fix delimiter of framedelimiter

Author: erwan-joly

src/NosCore.Networking/Encoding/FrameDelimiter.cs

@@ -5,6 +5,7 @@
 // -----------------------------------
 
 using System.Collections.Generic;
+using System.Linq;
 using DotNetty.Buffers;
 using DotNetty.Codecs;
 using DotNetty.Transport.Channels;
@@ -15,20 +16,18 @@ namespace NosCore.Networking.Encoding;
 public class FrameDelimiter : ByteToMessageDecoder
 {
     private readonly ISessionRefHolder _sessionRefHolder;
-    private readonly IPipelineConfiguration _pipelineConfiguration;
-
-    public FrameDelimiter(ISessionRefHolder sessionRefHolder, IPipelineConfiguration pipelineConfiguration)
+    public FrameDelimiter(ISessionRefHolder sessionRefHolder)
     {
         _sessionRefHolder = sessionRefHolder;
-        _pipelineConfiguration = pipelineConfiguration;
     }
 
+
     protected override void Decode(IChannelHandlerContext context, IByteBuffer input, List<object> output)
     {
         var sessionId = context.Channel.Id.AsLongText();
         var mapper = _sessionRefHolder[sessionId];
 
-        var currentDelimiter = mapper.SessionId == 0 ? (byte)0xE : unchecked((byte)((_pipelineConfiguration.Delimiter ?? 0) + mapper.SessionId));
+        var currentDelimiter = GetDelimiter(mapper.SessionId, mapper.SessionId == 0);
 
         var startReaderIndex = input.ReaderIndex;
         var endReaderIndex = startReaderIndex + input.ReadableBytes;
@@ -45,4 +44,20 @@ protected override void Decode(IChannelHandlerContext context, IByteBuffer input
             }
         }
     }
+
+    public static byte GetDelimiter(int session, bool isFirstPacket = false)
+    {
+        int stype = !isFirstPacket ? (session >> 6) & 3 : -1;
+
+        var key = session & 0xFF;
+
+        return (byte)(stype switch
+        {
+            0 => (0xff + key + 0x40) & 0xFF,
+            1 => (0xff - key - 0x40) & 0xFF,
+            2 => ((0xff ^ 0xC3) + key + 0x40) & 0xFF,
+            3 => ((0xff ^ 0xC3) - key - 0x40) & 0xFF,
+            _ => (0xff + 0xF) & 0xFF
+        });
+    }
 }

src/NosCore.Networking/IPipelineConfiguration.cs

@@ -8,5 +8,5 @@ namespace NosCore.Networking;
 
 public interface IPipelineConfiguration
 {
-    public byte? Delimiter { get; set; }
+    public bool UseDelimiter { get; set; }
 }

src/NosCore.Networking/NosCore.Networking.csproj

@@ -12,7 +12,7 @@
 		<RepositoryUrl>https://github.com/NosCoreIO/NosCore.Networking.git</RepositoryUrl>
 		<PackageIconUrl></PackageIconUrl>
 		<PackageTags>nostale, noscore, nostale private server source, nostale emulator</PackageTags>
-		<Version>5.0.0</Version>
+		<Version>6.0.0</Version>
 		<PackageRequireLicenseAcceptance>false</PackageRequireLicenseAcceptance>
 		<Description>NosCore Networking</Description>
 		<PackageLicenseExpression>MIT</PackageLicenseExpression>

src/NosCore.Networking/PipelineFactory.cs

@@ -52,10 +52,9 @@ public void CreatePipeline()
                 pipeline.AddLast(filter);
             }
 
-            if (_pipelineConfiguration.Delimiter != null)
+            if (_pipelineConfiguration.UseDelimiter)
             {
-
-                pipeline.AddLast(new FrameDelimiter(_sessionRefHolder, _pipelineConfiguration));
+                pipeline.AddLast(new FrameDelimiter(_sessionRefHolder));
             }
 
             pipeline.AddLast(_decoder);