height(height), SEQUENCE_FINAL))
coinbaseoutput = CTxOut()
coinbaseoutput.nValue = nValue * COIN
if nValue == 50:
halvings = int(height / 150) # regtest
coinbaseoutput.nValue >>= halvings
coinbaseoutput.nValue += fees
if pubkey is not None:
coinbaseoutput.scriptPubKey = key_to_p2pk_script(pubkey)
elif script_pubkey is not None:
coinbaseoutput.scriptPubKey = script_pubkey
else:
coinbaseoutput.scriptPubKey = CScript([OP_TRUE])
coinbase.vout = [coinbaseoutput]
if extra_output_script is not None:
coinbaseoutput2 = CTxOut()
coinbaseoutput2.nValue = 0
coinbaseoutput2.scriptPubKey = extra_output_script
coinbase.vout.append(coinbaseoutput2)
coinbase.calc_sha256()
return coinbase
def create_tx_with_script(prevtx, n, script_sig=b"", *, amount, script_pub_key=CScript()):
"""Return one-input, one-output transaction object
spending the prevtx's n-th output with the given amount.
Can optionally pass scriptPubKey and scriptSig, default is anyone-can-spend output.
"""
tx = CTransaction()
assert n < len(prevtx.vout)
tx.vin.append(CTxIn(COutPoint(prevtx.sha256, n), script_sig, SEQUENCE_FINAL))
tx.vout.append(CTxOut(amount, script_pub_key))
tx.calc_sha256()
return tx
def get_legacy_sigopcount_block(block, accurate=True):
count = 0
for tx in block.vtx:
count += get_legacy_sigopcount_tx(tx, accurate)
return count
def get_legacy_sigopcount_tx(tx, accurate=True):
count = 0
for i in tx.vout:
count += i.scriptPubKey.GetSigOpCount(accurate)
for j in tx.vin:
# scriptSig might be of type bytes, so convert to CScript for the moment
count += CScript(j.scriptSig).GetSigOpCount(accurate)
return count
def witness_script(use_p2wsh, pubkey):
"""Create a scriptPubKey for a pay-to-witness TxOut.
This is either a P2WPKH output for the given pubkey, or a P2WSH output of a
1-of-1 multisig for the given pubkey. Returns the hex encoding of the
scriptPubKey."""
if not use_p2wsh:
# P2WPKH instead
pkscript = key_to_p2wpkh_script(pubkey)
else:
# 1-of-1 multisig
witness_script = keys_to_multisig_script([pubkey])
pkscript = script_to_p2wsh_script(witness_script)
return pkscript.hex()
def create_witness_tx(node, use_p2wsh, utxo, pubkey, encode_p2sh, amount):
"""Return a transaction (in hex) that spends the given utxo to a segwit output.
Optionally wrap the segwit output using P2SH."""
if use_p2wsh:
program = keys_to_multisig_script([pubkey])
addr = script_to_p2sh_p2wsh(program) if encode_p2sh else script_to_p2wsh(program)
else:
addr = key_to_p2sh_p2wpkh(pubkey) if encode_p2sh else key_to_p2wpkh(pubkey)
if not encode_p2sh:
assert_equal(node.getaddressinfo(addr)['scriptPubKey'], witness_script(use_p2wsh, pubkey))
return node.createrawtransaction([utxo], {addr: amount})
def send_to_witness(use_p2wsh, node, utxo, pubkey, encode_p2sh, amount, sign=True, insert_redeem_script=""):
"""Create a transaction spending a given utxo to a segwit output.
The output corresponds to the given pubkey: use_p2wsh determines whether to
use P2WPKH or P2WSH; encode_p2sh determines whether to wrap in P2SH.
sign=True will have the given node sign the transaction.
insert_redeem_script will be added to the scriptSig, if given."""
tx_to_witness = create_witness_tx(node, use_p2wsh, utxo, pubkey, encode_p2sh, amount)
if (sign):
signed = node.signrawtransactionwithwallet(tx_to_witness)
assert "errors" not in signed or len(["errors"]) == 0
return node.sendrawtransaction(signed["hex"])
else:
if (insert_redeem_script):
tx = tx_from_hex(tx_to_witness)
tx.vin[0].scriptSig += CScript([bytes.fromhex(insert_redeem_script)])
tx_to_witness = tx.serialize().hex()
return node.sendrawtransaction(tx_to_witness)
class TestFrameworkBlockTools(unittest.TestCase):
def test_create_coinbase(self):
height = 20
coinbase_tx = create_coinbase(height=height)
assert_equal(CScriptNum.decode(coinbase_tx.vin[0].scriptSig), height)
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