Drop ancient zlib dependency in favor of native .NET library calls.

Due to different naming of those compression libraries per OS there is a custom dll import resolver used.

WowPacketParser/Misc/FlushCode.cs

@@ -0,0 +1,10 @@
+namespace WowPacketParser.Misc
+{
+    public enum FlushCode
+    {
+        NoFlush   = 0,
+        SyncFlush = 2,
+        Finish    = 4,
+        Block     = 5
+    }
+}

WowPacketParser/Misc/Packet.cs

@@ -1,9 +1,9 @@
 using Google.Protobuf.WellKnownTypes;
-using Ionic.Zlib;
 using System;
 using System.Diagnostics.CodeAnalysis;
 using System.IO;
 using System.Net;
+using System.Runtime.InteropServices;
 using System.Text;
 using WowPacketParser.Enums;
 using WowPacketParser.Enums.Version;
@@ -95,26 +95,7 @@ public void AddSniffData(StoreNameType type, int id, string data)
             Storage.SniffData.Add(item, TimeSpan);
         }
 
-        public bool TryInflate(int inflatedSize, int index, byte[] arr, ref byte[] newarr)
-        {
-            try
-            {
-                if (!SessionHandler.ZStreams.ContainsKey(index))
-                    SessionHandler.ZStreams[index] = new ZlibCodec(CompressionMode.Decompress);
-                SessionHandler.ZStreams[index].InputBuffer = arr;
-                SessionHandler.ZStreams[index].NextIn = 0;
-                SessionHandler.ZStreams[index].AvailableBytesIn = arr.Length;
-                SessionHandler.ZStreams[index].OutputBuffer = newarr;
-                SessionHandler.ZStreams[index].NextOut = 0;
-                SessionHandler.ZStreams[index].AvailableBytesOut = inflatedSize;
-                SessionHandler.ZStreams[index].Inflate(FlushType.Sync);
-                return true;
-            }
-            catch (ZlibException)
-            {
-                return false;
-            }
-        }
+        public void ResetInflateStream() => ZLibHelper.ResetInflateStream(ConnectionIndex);
 
         public Packet Inflate(int inflatedSize, bool keepStream = true)
         {
@@ -127,36 +108,12 @@ public Packet Inflate(int inflatedSize, bool keepStream = true)
             if (keepStream)
             {
                 int idx = ConnectionIndex;
-                while (!TryInflate(inflatedSize, idx, arr, ref newarr) && idx <= 4)
+                while (!ZLibHelper.TryInflate(inflatedSize, idx, arr, ref newarr) && idx <= 4)
                     idx += 1;
             }
             else
             {
-                /*try
-                {
-                    var inflater = new Inflater(true);
-                    inflater.SetInput(arr, 0, arr.Length);
-                    inflater.Inflate(newarr, 0, inflatedSize);
-                }
-                catch (ICSharpCode.SharpZipLib.SharpZipBaseException)
-                {
-                    var inflater = new Inflater(true);
-                    inflater.SetInput(arr, 0, arr.Length);
-                    inflater.Inflate(newarr, 0, inflatedSize);
-                }*/
-                var stream = new ZlibCodec(CompressionMode.Decompress)
-                {
-                    InputBuffer = arr,
-                    NextIn = 0,
-                    AvailableBytesIn = arr.Length,
-                    OutputBuffer = newarr,
-                    NextOut = 0,
-                    AvailableBytesOut = inflatedSize
-                };
-
-                stream.Inflate(FlushType.None);
-                stream.Inflate(FlushType.Finish);
-                stream.EndInflate();
+                ZLibHelper.Inflate(inflatedSize, arr, newarr);
             }
 
             // Cannot use "using" here
@@ -178,35 +135,12 @@ public Packet Inflate(int arrSize, int inflatedSize, bool keepStream = true)
             if (keepStream)
             {
                 int idx = ConnectionIndex;
-                while (!TryInflate(inflatedSize, idx, arr, ref newarr) && idx <= 4)
+                while (!ZLibHelper.TryInflate(inflatedSize, idx, arr, ref newarr) && idx <= 4)
                     idx += 1;
             }
             else
             {
-                /*try
-                {
-                    var inflater = new Inflater(true);
-                    inflater.SetInput(arr, 0, arr.Length);
-                    inflater.Inflate(newarr, 0, inflatedSize);
-                }
-                catch (ICSharpCode.SharpZipLib.SharpZipBaseException)
-                {
-                    var inflater = new Inflater(true);
-                    inflater.SetInput(arr, 0, arr.Length);
-                    inflater.Inflate(newarr, 0, inflatedSize);
-                }*/
-                var stream = new ZlibCodec(CompressionMode.Decompress)
-                {
-                    InputBuffer = arr,
-                    NextIn = 0,
-                    AvailableBytesIn = arr.Length,
-                    OutputBuffer = newarr,
-                    NextOut = 0,
-                    AvailableBytesOut = inflatedSize
-                };
-                stream.Inflate(FlushType.None);
-                stream.Inflate(FlushType.Finish);
-                stream.EndInflate();
+                ZLibHelper.Inflate(inflatedSize, arr, newarr);
             }
 
             // Cannot use "using" here

WowPacketParser/Misc/ZLibHelper.cs

@@ -0,0 +1,92 @@
+using System;
+using System.Runtime.InteropServices;
+using WowPacketParser.Parsing.Parsers;
+
+namespace WowPacketParser.Misc
+{
+    internal partial class ZLibHelper
+    {
+        private const string CompressionLib = "compression_native";
+
+        [LibraryImport(CompressionLib, EntryPoint = "CompressionNative_InflateInit2_")]
+        private static partial int InflateInit2(ref ZStream zStream, int windowBits);
+
+        [LibraryImport(CompressionLib, EntryPoint = "CompressionNative_Inflate")]
+        private static partial int Inflate(ref ZStream zStream, FlushCode flush);
+
+        [LibraryImport(CompressionLib, EntryPoint = "CompressionNative_InflateEnd")]
+        private static partial int InflateEnd(ref ZStream zStream);
+
+        public static void ResetInflateStream(int connectionIndex)
+        {
+            ref var zStream = ref CollectionsMarshal.GetValueRefOrAddDefault(SessionHandler.ZStreams, connectionIndex, out bool exists);
+
+            InflateInit2(ref zStream, 15);
+        }
+
+        public static bool TryInflate(int inflatedSize, int index, byte[] arr, ref byte[] newarr)
+        {
+            try
+            {
+                ref var zStream = ref CollectionsMarshal.GetValueRefOrAddDefault(SessionHandler.ZStreams, index, out bool exists);
+
+                if (!exists)
+                {
+                    var initResult = InflateInit2(ref zStream, 15);
+
+                    if (initResult != 0)
+                        return false;
+                }
+
+                nint uncompressedDataPtr = Marshal.AllocHGlobal(inflatedSize);
+                nint compressedDataPtr = Marshal.AllocHGlobal(arr.Length);
+
+                Marshal.Copy(arr, 0, compressedDataPtr, arr.Length);
+
+                zStream.AvailIn = (uint)arr.Length;
+                zStream.NextIn = compressedDataPtr;
+                zStream.AvailOut = (uint)inflatedSize;
+                zStream.NextOut = uncompressedDataPtr;
+
+                Inflate(ref zStream, FlushCode.SyncFlush);
+
+                Marshal.Copy(uncompressedDataPtr, newarr, 0, inflatedSize);
+
+                Marshal.FreeHGlobal(compressedDataPtr);
+                Marshal.FreeHGlobal(uncompressedDataPtr);
+
+                return true;
+            }
+            catch (Exception)
+            {
+                return false;
+            }
+        }
+
+        public static void Inflate(int inflatedSize, byte[] arr, byte[] newarr)
+        {
+            ZStream zStream = default;
+
+            InflateInit2(ref zStream, 15);
+
+            nint uncompressedDataPtr = Marshal.AllocHGlobal(inflatedSize);
+            nint compressedDataPtr = Marshal.AllocHGlobal(arr.Length);
+
+            Marshal.Copy(arr, 0, compressedDataPtr, arr.Length);
+
+            zStream.AvailIn = (uint)arr.Length;
+            zStream.NextIn = compressedDataPtr;
+            zStream.AvailOut = (uint)inflatedSize;
+            zStream.NextOut = uncompressedDataPtr;
+
+            Inflate(ref zStream, FlushCode.NoFlush);
+            Inflate(ref zStream, FlushCode.Finish);
+            InflateEnd(ref zStream);
+
+            Marshal.Copy(uncompressedDataPtr, newarr, 0, inflatedSize);
+
+            Marshal.FreeHGlobal(compressedDataPtr);
+            Marshal.FreeHGlobal(uncompressedDataPtr);
+        }
+    }
+}

WowPacketParser/Misc/ZStream.cs

@@ -0,0 +1,17 @@
+using System.Runtime.InteropServices;
+
+namespace WowPacketParser.Misc
+{
+    [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)]
+    public struct ZStream
+    {
+        internal nint NextIn;
+        internal nint NextOut;
+        internal nint Msg;
+
+        readonly nint InternalState;
+
+        internal uint AvailIn;
+        internal uint AvailOut;
+    }
+}

WowPacketParser/Parsing/Parsers/SessionHandler.cs

@@ -1,4 +1,3 @@
-using Ionic.Zlib;
 using System;
 using System.Collections.Generic;
 using System.Text;
@@ -10,7 +9,7 @@ namespace WowPacketParser.Parsing.Parsers
     public static class SessionHandler
     {
         public static WowGuid LoginGuid;
-        public static Dictionary<int, ZlibCodec> ZStreams = new Dictionary<int, ZlibCodec>();
+        public static Dictionary<int, ZStream> ZStreams = new Dictionary<int, ZStream>();
 
         [Parser(Opcode.SMSG_AUTH_CHALLENGE, ClientVersionBuild.Zero, ClientVersionBuild.V4_0_1a_13205)]
         public static void HandleServerAuthChallenge(Packet packet)
@@ -559,7 +558,7 @@ public static void HandleMessageOfTheDay(Packet packet)
         public static void HandleResetCompressionContext(Packet packet)
         {
             packet.ReadInt32("Unk?");
-            ZStreams[packet.ConnectionIndex] = new ZlibCodec(CompressionMode.Decompress);
+            packet.ResetInflateStream();
         }
     }
 }

WowPacketParser/Program.cs

@@ -3,6 +3,8 @@
 using System.Globalization;
 using System.IO;
 using System.Linq;
+using System.Reflection;
+using System.Runtime.InteropServices;
 using System.Threading;
 using WowPacketParser.Loading;
 using WowPacketParser.Misc;
@@ -15,6 +17,23 @@ public static class Program
     {
         private static void Main(string[] args)
         {
+            NativeLibrary.SetDllImportResolver(Assembly.GetExecutingAssembly(), (libraryName, assembly, searchPath) =>
+            {
+                if (libraryName.Equals("compression_native", StringComparison.OrdinalIgnoreCase))
+                {
+                    if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
+                        return NativeLibrary.Load("System.IO.Compression.Native.dll", assembly, searchPath);
+
+                    if (RuntimeInformation.IsOSPlatform(OSPlatform.OSX))
+                        return NativeLibrary.Load("libSystem.IO.Compression.Native.dylib", assembly, searchPath);
+
+                    if (RuntimeInformation.IsOSPlatform(OSPlatform.Linux))
+                        return NativeLibrary.Load("libSystem.IO.Compression.Native.so", assembly, searchPath);
+                }
+
+                return default;
+            });
+
             SetUpWindowTitle();
             SetUpConsole();
 

WowPacketParser/WowPacketParser.csproj

@@ -5,7 +5,6 @@
     </PropertyGroup>
 
     <ItemGroup>
-        <PackageReference Include="Iconic.Zlib.Netstandard" Version="1.0.0" />
         <PackageReference Include="MySql.Data" Version="8.3.0" />
         <PackageReference Include="RawScape.Wintellect.PowerCollections" Version="1.0.1" />
         <PackageReference Include="Sigil" Version="5.0.0" />