rpc bumpfee: add fee_rate argument

src/wallet/feebumper.cpp

@@ -258,7 +258,12 @@ Result CreateRateBumpTransaction(CWallet* wallet, const uint256& txid, const CCo
         }
     }
 
+    if (coin_control.m_feerate) {
+        // The user provided a feeRate argument.
+    } else {
+        // The user did not provide a feeRate argument
         new_coin_control.m_feerate = EstimateFeeRate(wallet, wtx, new_coin_control, old_fee);
+    }
 
     // Fill in required inputs we are double-spending(all of them)
     // N.B.: bip125 doesn't require all the inputs in the replaced transaction to be

src/wallet/rpcwallet.cpp

@@ -3290,7 +3290,7 @@ static UniValue bumpfee(const JSONRPCRequest& request)
                 "The command will fail if the wallet or mempool contains a transaction that spends one of T's outputs.\n"
                 "By default, the new fee will be calculated automatically using estimatesmartfee.\n"
                 "The user can specify a confirmation target for estimatesmartfee.\n"
-                "Alternatively, the user can specify totalFee (DEPRECATED), or use RPC settxfee to set a higher fee rate.\n"
+                "Alternatively, the user can specify totalFee (DEPRECATED), or fee_rate (" + CURRENCY_UNIT + " per kB) for the new transaction .\n"
                 "At a minimum, the new fee rate must be high enough to pay an additional new relay fee (incrementalfee\n"
                 "returned by getnetworkinfo) to enter the node's mempool.\n",
                 {
@@ -3302,6 +3302,9 @@ static UniValue bumpfee(const JSONRPCRequest& request)
             "                         In rare cases, the actual fee paid might be slightly higher than the specified\n"
             "                         totalFee if the tx change output has to be removed because it is too close to\n"
             "                         the dust threshold."},
+                            {"fee_rate", RPCArg::Type::NUM, /* default */ "fallback to 'confTarget'", "FeeRate (NOT total fee) to pay, in " + CURRENCY_UNIT + " per kB\n"
+            "                         Specify a fee rate instead of relying on the built-in fee estimator.\n"
+            "                         Must be at least 0.0001 BTC per kB higher than the current transaction fee rate.\n"},
                             {"replaceable", RPCArg::Type::BOOL, /* default */ "true", "Whether the new transaction should still be\n"
             "                         marked bip-125 replaceable. If true, the sequence numbers in the transaction will\n"
             "                         be left unchanged from the original. If false, any input sequence numbers in the\n"
@@ -3343,13 +3346,15 @@ static UniValue bumpfee(const JSONRPCRequest& request)
             {
                 {"confTarget", UniValueType(UniValue::VNUM)},
                 {"totalFee", UniValueType(UniValue::VNUM)},
+                {"fee_rate", UniValueType(UniValue::VNUM)},
                 {"replaceable", UniValueType(UniValue::VBOOL)},
                 {"estimate_mode", UniValueType(UniValue::VSTR)},
             },
             true, true);
-
+        if (options.exists("confTarget") && (options.exists("totalFee") || options.exists("fee_rate"))) {
-        if (options.exists("confTarget") && options.exists("totalFee")) {
+            throw JSONRPCError(RPC_INVALID_PARAMETER, "confTarget can't be set with totalFee or fee_rate. Please provide either a confirmation target in blocks for automatic fee estimation, or an explicit fee rate.");
-            throw JSONRPCError(RPC_INVALID_PARAMETER, "confTarget and totalFee options should not both be set. Please provide either a confirmation target for fee estimation or an explicit total fee for the transaction.");
+        } else if (options.exists("fee_rate") && options.exists("totalFee")) {
+            throw JSONRPCError(RPC_INVALID_PARAMETER, "fee_rate can't be set along with totalFee.");
         } else if (options.exists("confTarget")) { // TODO: alias this to conf_target
             coin_control.m_confirm_target = ParseConfirmTarget(options["confTarget"], pwallet->chain().estimateMaxBlocks());
         } else if (options.exists("totalFee")) {
@@ -3360,6 +3365,12 @@ static UniValue bumpfee(const JSONRPCRequest& request)
             if (totalFee <= 0) {
                 throw JSONRPCError(RPC_INVALID_PARAMETER, strprintf("Invalid totalFee %s (must be greater than 0)", FormatMoney(totalFee)));
             }
+        } else if (options.exists("fee_rate")) {
+            CFeeRate fee_rate(AmountFromValue(options["fee_rate"]));
+            if (fee_rate <= 0) {
+                throw JSONRPCError(RPC_INVALID_PARAMETER, strprintf("Invalid fee_rate %s (must be greater than 0)", fee_rate.ToString()));
+            }
+            coin_control.m_feerate = fee_rate;
         }
 
         if (options.exists("replaceable")) {