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Resolve an Internet Address to the Host Name!

Resolve an Internet Address to the Host Name!

API Declarations


wVersion As Integer
wHighVersion As Integer
szDescription As String * 257
szSystemStatus As String * 129
iMaxSockets As Long
iMaxUdpDg As Long
lpVendorInfo As Long
End Type
Public Declare Function WSAStartup Lib "wsock32.dll" (ByVal wVersionRequested As Integer, lpWSAData _
As WSADATA) As Long
Public Declare Function WSACleanup Lib "wsock32.dll" () As Long
Public Type HOSTENT
h_name As Long
h_aliases As Long
h_addrtype As Integer
h_length As Integer
h_addr_list As Long
End Type
Public Const AF_INET = 2
Public Declare Function htonl Lib "wsock32.dll" (ByVal hostlong As Long) As Long
Public Declare Function gethostbyaddr Lib "wsock32.dll" (addr As Long, ByVal length As Long, ByVal _
protocol As Long) As Long
Public Declare Sub CopyMemory Lib "kernel32.dll" Alias "RtlMoveMemory" (Destination As Any, Source _
As Any, ByVal length As Long)
Public Declare Function lstrlen Lib "kernel32.dll" Alias "lstrlenA" (ByVal lpString As Any) As Long
Public Declare Function lstrcpy Lib "kernel32.dll" Alias "lstrcpyA" (ByVal lpString1 As Any, ByVal _
lpString2 As Any) As Long

Public Const ICC_INTERNET_CLASSES = &H800
Public Declare Function CreateWindowEx Lib "user32.dll" Alias "CreateWindowExA" (ByVal dwExStyle As Long, _
ByVal lpClassName As String, ByVal lpWindowName As String, ByVal dwStyle As Long, ByVal x _
As Long, ByVal y As Long, ByVal nWidth As Long, ByVal nHeight As Long, ByVal hWndParent As Long, _
ByVal hMenu As Long, ByVal hInstance As Long, lpParam As Any) As Long
Public Const WC_IPADDRESS = "SysIPAddress32"
Public Const WS_CHILD = &H40000000
Public Const WS_VISIBLE = &H10000000
Public Declare Function DestroyWindow Lib "user32.dll" (ByVal hWnd As Long) As Long
Public Declare Function SendMessage Lib "user32.dll" Alias "SendMessageA" (ByVal hWnd As Long, ByVal Msg _
As Long, wParam As Any, lParam As Any) As Long
Public Const IPM_ISBLANK = &H469
Public Const IPM_GETADDRESS = &H466



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'and a text box named "Text1"
Private Sub cmdGetDomain_Click()
    MsgBox (ReturnHostName(Text1.Text))
End Sub

Private Function MakeLongOfInternetAddress(ByVal sIP As String) As Long

    Dim sFirst As String
    Dim sSecond As String
    Dim sThird As String
    Dim sForth As String
    Dim sAddress() As String
    
    'create an array by splitting the address by "."
    sAddress = Split(Trim(sIP), ".")
        
    'Get the hex of the number
    sFirst = Hex$(CLng(sAddress(0)))
    'make a 8-bit number by placing any 0's in front of the returned hex
    sFirst = String$(2 - Len(sFirst), "0") & sFirst
    'repeat
    sSecond = Hex$(CLng(sAddress(1)))
    sSecond = String$(2 - Len(sSecond), "0") & sSecond
    sThird = Hex$(CLng(sAddress(2)))
    sThird = String$(2 - Len(sThird), "0") & sThird
    sForth = Hex$(CLng(sAddress(3)))
    sForth = String$(2 - Len(sForth), "0") & sForth
    
    MakeLongOfInternetAddress = CLng("&H" & sFirst & sSecond & sThird & sForth)
   
End Function



Private Function ReturnHostName(ByVal sIP As String) As String
    Dim ipAddress_h As Long   ' the IP address, in host byte order
    Dim ipAddress_n As Long   ' the IP address, in network byte order
    Dim sockinfo As WSADATA   ' information about the Winsock implementation
    Dim pHostinfo As Long     ' pointer to information about the host computer
    Dim hostinfo As HOSTENT   ' information about the host computer
    Dim domainName As String  ' the primary domain name of the host computer
    Dim retval As Long        ' generic return value
    
    ipAddress_h = MakeLongOfInternetAddress(sIP)
    ' Open up a Winsock v2.2 session.
    retval = WSAStartup(&H202, sockinfo)
    If retval <> 0 Then
        Debug.Print "ERROR: Attempt to open Winsock failed: error"; retval
        Exit Function
    End If
    
    ' Convert the IP address into network byte order.
    ipAddress_n = htonl(ipAddress_h)
    ' Get information about the host computer.
    pHostinfo = gethostbyaddr(ipAddress_n, 4, AF_INET)
    If pHostinfo = 0 Then
        Debug.Print "Could not find a host with the specified IP address."
    Else
        ' Copy the data into the structure.
        CopyMemory hostinfo, ByVal pHostinfo, Len(hostinfo)
        ' Copy the host domain name into a string.
        domainName = Space(lstrlen(hostinfo.h_name))
        retval = lstrcpy(domainName, hostinfo.h_name)
    End If
    
    ReturnHostName = domainName
    ' End the Winsock session.
    retval = WSACleanup()
End Function