fix(wallet): opreturn_burn return change + widen txfee to CAmount

#10 (HIGH) opreturn_burn selected UTXOs for nAmount+txfee but pushed only the
burn vout and returned - so the entire selected-input surplus was silently paid
as miner fee (e.g. a 500-coin UTXO burning 10 lost ~490). Push a change output
for (inputs - nAmount - txfee). Also widen the int32_t txfee (which truncated
large CAmount fees) to CAmount and MoneyRange-validate.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
This commit is contained in:
2026-07-14 11:21:28 -05:00
parent a520441e3a
commit b5050d06c0

View File

@@ -6380,7 +6380,7 @@ void RegisterWalletRPCCommands(CRPCTable &tableRPC)
UniValue opreturn_burn(const UniValue& params, bool fHelp, const CPubKey& mypk)
{
std::vector<uint8_t> vHexStr; CScript opret; int32_t txfee = 10000;CPubKey myPubkey;
std::vector<uint8_t> vHexStr; CScript opret; CAmount txfee = 10000;CPubKey myPubkey;
if (fHelp || (params.size() < 2) || (params.size() > 4) )
{
throw runtime_error(
@@ -6413,6 +6413,9 @@ UniValue opreturn_burn(const UniValue& params, bool fHelp, const CPubKey& mypk)
if ( params.size() > 2 )
txfee = AmountFromValue(params[2]);
if ( !MoneyRange(nAmount) || !MoneyRange(txfee) || !MoneyRange(nAmount + txfee) )
throw JSONRPCError(RPC_TYPE_ERROR, "burn_amount + txfee out of range.");
if (!EnsureWalletIsAvailable(fHelp))
throw JSONRPCError(RPC_TYPE_ERROR, "wallet is locked or unavailable.");
EnsureWalletIsUnlocked();
@@ -6425,12 +6428,17 @@ UniValue opreturn_burn(const UniValue& params, bool fHelp, const CPubKey& mypk)
CMutableTransaction mtx = CreateNewContextualCMutableTransaction(Params().GetConsensus(), hush_nextheight());
int64_t normalInputs = AddNormalinputs(mtx, myPubkey, nAmount+txfee, 60);
if (normalInputs < nAmount)
if (normalInputs < nAmount+txfee)
throw runtime_error("insufficient funds\n");
opret << OP_RETURN << E_MARSHAL(ss << vHexStr);
mtx.vout.push_back(CTxOut(nAmount,opret));
// Return the unspent surplus (selected inputs - burn amount - txfee) as change to a
// wallet-owned address; without this the entire surplus is silently paid as miner fee.
CAmount change = normalInputs - nAmount - txfee;
if ( change > 0 )
mtx.vout.push_back(CTxOut(change, GetScriptForDestination(myPubkey.GetID())));
ret.push_back(Pair("hex", EncodeHexTx(mtx)));
return(ret);
}