/*
Copyright (C) 2011-2012 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.Collections.Generic;
using dot10.DotNet;
using dot10.DotNet.Emit;
using de4dot.blocks;
using de4dot.blocks.cflow;
namespace de4dot.code.deobfuscators {
static class ArrayFinder {
public static List getArrays(MethodDef method) {
return getArrays(method, null);
}
public static List getArrays(MethodDef method, IType arrayElementType) {
var arrays = new List();
var instrs = method.Body.Instructions;
for (int i = 0; i < instrs.Count; i++) {
IType type;
var ary = getArray(instrs, ref i, out type);
if (ary == null)
break;
if (arrayElementType != null && !new SigComparer().Equals(type, arrayElementType))
continue;
arrays.Add(ary);
}
return arrays;
}
public static byte[] getArray(IList instrs, ref int index, out IType type) {
for (int i = index; i < instrs.Count - 2; i++) {
var newarr = instrs[i++];
if (newarr.OpCode.Code != Code.Newarr)
continue;
if (instrs[i++].OpCode.Code != Code.Dup)
continue;
var ldtoken = instrs[i++];
if (ldtoken.OpCode.Code != Code.Ldtoken)
continue;
var field = ldtoken.Operand as FieldDef;
if (field == null || field.InitialValue == null)
continue;
index = i - 3;
type = newarr.Operand as IType;
return field.InitialValue;
}
index = instrs.Count;
type = null;
return null;
}
public static byte[] getInitializedByteArray(MethodDef method, int arraySize) {
int newarrIndex = findNewarr(method, arraySize);
if (newarrIndex < 0)
return null;
return getInitializedByteArray(arraySize, method, ref newarrIndex);
}
public static byte[] getInitializedByteArray(int arraySize, MethodDef method, ref int newarrIndex) {
var resultValueArray = getInitializedArray(arraySize, method, ref newarrIndex, Code.Stelem_I1);
var resultArray = new byte[resultValueArray.Length];
for (int i = 0; i < resultArray.Length; i++) {
var intValue = resultValueArray[i] as Int32Value;
if (intValue == null || !intValue.allBitsValid())
return null;
resultArray[i] = (byte)intValue.value;
}
return resultArray;
}
public static short[] getInitializedInt16Array(int arraySize, MethodDef method, ref int newarrIndex) {
var resultValueArray = getInitializedArray(arraySize, method, ref newarrIndex, Code.Stelem_I2);
var resultArray = new short[resultValueArray.Length];
for (int i = 0; i < resultArray.Length; i++) {
var intValue = resultValueArray[i] as Int32Value;
if (intValue == null || !intValue.allBitsValid())
return null;
resultArray[i] = (short)intValue.value;
}
return resultArray;
}
public static int[] getInitializedInt32Array(int arraySize, MethodDef method, ref int newarrIndex) {
var resultValueArray = getInitializedArray(arraySize, method, ref newarrIndex, Code.Stelem_I4);
var resultArray = new int[resultValueArray.Length];
for (int i = 0; i < resultArray.Length; i++) {
var intValue = resultValueArray[i] as Int32Value;
if (intValue == null || !intValue.allBitsValid())
return null;
resultArray[i] = (int)intValue.value;
}
return resultArray;
}
public static uint[] getInitializedUInt32Array(int arraySize, MethodDef method, ref int newarrIndex) {
var resultArray = getInitializedInt32Array(arraySize, method, ref newarrIndex);
if (resultArray == null)
return null;
var ary = new uint[resultArray.Length];
for (int i = 0; i < ary.Length; i++)
ary[i] = (uint)resultArray[i];
return ary;
}
public static Value[] getInitializedArray(int arraySize, MethodDef method, ref int newarrIndex, Code stelemOpCode) {
var resultValueArray = new Value[arraySize];
var emulator = new InstructionEmulator(method);
var theArray = new UnknownValue();
emulator.push(theArray);
var instructions = method.Body.Instructions;
int i;
for (i = newarrIndex + 1; i < instructions.Count; i++) {
var instr = instructions[i];
if (instr.OpCode.FlowControl != FlowControl.Next)
break;
if (instr.OpCode.Code == Code.Newarr)
break;
switch (instr.OpCode.Code) {
case Code.Newarr:
case Code.Newobj:
goto done;
case Code.Stloc:
case Code.Stloc_S:
case Code.Stloc_0:
case Code.Stloc_1:
case Code.Stloc_2:
case Code.Stloc_3:
case Code.Starg:
case Code.Starg_S:
case Code.Stsfld:
case Code.Stfld:
if (emulator.peek() == theArray && i != newarrIndex + 1 && i != newarrIndex + 2)
goto done;
break;
}
if (instr.OpCode.Code == stelemOpCode) {
var value = emulator.pop();
var index = emulator.pop() as Int32Value;
var array = emulator.pop();
if (ReferenceEquals(array, theArray) && index != null && index.allBitsValid()) {
if (0 <= index.value && index.value < resultValueArray.Length)
resultValueArray[index.value] = value;
}
}
else
emulator.emulate(instr);
}
done:
if (i != newarrIndex + 1)
i--;
newarrIndex = i;
return resultValueArray;
}
static int findNewarr(MethodDef method, int arraySize) {
for (int i = 0; ; i++) {
int size;
if (!findNewarr(method, ref i, out size))
return -1;
if (size == arraySize)
return i;
}
}
public static bool findNewarr(MethodDef method, ref int i, out int size) {
var instructions = method.Body.Instructions;
for (; i < instructions.Count; i++) {
var instr = instructions[i];
if (instr.OpCode.Code != Code.Newarr || i < 1)
continue;
var ldci4 = instructions[i - 1];
if (!ldci4.IsLdcI4())
continue;
size = ldci4.GetLdcI4Value();
return true;
}
size = -1;
return false;
}
}
}