Callback from unmanaged to managed code

Question

I run managed code and initiate an unmanaged code call. There is a callback in unmanaged code. From unmanaged, I get a callback in my managed method "DelegateMethod". But I am not getting the correct parameter / argument values ​​from unmanaged code. Please help me with this.

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

namespace TestApp
{
    public class Program
    {
        public delegate void fPointer(byte[] Sendapdu, ref int Sendlen, byte[] Recvapdu, ref int Recvlen);

        public struct sCommsAbstraction
        {
            ///Function to send and receive.
            public fPointer pf_TxRx;

            ///Other functions if necessary, e.g. reset
        }

        // Create a method for a delegate. 
        public static void DelegateMethod(byte[] Sendapdu, ref int Sendlen, byte[] Recvapdu, ref int Recvlen)
        {
            //This is called from unmanaged code. I am not getting proper arguments
            Console.WriteLine(Sendlen);
        }

        [DllImport("AuthLibrary.dll", CallingConvention = CallingConvention.Cdecl)]
        public static extern int CmdLib_RegisterItsIO(ref sCommsAbstraction psCommsFunctions);

        [DllImport("AuthLibrary.dll", CallingConvention = CallingConvention.Cdecl)]
        public static extern int CmdLib_OpenApplication();

        [DllImport("TransparentChannel.dll", CallingConvention = CallingConvention.Cdecl)]
        public static extern int TC_Transceive(byte[] writeBuf, ref int writeBufLen, byte[] readBuf, ref int pwReadBufferLen);

        static void Main(string[] args)
        {
            sCommsAbstraction psCommsFunctions = new sCommsAbstraction();
            // Instantiate the delegate.
            psCommsFunctions.pf_TxRx = DelegateMethod;

            CmdLib_RegisterItsIO(ref psCommsFunctions);
            CmdLib_OpenApplication();
        }
    }
}

Here is my indispensable piece of code - CmdLib.c

//C code - unmanaged

typedef int32_t (*pFTransceive)(const uint8_t *prgbWriteBuffer, const uint16_t *pwWriteBufferLen, uint8_t *prgbReadBuffer, uint16_t *pwReadBufferLen);

typedef struct sCommsAbstraction
{
    ///Function to send and receive.
    pFTransceive pf_TxRx;

    ///Other functions if necessary, e.g. reset
}sCommsAbstraction_d

static sCommsAbstraction_d sCommsAbstraction = {0};

void CmdLib_RegisterItsIO(const sCommsAbstraction_d *psCommsFunctions)
{
    sCommsAbstraction.pf_TxRx = psCommsFunctions->pf_TxRx;    
}
void CmdLib_OpenApplication()
{
    sCommsAbstraction.pf_TxRx(rgbAPDUBuffer,&wTotalLength,rgbAPDUBuffer,&psApduData->wResponseLength);
}

Answer 1

Your delegate declaration does not match the function pointer declaration pFTransceive. Which creates argument values ​​for garbage in your callback method.

Come closer:

    [UnmanagedFunctionPointer(CallingConvention.Cdecl)]
    public delegate void fPointer(
        [MarshalAs(UnmanagedType.LPArray, SizeParamIndex = 1)]
        byte[] Sendapdu, ref short Sendlen,
        [MarshalAs(UnmanagedType.LPArray, SizeParamIndex = 3)]
        byte[] Recvapdu, ref short Recvlen
    );

, , C/++. uint16_t.

.

---

    sCommsAbstraction psCommsFunctions = new sCommsAbstraction();

, . , . , , , . Kaboom, . , . .

, Main():

    GC.KeepAlive(psCommsFunctions);

- , - null, , .