257 lines
7.8 KiB
C#
257 lines
7.8 KiB
C#
/*
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Copyright (C) 2011-2013 de4dot@gmail.com
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This file is part of de4dot.
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de4dot is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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de4dot is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with de4dot. If not, see <http://www.gnu.org/licenses/>.
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*/
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using System;
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using System.Collections.Generic;
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using System.IO;
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using SevenZip.Compression.LZMA;
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using dnlib.IO;
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using dnlib.DotNet;
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using dnlib.DotNet.Emit;
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using de4dot.blocks;
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namespace de4dot.code.deobfuscators.Confuser {
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static class ConfuserUtils {
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public static int FindCallMethod(IList<Instruction> instrs, int index, Code callCode, string methodFullName) {
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for (int i = index; i < instrs.Count; i++) {
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if (!IsCallMethod(instrs[i], callCode, methodFullName))
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continue;
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return i;
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}
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return -1;
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}
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public static int FindCallMethod(IList<Instr> instrs, int index, Code callCode, string methodFullName) {
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for (int i = index; i < instrs.Count; i++) {
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if (!IsCallMethod(instrs[i].Instruction, callCode, methodFullName))
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continue;
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return i;
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}
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return -1;
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}
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public static bool IsCallMethod(Instruction instr, Code callCode, string methodFullName) {
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if (instr.OpCode.Code != callCode)
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return false;
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var calledMethod = instr.Operand as IMethod;
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return calledMethod != null && calledMethod.FullName == methodFullName;
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}
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public static bool RemoveResourceHookCode(Blocks blocks, MethodDef handler) {
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return RemoveResolveHandlerCode(blocks, handler, "System.Void System.AppDomain::add_ResourceResolve(System.ResolveEventHandler)");
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}
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public static bool RemoveAssemblyHookCode(Blocks blocks, MethodDef handler) {
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return RemoveResolveHandlerCode(blocks, handler, "System.Void System.AppDomain::add_AssemblyResolve(System.ResolveEventHandler)");
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}
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static bool RemoveResolveHandlerCode(Blocks blocks, MethodDef handler, string installHandlerMethod) {
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bool modified = false;
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foreach (var block in blocks.MethodBlocks.GetAllBlocks()) {
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var instrs = block.Instructions;
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for (int i = 0; i < instrs.Count - 4; i++) {
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var call = instrs[i];
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if (call.OpCode.Code != Code.Call)
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continue;
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var calledMethod = call.Operand as IMethod;
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if (calledMethod == null || calledMethod.FullName != "System.AppDomain System.AppDomain::get_CurrentDomain()")
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continue;
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if (instrs[i + 1].OpCode.Code != Code.Ldnull)
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continue;
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var ldftn = instrs[i + 2];
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if (ldftn.OpCode.Code != Code.Ldftn)
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continue;
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if (ldftn.Operand != handler)
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continue;
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var newobj = instrs[i + 3];
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if (newobj.OpCode.Code != Code.Newobj)
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continue;
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var ctor = newobj.Operand as IMethod;
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if (ctor == null || ctor.FullName != "System.Void System.ResolveEventHandler::.ctor(System.Object,System.IntPtr)")
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continue;
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var callvirt = instrs[i + 4];
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if (callvirt.OpCode.Code != Code.Callvirt)
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continue;
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calledMethod = callvirt.Operand as IMethod;
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if (calledMethod == null || calledMethod.FullName != installHandlerMethod)
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continue;
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block.Remove(i, 5);
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modified = true;
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}
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}
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return modified;
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}
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public static byte[] DecryptCompressedInt32Data(Arg64ConstantsReader constReader, int exprStart, int exprEnd, IBinaryReader reader, byte[] decrypted) {
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for (int i = 0; i < decrypted.Length; i++) {
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constReader.Arg = reader.Read7BitEncodedInt32();
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int index = exprStart;
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long result;
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if (!constReader.GetInt64(ref index, out result) || index != exprEnd)
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throw new ApplicationException("Could not decrypt integer");
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decrypted[i] = (byte)result;
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}
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return decrypted;
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}
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static readonly byte[] defaultDecryptKey = new byte[1];
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public static byte[] Decrypt(uint seed, byte[] encrypted) {
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return Decrypt(seed, encrypted, defaultDecryptKey);
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}
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public static byte[] Decrypt(uint seed, byte[] encrypted, byte[] key) {
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var decrypted = new byte[encrypted.Length];
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ushort _m = (ushort)(seed >> 16);
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ushort _c = (ushort)seed;
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ushort m = _c; ushort c = _m;
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for (int i = 0; i < decrypted.Length; i++) {
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decrypted[i] = (byte)(encrypted[i] ^ (seed * m + c) ^ key[i % key.Length]);
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m = (ushort)(seed * m + _m);
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c = (ushort)(seed * c + _c);
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}
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return decrypted;
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}
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public static int CountCalls(MethodDef method, string methodFullName) {
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if (method == null || method.Body == null)
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return 0;
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int count = 0;
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foreach (var instr in method.Body.Instructions) {
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if (instr.OpCode.Code != Code.Call && instr.OpCode.Code != Code.Callvirt && instr.OpCode.Code != Code.Newobj)
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continue;
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var calledMethod = instr.Operand as IMethod;
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if (calledMethod != null && calledMethod.FullName == methodFullName)
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count++;
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}
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return count;
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}
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public static int CountCalls(MethodDef method, MethodDef calledMethod) {
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if (method == null || method.Body == null)
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return 0;
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int count = 0;
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foreach (var instr in method.Body.Instructions) {
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if (instr.OpCode.Code != Code.Call && instr.OpCode.Code != Code.Callvirt && instr.OpCode.Code != Code.Newobj)
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continue;
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if (instr.Operand == calledMethod)
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count++;
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}
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return count;
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}
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public static int CountOpCode(MethodDef method, Code code) {
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if (method == null || method.Body == null)
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return 0;
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int count = 0;
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foreach (var instr in method.Body.Instructions) {
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if (instr.OpCode.Code == code)
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count++;
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}
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return count;
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}
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public static byte[] SevenZipDecompress(byte[] data) {
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var reader = new BinaryReader(new MemoryStream(data));
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var props = reader.ReadBytes(5);
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var decoder = new Decoder();
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decoder.SetDecoderProperties(props);
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long totalSize = reader.ReadInt64();
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long compressedSize = data.Length - props.Length - 8;
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var decompressed = new byte[totalSize];
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decoder.Code(reader.BaseStream, new MemoryStream(decompressed, true), compressedSize, totalSize, null);
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return decompressed;
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}
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// Finds the Lzma type by finding an instruction that allocates a new Lzma.Decoder
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public static TypeDef FindLzmaType(MethodDef method) {
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if (method == null || method.Body == null)
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return null;
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foreach (var instr in method.Body.Instructions) {
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if (instr.OpCode.Code != Code.Newobj)
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continue;
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var ctor = instr.Operand as MethodDef;
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if (ctor == null)
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continue;
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var ctorType = ctor.DeclaringType;
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if (ctorType == null)
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continue;
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if (!IsLzmaType(ctorType.DeclaringType))
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continue;
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return ctorType.DeclaringType;
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}
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return null;
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}
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static bool IsLzmaType(TypeDef type) {
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if (type == null)
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return false;
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if (type.NestedTypes.Count != 6)
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return false;
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if (!CheckLzmaMethods(type))
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return false;
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if (FindLzmaOutWindowType(type.NestedTypes) == null)
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return false;
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return true;
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}
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static bool CheckLzmaMethods(TypeDef type) {
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int methods = 0;
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foreach (var m in type.Methods) {
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if (m.IsStaticConstructor)
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continue;
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if (m.IsInstanceConstructor) {
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if (m.MethodSig.GetParamCount() != 0)
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return false;
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continue;
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}
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if (!DotNetUtils.IsMethod(m, "System.UInt32", "(System.UInt32)"))
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return false;
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methods++;
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}
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return methods == 1;
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}
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static readonly string[] outWindowFields = new string[] {
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"System.Byte[]",
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"System.UInt32",
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"System.IO.Stream",
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};
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static TypeDef FindLzmaOutWindowType(IEnumerable<TypeDef> types) {
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foreach (var type in types) {
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if (new FieldTypes(type).Exactly(outWindowFields))
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return type;
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}
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return null;
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}
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}
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}
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