/*
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;
using Mono.Cecil.Cil;
using de4dot.blocks;
namespace de4dot.code.deobfuscators {
class ExceptionLoggerRemover {
Dictionary exceptionLoggerMethods = new Dictionary();
public int NumRemovedExceptionLoggers { get; set; }
public void add(MethodDefinition exceptionLogger) {
exceptionLoggerMethods[exceptionLogger] = true;
}
bool find(Blocks blocks, out TryBlock tryBlock) {
tryBlock = null;
foreach (var bb in blocks.MethodBlocks.BaseBlocks) {
tryBlock = bb as TryBlock;
if (tryBlock == null)
continue;
if (tryBlock.TryHandlerBlocks.Count != 1)
continue;
var catchBlock = tryBlock.TryHandlerBlocks[0];
if (catchBlock.HandlerType != ExceptionHandlerType.Catch ||
catchBlock.CatchType.FullName != "System.Exception") {
continue;
}
if (catchBlock.BaseBlocks.Count != 1)
continue;
var handlerBlock = catchBlock.BaseBlocks[0] as HandlerBlock;
if (handlerBlock == null)
continue;
int calls = 0;
Instr callInstr = null;
bool failed = false;
foreach (var bb2 in handlerBlock.BaseBlocks) {
var block = bb2 as Block;
if (block == null) {
failed = true;
break;
}
foreach (var instr in block.Instructions) {
switch (instr.OpCode.Code) {
case Code.Call:
case Code.Calli:
case Code.Callvirt:
calls++;
callInstr = instr;
break;
}
}
}
if (failed || calls != 1 || callInstr.OpCode.Code != Code.Call)
continue;
var calledMethod = callInstr.Operand as MethodReference;
if (calledMethod == null)
continue;
if (!isExceptionLogger(calledMethod))
continue;
return true;
}
return false;
}
protected virtual bool isExceptionLogger(MethodReference method) {
return exceptionLoggerMethods.ContainsKey(method);
}
protected virtual bool HasExceptionLoggers {
get { return exceptionLoggerMethods.Count != 0; }
}
public bool remove(Blocks blocks) {
if (!HasExceptionLoggers)
return false;
TryBlock tryBlock;
if (!find(blocks, out tryBlock))
return false;
blocks.MethodBlocks.removeTryBlock(tryBlock);
NumRemovedExceptionLoggers++;
return true;
}
}
}