Merge #16373: bumpfee: Return PSBT when wallet has privkeys disabled

091a876664af4427db670ea8244d713b1b840048 Test watchonly wallet bumpfee with PSBT return (Gregory Sanders)
e9b4f9419cc778b5164708991a55014abef6c5f9 bumpfee: Return PSBT when wallet has privkeys disabled (Gregory Sanders)
75a5e478b631d3d0821d003300c4eae3c8433973 Change bumpfee to use watch-only funds for legacy watchonly wallets (Gregory Sanders)

Pull request description:

  The main use-case here is for using with watch-only wallets with PSBT-signing cold wallets of all kinds.

ACKs for top commit:
  achow101:
    ACK 091a876664af4427db670ea8244d713b1b840048
  Sjors:
    Tested ACK 091a876664af4427db670ea8244d713b1b840048
  meshcollider:
    utACK 091a876664af4427db670ea8244d713b1b840048

Tree-SHA512: f7cf663e1af0b029e5c99eac88c5fdc3bc9e9a3841da8a608e8a9957e9bcf6a78864b8c2706fcaf78a480ffe11badd80c4fad29f97c0bb929e0470fafda5c22e

3 files changed, 123 insertions, 19 deletions

diff --git a/src/wallet/feebumper.cpp b/src/wallet/feebumper.cpp
index 36588eb7d1..b93b9ef1bc 100644
--- a/src/wallet/feebumper.cpp
+++ b/src/wallet/feebumper.cpp
@@ -47,7 +47,8 @@ static feebumper::Result PreconditionChecks(const CWallet& wallet, const CWallet
 
     // check that original tx consists entirely of our inputs
     // if not, we can't bump the fee, because the wallet has no way of knowing the value of the other inputs (thus the fee)
-    if (!wallet.IsAllFromMe(*wtx.tx, ISMINE_SPENDABLE)) {
+    isminefilter filter = wallet.GetLegacyScriptPubKeyMan() && wallet.IsWalletFlagSet(WALLET_FLAG_DISABLE_PRIVATE_KEYS) ? ISMINE_WATCH_ONLY : ISMINE_SPENDABLE;
+    if (!wallet.IsAllFromMe(*wtx.tx, filter)) {
         errors.push_back("Transaction contains inputs that don't belong to this wallet");
         return feebumper::Result::WALLET_ERROR;
     }
@@ -78,7 +79,8 @@ static feebumper::Result CheckFeeRate(const CWallet& wallet, const CWalletTx& wt
     CFeeRate incrementalRelayFee = std::max(wallet.chain().relayIncrementalFee(), CFeeRate(WALLET_INCREMENTAL_RELAY_FEE));
 
     // Given old total fee and transaction size, calculate the old feeRate
-    CAmount old_fee = wtx.GetDebit(ISMINE_SPENDABLE) - wtx.tx->GetValueOut();
+    isminefilter filter = wallet.GetLegacyScriptPubKeyMan() && wallet.IsWalletFlagSet(WALLET_FLAG_DISABLE_PRIVATE_KEYS) ? ISMINE_WATCH_ONLY : ISMINE_SPENDABLE;
+    CAmount old_fee = wtx.GetDebit(filter) - wtx.tx->GetValueOut();
     const int64_t txSize = GetVirtualTransactionSize(*(wtx.tx));
     CFeeRate nOldFeeRate(old_fee, txSize);
     // Min total fee is old fee + relay fee
@@ -195,7 +197,8 @@ Result CreateTotalBumpTransaction(const CWallet* wallet, const uint256& txid, co
     }
 
     // calculate the old fee and fee-rate
-    old_fee = wtx.GetDebit(ISMINE_SPENDABLE) - wtx.tx->GetValueOut();
+    isminefilter filter = wallet->GetLegacyScriptPubKeyMan() && wallet->IsWalletFlagSet(WALLET_FLAG_DISABLE_PRIVATE_KEYS) ? ISMINE_WATCH_ONLY : ISMINE_SPENDABLE;
+    old_fee = wtx.GetDebit(filter) - wtx.tx->GetValueOut();
     CFeeRate nOldFeeRate(old_fee, txSize);
     // The wallet uses a conservative WALLET_INCREMENTAL_RELAY_FEE value to
     // future proof against changes to network wide policy for incremental relay
@@ -308,7 +311,8 @@ Result CreateRateBumpTransaction(CWallet& wallet, const uint256& txid, const CCo
         }
     }
 
-    old_fee = wtx.GetDebit(ISMINE_SPENDABLE) - wtx.tx->GetValueOut();
+    isminefilter filter = wallet.GetLegacyScriptPubKeyMan() && wallet.IsWalletFlagSet(WALLET_FLAG_DISABLE_PRIVATE_KEYS) ? ISMINE_WATCH_ONLY : ISMINE_SPENDABLE;
+    old_fee = wtx.GetDebit(filter) - wtx.tx->GetValueOut();
 
     if (coin_control.m_feerate) {
         // The user provided a feeRate argument.
diff --git a/src/wallet/rpcwallet.cpp b/src/wallet/rpcwallet.cpp
index 5041b2244e..5978c60d84 100644
--- a/src/wallet/rpcwallet.cpp
+++ b/src/wallet/rpcwallet.cpp
@@ -3365,10 +3365,11 @@ static UniValue bumpfee(const JSONRPCRequest& request)
                 },
                 RPCResult{
             "{\n"
-            "  \"txid\":    \"value\",   (string)  The id of the new transaction\n"
-            "  \"origfee\":  n,         (numeric) Fee of the replaced transaction\n"
-            "  \"fee\":      n,         (numeric) Fee of the new transaction\n"
-            "  \"errors\":  [ str... ] (json array of strings) Errors encountered during processing (may be empty)\n"
+            "  \"psbt\":    \"psbt\",    (string) The base64-encoded unsigned PSBT of the new transaction. Only returned when wallet private keys are disabled.\n"
+            "  \"txid\":    \"value\",   (string) The id of the new transaction. Only returned when wallet private keys are enabled.\n"
+            "  \"origfee\":  n,        (numeric) The fee of the replaced transaction.\n"
+            "  \"fee\":      n,        (numeric) The fee of the new transaction.\n"
+            "  \"errors\":  [ str... ] (json array of strings) Errors encountered during processing (may be empty).\n"
             "}\n"
                 },
                 RPCExamples{
@@ -3380,10 +3381,12 @@ static UniValue bumpfee(const JSONRPCRequest& request)
     RPCTypeCheck(request.params, {UniValue::VSTR, UniValue::VOBJ});
     uint256 hash(ParseHashV(request.params[0], "txid"));
 
+    CCoinControl coin_control;
+    coin_control.fAllowWatchOnly = pwallet->IsWalletFlagSet(WALLET_FLAG_DISABLE_PRIVATE_KEYS);
     // optional parameters
     CAmount totalFee = 0;
-    CCoinControl coin_control;
     coin_control.m_signal_bip125_rbf = true;
+
     if (!request.params[1].isNull()) {
         UniValue options = request.params[1];
         RPCTypeCheckObj(options,
@@ -3468,17 +3471,32 @@ static UniValue bumpfee(const JSONRPCRequest& request)
         }
     }
 
-    // sign bumped transaction
-    if (!feebumper::SignTransaction(*pwallet, mtx)) {
-        throw JSONRPCError(RPC_WALLET_ERROR, "Can't sign transaction.");
-    }
-    // commit the bumped transaction
-    uint256 txid;
-    if (feebumper::CommitTransaction(*pwallet, hash, std::move(mtx), errors, txid) != feebumper::Result::OK) {
-        throw JSONRPCError(RPC_WALLET_ERROR, errors[0]);
-    }
     UniValue result(UniValue::VOBJ);
-    result.pushKV("txid", txid.GetHex());
+
+    // If wallet private keys are enabled, return the new transaction id,
+    // otherwise return the base64-encoded unsigned PSBT of the new transaction.
+    if (!pwallet->IsWalletFlagSet(WALLET_FLAG_DISABLE_PRIVATE_KEYS)) {
+        if (!feebumper::SignTransaction(*pwallet, mtx)) {
+            throw JSONRPCError(RPC_WALLET_ERROR, "Can't sign transaction.");
+        }
+
+        uint256 txid;
+        if (feebumper::CommitTransaction(*pwallet, hash, std::move(mtx), errors, txid) != feebumper::Result::OK) {
+            throw JSONRPCError(RPC_WALLET_ERROR, errors[0]);
+        }
+
+        result.pushKV("txid", txid.GetHex());
+    } else {
+        PartiallySignedTransaction psbtx(mtx);
+        bool complete = false;
+        const TransactionError err = FillPSBT(pwallet, psbtx, complete, SIGHASH_ALL, false /* sign */, true /* bip32derivs */);
+        CHECK_NONFATAL(err == TransactionError::OK);
+        CHECK_NONFATAL(!complete);
+        CDataStream ssTx(SER_NETWORK, PROTOCOL_VERSION);
+        ssTx << psbtx;
+        result.pushKV("psbt", EncodeBase64(ssTx.str()));
+    }
+
     result.pushKV("origfee", ValueFromAmount(old_fee));
     result.pushKV("fee", ValueFromAmount(new_fee));
     UniValue result_errors(UniValue::VARR);
diff --git a/test/functional/wallet_bumpfee.py b/test/functional/wallet_bumpfee.py
index 0c08655833..4eb0d19a4f 100755
--- a/test/functional/wallet_bumpfee.py
+++ b/test/functional/wallet_bumpfee.py
@@ -78,6 +78,7 @@ class BumpFeeTest(BitcoinTestFramework):
         test_small_output_fails(rbf_node, dest_address)
         test_dust_to_fee(rbf_node, dest_address)
         test_settxfee(rbf_node, dest_address)
+        test_watchonly_psbt(self, peer_node, rbf_node, dest_address)
         test_rebumping(rbf_node, dest_address)
         test_rebumping_not_replaceable(rbf_node, dest_address)
         test_unconfirmed_not_spendable(rbf_node, rbf_node_address)
@@ -103,6 +104,7 @@ def test_simple_bumpfee_succeeds(self, mode, rbf_node, peer_node, dest_address):
     assert_equal(bumped_tx["errors"], [])
     assert bumped_tx["fee"] > -rbftx["fee"]
     assert_equal(bumped_tx["origfee"], -rbftx["fee"])
+    assert "psbt" not in bumped_tx
     # check that bumped_tx propagates, original tx was evicted and has a wallet conflict
     self.sync_mempools((rbf_node, peer_node))
     assert bumped_tx["txid"] in rbf_node.getrawmempool()
@@ -280,6 +282,86 @@ def test_maxtxfee_fails(test, rbf_node, dest_address):
     test.restart_node(1, test.extra_args[1])
     rbf_node.walletpassphrase(WALLET_PASSPHRASE, WALLET_PASSPHRASE_TIMEOUT)
 
+def test_watchonly_psbt(test, peer_node, rbf_node, dest_address):
+    priv_rec_desc = "wpkh([00000001/84'/1'/0']tprv8ZgxMBicQKsPd7Uf69XL1XwhmjHopUGep8GuEiJDZmbQz6o58LninorQAfcKZWARbtRtfnLcJ5MQ2AtHcQJCCRUcMRvmDUjyEmNUWwx8UbK/0/*)#rweraev0"
+    pub_rec_desc = rbf_node.getdescriptorinfo(priv_rec_desc)["descriptor"]
+    priv_change_desc = "wpkh([00000001/84'/1'/0']tprv8ZgxMBicQKsPd7Uf69XL1XwhmjHopUGep8GuEiJDZmbQz6o58LninorQAfcKZWARbtRtfnLcJ5MQ2AtHcQJCCRUcMRvmDUjyEmNUWwx8UbK/1/*)#j6uzqvuh"
+    pub_change_desc = rbf_node.getdescriptorinfo(priv_change_desc)["descriptor"]
+    # Create a wallet with private keys that can sign PSBTs
+    rbf_node.createwallet(wallet_name="signer", disable_private_keys=False, blank=True)
+    signer = rbf_node.get_wallet_rpc("signer")
+    assert signer.getwalletinfo()['private_keys_enabled']
+    result = signer.importmulti([{
+        "desc": priv_rec_desc,
+        "timestamp": 0,
+        "range": [0,1],
+        "internal": False,
+        "keypool": False # Keys can only be imported to the keypool when private keys are disabled
+    },
+    {
+        "desc": priv_change_desc,
+        "timestamp": 0,
+        "range": [0, 0],
+        "internal": True,
+        "keypool": False
+    }])
+    assert_equal(result, [{'success': True}, {'success': True}])
+
+    # Create another wallet with just the public keys, which creates PSBTs
+    rbf_node.createwallet(wallet_name="watcher", disable_private_keys=True, blank=True)
+    watcher = rbf_node.get_wallet_rpc("watcher")
+    assert not watcher.getwalletinfo()['private_keys_enabled']
+
+    result = watcher.importmulti([{
+        "desc": pub_rec_desc,
+        "timestamp": 0,
+        "range": [0,10],
+        "internal": False,
+        "keypool": True,
+        "watchonly": True
+    },
+    {
+        "desc": pub_change_desc,
+        "timestamp": 0,
+        "range": [0, 10],
+        "internal": True,
+        "keypool": True,
+        "watchonly": True
+    }])
+    assert_equal(result, [{'success': True}, {'success': True}])
+
+    funding_address1 = watcher.getnewaddress(address_type='bech32')
+    funding_address2 = watcher.getnewaddress(address_type='bech32')
+    peer_node.sendmany("", {funding_address1: 0.001, funding_address2: 0.001})
+    peer_node.generate(1)
+    test.sync_all()
+
+    # Create single-input PSBT for transaction to be bumped
+    psbt = watcher.walletcreatefundedpsbt([], {dest_address:0.0005}, 0, {"feeRate": 0.00001}, True)['psbt']
+    psbt_signed = signer.walletprocesspsbt(psbt=psbt, sign=True, sighashtype="ALL", bip32derivs=True)
+    psbt_final = watcher.finalizepsbt(psbt_signed["psbt"])
+    original_txid = watcher.sendrawtransaction(psbt_final["hex"])
+    assert_equal(len(watcher.decodepsbt(psbt)["tx"]["vin"]), 1)
+
+    # Bump fee, obnoxiously high to add additional watchonly input
+    bumped_psbt = watcher.bumpfee(original_txid, {"fee_rate":0.005})
+    assert_greater_than(len(watcher.decodepsbt(bumped_psbt['psbt'])["tx"]["vin"]), 1)
+    assert "txid" not in bumped_psbt
+    assert_equal(bumped_psbt["origfee"], -watcher.gettransaction(original_txid)["fee"])
+    assert not watcher.finalizepsbt(bumped_psbt["psbt"])["complete"]
+
+    # Sign bumped transaction
+    bumped_psbt_signed = signer.walletprocesspsbt(psbt=bumped_psbt["psbt"], sign=True, sighashtype="ALL", bip32derivs=True)
+    bumped_psbt_final = watcher.finalizepsbt(bumped_psbt_signed["psbt"])
+    assert bumped_psbt_final["complete"]
+
+    # Broadcast bumped transaction
+    bumped_txid = watcher.sendrawtransaction(bumped_psbt_final["hex"])
+    assert bumped_txid in rbf_node.getrawmempool()
+    assert original_txid not in rbf_node.getrawmempool()
+
+    rbf_node.unloadwallet("watcher")
+    rbf_node.unloadwallet("signer")
 
 def test_rebumping(rbf_node, dest_address):
     # check that re-bumping the original tx fails, but bumping the bumper succeeds