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Merge bitcoin/bitcoin#29777: test: refactor: introduce and use calculate_input_weight helper

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6d91cb781c test: add unit tests for `calculate_input_weight` (Sebastian Falbesoner)
f81fad5e0f test: introduce and use `calculate_input_weight` helper (Sebastian Falbesoner)

Pull request description:

  Rather than manually estimating an input's weight by adding up all the involved components (fixed-size skeleton, compact-serialized lengths, and the actual scriptSig / witness stack items) we can simply take use of the serialization classes `CTxIn` / `CTxInWitness` instead, to achieve the same with significantly less code.

  The new helper is used in the functional tests rpc_psbt.py and wallet_send.py, where the previous manual estimation code was
  duplicated. Unit tests are added in the second commit.

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Ava Chow 2024-04-22 18:45:39 -04:00
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4 changed files with 70 additions and 29 deletions
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17
test/functional/rpc_psbt.py
View file

@ -16,8 +16,6 @@ from test_framework.messages import (
CTxIn,
CTxOut,
MAX_BIP125_RBF_SEQUENCE,
WITNESS_SCALE_FACTOR,
ser_compact_size,
)
from test_framework.psbt import (
PSBT,
@ -42,6 +40,7 @@ from test_framework.util import (
find_vout_for_address,
)
from test_framework.wallet_util import (
calculate_input_weight,
generate_keypair,
get_generate_key,
)
@ -752,17 +751,9 @@ class PSBTTest(BitcoinTestFramework):
input_idx = i
break
psbt_in = dec["inputs"][input_idx]
# Calculate the input weight
# (prevout + sequence + length of scriptSig + scriptsig) * WITNESS_SCALE_FACTOR + len of num scriptWitness stack items + (length of stack item + stack item) * N stack items
# Note that occasionally this weight estimate may be slightly larger or smaller than the real weight
# as sometimes ECDSA signatures are one byte shorter than expected with a probability of 1/128
len_scriptsig = len(psbt_in["final_scriptSig"]["hex"]) // 2 if "final_scriptSig" in psbt_in else 0
len_scriptsig += len(ser_compact_size(len_scriptsig))
len_scriptwitness = (sum([(len(x) // 2) + len(ser_compact_size(len(x) // 2)) for x in psbt_in["final_scriptwitness"]]) + len(ser_compact_size(len(psbt_in["final_scriptwitness"])))) if "final_scriptwitness" in psbt_in else 0
len_prevout_txid = 32
len_prevout_index = 4
len_sequence = 4
input_weight = ((len_prevout_txid + len_prevout_index + len_sequence + len_scriptsig) * WITNESS_SCALE_FACTOR) + len_scriptwitness
scriptsig_hex = psbt_in["final_scriptSig"]["hex"] if "final_scriptSig" in psbt_in else ""
witness_stack_hex = psbt_in["final_scriptwitness"] if "final_scriptwitness" in psbt_in else None
input_weight = calculate_input_weight(scriptsig_hex, witness_stack_hex)
low_input_weight = input_weight // 2
high_input_weight = input_weight * 2

58
test/functional/test_framework/wallet_util.py
View file

@ -4,6 +4,7 @@
# file COPYING or http://www.opensource.org/licenses/mit-license.php.
"""Useful util functions for testing the wallet"""
from collections import namedtuple
import unittest
from test_framework.address import (
byte_to_base58,
@ -15,6 +16,11 @@ from test_framework.address import (
script_to_p2wsh,
)
from test_framework.key import ECKey
from test_framework.messages import (
CTxIn,
CTxInWitness,
WITNESS_SCALE_FACTOR,
)
from test_framework.script_util import (
key_to_p2pkh_script,
key_to_p2wpkh_script,
@ -123,6 +129,19 @@ def generate_keypair(compressed=True, wif=False):
privkey = bytes_to_wif(privkey.get_bytes(), compressed)
return privkey, pubkey
def calculate_input_weight(scriptsig_hex, witness_stack_hex=None):
"""Given a scriptSig and a list of witness stack items for an input in hex format,
calculate the total input weight. If the input has no witness data,
`witness_stack_hex` can be set to None."""
tx_in = CTxIn(scriptSig=bytes.fromhex(scriptsig_hex))
witness_size = 0
if witness_stack_hex is not None:
tx_inwit = CTxInWitness()
for witness_item_hex in witness_stack_hex:
tx_inwit.scriptWitness.stack.append(bytes.fromhex(witness_item_hex))
witness_size = len(tx_inwit.serialize())
return len(tx_in.serialize()) * WITNESS_SCALE_FACTOR + witness_size
class WalletUnlock():
"""
A context manager for unlocking a wallet with a passphrase and automatically locking it afterward.
@ -141,3 +160,42 @@ class WalletUnlock():
def __exit__(self, *args):
_ = args
self.wallet.walletlock()
class TestFrameworkWalletUtil(unittest.TestCase):
def test_calculate_input_weight(self):
SKELETON_BYTES = 32 + 4 + 4 # prevout-txid, prevout-index, sequence
SMALL_LEN_BYTES = 1 # bytes needed for encoding scriptSig / witness item lenghts < 253
LARGE_LEN_BYTES = 3 # bytes needed for encoding scriptSig / witness item lengths >= 253
# empty scriptSig, no witness
self.assertEqual(calculate_input_weight(""),
(SKELETON_BYTES + SMALL_LEN_BYTES) * WITNESS_SCALE_FACTOR)
self.assertEqual(calculate_input_weight("", None),
(SKELETON_BYTES + SMALL_LEN_BYTES) * WITNESS_SCALE_FACTOR)
# small scriptSig, no witness
scriptSig_small = "00"*252
self.assertEqual(calculate_input_weight(scriptSig_small, None),
(SKELETON_BYTES + SMALL_LEN_BYTES + 252) * WITNESS_SCALE_FACTOR)
# small scriptSig, empty witness stack
self.assertEqual(calculate_input_weight(scriptSig_small, []),
(SKELETON_BYTES + SMALL_LEN_BYTES + 252) * WITNESS_SCALE_FACTOR + SMALL_LEN_BYTES)
# large scriptSig, no witness
scriptSig_large = "00"*253
self.assertEqual(calculate_input_weight(scriptSig_large, None),
(SKELETON_BYTES + LARGE_LEN_BYTES + 253) * WITNESS_SCALE_FACTOR)
# large scriptSig, empty witness stack
self.assertEqual(calculate_input_weight(scriptSig_large, []),
(SKELETON_BYTES + LARGE_LEN_BYTES + 253) * WITNESS_SCALE_FACTOR + SMALL_LEN_BYTES)
# empty scriptSig, 5 small witness stack items
self.assertEqual(calculate_input_weight("", ["00", "11", "22", "33", "44"]),
((SKELETON_BYTES + SMALL_LEN_BYTES) * WITNESS_SCALE_FACTOR) + SMALL_LEN_BYTES + 5 * SMALL_LEN_BYTES + 5)
# empty scriptSig, 253 small witness stack items
self.assertEqual(calculate_input_weight("", ["00"]*253),
((SKELETON_BYTES + SMALL_LEN_BYTES) * WITNESS_SCALE_FACTOR) + LARGE_LEN_BYTES + 253 * SMALL_LEN_BYTES + 253)
# small scriptSig, 3 large witness stack items
self.assertEqual(calculate_input_weight(scriptSig_small, ["00"*253]*3),
((SKELETON_BYTES + SMALL_LEN_BYTES + 252) * WITNESS_SCALE_FACTOR) + SMALL_LEN_BYTES + 3 * LARGE_LEN_BYTES + 3*253)
# large scriptSig, 3 large witness stack items
self.assertEqual(calculate_input_weight(scriptSig_large, ["00"*253]*3),
((SKELETON_BYTES + LARGE_LEN_BYTES + 253) * WITNESS_SCALE_FACTOR) + SMALL_LEN_BYTES + 3 * LARGE_LEN_BYTES + 3*253)

1
test/functional/test_runner.py
View file

@ -85,6 +85,7 @@ TEST_FRAMEWORK_MODULES = [
"crypto.ripemd160",
"script",
"segwit_addr",
"wallet_util",
]
EXTENDED_SCRIPTS = [

23
test/functional/wallet_send.py
View file

@ -9,10 +9,6 @@ from itertools import product
from test_framework.authproxy import JSONRPCException
from test_framework.descriptors import descsum_create
from test_framework.messages import (
ser_compact_size,
WITNESS_SCALE_FACTOR,
)
from test_framework.test_framework import BitcoinTestFramework
from test_framework.util import (
assert_equal,
@ -21,7 +17,10 @@ from test_framework.util import (
assert_raises_rpc_error,
count_bytes,
)
from test_framework.wallet_util import generate_keypair
from test_framework.wallet_util import (
calculate_input_weight,
generate_keypair,
)
class WalletSendTest(BitcoinTestFramework):
@ -543,17 +542,9 @@ class WalletSendTest(BitcoinTestFramework):
input_idx = i
break
psbt_in = dec["inputs"][input_idx]
# Calculate the input weight
# (prevout + sequence + length of scriptSig + scriptsig) * WITNESS_SCALE_FACTOR + len of num scriptWitness stack items + (length of stack item + stack item) * N stack items
# Note that occasionally this weight estimate may be slightly larger or smaller than the real weight
# as sometimes ECDSA signatures are one byte shorter than expected with a probability of 1/128
len_scriptsig = len(psbt_in["final_scriptSig"]["hex"]) // 2 if "final_scriptSig" in psbt_in else 0
len_scriptsig += len(ser_compact_size(len_scriptsig))
len_scriptwitness = (sum([(len(x) // 2) + len(ser_compact_size(len(x) // 2)) for x in psbt_in["final_scriptwitness"]]) + len(ser_compact_size(len(psbt_in["final_scriptwitness"])))) if "final_scriptwitness" in psbt_in else 0
len_prevout_txid = 32
len_prevout_index = 4
len_sequence = 4
input_weight = ((len_prevout_txid + len_prevout_index + len_sequence + len_scriptsig) * WITNESS_SCALE_FACTOR) + len_scriptwitness
scriptsig_hex = psbt_in["final_scriptSig"]["hex"] if "final_scriptSig" in psbt_in else ""
witness_stack_hex = psbt_in["final_scriptwitness"] if "final_scriptwitness" in psbt_in else None
input_weight = calculate_input_weight(scriptsig_hex, witness_stack_hex)
# Input weight error conditions
assert_raises_rpc_error(