I am trying to calling a game functions with code injection. after some try I find a dll that did what I want.
so i saw the dll with ILSpy but cannot understand the code.
class <Module>
{
[SecurityCritical, SuppressUnmanagedCodeSecurity]
[DllImport("", CallingConvention = CallingConvention.ThisCall, SetLastError = true)]
[MethodImpl(MethodImplOptions.Unmanaged)]
internal unsafe static extern float* GetHealth(AttackableUnit*);
}
--------------------------
namespace Native
{
[NativeCppClass]
[StructLayout(LayoutKind.Sequential, Size = 1)]
internal struct AttackableUnit
{
}
}
---------------------
public unsafe float MaxHealth
{
get
{
Native.AttackableUnit* ptr = (Native.AttackableUnit*)base.GetPtr();
if (ptr != null)
{
return *<Module>.Native.AttackableUnit.GetMaxHealth(ptr);
}
return 0f;
}
}
Seems the dll inject c# code to the target app with a c++ dll and bootstrap .net in target.
And now I cannot understand what is the meaning of
[DllImport("", CallingConvention = CallingConvention.ThisCall,
SetLastError = true)]
Why is the file path empty?
How does the dll manage class and function call? I mean what technique the programmer use?
EDIT :
The name of library that I am trying to understand is Elobuddy perhaps helps.
Trying not to kick in a wide-open door, the C# language was not involved in generating this assembly. You are seeing the output of a C++/CLI project. A mixed-mode assembly, it contains both MSIL and native code. You'd generate a similar assembly with File > New > Project > Visual C++ > CLR > Class Library.
The author probably favored it to solve the CLR injection problem. It is not possible to inject a pure managed DLL into another process, the CLR has to first be loaded and initialized before it can execute any managed code. A chicken-and-egg problem that requires reverse-pinvoke (native code calling managed code) the opposite of what [DllImport] does. C++/CLI makes that very easy, I describe the technique in this answer. The Unmanaged Exports utility is popular (google DllExport), an assembly rewriter that uses the same technique that C++/CLI uses.
But the author also wanted to use native C++ code to implement the game hack. He is using a pure native DLL, it contains the GetHealth() function and AttackableUnit class definition. This DLL is implicitly loaded by the OS loader, like DLLs usually are, the reason why an empty string for the [DllImport] attribute is good enough. Otherwise necessary, the compiler cannot know which DLL has this native code, that doesn't get sorted out until the linker runs and uses the import library of the native DLL.
The C++/CLI compiler goes a bit overboard emitting metadata for the pure native constructs in the code. But does its best to make them look as much as possible like their managed equivalents. Do note it is very incomplete, you can't for example see the names of the members of the AttackableUnit C++ class. You will find a lot of other spew in the assembly, a lot of CRT declarations make it into the metadata as well. The native linker does not do a terrific job of hiding it. Mostly because it doesn't have to, this code is pretty well isolated into the internal <Module> class.
Decompiling the machine code for native functions like GetHealth back to the original C++ code is not generally possible. Especially the optimizer built into the back-end of the compiler does a terrific job of making it next to impossible to guess what the original code might have looked like. Hex-Rays is usually mentioned as a machine code decompiler that does a credible job of at least correctly identifying code vs data.
Related
I have a code written in C++ (that I did not write) and want to use it in C#, so I decided to make a dll and use this class from there.
I have very little knowledge of C++ and am having problems referencing the methods of this class in my C# project.
The C++ code is like this:
#ifndef BeamAn_class
#define BeamAn_class
#define DllExport __declspec( dllexport )
#include <vector>
#include <cmath>
using namespace std;
public class DllExport BeamAn
{
public:
BeamAn();
~BeamAn();
bool SetGeometry(vector<double>); //I didn't put the DllExport here because I already did it for the whole class. It's okay to do this, right?
//other public methods an stuff
private:
//private methods an stuff
}
#endif
In my C# project I added the reference to the C++ dll normally (right click on the project, add reference. The .lib and .h files are in the same folder of the dll).
But looks like Visual Studio can't "see" the methods of my class. I can create a object of the BeamAn type, but can't use any of its methods.
For example, I can do this:
BeamAn contBeam = new BeamAn();
But can't use any of the methods or atributes inside the class, like this: contBeam.SetLoadFactors(1.0,1.2);
Visual Studio says that "BeamAn does not contain a definition for 'SetLoadFactors' and no extension method 'SetLoadFactors' accepting a first argument type 'BeamAn' could be found (are you missing a using directive or an assembly reference?)
Is there more something I should write in the C++ code to make the dll work properly, or am I doing something wrong when referencing it? I know that I'd have to use "DllImport" in my C# code if I was explicit linking, but that's not what I want to do.
Thank you very much!
There are several ways to make C++ library available in C#.
Use PInvoke - directly call your C++ code. See this article for more information. Also see pinvoke.net for general reference.
Use an interop language to create a managed wrapper around your unmanaged code. If you're in the Microsoft world I would recommend C++/CLI to create mixed mode libraries (dlls that contain both managed and unmanaged code). Here is a brief (and old) article introducing C++/CLI.
Make your C++ COM accessible. Since the code isn't yours this one might not be useful to you. See this post for more information about C++ and COM.
For simple scenarios PInvoke is probably the easiest. For more complicated interactions of the managed and unmanaged code I would recommend writing a mixed mode dll with an interop language. And if those don't work for you, use COM.
To address the error you receive: you can't add a reference to a C++ library from a C# project - they are completely different languages with different memory management systems, different type systems, different everything (well, a lot of things). Also, you can't pass data structures (like vectors, maps or sets) from unmanaged code to managed code.
to use c++ code in a c# project, you have 2 options:
wrap your c++ class in a managed c++ class
use a library called swig
a link that might interest you: Wrapping Visual C++ in C#
As the title says i want to call a mixed mode assembly from unmanaged code.
To be more precise, i want to load the mixed mode assembly dynamically and then execute some static unmanaged startup code that registers some Managed C++ Wrappers for C# Code.
Is this possible (or do i need to embed the .Net Runtime or use COM?) ?
Has anybody already done this and can share some experience?
PS: If the mixed mode assembly contains a WPF Window will it be started?
You need to get the CLR loaded and initialized. Yes, making a managed class [ComVisible] or hosting the CLR yourself with CorBindToRuntimeEx() is a way to do this. A very simple way is to export a managed function from your DLL, the C++/CLI compiler embeds a thunk in the code that takes care of initializing the CLR. Very easy to do but it does not scale well when the interface to your managed code is fat.
ref class Bootstrap
{
public:
static void Initialize() {
// etc..
}
};
extern "C" __declspec(dllexport)
void __stdcall LoadAndInitialize()
{
Bootstrap::Initialize();
}
You could embellish by passing a function pointer to your native interface. Convert it to a managed delegate with Marshal::GetDelegateForFunctionPointer(). Don't forget to wrap any native declarations with #pragma managed if you do this.
This question might seem a repeat of previous ones. I have read through a series of posts, but not completely clear for my situation.
I have a c++ library which is created using momentics IDE. I have to be able to use this library into a c# project.
Someone had been working on this project before being handed over to me. Currently, there are 2 layers for making this possible. First, a c++ project includes the complete library with a c++ wrapper. This project creates a dll as the output. This c++ dll is then fed to a c# project, which has dllimport calls to the c++ dll. This c# project again creates a dll. Finally, in order to use the library in c# application, I have to include a reference to both of these dlls.
Is this the correct way to get it working? I was thinking probably there should be a way to simplify the process.
Can someone please help me with this question?
Given that you're using a C++ library, I'm assuming it takes advantage of C++ semantics like classes, rather than just exposing procedures. If this is the case, then the way this is typically done is via a manually-created managed C++ interop library.
Basically, you create a managed C++ library in Visual Studio, reference your existing C++ library, and create a managed wrapper around your existing C++ classes. You then reference this (managed) C++ assembly in your C# project and include the original (unmanaged) C++ library in your C# assembly just as a file that gets placed in the build directory.
This is required because there is no way to reference things like C++ classes via P/Invoke (DllImport) calls.
If your base library is just a series of functions, then you can reference that directly in the C# project via P/Invoke functions.
Either way, all of the libraries mentioned above (for the first, the unmanaged C++ library, the managed C++ assembly, and the C# project, or, for the second, the unmanaced C++ library and the C# project) must be included in any project that references them. You cannot statically link the unmanaged library into the managed assembly.
Seems like you have one wrapper too many but perhaps someone is implementing some sort of facade or adding properties or something. The basic connection between managed and unmanaged will be either DllImport of "flat" function calls - not member functions - or C++/CLI code calling member functions. If the wrapper is C++/CLI it's easiest to write (just include the header for the C++ library) and easiest to call (C# code just adds a .NET reference to it and carries on as normal) so it would be my first choice if there's C++ expertise on the project.
It sounds like whoever you were taking over from is doing it the hard way. If there are less than 20 methods, I would suggest starting over.
You can use:
DllImport
class Example
{
// Use DllImport to import the Win32 MessageBox function.
[DllImport("user32.dll", CharSet = CharSet.Unicode)]
public static extern int MessageBox(IntPtr hWnd, String text, String caption, uint type);
static void Main()
{
// Call the MessageBox function using platform invoke.
MessageBox(new IntPtr(0), "Hello World!", "Hello Dialog", 0);
}
}
I'm attempting to consume a dll written in C++ from a C# application. I have 3rd party source code for the C++ dll (the Cyclone physics engine) and do not want to manually port it over to C#.
In the C++ project
I changed it to output a dll. I changed it to use the /clr flag. I changed it to use Multi-threaded Debug DLL (/MDd) because that was the only one compatible with /clr and also compiled.
In the C# project
I added a reference to the dll. I'm using the cyclone namespace.
At first there was absolutely nothing under the namespace. I think this is because in the C++ code, all classes were declared with no access modifiers and the default is private. So for the class "Particle" I changed the definition to:
public class Particle
{
//...
}
Now I can successfully declare a variable of type Particle from the C# code. However, intellesense and the object browser report Particle to be a struct (?) and it doesn't contain any methods at all. The c++ code declares a bunch of methods after "public:" access modifiers so I don't know what the problem is.
For example,
public:
void integrate(real duration);
What am I doing wrong?
The Particle class is not a managed class, hence it is treated as a struct. You need to use the ref keyword to make it managed and garbage collected. You also need to do the same to every other class that references it which might be a problem. The best solution I think, is to create a managed wrapper class that uses the Particle class internally. This wrapper class can then be referenced by .net.
See here:
I have not actually run into your exact problem before, but I have used C++ dlls in c# before. Typically when calling a dll like that you would use the dllImport keyword. Basically you can define a class that imports all the types and methods from the c++ dll. You can then call those wrapper classes.
I am far from an expert on it, but I have used it to get access to win32 methods and some other libraries that I needed to use.
This link on codeplex has a few links tools that might help. But the most important is probably the Interop Assistant. It can generate the C# wrappers for your c++ dll.
This isn't exactly what you are asking, but I thought it might help to look at a different direction.
Try declaring the c++ class with the ref keyword:
public ref class Particle
Do you have a reference to COM Interop?
I have a C++ class I'd like to access from a C# application. I'll need to access the constructor and a single member function. Currently the app accepts data in the form of stl::vectors but I can do some conversion if that's not likely to work?
I've found a few articles online which describe how to call C++ DLLs and some others which describe how to make .dll projects for other purposes. I'm struggling to find a guide to creating them in Visual Studio 2008 for use in a C# app though (there seem to be a few for VS 6.0 but the majority of the options they specify don't seem to appear in the 2008 version).
If anyone has a step-by-step guide or a fairly basic example to get going from, I'd be very grateful.
The easiest way to interoperate between C++ and C# is by using managed C++, or C++/CLI as it is called. In VisualStudio, create a new C++ project of type "CLR Class Library". There is some new syntax for the parts that you want to make available to C#, but you can use regular C++ as usual.
In this example, I'm using std::vector<int> just to show that you can use standard types - however, in an actual application, I'd prefer to use the .NET types where possible (in this case a System::Collections::Generic::List<int>).
#pragma unmanaged
#include <vector>
#pragma managed
public ref class CppClass
{
public:
CppClass() : vectorOfInts_(new std::vector<int>)
{}
// This is a finalizer, run when GC collects the managed object
!CppClass()
{ delete vectorOfInts_; }
void Add(int n)
{ vectorOfInts_->push_back(n); }
private:
std::vector<int>* vectorOfInts_;
};
EDIT: Changed the class to hold the vector by pointer instead of by value.
If such DLL is unmanaged. You will have to use P/invoke. A p/invoke function definition looks like this:
[DllImport("Library_Name.dll", EntryPoint = "function")]
public static extern void function();
If, on the other hand, is a managed (C++/CLI) DLL (or assembly). You can access it by adding a reference to it on your .NET project.
EDIT:
I think I didn't answer your question at all. But to create a managed C++ DLL to be accessed from .NET, create a new project an choose:
Visual C++/CLR/Class Library. And then, just add its output DLL to your C# project.
That'd do it. :)
Do you have an existing C++ exe that you want to re-build as a dll? Or is all you have the C++ class?
If all you have is the C++ class, you might think about building a .Net dll. While you couldn't pass stl types from C# to C++, I am pretty sure you can pass managed .Net types.
If you must use the stl types in the class, you could convert the data in the C++ class, or the calling app.
I've found a tutorial which works. A quick note though, you have to be careful to copy the .dll into the same directory as the executable. I messed around with trying to tell the executable where the DLL was but gave up in the end.
Use of unmanaged C++ Dlls can be very tedious in C#.
An "easier" route is to place it in a COM wrapper.