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Add standard limits for P2WSH with tests 

Github-Pull: #8499
Rebased-From: 3ade2f64cf
This commit is contained in:
Johnson Lau 2016-10-16 23:53:16 +08:00 committed by Wladimir J. van der Laan
parent 9bb2a02f0d
commit 540413d995
4 changed files with 181 additions and 2 deletions
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111
qa/rpc-tests/p2p-segwit.py
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@ -1703,6 +1703,116 @@ class SegWitTest(BitcoinTestFramework):
assert(block_version & (1 << VB_WITNESS_BIT) != 0)
self.nodes[0].setmocktime(0) # undo mocktime
def test_non_standard_witness(self):
print("\tTesting detection of non-standard P2WSH witness")
pad = chr(1).encode('latin-1')
# Create scripts for tests
scripts = []
scripts.append(CScript([OP_DROP] * 100))
scripts.append(CScript([OP_DROP] * 99))
scripts.append(CScript([pad * 59] * 59 + [OP_DROP] * 60))
scripts.append(CScript([pad * 59] * 59 + [OP_DROP] * 61))
p2wsh_scripts = []
assert(len(self.utxo))
tx = CTransaction()
tx.vin.append(CTxIn(COutPoint(self.utxo[0].sha256, self.utxo[0].n), b""))
# For each script, generate a pair of P2WSH and P2SH-P2WSH output.
outputvalue = (self.utxo[0].nValue - 1000) // (len(scripts) * 2)
for i in scripts:
p2wsh = CScript([OP_0, sha256(i)])
p2sh = hash160(p2wsh)
p2wsh_scripts.append(p2wsh)
tx.vout.append(CTxOut(outputvalue, p2wsh))
tx.vout.append(CTxOut(outputvalue, CScript([OP_HASH160, p2sh, OP_EQUAL])))
tx.rehash()
txid = tx.sha256
self.test_node.test_transaction_acceptance(tx, with_witness=False, accepted=True)
self.nodes[0].generate(1)
sync_blocks(self.nodes)
# Creating transactions for tests
p2wsh_txs = []
p2sh_txs = []
for i in range(len(scripts)):
p2wsh_tx = CTransaction()
p2wsh_tx.vin.append(CTxIn(COutPoint(txid,i*2)))
p2wsh_tx.vout.append(CTxOut(outputvalue - 5000, CScript([OP_0, hash160(hex_str_to_bytes(""))])))
p2wsh_tx.wit.vtxinwit.append(CTxInWitness())
p2wsh_tx.rehash()
p2wsh_txs.append(p2wsh_tx)
p2sh_tx = CTransaction()
p2sh_tx.vin.append(CTxIn(COutPoint(txid,i*2+1), CScript([p2wsh_scripts[i]])))
p2sh_tx.vout.append(CTxOut(outputvalue - 5000, CScript([OP_0, hash160(hex_str_to_bytes(""))])))
p2sh_tx.wit.vtxinwit.append(CTxInWitness())
p2sh_tx.rehash()
p2sh_txs.append(p2sh_tx)
# Testing native P2WSH
# Witness stack size, excluding witnessScript, over 100 is non-standard
p2wsh_txs[0].wit.vtxinwit[0].scriptWitness.stack = [pad] * 101 + [scripts[0]]
self.std_node.test_transaction_acceptance(p2wsh_txs[0], True, False, b'bad-witness-nonstandard')
# Non-standard nodes should accept
self.test_node.test_transaction_acceptance(p2wsh_txs[0], True, True)
# Stack element size over 80 bytes is non-standard
p2wsh_txs[1].wit.vtxinwit[0].scriptWitness.stack = [pad * 81] * 100 + [scripts[1]]
# It can't be used to blind a node to the transaction
self.std_node.announce_tx_and_wait_for_getdata(p2wsh_txs[1])
self.std_node.test_transaction_acceptance(p2wsh_txs[1], True, False, b'bad-witness-nonstandard')
self.std_node.announce_tx_and_wait_for_getdata(p2wsh_txs[1])
self.std_node.test_transaction_acceptance(p2wsh_txs[1], True, False, b'bad-witness-nonstandard')
# Non-standard nodes should accept
self.test_node.test_transaction_acceptance(p2wsh_txs[1], True, True)
# Standard nodes should accept if element size is not over 80 bytes
p2wsh_txs[1].wit.vtxinwit[0].scriptWitness.stack = [pad * 80] * 100 + [scripts[1]]
self.std_node.announce_tx_and_wait_for_getdata(p2wsh_txs[1])
self.std_node.test_transaction_acceptance(p2wsh_txs[1], True, True)
# witnessScript size at 3600 bytes is standard
p2wsh_txs[2].wit.vtxinwit[0].scriptWitness.stack = [pad, pad, scripts[2]]
self.test_node.test_transaction_acceptance(p2wsh_txs[2], True, True)
self.std_node.test_transaction_acceptance(p2wsh_txs[2], True, True)
# witnessScript size at 3601 bytes is non-standard
p2wsh_txs[3].wit.vtxinwit[0].scriptWitness.stack = [pad, pad, pad, scripts[3]]
self.std_node.test_transaction_acceptance(p2wsh_txs[3], True, False, b'bad-witness-nonstandard')
# Non-standard nodes should accept
self.test_node.test_transaction_acceptance(p2wsh_txs[3], True, True)
# Repeating the same tests with P2SH-P2WSH
p2sh_txs[0].wit.vtxinwit[0].scriptWitness.stack = [pad] * 101 + [scripts[0]]
self.std_node.test_transaction_acceptance(p2sh_txs[0], True, False, b'bad-witness-nonstandard')
self.test_node.test_transaction_acceptance(p2sh_txs[0], True, True)
p2sh_txs[1].wit.vtxinwit[0].scriptWitness.stack = [pad * 81] * 100 + [scripts[1]]
self.std_node.announce_tx_and_wait_for_getdata(p2sh_txs[1])
self.std_node.test_transaction_acceptance(p2sh_txs[1], True, False, b'bad-witness-nonstandard')
self.std_node.announce_tx_and_wait_for_getdata(p2sh_txs[1])
self.std_node.test_transaction_acceptance(p2sh_txs[1], True, False, b'bad-witness-nonstandard')
self.test_node.test_transaction_acceptance(p2sh_txs[1], True, True)
p2sh_txs[1].wit.vtxinwit[0].scriptWitness.stack = [pad * 80] * 100 + [scripts[1]]
self.std_node.announce_tx_and_wait_for_getdata(p2sh_txs[1])
self.std_node.test_transaction_acceptance(p2sh_txs[1], True, True)
p2sh_txs[2].wit.vtxinwit[0].scriptWitness.stack = [pad, pad, scripts[2]]
self.test_node.test_transaction_acceptance(p2sh_txs[2], True, True)
self.std_node.test_transaction_acceptance(p2sh_txs[2], True, True)
p2sh_txs[3].wit.vtxinwit[0].scriptWitness.stack = [pad, pad, pad, scripts[3]]
self.std_node.test_transaction_acceptance(p2sh_txs[3], True, False, b'bad-witness-nonstandard')
self.test_node.test_transaction_acceptance(p2sh_txs[3], True, True)
self.nodes[0].generate(1) # Mine and clean up the mempool of non-standard node
# Valid but non-standard transactions in a block should be accepted by standard node
sync_blocks(self.nodes)
assert_equal(len(self.nodes[0].getrawmempool()), 0)
assert_equal(len(self.nodes[1].getrawmempool()), 0)
self.utxo.pop(0)
def run_test(self):
# Setup the p2p connections and start up the network thread.
self.test_node = TestNode() # sets NODE_WITNESS|NODE_NETWORK
@ -1775,6 +1885,7 @@ class SegWitTest(BitcoinTestFramework):
self.test_segwit_versions()
self.test_premature_coinbase_witness_spend()
self.test_signature_version_1()
self.test_non_standard_witness()
sync_blocks(self.nodes)
if self.test_upgrade:
self.test_upgrade_after_activation(self.nodes[2], 2)

6
src/main.cpp
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@ -1,5 +1,5 @@
// Copyright (c) 2009-2010 Satoshi Nakamoto
// Copyright (c) 2009-2015 The Bitcoin Core developers
// Copyright (c) 2009-2016 The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
@ -1282,6 +1282,10 @@ bool AcceptToMemoryPoolWorker(CTxMemPool& pool, CValidationState& state, const C
if (fRequireStandard && !AreInputsStandard(tx, view))
return state.Invalid(false, REJECT_NONSTANDARD, "bad-txns-nonstandard-inputs");
// Check for non-standard witness in P2WSH
if (!tx.wit.IsNull() && fRequireStandard && !IsWitnessStandard(tx, view))
return state.DoS(0, false, REJECT_NONSTANDARD, "bad-witness-nonstandard", true);
int64_t nSigOpsCost = GetTransactionSigOpCost(tx, view, STANDARD_SCRIPT_VERIFY_FLAGS);
CAmount nValueOut = tx.GetValueOut();

54
src/policy/policy.cpp
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@ -1,5 +1,5 @@
// Copyright (c) 2009-2010 Satoshi Nakamoto
// Copyright (c) 2009-2015 The Bitcoin developers
// Copyright (c) 2009-2016 The Bitcoin developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
@ -154,6 +154,58 @@ bool AreInputsStandard(const CTransaction& tx, const CCoinsViewCache& mapInputs)
return true;
}
bool IsWitnessStandard(const CTransaction& tx, const CCoinsViewCache& mapInputs)
{
if (tx.IsCoinBase())
return true; // Coinbases are skipped
for (unsigned int i = 0; i < tx.vin.size(); i++)
{
// We don't care if witness for this input is empty, since it must not be bloated.
// If the script is invalid without witness, it would be caught sooner or later during validation.
if (tx.wit.vtxinwit[i].IsNull())
continue;
const CTxOut &prev = mapInputs.GetOutputFor(tx.vin[i]);
// get the scriptPubKey corresponding to this input:
CScript prevScript = prev.scriptPubKey;
if (prevScript.IsPayToScriptHash()) {
std::vector <std::vector<unsigned char> > stack;
// If the scriptPubKey is P2SH, we try to extract the redeemScript casually by converting the scriptSig
// into a stack. We do not check IsPushOnly nor compare the hash as these will be done later anyway.
// If the check fails at this stage, we know that this txid must be a bad one.
if (!EvalScript(stack, tx.vin[i].scriptSig, SCRIPT_VERIFY_NONE, BaseSignatureChecker(), SIGVERSION_BASE))
return false;
if (stack.empty())
return false;
prevScript = CScript(stack.back().begin(), stack.back().end());
}
int witnessversion = 0;
std::vector<unsigned char> witnessprogram;
// Non-witness program must not be associated with any witness
if (!prevScript.IsWitnessProgram(witnessversion, witnessprogram))
return false;
// Check P2WSH standard limits
if (witnessversion == 0 && witnessprogram.size() == 32) {
if (tx.wit.vtxinwit[i].scriptWitness.stack.back().size() > MAX_STANDARD_P2WSH_SCRIPT_SIZE)
return false;
size_t sizeWitnessStack = tx.wit.vtxinwit[i].scriptWitness.stack.size() - 1;
if (sizeWitnessStack > MAX_STANDARD_P2WSH_STACK_ITEMS)
return false;
for (unsigned int j = 0; j < sizeWitnessStack; j++) {
if (tx.wit.vtxinwit[i].scriptWitness.stack[j].size() > MAX_STANDARD_P2WSH_STACK_ITEM_SIZE)
return false;
}
}
}
return true;
}
unsigned int nBytesPerSigOp = DEFAULT_BYTES_PER_SIGOP;
int64_t GetVirtualTransactionSize(int64_t nWeight, int64_t nSigOpCost)

12
src/policy/policy.h
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@ -30,6 +30,12 @@ static const unsigned int MAX_STANDARD_TX_SIGOPS_COST = MAX_BLOCK_SIGOPS_COST/5;
static const unsigned int DEFAULT_MAX_MEMPOOL_SIZE = 300;
/** Default for -bytespersigop */
static const unsigned int DEFAULT_BYTES_PER_SIGOP = 20;
/** The maximum number of witness stack items in a standard P2WSH script */
static const unsigned int MAX_STANDARD_P2WSH_STACK_ITEMS = 100;
/** The maximum size of each witness stack item in a standard P2WSH script */
static const unsigned int MAX_STANDARD_P2WSH_STACK_ITEM_SIZE = 80;
/** The maximum size of a standard witnessScript */
static const unsigned int MAX_STANDARD_P2WSH_SCRIPT_SIZE = 3600;
/**
* Standard script verification flags that standard transactions will comply
* with. However scripts violating these flags may still be present in valid
@ -69,6 +75,12 @@ bool IsStandardTx(const CTransaction& tx, std::string& reason, const bool witnes
* @return True if all inputs (scriptSigs) use only standard transaction forms
*/
bool AreInputsStandard(const CTransaction& tx, const CCoinsViewCache& mapInputs);
/**
* Check if the transaction is over standard P2WSH resources limit:
* 3600bytes witnessScript size, 80bytes per witness stack element, 100 witness stack elements
* These limits are adequate for multi-signature up to n-of-100 using OP_CHECKSIG, OP_ADD, and OP_EQUAL,
*/
bool IsWitnessStandard(const CTransaction& tx, const CCoinsViewCache& mapInputs);
extern unsigned int nBytesPerSigOp;