context: /*
      Copyright (C) 2011-2015 de4dot@gmail.com
  
      This file is part of de4dot.
  
      de4dot is free software: you can redistribute it and/or modify
      it under the terms of the GNU General Public License as published by
      the Free Software Foundation, either version 3 of the License, or
      (at your option) any later version.
  
      de4dot is distributed in the hope that it will be useful,
      but WITHOUT ANY WARRANTY; without even the implied warranty of
      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      GNU General Public License for more details.
  
      You should have received a copy of the GNU General Public License
      along with de4dot.  If not, see <http://www.gnu.org/licenses/>.
  */
  
  using System;
  using System.Collections.Generic;
  using System.IO;
  using System.IO.Compression;
  using System.Security.Cryptography;
  using dnlib.DotNet;
  using dnlib.DotNet.Emit;
  using ICSharpCode.SharpZipLib.Zip.Compression;
  using de4dot.blocks;
  
  namespace de4dot.code.deobfuscators {
  	public static class DeobUtils {
  		public static void DecryptAndAddResources(ModuleDef module, string encryptedName, Func<byte[]> decryptResource) {
  			Logger.v("Decrypting resources, name: {0}", Utils.ToCsharpString(encryptedName));
  			var decryptedResourceData = decryptResource();
  			if (decryptedResourceData == null)
  				throw new ApplicationException("decryptedResourceData is null");
  			var resourceModule = ModuleDefMD.Load(decryptedResourceData);
  
  			Logger.Instance.Indent();
  			foreach (var rsrc in resourceModule.Resources) {
  				Logger.v("Adding decrypted resource {0}", Utils.ToCsharpString(rsrc.Name));
  				module.Resources.Add(rsrc);
  			}
  			Logger.Instance.DeIndent();
  		}
  
  		public static T Lookup<T>(ModuleDefMD module, T def, string errorMessage) where T : class, ICodedToken {
  			if (def == null)
  				return null;
  			var newDef = module.ResolveToken(def.MDToken.Raw) as T;
  			if (newDef == null)
  				throw new ApplicationException(errorMessage);
  			return newDef;
  		}
  
  		public static byte[] ReadModule(ModuleDef module) => Utils.ReadFile(module.Location);
  
  		public static bool IsCode(short[] nativeCode, byte[] code) {
  			if (nativeCode.Length != code.Length)
  				return false;
  			for (int i = 0; i < nativeCode.Length; i++) {
  				if (nativeCode[i] == -1)
  					continue;
  				if ((byte)nativeCode[i] != code[i])
  					return false;
  			}
  			return true;
  		}
  
  		public static byte[] Md5Sum(byte[] data) => MD5.Create().ComputeHash(data);
  		public static byte[] Sha1Sum(byte[] data) => SHA1.Create().ComputeHash(data);
  		public static byte[] Sha256Sum(byte[] data) => SHA256.Create().ComputeHash(data);
  
  		public static byte[] AesDecrypt(byte[] data, byte[] key, byte[] iv) {
  			using (var aes = new RijndaelManaged { Mode = CipherMode.CBC }) {
  				using (var transform = aes.CreateDecryptor(key, iv)) {
  					return transform.TransformFinalBlock(data, 0, data.Length);
  				}
  			}
  		}
  
  		public static byte[] Des3Decrypt(byte[] data, byte[] key, byte[] iv) {
  			using (var des3 = TripleDES.Create()) {
  				using (var transform = des3.CreateDecryptor(key, iv)) {
  					return transform.TransformFinalBlock(data, 0, data.Length);
  				}
  			}
  		}
  
  		public static byte[] DesDecrypt(byte[] data, int start, int len, byte[] key, byte[] iv) {
  			using (var des = new DESCryptoServiceProvider()) {
  				using (var transform = des.CreateDecryptor(key, iv)) {
  					return transform.TransformFinalBlock(data, start, len);
  				}
  			}
  		}
  
  		// Code converted from C implementation @ http://en.wikipedia.org/wiki/XXTEA (btea() func)
  		public static void XxteaDecrypt(uint[] v, uint[] key) {
  			const uint DELTA = 0x9E3779B9;
  			int n = v.Length;
  			uint rounds = (uint)(6 + 52 / n);
  			uint sum = rounds * DELTA;
  			uint y = v[0];
  			uint z;
  			//#define MX (((z >> 5 ^ y << 2) + (y >> 3 ^ z << 4)) ^ ((sum ^ y) + (key[(p & 3) ^ e] ^ z)))
  			do {
  				int e = (int)((sum >> 2) & 3);
  				int p;
  				for (p = n - 1; p > 0; p--) {
  					z = v[p - 1];
  					y = v[p] -= (((z >> 5 ^ y << 2) + (y >> 3 ^ z << 4)) ^ ((sum ^ y) + (key[(p & 3) ^ e] ^ z)));
  				}
  				z = v[n - 1];
  				y = v[0] -= (((z >> 5 ^ y << 2) + (y >> 3 ^ z << 4)) ^ ((sum ^ y) + (key[(p & 3) ^ e] ^ z)));
  			} while ((sum -= DELTA) != 0);
  		}
  
  		// Code converted from C implementation @ http://en.wikipedia.org/wiki/XTEA (decipher() func)
  		public static void XteaDecrypt(ref uint v0, ref uint v1, uint[] key, int rounds) {
  			const uint delta = 0x9E3779B9;
  			uint sum = (uint)(delta * rounds);
  			for (int i = 0; i < rounds; i++) {
  				v1 -= (((v0 << 4) ^ (v0 >> 5)) + v0) ^ (sum + key[(sum >> 11) & 3]);
  				sum -= delta;
  				v0 -= (((v1 << 4) ^ (v1 >> 5)) + v1) ^ (sum + key[sum & 3]);
  			}
  		}
  
  		public static string GetExtension(ModuleKind kind) {
  			switch (kind) {
  			case ModuleKind.Dll:
  				return ".dll";
  			case ModuleKind.NetModule:
  				return ".netmodule";
  			case ModuleKind.Console:
  			case ModuleKind.Windows:
  			default:
  				return ".exe";
  			}
  		}
  
  		public static byte[] Inflate(byte[] data, bool noHeader) =>
  			Inflate(data, 0, data.Length, noHeader);
  
  		public static byte[] Inflate(byte[] data, int start, int len, bool noHeader) =>
  			Inflate(data, start, len, new Inflater(noHeader));
  
  		public static byte[] Inflate(byte[] data, Inflater inflater) =>
  			Inflate(data, 0, data.Length, inflater);
  
  		public static byte[] Inflate(byte[] data, int start, int len, Inflater inflater) {
  			var buffer = new byte[0x1000];
  			var memStream = new MemoryStream();
  			inflater.SetInput(data, start, len);
  			while (true) {
  				int count = inflater.Inflate(buffer, 0, buffer.Length);
  				if (count == 0)
  					break;
  				memStream.Write(buffer, 0, count);
  			}
  			return memStream.ToArray();
  		}
  
  		public static byte[] Gunzip(Stream input, int decompressedSize) {
  			using (var gzip = new GZipStream(input, CompressionMode.Decompress)) {
  				var decompressed = new byte[decompressedSize];
  				if (gzip.Read(decompressed, 0, decompressedSize) != decompressedSize)
  					throw new ApplicationException("Could not gzip decompress");
  				return decompressed;
  			}
  		}
  
  		public static EmbeddedResource GetEmbeddedResourceFromCodeStrings(ModuleDef module, MethodDef method) {
  			foreach (var s in DotNetUtils.GetCodeStrings(method)) {
  				if (DotNetUtils.GetResource(module, s) is EmbeddedResource resource)
  					return resource;
  			}
  			return null;
  		}
  
  		public static int ReadVariableLengthInt32(byte[] data, ref int index) {
  			byte b = data[index++];
  			if ((b & 0x80) == 0)
  				return b;
  			if ((b & 0x40) == 0)
  				return (((int)b & 0x3F) << 8) + data[index++];
  			return (((int)b & 0x1F) << 24) +
  					((int)data[index++] << 16) +
  					((int)data[index++] << 8) +
  					data[index++];
  		}
  
  		public static bool HasInteger(MethodDef method, uint value) => HasInteger(method, (int)value);
  		public static bool HasInteger(MethodDef method, int value) => IndexOfLdci4Instruction(method, value) >= 0;
  
  		public static int IndexOfLdci4Instruction(MethodDef method, int value) {
  			if (method == null || method.Body == null)
  				return -1;
  			var instrs = method.Body.Instructions;
  			for (int i = 0; i < instrs.Count; i++) {
  				var instr = instrs[i];
  				if (!instr.IsLdcI4())
  					continue;
  				if (instr.GetLdcI4Value() == value)
  					return i;
  			}
  			return -1;
  		}
  
  		public static IEnumerable<MethodDef> GetInitCctors(ModuleDef module, int maxCctors) {
  			var cctor = DotNetUtils.GetModuleTypeCctor(module);
  			if (cctor != null)
  				yield return cctor;
  
  			var entryPoint = module.EntryPoint;
  			if (entryPoint != null) {
  				cctor = entryPoint.DeclaringType.FindStaticConstructor();
  				if (cctor != null)
  					yield return cctor;
  			}
  
  			foreach (var type in module.GetTypes()) {
  				if (type == module.GlobalType)
  					continue;
  				cctor = type.FindStaticConstructor();
  				if (cctor == null)
  					continue;
  				yield return cctor;
  				if (!type.IsEnum && --maxCctors <= 0)
  					break;
  			}
  		}
  
  		public static List<MethodDef> GetAllResolveHandlers(MethodDef method) {
  			var list = new List<MethodDef>();
  			if (method == null || method.Body == null)
  				return list;
  
gt: 			foreach (var instr in method.Body.Instructions) {