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Leafy

[DNLib] Method is not defined in this Module

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Leafy

If i try to insert a call after a Instruction im getting a Method is not defined in this Module Exception

using dnlib.DotNet;
using dnlib.DotNet.Emit;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;

namespace LeafObfuscator.Protection
{
    //TODO: Fix
    class Int32
    {
        public static void encode(ModuleDefMD md)
        {
            Inject.injectmethods(md,Int(md));

            foreach (TypeDef type in md.Types)
            {
                foreach (MethodDef method in type.Methods)
                {
                    CilBody body = method.Body;
                    if (!method.HasBody) { continue; }
                    for (int i = 0; i < body.Instructions.Count; i++)
                    {
                        if (method.Name != "dec")
                        {
                            if (body.Instructions[i].OpCode == OpCodes.Ldc_I4)
                            {

                                body.Instructions[i].Operand = Convert.ToInt32(body.Instructions[i].Operand) - 10;
                                body.Instructions.Insert(i + 1, Instruction.Create(OpCodes.Call, Int(md)));

                            }
                        }
                    }
                }
            }
        }

        private static MethodDef Int(ModuleDefMD md)
        {
            MethodImplAttributes methImplFlags = MethodImplAttributes.IL | MethodImplAttributes.Managed;
            MethodAttributes methFlags = MethodAttributes.Public | MethodAttributes.Static | MethodAttributes.HideBySig | MethodAttributes.ReuseSlot;

            MethodDef inthider = new MethodDefUser("dec",
                        MethodSig.CreateStatic(md.CorLibTypes.Int32, md.CorLibTypes.Int32),
            methImplFlags, methFlags);
            CilBody body = new CilBody();
            inthider.Body = body;

            body.Instructions.Add(Instruction.Create(OpCodes.Ldc_I4, 10));
            body.Instructions.Add(Instruction.Create(OpCodes.Ldarg_0));
            body.Instructions.Add(Instruction.Create(OpCodes.Add));
            body.Instructions.Add(Instruction.Create(OpCodes.Ret));
            return inthider;
        }

    }
}
 

 

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kao

You did not add your method to the appropriate class (main module in your case). See dnlib\Examples\Example2.cs, line 35.

EDIT: your coding is terrible. You added one method to the module in the very beginning. But then you call "Int(md)" again in the loop - which creates a new method every time. And these new methods are not added to any class.

 

Edited by kao (see edit history)

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Leafy
18 minutes ago, kao said:

You did not add your method to the appropriate class (main module in your case). See dnlib\Examples\Example2.cs, line 35.

EDIT: your coding is terrible. You added one method to the module in the very beginning. But then you call "Int(md)" again in the loop - which creates a new method every time. And these new methods are not added to any class.

 

 My injecter injects the method into <Module>

    class Inject
    {
    
    public static MethodDef injectmethods(ModuleDefMD md, MethodDef method)
    {
        foreach (TypeDef type in md.Types)
        {
            if (type.Name == "<Module>")
            {
                MethodDef decmethod = method;
                type.Methods.Add(decmethod);
                return decmethod;
            }
        }
        throw new Exception("failed");
    }
}
}

 

Edited by Leafy (see edit history)

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Etor Madiv

A little fix would be to not create a new dec every time you encouter an ldc.i4 opcode, you create the dec method just one time and then reuse it across the module

        public static void encode(ModuleDefMD md)
        {
            MethodDef intDecoder = Int(md); //Create just one dec method and reuse it.
            Inject.injectmethods(md, intDecoder);

            foreach (TypeDef type in md.Types)
            {
                foreach (MethodDef method in type.Methods)
                {
                    CilBody body = method.Body;
                    if (!method.HasBody) { continue; }
                    for (int i = 0; i < body.Instructions.Count; i++)
                    {
                        if (method.Name != "dec")
                        {
                            if (body.Instructions[i].OpCode == OpCodes.Ldc_I4)
                            {

                                body.Instructions[i].Operand = Convert.ToInt32(body.Instructions[i].Operand) - 10;
                                body.Instructions.Insert(i + 1, Instruction.Create(OpCodes.Call, intDecoder)); //Do not create a new one every time, they are not the same.

                            }
                        }
                    }
                }
            }
        }

You should also note that not all int values will get affected by your code, you should consider supporting ldc.i4.x opcodes in addition.

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