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
}
}
