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feat: add use_cj feature to RPCs send, sendall and fundrawtransaction #7261

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Merged
PastaPastaPasta merged 1 commit into from
Aug 23, 2026
Merged

feat: add use_cj feature to RPCs send, sendall and fundrawtransaction #7261

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27 changes: 26 additions & 1 deletion src/wallet/rpc/spend.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -129,7 +129,7 @@ static UniValue FinishTransaction(const std::shared_ptr<CWallet> pwallet, const
CTransactionRef tx(MakeTransactionRef(std::move(mtx)));
result.pushKV("txid", tx->GetHash().GetHex());
if (add_to_wallet && !psbt_opt_in) {
pwallet->CommitTransaction(tx, {}, /*orderForm*/ {});
pwallet->CommitTransaction(tx, options["use_cj"].isTrue() ? mapValue_t{{"DS", "1"}} : mapValue_t{}, /*orderForm*/ {});
} else {
result.pushKV("hex", hex);
}
Expand Down Expand Up @@ -545,6 +545,7 @@ void FundTransaction(CWallet& wallet, CMutableTransaction& tx, CAmount& fee_out,
{"conf_target", UniValueType(UniValue::VNUM)},
{"estimate_mode", UniValueType(UniValue::VSTR)},
{"input_sizes", UniValueType(UniValue::VARR)},
{"use_cj", UniValueType(UniValue::VBOOL)},
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},
true, true);

Expand Down Expand Up @@ -595,6 +596,19 @@ void FundTransaction(CWallet& wallet, CMutableTransaction& tx, CAmount& fee_out,
if (options.exists("subtractFeeFromOutputs") || options.exists("subtract_fee_from_outputs") )
subtractFeeFromOutputs = (options.exists("subtract_fee_from_outputs") ? options["subtract_fee_from_outputs"] : options["subtractFeeFromOutputs"]).get_array();

if (options.exists("use_cj")) {
coinControl.UseCoinJoin(options["use_cj"].get_bool());
if (coinControl.IsUsingCoinJoin()) {
// Preset inputs stay in the transaction even though coin selection
// ignores non-mixed ones, so reject them here instead
for (const CTxIn& txin : tx.vin) {
if (!wallet.IsFullyMixed(txin.prevout)) {
throw JSONRPCError(RPC_INVALID_PARAMETER, strprintf("Input not available. UTXO (%s:%d) is not fully mixed.", txin.prevout.hash.ToString(), txin.prevout.n));
}
}
}
}
Comment on lines +599 to +610

@chatgpt-codex-connector chatgpt-codex-connector Bot Apr 13, 2026

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P1 Badge Reject non-mixed preset inputs when enabling use_cj

Setting options.use_cj=true here is unsafe for fundrawtransaction (and send when add_inputs=true) if callers provide preselected non-mixed inputs: SelectCoins skips those preset inputs under ONLY_FULLY_MIXED (in src/wallet/spend.cpp), but the RPC funding flow later keeps the original tx.vin entries when merging the funded transaction, so those non-CoinJoin inputs are still spent while fee/change were computed as if they were absent. In that path users can unintentionally spend non-CoinJoin funds and overpay fees, so this option should reject incompatible preset inputs instead of silently proceeding.

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SetFeeEstimateMode(wallet, coinControl, options["conf_target"], options["estimate_mode"], options["fee_rate"], override_min_fee);
}
} else {
Expand Down Expand Up @@ -776,6 +790,7 @@ RPCHelpMan fundrawtransaction()
},
},
},
{"use_cj", RPCArg::Type::BOOL, RPCArg::Default{false}, "Use CoinJoin funds only"},
},
FundTxDoc()),
RPCArgOptions{.oneline_description="options"}},
Expand Down Expand Up @@ -982,6 +997,7 @@ RPCHelpMan send()
{"vout_index", RPCArg::Type::NUM, RPCArg::Optional::OMITTED, "The zero-based output index, before a change output is added."},
},
},
{"use_cj", RPCArg::Type::BOOL, RPCArg::Default{false}, "Use CoinJoin funds only"},
},
FundTxDoc()),
RPCArgOptions{.oneline_description="options"}},
Expand Down Expand Up @@ -1088,6 +1104,7 @@ RPCHelpMan sendall()
{"lock_unspents", RPCArg::Type::BOOL, RPCArg::Default{false}, "Lock selected unspent outputs"},
{"psbt", RPCArg::Type::BOOL, RPCArg::DefaultHint{"automatic"}, "Always return a PSBT, implies add_to_wallet=false."},
{"send_max", RPCArg::Type::BOOL, RPCArg::Default{false}, "When true, only use UTXOs that can pay for their own fees to maximize the output amount. When 'false' (default), no UTXO is left behind. send_max is incompatible with providing specific inputs."},
{"use_cj", RPCArg::Type::BOOL, RPCArg::Default{false}, "Use CoinJoin funds only"},
},
FundTxDoc()
),
Expand Down Expand Up @@ -1162,6 +1179,10 @@ RPCHelpMan sendall()

coin_control.fAllowWatchOnly = ParseIncludeWatchonly(options["include_watching"], *pwallet);

if (options.exists("use_cj")) {
coin_control.UseCoinJoin(options["use_cj"].get_bool());
}
Comment on lines +1182 to +1184

@chatgpt-codex-connector chatgpt-codex-connector Bot Mar 30, 2026

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P2 Badge Enforce use_cj for manually specified sendall inputs

When sendall is called with both options.use_cj=true and options.inputs, this new flag does not actually constrain the provided inputs to fully mixed coins: the inputs branch later accepts any wallet UTXO and skips the AvailableCoins(..., &coin_control, ...) filtering path. In this scenario, callers can unintentionally spend non-CoinJoin funds despite opting into CoinJoin-only behavior, so this should either validate each specified input as fully mixed or reject the combination as incompatible.

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FeeCalculation fee_calc_out;
CFeeRate fee_rate{GetMinimumFeeRate(*pwallet, coin_control, &fee_calc_out)};
// Do not, ever, assume that it's fine to change the fee rate if the user has explicitly
Expand Down Expand Up @@ -1190,6 +1211,9 @@ RPCHelpMan sendall()
if (!tx || input.prevout.n >= tx->tx->vout.size() || !(pwallet->IsMine(tx->tx->vout[input.prevout.n]) & (coin_control.fAllowWatchOnly ? ISMINE_ALL : ISMINE_SPENDABLE))) {
throw JSONRPCError(RPC_INVALID_PARAMETER, strprintf("Input not found. UTXO (%s:%d) is not part of wallet.", input.prevout.hash.ToString(), input.prevout.n));
}
if (coin_control.IsUsingCoinJoin() && !pwallet->IsFullyMixed(input.prevout)) {
throw JSONRPCError(RPC_INVALID_PARAMETER, strprintf("Input not available. UTXO (%s:%d) is not fully mixed.", input.prevout.hash.ToString(), input.prevout.n));
}
total_input_value += tx->tx->vout[input.prevout.n].nValue;
}
} else {
Expand Down Expand Up @@ -1418,6 +1442,7 @@ RPCHelpMan walletcreatefundedpsbt()
{"vout_index", RPCArg::Type::NUM, RPCArg::Optional::OMITTED, "The zero-based output index, before a change output is added."},
},
},
{"use_cj", RPCArg::Type::BOOL, RPCArg::Default{false}, "Use CoinJoin funds only"},
},
FundTxDoc()),
RPCArgOptions{.oneline_description="options"}},
Expand Down
33 changes: 33 additions & 0 deletions test/functional/rpc_coinjoin.py
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Original file line number Diff line number Diff line change
Expand Up @@ -6,6 +6,7 @@
import random

from test_framework.test_framework import BitcoinTestFramework
from test_framework.blocktools import COINBASE_MATURITY
from test_framework.messages import (
COIN,
MAX_MONEY,
Expand Down Expand Up @@ -55,6 +56,12 @@ def run_test(self):
self.test_coinjoinsalt(w1)
w1.unloadwallet()

node.createwallet(wallet_name='w3')
w3 = node.get_wallet_rpc('w3')
self.generatetoaddress(node, COINBASE_MATURITY + 1, w3.getnewaddress())
self.test_use_cj_option(w3)
w3.unloadwallet()

if not self.options.descriptors:
node.createwallet(wallet_name='w_keypool', blank=False, disable_private_keys=False)
w_keypool = node.get_wallet_rpc('w_keypool')
Expand Down Expand Up @@ -118,6 +125,32 @@ def test_newkeypool_stops_mixing(self, node):
node.newkeypool()
assert_equal(node.getcoinjoininfo()['running'], False)

def test_use_cj_option(self, node):
self.log.info('"use_cj" option should spend fully mixed coins only')
addr = node.getnewaddress()
utxo = node.listunspent()[0]
input_ref = {'txid': utxo['txid'], 'vout': utxo['vout']}

# Automatic coin selection should find no fully mixed coins in this wallet
assert_raises_rpc_error(-4, 'Unable to locate enough mixed funds for this transaction.',
node.send, outputs={addr: 1}, options={'use_cj': True})
assert_raises_rpc_error(-6, 'Total value of UTXO pool too low to pay for transaction.',
node.sendall, recipients=[addr], options={'use_cj': True})

# Preset non-mixed inputs should be rejected instead of silently spent
not_mixed_error = f"Input not available. UTXO ({utxo['txid']}:{utxo['vout']}) is not fully mixed."
raw_tx = node.createrawtransaction([input_ref], {addr: 1})
assert_raises_rpc_error(-8, not_mixed_error, node.fundrawtransaction, raw_tx, {'use_cj': True})
assert_raises_rpc_error(-8, not_mixed_error, node.walletcreatefundedpsbt,
[input_ref], {addr: 1}, 0, {'use_cj': True})
assert_raises_rpc_error(-8, not_mixed_error, node.send,
outputs={addr: 1}, options={'inputs': [input_ref], 'use_cj': True})
assert_raises_rpc_error(-8, not_mixed_error, node.sendall,
recipients=[addr], options={'inputs': [input_ref], 'use_cj': True})

# The same input is spendable once "use_cj" is not requested
assert_equal(node.sendall(recipients=[addr], options={'inputs': [input_ref]})['complete'], True)

def test_setcoinjoinamount(self, node):
self.log.info('"setcoinjoinamount" should update mixing target')
# Test normal and large values
Expand Down
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