Merge #11882: Disable default fallbackfee on mainnet

3f592b8 [QA] add wallet-rbf test (Jonas Schnelli)
8222e05 Disable wallet fallbackfee by default on mainnet (Jonas Schnelli)

Pull request description:

  Removes the default fallback fee on mainnet (but keeps it on testnet/regtest).

  Transactions using the fallbackfee in case the fallback fee has not been set are getting rejected.

Tree-SHA512: e54d2594b7f954e640cc513a18b0bfbe189f15e15bdeed4fe02b7677f939bca1731fef781b073127ffd4ce08a595fb118259b8826cdaa077ff7d5ae9495810db

5 files changed, 16 insertions, 0 deletions

diff --git a/src/wallet/fees.cpp b/src/wallet/fees.cpp
index 73985dcf25..385fdc963a 100644
--- a/src/wallet/fees.cpp
+++ b/src/wallet/fees.cpp
@@ -53,6 +53,9 @@ CAmount GetMinimumFee(unsigned int nTxBytes, const CCoinControl& coin_control, c
             // if we don't have enough data for estimateSmartFee, then use fallbackFee
             fee_needed = CWallet::fallbackFee.GetFee(nTxBytes);
             if (feeCalc) feeCalc->reason = FeeReason::FALLBACK;
+
+            // directly return if fallback fee is disabled (feerate 0 == disabled)
+            if (CWallet::fallbackFee.GetFee(1000) == 0) return fee_needed;
         }
         // Obey mempool min fee when using smart fee estimation
         CAmount min_mempool_fee = pool.GetMinFee(gArgs.GetArg("-maxmempool", DEFAULT_MAX_MEMPOOL_SIZE) * 1000000).GetFee(nTxBytes);
diff --git a/src/wallet/init.cpp b/src/wallet/init.cpp
index 74036f4f0f..9ac48bff77 100644
--- a/src/wallet/init.cpp
+++ b/src/wallet/init.cpp
@@ -5,6 +5,7 @@
 
 #include <wallet/init.h>
 
+#include <chainparams.h>
 #include <net.h>
 #include <util.h>
 #include <utilmoneystr.h>
@@ -123,6 +124,8 @@ bool WalletParameterInteraction()
                         _("This is the minimum transaction fee you pay on every transaction."));
         CWallet::minTxFee = CFeeRate(n);
     }
+
+    g_wallet_allow_fallback_fee = Params().IsFallbackFeeEnabled();
     if (gArgs.IsArgSet("-fallbackfee"))
     {
         CAmount nFeePerK = 0;
@@ -132,6 +135,7 @@ bool WalletParameterInteraction()
             InitWarning(AmountHighWarn("-fallbackfee") + " " +
                         _("This is the transaction fee you may pay when fee estimates are not available."));
         CWallet::fallbackFee = CFeeRate(nFeePerK);
+        g_wallet_allow_fallback_fee = nFeePerK != 0; //disable fallback fee in case value was set to 0, enable if non-null value
     }
     if (gArgs.IsArgSet("-discardfee"))
     {
diff --git a/src/wallet/test/wallet_test_fixture.cpp b/src/wallet/test/wallet_test_fixture.cpp
index 7797f85f07..6ec5ca29ad 100644
--- a/src/wallet/test/wallet_test_fixture.cpp
+++ b/src/wallet/test/wallet_test_fixture.cpp
@@ -11,6 +11,7 @@ WalletTestingSetup::WalletTestingSetup(const std::string& chainName):
     TestingSetup(chainName)
 {
     bitdb.MakeMock();
+    g_wallet_allow_fallback_fee = true;
 
     bool fFirstRun;
     g_address_type = OUTPUT_TYPE_DEFAULT;
diff --git a/src/wallet/wallet.cpp b/src/wallet/wallet.cpp
index b35f8c7f2b..af07be311e 100644
--- a/src/wallet/wallet.cpp
+++ b/src/wallet/wallet.cpp
@@ -43,6 +43,7 @@ bool bSpendZeroConfChange = DEFAULT_SPEND_ZEROCONF_CHANGE;
 bool fWalletRbf = DEFAULT_WALLET_RBF;
 OutputType g_address_type = OUTPUT_TYPE_NONE;
 OutputType g_change_type = OUTPUT_TYPE_NONE;
+bool g_wallet_allow_fallback_fee = false; //<! will be defined via chainparams
 
 const char * DEFAULT_WALLET_DAT = "wallet.dat";
 const uint32_t BIP32_HARDENED_KEY_LIMIT = 0x80000000;
@@ -2918,6 +2919,11 @@ bool CWallet::CreateTransaction(const std::vector<CRecipient>& vecSend, CWalletT
                 }
 
                 nFeeNeeded = GetMinimumFee(nBytes, coin_control, ::mempool, ::feeEstimator, &feeCalc);
+                if (feeCalc.reason == FeeReason::FALLBACK && !g_wallet_allow_fallback_fee) {
+                    // eventually allow a fallback fee
+                    strFailReason = _("Fee estimation failed. Fallbackfee is disabled. Wait a few blocks or enable -fallbackfee.");
+                    return false;
+                }
 
                 // If we made it here and we aren't even able to meet the relay fee on the next pass, give up
                 // because we must be at the maximum allowed fee.
diff --git a/src/wallet/wallet.h b/src/wallet/wallet.h
index fefe415bb1..8d4b701872 100644
--- a/src/wallet/wallet.h
+++ b/src/wallet/wallet.h
@@ -39,6 +39,7 @@ extern CFeeRate payTxFee;
 extern unsigned int nTxConfirmTarget;
 extern bool bSpendZeroConfChange;
 extern bool fWalletRbf;
+extern bool g_wallet_allow_fallback_fee;
 
 static const unsigned int DEFAULT_KEYPOOL_SIZE = 1000;
 //! -paytxfee default
@@ -65,6 +66,7 @@ static const unsigned int DEFAULT_TX_CONFIRM_TARGET = 6;
 static const bool DEFAULT_WALLET_RBF = false;
 static const bool DEFAULT_WALLETBROADCAST = true;
 static const bool DEFAULT_DISABLE_WALLET = false;
+static const bool DEFAULT_WALLET_ALLOW_FALLBACKFEE = true;
 
 extern const char * DEFAULT_WALLET_DAT;