/*
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 Mono.Cecil.Cil;
using de4dot.blocks;
using de4dot.blocks.cflow;
namespace de4dot.code.deobfuscators.Confuser {
class ConstantsFolder : BlockDeobfuscator {
protected override bool deobfuscate(Block block) {
bool modified = false;
var instrs = block.Instructions;
var constantsReader = createConstantsReader(instrs);
for (int i = 0; i < instrs.Count; i++) {
int index = 0;
Instruction newInstr = null;
var instr = instrs[i];
if (constantsReader.isLoadConstant32(instr.Instruction)) {
index = i;
int val;
if (!constantsReader.getInt32(ref index, out val))
continue;
newInstr = DotNetUtils.createLdci4(val);
}
else if (constantsReader.isLoadConstant64(instr.Instruction)) {
index = i;
long val;
if (!constantsReader.getInt64(ref index, out val))
continue;
newInstr = Instruction.Create(OpCodes.Ldc_I8, val);
}
if (newInstr == null || index - i <= 1)
continue;
block.insert(index++, Instruction.Create(OpCodes.Pop));
block.insert(index++, newInstr);
i = index - 1;
constantsReader = createConstantsReader(instrs);
modified = true;
}
return modified;
}
static ConstantsReader createConstantsReader(IList instrs) {
return new ConstantsReader(instrs, false);
}
}
}