private DnsDatagram DnsApplicationQueryClosestDelegation(DnsDatagram request)
{
if ((_dnsApplicationManager.DnsAuthoritativeRequestHandlers.Count < 1) || (request.Question.Count != 1))
{
return(null);
}
IPEndPoint localEP = new IPEndPoint(IPAddress.Any, 0);
DnsQuestionRecord question = request.Question[0];
string currentDomain = question.Name;
while (true)
{
DnsDatagram nsRequest = new DnsDatagram(0, false, DnsOpcode.StandardQuery, false, false, true, false, false, false, DnsResponseCode.NoError, new DnsQuestionRecord[] { new DnsQuestionRecord(currentDomain, DnsResourceRecordType.NS, DnsClass.IN) });
foreach (IDnsAuthoritativeRequestHandler requestHandler in _dnsApplicationManager.DnsAuthoritativeRequestHandlers)
{
try
{
DnsDatagram nsResponse = requestHandler.ProcessRequestAsync(nsRequest, localEP, DnsTransportProtocol.Tcp, false).Sync();
if (nsResponse is not null)
{
if ((nsResponse.Answer.Count > 0) && (nsResponse.Answer[0].Type == DnsResourceRecordType.NS))
{
return(new DnsDatagram(request.Identifier, true, nsResponse.OPCODE, nsResponse.AuthoritativeAnswer, nsResponse.Truncation, nsResponse.RecursionDesired, nsResponse.RecursionAvailable, nsResponse.AuthenticData, nsResponse.CheckingDisabled, nsResponse.RCODE, request.Question, null, nsResponse.Answer, nsResponse.Additional));
}
else if ((nsResponse.Authority.Count > 0) && (nsResponse.FindFirstAuthorityType() == DnsResourceRecordType.NS))
{
return(new DnsDatagram(request.Identifier, true, nsResponse.OPCODE, nsResponse.AuthoritativeAnswer, nsResponse.Truncation, nsResponse.RecursionDesired, nsResponse.RecursionAvailable, nsResponse.AuthenticData, nsResponse.CheckingDisabled, nsResponse.RCODE, request.Question, null, nsResponse.Authority, nsResponse.Additional));
}
}
}
catch (Exception ex)
{
if (_log is not null)
{
_log.Write(ex);
}
}
}
//get parent domain
int i = currentDomain.IndexOf('.');
if (i < 0)
{
break;
}
currentDomain = currentDomain.Substring(i + 1);
}
return(null);
}
