Question

我正在尝试编写一个用于在Windows终端服务客户端中使用虚拟通道的hello world类型程序。

public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();

    }
    IntPtr mHandle = IntPtr.Zero;
    private void Form1_Load(object sender, EventArgs e)
    {
        mHandle = NativeMethods.WTSVirtualChannelOpen(IntPtr.Zero, -1, "TSCRED");
        if (mHandle == IntPtr.Zero)
        {
            throw new Win32Exception(Marshal.GetLastWin32Error());
        }
    }

    private void button1_Click(object sender, EventArgs e)
    {
        uint bufferSize = 1024;
        StringBuilder buffer = new StringBuilder();
        uint bytesRead;
        NativeMethods.WTSVirtualChannelRead(mHandle, 0, buffer, bufferSize, out bytesRead);
        if (bytesRead == 0)
        {
            MessageBox.Show("Got no Data");
        }
        else
        {
            MessageBox.Show("Got data: " + buffer.ToString());
        }
    }

    protected override void Dispose(bool disposing)
    {
        if (mHandle != System.IntPtr.Zero)
        {
            NativeMethods.WTSVirtualChannelClose(mHandle);
        }
        base.Dispose(disposing);

    }
}

internal static class NativeMethods
{
    [DllImport("Wtsapi32.dll")]
    public static extern IntPtr WTSVirtualChannelOpen(IntPtr server,
        int sessionId, [MarshalAs(UnmanagedType.LPStr)] string virtualName);

    //[DllImport("Wtsapi32.dll", SetLastError = true)]
    //public static extern bool WTSVirtualChannelRead(IntPtr channelHandle, long timeout,
    //        byte[] buffer, int length, ref int bytesReaded);

    [DllImport("Wtsapi32.dll")]
    public static extern bool WTSVirtualChannelClose(IntPtr channelHandle);


    [DllImport("Wtsapi32.dll", EntryPoint = "WTSVirtualChannelRead")]
    [return: MarshalAs(UnmanagedType.Bool)]
    public static extern bool WTSVirtualChannelRead(
        [In()] System.IntPtr hChannelHandle
        , uint TimeOut
        , [Out()] [MarshalAs(UnmanagedType.LPStr)] 
          System.Text.StringBuilder Buffer
        , uint BufferSize
        , [Out()] out uint pBytesRead);

}

我从MSTSC COM对象和ActiveX控件发送数据。

public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();

    }

    private void Form1_Load(object sender, EventArgs e)
    {
        rdp.Server = "schamberlainvm";
        rdp.UserName = "TestAcct";
        IMsTscNonScriptable secured = (IMsTscNonScriptable)rdp.GetOcx();
        secured.ClearTextPassword = "asdf";
        rdp.CreateVirtualChannels("TSCRED");
        rdp.Connect();
    }

    private void button1_Click(object sender, EventArgs e)
    {
        rdp.SendOnVirtualChannel("TSCRED", "Hello World!");
    }
}
//Designer code
// 
// rdp
// 
this.rdp.Enabled = true;
this.rdp.Location = new System.Drawing.Point(12, 12);
this.rdp.Name = "rdp";
this.rdp.OcxState = ((System.Windows.Forms.AxHost.State)(resources.GetObject("rdp.OcxState")));
this.rdp.Size = new System.Drawing.Size(1092, 580);
this.rdp.TabIndex = 0;

~~我每次NativeMethods.WTSVirtualChannelRead运行时都会得到一个执行~~

~~对此的任何帮助将不胜感激。~~

编辑 - 当函数运行时，mHandle的值为非零值。更新了代码以添加该检查。

EDIT2 - 我使用了P/Invoke Interop Assistant并生成了一个新的sigiture

    [DllImport("Wtsapi32.dll", EntryPoint = "WTSVirtualChannelRead")]
    [return: MarshalAs(UnmanagedType.Bool)]
    public static extern bool WTSVirtualChannelRead(
        [In()] System.IntPtr hChannelHandle
        , uint TimeOut
        , [Out()] [MarshalAs(UnmanagedType.LPStr)] 
          StringBuilder Buffer
        , uint BufferSize
        , [Out()] out uint pBytesRead);

它现在收到文本字符串（是啊！）但它只获取我的测试字符串的第一个字母（Boo！）。关于出了什么问题的任何想法？

编辑3 --- 在应该读取hello world的调用之后;

BytesRead = 24

Buffer.Length = 1; Buffer.Capacity = 16; Buffer.m_StringValue =“H”;

Answer 1

问题是你在发送端发送一个16位的unicode字符串并在另一个上读出一个ansi字符串，这样编组层就会在第一个NUL字符处终止字符串缓冲区。您可以将UnmanagedType.LPStr更改为UnmanagedType.LPWStr或将其作为字节数组封送，然后使用Unicode Encoding类转换为字符串。

这样的东西可能会起作用（注意：未经测试的代码，因为我没有要测试的服务器）：

public static extern int WTSVirtualChannelRead(IntPtr hChannel, 
        uint Timeout, 
        [Out, MarshalAs(UnmanagedType.LPArray, SizeParamIndex=3)] byte[] Buffer, 
        uint BufferSize, 
        out uint BytesRead);

string DoRead(IntPtr hChannel)
{ 
    byte[] buf = new byte[1024];
    uint bytesRead;
    if (WTSVirtualChannelRead(hChannel, 0, buf, (uint)buf.Length, out bytesRead) != 0)
    {
        return Encoding.Unicode.GetString(buf, 0, (int)bytesRead);
    }
    else
    {
        return "";
    }
}

Answer 2

写这篇文章之后，我想洗个澡，但是......

private void button1_Click(object sender, EventArgs e)
{
    uint bufferSize = 2;
    StringBuilder buffer = new StringBuilder();
    StringBuilder final = new StringBuilder();
    uint bytesRead;
    NativeMethods.WTSVirtualChannelRead(mHandle, 0, buffer, bufferSize, out bytesRead);
    while (bytesRead != 0)
    {
        final.Append(buffer);
        NativeMethods.WTSVirtualChannelRead(mHandle, 0, buffer, bufferSize, out bytesRead);
    }
        MessageBox.Show("Got data: " + final.ToString());
}

如果其他人能够为唯一一个传输问题的角色提供更好的解决方案，我会很乐意接受这一点而不是这个。

WTSVirtualChannelRead仅读取字符串的第一个字母

2 个答案: