C# working with interfaces in unmanaged DLL

[EDN Admin]

I dont know how to work with interfaces, described in header files. Please show me good articles with examples or tell what to do )
I really hope, that i can do it with C# (not C++). <span style="font-family:Courier New; font-size:x-small


I have:
- old DLL (c++/C);
- header files (one with methods and one with GUID);
- lib files (what for?).
!NO SOURCES!

here is some code in .h file:

<pre lang="x-cpp #ifdef __BUILD_DLL
#define BLNETPASS_EXPORT __declspec(dllexport)
#else
#define BLNETPASS_EXPORT
#endif

#include "BlNetpassUid.h"

extern "C"
{
BLNETPASS_EXPORT HRESULT WINAPI BlNetPassCreateA
(LPCSTR pHostName, const GUID *, VOID **);

BLNETPASS_EXPORT HRESULT WINAPI BlNetPassCreateW
(LPCWSTR pHostName, const GUID *, VOID **);

BLNETPASS_EXPORT HRESULT WINAPI CanBeUnload (DWORD dTimeout );

...
...
...

#ifdef UNICODE
#define BlNetPassCreate BlNetPassCreateW
#else
#define BlNetPassCreate BlNetPassCreateA
#endif

#undef INTERFACE
#define INTERFACE INetPass
DECLARE_INTERFACE_ (INetPass, IUnknown)
{
// IUnknown methods

STDMETHOD ( QueryInterface)(REFIID, VOID **) PURE;
STDMETHOD_ (ULONG, AddRef)() PURE;
STDMETHOD_ (ULONG, Release)() PURE;

// INetPass methods

STDMETHOD ( CreateNetPassEnum)(VOID **, REFIID cid,
REFIID iid) PURE;
};[/code]

and maybe another header would be useful

<pre lang="x-cpp DEFINE_GUID (CLSID_MatchBook , 0x40eb613d,0xa77c,0x40db,0xa4,0x8e,0xbc,0xc4,0x9f,0x13,0x15,0x73);

DEFINE_GUID (CLSID_BlackBox , 0xb18e7ff6,0x97db,0x463e,0x9e,0xa8,0x46,0xc8,0x0a,0xc4,0x0c,0x6a);

DEFINE_GUID (IID_INetPassEnum , 0xe74a0be4,0x7dab,0x4c8d,0x82,0xe0,0x77,0x90,0x9f,0x27,0xaa,0xed);

DEFINE_GUID (IID_INetPassDevice , 0xaf0d9f29,0xe4b1,0x415d,0xbb,0x65,0xed,0x64,0x23,0x3e,0xe7,0xe1);

...
...[/code]

what i need:
- call BlNetPassCreateA;
- get pointer to interface INetPass (he has no GUID in .h);
- run interface method CreateNetPassEnum;
- get pointer to interface INetPassEnum and so on ...
what i did:

<pre lang="x-c# ...
...
[DllImport("BlNetpassApi")]
public static extern int BlNetPassCreateA(string pHostName, ref Guid GUID, out IntPtr rINetPass);

...
...

IntPtr something;
Guid temp_guid = Guid.Empty;

int temp_int = BlNetPassCreateA(null, ref temp_guid, out something);[/code]

ok! IntPtr contains some data, but whats next ... how to describe interface that is behind and call its method? ((((((((
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