[wallet] Add high transaction fee warnings

src/init.cpp

@@ -951,10 +951,10 @@ bool AppInit2(boost::thread_group& threadGroup, CScheduler& scheduler)
     if (mapArgs.count("-minrelaytxfee"))
     {
         CAmount n = 0;
-        if (ParseMoney(mapArgs["-minrelaytxfee"], n) && n > 0)
-            ::minRelayTxFee = CFeeRate(n);
-        else
+        if (!ParseMoney(mapArgs["-minrelaytxfee"], n))
             return InitError(AmountErrMsg("minrelaytxfee", mapArgs["-minrelaytxfee"]));
+        // High fee check is done afterward in CWallet::ParameterInteraction()
+        ::minRelayTxFee = CFeeRate(n);
     }
 
     fRequireStandard = !GetBoolArg("-acceptnonstdtxn", !Params().RequireStandard());

src/ui_interface.cpp

@@ -18,6 +18,11 @@ void InitWarning(const std::string& str)
     uiInterface.ThreadSafeMessageBox(str, "", CClientUIInterface::MSG_WARNING);
 }
 
+std::string AmountHighWarn(const std::string& optname)
+{
+    return strprintf(_("%s is set very high!"), optname);
+}
+
 std::string AmountErrMsg(const char* const optname, const std::string& strValue)
 {
     return strprintf(_("Invalid amount for -%s=<amount>: '%s'"), optname, strValue);

src/ui_interface.h

@@ -112,6 +112,8 @@ void InitWarning(const std::string& str);
 /** Show error message **/
 bool InitError(const std::string& str);
 
+std::string AmountHighWarn(const std::string& optname);
+
 std::string AmountErrMsg(const char* const optname, const std::string& strValue);
 
 extern CClientUIInterface uiInterface;

src/wallet/wallet.cpp

@@ -3485,13 +3485,19 @@ bool CWallet::ParameterInteraction()
     if (GetArg("-prune", 0) && GetBoolArg("-rescan", false))
         return InitError(_("Rescans are not possible in pruned mode. You will need to use -reindex which will download the whole blockchain again."));
 
+    if (::minRelayTxFee.GetFeePerK() > HIGH_TX_FEE_PER_KB)
+        InitWarning(AmountHighWarn("-minrelaytxfee") + " " +
+                    _("The wallet will avoid paying less than the minimum relay fee."));
+
     if (mapArgs.count("-mintxfee"))
     {
         CAmount n = 0;
-        if (ParseMoney(mapArgs["-mintxfee"], n) && n > 0)
-            CWallet::minTxFee = CFeeRate(n);
-        else
+        if (!ParseMoney(mapArgs["-mintxfee"], n))
             return InitError(AmountErrMsg("mintxfee", mapArgs["-mintxfee"]));
+        if (n > HIGH_TX_FEE_PER_KB)
+            InitWarning(AmountHighWarn("-mintxfee") + " " +
+                        _("This is the minimum transaction fee you pay on every transaction."));
+        CWallet::minTxFee = CFeeRate(n);
     }
     if (mapArgs.count("-fallbackfee"))
     {
@@ -3499,7 +3505,8 @@ bool CWallet::ParameterInteraction()
         if (!ParseMoney(mapArgs["-fallbackfee"], nFeePerK))
             return InitError(strprintf(_("Invalid amount for -fallbackfee=<amount>: '%s'"), mapArgs["-fallbackfee"]));
         if (nFeePerK > HIGH_TX_FEE_PER_KB)
-            InitWarning(_("-fallbackfee is set very high! This is the transaction fee you may pay when fee estimates are not available."));
+            InitWarning(AmountHighWarn("-fallbackfee") + " " +
+                        _("This is the transaction fee you may pay when fee estimates are not available."));
         CWallet::fallbackFee = CFeeRate(nFeePerK);
     }
     if (mapArgs.count("-paytxfee"))
@@ -3508,7 +3515,9 @@ bool CWallet::ParameterInteraction()
         if (!ParseMoney(mapArgs["-paytxfee"], nFeePerK))
             return InitError(AmountErrMsg("paytxfee", mapArgs["-paytxfee"]));
         if (nFeePerK > HIGH_TX_FEE_PER_KB)
-            InitWarning(_("-paytxfee is set very high! This is the transaction fee you will pay if you send a transaction."));
+            InitWarning(AmountHighWarn("-paytxfee") + " " +
+                        _("This is the transaction fee you will pay if you send a transaction."));
+
         payTxFee = CFeeRate(nFeePerK, 1000);
         if (payTxFee < ::minRelayTxFee)
         {