_TCPIPtoName() extremly slow, if no PTR record exists.

[rudi 18]

Hi.

Reverse lookups with _TCPIPtoName() are extreeemly slow, if there is NO PTR record (NSLOOKUP.EXE resolution returns "non existent domain")

This takes several seconds for each and every unresolvable ip address:

#include <inet.au3>

TCPStartup()

$Range="10.10.10." ; replace this with a net address your DNS server is managing PTR records for.

for $i =1 to  255
    $foo=_TCPIPtoname($Range & $i)
    if @error then $foo = "couldn't be resolved. " & @error
    ConsoleWrite($i & " = " & $foo & @CRLF)
Next

TCPShutdown()

ConsoleWrite("Done." & @CRLF)

nslookup.exe is doing the same very fast (if the DNS Server is servicing the PTR range):

set range=10.10.10.
for /l %a in (1,1,254) do (echo ---------------------- >> result.txt && nslookup %range%%a >>result.txt)

What do I miss?

Regards, Rudi.

[Authenticity 12]

expandcollapse popup

Local Const $sRange = "189.108.105."
Local $sName, $sAddress

TCPStartup()

For $i = 100 To 200
    $sAddress = $sRange & $i
    $sName = _ReverseLookup($sAddress)
    ConsoleWrite(StringFormat("\tName:  %s\n\tAddress:  %s\n", $sName, $sAddress))
Next

TCPShutdown()

Func _ReverseLookup($sIP, $iTimeout = 1000)
    Local Const $AF_INET = 2, $SOCK_DGRAM = 2, $IPPROTO_IP = 0
    Local $socket = _socket($AF_INET, $SOCK_DGRAM, $IPPROTO_IP)
    Local $tSockAddr = DllStructCreate("ushort;byte[14]"), $pSockAddr = DllStructGetPtr($tSockAddr), $iSockAddr = DllStructGetSize($tSockAddr)
    Local $sDNSServer = _GetPrimaryDnsServerAddress()

    DllStructSetData($tSockAddr, 1, $AF_INET)
    DllStructSetData($tSockAddr, 2, Binary("0x0035") & Binary(_inet_addr($sDNSServer)))
    _connect($socket, $pSockAddr, $iSockAddr)

    Local $tData = _GeneratePacket($sIP), $pData = DllStructGetPtr($tData), $iData = DllStructGetSize($tData)
    _send($socket, $pData, $iData)

    Local $tReadSockets = DllStructCreate("int;int"), $pReadSockets = DllStructGetPtr($tReadSockets)
    Local $tTimeout = DllStructCreate("int;int"), $pTimeout = DllStructGetPtr($tTimeout)

    DllStructSetData($tReadSockets, 1, 1)
    DllStructSetData($tReadSockets, 2, $socket)
    If $iTimeout < 100 Then $iTimeout = 100
    DllStructSetData($tTimeout, 1, Int($iTimeout/1000))
    DllStructSetData($tTimeout, 2, Mod($iTimeout, 1000))

    Local $iRet = _select($socket, $pReadSockets, 0, 0, $pTimeout)
    If $iRet = 0 Then
        _closesocket($socket)
        Return "DNS request timeout."
    EndIf

    Local $tRecvBuf = DllStructCreate("byte[65536]"), $pRecvBuf = DllStructGetPtr($tRecvBuf), $iRecvBuf = DllStructGetSize($tRecvBuf)
    Local $iReceived = _recv($socket, $pRecvBuf, $iRecvBuf)
    Local $xRecvData = BinaryMid(DllStructGetData($tRecvBuf, 1), 1, $iReceived)
    _closesocket($socket)

    Return _ParsePacket($xRecvData)
EndFunc


Func _socket($iaf, $itype, $iprotocol)
    Local $aResult = DllCall("wsock32.dll", "int", "socket", "int", $iaf, "int", $itype, "int", $iprotocol)

    If @error Then Return SetError(@error, @extended, 0)
    If $aResult[0] = -1 Then Return SetError(-1, 0, 0)
    Return $aResult[0]
EndFunc

Func _closesocket($socket)
    Local $aResult = DllCall("wsock32.dll", "int", "closesocket", "int", $socket)

    If @error Then Return SetError(@error, @extended, 0)
    If $aResult[0] = -1 Then Return SetError(-1, 0, 0)
    Return True
EndFunc

Func _connect($socket, $pname, $inamelen)
    Local $aResult = DllCall("wsock32.dll", "int", "connect", "int", $socket, "ptr", $pname, "int", $inamelen)

    If @error Then Return SetError(@error, @extended, 0)
    If $aResult[0] = -1 Then Return SetError(-1, 0, 0)
    Return True
EndFunc

Func _recv($socket, $pbuffer, $ibuflen, $iflags = 0)
    Local $aResult = DllCall("wsock32.dll", "int", "recv", "int", $socket, "ptr", $pbuffer, "int", $ibuflen, "int", $iflags)

    If $aResult[0] = -1 Then Return SetError(-1, 0, 0)
    Return SetError($aResult[0] = 0, 0, $aResult[0])
EndFunc

Func _send($socket, $pbuffer, $ibuflen, $iflags = 0)
    Local $aResult = DllCall("wsock32.dll", "int", "send", "int", $socket, "ptr", $pbuffer, "int", $ibuflen, "int", $iflags)

    If @error Then Return SetError(@error, @extended, 0)
    If $aResult[0] = -1 Then Return SetError(-1, 0, 0)
    Return SetError($aResult[0] = 0, 0, $aResult[0])
EndFunc

Func _select($socket, $preadfds, $pwritefds, $pexceptfds, $ptimeout)
    Local $aResult = DllCall("wsock32.dll", "int", "select", "int", $socket, "ptr", $preadfds, "ptr", $pwritefds, "ptr", $pexceptfds, "ptr", $ptimeout)

    If @error Then Return SetError(@error, @extended, 0)
    If $aResult[0] = -1 Then Return SetError(-1, 0, 0)
    Return SetError($aResult[0] = 0, 0, $aResult[0])
EndFunc

Func _inet_addr($sIP)
    Local $aResult = DllCall("wsock32.dll", "int", "inet_addr", "str", $sIP)

    If @error Then Return SetError(@error, @extended, 0)
    If $aResult[0] = -1 Then Return SetError(-1, 0, 0)
    Return SetError($aResult[0] = 0, 0, $aResult[0])
EndFunc

Func _GetPrimaryDnsServerAddress()
    Local $aResult, $tBuf, $tDnsServersList

    $aResult = DllCall("iphlpapi.dll", "uint", "GetNetworkParams", "int*", 0, "uint*", 4)

    If $aResult[0] = 111 Then
        $tBuf = DllStructCreate("byte[" & $aResult[2] & "]")
        $aResult = DllCall("iphlpapi.dll", "uint", "GetNetworkParams", "ptr", DllStructGetPtr($tBuf), "uint*", $aResult[2])
        If $aResult[0] <> 0 Then Return SetError($aResult[0], 0, "")
        $tDnsServersList = DllStructCreate("ptr;char[16];char[16];uint;", DllStructGetPtr($tBuf)+268)
        Return DllStructGetData($tDnsServersList, 2)
    Else
        Return SetError(-1, 0, "")
    EndIf
EndFunc

Func _GeneratePacket($sIP)
    Local $aParts = StringSplit($sIP, "."), $xData = Binary("0x001701000001000000000000"), $tRet

    For $i = 4 To 1 Step -1
        $xData &= Binary("0x" & Hex(StringLen($aParts[$i]), 2)) & StringToBinary($aParts[$i])
    Next

    $xData &= Binary("0x07696E2D61646472046172706100000C0001")
    $tRet = DllStructCreate("byte[" & BinaryLen($xData) & "]")
    DllStructSetData($tRet, 1, $xData)
    Return $tRet
EndFunc

Func _ParsePacket($xData)
    Local $sRet, $iErr, $iPos, $iChrs

    $iErr = BitAND(BinaryMid($xData, 4, 1), 0xf)

    If $iErr <> 0 Then
        Switch $iErr
            Case 2
                $sRet = "Server failed"
            Case 3
                $sRet = "Non-existent domain"
            Case 4
                $sRet = "Not implemented"
            Case 5
                $sRet = "Query refused"
            Case 0xf
                $sRet = "No change"
            Case Else
                $sRet = "Contact Microsoft©. Ask them what to do"
        EndSwitch
    Else
        ; Step over the "in-addr.arpa" part
        $iPos = 13
        Do
            $iPos += Number(BinaryMid($xData, $iPos, 1)) + 1
        Until Number(BinaryMid($xData, $iPos, 1)) = 0

        $iPos += 17
        $iChrs = Number(BinaryMid($xData, $iPos, 1))
        $sRet = ""

        While $iChrs
            $sRet &= BinaryToString(BinaryMid($xData, $iPos + 1, $iChrs)) & "."
            $iPos += $iChrs + 1
            $iChrs = Number(BinaryMid($xData, $iPos, 1))
        WEnd

        $sRet = StringTrimRight($sRet, 1)
    EndIf

    Return $sRet
EndFunc

Nslookup sends a packet through dgram socket on port 53, among other things.

Deciphering the sent and received packets requires more, but for now this script should do the trick.

P.S. If sending or receiving packets takes long time you can use the select function.

Edit: Added timeout option.

Edited September 18, 2010 by Authenticity

[rudi 18]

Hi.

Nslookup sends a packet through dgram socket on port 53, among other things.

Deciphering the sent and received packets requires more, but for now this script should do the trick.

Thanks , I'll be able to test it later this week, when I'm back in the office.

Regards, Rudi.

[jrsofsd 0]

Thank you Authenticity!

I'm very impressed that you would write this code in response to a question.