Esempio n. 1
0
        private IReadOnlyList <DnsResourceRecord> GetAnswers(string domain, DnsQuestionRecord question, string zoneName, uint appRecordTtl, string healthCheck)
        {
            HealthCheckStatus status = _healthMonitor.QueryStatus(domain, question.Type, healthCheck, true);

            if (status is null)
            {
                if (question.Name.Equals(zoneName, StringComparison.OrdinalIgnoreCase)) //check for zone apex
                {
                    return new DnsResourceRecord[] { new DnsResourceRecord(question.Name, DnsResourceRecordType.ANAME, DnsClass.IN, 30, new DnsANAMERecord(domain)) }
                }
                ;                                                                                                                                                      //use ANAME
                else
                {
                    return new DnsResourceRecord[] { new DnsResourceRecord(question.Name, DnsResourceRecordType.CNAME, DnsClass.IN, 30, new DnsCNAMERecord(domain)) }
                };
            }
            else if (status.IsHealthy)
            {
                if (question.Name.Equals(zoneName, StringComparison.OrdinalIgnoreCase)) //check for zone apex
                {
                    return new DnsResourceRecord[] { new DnsResourceRecord(question.Name, DnsResourceRecordType.ANAME, DnsClass.IN, appRecordTtl, new DnsANAMERecord(domain)) }
                }
                ;                                                                                                                                                                //use ANAME
                else
                {
                    return new DnsResourceRecord[] { new DnsResourceRecord(question.Name, DnsResourceRecordType.CNAME, DnsClass.IN, appRecordTtl, new DnsCNAMERecord(domain)) }
                };
            }

            return(null);
        }
Esempio n. 2
0
        private void GetStatusAnswers(dynamic jsonAddresses, bool primary, DnsQuestionRecord question, uint appRecordTtl, string healthCheck, List <DnsResourceRecord> answers)
        {
            if (jsonAddresses == null)
            {
                return;
            }

            foreach (dynamic jsonAddress in jsonAddresses)
            {
                IPAddress         address = IPAddress.Parse(jsonAddress.Value);
                HealthCheckStatus status  = _healthMonitor.QueryStatus(address, healthCheck, false);

                string text = "app=failover; addressType=" + (primary ? "primary" : "secondary") + "; address=" + address.ToString() + "; healthCheck=" + healthCheck;

                if (status is null)
                {
                    text += "; healthStatus=Unknown;";
                }
                else if (status.IsHealthy)
                {
                    text += "; healthStatus=Healthy;";
                }
                else
                {
                    text += "; healthStatus=Failed; failureReason=" + status.FailureReason + ";";
                }

                answers.Add(new DnsResourceRecord(question.Name, DnsResourceRecordType.TXT, question.Class, appRecordTtl, new DnsTXTRecord(text)));
            }
        }
Esempio n. 3
0
        private void GetAnswers(dynamic jsonAddresses, DnsQuestionRecord question, uint appRecordTtl, string healthCheck, List <DnsResourceRecord> answers)
        {
            if (jsonAddresses == null)
            {
                return;
            }

            switch (question.Type)
            {
            case DnsResourceRecordType.A:
                foreach (dynamic jsonAddress in jsonAddresses)
                {
                    IPAddress address = IPAddress.Parse(jsonAddress.Value);

                    if (address.AddressFamily == AddressFamily.InterNetwork)
                    {
                        HealthCheckStatus status = _healthMonitor.QueryStatus(address, healthCheck, true);
                        if (status is null)
                        {
                            answers.Add(new DnsResourceRecord(question.Name, DnsResourceRecordType.A, question.Class, 30, new DnsARecord(address)));
                        }
                        else if (status.IsHealthy)
                        {
                            answers.Add(new DnsResourceRecord(question.Name, DnsResourceRecordType.A, question.Class, appRecordTtl, new DnsARecord(address)));
                        }
                    }
                }
                break;

            case DnsResourceRecordType.AAAA:
                foreach (dynamic jsonAddress in jsonAddresses)
                {
                    IPAddress address = IPAddress.Parse(jsonAddress.Value);

                    if (address.AddressFamily == AddressFamily.InterNetworkV6)
                    {
                        HealthCheckStatus status = _healthMonitor.QueryStatus(address, healthCheck, true);
                        if (status is null)
                        {
                            answers.Add(new DnsResourceRecord(question.Name, DnsResourceRecordType.AAAA, question.Class, 30, new DnsAAAARecord(address)));
                        }
                        else if (status.IsHealthy)
                        {
                            answers.Add(new DnsResourceRecord(question.Name, DnsResourceRecordType.AAAA, question.Class, appRecordTtl, new DnsAAAARecord(address)));
                        }
                    }
                }
                break;
            }
        }
Esempio n. 4
0
        public Task SendAlertAsync(IPAddress address, string healthCheck, HealthCheckStatus healthCheckStatus)
        {
            if (!_enabled || (_mailFrom is null) || (_alertTo is null) || (_alertTo.Length == 0))
            {
                return(Task.CompletedTask);
            }

            MailMessage message = new MailMessage();

            message.From = _mailFrom;

            foreach (MailAddress alertTo in _alertTo)
            {
                message.To.Add(alertTo);
            }

            if (healthCheckStatus.IsHealthy)
            {
                message.Subject = "[Alert] Address [" + address.ToString() + "] Status Is Healthy";
                message.Body    = @"Hi,

The DNS Failover App was successfully able to perform a health check [" + healthCheck + "] on the address [" + address.ToString() + @"] and found that the address was healthy.

Alert time: " + healthCheckStatus.DateTime.ToLongDateString() + @"

Regards,
DNS Failover App
";
            }
            else
            {
                message.Subject = "[Alert] Address [" + address.ToString() + "] Status Is Failed";
                message.Body    = @"Hi,

The DNS Failover App was successfully able to perform a health check [" + healthCheck + "] on the address [" + address.ToString() + @"] and found that the address failed to respond. 

The failure reason is: " + healthCheckStatus.FailureReason + @"
Alert time: " + healthCheckStatus.DateTime.ToLongDateString() + @"

Regards,
DNS Failover App
";
            }

            return(SendMailAsync(message));
        }
Esempio n. 5
0
        private void GetStatusAnswers(string domain, bool primary, DnsQuestionRecord question, uint appRecordTtl, string healthCheck, List <DnsResourceRecord> answers)
        {
            {
                HealthCheckStatus status = _healthMonitor.QueryStatus(domain, DnsResourceRecordType.A, healthCheck, false);

                string text = "app=failover; cnameType=" + (primary ? "primary" : "secondary") + "; domain=" + domain + "; qType: A; healthCheck=" + healthCheck;

                if (status is null)
                {
                    text += "; healthStatus=Unknown;";
                }
                else if (status.IsHealthy)
                {
                    text += "; healthStatus=Healthy;";
                }
                else
                {
                    text += "; healthStatus=Failed; failureReason=" + status.FailureReason + ";";
                }

                answers.Add(new DnsResourceRecord(question.Name, DnsResourceRecordType.TXT, question.Class, appRecordTtl, new DnsTXTRecord(text)));
            }

            {
                HealthCheckStatus status = _healthMonitor.QueryStatus(domain, DnsResourceRecordType.AAAA, healthCheck, false);

                string text = "app=failover; cnameType=" + (primary ? "primary" : "secondary") + "; domain=" + domain + "; qType: AAAA; healthCheck=" + healthCheck;

                if (status is null)
                {
                    text += "; healthStatus=Unknown;";
                }
                else if (status.IsHealthy)
                {
                    text += "; healthStatus=Healthy;";
                }
                else
                {
                    text += "; healthStatus=Failed; failureReason=" + status.FailureReason + ";";
                }

                answers.Add(new DnsResourceRecord(question.Name, DnsResourceRecordType.TXT, question.Class, appRecordTtl, new DnsTXTRecord(text)));
            }
        }
Esempio n. 6
0
        public Task CallAsync(IPAddress address, string healthCheck, HealthCheckStatus healthCheckStatus)
        {
            if (!_enabled)
            {
                return(Task.CompletedTask);
            }

            HttpContent content;

            {
                using (MemoryStream mS = new MemoryStream())
                {
                    JsonTextWriter jsonWriter = new JsonTextWriter(new StreamWriter(mS));
                    jsonWriter.WriteStartObject();

                    jsonWriter.WritePropertyName("address");
                    jsonWriter.WriteValue(address.ToString());

                    jsonWriter.WritePropertyName("healthCheck");
                    jsonWriter.WriteValue(healthCheck);

                    jsonWriter.WritePropertyName("isHealthy");
                    jsonWriter.WriteValue(healthCheckStatus.IsHealthy);

                    jsonWriter.WritePropertyName("failureReason");
                    jsonWriter.WriteValue(healthCheckStatus.FailureReason);

                    jsonWriter.WritePropertyName("dateTime");
                    jsonWriter.WriteValue(healthCheckStatus.DateTime);

                    jsonWriter.WriteEndObject();
                    jsonWriter.Flush();

                    content = new ByteArrayContent(mS.ToArray());
                    content.Headers.ContentType = new MediaTypeHeaderValue("application/json");
                }
            }

            return(CallAsync(content));
        }
Esempio n. 7
0
        public HealthMonitor(IDnsServer dnsServer, IPAddress address, HealthCheck healthCheck)
        {
            _dnsServer   = dnsServer;
            _address     = address;
            _healthCheck = healthCheck;

            _healthCheckTimer = new Timer(async delegate(object state)
            {
                try
                {
                    if (_healthCheck is null)
                    {
                        _healthCheckStatus = null;
                    }
                    else
                    {
                        HealthCheckStatus healthCheckStatus = await _healthCheck.IsHealthyAsync(_address);

                        bool sendAlert = false;

                        if (_healthCheckStatus is null)
                        {
                            if (!healthCheckStatus.IsHealthy)
                            {
                                sendAlert = true;
                            }
                        }
                        else
                        {
                            if (_healthCheckStatus.IsHealthy != healthCheckStatus.IsHealthy)
                            {
                                sendAlert = true;
                            }
                            else if (_healthCheckStatus.FailureReason != healthCheckStatus.FailureReason)
                            {
                                sendAlert = true;
                            }
                        }

                        if (sendAlert)
                        {
                            EmailAlert emailAlert = _healthCheck.EmailAlert;
                            if (emailAlert is not null)
                            {
                                _ = emailAlert.SendAlertAsync(_address, _healthCheck.Name, healthCheckStatus);
                            }

                            WebHook webHook = _healthCheck.WebHook;
                            if (webHook is not null)
                            {
                                _ = webHook.CallAsync(_address, _healthCheck.Name, healthCheckStatus);
                            }
                        }

                        _healthCheckStatus = healthCheckStatus;
                    }
                }
                catch (Exception ex)
                {
                    _dnsServer.WriteLog(ex);

                    if (_healthCheckStatus is null)
                    {
                        EmailAlert emailAlert = _healthCheck.EmailAlert;
                        if (emailAlert is not null)
                        {
                            _ = emailAlert.SendAlertAsync(_address, _healthCheck.Name, ex);
                        }

                        WebHook webHook = _healthCheck.WebHook;
                        if (webHook is not null)
                        {
                            _ = webHook.CallAsync(_address, _healthCheck.Name, ex);
                        }

                        _healthCheckStatus = new HealthCheckStatus(false, ex.ToString());
                    }
                    else
                    {
                        _healthCheckStatus = null;
                    }
                }
                finally
                {
                    if (!_disposed && (_healthCheck is not null))
                    {
                        _healthCheckTimer.Change(_healthCheck.Interval, Timeout.Infinite);
                    }
                }
            }, null, Timeout.Infinite, Timeout.Infinite);

            _healthCheckTimer.Change(0, Timeout.Infinite);
        }