private void EndTcpReadData(IAsyncResult ar)
{
TcpClient client = null;
NetworkStream stream = null;
try
{
MyState state = (MyState)ar.AsyncState;
client = state.Client;
stream = state.Stream;
state.Timer.Dispose();
state.BytesToReceive -= stream.EndRead(ar);
if (state.BytesToReceive > 0)
{
if (!IsTcpClientConnected(client))
{
HandleTcpException(null, stream, client);
return;
}
state.Timer = new Timer(TcpTimedOut, state, state.TimeRemaining, System.Threading.Timeout.Infinite);
state.AsyncResult = stream.BeginRead(state.Buffer, state.Buffer.Length - state.BytesToReceive, state.BytesToReceive, EndTcpReadData, state);
}
else
{
DnsMessageBase query;
try
{
query = DnsMessageBase.CreateByFlag(state.Buffer, TsigKeySelector, null);
state.NextTsigMac = (query.TSigOptions == null) ? null : query.TSigOptions.Mac;
}
catch (Exception e)
{
throw new Exception("Error parsing dns query", e);
}
try
{
state.Response = ProcessMessage(query, ((IPEndPoint)client.Client.RemoteEndPoint).Address, ProtocolType.Tcp);
}
catch (Exception ex)
{
OnExceptionThrown(ex);
state.Response = null;
}
ProcessAndSendTcpResponse(state, false);
}
}
catch (Exception e)
{
HandleTcpException(e, stream, client);
}
}
private void ProcessAndSendTcpResponse(MyState state, bool isSubSequentResponse)
{
if (state.Response == null)
{
state.Response = DnsMessageBase.CreateByFlag(state.Buffer, TsigKeySelector, null);
state.Response.IsQuery = false;
state.Response.AdditionalRecords.Clear();
state.Response.AuthorityRecords.Clear();
state.Response.ReturnCode = ReturnCode.ServerFailure;
}
byte[] newTsigMac;
int length = state.Response.Encode(true, state.NextTsigMac, isSubSequentResponse, out state.Buffer, out newTsigMac);
if (length > 65535)
{
if ((state.Response.Questions.Count == 0) || (state.Response.Questions[0].RecordType != RecordType.Axfr))
{
OnExceptionThrown(new ArgumentException("The length of the serialized response is greater than 65,535 bytes"));
state.Response = DnsMessageBase.CreateByFlag(state.Buffer, TsigKeySelector, null);
state.Response.IsQuery = false;
state.Response.ReturnCode = ReturnCode.ServerFailure;
state.Response.AdditionalRecords.Clear();
state.Response.AuthorityRecords.Clear();
length = state.Response.Encode(true, state.NextTsigMac, isSubSequentResponse, out state.Buffer, out newTsigMac);
}
else
{
List <DnsRecordBase> nextPacketRecords = new List <DnsRecordBase>();
do
{
int lastIndex = Math.Min(500, state.Response.AnswerRecords.Count / 2);
int removeCount = state.Response.AnswerRecords.Count - lastIndex;
nextPacketRecords.InsertRange(0, state.Response.AnswerRecords.GetRange(lastIndex, removeCount));
state.Response.AnswerRecords.RemoveRange(lastIndex, removeCount);
length = state.Response.Encode(true, state.NextTsigMac, isSubSequentResponse, out state.Buffer, out newTsigMac);
} while (length > 65535);
state.Response.AnswerRecords = nextPacketRecords;
}
}
else
{
state.Response = null;
}
state.NextTsigMac = newTsigMac;
state.Timer = new Timer(TcpTimedOut, state, state.TimeRemaining, System.Threading.Timeout.Infinite);
state.AsyncResult = state.Stream.BeginWrite(state.Buffer, 0, length, EndTcpSendData, state);
}
private void EndUdpReceive(IAsyncResult ar)
{
try
{
lock (_udpListener)
{
_hasActiveUdpListener = false;
}
StartUdpListen();
IPEndPoint endpoint;
byte[] buffer = _udpListener.EndReceive(ar, out endpoint);
DnsMessageBase query;
byte[] originalMac;
try
{
query = DnsMessageBase.CreateByFlag(buffer, TsigKeySelector, null);
originalMac = (query.TSigOptions == null) ? null : query.TSigOptions.Mac;
}
catch (Exception e)
{
throw new Exception("Error parsing dns query", e);
}
DnsMessageBase response;
try
{
response = ProcessMessage(query, endpoint.Address, ProtocolType.Udp);
}
catch (Exception ex)
{
OnExceptionThrown(ex);
response = null;
}
if (response == null)
{
response = query;
query.IsQuery = false;
query.ReturnCode = ReturnCode.ServerFailure;
}
int length = response.Encode(false, originalMac, out buffer);
#region Truncating
DnsMessage message = response as DnsMessage;
if (message != null)
{
int maxLength = 512;
if (query.IsEDnsEnabled && message.IsEDnsEnabled)
{
maxLength = Math.Max(512, (int)message.EDnsOptions.UdpPayloadSize);
}
while (length > maxLength)
{
// First step: remove data from additional records except the opt record
if ((message.IsEDnsEnabled && (message.AdditionalRecords.Count > 1)) || (!message.IsEDnsEnabled && (message.AdditionalRecords.Count > 0)))
{
for (int i = message.AdditionalRecords.Count - 1; i >= 0; i--)
{
if (message.AdditionalRecords[i].RecordType != RecordType.Opt)
{
message.AdditionalRecords.RemoveAt(i);
}
}
length = message.Encode(false, originalMac, out buffer);
continue;
}
int savedLength = 0;
if (message.AuthorityRecords.Count > 0)
{
for (int i = message.AuthorityRecords.Count - 1; i >= 0; i--)
{
savedLength += message.AuthorityRecords[i].MaximumLength;
message.AuthorityRecords.RemoveAt(i);
if ((length - savedLength) < maxLength)
{
break;
}
}
message.IsTruncated = true;
length = message.Encode(false, originalMac, out buffer);
continue;
}
if (message.AnswerRecords.Count > 0)
{
for (int i = message.AnswerRecords.Count - 1; i >= 0; i--)
{
savedLength += message.AnswerRecords[i].MaximumLength;
message.AnswerRecords.RemoveAt(i);
if ((length - savedLength) < maxLength)
{
break;
}
}
message.IsTruncated = true;
length = message.Encode(false, originalMac, out buffer);
continue;
}
if (message.Questions.Count > 0)
{
for (int i = message.Questions.Count - 1; i >= 0; i--)
{
savedLength += message.Questions[i].MaximumLength;
message.Questions.RemoveAt(i);
if ((length - savedLength) < maxLength)
{
break;
}
}
message.IsTruncated = true;
length = message.Encode(false, originalMac, out buffer);
}
}
}
#endregion
_udpListener.BeginSend(buffer, 0, length, endpoint, EndUdpSend, null);
}
catch (Exception e)
{
HandleUdpException(e);
}
}
