C# Discussion Boards - CodeProject

13-Dec-08 1:26

Hey

I want to inject DLL made in C# into an Application.
Ive been looking for this for a long time, but still cant find the answer.
In C you would use it like this

BOOL WINAPI DllMain(HINSTANCE hinstDLL, DWORD fdwReason, LPVOID lpvReserved)
{
    switch (fdwReason)
    {
        case DLL_PROCESS_ATTACH:
            // attach to process
            MessageBox(0, "Test", "Test", MB_OK);
            break;

        case DLL_PROCESS_DETACH:
            // detach from process
            break;

        case DLL_THREAD_ATTACH:
            // attach to thread
            break;

        case DLL_THREAD_DETACH:
            // detach from thread
            break;
    }
    return TRUE; // succesful
}

Is there a way to do this in C#? Like when I inject it, that it also shows the MessageBox at successfull injection?
Thanks in Advance
- opx

User 665813-Dec-08 2:19

13-Dec-08 2:19

LoadLibrary[^] will call DllMain for you, so you can use P/Invoke for that task.

regards

modified 12-Sep-18 21:01pm.

OptiPlex13-Dec-08 2:56

13-Dec-08 2:56

Thank you for your kind reply, but I still dont get it.
Im not really familiar with LoadLibrary...
This is what I got so far

using System;
using System.Collections.Generic;
using System.Text;
using System.Runtime.InteropServices;

namespace MyDll
{
    public class clsMain
    {
        [DllImport("kernel32.dll")]
        public static extern IntPtr LoadLibrary(string lpFileName);

        // LibMain here...
    }
}

User 665813-Dec-08 3:11

13-Dec-08 3:11

So did you actually call the method?

LoadLibrary("YourDll.dll");

if this returns some value != IntPtr.Zero then the call was successful.

regards

modified 12-Sep-18 21:01pm.

OptiPlex13-Dec-08 3:37

13-Dec-08 3:37

Thank you

You see, im using a program called Winject to inject the dll. I guess that really does it all.
When it gets injected, it automatically calls the LibMain function and executes the code in my Dll.

But when I try to inject the dll I made in c#, it doesnt get executed, this is the code im using:

using System;
using System.Collections.Generic;
using System.Text;
using System.Runtime.InteropServices;

namespace MyDll
{
    public class clsMain
    {
        [DllImport("kernel32.dll")]
        public static extern IntPtr LoadLibrary(string lpFileName);

        [DllImport("user32.dll")]
        public static extern int MessageBox(int hwnd, string lpText, string lpTitle, int style);

        // LibMain here...
        public void LibMain(IntPtr hInstance, int fdwReason, int reserved)
        {
            MessageBox(0, "Injected from C#", "C# hello world", 0);
        }
    }
}

Thank you very much again!
- opx

User 665813-Dec-08 4:24

13-Dec-08 4:24

I'm confused, do you have a native DLL or a .NET DLL? First, you presented a native DLL, now you're showing me the code of a .NET DLL, which works totally different and where LoadLibrary has no effect on.

modified 12-Sep-18 21:01pm.

OptiPlex13-Dec-08 4:27

13-Dec-08 4:27

I wanted to make a Dll like c but in c#, so yes a native Dll.
I want it to be injected into a process, and not called.

But I guess C# is not really a good language for this, right?

Thanks for your replies
- opx

User 665813-Dec-08 5:11

13-Dec-08 5:11

OptiPlex wrote:
I want it to be injected into a process, and not called.

I'd rather use a native DLL, then.

regards

modified 12-Sep-18 21:01pm.