Detect Client Computer name when an RDP session is open

Question

Hey all,

My manager has pointed out to me a few nifty things that one of our accounting applications can do because it can load different settings based on the machine name of the host and the machine name of the client when the package is opened in an RDP session.

We want to provide similar functionality in one of my company's applications.

I've found out on this site how to detect if I'm in an RDP session, but I'm having trouble finding information anywhere on how to detect the name of the client computer.

Any pointers in the right direction would be great.

I'm coding in C# for .NET 3.5

EDIT

The sample code I cobbled together from the advice below - it should be enough for anyone who has a use for the WTSQuerySessionInformation to get a feel for what's going on. Note that this isn't necessarily the best way of doing it - just a starting point that I've found useful.

When I run this locally, I get boring, expected answers. When I run it on our local office server in an RDP session, I see my own computer name in the WTSClientName property.

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

namespace TerminalServicesTest
{
    class Program
    {
        const int WTS_CURRENT_SESSION = -1;
        static readonly IntPtr WTS_CURRENT_SERVER_HANDLE = IntPtr.Zero;

        static void Main(string[] args)
        {
            StringBuilder sb = new StringBuilder();
            uint byteCount;

            foreach (WTS_INFO_CLASS item in Enum.GetValues(typeof(WTS_INFO_CLASS)))
            {
                Program.WTSQuerySessionInformation(
                    WTS_CURRENT_SERVER_HANDLE,
                    WTS_CURRENT_SESSION,
                    item,
                    out sb,
                    out byteCount);

                Console.WriteLine("{0}({1}): {2}", item.ToString(), byteCount, sb);
            }
            Console.WriteLine();
            Console.WriteLine("Press any key to exit...");
            Console.ReadKey();
        }

        [DllImport("Wtsapi32.dll")]
        public static extern bool WTSQuerySessionInformation(
            IntPtr hServer, int sessionId, WTS_INFO_CLASS wtsInfoClass, out StringBuilder ppBuffer, out uint pBytesReturned);
    }

    enum WTS_INFO_CLASS 
    {
        WTSInitialProgram = 0,
        WTSApplicationName = 1,
        WTSWorkingDirectory = 2,
        WTSOEMId = 3,
        WTSSessionId = 4,
        WTSUserName = 5,
        WTSWinStationName = 6,
        WTSDomainName = 7,
        WTSConnectState = 8,
        WTSClientBuildNumber = 9,
        WTSClientName = 10,
        WTSClientDirectory = 11,
        WTSClientProductId = 12,
        WTSClientHardwareId = 13,
        WTSClientAddress = 14,
        WTSClientDisplay = 15,
        WTSClientProtocolType = 16,
        WTSIdleTime = 17,
        WTSLogonTime = 18,
        WTSIncomingBytes = 19,
        WTSOutgoingBytes = 20,
        WTSIncomingFrames = 21,
        WTSOutgoingFrames = 22,
        WTSClientInfo = 23,
        WTSSessionInfo = 24,
        WTSSessionInfoEx = 25,
        WTSConfigInfo = 26,
        WTSValidationInfo = 27,
        WTSSessionAddressV4 = 28,
        WTSIsRemoteSession = 29
    }
}

Answer 1

Have you checked into the WTS_INFO_CLASS enum?

You can obtain this information by calling: WTSQuerySessionInformation.

I'm not sure of the exact value listed in WTS_INFO_CLASS that you need, but it looks like: WTSClientName.

Answer 2

You could also use the Cassia library for this if you don't want to deal with the P-Invokes -- the code would be:

new TerminalServicesManager().CurrentSession.ClientName