1#!/usr/bin/env python3
2# Copyright (c) 2015-2020 The Bitcoin Core developers
3# Distributed under the MIT software license, see the accompanying
4# file COPYING or http://www.opensource.org/licenses/mit-license.php.
5"""Utilities for manipulating blocks and transactions."""
6
7from binascii import a2b_hex
8import struct
9import time
10import unittest
11
12from .address import (
13    key_to_p2sh_p2wpkh,
14    key_to_p2wpkh,
15    script_to_p2sh_p2wsh,
16    script_to_p2wsh,
17)
18from .messages import (
19    CBlock,
20    COIN,
21    COutPoint,
22    CTransaction,
23    CTxIn,
24    CTxInWitness,
25    CTxOut,
26    hash256,
27    hex_str_to_bytes,
28    ser_uint256,
29    tx_from_hex,
30    uint256_from_str,
31)
32from .script import (
33    CScript,
34    CScriptNum,
35    CScriptOp,
36    OP_1,
37    OP_CHECKMULTISIG,
38    OP_CHECKSIG,
39    OP_RETURN,
40    OP_TRUE,
41)
42from .script_util import (
43    key_to_p2wpkh_script,
44    script_to_p2wsh_script,
45)
46from .util import assert_equal
47
48WITNESS_SCALE_FACTOR = 4
49MAX_BLOCK_SIGOPS = 20000
50MAX_BLOCK_SIGOPS_WEIGHT = MAX_BLOCK_SIGOPS * WITNESS_SCALE_FACTOR
51
52# Genesis block time (regtest)
53TIME_GENESIS_BLOCK = 1296688602
54
55# Coinbase transaction outputs can only be spent after this number of new blocks (network rule)
56COINBASE_MATURITY = 100
57
58# From BIP141
59WITNESS_COMMITMENT_HEADER = b"\xaa\x21\xa9\xed"
60
61NORMAL_GBT_REQUEST_PARAMS = {"rules": ["segwit"]}
62
63
64def create_block(hashprev=None, coinbase=None, ntime=None, *, version=None, tmpl=None, txlist=None):
65    """Create a block (with regtest difficulty)."""
66    block = CBlock()
67    if tmpl is None:
68        tmpl = {}
69    block.nVersion = version or tmpl.get('version') or 1
70    block.nTime = ntime or tmpl.get('curtime') or int(time.time() + 600)
71    block.hashPrevBlock = hashprev or int(tmpl['previousblockhash'], 0x10)
72    if tmpl and not tmpl.get('bits') is None:
73        block.nBits = struct.unpack('>I', a2b_hex(tmpl['bits']))[0]
74    else:
75        block.nBits = 0x207fffff  # difficulty retargeting is disabled in REGTEST chainparams
76    if coinbase is None:
77        coinbase = create_coinbase(height=tmpl['height'])
78    block.vtx.append(coinbase)
79    if txlist:
80        for tx in txlist:
81            if not hasattr(tx, 'calc_sha256'):
82                tx = tx_from_hex(tx)
83            block.vtx.append(tx)
84    block.hashMerkleRoot = block.calc_merkle_root()
85    block.calc_sha256()
86    return block
87
88def get_witness_script(witness_root, witness_nonce):
89    witness_commitment = uint256_from_str(hash256(ser_uint256(witness_root) + ser_uint256(witness_nonce)))
90    output_data = WITNESS_COMMITMENT_HEADER + ser_uint256(witness_commitment)
91    return CScript([OP_RETURN, output_data])
92
93def add_witness_commitment(block, nonce=0):
94    """Add a witness commitment to the block's coinbase transaction.
95
96    According to BIP141, blocks with witness rules active must commit to the
97    hash of all in-block transactions including witness."""
98    # First calculate the merkle root of the block's
99    # transactions, with witnesses.
100    witness_nonce = nonce
101    witness_root = block.calc_witness_merkle_root()
102    # witness_nonce should go to coinbase witness.
103    block.vtx[0].wit.vtxinwit = [CTxInWitness()]
104    block.vtx[0].wit.vtxinwit[0].scriptWitness.stack = [ser_uint256(witness_nonce)]
105
106    # witness commitment is the last OP_RETURN output in coinbase
107    block.vtx[0].vout.append(CTxOut(0, get_witness_script(witness_root, witness_nonce)))
108    block.vtx[0].rehash()
109    block.hashMerkleRoot = block.calc_merkle_root()
110    block.rehash()
111
112
113def script_BIP34_coinbase_height(height):
114    if height <= 16:
115        res = CScriptOp.encode_op_n(height)
116        # Append dummy to increase scriptSig size above 2 (see bad-cb-length consensus rule)
117        return CScript([res, OP_1])
118    return CScript([CScriptNum(height)])
119
120
121def create_coinbase(height, pubkey=None, extra_output_script=None, fees=0, nValue=50):
122    """Create a coinbase transaction.
123
124    If pubkey is passed in, the coinbase output will be a P2PK output;
125    otherwise an anyone-can-spend output.
126
127    If extra_output_script is given, make a 0-value output to that
128    script. This is useful to pad block weight/sigops as needed. """
129    coinbase = CTransaction()
130    coinbase.vin.append(CTxIn(COutPoint(0, 0xffffffff), script_BIP34_coinbase_height(height), 0xffffffff))
131    coinbaseoutput = CTxOut()
132    coinbaseoutput.nValue = nValue * COIN
133    if nValue == 50:
134        halvings = int(height / 150)  # regtest
135        coinbaseoutput.nValue >>= halvings
136        coinbaseoutput.nValue += fees
137    if pubkey is not None:
138        coinbaseoutput.scriptPubKey = CScript([pubkey, OP_CHECKSIG])
139    else:
140        coinbaseoutput.scriptPubKey = CScript([OP_TRUE])
141    coinbase.vout = [coinbaseoutput]
142    if extra_output_script is not None:
143        coinbaseoutput2 = CTxOut()
144        coinbaseoutput2.nValue = 0
145        coinbaseoutput2.scriptPubKey = extra_output_script
146        coinbase.vout.append(coinbaseoutput2)
147    coinbase.calc_sha256()
148    return coinbase
149
150def create_tx_with_script(prevtx, n, script_sig=b"", *, amount, script_pub_key=CScript()):
151    """Return one-input, one-output transaction object
152       spending the prevtx's n-th output with the given amount.
153
154       Can optionally pass scriptPubKey and scriptSig, default is anyone-can-spend output.
155    """
156    tx = CTransaction()
157    assert n < len(prevtx.vout)
158    tx.vin.append(CTxIn(COutPoint(prevtx.sha256, n), script_sig, 0xffffffff))
159    tx.vout.append(CTxOut(amount, script_pub_key))
160    tx.calc_sha256()
161    return tx
162
163def create_transaction(node, txid, to_address, *, amount):
164    """ Return signed transaction spending the first output of the
165        input txid. Note that the node must have a wallet that can
166        sign for the output that is being spent.
167    """
168    raw_tx = create_raw_transaction(node, txid, to_address, amount=amount)
169    tx = tx_from_hex(raw_tx)
170    return tx
171
172def create_raw_transaction(node, txid, to_address, *, amount):
173    """ Return raw signed transaction spending the first output of the
174        input txid. Note that the node must have a wallet that can sign
175        for the output that is being spent.
176    """
177    psbt = node.createpsbt(inputs=[{"txid": txid, "vout": 0}], outputs={to_address: amount})
178    for _ in range(2):
179        for w in node.listwallets():
180            wrpc = node.get_wallet_rpc(w)
181            signed_psbt = wrpc.walletprocesspsbt(psbt)
182            psbt = signed_psbt['psbt']
183    final_psbt = node.finalizepsbt(psbt)
184    assert_equal(final_psbt["complete"], True)
185    return final_psbt['hex']
186
187def get_legacy_sigopcount_block(block, accurate=True):
188    count = 0
189    for tx in block.vtx:
190        count += get_legacy_sigopcount_tx(tx, accurate)
191    return count
192
193def get_legacy_sigopcount_tx(tx, accurate=True):
194    count = 0
195    for i in tx.vout:
196        count += i.scriptPubKey.GetSigOpCount(accurate)
197    for j in tx.vin:
198        # scriptSig might be of type bytes, so convert to CScript for the moment
199        count += CScript(j.scriptSig).GetSigOpCount(accurate)
200    return count
201
202def witness_script(use_p2wsh, pubkey):
203    """Create a scriptPubKey for a pay-to-witness TxOut.
204
205    This is either a P2WPKH output for the given pubkey, or a P2WSH output of a
206    1-of-1 multisig for the given pubkey. Returns the hex encoding of the
207    scriptPubKey."""
208    if not use_p2wsh:
209        # P2WPKH instead
210        pkscript = key_to_p2wpkh_script(pubkey)
211    else:
212        # 1-of-1 multisig
213        witness_program = CScript([OP_1, hex_str_to_bytes(pubkey), OP_1, OP_CHECKMULTISIG])
214        pkscript = script_to_p2wsh_script(witness_program)
215    return pkscript.hex()
216
217def create_witness_tx(node, use_p2wsh, utxo, pubkey, encode_p2sh, amount):
218    """Return a transaction (in hex) that spends the given utxo to a segwit output.
219
220    Optionally wrap the segwit output using P2SH."""
221    if use_p2wsh:
222        program = CScript([OP_1, hex_str_to_bytes(pubkey), OP_1, OP_CHECKMULTISIG])
223        addr = script_to_p2sh_p2wsh(program) if encode_p2sh else script_to_p2wsh(program)
224    else:
225        addr = key_to_p2sh_p2wpkh(pubkey) if encode_p2sh else key_to_p2wpkh(pubkey)
226    if not encode_p2sh:
227        assert_equal(node.getaddressinfo(addr)['scriptPubKey'], witness_script(use_p2wsh, pubkey))
228    return node.createrawtransaction([utxo], {addr: amount})
229
230def send_to_witness(use_p2wsh, node, utxo, pubkey, encode_p2sh, amount, sign=True, insert_redeem_script=""):
231    """Create a transaction spending a given utxo to a segwit output.
232
233    The output corresponds to the given pubkey: use_p2wsh determines whether to
234    use P2WPKH or P2WSH; encode_p2sh determines whether to wrap in P2SH.
235    sign=True will have the given node sign the transaction.
236    insert_redeem_script will be added to the scriptSig, if given."""
237    tx_to_witness = create_witness_tx(node, use_p2wsh, utxo, pubkey, encode_p2sh, amount)
238    if (sign):
239        signed = node.signrawtransactionwithwallet(tx_to_witness)
240        assert "errors" not in signed or len(["errors"]) == 0
241        return node.sendrawtransaction(signed["hex"])
242    else:
243        if (insert_redeem_script):
244            tx = tx_from_hex(tx_to_witness)
245            tx.vin[0].scriptSig += CScript([hex_str_to_bytes(insert_redeem_script)])
246            tx_to_witness = tx.serialize().hex()
247
248    return node.sendrawtransaction(tx_to_witness)
249
250class TestFrameworkBlockTools(unittest.TestCase):
251    def test_create_coinbase(self):
252        height = 20
253        coinbase_tx = create_coinbase(height=height)
254        assert_equal(CScriptNum.decode(coinbase_tx.vin[0].scriptSig), height)
255