public DnsResponse(IDnsResponse response)
{
header = new DnsHeader();
Questions = new List <DnsQuestion>(response.Questions);
AnswerRecords = new List <IDnsResourceRecord>(response.AnswerRecords);
AuthorityRecords = new List <IDnsResourceRecord>(response.AuthorityRecords);
AdditionalRecords = new List <IDnsResourceRecord>(response.AdditionalRecords);
header.Response = true;
Id = response.Id;
IsRecursionAvailable = response.IsRecursionAvailable;
IsAuthorativeServer = response.IsAuthorativeServer;
OperationCode = response.OperationCode;
ResponseCode = response.ResponseCode;
}
/// <summary>
/// Parses Bytes from DNS to IDnsPacket Object
/// </summary>
/// <param name="data"></param>
/// <param name="sendDnsPacket"></param>
/// <returns></returns>
public static IDnsPacket Parse(byte[] data, SendDnsPacket sendDnsPacket)
{
IDnsHeader header = DnsHeader.Parse(data.Take(12).ToArray()); //Take First 12x Bytes which should always equal to DNS header
if (header.Parameters.Response != ResponseCode.Ok) //If other response to OK, then return.
{
return(new ReceiveDnsPacket(header, sendDnsPacket.Questions, null));
}
int byteCount = 12; //Amount of bytes before answer (Start with header)
sendDnsPacket.Questions.ToList().ForEach(n => byteCount += n.ToBytes().Length); //Question Byte Count
byte[] answerArr = data.TakeLast(data.Length - byteCount).ToArray(); //Extracts answers from data
IEnumerable <IResource> answers = Resource.Parse(data, new ReceiveDnsPacket(header, sendDnsPacket.Questions, null));
return(new ReceiveDnsPacket(header, sendDnsPacket.Questions, answers));
}
/// <summary>
/// Create new header from byte reader.
/// </summary>
public static DnsHeader FromByteReader(ByteReader byteReader)
{
var header = new DnsHeader();
header.ID = byteReader.GetUshort();
header.QR = byteReader.GetBits(1);
header.OPCODE = byteReader.GetBits(4);
header.AA = byteReader.GetBits(1);
header.TC = byteReader.GetBits(1);
header.RD = byteReader.GetBits(1);
header.RA = byteReader.GetBits(1);
header.Z = byteReader.GetBits(3);
header.RCODE = byteReader.GetBits(4);
header.QDCOUNT = byteReader.GetUshort();
header.ANCOUNT = byteReader.GetUshort();
header.NSCOUNT = byteReader.GetUshort();
header.ARCOUNT = byteReader.GetUshort();
return(header);
}
private string GetCacheKey(DnsHeader header) => $"{header.Host}~{header.QueryType}~{header.QueryClass}";
private void ProcessUdpRequestAsync(object parameter)
{
object[] parameters = parameter as object[];
EndPoint remoteEP = parameters[0] as EndPoint;
DnsDatagram request = parameters[1] as DnsDatagram;
try
{
DnsDatagram response = ProcessQuery(request, remoteEP);
//send response
if (response != null)
{
byte[] sendBuffer = new byte[512];
MemoryStream sendBufferStream = new MemoryStream(sendBuffer);
try
{
response.WriteTo(sendBufferStream);
}
catch (NotSupportedException)
{
DnsHeader header = response.Header;
response = new DnsDatagram(new DnsHeader(header.Identifier, true, header.OPCODE, header.AuthoritativeAnswer, true, header.RecursionDesired, header.RecursionAvailable, header.AuthenticData, header.CheckingDisabled, header.RCODE, header.QDCOUNT, 0, 0, 0), response.Question, null, null, null);
sendBufferStream.Position = 0;
response.WriteTo(sendBufferStream);
}
//send dns datagram
_udpListener.SendTo(sendBuffer, 0, (int)sendBufferStream.Position, SocketFlags.None, remoteEP);
LogManager queryLog = _queryLog;
if (queryLog != null)
{
queryLog.Write(remoteEP as IPEndPoint, false, request, response);
}
StatsManager stats = _stats;
if (stats != null)
{
stats.Update(response, (remoteEP as IPEndPoint).Address);
}
}
}
catch (Exception ex)
{
LogManager queryLog = _queryLog;
if (queryLog != null)
{
queryLog.Write(remoteEP as IPEndPoint, false, request, null);
}
LogManager log = _log;
if (log != null)
{
log.Write(remoteEP as IPEndPoint, ex);
}
}
}
