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

2 files changed, 41 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);