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Visual Basic Network Services NetServerEnum: Obtain Domain/Workgroup Servers and Machines |
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Posted: | Tuesday May 22, 2001 |
Updated: | Monday December 26, 2011 |
Applies to: | VB4-32, VB5, VB6 |
Developed with: | VB6, Windows 2000 |
OS restrictions: | Windows NT3.1, Windows NT4, Windows 2000, Windows XP |
Author: | VBnet - Randy Birch |
Related: |
NetServerEnum: Get Version Info for Domain/Workgroup Servers and Machines NetServerGetInfo: Configuration Info for Domain/Workgroup Servers and Machines |
Prerequisites |
One of the operating systems listed under OS Restrictions above. |
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NetServerEnum
returns, dependant on the bit mask specified, servers and/or machines that are visible on the local domain, bit masks can be combined using
Or to produce a customized listing more suitable to specific needs. No special group membership is required to successfully execute the
NetServerEnum function.
NetServerEnum, depending on the data level passed, returns only minimal information about each connected machine. Extended information for specific servers can be obtained using the WNetEnumResource function instead. The illustration shows the two machines on my local network, imaginatively named. |
BAS Module Code |
None. |
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Form Code |
To a form add a command button (Command1) and list box (List1). Add the following to the form: |
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Option Explicit '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' ' Copyright ©1996-2011 VBnet/Randy Birch, All Rights Reserved. ' Some pages may also contain other copyrights by the author. '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' ' Distribution: You can freely use this code in your own ' applications, but you may not reproduce ' or publish this code on any web site, ' online service, or distribute as source ' on any media without express permission. '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' 'Windows type used to call the Net API Private Const MAX_PREFERRED_LENGTH As Long = -1 Private Const NERR_SUCCESS As Long = 0& Private Const ERROR_MORE_DATA As Long = 234& Private Const SV_TYPE_WORKSTATION As Long = &H1 Private Const SV_TYPE_SERVER As Long = &H2 Private Const SV_TYPE_SQLSERVER As Long = &H4 Private Const SV_TYPE_DOMAIN_CTRL As Long = &H8 Private Const SV_TYPE_DOMAIN_BAKCTRL As Long = &H10 Private Const SV_TYPE_TIME_SOURCE As Long = &H20 Private Const SV_TYPE_AFP As Long = &H40 Private Const SV_TYPE_NOVELL As Long = &H80 Private Const SV_TYPE_DOMAIN_MEMBER As Long = &H100 Private Const SV_TYPE_PRINTQ_SERVER As Long = &H200 Private Const SV_TYPE_DIALIN_SERVER As Long = &H400 Private Const SV_TYPE_XENIX_SERVER As Long = &H800 Private Const SV_TYPE_SERVER_UNIX As Long = SV_TYPE_XENIX_SERVER Private Const SV_TYPE_NT As Long = &H1000 Private Const SV_TYPE_WFW As Long = &H2000 Private Const SV_TYPE_SERVER_MFPN As Long = &H4000 Private Const SV_TYPE_SERVER_NT As Long = &H8000 Private Const SV_TYPE_POTENTIAL_BROWSER As Long = &H10000 Private Const SV_TYPE_BACKUP_BROWSER As Long = &H20000 Private Const SV_TYPE_MASTER_BROWSER As Long = &H40000 Private Const SV_TYPE_DOMAIN_MASTER As Long = &H80000 Private Const SV_TYPE_SERVER_OSF As Long = &H100000 Private Const SV_TYPE_SERVER_VMS As Long = &H200000 Private Const SV_TYPE_WINDOWS As Long = &H400000 'Windows95 and above Private Const SV_TYPE_DFS As Long = &H800000 'Root of a DFS tree Private Const SV_TYPE_CLUSTER_NT As Long = &H1000000 'NT Cluster Private Const SV_TYPE_TERMINALSERVER As Long = &H2000000 'Terminal Server Private Const SV_TYPE_DCE As Long = &H10000000'IBM DSS Private Const SV_TYPE_ALTERNATE_XPORT As Long = &H20000000'rtn alternate transport Private Const SV_TYPE_LOCAL_LIST_ONLY As Long = &H40000000'rtn local only Private Const SV_TYPE_DOMAIN_ENUM As Long = &H80000000 Private Const SV_TYPE_ALL As Long = &HFFFFFFFF Private Const SV_PLATFORM_ID_OS2 As Long = 400 Private Const SV_PLATFORM_ID_NT As Long = 500 'Mask applied to svX_version_major in 'order to obtain the major version number. Private Const MAJOR_VERSION_MASK As Long = &HF Private Type SERVER_INFO_100 sv100_platform_id As Long sv100_name As Long End Type Private Declare Function NetServerEnum Lib "netapi32" _ (ByVal servername As Long, _ ByVal level As Long, _ buf As Any, _ ByVal prefmaxlen As Long, _ entriesread As Long, _ totalentries As Long, _ ByVal servertype As Long, _ ByVal domain As Long, _ resume_handle As Long) As Long Private Declare Function NetApiBufferFree Lib "netapi32" _ (ByVal Buffer As Long) As Long Private Declare Sub CopyMemory Lib "kernel32" _ Alias "RtlMoveMemory" _ (pTo As Any, uFrom As Any, _ ByVal lSize As Long) Private Declare Function lstrlenW Lib "kernel32" _ (ByVal lpString As Long) As Long Private Sub Form_Load() Command1.Caption = "Net Server Enum" End Sub Private Sub Command1_Click() Call GetServers(vbNullString) End Sub Private Function GetServers(sDomain As String) As Long 'lists all servers of the specified type 'that are visible in a domain. Dim bufptr As Long Dim dwEntriesread As Long Dim dwTotalentries As Long Dim dwResumehandle As Long Dim se100 As SERVER_INFO_100 Dim success As Long Dim nStructSize As Long Dim cnt As Long nStructSize = LenB(se100) 'Call passing MAX_PREFERRED_LENGTH to have the 'API allocate required memory for the return values. ' 'The call is enumerating all machines on the 'network (SV_TYPE_ALL); however, by Or'ing 'specific bit masks for defined types you can 'customize the returned data. For example, a 'value of 0x00000003 combines the bit masks for 'SV_TYPE_WORKSTATION (0x00000001) and 'SV_TYPE_SERVER (0x00000002). ' 'dwServerName must be Null. The level parameter '(100 here) specifies the data structure being 'used (in this case a SERVER_INFO_100 structure). ' 'The domain member is passed as Null, indicating 'machines on the primary domain are to be retrieved. 'If you decide to use this member, pass 'StrPtr("domain name"), not the string itself. success = NetServerEnum(0&, _ 100, _ bufptr, _ MAX_PREFERRED_LENGTH, _ dwEntriesread, _ dwTotalentries, _ SV_TYPE_ALL, _ 0&, _ dwResumehandle) 'if all goes well If success = NERR_SUCCESS Then 'loop through the returned data, adding each 'machine to the list For cnt = 0 To dwEntriesread - 1 'get one chunk of data and cast 'into an SERVER_INFO_100 struct 'in order to add the name to a list CopyMemory se100, ByVal bufptr + (nStructSize * cnt), nStructSize List1.AddItem GetPointerToByteStringW(se100.sv100_name) Next End If 'clean up regardless of success Call NetApiBufferFree(bufptr) 'return entries as sign of success GetServers = dwEntriesread End Function Public Function GetPointerToByteStringW(ByVal dwData As Long) As String Dim tmp() As Byte Dim tmplen As Long If dwData <> 0 Then tmplen = lstrlenW(dwData) * 2 If tmplen <> 0 Then ReDim tmp(0 To (tmplen - 1)) As Byte CopyMemory tmp(0), ByVal dwData, tmplen GetPointerToByteStringW = tmp End If End If End Function |
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Copyright ©1996-2011 VBnet and Randy Birch. All Rights Reserved. |