把網域名稱解釋成對應的IP

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

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

Private 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

Private Declare Function gethostname Lib "WSOCK32.DLL" (ByVal szHost As String, ByVal dwHostLen As Long) As Long
Private Declare Function gethostbyname Lib "WSOCK32.DLL" (ByVal szHost As String) As Long
Private Declare Function WSAStartup Lib "WSOCK32.DLL" (ByVal wVersionRequired As Long, lpWSADATA As WSADATA) As Long
Private Declare Function WSAGetLastError Lib "WSOCK32.DLL" () As Long
Private Declare Function WSACleanup Lib "WSOCK32.DLL" () As Long
Private Declare Sub CopyMemory Lib "kernel32" Alias "RtlMoveMemory" (hpvDest As Any, ByVal hpvSource As Long, ByVal cbCopy As Long)

Private Function GetIPAddress(Optional sHost As String) As String
'返回給定機器名的Ip地址，機器名為空白時返回本機Ip地址
    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
    Dim werr        As Long

    If Not SocketsInitialize() Then
        GetIPAddress = ""
        Exit Function
    End If
   
    If sHost = "" Then
        If gethostname(sHostName, 256) = SOCKET_ERROR Then
            werr = WSAGetLastError()
            GetIPAddress = ""
            SocketsCleanup
            Exit Function
        End If

        sHostName = Trim$(sHostName)
    Else
        sHostName = Trim$(sHost) & Chr$(0)
    End If
   
    lpHost = gethostbyname(sHostName)

    If lpHost = 0 Then
        werr = WSAGetLastError()
        GetIPAddress = ""
        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

Private Function SocketsInitialize(Optional sErr As String) As Boolean
    Dim WSAD As WSADATA, sLoByte As String, sHiByte As String
    If WSAStartup(WS_VERSION_REQD, WSAD) <> ERROR_SUCCESS Then
        sErr = "The 32-bit Windows Socket is not responding."
        SocketsInitialize = False
        Exit Function
    End If

    If WSAD.wMaxSockets < MIN_SOCKETS_REQD Then
        sErr = "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))

        sErr = "Sockets version " & sLoByte & "." & sHiByte & _
                " is not supported by 32-bit Windows Sockets."

        SocketsInitialize = False
        Exit Function
    End If
    SocketsInitialize = True
End Function

Private Sub SocketsCleanup()
    If WSACleanup() <> ERROR_SUCCESS Then
        App.LogEvent "Socket error occurred in Cleanup.", vbLogEventTypeError
    End If
End Sub

Private Function HiByte(ByVal wParam As Integer)
    HiByte = wParam \ &H1 And &HFF&
End Function

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

Private Sub Command1_Click()
    On Error Resume Next
    Screen.MousePointer = vbHourglass
    txtIP.Text = GetIPAddress(txtCmpName.Text)
    Screen.MousePointer = vbDefault
End Sub