Merge branch 'log-exporter' into develop

Apps/LogExporterApp/App.cs

@@ -0,0 +1,214 @@
+/*
+Technitium DNS Server
+Copyright (C) 2025  Shreyas Zare (shreyas@technitium.com)
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+*/
+
+using DnsServerCore.ApplicationCommon;
+using LogExporter.Strategy;
+using System;
+using System.Collections.Concurrent;
+using System.Collections.Generic;
+using System.Net;
+using System.Threading;
+using System.Threading.Tasks;
+using TechnitiumLibrary;
+using TechnitiumLibrary.Net.Dns;
+
+namespace LogExporter
+{
+    public sealed class App : IDnsApplication, IDnsQueryLogger
+    {
+        #region variables
+
+        IDnsServer? _dnsServer;
+        BufferManagementConfig? _config;
+
+        readonly ExportManager _exportManager = new ExportManager();
+
+        bool _enableLogging;
+
+        readonly ConcurrentQueue<LogEntry> _queuedLogs = new ConcurrentQueue<LogEntry>();
+        readonly Timer _queueTimer;
+        const int QUEUE_TIMER_INTERVAL = 10000;
+        const int BULK_INSERT_COUNT = 1000;
+
+        bool _disposed;
+
+        #endregion
+
+        #region constructor
+
+        public App()
+        {
+            _queueTimer = new Timer(HandleExportLogCallback);
+        }
+
+        #endregion
+
+        #region IDisposable
+
+        public void Dispose()
+        {
+            Dispose(disposing: true);
+            GC.SuppressFinalize(this);
+        }
+
+        private void Dispose(bool disposing)
+        {
+            if (!_disposed)
+            {
+                if (disposing)
+                {
+                    _queueTimer?.Dispose();
+
+                    ExportLogsAsync().Sync(); //flush any pending logs
+
+                    _exportManager.Dispose();
+                }
+
+                _disposed = true;
+            }
+        }
+
+        #endregion
+
+        #region public
+
+        public Task InitializeAsync(IDnsServer dnsServer, string config)
+        {
+            _dnsServer = dnsServer;
+            _config = BufferManagementConfig.Deserialize(config);
+
+            if (_config is null)
+                throw new DnsClientException("Invalid application configuration.");
+
+            if (_config.FileTarget!.Enabled)
+            {
+                _exportManager.RemoveStrategy(typeof(FileExportStrategy));
+                _exportManager.AddStrategy(new FileExportStrategy(_config.FileTarget!.Path));
+            }
+            else
+            {
+                _exportManager.RemoveStrategy(typeof(FileExportStrategy));
+            }
+
+            if (_config.HttpTarget!.Enabled)
+            {
+                _exportManager.RemoveStrategy(typeof(HttpExportStrategy));
+                _exportManager.AddStrategy(new HttpExportStrategy(_config.HttpTarget.Endpoint, _config.HttpTarget.Headers));
+            }
+            else
+            {
+                _exportManager.RemoveStrategy(typeof(HttpExportStrategy));
+            }
+
+            if (_config.SyslogTarget!.Enabled)
+            {
+                _exportManager.RemoveStrategy(typeof(SyslogExportStrategy));
+                _exportManager.AddStrategy(new SyslogExportStrategy(_config.SyslogTarget.Address, _config.SyslogTarget.Port, _config.SyslogTarget.Protocol));
+            }
+            else
+            {
+                _exportManager.RemoveStrategy(typeof(SyslogExportStrategy));
+            }
+
+            _enableLogging = _exportManager.HasStrategy();
+
+            if (_enableLogging)
+                _queueTimer.Change(QUEUE_TIMER_INTERVAL, Timeout.Infinite);
+            else
+                _queueTimer.Change(Timeout.Infinite, Timeout.Infinite);
+
+            return Task.CompletedTask;
+        }
+
+        public Task InsertLogAsync(DateTime timestamp, DnsDatagram request, IPEndPoint remoteEP, DnsTransportProtocol protocol, DnsDatagram response)
+        {
+            if (_enableLogging)
+            {
+                if (_queuedLogs.Count < _config!.MaxQueueSize)
+                    _queuedLogs.Enqueue(new LogEntry(timestamp, remoteEP, protocol, request, response));
+            }
+
+            return Task.CompletedTask;
+        }
+
+        #endregion
+
+        #region private
+
+        private async Task ExportLogsAsync()
+        {
+            try
+            {
+                List<LogEntry> logs = new List<LogEntry>(BULK_INSERT_COUNT);
+
+                while (true)
+                {
+                    while (logs.Count < BULK_INSERT_COUNT && _queuedLogs.TryDequeue(out LogEntry? log))
+                    {
+                        logs.Add(log);
+                    }
+
+                    if (logs.Count < 1)
+                        break;
+
+                    await _exportManager.ImplementStrategyAsync(logs);
+
+                    logs.Clear();
+                }
+            }
+            catch (Exception ex)
+            {
+                _dnsServer?.WriteLog(ex);
+            }
+        }
+
+        private async void HandleExportLogCallback(object? state)
+        {
+            try
+            {
+                // Process logs within the timer interval, then let the timer reschedule
+                await ExportLogsAsync();
+            }
+            catch (Exception ex)
+            {
+                _dnsServer?.WriteLog(ex);
+            }
+            finally
+            {
+                try
+                {
+                    _queueTimer?.Change(QUEUE_TIMER_INTERVAL, Timeout.Infinite);
+                }
+                catch (ObjectDisposedException)
+                { }
+            }
+        }
+
+        #endregion
+
+        #region properties
+
+        public string Description
+        {
+            get { return "Allows exporting query logs to third party sinks. It supports exporting to File, HTTP endpoint, and Syslog (UDP, TCP, TLS, and Local protocols)."; }
+        }
+
+        #endregion
+    }
+}

Apps/LogExporterApp/BufferManagementConfig.cs

@@ -0,0 +1,94 @@
+/*
+Technitium DNS Server
+Copyright (C) 2025  Shreyas Zare (shreyas@technitium.com)
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+*/
+
+using System.Collections.Generic;
+using System.Text.Json;
+using System.Text.Json.Serialization;
+
+namespace LogExporter
+{
+    public class BufferManagementConfig
+    {
+        [JsonPropertyName("maxQueueSize")]
+        public int MaxQueueSize
+        { get; set; }
+
+        [JsonPropertyName("file")]
+        public FileTarget? FileTarget { get; set; }
+
+        [JsonPropertyName("http")]
+        public HttpTarget? HttpTarget { get; set; }
+
+        [JsonPropertyName("syslog")]
+        public SyslogTarget? SyslogTarget { get; set; }
+
+        // Load configuration from JSON
+        public static BufferManagementConfig? Deserialize(string json)
+        {
+            return JsonSerializer.Deserialize<BufferManagementConfig>(json, DnsConfigSerializerOptions.Default);
+        }
+    }
+
+    public class TargetBase
+    {
+        [JsonPropertyName("enabled")]
+        public bool Enabled { get; set; }
+    }
+
+    public class SyslogTarget : TargetBase
+    {
+        [JsonPropertyName("address")]
+        public string Address { get; set; }
+
+        [JsonPropertyName("port")]
+        public int? Port { get; set; }
+
+        [JsonPropertyName("protocol")]
+        public string? Protocol { get; set; }
+    }
+
+    public class FileTarget : TargetBase
+    {
+        [JsonPropertyName("path")]
+        public string Path { get; set; }
+    }
+
+    public class HttpTarget : TargetBase
+    {
+        [JsonPropertyName("endpoint")]
+        public string Endpoint { get; set; }
+
+        [JsonPropertyName("headers")]
+        public Dictionary<string, string?>? Headers { get; set; }
+    }
+
+    // Setup reusable options with a single instance
+    public static class DnsConfigSerializerOptions
+    {
+        public static readonly JsonSerializerOptions Default = new JsonSerializerOptions
+        {
+            PropertyNamingPolicy = JsonNamingPolicy.CamelCase, // Convert properties to camelCase
+            Encoder = System.Text.Encodings.Web.JavaScriptEncoder.UnsafeRelaxedJsonEscaping, // For safe encoding
+            NumberHandling = JsonNumberHandling.Strict,
+            AllowTrailingCommas = true, // Allow trailing commas in JSON
+            DictionaryKeyPolicy = JsonNamingPolicy.CamelCase, // Convert dictionary keys to camelCase
+            DefaultIgnoreCondition = JsonIgnoreCondition.WhenWritingNull // Ignore null values
+        };
+    }
+}

Apps/LogExporterApp/LogEntry.cs

@@ -0,0 +1,138 @@
+/*
+Technitium DNS Server
+Copyright (C) 2025  Shreyas Zare (shreyas@technitium.com)
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+*/
+
+using DnsServerCore.ApplicationCommon;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Net;
+using System.Text.Json;
+using System.Text.Json.Serialization;
+using TechnitiumLibrary.Net.Dns;
+using TechnitiumLibrary.Net.Dns.ResourceRecords;
+
+namespace LogExporter
+{
+    public class LogEntry
+    {
+        public DateTime Timestamp { get; private set; }
+        public string ClientIp { get; private set; }
+        public DnsTransportProtocol Protocol { get; private set; }
+        public DnsServerResponseType ResponseType { get; private set; }
+        public double? ResponseRtt { get; private set; }
+        public DnsResponseCode ResponseCode { get; private set; }
+        public DnsQuestion? Question { get; private set; }
+        public List<DnsResourceRecord> Answers { get; private set; }
+
+        public LogEntry(DateTime timestamp, IPEndPoint remoteEP, DnsTransportProtocol protocol, DnsDatagram request, DnsDatagram response)
+        {
+            // Assign timestamp and ensure it's in UTC
+            Timestamp = timestamp.Kind == DateTimeKind.Utc ? timestamp : timestamp.ToUniversalTime();
+
+            // Extract client information
+            ClientIp = remoteEP.Address.ToString();
+            Protocol = protocol;
+            ResponseType = response.Tag == null ? DnsServerResponseType.Recursive : (DnsServerResponseType)response.Tag;
+
+            if ((ResponseType == DnsServerResponseType.Recursive) && (response.Metadata is not null))
+                ResponseRtt = response.Metadata.RoundTripTime;
+
+            ResponseCode = response.RCODE;
+
+            // Extract request information
+            if (request.Question.Count > 0)
+            {
+                DnsQuestionRecord query = request.Question[0];
+
+                Question = new DnsQuestion
+                {
+                    QuestionName = query.Name,
+                    QuestionType = query.Type,
+                    QuestionClass = query.Class,
+                };
+            }
+
+            // Convert answer section into a simple string summary (comma-separated for multiple answers)
+            Answers = new List<DnsResourceRecord>(response.Answer.Count);
+            if (response.Answer.Count > 0)
+            {
+                Answers.AddRange(response.Answer.Select(record => new DnsResourceRecord
+                {
+                    Name = record.Name,
+                    RecordType = record.Type,
+                    RecordClass = record.Class,
+                    RecordTtl = record.TTL,
+                    RecordData = record.RDATA.ToString(),
+                    DnssecStatus = record.DnssecStatus,
+                }));
+            }
+        }
+
+        public class DnsQuestion
+        {
+            public string QuestionName { get; set; }
+            public DnsResourceRecordType QuestionType { get; set; }
+            public DnsClass QuestionClass { get; set; }
+        }
+
+        public class DnsResourceRecord
+        {
+            public string Name { get; set; }
+            public DnsResourceRecordType RecordType { get; set; }
+            public DnsClass RecordClass { get; set; }
+            public uint RecordTtl { get; set; }
+            public string RecordData { get; set; }
+            public DnssecStatus DnssecStatus { get; set; }
+        }
+
+        public override string ToString()
+        {
+            return JsonSerializer.Serialize(this, DnsLogSerializerOptions.Default);
+        }
+
+        // Custom DateTime converter to handle UTC serialization in ISO 8601 format
+        public class JsonDateTimeConverter : JsonConverter<DateTime>
+        {
+            public override DateTime Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
+            {
+                string? dts = reader.GetString();
+                return dts == null ? DateTime.MinValue : DateTime.Parse(dts);
+            }
+
+            public override void Write(Utf8JsonWriter writer, DateTime value, JsonSerializerOptions options)
+            {
+                writer.WriteStringValue(value.ToUniversalTime().ToString("yyyy-MM-ddTHH:mm:ss.fffZ"));
+            }
+        }
+
+        // Setup reusable options with a single instance
+        public static class DnsLogSerializerOptions
+        {
+            public static readonly JsonSerializerOptions Default = new JsonSerializerOptions
+            {
+                WriteIndented = false, // Newline delimited logs should not be multiline
+                PropertyNamingPolicy = JsonNamingPolicy.CamelCase, // Convert properties to camelCase
+                Converters = { new JsonStringEnumConverter(), new JsonDateTimeConverter() }, // Handle enums and DateTime conversion
+                Encoder = System.Text.Encodings.Web.JavaScriptEncoder.UnsafeRelaxedJsonEscaping, // For safe encoding
+                NumberHandling = JsonNumberHandling.Strict,
+                DefaultIgnoreCondition = JsonIgnoreCondition.WhenWritingNull // Ignore null values
+            };
+        }
+    }
+}

Apps/LogExporterApp/LogExporterApp.csproj

@@ -0,0 +1,53 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>net8.0</TargetFramework>
+    <AppendTargetFrameworkToOutputPath>false</AppendTargetFrameworkToOutputPath>
+    <CopyLocalLockFileAssemblies>true</CopyLocalLockFileAssemblies>
+    <Version>1.0</Version>
+    <IncludeSourceRevisionInInformationalVersion>false</IncludeSourceRevisionInInformationalVersion>
+    <Company>Technitium</Company>
+    <Product>Technitium DNS Server</Product>
+    <Authors>Zafer Balkan</Authors>
+    <AssemblyName>LogExporterApp</AssemblyName>
+    <RootNamespace>LogExporter</RootNamespace>
+    <PackageProjectUrl>https://technitium.com/dns/</PackageProjectUrl>
+    <RepositoryUrl>https://github.com/TechnitiumSoftware/DnsServer</RepositoryUrl>
+    <Description>Allows exporting query logs to third party sinks. It supports exporting to File, HTTP endpoint, and Syslog (UDP, TCP, TLS, and Local protocols).</Description>
+    <GeneratePackageOnBuild>false</GeneratePackageOnBuild>
+    <OutputType>Library</OutputType>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Microsoft.Extensions.Configuration" Version="9.0.0" />
+    <PackageReference Include="Serilog.Sinks.File" Version="6.0.0" />
+    <PackageReference Include="Serilog.Sinks.Http" Version="9.0.0" />
+    <PackageReference Include="Serilog.Sinks.PeriodicBatching" Version="5.0.0" />
+    <PackageReference Include="Serilog.Sinks.SyslogMessages" Version="4.0.0" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\..\DnsServerCore.ApplicationCommon\DnsServerCore.ApplicationCommon.csproj">
+      <Private>false</Private>
+    </ProjectReference>
+  </ItemGroup>
+
+  <ItemGroup>
+    <Reference Include="TechnitiumLibrary.Net">
+      <HintPath>..\..\..\TechnitiumLibrary\bin\TechnitiumLibrary.Net.dll</HintPath>
+      <Private>false</Private>
+    </Reference>
+    <Reference Include="TechnitiumLibrary">
+      <HintPath>..\..\..\TechnitiumLibrary\bin\TechnitiumLibrary.dll</HintPath>
+      <Private>false</Private>
+    </Reference>
+  </ItemGroup>
+
+  <ItemGroup>
+    <None Update="dnsApp.config">
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+    </None>
+  </ItemGroup>
+
+</Project>

Apps/LogExporterApp/Strategy/ExportManager.cs

@@ -0,0 +1,82 @@
+/*
+Technitium DNS Server
+Copyright (C) 2025  Shreyas Zare (shreyas@technitium.com)
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+*/
+
+using System;
+using System.Collections.Concurrent;
+using System.Collections.Generic;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace LogExporter.Strategy
+{
+    public sealed class ExportManager : IDisposable
+    {
+        #region variables
+
+        readonly ConcurrentDictionary<Type, IExportStrategy> _exportStrategies = new ConcurrentDictionary<Type, IExportStrategy>();
+
+        #endregion
+
+        #region IDisposable
+
+        public void Dispose()
+        {
+            foreach (KeyValuePair<Type, IExportStrategy> exportStrategy in _exportStrategies)
+                exportStrategy.Value.Dispose();
+        }
+
+        #endregion
+
+        #region public
+
+        public void AddStrategy(IExportStrategy strategy)
+        {
+            if (!_exportStrategies.TryAdd(strategy.GetType(), strategy))
+                throw new InvalidOperationException();
+        }
+
+        public void RemoveStrategy(Type type)
+        {
+            if (_exportStrategies.TryRemove(type, out IExportStrategy? existing))
+                existing?.Dispose();
+        }
+
+        public bool HasStrategy()
+        {
+            return !_exportStrategies.IsEmpty;
+        }
+
+        public async Task ImplementStrategyAsync(IReadOnlyList<LogEntry> logs)
+        {
+            List<Task> tasks = new List<Task>(_exportStrategies.Count);
+
+            foreach (KeyValuePair<Type, IExportStrategy> strategy in _exportStrategies)
+            {
+                tasks.Add(Task.Factory.StartNew(delegate (object? state)
+                {
+                    return strategy.Value.ExportAsync(logs);
+                }, null, CancellationToken.None, TaskCreationOptions.DenyChildAttach, TaskScheduler.Current));
+            }
+
+            await Task.WhenAll(tasks);
+        }
+
+        #endregion
+    }
+}

Apps/LogExporterApp/Strategy/FileExportStrategy.cs

@@ -0,0 +1,71 @@
+/*
+Technitium DNS Server
+Copyright (C) 2025  Shreyas Zare (shreyas@technitium.com)
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+*/
+
+using Serilog;
+using System.Collections.Generic;
+using System.Threading.Tasks;
+
+namespace LogExporter.Strategy
+{
+    public sealed class FileExportStrategy : IExportStrategy
+    {
+        #region variables
+
+        readonly Serilog.Core.Logger _sender;
+
+        bool _disposed;
+
+        #endregion
+
+        #region constructor
+
+        public FileExportStrategy(string filePath)
+        {
+            _sender = new LoggerConfiguration().WriteTo.File(filePath, outputTemplate: "{Message:lj}{NewLine}{Exception}").CreateLogger();
+        }
+
+        #endregion
+
+        #region IDisposable
+
+        public void Dispose()
+        {
+            if (!_disposed)
+            {
+                _sender.Dispose();
+
+                _disposed = true;
+            }
+        }
+
+        #endregion
+
+        #region public
+
+        public Task ExportAsync(IReadOnlyList<LogEntry> logs)
+        {
+            foreach (LogEntry logEntry in logs)
+                _sender.Information(logEntry.ToString());
+
+            return Task.CompletedTask;
+        }
+
+        #endregion
+    }
+}

Apps/LogExporterApp/Strategy/HttpExportStrategy.cs

@@ -0,0 +1,119 @@
+/*
+Technitium DNS Server
+Copyright (C) 2025  Shreyas Zare (shreyas@technitium.com)
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+*/
+
+using Microsoft.Extensions.Configuration;
+using Serilog;
+using Serilog.Sinks.Http;
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Net.Http;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace LogExporter.Strategy
+{
+    public sealed class HttpExportStrategy : IExportStrategy
+    {
+        #region variables
+
+        readonly Serilog.Core.Logger _sender;
+
+        bool _disposed;
+
+        #endregion
+
+        #region constructor
+
+        public HttpExportStrategy(string endpoint, Dictionary<string, string?>? headers = null)
+        {
+            IConfigurationRoot? configuration = null;
+            if (headers != null)
+            {
+                configuration = new ConfigurationBuilder()
+               .AddInMemoryCollection(headers)
+               .Build();
+            }
+
+            _sender = new LoggerConfiguration().WriteTo.Http(endpoint, null, httpClient: new CustomHttpClient(), configuration: configuration).Enrich.FromLogContext().CreateLogger();
+        }
+
+        #endregion
+
+        #region IDisposable
+
+        public void Dispose()
+        {
+            if (!_disposed)
+            {
+                _sender.Dispose();
+
+                _disposed = true;
+            }
+        }
+
+        #endregion
+
+        #region public
+
+        public Task ExportAsync(IReadOnlyList<LogEntry> logs)
+        {
+            foreach (LogEntry logEntry in logs)
+                _sender.Information(logEntry.ToString());
+
+            return Task.CompletedTask;
+        }
+
+        #endregion
+
+        public class CustomHttpClient : IHttpClient
+        {
+            readonly HttpClient _httpClient;
+
+            public CustomHttpClient()
+            {
+                _httpClient = new HttpClient();
+            }
+
+            public void Configure(IConfiguration configuration)
+            {
+                foreach (IConfigurationSection pair in configuration.GetChildren())
+                {
+                    _httpClient.DefaultRequestHeaders.Add(pair.Key, pair.Value);
+                }
+            }
+
+            public void Dispose()
+            {
+                _httpClient?.Dispose();
+                GC.SuppressFinalize(this);
+            }
+
+            public async Task<HttpResponseMessage> PostAsync(string requestUri, Stream contentStream, CancellationToken cancellationToken)
+            {
+                StreamContent content = new StreamContent(contentStream);
+                content.Headers.Add("Content-Type", "application/json");
+
+                return await _httpClient
+                    .PostAsync(requestUri, content, cancellationToken)
+                    .ConfigureAwait(false);
+            }
+        }
+    }
+}

Apps/LogExporterApp/Strategy/IExportStrategy.cs

@@ -0,0 +1,33 @@
+/*
+Technitium DNS Server
+Copyright (C) 2025  Shreyas Zare (shreyas@technitium.com)
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+*/
+
+using System;
+using System.Collections.Generic;
+using System.Threading.Tasks;
+
+namespace LogExporter.Strategy
+{
+    /// <summary>
+    ///     Strategy interface to decide the sinks for exporting the logs.
+    /// </summary>
+    public interface IExportStrategy: IDisposable
+    {
+        Task ExportAsync(IReadOnlyList<LogEntry> logs);
+    }
+}

Apps/LogExporterApp/Strategy/SyslogExportStrategy.cs

@@ -0,0 +1,171 @@
+/*
+Technitium DNS Server
+Copyright (C) 2025  Shreyas Zare (shreyas@technitium.com)
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+*/
+
+using Serilog;
+using Serilog.Events;
+using Serilog.Parsing;
+using Serilog.Sinks.Syslog;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading.Tasks;
+
+namespace LogExporter.Strategy
+{
+    public sealed class SyslogExportStrategy : IExportStrategy
+    {
+        #region variables
+
+        const string _appName = "Technitium DNS Server";
+        const string _sdId = "meta";
+        const string DEFAUL_PROTOCOL = "udp";
+        const int DEFAULT_PORT = 514;
+
+        readonly Facility _facility = Facility.Local6;
+
+        readonly Rfc5424Formatter _formatter;
+        readonly Serilog.Core.Logger _sender;
+
+        bool _disposed;
+
+        #endregion
+
+        #region constructor
+
+        public SyslogExportStrategy(string address, int? port, string? protocol)
+        {
+            port ??= DEFAULT_PORT;
+            protocol ??= DEFAUL_PROTOCOL;
+
+            LoggerConfiguration conf = new LoggerConfiguration();
+
+            _sender = protocol.ToLowerInvariant() switch
+            {
+                "tls" => conf.WriteTo.TcpSyslog(address, port.Value, _appName, FramingType.OCTET_COUNTING, SyslogFormat.RFC5424, _facility, useTls: true).Enrich.FromLogContext().CreateLogger(),
+                "tcp" => conf.WriteTo.TcpSyslog(address, port.Value, _appName, FramingType.OCTET_COUNTING, SyslogFormat.RFC5424, _facility, useTls: false).Enrich.FromLogContext().CreateLogger(),
+                "udp" => conf.WriteTo.UdpSyslog(address, port.Value, _appName, SyslogFormat.RFC5424, _facility).Enrich.FromLogContext().CreateLogger(),
+                "local" => conf.WriteTo.LocalSyslog(_appName, _facility).Enrich.FromLogContext().CreateLogger(),
+                _ => throw new NotSupportedException("Syslog protocol is not supported: " + protocol),
+            };
+
+            _formatter = new Rfc5424Formatter(_facility, _appName, null, _sdId, Environment.MachineName);
+        }
+
+        #endregion
+
+        #region IDisposable
+
+        public void Dispose()
+        {
+            if (!_disposed)
+            {
+                _sender.Dispose();
+
+                _disposed = true;
+            }
+        }
+
+        #endregion
+
+        #region public
+
+        public Task ExportAsync(IReadOnlyList<LogEntry> logs)
+        {
+            foreach (LogEntry log in logs)
+                _sender.Information(_formatter.FormatMessage((LogEvent?)Convert(log)));
+
+            return Task.CompletedTask;
+        }
+
+        #endregion
+
+        #region private
+
+        private static LogEvent Convert(LogEntry log)
+        {
+            // Initialize properties with base log details
+            List<LogEventProperty> properties = new List<LogEventProperty>
+            {
+                new LogEventProperty("timestamp", new ScalarValue(log.Timestamp.ToString("yyyy-MM-ddTHH:mm:ss.fffZ"))),
+                new LogEventProperty("clientIp", new ScalarValue(log.ClientIp)),
+                new LogEventProperty("protocol", new ScalarValue(log.Protocol.ToString())),
+                new LogEventProperty("responseType", new ScalarValue(log.ResponseType.ToString())),
+                new LogEventProperty("responseRtt", new ScalarValue(log.ResponseRtt?.ToString())),
+                new LogEventProperty("rCode", new ScalarValue(log.ResponseCode.ToString()))
+            };
+
+            // Add each question as properties
+            if (log.Question != null)
+            {
+                LogEntry.DnsQuestion question = log.Question;
+                properties.Add(new LogEventProperty("qName", new ScalarValue(question.QuestionName)));
+                properties.Add(new LogEventProperty("qType", new ScalarValue(question.QuestionType.ToString())));
+                properties.Add(new LogEventProperty("qClass", new ScalarValue(question.QuestionClass.ToString())));
+
+                string questionSummary = $"QNAME: {question.QuestionName}, QTYPE: {question.QuestionType.ToString()}, QCLASS: {question.QuestionClass.ToString()}";
+                properties.Add(new LogEventProperty("questionsSummary", new ScalarValue(questionSummary)));
+            }
+            else
+            {
+                properties.Add(new LogEventProperty("questionsSummary", new ScalarValue(string.Empty)));
+            }
+
+            // Add each answer as properties
+            if (log.Answers.Count > 0)
+            {
+                for (int i = 0; i < log.Answers.Count; i++)
+                {
+                    LogEntry.DnsResourceRecord answer = log.Answers[i];
+
+                    properties.Add(new LogEventProperty($"aName_{i}", new ScalarValue(answer.Name)));
+                    properties.Add(new LogEventProperty($"aType_{i}", new ScalarValue(answer.RecordType.ToString())));
+                    properties.Add(new LogEventProperty($"aClass_{i}", new ScalarValue(answer.RecordClass.ToString())));
+                    properties.Add(new LogEventProperty($"aTtl_{i}", new ScalarValue(answer.RecordTtl.ToString())));
+                    properties.Add(new LogEventProperty($"aRData_{i}", new ScalarValue(answer.RecordData)));
+                    properties.Add(new LogEventProperty($"aDnssecStatus_{i}", new ScalarValue(answer.DnssecStatus.ToString())));
+                }
+
+                // Generate answers summary
+                string answerSummary = string.Join(", ", log.Answers.Select(a => a.RecordData));
+                properties.Add(new LogEventProperty("answersSummary", new ScalarValue(answerSummary)));
+            }
+            else
+            {
+                properties.Add(new LogEventProperty("answersSummary", new ScalarValue(string.Empty)));
+            }
+
+            // Define the message template to match the original summary format
+            const string templateText = "{questionsSummary}; RCODE: {rCode}; ANSWER: [{answersSummary}]";
+
+            // Parse the template
+            MessageTemplate template = new MessageTemplateParser().Parse(templateText);
+
+            // Create the LogEvent and return it
+            return new LogEvent(
+                timestamp: log.Timestamp,
+                level: LogEventLevel.Information,
+                exception: null,
+                messageTemplate: template,
+                properties: properties
+            );
+        }
+
+        #endregion
+    }
+}

Apps/LogExporterApp/dnsApp.config

@@ -0,0 +1,20 @@
+{
+  "maxQueueSize": 1000000,
+  "file": {
+    "path": "./dns_logs.json",
+    "enabled": false
+  },
+  "http": {
+    "endpoint": "http://localhost:5000/logs",
+    "headers": {
+      "Authorization": "Bearer abc123"
+    },
+    "enabled": false
+  },
+  "syslog": {
+    "address": "127.0.0.1",
+    "port": 514,
+    "protocol": "UDP",
+    "enabled": false
+  }
+}

DnsServer.sln

@@ -31,6 +31,8 @@ Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "DropRequestsApp", "Apps\Dro
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "QueryLogsSqliteApp", "Apps\QueryLogsSqliteApp\QueryLogsSqliteApp.csproj", "{186DEF23-863E-4954-BE16-5E5FCA75ECA2}"
 EndProject
+Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "LogExporterApp", "Apps\LogExporterApp\LogExporterApp.csproj", "{6F9BCCA9-6422-484B-A065-EF8AF9DA74B5}"
+EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "AdvancedBlockingApp", "Apps\AdvancedBlockingApp\AdvancedBlockingApp.csproj", "{A4C31093-CA65-42D4-928A-11907076C0DE}"
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "NxDomainApp", "Apps\NxDomainApp\NxDomainApp.csproj", "{BB0010FC-20E9-4397-BF9B-C9955D9AD339}"
@@ -61,6 +63,11 @@ Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "DnsRebindingProtectionApp",
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "FilterAaaaApp", "Apps\FilterAaaaApp\FilterAaaaApp.csproj", "{0A9B7F39-80DA-4084-AD47-8707576927ED}"
 EndProject
+Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Solution Items", "Solution Items", "{3746EF13-91C5-4858-9DC2-D3C2504BD135}"
+	ProjectSection(SolutionItems) = preProject
+		.editorconfig = .editorconfig
+	EndProjectSection
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -119,6 +126,10 @@ Global
 		{186DEF23-863E-4954-BE16-5E5FCA75ECA2}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{186DEF23-863E-4954-BE16-5E5FCA75ECA2}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{186DEF23-863E-4954-BE16-5E5FCA75ECA2}.Release|Any CPU.Build.0 = Release|Any CPU
+		{6F9BCCA9-6422-484B-A065-EF8AF9DA74B5}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{6F9BCCA9-6422-484B-A065-EF8AF9DA74B5}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{6F9BCCA9-6422-484B-A065-EF8AF9DA74B5}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{6F9BCCA9-6422-484B-A065-EF8AF9DA74B5}.Release|Any CPU.Build.0 = Release|Any CPU
 		{A4C31093-CA65-42D4-928A-11907076C0DE}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
 		{A4C31093-CA65-42D4-928A-11907076C0DE}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{A4C31093-CA65-42D4-928A-11907076C0DE}.Release|Any CPU.ActiveCfg = Release|Any CPU
@@ -192,6 +203,7 @@ Global
 		{099D27AF-3AEB-495A-A5D0-46DA59CC9213} = {938BF8EF-74B9-4FE0-B46F-11EBB7A4B3D2}
 		{738079D1-FA5A-40CD-8A27-D831919EE209} = {938BF8EF-74B9-4FE0-B46F-11EBB7A4B3D2}
 		{186DEF23-863E-4954-BE16-5E5FCA75ECA2} = {938BF8EF-74B9-4FE0-B46F-11EBB7A4B3D2}
+		{6F9BCCA9-6422-484B-A065-EF8AF9DA74B5} = {938BF8EF-74B9-4FE0-B46F-11EBB7A4B3D2}
 		{A4C31093-CA65-42D4-928A-11907076C0DE} = {938BF8EF-74B9-4FE0-B46F-11EBB7A4B3D2}
 		{BB0010FC-20E9-4397-BF9B-C9955D9AD339} = {938BF8EF-74B9-4FE0-B46F-11EBB7A4B3D2}
 		{45C6F9AD-57D6-4D6D-9498-10B5C828E47E} = {938BF8EF-74B9-4FE0-B46F-11EBB7A4B3D2}