Add Max_Fee as the optional for gas limit.

RpcWallet/RpcWallet.cs

@@ -21,6 +21,7 @@ public class RpcWallet : Plugin, IRpcPlugin
 
         public override void Configure()
         {
+            Settings.Load(GetConfiguration());
         }
 
         public void PreProcess(HttpContext context, string method, JArray _params)
@@ -309,7 +310,7 @@ private JObject SendFrom(UIntBase assetId, UInt160 from, UInt160 to, string valu
             }, from: from, change_address: change_address, fee: fee);
             if (tx.Size > 1024)
             {
-                fee += Fixed8.FromDecimal(tx.Size * 0.00001m + 0.001m);
+                fee = Fixed8.Max(Fixed8.FromDecimal(tx.Size * 0.00001m + 0.001m), fee);
                 tx = Wallet.MakeTransaction(null, new[]
                 {
                     new TransferOutput
@@ -322,6 +323,8 @@ private JObject SendFrom(UIntBase assetId, UInt160 from, UInt160 to, string valu
             }
             if (tx == null)
                 throw new RpcException(-300, "Insufficient funds");
+            if (fee > Settings.Default.MaxFee)
+                throw new RpcException(-301, "The necessary fee is more than the Max_fee, this transaction is failed. Please increase your Max_fee value.");
             return SignAndRelay(tx);
         }
 
@@ -349,11 +352,13 @@ private JObject SendMany(UInt160 from, JArray to, Fixed8 fee, UInt160 change_add
             Transaction tx = Wallet.MakeTransaction(null, outputs, from: from, change_address: change_address, fee: fee);
             if (tx.Size > 1024)
             {
-                fee += Fixed8.FromDecimal(tx.Size * 0.00001m + 0.001m);
+                fee = Fixed8.Max(Fixed8.FromDecimal(tx.Size * 0.00001m + 0.001m), fee);
                 tx = Wallet.MakeTransaction(null, outputs, from: from, change_address: change_address, fee: fee);
             }
             if (tx == null)
                 throw new RpcException(-300, "Insufficient funds");
+            if (fee > Settings.Default.MaxFee)
+                throw new RpcException(-301, "The necessary fee is more than the Max_fee, this transaction is failed. Please increase your Max_fee value.");
             return SignAndRelay(tx);
         }
 
@@ -377,7 +382,7 @@ private JObject SendToAddress(UIntBase assetId, UInt160 scriptHash, string value
             }, change_address: change_address, fee: fee);
             if (tx.Size > 1024)
             {
-                fee += Fixed8.FromDecimal(tx.Size * 0.00001m + 0.001m);
+                fee = Fixed8.Max(Fixed8.FromDecimal(tx.Size * 0.00001m + 0.001m), fee);
                 tx = Wallet.MakeTransaction(null, new[]
                 {
                     new TransferOutput
@@ -390,6 +395,8 @@ private JObject SendToAddress(UIntBase assetId, UInt160 scriptHash, string value
             }
             if (tx == null)
                 throw new RpcException(-300, "Insufficient funds");
+            if (fee > Settings.Default.MaxFee)
+                throw new RpcException(-301, "The necessary fee is more than the Max_fee, this transaction is failed. Please increase your Max_fee value.");
             return SignAndRelay(tx);
         }
     }

RpcWallet/RpcWallet.csproj

@@ -5,6 +5,13 @@
     <TargetFramework>netstandard2.0</TargetFramework>
     <RootNamespace>Neo.Plugins</RootNamespace>
   </PropertyGroup>
+
+  <ItemGroup>
+    <None Update="RpcWallet\config.json">
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+      <CopyToPublishDirectory>PreserveNewest</CopyToPublishDirectory>
+    </None>
+  </ItemGroup>
 
   <ItemGroup>
     <PackageReference Include="Neo" Version="2.10.0" />

RpcWallet/RpcWallet/config.json

@@ -0,0 +1,5 @@
+{
+  "PluginConfiguration": {
+    "MaxFee": 0.1
+  }
+}

RpcWallet/Settings.cs

@@ -0,0 +1,21 @@
+using Microsoft.Extensions.Configuration;
+
+namespace Neo.Plugins
+{
+    internal class Settings
+    {
+        public Fixed8 MaxFee { get; }
+
+        public static Settings Default { get; private set; }
+
+        private Settings(IConfigurationSection section)
+        {
+            this.MaxFee = Fixed8.Parse(section.GetValue("MaxFee", "0.1"));
+        }
+
+        public static void Load(IConfigurationSection section)
+        {
+            Default = new Settings(section);
+        }
+    }
+}