Function ValidateInputsStandardness

src/policy/policy.cpp:214–263

* Check transaction inputs. * * This does three things: * * Prevents mempool acceptance of spends of future * segwit versions we don't know how to validate * * Mitigates a potential denial-of-service attack with * P2SH scripts with a crazy number of expensive * CHECKSIG/CHECKMULTISIG operations. * * Prevents spends of unknown/irregular scriptPubKeys, * which mitigates poten

 * We also check the total number of non-witness sigops across the whole transaction, as per BIP54.
 */
TxValidationState ValidateInputsStandardness(const CTransaction& tx, const CCoinsViewCache& mapInputs)
{
    TxValidationState state;
    if (tx.IsCoinBase()) {
        return state; // Coinbases don't use vin normally
    }

    if (!CheckSigopsBIP54(tx, mapInputs)) {
        state.Invalid(TxValidationResult::TX_INPUTS_NOT_STANDARD, "bad-txns-nonstandard-inputs", "non-witness sigops exceed bip54 limit");
        return state;
    }

    for (unsigned int i = 0; i < tx.vin.size(); i++) {
        const CTxOut& prev = mapInputs.AccessCoin(tx.vin[i].prevout).out;

        std::vector<std::vector<unsigned char> > vSolutions;
        TxoutType whichType = Solver(prev.scriptPubKey, vSolutions);
        if (whichType == TxoutType::NONSTANDARD) {
            state.Invalid(TxValidationResult::TX_INPUTS_NOT_STANDARD, "bad-txns-nonstandard-inputs", strprintf("input %u script unknown", i));
            return state;
        } else if (whichType == TxoutType::WITNESS_UNKNOWN) {
            // WITNESS_UNKNOWN failures are typically also caught with a policy
            // flag in the script interpreter, but it can be helpful to catch
            // this type of NONSTANDARD transaction earlier in transaction
            // validation.
            state.Invalid(TxValidationResult::TX_INPUTS_NOT_STANDARD, "bad-txns-nonstandard-inputs", strprintf("input %u witness program is undefined", i));
            return state;
        } else if (whichType == TxoutType::SCRIPTHASH) {
            std::vector<std::vector<unsigned char> > stack;
            ScriptError serror;
            // convert the scriptSig into a stack, so we can inspect the redeemScript
            if (!EvalScript(stack, tx.vin[i].scriptSig, SCRIPT_VERIFY_NONE, BaseSignatureChecker(), SigVersion::BASE, &serror)) {
                state.Invalid(TxValidationResult::TX_INPUTS_NOT_STANDARD, "bad-txns-nonstandard-inputs", strprintf("p2sh scriptsig malformed (input %u: %s)", i, ScriptErrorString(serror)));
                return state;
            }
            if (stack.empty()) {
                state.Invalid(TxValidationResult::TX_INPUTS_NOT_STANDARD, "bad-txns-nonstandard-inputs", strprintf("input %u P2SH redeemscript missing", i));
                return state;
            }
            CScript subscript(stack.back().begin(), stack.back().end());
            unsigned int sigop_count = subscript.GetSigOpCount(true);
            if (sigop_count > MAX_P2SH_SIGOPS) {
                state.Invalid(TxValidationResult::TX_INPUTS_NOT_STANDARD, "bad-txns-nonstandard-inputs", strprintf("p2sh redeemscript sigops exceed limit (input %u: %u > %u)", i, sigop_count, MAX_P2SH_SIGOPS));
                return state;
            }
        }
    }

    return state;
}

bool IsWitnessStandard(const CTransaction& tx, const CCoinsViewCache& mapInputs)
{