bool IsStandardTx(const CTransaction& tx, std::string& reason)
{
if (tx.nVersion > CTransaction::CURRENT_VERSION || tx.nVersion < 1) {
reason = "version";
return false;
}
// Extremely large transactions with lots of inputs can cost the network
// almost as much to process as they cost the sender in fees, because
// computing signature hashes is O(ninputs*txsize). Limiting transactions
// to MAX_STANDARD_TX_SIZE mitigates CPU exhaustion attacks.
unsigned int sz = tx.GetSerializeSize(SER_NETWORK, CTransaction::CURRENT_VERSION);
if (sz >= MAX_STANDARD_TX_SIZE) {
reason = "tx-size";
return false;
}
BOOST_FOREACH(const CTxIn& txin, tx.vin)
{
// Biggest 'standard' txin is a 15-of-15 P2SH multisig with compressed
// keys. (remember the 520 byte limit on redeemScript size) That works
// out to a (15*(33+1))+3=513 byte redeemScript, 513+1+15*(73+1)+3=1627
// bytes of scriptSig, which we round off to 1650 bytes for some minor
// future-proofing. That's also enough to spend a 20-of-20
// CHECKMULTISIG scriptPubKey, though such a scriptPubKey is not
// considered standard)
if (txin.scriptSig.size() > 1650) {
reason = "scriptsig-size";
return false;
}
if (!txin.scriptSig.IsPushOnly()) {
reason = "scriptsig-not-pushonly";
return false;
}
}
unsigned int nDataOut = 0;
txnouttype whichType;
BOOST_FOREACH(const CTxOut& txout, tx.vout) {
if (!::IsStandard(txout.scriptPubKey, whichType)) {
reason = "scriptpubkey";
return false;
}
if (whichType == TX_NULL_DATA)
nDataOut++;
else if ((whichType == TX_MULTISIG) && (!fIsBareMultisigStd)) {
reason = "bare-multisig";
return false;
} else if (txout.IsDust(::minRelayTxFee)) {
reason = "dust";
return false;
}
}
// only one OP_RETURN txout is permitted
if (nDataOut > 1) {
reason = "multi-op-return";
return false;
}
return true;
}
