Can't "return" from function - HELP!

[Marton]

Hi all, I'm dealing with this function:

http://cablemodem.fibertel.com.ar/marton79/func.txt

It is called like this:

private void btnOK_Click(object sender, EventArgs e)
{
    ClientSessionManager.Instance.SaveAndSetServerInfos(this.serverInfos);
    if (ActivationHandler.Activator.GetStrongestEdition(new Product(Product.ProductTypes.prApplication)) == null)
    {
        MessageBox.Show(this, ApplicationResourceManager.Instance.GetString("Project.ActivationForm.NeedActivtion.Text"), ApplicationResourceManager.Instance.GetString("Project.ActivationForm.NeedActivtion.Caption"), MessageBoxButtons.OK, MessageBoxIcon.Asterisk);
    }
    base.Close();
}

Why, WHY I can't just return 1 or any needed result from the GetStrongestEdition funcion? If I do that, I get a General Error on program launch and it closes. If I patch the last return, the message box still shows up, but the return is executing because if I nop it out, the program crashes.
I spent many hours trying to figure this out but it is beyond my knowledge. I could make a donation to anyone who could help me achieve the goal

TIA

[Git]

Donations not allowed here, unless to charity.

It sounds like the program has verification in the form of CRC or hashing of some kind. Disassemble near the start of the program and you should find it. It may help to run a crypto/hash detector on the exe.

Git

[kao]

Sure you can do it, you just need to be extremely careful when patching your program. The crashes you see most likely come from .NET framework detecting invalid IL code or type.

The proper code should look like this:

edition = new Edition(Edition.EditionTypes.edApplicationServerStandard);  // or whatever edition you like
return edition;

The hard part is to nop out all the useless code and fix all the try/catch/fault blocks. Since your program seems to be mixed-mode assembly, almost none of the usual tools will work properly.

I'd use hex editor/CFF for patching and ILDASM/PEVERIFY to verify that I didn't mess up.

[Marton]

Thanks for the tips!
I'll try manually coding it with the hex editor and try to get it as kao suggests. Is it OK to fill the rest of the function with nops till the end, or something else is required?
Will post the results
Thanks again!

[DotNetResearcher2]

Originally Posted by kao

I'd use hex editor/CFF for patching and ILDASM/PEVERIFY to verify that I didn't mess up.

On a related but tangential note, I've been enjoying using UltraEdit as a hex editor - for anything other than a single edit, it's better than CFF.

DNR

[bball0002]

I think it's very easy to edit methods with CFF explorer. You can go to the methods table and highlight instructions, right click -> nop. You can also edit branches this way.