p; '''' Holds the "best" preference number (lowest)
Dim sBestMX As String '''' Holds the "best" MX record (the one with the lowest preference)
iBestPref = -1
ParseName dnsReply(), iNdx, sTemp
'''' Step over null
iNdx = iNdx + 2
'''' Step over 6 bytes (not sure what the 6 bytes are, but all other
'''' documentation shows steping over these 6 bytes)
iNdx = iNdx + 6
On Error Resume Next
While (iAnCount)
'''' Check to make sure we received an MX record
If (dnsReply(iNdx) = 15) Then
Dim sName As String
Dim iPref As Integer
sName = ""
'''' Step over the last half of the integer that specifies the record type (1 byte)
'''' Step over the RR Type, RR Class, TTL (3 integers - 6 bytes)
iNdx = iNdx + 1 + 6
'''' Read the MX data length specifier
'''' (not needed, hence why it''''s commented out)
MemCopy iMXLen, dnsReply(iNdx), 2
iMXLen = ntohs(iMXLen)
'''' Step over the MX data length specifier (1 integer - 2 bytes)
iNdx = iNdx + 2
MemCopy iPref, dnsReply(iNdx), 2
iPref = ntohs(iPref)
'''' Step over the MX preference value (1 integer - 2 bytes)
iNdx = iNdx + 2
'''' Have to step through the byte-stream, looking for 0xc0 or 192 (compression char)
Dim iNdx2 As Integer
iNdx2 = iNdx
ParseName dnsReply(), iNdx2, sName
If (iBestPref = -1 Or iPref < iBestPref) Then
iBestPref = iPref
sBestMX = sName
End If
iNdx = iNdx + iMXLen + 1
'''' Step over 3 useless bytes
''''iNdx = iNdx + 3
Else
GetMXName = sBestMX
Exit Function
End If
iAnCount = iAnCount - 1
Wend
GetMXName = sBestMX
End Function
Public Function GetDNSinfo() As String
Dim error As Long
Dim FixedInfoSize As Long
Dim strDNS As String
Dim FixedInfo As FIXED_INFO
Dim Buffer As IP_ADDR_STRING
Dim FixedInfoBuffer() As Byte
FixedInfoSize = 0
error = GetNetworkParams(ByVal 0&, FixedInfoSize)
If error <> 0 Then
If error <> ERROR_BUFFER_OVERFLOW Then
MsgBox "GetNetworkParams sizing failed with error: " & error
Exit Function
End If
End If
ReDim FixedInfoBuffer(FixedInfoSize - 1)
error = GetNetworkParams(FixedInfoBuffer(0), FixedInfoSize)
If error = 0 Then
CopyMemory FixedInfo, FixedInfoBuffer(0), Len(FixedInfo)
strDNS = FixedInfo.DnsServerList.IpAddress
strDNS = Replace(strDNS, vbCr, "")
strDNS = Replace(strDNS, vbLf, "")
strDNS = Replace(strDNS, vbNullChar, "")
strDNS = Trim(strDNS)
GetDNSinfo = strDNS
End If
End Function
Private Sub Class_Initialize()
Set objWinSock = New MSWinsockLib.Winsock
objWinSock.Protocol = sckUDPProtocol
objWinSock.RemotePort = 53
End Sub
Private Sub Class_Terminate()
Set objWinSock = Nothing ''''
End Sub
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
''''''''class
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
Private Sub objWinSock_Error(ByVal Number As Integer, Description As String, ByVal Scode As Long, ByVal Source As String, ByVal HelpFile As String, ByVal HelpContext As Long, CancelDisplay As Boolean)
Debug.Print Description
End Sub
Private Sub objWinSock_DataArrival(ByVal bytesTotal As Long)
DNSrecieved = True
ReDim dnsReply(bytesTotal) As Byte
objWinSock.GetData dnsReply, vbArray + vbByte
End Sub
Public Function MX_Query(DNS_Addr As String, ByVal Domain_Addr As String) As String
Dim IpAddr As Long
Dim iRC As Integer
Dim dnsHead As DNS_HEADER
Dim iSock As Integer
'''' Set the DNS parameters
dnsHead.qryID = htons(&H11DF)
dnsHead.options = DNS_RECURSION
dnsHead.qdcount = htons(1)
dnsHead.ancount = 0
dnsHead.nscount = 0
dnsHead.arcount = 0
'''' Query Variables
Dim dnsQuery() As Byte
Dim sQName As String
Dim dnsQueryNdx As Integer
Dim iTemp As Integer
Dim iNdx As Integer
dnsQueryNdx = 0
ReDim dnsQuery(4000)
'''' Setup the dns structure to send the query in
'''' First goes the DNS header information
MemCopy dnsQuery(dnsQueryNdx), dnsHead, 12
dnsQueryNdx = dnsQueryNdx + 12
'''' Then the domain name (as a QNAME)
sQName = MakeQName(Domain_Addr)
iNdx = 0
While (iNdx < Len(sQName))
dnsQuery(dnsQueryNdx + iNdx) = Asc(Mid(sQName, iNdx + 1, 1))
iNdx = iNdx + 1
Wend
dnsQueryNdx = dnsQueryNdx + Len(sQName)
'''' Null terminate the string
dnsQuery(dnsQueryNdx) = &H0
dnsQueryNdx = dnsQueryNdx + 1
'''' The type of query (15 means MX query)
iTemp = htons(15)
MemCopy dnsQuery(dnsQueryNdx), iTemp, Len(iTemp)
dnsQueryNdx = dnsQueryNdx + Len(iTemp)
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