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Visual Basic Network Services gethostbyaddr: Obtain Host Name from IP Address |
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Posted: | Wed May 03, 2000 | |
Updated: | Monday December 26, 2011 | |
Applies to: | VB4-32, VB5, VB6 | |
Developed with: | VB6, Windows NT4 | |
OS restrictions: | None | |
Author: | VBnet - Randy Birch | |
Related: |
Netbios: Determine Local Adapter MAC Address SendARP: Determine Local or Remote Adapter MAC Addresses gethostbyname: Determine Network Host Name and IP Address Netbios: Determine Local Adapter MAC Addresses through LANA Enumeration gethostbyaddr: Obtain Host Name from IP Address IcmpSendEcho: Ping a Machine by IP Address IcmpSendEcho: Ping a Machine by Host Name URLDownloadToFile: Obtain Machine's Public IP Behind Router IcmpSendEcho: Perform a Tracert (Trace Route) in VB with Host Name Resolution |
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Prerequisites |
Network or DUN connection. |
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Simple function that takes an IP address and returns the host name. You will want to code additional checks to assure that the string passed is a numeric IP. |
BAS Module Code |
None. |
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Form Code |
To a form add a command button (Command1) and two text boxes (Text1 and Text2), along with the following one-liner: |
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Option Explicit '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' ' Copyright ©1996-2011 VBnet/Randy Birch, All Rights Reserved. ' Some pages may also contain other copyrights by the author. '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' ' Distribution: You can freely use this code in your own ' applications, but you may not reproduce ' or publish this code on any web site, ' online service, or distribute as source ' on any media without express permission. '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' Private Const WSADescription_Len As Long = 256 Private Const WSASYS_Status_Len As Long = 128 Private Const WS_VERSION_REQD As Long = &H101 Private Const IP_SUCCESS As Long = 0 Private Const SOCKET_ERROR As Long = -1 Private Const AF_INET As Long = 2 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 imaxudp As Integer lpszvenderinfo As Long End Type Private Declare Function WSAStartup Lib "wsock32" _ (ByVal VersionReq As Long, _ WSADataReturn As WSADATA) As Long Private Declare Function WSACleanup Lib "wsock32" () As Long Private Declare Function inet_addr Lib "wsock32" _ (ByVal s As String) As Long Private Declare Function gethostbyaddr Lib "wsock32" _ (haddr As Long, _ ByVal hnlen As Long, _ ByVal addrtype As Long) As Long Private Declare Sub CopyMemory Lib "kernel32" _ Alias "RtlMoveMemory" _ (xDest As Any, _ xSource As Any, _ ByVal nbytes As Long) Private Declare Function lstrlen Lib "kernel32" _ Alias "lstrlenA" _ (lpString As Any) As Long Private Sub Command1_Click() Text2.Text = GetHostNameFromIP(Text1.Text) End Sub Private Function SocketsInitialize() As Boolean Dim WSAD As WSADATA SocketsInitialize = WSAStartup(WS_VERSION_REQD, WSAD) = IP_SUCCESS End Function Private Sub SocketsCleanup() If WSACleanup() <> 0 Then MsgBox "Windows Sockets error occurred in Cleanup.", vbExclamation End If End Sub Private Function GetHostNameFromIP(ByVal sAddress As String) As String Dim ptrHosent As Long Dim hAddress As Long Dim nbytes As Long If SocketsInitialize() Then 'convert string address to long hAddress = inet_addr(sAddress) If hAddress <> SOCKET_ERROR Then 'obtain a pointer to the HOSTENT structure 'that contains the name and address 'corresponding to the given network address. ptrHosent = gethostbyaddr(hAddress, 4, AF_INET) If ptrHosent <> 0 Then 'convert address and 'get resolved hostname CopyMemory ptrHosent, ByVal ptrHosent, 4 nbytes = lstrlen(ByVal ptrHosent) If nbytes > 0 Then sAddress = Space$(nbytes) CopyMemory ByVal sAddress, ByVal ptrHosent, nbytes GetHostNameFromIP = sAddress End If Else MsgBox "Call to gethostbyaddr failed." End If 'If ptrHosent SocketsCleanup Else MsgBox "String passed is an invalid IP." End If 'If hAddress Else MsgBox "Sockets failed to initialize." End If 'If SocketsInitialize End Function |
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Copyright ©1996-2011 VBnet and Randy Birch. All Rights Reserved. |