Get list of computer name from network

using System;

using System.Runtime.InteropServices;

using System.Security;

using System.Collections;

using System.Windows.Forms;

namespace Mesoft.Network

{

    public sealed class NetworkBrowser

    {

        #region Dll Imports

         //declare the the Netapi32 : NetServerEnum method import

        [DllImport("Netapi32", CharSet = CharSet.Auto, SetLastError = true),

        SuppressUnmanagedCodeSecurityAttribute]

        /// <summary>

        /// Netapi32.dll : The NetServerEnum function lists all servers

        /// of the specified type that are visible in a domain. For example, an 

        /// application can call NetServerEnum to list all domain controllers only

        /// or all SQL servers only.

        ///    You can combine bit masks to list several types. For example, a value 

        /// of 0x00000003  combines the bit masks for SV_TYPE_WORKSTATION 

        /// (0x00000001) and SV_TYPE_SERVER (0x00000002)

        /// </summary>

        public static extern int NetServerEnum(

            string ServerNane, // must be null

            int dwLevel,

            ref IntPtr pBuf,

            int dwPrefMaxLen,

            out int dwEntriesRead,

            out int dwTotalEntries,

            int dwServerType,

            string domain, // null for login domain

            out int dwResumeHandle

            );

        //declare the Netapi32 : NetApiBufferFree method import

        [DllImport("Netapi32", SetLastError = true),

        SuppressUnmanagedCodeSecurityAttribute]

        /// <summary>

        /// Netapi32.dll : The NetApiBufferFree function frees 

        /// the memory that the NetApiBufferAllocate function allocates. 

        /// Call NetApiBufferFree to free the memory that other network 

        /// management functions return.

        /// </summary>

        public static extern int NetApiBufferFree(

            IntPtr pBuf);

        //create a _SERVER_INFO_100 STRUCTURE

        [StructLayout(LayoutKind.Sequential)]

        public struct _SERVER_INFO_100

        {

            internal int sv100_platform_id;

            [MarshalAs(UnmanagedType.LPWStr)]

            internal string sv100_name;

        }

        #endregion

        #region Public Constructor

        public NetworkBrowser()

        {

        }

        #endregion

        #region Public Methods

        /// <summary>

        /// Uses the DllImport : NetServerEnum with all its required parameters

        /// (see http://msdn.microsoft.com/library/default.asp?url=/library/en-us/netmgmt/netmgmt/netserverenum.asp

        /// for full details or method signature) to retrieve a list of domain SV_TYPE_WORKSTATION

        /// and SV_TYPE_SERVER PC's

        /// </summary>

        /// <returns>Arraylist that represents all the SV_TYPE_WORKSTATION and SV_TYPE_SERVER

        /// PC's in the Domain</returns>

        public ArrayList getNetworkComputers()

        {

            //local fields

            ArrayList networkComputers = new ArrayList();

            const int MAX_PREFERRED_LENGTH = -1;

            int SV_TYPE_WORKSTATION = 1;

            int SV_TYPE_SERVER = 2;

            IntPtr buffer = IntPtr.Zero;

            IntPtr tmpBuffer = IntPtr.Zero;

            int entriesRead = 0;

           int totalEntries = 0;

            int resHandle = 0;

            int sizeofINFO = Marshal.SizeOf(typeof(_SERVER_INFO_100));

            try

            {

                //call the DllImport : NetServerEnum with all its required parameters

                //see http://msdn.microsoft.com/library/default.asp?url=/library/en-us/netmgmt/netmgmt/netserverenum.asp

                //for full details of method signature

                int ret = NetServerEnum(null, 100, ref buffer, MAX_PREFERRED_LENGTH,

                    out entriesRead,

                    out totalEntries, SV_TYPE_WORKSTATION | SV_TYPE_SERVER, null, out 

                    resHandle);

              //if the returned with a NERR_Success (C++ term), =0 for C#

                if (ret == 0)

                {

                    //loop through all SV_TYPE_WORKSTATION and SV_TYPE_SERVER PC's

                    for (int i = 0; i < totalEntries; i++)

                    {

                        //get pointer to, Pointer to the buffer that received the data from

                        //the call to NetServerEnum. Must ensure to use correct size of 

                        //STRUCTURE to ensure correct location in memory is pointed to

                        tmpBuffer = new IntPtr((int)buffer + (i * sizeofINFO));

                        //Have now got a pointer to the list of SV_TYPE_WORKSTATION and 

                        //SV_TYPE_SERVER PC's, which is unmanaged memory

                        //Needs to Marshal data from an unmanaged block of memory to a 

                        //managed object, again using STRUCTURE to ensure the correct data

                        //is marshalled 

                        _SERVER_INFO_100 svrInfo = (_SERVER_INFO_100)

                            Marshal.PtrToStructure(tmpBuffer, typeof(_SERVER_INFO_100));

                        //add the PC names to the ArrayList

                        networkComputers.Add(svrInfo.sv100_name);

                    }

                }

            }

            catch (Exception ex)

            {

                MessageBox.Show("Problem with acessing network computers in NetworkBrowser " + "\r\n\r\n\r\n" + ex.Message, "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);

                return null;

            }

            finally

            {

                //The NetApiBufferFree function frees 

                //the memory that the NetApiBufferAllocate function allocates

                NetApiBufferFree(buffer);

            }

            //return entries found

            return networkComputers;

        }

        #endregion

    }

}