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[REFACTOR] Abstract out script execution out of VerifyWitnessProgram()

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This removes the unclear reliance on "falling through" to get to the
script execution part.

Also fix some code style issues.
This commit is contained in:
Pieter Wuille 2019-10-06 12:13:20 -07:00
parent 2bdc476d4d
commit c8e24ddce3
1 changed files with 25 additions and 23 deletions
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48
src/script/interpreter.cpp
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@ -1414,9 +1414,26 @@ bool GenericTransactionSignatureChecker<T>::CheckSequence(const CScriptNum& nSeq
template class GenericTransactionSignatureChecker<CTransaction>;
template class GenericTransactionSignatureChecker<CMutableTransaction>;
static bool ExecuteWitnessScript(std::vector<valtype>::const_iterator begin, std::vector<valtype>::const_iterator end, const CScript& scriptPubKey, unsigned int flags, SigVersion sigversion, const BaseSignatureChecker& checker, ScriptError* serror)
{
std::vector<valtype> stack{begin, end};
// Disallow stack item size > MAX_SCRIPT_ELEMENT_SIZE in witness stack
for (const valtype& elem : stack) {
if (elem.size() > MAX_SCRIPT_ELEMENT_SIZE) return set_error(serror, SCRIPT_ERR_PUSH_SIZE);
}
// Run the script interpreter.
if (!EvalScript(stack, scriptPubKey, flags, checker, sigversion, 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;
}
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) {
@ -1426,45 +1443,30 @@ static bool VerifyWitnessProgram(const CScriptWitness& witness, int witversion,
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);
}
return ExecuteWitnessScript(witness.stack.begin(), witness.stack.end() - 1, scriptPubKey, flags, SigVersion::WITNESS_V0, checker, serror);
} 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;
return ExecuteWitnessScript(witness.stack.begin(), witness.stack.end(), scriptPubKey, flags, SigVersion::WITNESS_V0, checker, serror);
} 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 {
if (flags & SCRIPT_VERIFY_DISCOURAGE_UPGRADABLE_WITNESS_PROGRAM) {
return set_error(serror, SCRIPT_ERR_DISCOURAGE_UPGRADABLE_WITNESS_PROGRAM);
}
// Higher version witness scripts return true for future softfork compatibility
return set_success(serror);
return true;
}
// 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;
// There is intentionally no return statement here, to be able to use "control reaches end of non-void function" warnings to detect gaps in the logic above.
}
bool VerifyScript(const CScript& scriptSig, const CScript& scriptPubKey, const CScriptWitness* witness, unsigned int flags, const BaseSignatureChecker& checker, ScriptError* serror)