How to call a C++ exported function from C#, in another process?

Question

I haven't found anything useful related to this problem after some serious google lurking, so I'll ask it here.

I have a program that's made in C# that injects a DLL into another process, fairly trivial. It Calls CreateRemoteThread and LoadLibrary from kernel32.dll with [DllImport].

My DLL once loaded then waits for authentication from the C# program, due to security reasons, I can't have this data transferred using sockets. So I have my DLL export a function that's planned to be called from the C# program with authentication data.

The exported function takes two arguments, it is as follows :

extern "C" __declspec(dllexport) void DoStuff( const char* ccString1, const char* ccString2 ){

    // Do stuff

}

Since as the DLL isn't in the same address space as the C# program, I can't use [DllImport] to get and the call the exported function.

My second idea was to use CreateRemoteThread to call the function, though that can only be passed 1 argument whereas I need two, it'd also be difficult because I'd need to call the return of GetProcAddress, I can't simply call by exported function directly.

So, how would I go about achieving this?

Thanks

Answer 1

[DllImport] is the same as GetProcAddress. C# does not load the DLL until the first call, so the .NET can do the security checks before calling the DLL.

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If you don't trust the DLL at all, then it's better to split de C# program in two. One program connected via Remoting/WCF/IPC to the second one, and the second one connects to the C DLL via DllImport. This solution is typically used when you don't trust C DLL stability or memory allocation because the second program (the one that call de C DLL) can be restarted without restarting the main program. Example of this pattern: some windows drivers (with the exception that they don't use C# at this time).

Answer 2

您可以使用非持久内存映射文件在应用程序和DLL之间交换数据。