Visual Basic Network Services
GetAdaptersInfo: Get IP Addresses for All Installed Network Adapters
     
Posted:   Wednesday April 25, 2001
Updated:   Monday December 26, 2011
     
Applies to:   VB4-32, VB5, VB6
Developed with:   VB6, Windows 2000
OS restrictions:   Windows 98, Windows 2000, Windows XP
Author:   VBnet - Randy Birch
     

Related:  

GetAdaptersInfo: Determine if DHCP is Enabled
GetAdaptersInfo: Get the DHCP Server IP
GetAdaptersInfo: Get the IPs for all DHCP Servers
GetAdaptersInfo: Get the Network Adapter IP Address
GetAdaptersInfo: Get IP Addresses for All Installed Network Adapters

GetNetworkParams: Determine Current and Available DNS Servers
     
 Prerequisites
One of the operating systems listed under OS Restrictions above.

The IP_ADAPTER_INFO type returned from GetAdaptersInfo contains byte array representing the sIPAddress of the installed network card. By retrieving the pointer to the sIPAddress member, the local IP addresses for all installed network cards can be returned.

Note that my system uses a LinkSys DSL Router to provide both DHCP and firewall capabilities, so internally the returned addresses are all in the 192.168.1.xxx range. For clarity in the illustration I used the plus sign as a delimiter; in practice you would probably use a more conventional symbol such as a comma or a pipe.

 BAS Module Code
None.

 Form Code
To a form add a command button (Command1), and a Text box (Text1).  Add the following to the form:

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.
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
Private Const MAX_ADAPTER_NAME_LENGTH         As Long = 256
Private Const MAX_ADAPTER_DESCRIPTION_LENGTH  As Long = 128
Private Const MAX_ADAPTER_ADDRESS_LENGTH      As Long = 8
Private Const ERROR_SUCCESS  As Long = 0

Private Type IP_ADDRESS_STRING
    IpAddr(0 To 15)  As Byte
End Type

Private Type IP_MASK_STRING
    IpMask(0 To 15)  As Byte
End Type

Private Type IP_ADDR_STRING
    dwNext     As Long
    IpAddress  As IP_ADDRESS_STRING
    IpMask     As IP_MASK_STRING
    dwContext  As Long
End Type

Private Type IP_ADAPTER_INFO
  dwNext                As Long
  ComboIndex            As Long  'reserved
  sAdapterName(0 To (MAX_ADAPTER_NAME_LENGTH + 3))        As Byte
  sDescription(0 To (MAX_ADAPTER_DESCRIPTION_LENGTH + 3)) As Byte
  dwAddressLength       As Long
  sIPAddress(0 To (MAX_ADAPTER_ADDRESS_LENGTH - 1))       As Byte
  dwIndex               As Long
  uType                 As Long
  uDhcpEnabled          As Long
  CurrentIpAddress      As Long
  IpAddressList         As IP_ADDR_STRING
  GatewayList           As IP_ADDR_STRING
  DhcpServer            As IP_ADDR_STRING
  bHaveWins             As Long
  PrimaryWinsServer     As IP_ADDR_STRING
  SecondaryWinsServer   As IP_ADDR_STRING
  LeaseObtained         As Long
  LeaseExpires          As Long
End Type

Private Declare Function GetAdaptersInfo Lib "iphlpapi.dll" _
  (pTcpTable As Any, _
   pdwSize As Long) As Long
   
Private Declare Sub CopyMemory Lib "kernel32" _
   Alias "RtlMoveMemory" _
  (dst As Any, _
   src As Any, _
   ByVal bcount As Long)
   

Private Sub Command1_Click()

  'pass a character to be used as the
  'delimiter in the list of returned addresses.
   Text1.Text = LocalIPAddresses("+")


End Sub

   
Public Function LocalIPAddresses(ByVal sDelim As String) As String
   
  'api vars
   Dim cbRequired  As Long
   Dim buff()      As Byte
   Dim Adapter     As IP_ADAPTER_INFO
   Dim AdapterStr  As IP_ADDR_STRING
    
  'working vars
   Dim ptr1        As Long
   Dim sIPAddr     As String
   Dim sAllAddr    As String
   
   Call GetAdaptersInfo(ByVal 0&, cbRequired)

   If cbRequired > 0 Then
    
      ReDim buff(0 To cbRequired - 1) As Byte
      
      If GetAdaptersInfo(buff(0), cbRequired) = ERROR_SUCCESS Then
      
        'get a pointer to the data stored in buff()
         ptr1 = VarPtr(buff(0))
                  
        'ptr1 is 0 when no more adapters
         Do While (ptr1 <> 0)
         
           'copy the data from the pointer to the
           'first adapter into the IP_ADAPTER_INFO type
            CopyMemory Adapter, ByVal ptr1, LenB(Adapter)
         
            With Adapter
         
              'the DHCP IP address is in the
              'IpAddress.IpAddr member
               sIPAddr = TrimNull(StrConv(.IpAddressList.IpAddress.IpAddr, vbUnicode))
               sAllAddr = sAllAddr & sIPAddr & sDelim 
               
              'more?
               ptr1 = .dwNext
               
            End With  'With Adapter
            
         Loop  'Do While (ptr1 <> 0)

      End If  'If GetAdaptersInfo
   End If  'If cbRequired > 0

  'remove the last delimiter
   If Len(sAllAddr) > 0 Then
      sAllAddr = Left$(sAllAddr, Len(sAllAddr) - Len(sDelim))
   End If
         
  'return any string found
   LocalIPAddresses = sAllAddr
   
   
End Function


Private Function TrimNull(item As String) As String

    Dim pos As Integer
   
   'double check that there is a chr$(0) in the string
    pos = InStr(item, Chr$(0))
    If pos Then
       TrimNull = Left$(item, pos - 1)
    Else
       TrimNull = item
    End If
  
End Function
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