/// <summary> Constructs the response object based upon the data received from the DNS server. </summary>
/// <param name="responseData">The data (byte[]) from the DNS server.</param>
/// <returns>Response message object.</returns>
public DnsResponseMessage ProcessResponse(ArraySegment <byte> responseData)
{
IDnsRecordFactory factory = new DnsRecordFactory(reader);
/*
* From index 0 till 11 bytes in the responseData array, we have the header items.
*/
ushort id = reader.ReadUInt16NetworkOrder(responseData);
ushort flags = reader.ReadUInt16NetworkOrder(responseData);
ushort questionCount = reader.ReadUInt16NetworkOrder(responseData);
ushort answerCount = reader.ReadUInt16NetworkOrder(responseData);
ushort nameServerCount = reader.ReadUInt16NetworkOrder(responseData);
ushort additionalCount = reader.ReadUInt16NetworkOrder(responseData);
/*
* We have got above data, now build the response header.
*/
DnsResponseHeader header = new DnsResponseHeader(id, flags, questionCount, answerCount, additionalCount, nameServerCount);
DnsResponseMessage response = new DnsResponseMessage(header, responseData.Count);
/*
* Next item in the response data is question that we sent to the DNS server which the server has copied onto the response message.
*/
for (int questionIndex = 0; questionIndex < questionCount; questionIndex++)
{
IDnsString questionString = reader.ReadQuestionQueryString(responseData);
DnsQuestion question = new DnsQuestion(questionString, (QueryType)reader.ReadUInt16NetworkOrder(responseData), (QueryClass)reader.ReadUInt16NetworkOrder(responseData));
response.AddQuestion(question);
}
for (int answerIndex = 0; answerIndex < answerCount; answerIndex++)
{
BaseResourceRecordInfo info = factory.ReadRecordInfo(responseData);
DnsResourceRecord record = factory.GetRecord(info, responseData);
response.AddAnswer(record);
}
for (int serverIndex = 0; serverIndex < nameServerCount; serverIndex++)
{
BaseResourceRecordInfo info = factory.ReadRecordInfo(responseData);
DnsResourceRecord record = factory.GetRecord(info, responseData);
response.AddAuthority(record);
}
for (int additionalIndex = 0; additionalIndex < additionalCount; additionalIndex++)
{
BaseResourceRecordInfo info = factory.ReadRecordInfo(responseData);
DnsResourceRecord record = factory.GetRecord(info, responseData);
response.AddAdditional(record);
}
return(response);
}
public IDnsQueryResponse GetResponse()
{
var elapsed = Elapsed();
if (elapsed <= 0)
{
return(_response);
}
var response = new DnsResponseMessage(
_response.Header,
_response.MessageSize)
{
Audit = (_response as DnsQueryResponse)?.Audit ?? new LookupClientAudit()
};
foreach (var record in _response.Questions)
{
response.AddQuestion(record);
}
foreach (var record in _response.Answers)
{
var clone = record.Clone();
clone.TimeToLive = clone.TimeToLive - elapsed;
response.AddAnswer(clone);
}
foreach (var record in _response.Additionals)
{
var clone = record.Clone();
clone.TimeToLive = clone.TimeToLive - elapsed;
response.AddAnswer(clone);
}
foreach (var record in _response.Authorities)
{
var clone = record.Clone();
clone.TimeToLive = clone.TimeToLive - elapsed;
response.AddAnswer(clone);
}
var qr = response.AsQueryResponse(_response.NameServer);
return(qr);
}
