C# 封送 C++ 函数

Question

我正在尝试使用海康威视SDK https://www.hikvision.com/en/support/download/sdk/ 我目前的目标是用对讲室外机开门（触发输出）

我成功登录（NET_DVR_LoginV40）并显示室外站的摄像头。

我的下一步是开门。为此，我需要调用 NET_DVR_RemoteControl 函数，传入 NET_DVR_Control_GateWay.

的结构。

现在这样做时它不起作用 returns 错误 17 显然是：

Parameter error. Input or output parameters in the SDK API is NULL, or the value or format of the parameters does not match with the requirement.

所以我的 C# 代码中几乎 100% 有问题。但我不知道它是什么，据我所知，如果你不是这方面的专家（我不是），这是不可能轻易查明的

函数的dll导入：

[DllImport(@"..\bin\HCNetSDK.dll")]
public static extern bool NET_DVR_RemoteControl(int lUserID, uint dwCommand, IntPtr lpInBuffer, uint dwInBufferSize);

上一个函数的参数结构体：

 [StructLayoutAttribute(LayoutKind.Sequential)]
        public struct NET_DVR_Control_GateWay
        {
            public uint dwSize;
            public uint dwGatewayIndex;
            public byte byCommand;
            public byte byLockType;
            public UInt16 wLockID;
            [MarshalAsAttribute(UnmanagedType.ByValArray, SizeConst = 32, ArraySubType = UnmanagedType.I1)]
            public byte[] byControlSrc;
            public byte byControlType;
            [MarshalAsAttribute(UnmanagedType.ByValArray, SizeConst = 3, ArraySubType = UnmanagedType.I1)]
            public byte[] byRes3;
            [MarshalAsAttribute(UnmanagedType.ByValArray, SizeConst = 16, ArraySubType = UnmanagedType.I1)]
            public byte[] byPassword;
            [MarshalAsAttribute(UnmanagedType.ByValArray, SizeConst = 108, ArraySubType = UnmanagedType.I1)]
            public byte[] byRes2;
            public void Init()
            {
                byRes3 = new byte[64];
                byRes2 = new byte[108];
            }
        }

我的开门方法：

 private void button_Door1_Click(object sender, EventArgs e)
        {
            CHCNetSDK.NET_DVR_Control_GateWay gateWay = new CHCNetSDK.NET_DVR_Control_GateWay();
            gateWay.Init();
            gateWay.dwSize = (uint)Marshal.SizeOf(gateWay);
            gateWay.dwGatewayIndex = 1;
            gateWay.byCommand =1; //opening command
            gateWay.byLockType =  0 ; //this is a normal lock not a smart lock
            gateWay.wLockID = 0; //this is 0 because I want to use the door station's output
            gateWay.byControlSrc =  new byte[] {123} ; // this needs to be something, but doesn't matter what
            gateWay.byControlType =  1 ; //this needs to be 1 or 2 but does not matter which
            //gateWay.byPassword = ; this is not needed because the LockType is 0
            IntPtr ptrStruData = Marshal.AllocHGlobal((int)gateWay.dwSize);
            var dd = CHCNetSDK.NET_DVR_RemoteControl(lUserID, 16009, ptrStruData, gateWay.dwSize);
           
            MessageBox.Show(dd.ToString() + CHCNetSDK.NET_DVR_GetLastError().ToString() + "\n" + gateWay.dwSize.ToString() + "\n" + "ptrStruData:" + ptrStruData.ToString());
        }

According to the documentation the function looks like this

And the struct is defined as such

据我所知，我已经正确地完成了定义和导入。

如果有人能为我指明正确的方向，我将不胜感激，因为我之前从未使用过 C#、C++ 互操作，此时我不知道如何前进，如何调试，如何确定我的代码中的问题。

我已尝试就此问题联系制造商，但他们无法直接帮助我的代码，从他们的角度来看，一切正常，因为我得到的错误是我造成的问题。

非常感谢您的帮助！

Answer 1

您使用 Marshal.AllocHGlobal 分配了一些内存，您没有将 gateWay 结构复制到该内存中，而是将指向已分配内存的指针传递给 NET_DVR_RemoteControl，以便它看到 random garbage，然后你不释放分配的内存，这样它就会泄漏。

您可以在通话后 copying gateWay into the allocated memory and then freeing 修复它。

然而，最好让编组器完成它的工作：

[DllImport(HIKVISION_LIBRARY, CallingConvention = CallingConvention.StdCall, CharSet = CharSet.Ansi, ExactSpelling = true, SetLastError = false)]
[return: MarshalAs(UnmanagedType.Bool)]
public static extern bool NET_DVR_RemoteControl(int lUserID, int dwCommand, [In] ref NET_DVR_CONTROL_GATEWAY lpInBuffer, int dwInBufferSize);

[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi, Pack = 1)]
public struct NET_DVR_CONTROL_GATEWAY
{
    public int dwSize;
    public int dwGatewayIndex;
    public byte byCommand;
    public byte byLockType;
    public short wLockID;

    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = NAME_LEN)]
    public string byControlSrc;

    public byte byControlType;

    [MarshalAs(UnmanagedType.ByValArray, SizeConst = 3)]
    public byte[] byRes3;

    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = PASSWD_LEN)]
    public string byPassword;

    [MarshalAs(UnmanagedType.ByValArray, SizeConst = 108)]
    public byte[] byRes2;
}

var gateWay = new NET_DVR_CONTROL_GATEWAY()
{
    dwSize = Marshal.SizeOf<NET_DVR_CONTROL_GATEWAY>(),
    dwGatewayIndex = 1,
    byCommand = 1,
    byLockType = 0,
    wLockID = 0,
    byControlType = 1
};

var dd = NET_DVR_RemoteControl(lUserID, 16009, ref gateWay, gateWay.dwSize);

C# 封送 C++ 函数

C# marshaling C++ functions

c#

c++

struct

marshalling

hikvision