private static byte[] UpdatePacketFromCache(DnsPacket packet, ushort newId)
{
packet.UpdateTtl();
packet.UpdateTransactionId(newId);
ConsolePainter.WriteResponse($"MESSAGE FROM CACHE:\n{packet}");
return(packet.Data);
}
private byte[] GetAnswerFromBetterServer(byte[] query, Dictionary <string, DnsPacket> subCache)
{
using (var client = new UdpClient())
{
client.Client.ReceiveTimeout = 2000;
client.Send(query, query.Length, remoteDns);
byte[] response;
try
{
response = client.Receive(ref remoteDns);
}
catch (SocketException)
{
ConsolePainter.WriteWarning("Couldn't connect to the upper server. Check internet connection");
return(null);
}
var responsePacket = new DnsPacket(response);
ConsolePainter.WriteResponse($"SENDING:\n{responsePacket}");
subCache[responsePacket.Questions[0].Name] = responsePacket;
return(response);
}
}
private bool TryModifyCache(DnsPacket query, out DnsPacket cached)
{
var question = query.Questions[0];
if (cache[question.Type].TryGetValue(question.Name, out cached))
{
ConsolePainter.WriteResponse($"MESSAGE FROM CACHE:\n{cached}");
return(true);
}
if (TryFindRightCachedRecord(query, out cached))
{
var gen = DnsPacket.GenerateAnswer(query.TransactionId, query.Questions,
question.Type == ResourceType.A ? cached.AdditionalRecords : cached.AuthoritiveServers);
ConsolePainter.WriteResponse($"Modified from cache:\n{gen}");
cached = gen;
cache[query.Questions[0].Type].Add(query.Questions[0].Name, gen);
return(true);
}
cached = null;
return(false);
}