Function VerifyWitnessProgram

src/script/interpreter.cpp:1462–1513

template class GenericTransactionSignatureChecker<CMutableTransaction>;

static bool VerifyWitnessProgram(const CScriptWitness& witness, int witversion, const std::vector<unsigned char>& program, unsigned int flags, const BaseSignatureChecker& checker, ScriptError* serror)
{
    std::vector<std::vector<unsigned char> > stack;
    CScript scriptPubKey;

    if (witversion == 0) {
        if (program.size() == WITNESS_V0_SCRIPTHASH_SIZE) {
            // Version 0 segregated witness program: SHA256(CScript) inside the program, CScript + inputs in witness
            if (witness.stack.size() == 0) {
                return set_error(serror, SCRIPT_ERR_WITNESS_PROGRAM_WITNESS_EMPTY);
            }
            scriptPubKey = CScript(witness.stack.back().begin(), witness.stack.back().end());
            stack = std::vector<std::vector<unsigned char> >(witness.stack.begin(), witness.stack.end() - 1);
            uint256 hashScriptPubKey;
            CSHA256().Write(&scriptPubKey[0], scriptPubKey.size()).Finalize(hashScriptPubKey.begin());
            if (memcmp(hashScriptPubKey.begin(), program.data(), 32)) {
                return set_error(serror, SCRIPT_ERR_WITNESS_PROGRAM_MISMATCH);
            }
        } else if (program.size() == WITNESS_V0_KEYHASH_SIZE) {
            // Special case for pay-to-pubkeyhash; signature + pubkey in witness
            if (witness.stack.size() != 2) {
                return set_error(serror, SCRIPT_ERR_WITNESS_PROGRAM_MISMATCH); // 2 items in witness
            }
            scriptPubKey << OP_DUP << OP_HASH160 << program << OP_EQUALVERIFY << OP_CHECKSIG;
            stack = witness.stack;
        } else {
            return set_error(serror, SCRIPT_ERR_WITNESS_PROGRAM_WRONG_LENGTH);
        }
    } else if (flags & SCRIPT_VERIFY_DISCOURAGE_UPGRADABLE_WITNESS_PROGRAM) {
        return set_error(serror, SCRIPT_ERR_DISCOURAGE_UPGRADABLE_WITNESS_PROGRAM);
    } else {
        // Higher version witness scripts return true for future softfork compatibility
        return set_success(serror);
    }

    // Disallow stack item size > MAX_SCRIPT_ELEMENT_SIZE in witness stack
    for (unsigned int i = 0; i < stack.size(); i++) {
        if (stack.at(i).size() > MAX_SCRIPT_ELEMENT_SIZE)
            return set_error(serror, SCRIPT_ERR_PUSH_SIZE);
    }

    if (!EvalScript(stack, scriptPubKey, flags, checker, SigVersion::WITNESS_V0, serror)) {
        return false;
    }

    // Scripts inside witness implicitly require cleanstack behaviour
    if (stack.size() != 1)
        return set_error(serror, SCRIPT_ERR_CLEANSTACK);
    if (!CastToBool(stack.back()))
        return set_error(serror, SCRIPT_ERR_EVAL_FALSE);
    return true;
}

bool VerifyScript(const CScript& scriptSig, const CScript& scriptPubKey, const CScriptWitness* witness, unsigned int flags, const BaseSignatureChecker& checker, ScriptError* serror)
{