Review

README.md

@@ -0,0 +1,82 @@
+# pdns-dhcp
+
+Enabling PowerDNS to query popular supported Dhcp-servers.
+
+This project was born out of the necessity for my home-lab network to be able to resolve both IPv4 and IPv6 addresses from one Dhcp-service.
+
+Theoretically Kea can update DNS servers using RFC2136 nsupdate-mechanisms using kea-ddns, but this interoperation can cause issues in networks with devices sharing a hostname (i.e. DHCID records), missing update requests due to service restarts or temporary connectivity issues.
+
+## Scope
+
+At the moment there is no need to implement more than is minimally required to get Dhcp4 and Dhcp6 leases queryable by PowerDNS using the memfile "database" of Kea using the remote backend with unix domain sockets.
+
+Following parts may be implemented later as I see fit:
+- Different PowerDNS remote backends
+  - mainly HTTP REST
+- Support different Kea lease databases
+  - MySQL
+  - PostgreSQL
+
+## Building
+
+Requires .NET 8 SDK  
+Create binary using
+> dotnet publish -c Release -p:PublishTrimmed=true -p:PublishSingleFile=true --self-contained
+
+## Usage
+
+Install, and configure Kea (optionally with Stork) Dhcp4, Dhcp6 or both.  
+Make sure to enable the memfile lease store.
+
+Install and configure PowerDNS, including the [remote backend](https://doc.powerdns.com/authoritative/backends/remote.html).  
+A sample configuration file is provided.
+
+Deploy pdns-dhcp to /opt/pdns-dhcp  
+Setup systemd using the provided socket and service units, configure as necessary.
+
+Start Kea, pdns-dhcp and PowerDNS.
+
+**To be done**: Packaging for common Linux distributions.  
+Deb-packages (Debian)  
+RPM-packages (EL)
+
+### Configuration
+
+pdns-dhcp can be configured using environment variables or the appsettings.json file - [Configuration#Binding hierarchies](https://learn.microsoft.com/dotnet/core/extensions/configuration#binding-hierarchies) describes the naming scheme in this section.
+
+Default configuration:
+```
+Dhcp:Kea:Dhcp4:Leases=/var/lib/kea/kea-leases4.csv
+Dhcp:Kea:Dhcp6:Leases=/var/lib/kea/kea-leases6.csv
+PowerDns:UniqueHostnames=true
+PowerDns:Listener:Socket=/run/pdns-dhcp/pdns.sock
+```
+
+`Dhcp:Kea` allows configuring `Dhcp4` and `Dhcp6` lease file watchers, respective for each of both services.
+
+In `PowerDns:Listener:Socket` you can optionally configure the unix domain socket to be used in case Systemd isn't providing them (e.g. when starting the service manually).
+
+pdns-dhcp continuously monitors the Dhcp service leases and upon seeing a new lease all previous records that match in hostname and lease type (IPv4, IPv6) are replaced. If you want to change this behavior you can opt-out of this behavior by setting `PowerDns:UniqueHostnames=false`.
+
+See [Logging in C#](https://learn.microsoft.com/dotnet/core/extensions/logging?tabs=command-line#configure-logging-without-code) for options related to logging.
+
+## Acknowledgments
+
+Incorporates following libraries directly:
+
+**.NET Foundation and Contributors**
+- [CommunityToolkit.HighPerformance](https://github.com/CommunityToolkit/dotnet) - MIT
+- [dotNext](https://github.com/dotnet/dotNext) - MIT
+- Several runtime libraries, as part of [.NET](https://github.com/dotnet/runtime)
+  - Microsoft.AspNetCore.App
+  - Microsoft.Extensions.Configuration.Binder
+  - Microsoft.Extensions.Hosting.Systemd
+  - System.IO.Pipelines
+
+**[Nietras](https://github.com/nietras)**
+- [Sep](https://github.com/nietras/Sep) - MIT
+
+Incorporates data structures and protocol implementations as required for interop scenarios:
+
+- [kea](https://gitlab.isc.org/isc-projects/kea) by [ISC](https://isc.org/) - MPL 2.0
+- [PowerDNS](https://github.com/PowerDNS/pdns) by [PowerDNS.COM BV](https://www.powerdns.com/) and contributors - GPL 2.0

ext/powerdns/pdns-dhcp.conf

@@ -0,0 +1,2 @@
+launch+=remote
+remote-connection-string+=unix:path=/run/pdns-dhcp/pdns.sock

ext/systemd/pdns-dhcp.socket

@@ -1,11 +1,8 @@
-# WARNING
-# This currently not supported.
-
 [Unit]
 Description=pdns-dhcp PowerDNS Remote Socket
 
 [Socket]
-ListenStream=/run/pdns-dhcp/pdns-dhcp.sock
+ListenStream=/run/pdns-dhcp/pdns.sock
 Accept=no
 
 [Install]

src/pdns-dhcp/Kea/KeaDhcpLease.cs

@@ -43,7 +43,7 @@ public static class KeaDhcpLease
 
 				if (converted)
 				{
-					writer.Write(escapedChar);
+					writer.Write([escapedChar]);
 				}
 				else
 				{

src/pdns-dhcp/Kea/KeaDhcpLeaseWatcher.cs

@@ -170,11 +170,15 @@ public sealed class KeaDhcpLeaseWatcher : IHostedService
 					{
 						if (reader is null)
 						{
+							// LongRunning, force spawning a thread
+							// As this may block for a long time.
 							reader = await Task.Factory.StartNew(
 								s => MemfileReader.From((Stream)s!),
 								_pipe.Reader.AsStream(),
 								stoppingToken,
-								TaskCreationOptions.AttachedToParent, TaskScheduler.Default);
+								TaskCreationOptions.DenyChildAttach | TaskCreationOptions.LongRunning,
+								TaskScheduler.Default)
+								.ConfigureAwait(false);
 							continue;
 						}
 
@@ -202,7 +206,7 @@ public sealed class KeaDhcpLeaseWatcher : IHostedService
 					}
 					else
 					{
-						await waitHandle.WaitOneAsync(stoppingToken).ConfigureAwait(continueOnCapturedContext: false);
+						await waitHandle.WaitOneAsync(stoppingToken).ConfigureAwait(false);
 					}
 				}
 			}

src/pdns-dhcp/Kea/KeaService.cs

@@ -49,6 +49,6 @@ public class KeaService : IHostedService
 		var waitTask = Task.WhenAll(tasks);
 		TaskCompletionSource taskCompletionSource = new();
 		using var registration = cancellationToken.Register(s => ((TaskCompletionSource)s!).SetCanceled(), taskCompletionSource);
-		await Task.WhenAny(waitTask, taskCompletionSource.Task).ConfigureAwait(continueOnCapturedContext: false);
+		await Task.WhenAny(waitTask, taskCompletionSource.Task).ConfigureAwait(false);
 	}
 }

src/pdns-dhcp/PowerDns/Methods.cs

@@ -1,21 +1,12 @@
-using System.Text.Json.Serialization;
-
 namespace pdns_dhcp.PowerDns;
 
 public interface IMethod;
 
-[JsonPolymorphic(TypeDiscriminatorPropertyName = "method")]
+public record MethodBase(string Method);
-[JsonDerivedType(typeof(InitializeMethod), "initialize")]
-[JsonDerivedType(typeof(LookupMethod), "lookup")]
-public class Method;
 
-public abstract class Method<TParam>(TParam parameters) : Method
+public record Method<TParam>(string Method, TParam Parameters) : MethodBase(Method)
-	where TParam : MethodParameters
+	where TParam : MethodParameters;
-{
-	[JsonPropertyName("parameters")]
-	public TParam Parameters => parameters;
-}
 
-public class InitializeMethod(InitializeParameters parameters) : Method<InitializeParameters>(parameters), IMethod;
+public record InitializeMethod(InitializeParameters Parameters) : Method<InitializeParameters>("initialize", Parameters), IMethod;
 
-public class LookupMethod(LookupParameters parameters) : Method<LookupParameters>(parameters), IMethod;
+public record LookupMethod(LookupParameters Parameters) : Method<LookupParameters>("lookup", Parameters), IMethod;

src/pdns-dhcp/PowerDns/Parameters.cs

@@ -1,16 +1,43 @@
+using System.Text;
 using System.Text.Json;
 using System.Text.Json.Serialization;
 
 namespace pdns_dhcp.PowerDns;
 
-[JsonDerivedType(typeof(InitializeParameters))]
-[JsonDerivedType(typeof(LookupParameters))]
 public record class Parameters;
 
+[JsonDerivedType(typeof(InitializeParameters))]
+[JsonDerivedType(typeof(LookupParameters))]
 public record class MethodParameters : Parameters
 {
 	[JsonExtensionData]
 	public Dictionary<string, JsonElement> AdditionalProperties { get; set; } = [];
+
+	protected override bool PrintMembers(StringBuilder builder)
+	{
+		if (base.PrintMembers(builder))
+		{
+			builder.Append(", ");
+		}
+
+		builder.Append("AdditionalProperties = [");
+		bool append = false;
+		foreach (var kv in AdditionalProperties)
+		{
+			if (append)
+			{
+				builder.Append(", ");
+			}
+
+			append = true;
+			builder.Append(kv.Key);
+			builder.Append(" = ");
+			builder.Append(kv.Value);
+		}
+
+		builder.Append(']');
+		return true;
+	}
 }
 
 public record class InitializeParameters(

src/pdns-dhcp/PowerDns/PowerDnsHandler.cs

@@ -1,4 +1,5 @@
 using System.Buffers;
+using System.Collections.ObjectModel;
 using System.IO.Pipelines;
 using System.Net.Sockets;
 using System.Text.Json;
@@ -15,9 +16,34 @@ namespace pdns_dhcp.PowerDns;
 
 public class PowerDnsHandler : ConnectionHandler
 {
+	delegate MethodBase? HandlerConverter(in JsonElement element);
+
+	private static readonly ReadOnlyDictionary<string, HandlerConverter> Converters;
+
 	private readonly ILogger<PowerDnsHandler> _logger;
 	private readonly DnsRepository _repository;
 
+	static PowerDnsHandler()
+	{
+		Dictionary<string, HandlerConverter> converters = new(StringComparer.OrdinalIgnoreCase)
+		{
+			["initialize"] = ToInitialize,
+			["lookup"] = ToLookup
+		};
+
+		Converters = converters.AsReadOnly();
+
+		static InitializeMethod ToInitialize(in JsonElement element)
+		{
+			return new(element.Deserialize(PowerDnsSerializerContext.Default.InitializeParameters)!);
+		}
+
+		static LookupMethod ToLookup(in JsonElement element)
+		{
+			return new(element.Deserialize(PowerDnsSerializerContext.Default.LookupParameters)!);
+		}
+	}
+
 	public PowerDnsHandler(DnsRepository repository, ILogger<PowerDnsHandler> logger)
 	{
 		_logger = logger;
@@ -41,21 +67,48 @@ public class PowerDnsHandler : ConnectionHandler
 			foreach (var memory in read.Buffer)
 			{
 				buffer.Write(memory.Span);
-				if (ConsumeJson(buffer, json, ref state))
+				if (!ConsumeJson(buffer, json, ref state))
 				{
-					var method = JsonSerializer.Deserialize(json.WrittenSpan, PowerDnsSerializerContext.Default.Method)!;
+					continue;
-					json.Clear();
+				}
-					state = default;
 
 				Reply reply = BoolReply.False;
 				try
 				{
+					MethodBase method;
+					try
+					{
+						using var jsonDocument = JsonDocument.Parse(json.WrittenMemory);
+						var root = jsonDocument.RootElement;
+						if (!root.TryGetProperty("method", out var methodElement))
+						{
+							_logger.LogWarning("Json Document missing required property method: {document}", jsonDocument);
+							continue;
+						}
+
+						if (Parse(methodElement, root.GetProperty("parameters")) is not { } methodLocal)
+						{
+							continue;
+						}
+
+						method = methodLocal;
+					}
+					finally
+					{
+						json.Clear();
+						state = default;
+					}
+
 					reply = await Handle(method, connection.ConnectionClosed).ConfigureAwait(false);
 				}
-					catch (Exception e) { }
+				catch (Exception e)
-
+				{
+					_logger.LogError(e, "Error");
+				}
+				finally
+				{
 					await JsonSerializer.SerializeAsync(writer, reply, PowerDnsSerializerContext.Default.Reply, connection.ConnectionClosed)
-						.ConfigureAwait(continueOnCapturedContext: false);
+						.ConfigureAwait(false);
 				}
 			}
 
@@ -111,9 +164,20 @@ public class PowerDnsHandler : ConnectionHandler
 
 			return final;
 		}
+
+		static MethodBase? Parse(in JsonElement element, in JsonElement parameters)
+		{
+			HandlerConverter? converter = default;
+			return element.GetString() switch
+			{
+				null => null,
+				{ } methodName when !Converters.TryGetValue(methodName, out converter) => new Method<MethodParameters>(methodName, parameters.Deserialize(PowerDnsSerializerContext.Default.MethodParameters)!),
+				_ => converter(parameters)
+			};
+		}
 	}
 
-	private ValueTask<Reply> Handle(Method method, CancellationToken cancellationToken = default)
+	private ValueTask<Reply> Handle(MethodBase method, CancellationToken cancellationToken = default)
 	{
 		return method switch
 		{
@@ -123,15 +187,20 @@ public class PowerDnsHandler : ConnectionHandler
 			_ => LogUnhandled(_logger, method)
 		};
 
-		static ValueTask<Reply> LogUnhandled(ILogger logger, Method method)
+		static ValueTask<Reply> LogUnhandled(ILogger logger, MethodBase method)
 		{
-			logger.LogWarning("Unhandled Method {Method}", method);
+			logger.LogWarning("Unhandled {Method}", method);
 			return ValueTask.FromResult<Reply>(BoolReply.False);
 		}
 	}
 
 	private ValueTask<Reply> HandleInitialize(InitializeParameters parameters)
 	{
+		if (_logger.IsEnabled(LogLevel.Information))
+		{
+			_logger.LogInformation("Handling {parameters}", parameters);
+		}
+
 		return ValueTask.FromResult<Reply>(BoolReply.True);
 	}
 
@@ -151,6 +220,11 @@ public class PowerDnsHandler : ConnectionHandler
 			return ValueTask.FromResult<Reply>(BoolReply.False);
 		}
 
+		if (_logger.IsEnabled(LogLevel.Information))
+		{
+			_logger.LogInformation("Lookup {key} in {family}", parameters.Qname, parameters.Qtype);
+		}
+
 		return FindByName(((AddressFamily)qtype, parameters.Qname.AsMemory()), _repository, _logger);
 
 		static async ValueTask<Reply> FindByName((AddressFamily Family, ReadOnlyMemory<char> Qname) query, DnsRepository repository, ILogger logger)

src/pdns-dhcp/PowerDns/PowerDnsSerializerContext.cs

@@ -3,8 +3,7 @@ using System.Text.Json.Serialization;
 namespace pdns_dhcp.PowerDns;
 
 [JsonSerializable(typeof(Reply))]
-[JsonSerializable(typeof(Method))]
+[JsonSerializable(typeof(MethodParameters))]
-[JsonSerializable(typeof(Parameters))]
 [JsonSourceGenerationOptions(
 	DefaultIgnoreCondition = JsonIgnoreCondition.WhenWritingNull,
 	NumberHandling = JsonNumberHandling.AllowReadingFromString,

src/pdns-dhcp/Program.cs

@@ -60,11 +60,6 @@ builder.Services.Configure<SocketTransportOptions>(options =>
 
 builder.WebHost.ConfigureKestrel((context, options) =>
 {
-	if (context.Configuration.GetRequiredSection("PowerDns:Listener").Get<PowerDnsListenerOptions>() is { } pdnsOptions)
-	{
-		var path = PathEx.ExpandPath(pdnsOptions.Socket);
-		FileInfo file = new(path);
-		file.Directory!.Create();
 	bool isSystemd = false;
 	options.UseSystemd(options =>
 	{
@@ -72,15 +67,17 @@ builder.WebHost.ConfigureKestrel((context, options) =>
 		options.UseConnectionHandler<PowerDnsHandler>();
 	});
 	
-		if (!isSystemd)
+	if (!isSystemd && context.Configuration.GetRequiredSection("PowerDns:Listener").Get<PowerDnsListenerOptions>() is { } pdnsOptions)
 	{
+		var path = PathEx.ExpandPath(pdnsOptions.Socket);
+		FileInfo file = new(path);
+		file.Directory!.Create();
 		file.Delete();
 		options.ListenUnixSocket(path, options =>
 		{
 			options.UseConnectionHandler<PowerDnsHandler>();
 		});
 	}
-	}
 });
 
 var app = builder.Build();

src/pdns-dhcp/Services/DhcpWatcher.cs

@@ -45,6 +45,6 @@ public class DhcpWatcher : IHostedService
 		var waitTask = Task.WhenAll(tasks);
 		TaskCompletionSource taskCompletionSource = new();
 		using var registration = cancellationToken.Register(s => ((TaskCompletionSource)s!).SetCanceled(), taskCompletionSource);
-		await Task.WhenAny(waitTask, taskCompletionSource.Task).ConfigureAwait(continueOnCapturedContext: false);
+		await Task.WhenAny(waitTask, taskCompletionSource.Task).ConfigureAwait(false);
 	}
 }

src/pdns-dhcp/appsettings.Development.json

@@ -2,10 +2,10 @@
 	"Dhcp": {
 		"Kea": {
 			"Dhcp4": {
-				"Leases": "../../ext/kea/dhcp4.leases"
+				"Leases": "../../ext/kea/kea-leases4.csv"
 			},
 			"Dhcp6": {
-				"Leases": "../../ext/kea/dhcp6.leases"
+				"Leases": "../../ext/kea/kea-leases6.csv"
 			}
 		}
 	},

src/pdns-dhcp/appsettings.json

@@ -2,10 +2,10 @@
 	"Dhcp": {
 		"Kea": {
 			"Dhcp4": {
-				"Leases": "/var/lib/kea/dhcp4.leases"
+				"Leases": "/var/lib/kea/kea-leases4.csv"
 			},
 			"Dhcp6": {
-				"Leases": "/var/lib/kea/dhcp6.leases"
+				"Leases": "/var/lib/kea/kea-leases6.csv"
 			}
 		}
 	},

src/pdns-dhcp/pdns-dhcp.csproj

@@ -15,9 +15,8 @@
 
 	<ItemGroup>
 		<PackageReference Include="CommunityToolkit.HighPerformance" Version="8.2.2" />
-		<PackageReference Include="DotNext.Threading" Version="4.15.2" />
+		<PackageReference Include="DotNext" Version="4.15.2" />
 		<PackageReference Include="Microsoft.Extensions.Configuration.Binder" Version="8.0.0" PrivateAssets="all" />
-		<PackageReference Include="Microsoft.Extensions.Hosting" Version="8.0.0" />
 		<PackageReference Include="Microsoft.Extensions.Hosting.Systemd" Version="8.0.0" />
 		<PackageReference Include="Sep" Version="0.4.0" />
 		<PackageReference Include="System.IO.Pipelines" Version="8.0.0" />