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win API to retrieve local IP addr?

Posted on 2000-02-25
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Last Modified: 2008-03-03
I'm writing an app in VB 6.0, and need to be able to retrieve the IP address of the machine the app is running on at runtime.

We're talking to a network element via SNMP, the SNMP is done through a third-party control we purchased. Unfortunately the 3rd party ctrl has a bug and doesn't always return the right IP address (!?! don't ask).

Anyway I was wondering if anyone knew a direct windows API I could call to retrieve the local IP. thanks.
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Question by:nicholso
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LVL 9

Accepted Solution

by:
Ruchi earned 100 total points
ID: 2559454
'Module

Option Explicit

'Get Machine IP Address

'Add a module to your project (In the menu choose Project -> Add Module, Then click Open)
'Insert the following code to the module :

Public Const MAX_WSADescription = 256
Public Const MAX_WSASYSStatus = 128
Public Const ERROR_SUCCESS As Long = 0
Public Const WS_VERSION_REQD As Long = &H101
Public Const WS_VERSION_MAJOR As Long = _
WS_VERSION_REQD \ &H100 And &HFF&
Public Const WS_VERSION_MINOR As Long = WS_VERSION_REQD And &HFF&
Public Const MIN_SOCKETS_REQD As Long = 1
Public Const SOCKET_ERROR As Long = -1

Public Type HOSTENT
hName As Long
hAliases As Long
hAddrType As Integer
hLen As Integer
hAddrList As Long
End Type

Public Type WSADATA
wVersion As Integer
wHighVersion As Integer
szDescription(0 To MAX_WSADescription) As Byte
szSystemStatus(0 To MAX_WSASYSStatus) As Byte
wMaxSockets As Integer
wMaxUDPDG As Integer
dwVendorInfo As Long
End Type
Public Declare Function WSAGetLastError Lib "WSOCK32.DLL" () As Long
Public Declare Function WSAStartup Lib "WSOCK32.DLL" _
(ByVal wVersionRequired As Long, lpWSADATA As WSADATA) As Long
Public Declare Function WSACleanup Lib "WSOCK32.DLL" () As Long
Public Declare Function gethostname Lib "WSOCK32.DLL" _
(ByVal szHost As String, ByVal dwHostLen As Long) As Long
Public Declare Function gethostbyname Lib "WSOCK32.DLL" _
(ByVal szHost As String) As Long
Public Declare Sub CopyMemory Lib "kernel32" Alias "RtlMoveMemory" _
(hpvDest As Any, ByVal hpvSource As Long, ByVal cbCopy As Long)

Public Function GetIPAddress() As String
Dim sHostName As String * 256
Dim lpHost As Long
Dim HOST As HOSTENT
Dim dwIPAddr As Long
Dim tmpIPAddr() As Byte
Dim i As Integer
Dim sIPAddr As String
If Not SocketsInitialize() Then
GetIPAddress = "" 
Exit Function
End If
If gethostname(sHostName, 256) = SOCKET_ERROR Then
GetIPAddress = "" 
MsgBox "Windows Sockets error " & Str$(WSAGetLastError()) & _
" has occurred. Unable to successfully get Host Name."
SocketsCleanup
Exit Function
End If
sHostName = Trim$(sHostName)
lpHost = gethostbyname(sHostName)
If lpHost = 0 Then
GetIPAddress = "" 
MsgBox "Windows Sockets are not responding. " & _
"Unable to successfully get Host Name."
SocketsCleanup
Exit Function
End If
CopyMemory HOST, lpHost, Len(HOST)
CopyMemory dwIPAddr, HOST.hAddrList, 4
ReDim tmpIPAddr(1 To HOST.hLen)
CopyMemory tmpIPAddr(1), dwIPAddr, HOST.hLen
For i = 1 To HOST.hLen
sIPAddr = sIPAddr & tmpIPAddr(i) & "."
Next
GetIPAddress = Mid$(sIPAddr, 1, Len(sIPAddr) - 1)
SocketsCleanup
End Function

Public Function GetIPHostName() As String
Dim sHostName As String * 256
If Not SocketsInitialize() Then
GetIPHostName = "" 
Exit Function
End If
If gethostname(sHostName, 256) = SOCKET_ERROR Then
GetIPHostName = "" 
MsgBox "Windows Sockets error " & Str$(WSAGetLastError()) & _
" has occurred. Unable to successfully get Host Name."
SocketsCleanup
Exit Function
End If
GetIPHostName = Left$(sHostName, InStr(sHostName, Chr(0)) - 1)
SocketsCleanup
End Function


Public Function HiByte(ByVal wParam As Integer)
HiByte = wParam \ &H100 And &HFF&
End Function

Public Function LoByte(ByVal wParam As Integer)
LoByte = wParam And &HFF&
End Function

Public Sub SocketsCleanup()
If WSACleanup() <> ERROR_SUCCESS Then
MsgBox "Socket error occurred in Cleanup."
End If
End Sub

Public Function SocketsInitialize() As Boolean
Dim WSAD As WSADATA
Dim sLoByte As String
Dim sHiByte As String
If WSAStartup(WS_VERSION_REQD, WSAD) <> ERROR_SUCCESS Then
MsgBox "The 32-bit Windows Socket is not responding."
SocketsInitialize = False
Exit Function
End If
If WSAD.wMaxSockets < MIN_SOCKETS_REQD Then
MsgBox "This application requires a minimum of " & _
CStr(MIN_SOCKETS_REQD) & " supported sockets."
SocketsInitialize = False
Exit Function
End If
If LoByte(WSAD.wVersion) < WS_VERSION_MAJOR Or _
(LoByte(WSAD.wVersion) = WS_VERSION_MAJOR And _
HiByte(WSAD.wVersion) < WS_VERSION_MINOR) Then
sHiByte = CStr(HiByte(WSAD.wVersion))
sLoByte = CStr(LoByte(WSAD.wVersion))
MsgBox "Sockets version " & sLoByte & "." & sHiByte & _
" is not supported by 32-bit Windows Sockets."
SocketsInitialize = False
Exit Function
End If
SocketsInitialize = True
End Function


'Form

'Insert this code to your form:

Private Sub Form_Load()
MsgBox "IP Host Name: " & GetIPHostName()
MsgBox "IP Address: " & GetIPAddress()
End Sub
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Author Comment

by:nicholso
ID: 2559544
thanks a lot. Works great.
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