Exemple #1
0
        private void EndTcpReadData(IAsyncResult ar)
        {
            TcpClient     client = null;
            NetworkStream stream = null;

            try
            {
                object[] state = (object[])ar.AsyncState;
                client = (TcpClient)state[0];
                stream = (NetworkStream)state[1];
                byte[] buffer = (byte[])state[2];

                Timer timer = (Timer)state[3];
                timer.Dispose();

                stream.EndRead(ar);

                DnsMessageBase query;

                try
                {
                    query = DnsMessageBase.Create(buffer, true, TsigKeySelector, null);
                }
                catch (Exception e)
                {
                    throw new Exception("Error parsing dns query", e);
                }

                DnsMessageBase response = ProcessMessage(query, ((IPEndPoint)client.Client.RemoteEndPoint).Address, ProtocolType.Tcp);

                if (response == null)
                {
                    response         = query;
                    query.IsQuery    = false;
                    query.ReturnCode = ReturnCode.ServerFailure;
                }

                int length = response.Encode(out buffer, true);

                timer = new Timer(TcpTimedOut, new object[] { client, stream }, 120000, System.Threading.Timeout.Infinite);
                stream.BeginWrite(buffer, 0, length, EndTcpSendData, new object[] { client, stream, timer });
            }
            catch (Exception e)
            {
                try
                {
                    if (stream != null)
                    {
                        stream.Close();
                    }
                }
                catch {}

                try
                {
                    if (client != null)
                    {
                        client.Close();
                    }
                }
                catch {}

                OnExceptionThrown(e);
            }
        }
Exemple #2
0
        private void EndUdpReceive(IAsyncResult ar)
        {
            try
            {
                IPEndPoint endpoint = new IPEndPoint(IPAddress.Any, _DNS_PORT);

                byte[] buffer = _udpClient.EndReceive(ar, ref endpoint);

                DnsMessageBase query;
                try
                {
                    query = DnsMessageBase.Create(buffer, true, TsigKeySelector, null);
                }
                catch (Exception e)
                {
                    throw new Exception("Error parsing dns query", e);
                }

                DnsMessageBase response = ProcessMessage(query, endpoint.Address, ProtocolType.Udp);

                if (response == null)
                {
                    response         = query;
                    query.IsQuery    = false;
                    query.ReturnCode = ReturnCode.ServerFailure;
                }

                int length = response.Encode(out buffer, false);

                #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.UpdPayloadSize);
                    }

                    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(out buffer, false);
                            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(out buffer, false);
                            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(out buffer, false);
                            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(out buffer, false);
                            continue;
                        }
                    }
                }
                #endregion

                _udpClient.BeginSend(buffer, length, endpoint, EndUdpSend, null);
            }
            catch (Exception e)
            {
                OnExceptionThrown(e);
            }

            StartUdpListen();
        }