/*
Copyright (C) 2011-2014 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 .
*/
using System;
using System.Collections.Generic;
using dnlib.DotNet;
using dnlib.DotNet.Emit;
using de4dot.blocks;
namespace de4dot.code.deobfuscators.DeepSea {
class ArrayBlockState {
ModuleDefMD module;
FieldDefAndDeclaringTypeDict fieldToInfo = new FieldDefAndDeclaringTypeDict();
public class FieldInfo {
public readonly ElementType elementType;
public readonly FieldDef field;
public readonly FieldDef arrayInitField;
public readonly Array array;
public FieldInfo(FieldDef field, FieldDef arrayInitField) {
this.field = field;
this.elementType = ((SZArraySig)field.FieldType).Next.GetElementType();
this.arrayInitField = arrayInitField;
this.array = CreateArray(elementType, arrayInitField.InitialValue);
}
static Array CreateArray(ElementType etype, byte[] data) {
switch (etype) {
case ElementType.Boolean:
case ElementType.I1:
case ElementType.U1:
return (byte[])data.Clone();
case ElementType.Char:
case ElementType.I2:
case ElementType.U2:
var ary2 = new ushort[data.Length / 2];
Buffer.BlockCopy(data, 0, ary2, 0, ary2.Length * 2);
return ary2;
case ElementType.I4:
case ElementType.U4:
var ary4 = new uint[data.Length / 4];
Buffer.BlockCopy(data, 0, ary4, 0, ary4.Length * 4);
return ary4;
default:
throw new ApplicationException("Invalid etype");
}
}
public uint ReadArrayElement(int index) {
switch (elementType) {
case ElementType.Boolean:
case ElementType.I1:
case ElementType.U1:
return ((byte[])array)[index];
case ElementType.Char:
case ElementType.I2:
case ElementType.U2:
return ((ushort[])array)[index];
case ElementType.I4:
case ElementType.U4:
return ((uint[])array)[index];
default:
throw new ApplicationException("Invalid etype");
}
}
}
public bool Detected {
get { return fieldToInfo.Count != 0; }
}
public ArrayBlockState(ModuleDefMD module) {
this.module = module;
}
public void Initialize(ISimpleDeobfuscator simpleDeobfuscator) {
InitializeArrays(simpleDeobfuscator, DotNetUtils.GetModuleTypeCctor(module));
}
void InitializeArrays(ISimpleDeobfuscator simpleDeobfuscator, MethodDef method) {
if (method == null || method.Body == null)
return;
while (InitializeArrays2(simpleDeobfuscator, method)) {
}
}
bool InitializeArrays2(ISimpleDeobfuscator simpleDeobfuscator, MethodDef method) {
bool foundField = false;
simpleDeobfuscator.Deobfuscate(method, SimpleDeobfuscatorFlags.Force);
var instructions = method.Body.Instructions;
for (int i = 0; i < instructions.Count; i++) {
var ldci4 = instructions[i];
if (!ldci4.IsLdcI4())
continue;
i++;
var instrs = DotNetUtils.GetInstructions(instructions, i, OpCodes.Newarr, OpCodes.Dup, OpCodes.Ldtoken, OpCodes.Call, OpCodes.Stsfld);
if (instrs == null)
continue;
var arrayInitField = instrs[2].Operand as FieldDef;
if (arrayInitField == null || arrayInitField.InitialValue == null || arrayInitField.InitialValue.Length == 0)
continue;
var calledMethod = instrs[3].Operand as IMethod;
if (calledMethod == null || calledMethod.FullName != "System.Void System.Runtime.CompilerServices.RuntimeHelpers::InitializeArray(System.Array,System.RuntimeFieldHandle)")
continue;
var targetField = instrs[4].Operand as FieldDef;
if (targetField == null || targetField.FieldType.GetElementType() != ElementType.SZArray)
continue;
var etype = ((SZArraySig)targetField.FieldType).Next.GetElementType();
if (etype < ElementType.Boolean || etype > ElementType.U4)
continue;
if (fieldToInfo.Find(targetField) == null) {
fieldToInfo.Add(targetField, new FieldInfo(targetField, arrayInitField));
foundField = true;
}
}
return foundField;
}
public FieldInfo GetFieldInfo(IField fieldRef) {
if (fieldRef == null)
return null;
return fieldToInfo.Find(fieldRef);
}
public IEnumerable CleanUp() {
var removedFields = new List();
var moduleCctor = DotNetUtils.GetModuleTypeCctor(module);
if (moduleCctor == null)
return removedFields;
var moduleCctorBlocks = new Blocks(moduleCctor);
var keep = FindFieldsToKeep();
foreach (var fieldInfo in fieldToInfo.GetValues()) {
if (keep.ContainsKey(fieldInfo))
continue;
if (RemoveInitCode(moduleCctorBlocks, fieldInfo)) {
removedFields.Add(fieldInfo.field);
removedFields.Add(fieldInfo.arrayInitField);
}
fieldInfo.arrayInitField.InitialValue = new byte[1];
fieldInfo.arrayInitField.FieldSig.Type = module.CorLibTypes.Byte;
fieldInfo.arrayInitField.RVA = 0;
}
IList allInstructions;
IList allExceptionHandlers;
moduleCctorBlocks.GetCode(out allInstructions, out allExceptionHandlers);
DotNetUtils.RestoreBody(moduleCctorBlocks.Method, allInstructions, allExceptionHandlers);
return removedFields;
}
bool RemoveInitCode(Blocks blocks, FieldInfo info) {
bool removedSomething = false;
foreach (var block in blocks.MethodBlocks.GetAllBlocks()) {
var instrs = block.Instructions;
for (int i = 0; i < instrs.Count - 5; i++) {
var ldci4 = instrs[i];
if (!ldci4.IsLdcI4())
continue;
if (instrs[i + 1].OpCode.Code != Code.Newarr)
continue;
if (instrs[i + 2].OpCode.Code != Code.Dup)
continue;
var ldtoken = instrs[i + 3];
if (ldtoken.OpCode.Code != Code.Ldtoken)
continue;
if (ldtoken.Operand != info.arrayInitField)
continue;
var call = instrs[i + 4];
if (call.OpCode.Code != Code.Call)
continue;
var calledMethod = call.Operand as IMethod;
if (calledMethod == null || calledMethod.FullName != "System.Void System.Runtime.CompilerServices.RuntimeHelpers::InitializeArray(System.Array,System.RuntimeFieldHandle)")
continue;
var stsfld = instrs[i + 5];
if (stsfld.OpCode.Code != Code.Stsfld)
continue;
if (stsfld.Operand != info.field)
continue;
block.Remove(i, 6);
i--;
removedSomething = true;
}
}
return removedSomething;
}
Dictionary FindFieldsToKeep() {
var keep = new Dictionary();
foreach (var type in module.GetTypes()) {
foreach (var method in type.Methods) {
if (type == DotNetUtils.GetModuleType(module) && method.Name == ".cctor")
continue;
if (method.Body == null)
continue;
foreach (var instr in method.Body.Instructions) {
var field = instr.Operand as IField;
if (field == null)
continue;
var fieldInfo = fieldToInfo.Find(field);
if (fieldInfo == null)
continue;
keep[fieldInfo] = true;
}
}
}
return keep;
}
}
}