Introduce WALLET_INCREMENTAL_RELAY_FEE

Have wallet's default bump value be higher than the default incrementalRelayFee to future proof against changes to incremental relay fee.  Only applies when not setting the fee rate directly.

2 files changed, 14 insertions, 4 deletions

diff --git a/src/wallet/rpcwallet.cpp b/src/wallet/rpcwallet.cpp
index 9ae36653b8..6517bae52c 100644
--- a/src/wallet/rpcwallet.cpp
+++ b/src/wallet/rpcwallet.cpp
@@ -2786,11 +2786,19 @@ UniValue bumpfee(const JSONRPCRequest& request)
     CFeeRate nOldFeeRate(nOldFee, txSize);
     CAmount nNewFee;
     CFeeRate nNewFeeRate;
+    // The wallet uses a conservative WALLET_INCREMENTAL_RELAY_FEE value to
+    // future proof against changes to network wide policy for incremental relay
+    // fee that our node may not be aware of.
+    CFeeRate walletIncrementalRelayFee = CFeeRate(WALLET_INCREMENTAL_RELAY_FEE);
+    if (::incrementalRelayFee > walletIncrementalRelayFee) {
+        walletIncrementalRelayFee = ::incrementalRelayFee;
+    }
 
     if (totalFee > 0) {
         CAmount minTotalFee = nOldFeeRate.GetFee(maxNewTxSize) + ::incrementalRelayFee.GetFee(maxNewTxSize);
         if (totalFee < minTotalFee) {
-            throw JSONRPCError(RPC_INVALID_PARAMETER, strprintf("Invalid totalFee, must be at least %s (oldFee %s + relayFee %s)", FormatMoney(minTotalFee), nOldFeeRate.GetFee(maxNewTxSize), ::incrementalRelayFee.GetFee(maxNewTxSize)));
+            throw JSONRPCError(RPC_INVALID_PARAMETER, strprintf("Insufficient totalFee, must be at least %s (oldFee %s + incrementalFee %s)",
+                                                                FormatMoney(minTotalFee), FormatMoney(nOldFeeRate.GetFee(maxNewTxSize)), FormatMoney(::incrementalRelayFee.GetFee(maxNewTxSize))));
         }
         nNewFee = totalFee;
         nNewFeeRate = CFeeRate(totalFee, maxNewTxSize);
@@ -2806,9 +2814,9 @@ UniValue bumpfee(const JSONRPCRequest& request)
 
         nNewFeeRate = CFeeRate(nNewFee, maxNewTxSize);
 
-        // new fee rate must be at least old rate + minimum incremental relay rate
-        if (nNewFeeRate.GetFeePerK() < nOldFeeRate.GetFeePerK() + ::incrementalRelayFee.GetFeePerK()) {
-            nNewFeeRate = CFeeRate(nOldFeeRate.GetFeePerK() + ::incrementalRelayFee.GetFeePerK());
+        // New fee rate must be at least old rate + minimum incremental relay rate
+        if (nNewFeeRate.GetFeePerK() < nOldFeeRate.GetFeePerK() + walletIncrementalRelayFee.GetFeePerK()) {
+            nNewFeeRate = CFeeRate(nOldFeeRate.GetFeePerK() + walletIncrementalRelayFee.GetFeePerK());
             nNewFee = nNewFeeRate.GetFee(maxNewTxSize);
         }
     }
diff --git a/src/wallet/wallet.h b/src/wallet/wallet.h
index f95c0589d6..764a7aa268 100644
--- a/src/wallet/wallet.h
+++ b/src/wallet/wallet.h
@@ -48,6 +48,8 @@ static const CAmount DEFAULT_TRANSACTION_FEE = 0;
 static const CAmount DEFAULT_FALLBACK_FEE = 20000;
 //! -mintxfee default
 static const CAmount DEFAULT_TRANSACTION_MINFEE = 1000;
+//! minimum recommended increment for BIP 125 replacement txs
+static const CAmount WALLET_INCREMENTAL_RELAY_FEE = 5000;
 //! target minimum change amount
 static const CAmount MIN_CHANGE = CENT;
 //! final minimum change amount after paying for fees