SAMPLE: Winsock.exe Getting HostAddress Using Windows Sockets (154512)

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 Download Center:

Winsock.exe

For additional information about how to download Microsoft Support files, click the following article number to view the article in the Microsoft Knowledge Base:

119591 How to Obtain Microsoft Support Files from Online Services

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MORE INFORMATION

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

Start a new project in Visual Basic. Form1 is created by default.
Place a CommandButton on the form.

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 as Integer, 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

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