Merge bitcoin/bitcoin#21576: rpc, gui: bumpfee signer support

2c07cfa gui: bumpfee signer support (Sjors Provoost)
7e02a33 rpc: bumpfee signer support (Sjors Provoost)
304ece9 rpc: document bools in FillPSBT() calls (Sjors Provoost)

Pull request description:

  The `bumpfee` RPC call and GUI fee bump interface now work with an external signer.

ACKs for top commit:
  achow101:
    ACK 2c07cfa
  furszy:
    code review ACK 2c07cfa
  jarolrod:
    tACK 2c07cfa

Tree-SHA512: 0c7b931f76fac67c9e33b9b935f29af6f69ac67a5ffcc586ed2f1676feac427735b1d971723b29ef332bb6fb5762949598ebbf728587e8f0ded95a9bfbb3e7a4

Author: achow101

src/qt/walletmodel.cpp

@@ -522,7 +522,9 @@ bool WalletModel::bumpFee(uint256 hash, uint256& new_hash)
         questionString.append(tr("Warning: This may pay the additional fee by reducing change outputs or adding inputs, when necessary. It may add a new change output if one does not already exist. These changes may potentially leak privacy."));
     }
 
-    auto confirmationDialog = new SendConfirmationDialog(tr("Confirm fee bump"), questionString, "", "", SEND_CONFIRM_DELAY, !m_wallet->privateKeysDisabled(), getOptionsModel()->getEnablePSBTControls(), nullptr);
+    const bool enable_send{!wallet().privateKeysDisabled() || wallet().hasExternalSigner()};
+    const bool always_show_unsigned{getOptionsModel()->getEnablePSBTControls()};
+    auto confirmationDialog = new SendConfirmationDialog(tr("Confirm fee bump"), questionString, "", "", SEND_CONFIRM_DELAY, enable_send, always_show_unsigned, nullptr);
     confirmationDialog->setAttribute(Qt::WA_DeleteOnClose);
     // TODO: Replace QDialog::exec() with safer QDialog::show().
     const auto retval = static_cast<QMessageBox::StandardButton>(confirmationDialog->exec());
@@ -540,6 +542,7 @@ bool WalletModel::bumpFee(uint256 hash, uint256& new_hash)
 
     // Short-circuit if we are returning a bumped transaction PSBT to clipboard
     if (retval == QMessageBox::Save) {
+        // "Create Unsigned" clicked
         PartiallySignedTransaction psbtx(mtx);
         bool complete = false;
         const TransactionError err = wallet().fillPSBT(SIGHASH_ALL, /*sign=*/false, /*bip32derivs=*/true, nullptr, psbtx, complete);
@@ -555,7 +558,7 @@ bool WalletModel::bumpFee(uint256 hash, uint256& new_hash)
         return true;
     }
 
-    assert(!m_wallet->privateKeysDisabled());
+    assert(!m_wallet->privateKeysDisabled() || wallet().hasExternalSigner());
 
     // sign bumped transaction
     if (!m_wallet->signBumpTransaction(mtx)) {

src/wallet/feebumper.cpp

@@ -293,7 +293,22 @@ Result CreateRateBumpTransaction(CWallet& wallet, const uint256& txid, const CCo
 
 bool SignTransaction(CWallet& wallet, CMutableTransaction& mtx) {
     LOCK(wallet.cs_wallet);
-    return wallet.SignTransaction(mtx);
+
+    if (wallet.IsWalletFlagSet(WALLET_FLAG_EXTERNAL_SIGNER)) {
+        // Make a blank psbt
+        PartiallySignedTransaction psbtx(mtx);
+
+        // First fill transaction with our data without signing,
+        // so external signers are not asked to sign more than once.
+        bool complete;
+        wallet.FillPSBT(psbtx, complete, SIGHASH_ALL, false /* sign */, true /* bip32derivs */);
+        const TransactionError err = wallet.FillPSBT(psbtx, complete, SIGHASH_ALL, true /* sign */, false  /* bip32derivs */);
+        if (err != TransactionError::OK) return false;
+        complete = FinalizeAndExtractPSBT(psbtx, mtx);
+        return complete;
+    } else {
+        return wallet.SignTransaction(mtx);
+    }
 }
 
 Result CommitTransaction(CWallet& wallet, const uint256& txid, CMutableTransaction&& mtx, std::vector<bilingual_str>& errors, uint256& bumped_txid)

src/wallet/rpc/spend.cpp

@@ -82,10 +82,10 @@ static UniValue FinishTransaction(const std::shared_ptr<CWallet> pwallet, const
     PartiallySignedTransaction psbtx(rawTx);
 
     // First fill transaction with our data without signing,
-    // so external signers are not asked sign more than once.
+    // so external signers are not asked to sign more than once.
     bool complete;
-    pwallet->FillPSBT(psbtx, complete, SIGHASH_DEFAULT, false, true);
-    const TransactionError err{pwallet->FillPSBT(psbtx, complete, SIGHASH_DEFAULT, true, false)};
+    pwallet->FillPSBT(psbtx, complete, SIGHASH_DEFAULT, /*sign=*/false, /*bip32derivs=*/true);
+    const TransactionError err{pwallet->FillPSBT(psbtx, complete, SIGHASH_DEFAULT, /*sign=*/true, /*bip32derivs=*/false)};
     if (err != TransactionError::OK) {
         throw JSONRPCTransactionError(err);
     }
@@ -993,7 +993,7 @@ static RPCHelpMan bumpfee_helper(std::string method_name)
     std::shared_ptr<CWallet> const pwallet = GetWalletForJSONRPCRequest(request);
     if (!pwallet) return UniValue::VNULL;
 
-    if (pwallet->IsWalletFlagSet(WALLET_FLAG_DISABLE_PRIVATE_KEYS) && !want_psbt) {
+    if (pwallet->IsWalletFlagSet(WALLET_FLAG_DISABLE_PRIVATE_KEYS) && !pwallet->IsWalletFlagSet(WALLET_FLAG_EXTERNAL_SIGNER) && !want_psbt) {
         throw JSONRPCError(RPC_WALLET_ERROR, "bumpfee is not available with wallets that have private keys disabled. Use psbtbumpfee instead.");
     }
 
@@ -1071,6 +1071,9 @@ static RPCHelpMan bumpfee_helper(std::string method_name)
     // For psbtbumpfee, return the base64-encoded unsigned PSBT of the new transaction.
     if (!want_psbt) {
         if (!feebumper::SignTransaction(*pwallet, mtx)) {
+            if (pwallet->IsWalletFlagSet(WALLET_FLAG_EXTERNAL_SIGNER)) {
+                throw JSONRPCError(RPC_WALLET_ERROR, "Transaction incomplete. Try psbtbumpfee instead.");
+            }
             throw JSONRPCError(RPC_WALLET_ERROR, "Can't sign transaction.");
         }
 
@@ -1667,7 +1670,7 @@ RPCHelpMan walletcreatefundedpsbt()
     // Fill transaction with out data but don't sign
     bool bip32derivs = request.params[4].isNull() ? true : request.params[4].get_bool();
     bool complete = true;
-    const TransactionError err{wallet.FillPSBT(psbtx, complete, 1, false, bip32derivs)};
+    const TransactionError err{wallet.FillPSBT(psbtx, complete, 1, /*sign=*/false, /*bip32derivs=*/bip32derivs)};
     if (err != TransactionError::OK) {
         throw JSONRPCTransactionError(err);
     }

test/functional/wallet_signer.py

@@ -13,6 +13,7 @@
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import (
     assert_equal,
+    assert_greater_than,
     assert_raises_rpc_error,
 )
 
@@ -169,7 +170,7 @@ def test_valid_signer(self):
         assert_equal(result[1], {'success': True})
         assert_equal(mock_wallet.getwalletinfo()["txcount"], 1)
         dest = self.nodes[0].getnewaddress(address_type='bech32')
-        mock_psbt = mock_wallet.walletcreatefundedpsbt([], {dest:0.5}, 0, {}, True)['psbt']
+        mock_psbt = mock_wallet.walletcreatefundedpsbt([], {dest:0.5}, 0, {'replaceable': True}, True)['psbt']
         mock_psbt_signed = mock_wallet.walletprocesspsbt(psbt=mock_psbt, sign=True, sighashtype="ALL", bip32derivs=True)
         mock_psbt_final = mock_wallet.finalizepsbt(mock_psbt_signed["psbt"])
         mock_tx = mock_psbt_final["hex"]
@@ -209,6 +210,7 @@ def test_valid_signer(self):
 
         self.log.info('Test send using hww1')
 
+        # Don't broadcast transaction yet so the RPC returns the raw hex
         res = hww.send(outputs={dest:0.5},options={"add_to_wallet": False})
         assert(res["complete"])
         assert_equal(res["hex"], mock_tx)
@@ -218,6 +220,25 @@ def test_valid_signer(self):
         res = hww.sendall(recipients=[{dest:0.5}, hww.getrawchangeaddress()],options={"add_to_wallet": False})
         assert(res["complete"])
         assert_equal(res["hex"], mock_tx)
+        # Broadcast transaction so we can bump the fee
+        hww.sendrawtransaction(res["hex"])
+
+        self.log.info('Prepare fee bumped mock PSBT')
+
+        # Now that the transaction is broadcast, bump fee in mock wallet:
+        orig_tx_id = res["txid"]
+        mock_psbt_bumped = mock_wallet.psbtbumpfee(orig_tx_id)["psbt"]
+        mock_psbt_bumped_signed = mock_wallet.walletprocesspsbt(psbt=mock_psbt_bumped, sign=True, sighashtype="ALL", bip32derivs=True)
+
+        with open(os.path.join(self.nodes[1].cwd, "mock_psbt"), "w", encoding="utf8") as f:
+            f.write(mock_psbt_bumped_signed["psbt"])
+
+        self.log.info('Test bumpfee using hww1')
+
+        # Bump fee
+        res = hww.bumpfee(orig_tx_id)
+        assert_greater_than(res["fee"], res["origfee"])
+        assert_equal(res["errors"], [])
 
         # # Handle error thrown by script
         # self.set_mock_result(self.nodes[4], "2")