113 lines
4.6 KiB
C#
113 lines
4.6 KiB
C#
using dnlib.DotNet;
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using dnlib.DotNet.Emit;
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using dnlib.DotNet.PolymorphicWriter.Utilities;
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using Obfuz.Settings;
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using Obfuz.Utils;
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using System;
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using System.Linq;
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using System.Reflection;
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using System.Runtime.CompilerServices;
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using UnityEngine;
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using FieldAttributes = dnlib.DotNet.FieldAttributes;
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using KeyGenerator = Obfuz.Utils.KeyGenerator;
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using TypeAttributes = dnlib.DotNet.TypeAttributes;
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namespace Obfuz.ObfusPasses.Watermark
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{
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public class WatermarkPass : ObfuscationPassBase
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{
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private readonly WatermarkSettingsFacade _watermarkSettings;
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public WatermarkPass(WatermarkSettingsFacade watermarkSettingsFacade)
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{
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this._watermarkSettings = watermarkSettingsFacade;
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}
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public override ObfuscationPassType Type => ObfuscationPassType.WaterMark;
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public override void Start()
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{
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}
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public override void Stop()
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{
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}
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public override void Process()
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{
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var ctx = ObfuscationPassContext.Current;
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foreach (ModuleDef mod in ctx.modulesToObfuscate)
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{
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AddWaterMarkToAssembly(mod, _watermarkSettings.text);
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}
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}
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private TypeDef GetDataHolderType(ModuleDef module, TypeDef declaringType, int size)
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{
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using (var scope = new DisableTypeDefFindCacheScope(module))
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{
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var dataHolderType = new TypeDefUser($"$Obfuz$WatermarkDataHolderSize{size}_{declaringType.NestedTypes.Count}", module.Import(typeof(System.ValueType)));
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dataHolderType.Attributes = TypeAttributes.NestedPrivate | TypeAttributes.Sealed;
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dataHolderType.Layout = TypeAttributes.ExplicitLayout;
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dataHolderType.PackingSize = 1;
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dataHolderType.ClassSize = (uint)size;
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dataHolderType.DeclaringType = declaringType;
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return dataHolderType;
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}
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}
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private void AddWaterMarkToAssembly(ModuleDef module, string waterMarkText)
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{
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string finalWatermarkText = $"{waterMarkText} [{module.Name}]";
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TypeDef moduleType = module.FindNormal("<PrivateImplementationDetails>");
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if (moduleType == null)
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{
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//throw new Exception($"Module '{module.Name}' does not contain a '<PrivateImplementationDetails>' type.");
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moduleType = new TypeDefUser("<PrivateImplementationDetails>", module.Import(typeof(object)));
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moduleType.Attributes = TypeAttributes.NotPublic | TypeAttributes.Sealed;
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moduleType.CustomAttributes.Add(new CustomAttribute(module.Import(module.Import(typeof(CompilerGeneratedAttribute)).ResolveTypeDefThrow().FindDefaultConstructor())));
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module.Types.Add(moduleType);
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}
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var ctx = ObfuscationPassContext.Current;
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EncryptionScopeInfo encryptionScope = ctx.moduleEntityManager.EncryptionScopeProvider.GetScope(module);
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var random = encryptionScope.localRandomCreator(0);
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byte[] watermarkBytes = KeyGenerator.GenerateKey(finalWatermarkText, _watermarkSettings.signatureLength);
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for (int subIndex = 0; subIndex < watermarkBytes.Length;)
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{
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int subSegmentLength = Math.Min(random.NextInt(16, 32) & ~3, watermarkBytes.Length - subIndex);
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int paddingLength = random.NextInt(8, 32) & ~3;
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int totalLength = subSegmentLength + paddingLength;
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TypeDef dataHolderType = GetDataHolderType(module, moduleType, totalLength);
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byte[] subSegment = new byte[totalLength];
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Buffer.BlockCopy(watermarkBytes, subIndex, subSegment, 0, subSegmentLength);
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for (int i = subSegmentLength; i < totalLength; i++)
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{
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subSegment[i] = (byte)random.NextInt(0, 256);
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}
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subIndex += subSegmentLength;
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var field = new FieldDefUser($"$Obfuz$WatermarkDataHolderField{moduleType.Fields.Count}",
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new FieldSig(dataHolderType.ToTypeSig()),
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FieldAttributes.Assembly | FieldAttributes.InitOnly | FieldAttributes.Static | FieldAttributes.HasFieldRVA);
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field.DeclaringType = moduleType;
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field.InitialValue = subSegment;
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}
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var moduleTypeFields = moduleType.Fields.ToList();
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RandomUtil.ShuffleList(moduleTypeFields, random);
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moduleType.Fields.Clear();
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foreach (var field in moduleTypeFields)
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{
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moduleType.Fields.Add(field);
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}
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}
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}
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}
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