Esempio n. 1
0
        /// <summary>
        /// main register responder proc for both A-EP and P2P modes
        /// in P2P mode Timestamp32S, NeighborToken32 and NeighborHMAC are verified at this time
        /// </summary>
        /// <param name="receivedFromInP2pMode">
        /// is null in A-EP mode
        /// </param>
        internal async Task AcceptRegisterRequestAsync(LocalDrpPeer acceptAt, RoutedRequest routedRequest) // engine thread
        {
            var logger = routedRequest.Logger;

            logger.ModuleName = VisionChannelModuleName_reg_responderSide;
            var req = routedRequest.RegisterReq;

            if (req.RequesterRegistrationId.Equals(acceptAt.Configuration.LocalPeerRegistrationId))
            {
                throw new InvalidOperationException();
            }

            // check  signature of requester (A)
            if (!req.RequesterSignature.Verify(_cryptoLibrary,
                                               w => req.GetSharedSignedFields(w, false),
                                               req.RequesterRegistrationId
                                               )
                )
            {
                throw new BadSignatureException("invalid REGISTER REQ RequesterSignature 2396");
            }

            if (routedRequest.ReceivedFromNeighborNullable == null)
            { // A-EP mode
                if (req.EpEndpoint.Address.Equals(acceptAt.PublicIpApiProviderResponse) == false)
                {
                    throw new PossibleAttackException();
                }
            }

            if (PendingRegisterRequestExists(req.RequesterRegistrationId))
            {
                // received duplicate REGISTER REQ packet
                logger.WriteToLog_needsAttention($"ignoring duplicate registration request {req.RequesterRegistrationId} from {routedRequest.ReceivedFromEndpoint}");
                return;
            }

            if (!RecentUniqueAcceptedRegistrationRequests.Filter(req.GetUniqueRequestIdFields))
            {
                logger.WriteToLog_needsAttention($"ignoring registration request {req.RequesterRegistrationId} ts={req.ReqTimestamp64} from {routedRequest.ReceivedFromEndpoint} with non-unique request ID fields");
                return;
            }

            logger.WriteToLog_higherLevelDetail($"accepting registration from {routedRequest.ReceivedFromEndpoint}: ReqP2pSeq16={req.ReqP2pSeq16}, NumberOfHopsRemaining={req.NumberOfHopsRemaining}, epEndpoint={req.EpEndpoint}, sourcePeer={routedRequest.ReceivedFromNeighborNullable}, ts={req.ReqTimestamp64}");

            if (!RecentUniquePublicEcdhKeys.Filter(req.RequesterEcdhePublicKey.Ecdh25519PublicKey))
            {
                logger.WriteToLog_needsAttention($"ignoring registration request {req.RequesterRegistrationId} from {routedRequest.ReceivedFromEndpoint} with non-unique RequesterEcdhePublicKey");
                return;
            }

            _pendingRegisterRequests.Add(req.RequesterRegistrationId);
            try
            {
                if (logger.WriteToLog_detail_enabled)
                {
                    logger.WriteToLog_detail($"sending NPACK to REQ to {routedRequest.ReceivedFromEndpoint} (delay={routedRequest.ReqReceivedSw_ms}ms)");
                }
                routedRequest.SendNeighborPeerAck_accepted_IfNotAlreadyReplied();

                var newConnectionToNeighbor = new ConnectionToNeighbor(this, acceptAt, ConnectedDrpPeerInitiatedBy.remotePeer, req.RequesterRegistrationId)
                {
                    LocalEndpoint = routedRequest.ReceivedFromNeighborNullable?.LocalEndpoint ?? req.EpEndpoint,
                };
                byte[] ack1UdpData;
                try
                {
                    var ack1 = new RegisterAck1Packet
                    {
                        RequesterRegistrationId = req.RequesterRegistrationId,
                        ReqTimestamp64          = req.ReqTimestamp64,
                        ResponderEcdhePublicKey = new EcdhPublicKey(newConnectionToNeighbor.LocalEcdhe25519PublicKey),
                        ResponderRegistrationId = acceptAt.Configuration.LocalPeerRegistrationId,
                        ReqP2pSeq16             = GetNewNpaSeq16_AtoEP(),
                    };
                    RecentUniquePublicEcdhKeys.AssertIsUnique(ack1.ResponderEcdhePublicKey.Ecdh25519PublicKey, $"ack1.ResponderEcdhePublicKey");
                    ack1.ToResponderTxParametersEncrypted = newConnectionToNeighbor.Encrypt_ack1_ToResponderTxParametersEncrypted_AtResponder_DeriveSharedDhSecret(logger, req, ack1, routedRequest.ReceivedFromNeighborNullable);
                    ack1.ResponderSignature = RegistrationSignature.Sign(_cryptoLibrary,
                                                                         (w2) =>
                    {
                        req.GetSharedSignedFields(w2, true);
                        ack1.GetSharedSignedFields(w2, false, true);
                    },
                                                                         acceptAt.Configuration.LocalPeerRegistrationPrivateKey);
                    if (routedRequest.ReceivedFromNeighborNullable == null)
                    {
                        ack1.RequesterEndpoint = routedRequest.ReceivedFromEndpoint;
                    }
                    ack1UdpData = ack1.Encode_OpionallySignNeighborHMAC(routedRequest.ReceivedFromNeighborNullable);

                    var    ack2Scanner = RegisterAck2Packet.GetScanner(logger, routedRequest.ReceivedFromNeighborNullable, req);
                    var    requesterVisibleDescription = routedRequest.ReceivedFromNeighborNullable?.ToString() ?? routedRequest.ReceivedFromEndpoint.ToString();
                    byte[] ack2UdpData;
                    if (routedRequest.ReceivedFromNeighborNullable == null)
                    {   // wait for ACK2, retransmitting ACK1
                        if (logger.WriteToLog_detail_enabled)
                        {
                            logger.WriteToLog_detail($"sending ACK1, waiting for ACK2");
                        }
                        ack2UdpData = await OptionallySendUdpRequestAsync_Retransmit_WaitForResponse("ack2 33469", requesterVisibleDescription, ack1UdpData, routedRequest.ReceivedFromEndpoint, ack2Scanner);
                    }
                    else
                    {   // retransmit ACK1 until NPACK (via P2P); at same time wait for ACK
                        if (logger.WriteToLog_detail_enabled)
                        {
                            logger.WriteToLog_detail($"sending ACK1, awaiting for NPACK");
                        }
                        _ = OptionallySendUdpRequestAsync_Retransmit_WaitForNeighborPeerAck("ack1 423087", ack1UdpData, routedRequest.ReceivedFromEndpoint,
                                                                                            ack1.ReqP2pSeq16, routedRequest.ReceivedFromNeighborNullable, ack1.GetSignedFieldsForNeighborHMAC);
                        // not waiting for NPACK, wait for ACK
                        if (logger.WriteToLog_detail_enabled)
                        {
                            logger.WriteToLog_detail($"waiting for ACK2");
                        }
                        ack2UdpData = await OptionallySendUdpRequestAsync_Retransmit_WaitForResponse("ack2 46051", requesterVisibleDescription, null, routedRequest.ReceivedFromEndpoint, ack2Scanner);
                    }

                    if (logger.WriteToLog_detail_enabled)
                    {
                        logger.WriteToLog_detail($"received ACK2");
                    }
                    var ack2 = RegisterAck2Packet.Decode_OptionallyVerify_InitializeP2pStreamAtResponder(logger, ack2UdpData, req, ack1, newConnectionToNeighbor);
                    if (logger.WriteToLog_detail_enabled)
                    {
                        logger.WriteToLog_detail($"verified ACK2");
                    }

                    acceptAt.AddToConnectedNeighbors(newConnectionToNeighbor, req);                                                                  // added to list here in order to respond to ping requests from A

                    SendNeighborPeerAckResponseToRegisterAck2(ack2, routedRequest.ReceivedFromEndpoint, routedRequest.ReceivedFromNeighborNullable); // send NPACK to ACK

                    _ = WaitForRegistrationConfirmationRequestAsync(requesterVisibleDescription, logger, routedRequest.ReceivedFromEndpoint, req, newConnectionToNeighbor, routedRequest.ReceivedFromNeighborNullable);

                    #region send ping, verify pong
                    var ping = newConnectionToNeighbor.CreatePing(true, false, acceptAt.ConnectedNeighborsBusySectorIds, acceptAt.AnotherNeighborToSameSectorExists(newConnectionToNeighbor));

                    var pendingPingRequest = new PendingLowLevelUdpRequest("pendingPingRequest 693", newConnectionToNeighbor.RemoteEndpoint,
                                                                           PongPacket.GetScanner(newConnectionToNeighbor.LocalNeighborToken32, ping.PingRequestId32), DateTimeNowUtc,
                                                                           Configuration.InitialPingRequests_ExpirationTimeoutS,
                                                                           ping.Encode(),
                                                                           Configuration.InitialPingRequests_InitialRetransmissionTimeoutS,
                                                                           Configuration.InitialPingRequests_RetransmissionTimeoutIncrement
                                                                           );

                    if (logger.WriteToLog_detail_enabled)
                    {
                        logger.WriteToLog_detail($"sent PING");
                    }
                    var pongPacketData = await SendUdpRequestAsync_Retransmit(pendingPingRequest); // wait for pong from A

                    if (pongPacketData == null)
                    {
                        throw new DrpTimeoutException($"reg. responder initial PING request to {newConnectionToNeighbor} (timeout={Configuration.InitialPingRequests_ExpirationTimeoutS}s)");
                    }
                    var pong = PongPacket.DecodeAndVerify(_cryptoLibrary,
                                                          pongPacketData, ping, newConnectionToNeighbor,
                                                          true);
                    if (logger.WriteToLog_detail_enabled)
                    {
                        logger.WriteToLog_detail($"verified PONG");
                    }
                    newConnectionToNeighbor.OnReceivedVerifiedPong(pong, pendingPingRequest.ResponseReceivedAtUtc.Value,
                                                                   pendingPingRequest.ResponseReceivedAtUtc.Value - pendingPingRequest.InitialTxTimeUTC.Value);
                    #endregion
                }
                catch (Exception exc)
                {
                    newConnectionToNeighbor.Dispose();
                    throw exc;
                }
            }
            catch (DrpTimeoutException exc)
            {
                logger.WriteToLog_needsAttention($"could not accept REGISTER request: {exc}");
            }
            catch (Exception exc)
            {
                logger.WriteToLog_mediumPain($"could not accept REGISTER request: {exc}");
            }
            finally
            {
                _pendingRegisterRequests.Remove(req.RequesterRegistrationId);
            }
        }
Esempio n. 2
0
        /// <returns>null if registration failed with timeout or some error code</returns>
        public async Task <ConnectionToNeighbor> RegisterAsync(LocalDrpPeer localDrpPeer, IPEndPoint epEndpoint, uint minimalDistanceToNeighbor,
                                                               byte numberofHops, double[] directionVectorNullable, bool allowConnectionsToRequesterRegistrationId) // engine thread
        {
            var regSW = Stopwatch.StartNew();

            WriteToLog_reg_requesterSide_higherLevelDetail($"connecting via EntryPeer {epEndpoint}", null, null);
            localDrpPeer.CurrentRegistrationOperationsCount++;
            try
            {
                #region PoW1
                RegisterPow1ResponsePacket pow1ResponsePacket = null;
                if (!Configuration.SandboxModeOnly_DisablePoW)
                {
                    WriteToLog_reg_requesterSide_detail($"generating PoW1 request", null, null);
                    var pow1SW = Stopwatch.StartNew();

                    await PowThreadQueue.EnqueueAsync("pow1 6318");

                    WriteToLog_reg_requesterSide_detail($"generating PoW1 request @pow thread", null, null);
                    var registerPow1RequestPacket = GenerateRegisterPow1RequestPacket(localDrpPeer.PublicIpApiProviderResponse.GetAddressBytes(), Timestamp32S);
                    await EngineThreadQueue.EnqueueAsync("pow1 234709");

                    WriteToLog_reg_requesterSide_detail($"generated PoW1 request @engine thread", null, null);

                    // send register pow1 request
                    if (pow1SW.Elapsed.TotalMilliseconds > 3000)
                    {
                        WriteToLog_reg_requesterSide_lightPain($"PoW1 took {(int)pow1SW.Elapsed.TotalMilliseconds}ms", null, null);
                    }
                    WriteToLog_reg_requesterSide_detail($"PoW1 took {(int)pow1SW.Elapsed.TotalMilliseconds}ms. sending PoW1 request", null, null);
                    var rpPow1ResponsePacketData = await SendUdpRequestAsync_Retransmit(
                        new PendingLowLevelUdpRequest("rpPow1 469", epEndpoint,
                                                      RegisterPow1ResponsePacket.GetScanner(registerPow1RequestPacket.Pow1RequestId),
                                                      DateTimeNowUtc,
                                                      Configuration.UdpLowLevelRequests_ExpirationTimeoutS,
                                                      registerPow1RequestPacket.Encode(),
                                                      Configuration.UdpLowLevelRequests_InitialRetransmissionTimeoutS,
                                                      Configuration.UdpLowLevelRequests_RetransmissionTimeoutIncrement
                                                      ));

                    //  wait for response, retransmit
                    if (rpPow1ResponsePacketData == null)
                    {
                        throw new DrpTimeoutException($"pow1 request to EP '{epEndpoint}' (timeout={Configuration.UdpLowLevelRequests_ExpirationTimeoutS}s)");
                    }
                    ;
                    pow1ResponsePacket = new RegisterPow1ResponsePacket(rpPow1ResponsePacketData);
                    WriteToLog_reg_requesterSide_detail($"got PoW1 response with status={pow1ResponsePacket.StatusCode}", null, null);
                    if (pow1ResponsePacket.StatusCode != RegisterPow1ResponseStatusCode.succeeded_Pow2Challenge)
                    {
                        throw new Pow1RejectedException(pow1ResponsePacket.StatusCode);
                    }
                }
                #endregion

                var newConnectionToNeighbor = new ConnectionToNeighbor(this, localDrpPeer, ConnectedDrpPeerInitiatedBy.localPeer, null);

                PongPacket pong;
                var        req = new RegisterRequestPacket
                {
                    RequesterRegistrationId   = localDrpPeer.Configuration.LocalPeerRegistrationId,
                    ReqTimestamp64            = Timestamp64,
                    MinimalDistanceToNeighbor = minimalDistanceToNeighbor,
                    RequesterNatBehaviour     = LocalNatBehaviour,
                    AllowConnectionsToRequesterRegistrationId = allowConnectionsToRequesterRegistrationId,
                    NumberOfHopsRemaining   = numberofHops,
                    RequesterEcdhePublicKey = new EcdhPublicKey(newConnectionToNeighbor.LocalEcdhe25519PublicKey),
                    ReqP2pSeq16             = GetNewNpaSeq16_AtoEP(),
                    EpEndpoint = epEndpoint,
                    DirectionVectorNullableD = directionVectorNullable
                };
                var logger = new Logger(this, localDrpPeer, req, VisionChannelModuleName_reg_requesterSide);
                try
                {
                    #region register REQ  PoW2
                    RecentUniquePublicEcdhKeys.AssertIsUnique(req.RequesterEcdhePublicKey.Ecdh25519PublicKey, $"req.RequesterEcdhePublicKey {req}"); // this is used in non-standard way when routing registration requests to same (local) reg. ID,  too

                    var pow2SW = Stopwatch.StartNew();
                    if (!Configuration.SandboxModeOnly_DisablePoW)
                    {
                        await PowThreadQueue.EnqueueAsync("pow2 23465");

                        if (logger.WriteToLog_detail_enabled)
                        {
                            logger.WriteToLog_detail($"calculating PoW2 @pow thread");
                        }
                        GenerateRegisterReqPow2(req, pow1ResponsePacket.ProofOfWork2Request);
                        await EngineThreadQueue.EnqueueAsync("pow2 2496");

                        if (logger.WriteToLog_detail_enabled)
                        {
                            logger.WriteToLog_detail($"calculated PoW2 @engine thread");
                        }
                    }
                    else
                    {
                        req.ProofOfWork2 = new byte[64];
                    }
                    pow2SW.Stop();
                    if (pow2SW.Elapsed.TotalMilliseconds > 3000)
                    {
                        logger.WriteToLog_lightPain($"PoW2 took {(int)pow2SW.Elapsed.TotalMilliseconds}ms");
                    }

                    req.RequesterSignature = RegistrationSignature.Sign(_cryptoLibrary,
                                                                        w => req.GetSharedSignedFields(w, false),
                                                                        localDrpPeer.Configuration.LocalPeerRegistrationPrivateKey
                                                                        );
                    var reqToAck1Stopwatch = Stopwatch.StartNew();

                    if (logger.WriteToLog_detail_enabled)
                    {
                        logger.WriteToLog_detail($"PoW2 took {(int)pow2SW.Elapsed.TotalMilliseconds}ms. sending REQ, waiting for NPACK. ReqP2pSeq16={req.ReqP2pSeq16}");
                    }
                    #endregion

                    //  var reqSW = Stopwatch.StartNew();
                    #region wait for ACK1
                    var sentRequest = new SentRequest(this, logger, epEndpoint, null, req.Encode_OptionallySignNeighborHMAC(null), req.ReqP2pSeq16, RegisterAck1Packet.GetScanner(logger, req));
                    var ack1UdpData = await sentRequest.SendRequestAsync("reg req ack1 367097");

                    var ack1 = RegisterAck1Packet.DecodeAndOptionallyVerify(logger, ack1UdpData, req, newConnectionToNeighbor);
                    if (logger.WriteToLog_detail_enabled)
                    {
                        logger.WriteToLog_detail($"verified ACK1. RequesterEndpoint={ack1.RequesterEndpoint}");
                    }
                    #endregion



                    // check if it matches to previously known local public IP
                    if (ack1.RequesterEndpoint.Address.Equals(localDrpPeer.PublicIpApiProviderResponse) == false)
                    {
                        // MITM attack / EP sent local (requester) endpoint IP some bad IP address
                        throw new PossibleAttackException();
                    }
                    RecentUniquePublicEcdhKeys.AssertIsUnique(ack1.ResponderEcdhePublicKey.Ecdh25519PublicKey, $"ack1.ResponderEcdhePublicKey from {epEndpoint}");

                    newConnectionToNeighbor.LocalEndpoint        = ack1.RequesterEndpoint;
                    newConnectionToNeighbor.RemoteRegistrationId = ack1.ResponderRegistrationId;
                    reqToAck1Stopwatch.Stop();
                    var reqToAck1TimeMs = reqToAck1Stopwatch.Elapsed.TotalMilliseconds;
                    if (logger.WriteToLog_detail_enabled)
                    {
                        logger.WriteToLog_detail($"measured  REQ-ACK1_RTT={(int)reqToAck1TimeMs}ms");
                    }

                    #region send ACK2, encode local IP
                    var ack2 = new RegisterAck2Packet
                    {
                        ReqTimestamp64          = req.ReqTimestamp64,
                        RequesterRegistrationId = localDrpPeer.Configuration.LocalPeerRegistrationId,
                        ReqP2pSeq16             = GetNewNpaSeq16_AtoEP()
                    };
                    ack2.ToRequesterTxParametersEncrypted = newConnectionToNeighbor.Encrypt_ack2_ToRequesterTxParametersEncrypted_AtRequester(logger, req, ack1, ack2);
                    newConnectionToNeighbor.InitializeP2pStream(req, ack1, ack2);
                    ack2.RequesterSignature = RegistrationSignature.Sign(_cryptoLibrary, w =>
                    {
                        req.GetSharedSignedFields(w, true);
                        ack1.GetSharedSignedFields(w, true, true);
                        ack2.GetSharedSignedFields(w, false, true);
                    },
                                                                         localDrpPeer.Configuration.LocalPeerRegistrationPrivateKey
                                                                         );

                    if (logger.WriteToLog_detail_enabled)
                    {
                        logger.WriteToLog_detail($"sending ACK2 (in response to ACK1), waiting for NPACK");
                    }
                    RespondToRequestAndRetransmissions(ack1UdpData, ack2.Encode_OptionallySignNeighborHMAC(null), epEndpoint);
                    await OptionallySendUdpRequestAsync_Retransmit_WaitForNeighborPeerAck("ack2 46873", null, epEndpoint, ack2.ReqP2pSeq16);

                    #endregion

                    var neighborWaitTimeMs = reqToAck1TimeMs * 0.5 - 250; if (neighborWaitTimeMs < 0)
                    {
                        neighborWaitTimeMs = 0;
                    }
                    if (neighborWaitTimeMs > 20)
                    {
                        if (logger.WriteToLog_detail_enabled)
                        {
                            logger.WriteToLog_detail($"awaiting {(int)neighborWaitTimeMs}ms before PING...");
                        }
                        await EngineThreadQueue.WaitAsync(TimeSpan.FromMilliseconds(neighborWaitTimeMs), "before PING 34589"); // wait until the ACK2 reaches neighbor N via peers

                        if (logger.WriteToLog_detail_enabled)
                        {
                            logger.WriteToLog_detail($"... awaiting is complete");
                        }
                    }

                    localDrpPeer.AddToConnectedNeighbors(newConnectionToNeighbor, req);

                    #region send ping request directly to neighbor N, retransmit
                    var pingRequest = newConnectionToNeighbor.CreatePing(true, false, localDrpPeer.ConnectedNeighborsBusySectorIds, localDrpPeer.AnotherNeighborToSameSectorExists(newConnectionToNeighbor));
                    newConnectionToNeighbor.InitialPendingPingRequest = new PendingLowLevelUdpRequest("pingRequest 3850", newConnectionToNeighbor.RemoteEndpoint,
                                                                                                      PongPacket.GetScanner(newConnectionToNeighbor.LocalNeighborToken32, pingRequest.PingRequestId32),
                                                                                                      DateTimeNowUtc,
                                                                                                      Configuration.InitialPingRequests_ExpirationTimeoutS,
                                                                                                      pingRequest.Encode(),
                                                                                                      Configuration.InitialPingRequests_InitialRetransmissionTimeoutS,
                                                                                                      Configuration.InitialPingRequests_RetransmissionTimeoutIncrement
                                                                                                      );

                    if (logger.WriteToLog_detail_enabled)
                    {
                        logger.WriteToLog_detail($"sending PING neighborToken32={pingRequest.NeighborToken32}, waiting for PONG");
                    }
                    var pongPacketData = await SendUdpRequestAsync_Retransmit(newConnectionToNeighbor.InitialPendingPingRequest);

                    if (pongPacketData == null)
                    {
                        throw new DrpTimeoutException($"initial reg. requester PING to {newConnectionToNeighbor} (timeout={Configuration.InitialPingRequests_ExpirationTimeoutS}s)");
                    }
                    if (newConnectionToNeighbor.IsDisposed)
                    {
                        throw new ObjectDisposedException($"initial reg. requester PING to {newConnectionToNeighbor} (special case: connection is disposed)", (Exception)null);                                     // ping timeout already destroyed the connection, so PONG response here is too late
                    }
                    pong = PongPacket.DecodeAndVerify(_cryptoLibrary,
                                                      pongPacketData, pingRequest, newConnectionToNeighbor,
                                                      true);
                    if (logger.WriteToLog_detail_enabled)
                    {
                        logger.WriteToLog_detail($"verified PONG");
                    }
                    newConnectionToNeighbor.OnReceivedVerifiedPong(pong, newConnectionToNeighbor.InitialPendingPingRequest.ResponseReceivedAtUtc.Value,
                                                                   newConnectionToNeighbor.InitialPendingPingRequest.ResponseReceivedAtUtc.Value - newConnectionToNeighbor.InitialPendingPingRequest.InitialTxTimeUTC.Value);
                    #endregion
                }
                catch
                {
                    // todo update QoS
                    newConnectionToNeighbor.Dispose(); // remove from token32 table
                    throw;
                }

                #region send registration confirmation packet to EP->X->N
                try
                {
                    var cfm = new RegisterConfirmationPacket
                    {
                        ReqTimestamp64          = req.ReqTimestamp64,
                        RequesterRegistrationId = localDrpPeer.Configuration.LocalPeerRegistrationId,
                        ResponderRegistrationConfirmationSignature = pong.ResponderRegistrationConfirmationSignature,
                        ReqP2pSeq16 = GetNewNpaSeq16_AtoEP()
                    };
                    cfm.RequesterRegistrationConfirmationSignature = RegistrationSignature.Sign(_cryptoLibrary,
                                                                                                w => newConnectionToNeighbor.GetRequesterRegistrationConfirmationSignatureFields(w, cfm.ResponderRegistrationConfirmationSignature),
                                                                                                localDrpPeer.Configuration.LocalPeerRegistrationPrivateKey);
                    if (logger.WriteToLog_detail_enabled)
                    {
                        logger.WriteToLog_detail($"sending CFM, waiting for NPACK");
                    }
                    await OptionallySendUdpRequestAsync_Retransmit_WaitForNeighborPeerAck("cfm 32107", cfm.Encode_OptionallySignNeighborHMAC(null), epEndpoint, cfm.ReqP2pSeq16);

                    if (logger.WriteToLog_detail_enabled)
                    {
                        logger.WriteToLog_detail($"received NPACK to CFM");
                    }
                }
                catch (DrpTimeoutException exc)
                {  // we ingnore exceptions here, just wite warning to log.  the connection is alive already, as direct ping channel to neighbor is set up
                    logger.WriteToLog_needsAttention($"... registration confirmation request failed: {exc}");
                }
                catch (Exception exc)
                {  // we ingnore exceptions here, just wite warning to log.  the connection is alive already, as direct ping channel to neighbor is set up
                    logger.WriteToLog_mediumPain($"... registration confirmation request failed: {exc}");
                }
                #endregion

                regSW.Stop();
                if (regSW.Elapsed.TotalMilliseconds > 5000)
                {
                    logger.WriteToLog_lightPain($"registration is completed in {(int)regSW.Elapsed.TotalMilliseconds}ms");
                }
                else
                {
                    logger.WriteToLog_higherLevelDetail($"registration is completed in {(int)regSW.Elapsed.TotalMilliseconds}ms");
                };

                return(newConnectionToNeighbor);
            }
            finally
            {
                localDrpPeer.CurrentRegistrationOperationsCount--;
            }
        }