fix: 요청 패킷 멀티 쓰기 오류 수정 및 서비스 응답 에러 패킷 응답 추가

Author: LineYK

ModBusSimulatorSlave/Data/RequestPacket.cs

@@ -1,5 +1,11 @@
 namespace ModBusSimSlave.Data
 {
+    /**
+     * Request Packet 요청 패킷
+     * Function Code 15, 16을 제외한 모든 코드에서는 총 8바이트 고정 크기를 가짐
+     * 15, 16 코드에서는 수량과 코일 혹은 레지스터에 따라 Byte Count와 Write Data의 길이가 달라짐
+     * 수량 및 바이트 카운터에 따라 패킷 검수 과정
+     */
     class RequestPacket
     {
         private byte[] _frame;
@@ -38,12 +44,18 @@ private RequestPacket(byte slaveAddr, byte functionCode, byte[] data, byte[] wri
             };
             _multiWirteData = writeData;
 
+            if (_multiWirteData.Length != _byteCount)
+                throw new ArgumentException($"바이트 크기에 맞지 않는 데이터 들어옴\n바이크 크기: {_byteCount}, 들어온 데이터 크기: {_multiWirteData.Length}");
+
             _frame = GetMultiWriteFrame();
             _crc = new byte[2];
             Array.Copy(_frame, _frame.Length - 2, _crc, 0, 2);
 
         }
 
+        /**
+         * 외부에서 받아온 패킷을 가공하기 위한 생성자
+         */
         public RequestPacket(byte[] frame)
         {
             _frame = frame;
@@ -54,7 +66,7 @@ public RequestPacket(byte[] frame)
                 _functionCode = frame[1];
                 _data = frame.Skip(2).Take(4).ToArray();
                 _byteCount = frame[6];
-                _multiWirteData = frame.Skip(6).Take(_byteCount).ToArray();
+                _multiWirteData = frame.Skip(7).Take(_byteCount).ToArray();
                 _crc = new byte[2];
                 Array.Copy(frame, frame.Length - 2, _crc, 0, 2);
             }
@@ -103,6 +115,9 @@ private byte[] GetMultiWriteFrame()
         }
 
 
+        /**
+         * Getter & Setter
+         */
         public byte[] Frame
         {
             get { return _frame; }
@@ -146,6 +161,9 @@ public byte[] Crc
         }
 
 
+        /**
+         * 패킷 빌더
+         */
         public class RequestPacketBuilder
         {
             private byte _slaveAddr;

ModBusSimulatorSlave/SerialPortConnector.cs

@@ -51,16 +51,16 @@ private async void DataReceivedHandler(object sender, SerialDataReceivedEventArg
 
         private void ProcessPacketBuffer(byte[] bytes)
         {
-            lock(packBufferLock)
+            lock (packBufferLock)
             {
                 packetBuffer.AddRange(bytes);
-                while(packetBuffer.Count >= 8)
+                while (packetBuffer.Count >= 8)
                 {
-                    int expectedLength = PacketHelpers.GetExpectedRequestPKLength(packetBuffer.ToArray());
+                    int expectedLength = PacketHelpers.GetExpectedRequestPKLength([.. packetBuffer]);
 
                     if (packetBuffer.Count < expectedLength) break;
 
-                    byte[] packetBytes = packetBuffer.GetRange(0, expectedLength).ToArray();
+                    byte[] packetBytes = [.. packetBuffer.GetRange(0, expectedLength)];
 
                     if (PacketHelpers.CheckCRC(packetBytes))
                     {
@@ -71,25 +71,18 @@ private void ProcessPacketBuffer(byte[] bytes)
                         packet.Data.ToList().ForEach(e => Debug.Write($"{e:X2} "));
                         Debug.WriteLine("");
 
-                        ResponsePacket? response = service.Response(packet);
+                        ResponsePacket response = service.Response(packet);
                         byte[] frame;
 
-                        if (response == null)
-                        {
-                            Debug.WriteLine("응답 데이터 없음");
-                            frame = [1];
-                        }
-                        else
-                        {
-                            frame = response.Frame;
-                            Debug.WriteLine("응답 데이터");
-                            frame.ToList().ForEach(e => Debug.Write($"{e:X2} "));
-                            Debug.WriteLine("");
-                        }
+                        frame = response.Frame;
+                        Debug.WriteLine("응답 데이터");
+                        frame.ToList().ForEach(e => Debug.Write($"{e:X2} "));
+                        Debug.WriteLine("");
 
                         seriallPort.Write(frame, 0, frame.Length);
                         packetBuffer.RemoveRange(0, expectedLength);
-                    } else
+                    }
+                    else
                     {
                         Console.Error.WriteLine("CRC 불일치");
                         packetBuffer.RemoveAt(0);

ModBusSimulatorSlave/Service.cs

@@ -11,9 +11,9 @@ public Service(VirtualDevice device)
             VirtualDevice = device;
         }
 
-        public ResponsePacket? Response(RequestPacket requestPacket)
+        public ResponsePacket Response(RequestPacket requestPacket)
         {
-            if (requestPacket.SlaveAddr != VirtualDevice.SlaveID) return null;
+            if (requestPacket.SlaveAddr != VirtualDevice.SlaveID) return ErrorResponse(0x02, requestPacket);
 
             Console.WriteLine("수신 데이터");
             Console.WriteLine($"SlaveAddr: {requestPacket.SlaveAddr} FunctioanCode: {requestPacket.FunctionCode}");
@@ -33,7 +33,7 @@ public Service(VirtualDevice device)
                 0x06 => WriteSingleRegister(requestPacket),
                 0x0F => WriteMultipleCoils(requestPacket),
                 0x10 => WriteMultipleRegisters(requestPacket),
-                _ => null,
+                _ => ErrorResponse(0x01, requestPacket),
             };
         }
 
@@ -132,6 +132,9 @@ private ResponsePacket WriteSingleCoil(RequestPacket packet)
             ushort address = (ushort)((packet.Data[0] << 8) | packet.Data[1] & 0xFF);
             ushort data = (ushort)((packet.Data[2] << 8) | packet.Data[3] & 0xFF);
 
+            if (data != 0xFF00 && data != 0x0000) 
+                return ErrorResponse(0x03, packet);
+            
             // 0xFF00이면 true, 0x0000이면 false
             VirtualDevice.Coils[address] = data == 0xFF00;
 
@@ -161,8 +164,11 @@ private ResponsePacket WriteMultipleCoils(RequestPacket packet)
         {
             ushort address = (ushort)((packet.Data[0] << 8) | packet.Data[1] & 0xFF);
             ushort quantity = (ushort)((packet.Data[2] << 8) | packet.Data[3] & 0xFF);
-            byte byteCount = packet.Data[4];
-            byte[] writeData = packet.Data.Skip(5).ToArray();
+            byte byteCount = packet.ByteCount;
+            byte[] writeData = packet.MultiWriteData;
+
+            if (byteCount != writeData.Length || VirtualDevice.Coils.Length < quantity) 
+                return ErrorResponse(0x03, packet);
 
             // 쓰기 데이터를 코일에 쓰기
             for (int i = 0; i < quantity; i++)
@@ -187,6 +193,9 @@ private ResponsePacket WriteMultipleRegisters(RequestPacket packet)
             byte byteCount = packet.ByteCount;
             byte[] writeData = packet.MultiWriteData;
 
+            if (byteCount != writeData.Length || VirtualDevice.HoldingRegisters.Length < quantity)
+                return ErrorResponse(0x03, packet);
+
             // 쓰기 데이터를 레지스터에 쓰기
             for (int i = 0; i < quantity; i++)
             {
@@ -201,5 +210,14 @@ private ResponsePacket WriteMultipleRegisters(RequestPacket packet)
                 .Build();
         }
 
+        private ResponsePacket ErrorResponse(byte errorCode, RequestPacket packet)
+        {
+            return new ResponsePacket.ResponsePacketBuilder()
+                .SetSlaveAddr(packet.SlaveAddr)
+                .SetFunctionCode((byte)(packet.FunctionCode | 0x80))
+                .SetData([errorCode])
+                .Build();
+        }
+
     }
 }