AdapterList

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Introduction

NetCfgTest uses the DDK interface INetCfg and related interfaces to fetch a network adapter list (installed on the system). This article describes:

1. How to write interop code for pure COM interfaces.
2. How to use INetCfg in C# to fetch installed network adapters.
3. How to initialize a pure COM class from C#.

Background

There was a requirement to use the interface INetCfg in C#. I struggled to get a COM interop for this interface. Finally, I decided to write one.

Using the Code

The interface INetCfg is written in the namespace NetCfg. We can use the following source code to fetch an adapters list.:

object objINetCfg = null;
int nRet = 0;
nRet = Ole32Methods.CoCreateInstance(ref INetCfg_Guid.CLSID_CNetCfg, null,
    Ole32Methods.CLSCTX_INPROC_SERVER, ref INetCfg_Guid.IID_INetCfg, out objINetCfg);
INetCfg netCfg = objINetCfg as INetCfg;
nRet = netCfg.Initialize(IntPtr.Zero);
object componet = new object();
nRet = netCfg.QueryNetCfgClass(ref INetCfg_Guid.IID_DevClassNet,
    ref INetCfg_Guid.IID_INetCfgClass, out componet);
INetCfgClass NetCfgClass = componet as INetCfgClass;
object EnumNetCfgComponentObj = new object();
nRet = NetCfgClass.EnumComponents(out EnumNetCfgComponentObj);

IEnumNetCfgComponent EnumNetCfgComponent =
    EnumNetCfgComponentObj as IEnumNetCfgComponent;
EnumNetCfgComponent.Reset();
object netCfgCompObj = new object();
INetCfgComponent netcfgcomp = null;
int outCelt = 0;
nRet = EnumNetCfgComponent.Next(1, out netCfgCompObj, out outCelt);
netcfgcomp = netCfgCompObj as INetCfgComponent;
string strBind;
string strDispName = "";
do
{
    netcfgcomp.GetBindName(out strBind);
    netcfgcomp.GetDisplayName(out strDispName);
    System.Runtime.InteropServices.Marshal.ReleaseComObject(netcfgcomp);
    netCfgCompObj = null;
    this.listBox1.Items.Add(strDispName+" - " + strBind);
    nRet = EnumNetCfgComponent.Next(1, out netCfgCompObj, out outCelt);
    netcfgcomp = netCfgCompObj as INetCfgComponent;
    GC.Collect();
} while (nRet == 0);

System.Runtime.InteropServices.Marshal.ReleaseComObject(EnumNetCfgComponent);
EnumNetCfgComponent = null;
System.Runtime.InteropServices.Marshal.ReleaseComObject(objINetCfg);
objINetCfg = null;
GC.Collect();

Points of Interest

I wrote interop for a pure COM interface for the first time. It was really interesting to learn the nitty-gritty of how to use a pure COM interface in C#.

History

• Sep. 26, 2008: Created version 1.0.