feat(connector): add optional debugging targets

src/Thinktecture.Relay.Connector/DependencyInjection/RelayConnectorBuilderExtensions.cs

@@ -0,0 +1,55 @@
+using Thinktecture.Relay.Acknowledgement;
+using Thinktecture.Relay.Connector.DependencyInjection;
+using Thinktecture.Relay.Connector.Targets;
+using Thinktecture.Relay.Transport;
+
+// ReSharper disable once CheckNamespace; (extension methods on IServiceCollection namespace)
+namespace Microsoft.Extensions.DependencyInjection;
+
+/// <summary>
+/// Extension methods for the <see cref="IRelayConnectorBuilder{TRequest,TResponse,TAcknowledge}"/>.
+/// </summary>
+public static class RelayConnectorBuilderExtensions
+{
+	/// <summary>
+	/// Adds the <see cref="PingTarget{TRequest,TResponse}"/>.
+	/// </summary>
+	/// <remarks>The default target key is "$ping".</remarks>
+	/// <param name="builder">The <see cref="IRelayConnectorBuilder{TRequest,TResponse,TAcknowledge}"/>.</param>
+	/// <param name="targetKey">The target key for the <see cref="PingTarget{TRequest,TResponse}"/>.</param>
+	/// <typeparam name="TRequest">The type of request.</typeparam>
+	/// <typeparam name="TResponse">The type of response.</typeparam>
+	/// <typeparam name="TAcknowledge">The type of acknowledge.</typeparam>
+	/// <returns>The <see cref="IRelayConnectorBuilder{TRequest,TResponse,TAcknowledge}"/>.</returns>
+	public static IRelayConnectorBuilder<TRequest, TResponse, TAcknowledge> AddPingTarget<TRequest, TResponse,
+		TAcknowledge>(this IRelayConnectorBuilder<TRequest, TResponse, TAcknowledge> builder, string targetKey = "$ping")
+		where TRequest : IClientRequest
+		where TResponse : ITargetResponse, new()
+		where TAcknowledge : IAcknowledgeRequest
+	{
+		builder.AddTarget<TRequest, TResponse, TAcknowledge, PingTarget<TRequest, TResponse>>(targetKey);
+
+		return builder;
+	}
+
+	/// <summary>
+	/// Adds the <see cref="EchoTarget{TRequest,TResponse}"/>.
+	/// </summary>
+	/// <remarks>The default target key is "$echo" and should only be added for debugging purposes.</remarks>
+	/// <param name="builder">The <see cref="IRelayConnectorBuilder{TRequest,TResponse,TAcknowledge}"/>.</param>
+	/// <param name="targetKey">The target key for the <see cref="EchoTarget{TRequest,TResponse}"/>.</param>
+	/// <typeparam name="TRequest">The type of request.</typeparam>
+	/// <typeparam name="TResponse">The type of response.</typeparam>
+	/// <typeparam name="TAcknowledge">The type of acknowledge.</typeparam>
+	/// <returns>The <see cref="IRelayConnectorBuilder{TRequest,TResponse,TAcknowledge}"/>.</returns>
+	public static IRelayConnectorBuilder<TRequest, TResponse, TAcknowledge> AddEchoTarget<TRequest, TResponse,
+		TAcknowledge>(this IRelayConnectorBuilder<TRequest, TResponse, TAcknowledge> builder, string targetKey = "$echo")
+		where TRequest : IClientRequest
+		where TResponse : ITargetResponse, new()
+		where TAcknowledge : IAcknowledgeRequest
+	{
+		builder.AddTarget<TRequest, TResponse, TAcknowledge, EchoTarget<TRequest, TResponse>>(targetKey);
+
+		return builder;
+	}
+}

src/Thinktecture.Relay.Connector/Targets/EchoTarget.cs

@@ -0,0 +1,83 @@
+using System;
+using System.IO;
+using System.Net;
+using System.Threading;
+using System.Threading.Tasks;
+using Thinktecture.Relay.Transport;
+
+namespace Thinktecture.Relay.Connector.Targets;
+
+/// <inheritdoc />
+public class EchoTarget<TRequest, TResponse> : IRelayTargetFunc<TRequest, TResponse>
+	where TRequest : IClientRequest
+	where TResponse : ITargetResponse, new()
+{
+	private class CopyStream(Stream source, long length) : Stream
+	{
+		private long _length = Math.Max(0, length);
+
+		public override void Flush()
+			=> throw new NotImplementedException();
+
+		public override int Read(byte[] buffer, int offset, int count)
+		{
+			if (Position == _length) return 0;
+
+			var read = 0;
+
+			while (read < count && Position < _length)
+			{
+				var remaining = Math.Min(_length - Position, count);
+				var available = source.Read(buffer, offset, (int)remaining);
+				if (available == 0)
+				{
+					source.Position = 0;
+				}
+
+				offset += available;
+				read += available;
+				count -= available;
+
+				Position += available;
+			}
+
+			return read;
+		}
+
+		public override long Seek(long offset, SeekOrigin origin)
+			=> throw new NotSupportedException();
+
+		public override void SetLength(long value)
+			=> _length = value;
+
+		public override void Write(byte[] buffer, int offset, int count)
+			=> throw new NotSupportedException();
+
+		public override bool CanRead => true;
+
+		public override bool CanSeek => false;
+
+		public override bool CanWrite => false;
+
+		public override long Length => _length;
+
+		public override long Position { get; set; }
+	}
+
+	/// <inheritdoc />
+	public Task<TResponse> HandleAsync(TRequest request, CancellationToken cancellationToken = default)
+	{
+		if (!request.HttpMethod.Equals("POST", StringComparison.OrdinalIgnoreCase) || request.BodyContent is null)
+			return Task.FromResult(request.CreateResponse<TResponse>(HttpStatusCode.NoContent));
+
+		var result = request.CreateResponse<TResponse>(HttpStatusCode.OK);
+
+		result.BodyContent = int.TryParse(request.Url, out var size)
+			? new CopyStream(request.BodyContent, size)
+			: request.BodyContent;
+		result.BodySize = result.BodyContent.Length;
+		result.BodyContent.Position = 0;
+
+		return Task.FromResult(result);
+	}
+}

src/Thinktecture.Relay.Connector/Targets/PingTarget.cs

@@ -0,0 +1,33 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Net;
+using System.Threading;
+using System.Threading.Tasks;
+using Thinktecture.Relay.Transport;
+
+namespace Thinktecture.Relay.Connector.Targets;
+
+/// <inheritdoc />
+public class PingTarget<TRequest, TResponse> : IRelayTargetFunc<TRequest, TResponse>
+	where TRequest : IClientRequest
+	where TResponse : ITargetResponse, new()
+{
+	/// <inheritdoc />
+	public Task<TResponse> HandleAsync(TRequest request, CancellationToken cancellationToken = default)
+	{
+		if (!request.HttpMethod.Equals("GET", StringComparison.OrdinalIgnoreCase))
+			return Task.FromResult(request.CreateResponse<TResponse>(HttpStatusCode.NotFound));
+
+		var result = request.CreateResponse<TResponse>(HttpStatusCode.OK);
+
+		result.HttpHeaders = new Dictionary<string, string[]>()
+		{
+			{ "Content-Type", ["text/plain"] },
+		};
+		result.BodyContent = new MemoryStream("PONG"u8.ToArray());
+		result.BodySize = result.BodyContent.Length;
+
+		return Task.FromResult(result);
+	}
+}

src/docker/Thinktecture.Relay.Connector.Docker/Startup.cs

@@ -25,6 +25,8 @@ public static void ConfigureServices(HostBuilderContext hostBuilderContext, ISer
 		services
 			.AddRelayConnector(options => configuration.GetSection("RelayConnector").Bind(options))
 			.AddSignalRConnectorTransport()
+			.AddPingTarget()
+			.AddEchoTarget()
 			.AddTarget<InProcFunc>("inprocfunc")
 			.AddTarget<InProcAction>("inprocaction");