SAMPLE: Getting HostAddress Using Windows Sockets

• Microsoft Visual Basic Professional and Enterprise Editions for Windows, version 5.0
• Microsoft Visual Basic Standard, Professional, and Enterprise Editions, 32-bit only, for Windows, version 4.0

SUMMARY

This article demonstrates how to get the HostAddress of a machine using Windows Sockets. The TCP/IP network protocol is shipped with all Windows operating systems and is becoming increasingly more important with its Internet compatibility. There is an API set for Windows Sockets that can work with TCP/IP and help to return information such as the HostName or the IP Address of a machine. This is obviously reliant on the presence of the relevant DNS or WINS servers and the TCP/IP protocol being installed. Below is a sample showing how to extract the machine HostAddress.

The following file is available for download from the Microsoft Software Library:

~ Winsock.exe

For more information about downloading files from the Microsoft Software Library, please see the following article in the Microsoft Knowledge Base:

Q119591 : How to Obtain Microsoft Support Files from Online Services

MORE INFORMATION

NOTE: This code requires at least version 1.1 of Windows Sockets.

1. Start a new project in Visual Basic. Form1 is created by default.



2. Place a CommandButton on the form.



3. Add the following code to the Form1 code window:
   

   
         Option Explicit
   
         Private Const WSADescription_Len = 256
         Private Const WSASYS_Status_Len = 128
         Private Const SOCKET_ERROR As Long = -1
   
         Private Type WSADATA
            wversion As Integer
            wHighVersion As Integer
            szDescription(0 To WSADescription_Len) As Byte
            szSystemStatus(0 To WSASYS_Status_Len) As Byte
            iMaxSockets As Integer
            iMaxUdpDg As Integer
            lpszVendorInfo As Long
         End Type
   
            Private Declare Function gethostname Lib "WSOCK32.DLL" (ByVal hostname$, _
      ByVal HostLen As Integer) As Long
   
         Private Declare Function WSAGetLastError Lib "WSOCK32.DLL" _
            () As Long
         Private Declare Function WSAStartup Lib "WSOCK32.DLL" (ByVal _
            wVersionRequired&, lpWSAData As WSADATA) As Long
         Private Declare Function WSACleanup Lib "WSOCK32.DLL" () As Long
   
         Sub Form_Load()
           Call SocketsInitialize
         End Sub
   
         Private Sub Command1_click()
           Dim hostname$, HostLen&
           HostLen& = 256
           hostname$ = Space$(HostLen&)
           If gethostname(hostname$, HostLen&) = SOCKET_ERROR Then
               MsgBox "Windows Sockets error" & Str(WSAGetLastError())
           Else
               hostname$ = Trim$(hostname$)
               hostname$ = Left$(hostname$, Len(hostname$) - 1)
               MsgBox "Host name  = " & hostname$
           End If
           SocketsCleanup
         End Sub
   
         Sub SocketsInitialize()
           Const WS_VERSION_REQD As Integer = &H101
           Const WS_VERSION_MAJOR = WS_VERSION_REQD \ &H100 And &HFF&
           Const WS_VERSION_MINOR = WS_VERSION_REQD And &HFF&
           Const MIN_SOCKETS_REQD = 1
           Dim WSAD As WSADATA
           Dim iReturn As Integer
           Dim sLowByte As String, sHighByte As String, sMsg As String
           iReturn = WSAStartup(WS_VERSION_REQD, WSAD)
           If iReturn <> 0 Then
               MsgBox "Winsock.dll is not responding."
               End
           End If
           If lobyte(WSAD.wversion) < WS_VERSION_MAJOR Or (lobyte _
             (WSAD.wversion) = WS_VERSION_MAJOR And hibyte(WSAD.wversion) _
             < WS_VERSION_MINOR) Then
             sHighByte = Trim$(Str$(hibyte(WSAD.wversion)))
             sLowByte = Trim$(Str$(lobyte(WSAD.wversion)))
             sMsg = "Windows Sockets version " & sLowByte & "." & sHighByte
             sMsg = sMsg & " is not supported by winsock.dll "
             MsgBox sMsg:
             End
        End If
        If WSAD.iMaxSockets < MIN_SOCKETS_REQD Then
          sMsg = "This application requires a minimum of "
          sMsg = sMsg & Trim$(Str$(MIN_SOCKETS_REQD)) & _
          " supported sockets."
          MsgBox sMsg
          End
        End If
         End Sub
   
         Function hibyte(ByVal wParam As Integer)
            hibyte = wParam \ &H100 And &HFF&
         End Function
   
         Function lobyte(ByVal wParam As Integer)
            lobyte = wParam And &HFF&
         End Function
   
         Sub SocketsCleanup()
           Dim lReturn As Long
           lReturn = WSACleanup()
           If lReturn <> 0 Then
             MsgBox "Socket error " & Trim$(Str$(lReturn)) & _
      " occurred in Cleanup"
             End
           End If
         End Sub
    




4. Press the F5 key to run the project. The Hostname should be printed on the form.

Additional query words:

Keywords          : kbsample kbusage kbVBp400 kbVBp500 kbhowto VB4WIN kb32bitOnly 
Version           : WINDOWS:4.0,5.0
Platform          : WINDOWS 
Issue type        : kbhowto 

Last Reviewed: May 15, 1999