Rework message replies

.dockerignore

@@ -0,0 +1,9 @@
+# Ignore hidden files
+.*
+
+# Include .git for build version information
+!.git
+
+# Not needed for building
+AddMigration.*
+*.DotSettings.user

.run/Agent 1.run.xml

@@ -5,13 +5,13 @@
     <option name="WORKING_DIRECTORY" value="$PROJECT_DIR$/.workdir/Agent1" />
     <option name="PASS_PARENT_ENVS" value="1" />
     <envs>
+      <env name="AGENT_KEY" value="JXBQQYG5T267RQS75MXWBTCJZY5CKTCCGQY22MCZPHSQQSJYCHH2NG2TCNXQY6TBSXM9NQDRS2CMX" />
       <env name="AGENT_NAME" value="Agent 1" />
       <env name="ALLOWED_RCON_PORTS" value="25575,27000,27001" />
       <env name="ALLOWED_SERVER_PORTS" value="25565,26000,26001" />
       <env name="JAVA_SEARCH_PATH" value="~/.jdks" />
       <env name="MAX_INSTANCES" value="3" />
       <env name="MAX_MEMORY" value="12G" />
-      <env name="SERVER_AUTH_TOKEN_FILE" value="./secrets/agent.token" />
       <env name="SERVER_HOST" value="localhost" />
     </envs>
     <option name="USE_EXTERNAL_CONSOLE" value="0" />

.run/Agent 2.run.xml

@@ -5,13 +5,13 @@
     <option name="WORKING_DIRECTORY" value="$PROJECT_DIR$/.workdir/Agent2" />
     <option name="PASS_PARENT_ENVS" value="1" />
     <envs>
+      <env name="AGENT_KEY" value="JXBQQYG5T267RQS75MXWBTCJZY5CKTCCGQY22MCZPHSQQSJYCHH2NG2TCNXQY6TBSXM9NQDRS2CMX" />
       <env name="AGENT_NAME" value="Agent 2" />
       <env name="ALLOWED_RCON_PORTS" value="27002-27006" />
       <env name="ALLOWED_SERVER_PORTS" value="26002-26006" />
       <env name="JAVA_SEARCH_PATH" value="~/.jdks" />
       <env name="MAX_INSTANCES" value="5" />
       <env name="MAX_MEMORY" value="10G" />
-      <env name="SERVER_AUTH_TOKEN_FILE" value="./secrets/agent.token" />
       <env name="SERVER_HOST" value="localhost" />
     </envs>
     <option name="USE_EXTERNAL_CONSOLE" value="0" />

.run/Agent 3.run.xml

@@ -5,13 +5,13 @@
     <option name="WORKING_DIRECTORY" value="$PROJECT_DIR$/.workdir/Agent3" />
     <option name="PASS_PARENT_ENVS" value="1" />
     <envs>
+      <env name="AGENT_KEY" value="JXBQQYG5T267RQS75MXWBTCJZY5CKTCCGQY22MCZPHSQQSJYCHH2NG2TCNXQY6TBSXM9NQDRS2CMX" />
       <env name="AGENT_NAME" value="Agent 3" />
       <env name="ALLOWED_RCON_PORTS" value="27007" />
       <env name="ALLOWED_SERVER_PORTS" value="26007" />
       <env name="JAVA_SEARCH_PATH" value="~/.jdks" />
       <env name="MAX_INSTANCES" value="1" />
       <env name="MAX_MEMORY" value="2560M" />
-      <env name="SERVER_AUTH_TOKEN_FILE" value="./secrets/agent.token" />
       <env name="SERVER_HOST" value="localhost" />
     </envs>
     <option name="USE_EXTERNAL_CONSOLE" value="0" />

.workdir/.gitignore

@@ -1,2 +0,0 @@
-/Agent*/data
-/Agent*/temp

.workdir/Agent1/.gitignore

@@ -0,0 +1,2 @@
+*
+!.gitignore

.workdir/Agent1/secrets/agent.key

@@ -1 +0,0 @@
-tLkn<EFBFBD>Z<EFBFBD><EFBFBD>}ы<><D18B>|~2<><32>><3E><>р<EFBFBD><D180>O*<2A>	p

.workdir/Agent1/secrets/agent.token

@@ -1 +0,0 @@
-TH7Z2MJKMR975N6HFBKQP9WQFMWWN5

.workdir/Agent2/.gitignore

@@ -0,0 +1,2 @@
+*
+!.gitignore

.workdir/Agent2/secrets/agent.key

@@ -1 +0,0 @@
-tLkn<EFBFBD>Z<EFBFBD><EFBFBD>}ы<><D18B>|~2<><32>><3E><>р<EFBFBD><D180>O*<2A>	p

.workdir/Agent2/secrets/agent.token

@@ -1 +0,0 @@
-TH7Z2MJKMR975N6HFBKQP9WQFMWWN5

.workdir/Agent3/.gitignore

@@ -0,0 +1,2 @@
+*
+!.gitignore

.workdir/Agent3/secrets/agent.key

@@ -1 +0,0 @@
-tLkn<EFBFBD>Z<EFBFBD><EFBFBD>}ы<><D18B>|~2<><32>><3E><>р<EFBFBD><D180>O*<2A>	p

.workdir/Agent3/secrets/agent.token

@@ -1 +0,0 @@
-TH7Z2MJKMR975N6HFBKQP9WQFMWWN5

.workdir/Server/.gitignore

@@ -0,0 +1 @@
+/keys

.workdir/Server/secrets/agent.token

@@ -1 +0,0 @@
-TH7Z2MJKMR975N6HFBKQP9WQFMWWN5

.workdir/Server/secrets/secret.key

@@ -1 +1 @@
-+<2B><><EFBFBD><EFBFBD><<3C>f:<3A>bJ"e<18>׸ބ<D7B8><1F><><EFBFBD><EFBFBD> <20><><EFBFBD><EFBFBD>
+<EFBFBD>Z<EFBFBD>t<>MPI<49>GMZ<4D><5A><EFBFBD><EFBFBD>kN<6B>VF1X<EFBFBD><EFBFBD>p

Agent/Phantom.Agent.Minecraft/Command/MinecraftCommand.cs

@@ -0,0 +1,9 @@
+namespace Phantom.Agent.Minecraft.Command; 
+
+public static class MinecraftCommand {
+	public const string Stop = "stop";
+
+	public static string Say(string message) {
+		return "say " + message;
+	}
+}

Agent/Phantom.Agent.Minecraft/Instance/InstanceProperties.cs

@@ -1,4 +1,5 @@
-using Phantom.Agent.Minecraft.Java;
+using System.Collections.Immutable;
+using Phantom.Agent.Minecraft.Java;
 using Phantom.Agent.Minecraft.Properties;
 
 namespace Phantom.Agent.Minecraft.Instance;
@@ -6,6 +7,7 @@ namespace Phantom.Agent.Minecraft.Instance;
 public sealed record InstanceProperties(
 	Guid JavaRuntimeGuid,
 	JvmProperties JvmProperties,
+	ImmutableArray<string> JvmArguments,
 	string InstanceFolder,
 	string ServerVersion,
 	ServerProperties ServerProperties

Agent/Phantom.Agent.Minecraft/Java/JavaRuntimeDiscovery.cs

@@ -38,28 +38,38 @@ public sealed class JavaRuntimeDiscovery {
 			AttributesToSkip = FileAttributes.Hidden | FileAttributes.ReparsePoint | FileAttributes.System
 		}).Order()) {
 			var javaExecutablePath = Paths.NormalizeSlashes(Path.Combine(binFolderPath, javaExecutableName));
-			if (File.Exists(javaExecutablePath)) {
-				Logger.Information("Found candidate Java executable: {JavaExecutablePath}", javaExecutablePath);
-
-				JavaRuntime? foundRuntime;
-				try {
-					foundRuntime = await TryReadJavaRuntimeInformationFromProcess(javaExecutablePath);
-				} catch (OperationCanceledException) {
-					Logger.Error("Java process did not exit in time.");
-					continue;
-				} catch (Exception e) {
-					Logger.Error(e, "Caught exception while reading Java version information.");
-					continue;
-				}
-
-				if (foundRuntime == null) {
-					Logger.Error("Java executable did not output version information.");
-					continue;
-				}
-
-				Logger.Information("Found Java {DisplayName} at: {Path}", foundRuntime.DisplayName, javaExecutablePath);
-				yield return new JavaRuntimeExecutable(javaExecutablePath, foundRuntime);
+			
+			FileAttributes javaExecutableAttributes;
+			try {
+				javaExecutableAttributes = File.GetAttributes(javaExecutablePath);
+			} catch (Exception) {
+				continue;
 			}
+
+			if (javaExecutableAttributes.HasFlag(FileAttributes.ReparsePoint)) {
+				continue;
+			}
+
+			Logger.Information("Found candidate Java executable: {JavaExecutablePath}", javaExecutablePath);
+
+			JavaRuntime? foundRuntime;
+			try {
+				foundRuntime = await TryReadJavaRuntimeInformationFromProcess(javaExecutablePath);
+			} catch (OperationCanceledException) {
+				Logger.Error("Java process did not exit in time.");
+				continue;
+			} catch (Exception e) {
+				Logger.Error(e, "Caught exception while reading Java version information.");
+				continue;
+			}
+
+			if (foundRuntime == null) {
+				Logger.Error("Java executable did not output version information.");
+				continue;
+			}
+
+			Logger.Information("Found Java {DisplayName} at: {Path}", foundRuntime.DisplayName, javaExecutablePath);
+			yield return new JavaRuntimeExecutable(javaExecutablePath, foundRuntime);
 		}
 	}
 

Agent/Phantom.Agent.Minecraft/Java/JvmArgumentBuilder.cs

@@ -1,25 +1,31 @@
-using System.Collections.ObjectModel;
+using System.Collections.Immutable;
+using System.Collections.ObjectModel;
 
 namespace Phantom.Agent.Minecraft.Java;
 
 sealed class JvmArgumentBuilder {
 	private readonly JvmProperties basicProperties;
-	private readonly List<string> customProperties = new ();
+	private readonly List<string> customArguments = new ();
 
-	public JvmArgumentBuilder(JvmProperties basicProperties) {
+	public JvmArgumentBuilder(JvmProperties basicProperties, ImmutableArray<string> customArguments) {
 		this.basicProperties = basicProperties;
+
+		foreach (var jvmArgument in customArguments) {
+			this.customArguments.Add(jvmArgument);
+		}
 	}
 
 	public void AddProperty(string key, string value) {
-		customProperties.Add("-D" + key + "=\"" + value + "\""); // TODO test quoting?
+		customArguments.Add("-D" + key + "=\"" + value + "\""); // TODO test quoting?
 	}
 
 	public void Build(Collection<string> target) {
-		target.Add("-Xms" + basicProperties.InitialHeapMegabytes + "M");
-		target.Add("-Xmx" + basicProperties.MaximumHeapMegabytes + "M");
-
-		foreach (var property in customProperties) {
+		foreach (var property in customArguments) {
 			target.Add(property);
 		}
+
+		target.Add("-Xms" + basicProperties.InitialHeapMegabytes + "M");
+		target.Add("-Xmx" + basicProperties.MaximumHeapMegabytes + "M");
+		target.Add("-Xrs");
 	}
 }

Agent/Phantom.Agent.Minecraft/Launcher/BaseLauncher.cs

@@ -4,6 +4,8 @@ using Kajabity.Tools.Java;
 using Phantom.Agent.Minecraft.Instance;
 using Phantom.Agent.Minecraft.Java;
 using Phantom.Agent.Minecraft.Server;
+using Phantom.Common.Minecraft;
+using Serilog;
 
 namespace Phantom.Agent.Minecraft.Launcher;
 
@@ -14,11 +16,15 @@ public abstract class BaseLauncher {
 		this.instanceProperties = instanceProperties;
 	}
 
-	public async Task<LaunchResult> Launch(LaunchServices services, EventHandler<DownloadProgressEventArgs> downloadProgressEventHandler, CancellationToken cancellationToken) {
+	public async Task<LaunchResult> Launch(ILogger logger, LaunchServices services, EventHandler<DownloadProgressEventArgs> downloadProgressEventHandler, CancellationToken cancellationToken) {
 		if (!services.JavaRuntimeRepository.TryGetByGuid(instanceProperties.JavaRuntimeGuid, out var javaRuntimeExecutable)) {
 			return new LaunchResult.InvalidJavaRuntime();
 		}
 
+		if (JvmArgumentsHelper.Validate(instanceProperties.JvmArguments) != null) {
+			return new LaunchResult.InvalidJvmArguments();
+		}
+
 		var vanillaServerJarPath = await services.ServerExecutables.DownloadAndGetPath(instanceProperties.ServerVersion, downloadProgressEventHandler, cancellationToken);
 		if (vanillaServerJarPath == null) {
 			return new LaunchResult.CouldNotDownloadMinecraftServer();
@@ -33,8 +39,8 @@ public abstract class BaseLauncher {
 			UseShellExecute = false,
 			CreateNoWindow = false
 		};
-
-		var jvmArguments = new JvmArgumentBuilder(instanceProperties.JvmProperties);
+		
+		var jvmArguments = new JvmArgumentBuilder(instanceProperties.JvmProperties, instanceProperties.JvmArguments);
 		CustomizeJvmArguments(jvmArguments);
 
 		var serverJarPath = await PrepareServerJar(vanillaServerJarPath, instanceProperties.InstanceFolder, cancellationToken);
@@ -47,12 +53,29 @@ public abstract class BaseLauncher {
 		var process = new Process { StartInfo = startInfo };
 		var session = new InstanceSession(process);
 
-		await AcceptEula(instanceProperties);
-		await UpdateServerProperties(instanceProperties);
+		try {
+			await AcceptEula(instanceProperties);
+			await UpdateServerProperties(instanceProperties);
+		} catch (Exception e) {
+			logger.Error(e, "Caught exception while configuring the server.");
+			return new LaunchResult.CouldNotConfigureMinecraftServer();
+		}
 
-		process.Start();
-		process.BeginOutputReadLine();
-		process.BeginErrorReadLine();
+		try {
+			process.Start();
+			process.BeginOutputReadLine();
+			process.BeginErrorReadLine();
+		} catch (Exception launchException) {
+			logger.Error(launchException, "Caught exception launching the server process.");
+			
+			try {
+				process.Kill();
+			} catch (Exception killException) {
+				logger.Error(killException, "Caught exception trying to kill the server process after a failed launch.");
+			}
+
+			return new LaunchResult.CouldNotStartMinecraftServer();
+		}
 
 		return new LaunchResult.Success(session);
 	}
@@ -72,16 +95,18 @@ public abstract class BaseLauncher {
 		var serverPropertiesFilePath = Path.Combine(instanceProperties.InstanceFolder, "server.properties");
 		var serverPropertiesData = new JavaProperties();
 
+		await using var fileStream = new FileStream(serverPropertiesFilePath, FileMode.OpenOrCreate, FileAccess.ReadWrite, FileShare.None);
 		try {
-			await using var readStream = new FileStream(serverPropertiesFilePath, FileMode.Open, FileAccess.Read, FileShare.Read);
-			serverPropertiesData.Load(readStream);
-		} catch (FileNotFoundException) {
-			// ignore
+			serverPropertiesData.Load(fileStream);
+		} catch (ParseException e) {
+			throw new Exception("Could not parse server.properties file: " + serverPropertiesFilePath, e);
 		}
 		
 		instanceProperties.ServerProperties.SetTo(serverPropertiesData);
 
-		await using var writeStream = new FileStream(serverPropertiesFilePath, FileMode.OpenOrCreate, FileAccess.Write, FileShare.None);
-		serverPropertiesData.Store(writeStream, true);
+		fileStream.Seek(0L, SeekOrigin.Begin);
+		fileStream.SetLength(0L);
+		
+		serverPropertiesData.Store(fileStream, true);
 	}
 }

Agent/Phantom.Agent.Minecraft/Launcher/LaunchResult.cs

@@ -8,6 +8,12 @@ public abstract record LaunchResult {
 	public sealed record Success(InstanceSession Session) : LaunchResult;
 
 	public sealed record InvalidJavaRuntime : LaunchResult;
+	
+	public sealed record InvalidJvmArguments : LaunchResult;
 
 	public sealed record CouldNotDownloadMinecraftServer : LaunchResult;
+	
+	public sealed record CouldNotConfigureMinecraftServer : LaunchResult;
+	
+	public sealed record CouldNotStartMinecraftServer : LaunchResult;
 }

Agent/Phantom.Agent.Minecraft/Launcher/LaunchServices.cs

@@ -1,6 +1,7 @@
 using Phantom.Agent.Minecraft.Java;
 using Phantom.Agent.Minecraft.Server;
+using Phantom.Utils.Runtime;
 
 namespace Phantom.Agent.Minecraft.Launcher; 
 
-public sealed record LaunchServices(MinecraftServerExecutables ServerExecutables, JavaRuntimeRepository JavaRuntimeRepository);
+public sealed record LaunchServices(TaskManager TaskManager, MinecraftServerExecutables ServerExecutables, JavaRuntimeRepository JavaRuntimeRepository);

Agent/Phantom.Agent.Minecraft/Phantom.Agent.Minecraft.csproj

@@ -7,15 +7,17 @@
   </PropertyGroup>
   
   <ItemGroup>
-    <PackageReference Include="Kajabity.Tools.Java" Version="0.3.7879.40798" />
+    <PackageReference Include="Kajabity.Tools.Java" />
   </ItemGroup>
   
   <ItemGroup>
     <ProjectReference Include="..\..\Common\Phantom.Common.Data\Phantom.Common.Data.csproj" />
     <ProjectReference Include="..\..\Common\Phantom.Common.Logging\Phantom.Common.Logging.csproj" />
+    <ProjectReference Include="..\..\Common\Phantom.Common.Minecraft\Phantom.Common.Minecraft.csproj" />
     <ProjectReference Include="..\..\Utils\Phantom.Utils.Collections\Phantom.Utils.Collections.csproj" />
     <ProjectReference Include="..\..\Utils\Phantom.Utils.Cryptography\Phantom.Utils.Cryptography.csproj" />
     <ProjectReference Include="..\..\Utils\Phantom.Utils.IO\Phantom.Utils.IO.csproj" />
+    <ProjectReference Include="..\..\Utils\Phantom.Utils.Runtime\Phantom.Utils.Runtime.csproj" />
   </ItemGroup>
 
 </Project>

Agent/Phantom.Agent.Minecraft/Server/MinecraftServerExecutableDownloader.cs

@@ -1,9 +1,9 @@
-using System.Net.Http.Json;
-using System.Security.Cryptography;
-using System.Text.Json;
+using System.Security.Cryptography;
 using Phantom.Common.Logging;
+using Phantom.Common.Minecraft;
 using Phantom.Utils.Cryptography;
 using Phantom.Utils.IO;
+using Phantom.Utils.Runtime;
 using Serilog;
 
 namespace Phantom.Agent.Minecraft.Server;
@@ -11,8 +11,8 @@ namespace Phantom.Agent.Minecraft.Server;
 sealed class MinecraftServerExecutableDownloader {
 	private static readonly ILogger Logger = PhantomLogger.Create<MinecraftServerExecutableDownloader>();
 
-	private const string VersionManifestUrl = "https://launchermeta.mojang.com/mc/game/version_manifest.json";
-
+	private readonly MinecraftVersions minecraftVersions;
+	
 	public Task<string?> Task { get; }
 	public event EventHandler<DownloadProgressEventArgs>? DownloadProgress;
 	public event EventHandler? Completed;
@@ -20,7 +20,9 @@ sealed class MinecraftServerExecutableDownloader {
 	private readonly CancellationTokenSource cancellationTokenSource = new ();
 	private int listeners = 0;
 
-	public MinecraftServerExecutableDownloader(string version, string filePath, MinecraftServerExecutableDownloadListener listener) {
+	public MinecraftServerExecutableDownloader(MinecraftVersions minecraftVersions, string version, string filePath, MinecraftServerExecutableDownloadListener listener) {
+		this.minecraftVersions = minecraftVersions;
+		
 		Register(listener);
 		Task = DownloadAndGetPath(version, filePath);
 		Task.ContinueWith(OnCompleted, TaskScheduler.Default);
@@ -73,21 +75,18 @@ sealed class MinecraftServerExecutableDownloader {
 	private async Task<string?> DownloadAndGetPath(string version, string filePath) {
 		Logger.Information("Downloading server version {Version}...", version);
 
-		HttpClient http = new HttpClient();
 		string tmpFilePath = filePath + ".tmp";
 
 		var cancellationToken = cancellationTokenSource.Token;
 		try {
-			Logger.Information("Fetching version manifest from: {Url}", VersionManifestUrl);
-			var versionManifest = await FetchVersionManifest(http, cancellationToken);
-			var metadataUrl = GetVersionMetadataUrlFromManifest(version, versionManifest);
-
-			Logger.Information("Fetching metadata for version {Version} from: {Url}", version, metadataUrl);
-			var versionMetadata = await FetchVersionMetadata(http, metadataUrl, cancellationToken);
-			var serverExecutableInfo = GetServerExecutableUrlFromMetadata(versionMetadata);
+			var serverExecutableInfo = await minecraftVersions.GetServerExecutableInfo(version, cancellationToken);
+			if (serverExecutableInfo == null) {
+				return null;
+			}
 
 			Logger.Information("Downloading server executable from: {Url} ({Size})", serverExecutableInfo.DownloadUrl, serverExecutableInfo.Size.ToHumanReadable(decimalPlaces: 1));
 			try {
+				using var http = new HttpClient();
 				await FetchServerExecutableFile(http, new DownloadProgressCallback(this), serverExecutableInfo, tmpFilePath, cancellationToken);
 			} catch (Exception) {
 				TryDeleteExecutableAfterFailure(tmpFilePath);
@@ -111,31 +110,7 @@ sealed class MinecraftServerExecutableDownloader {
 		}
 	}
 
-	private static async Task<JsonElement> FetchVersionManifest(HttpClient http, CancellationToken cancellationToken) {
-		try {
-			return await http.GetFromJsonAsync<JsonElement>(VersionManifestUrl, cancellationToken);
-		} catch (HttpRequestException e) {
-			Logger.Error(e, "Unable to download version manifest.");
-			throw StopProcedureException.Instance;
-		} catch (Exception e) {
-			Logger.Error(e, "Unable to parse version manifest as JSON.");
-			throw StopProcedureException.Instance;
-		}
-	}
-
-	private static async Task<JsonElement> FetchVersionMetadata(HttpClient http, string metadataUrl, CancellationToken cancellationToken) {
-		try {
-			return await http.GetFromJsonAsync<JsonElement>(metadataUrl, cancellationToken);
-		} catch (HttpRequestException e) {
-			Logger.Error(e, "Unable to download version metadata.");
-			throw StopProcedureException.Instance;
-		} catch (Exception e) {
-			Logger.Error(e, "Unable to parse version metadata as JSON.");
-			throw StopProcedureException.Instance;
-		}
-	}
-
-	private static async Task FetchServerExecutableFile(HttpClient http, DownloadProgressCallback progressCallback, ServerExecutableInfo info, string filePath, CancellationToken cancellationToken) {
+	private static async Task FetchServerExecutableFile(HttpClient http, DownloadProgressCallback progressCallback, MinecraftServerExecutableInfo info, string filePath, CancellationToken cancellationToken) {
 		Sha1String downloadedFileHash;
 
 		try {
@@ -170,83 +145,6 @@ sealed class MinecraftServerExecutableDownloader {
 		}
 	}
 
-	private static string GetVersionMetadataUrlFromManifest(string serverVersion, JsonElement versionManifest) {
-		JsonElement versionsElement = GetJsonPropertyOrThrow(versionManifest, "versions", JsonValueKind.Array, "version manifest");
-		JsonElement versionElement;
-		try {
-			versionElement = versionsElement.EnumerateArray().Single(ele => ele.TryGetProperty("id", out var id) && id.ValueKind == JsonValueKind.String && id.GetString() == serverVersion);
-		} catch (Exception) {
-			Logger.Error("Version {Version} was not found in version manifest.", serverVersion);
-			throw StopProcedureException.Instance;
-		}
-
-		JsonElement urlElement = GetJsonPropertyOrThrow(versionElement, "url", JsonValueKind.String, "version entry in version manifest");
-		string? url = urlElement.GetString();
-
-		if (!Uri.TryCreate(url, UriKind.Absolute, out var uri)) {
-			Logger.Error("The \"url\" key in version entry in version manifest does not contain a valid URL: {Url}", url);
-			throw StopProcedureException.Instance;
-		}
-
-		if (uri.Scheme != "https" || !uri.AbsolutePath.EndsWith(".json", StringComparison.OrdinalIgnoreCase)) {
-			Logger.Error("The \"url\" key in version entry in version manifest does not contain a accepted URL: {Url}", url);
-			throw StopProcedureException.Instance;
-		}
-
-		return url;
-	}
-
-	private static ServerExecutableInfo GetServerExecutableUrlFromMetadata(JsonElement versionMetadata) {
-		JsonElement downloadsElement = GetJsonPropertyOrThrow(versionMetadata, "downloads", JsonValueKind.Object, "version metadata");
-		JsonElement serverElement = GetJsonPropertyOrThrow(downloadsElement, "server", JsonValueKind.Object, "downloads object in version metadata");
-		JsonElement urlElement = GetJsonPropertyOrThrow(serverElement, "url", JsonValueKind.String, "downloads.server object in version metadata");
-		string? url = urlElement.GetString();
-
-		if (!Uri.TryCreate(url, UriKind.Absolute, out var uri)) {
-			Logger.Error("The \"url\" key in downloads.server object in version metadata does not contain a valid URL: {Url}", url);
-			throw StopProcedureException.Instance;
-		}
-
-		if (uri.Scheme != "https" || !uri.AbsolutePath.EndsWith(".jar", StringComparison.OrdinalIgnoreCase)) {
-			Logger.Error("The \"url\" key in downloads.server object in version metadata does not contain a accepted URL: {Url}", url);
-			throw StopProcedureException.Instance;
-		}
-
-		JsonElement sizeElement = GetJsonPropertyOrThrow(serverElement, "size", JsonValueKind.Number, "downloads.server object in version metadata");
-		ulong size;
-		try {
-			size = sizeElement.GetUInt64();
-		} catch (FormatException) {
-			Logger.Error("The \"size\" key in downloads.server object in version metadata contains an invalid file size: {Size}", sizeElement);
-			throw StopProcedureException.Instance;
-		}
-
-		JsonElement sha1Element = GetJsonPropertyOrThrow(serverElement, "sha1", JsonValueKind.String, "downloads.server object in version metadata");
-		Sha1String hash;
-		try {
-			hash = Sha1String.FromString(sha1Element.GetString());
-		} catch (Exception) {
-			Logger.Error("The \"sha1\" key in downloads.server object in version metadata does not contain a valid SHA-1 hash: {Sha1}", sha1Element.GetString());
-			throw StopProcedureException.Instance;
-		}
-
-		return new ServerExecutableInfo(url, hash, new FileSize(size));
-	}
-
-	private static JsonElement GetJsonPropertyOrThrow(JsonElement parentElement, string propertyKey, JsonValueKind expectedKind, string location) {
-		if (!parentElement.TryGetProperty(propertyKey, out var valueElement)) {
-			Logger.Error("Missing \"{Property}\" key in " + location + ".", propertyKey);
-			throw StopProcedureException.Instance;
-		}
-
-		if (valueElement.ValueKind != expectedKind) {
-			Logger.Error("The \"{Property}\" key in " + location + " does not contain a JSON {ExpectedType}. Actual type: {ActualType}", propertyKey, expectedKind, valueElement.ValueKind);
-			throw StopProcedureException.Instance;
-		}
-
-		return valueElement;
-	}
-
 	private sealed class MinecraftServerDownloadStreamCopier : IDisposable {
 		private readonly StreamCopier streamCopier = new ();
 		private readonly IncrementalHash sha1 = IncrementalHash.CreateHash(HashAlgorithmName.SHA1);
@@ -278,10 +176,4 @@ sealed class MinecraftServerExecutableDownloader {
 			streamCopier.Dispose();
 		}
 	}
-
-	private sealed class StopProcedureException : Exception {
-		public static StopProcedureException Instance { get; } = new ();
-
-		private StopProcedureException() {}
-	}
 }

Agent/Phantom.Agent.Minecraft/Server/MinecraftServerExecutables.cs

@@ -1,15 +1,18 @@
 using System.Text.RegularExpressions;
 using Phantom.Common.Logging;
+using Phantom.Common.Minecraft;
+using Phantom.Utils.IO;
 using Serilog;
 
 namespace Phantom.Agent.Minecraft.Server;
 
-public sealed class MinecraftServerExecutables {
+public sealed class MinecraftServerExecutables : IDisposable {
 	private static readonly ILogger Logger = PhantomLogger.Create<MinecraftServerExecutables>();
 
 	private static readonly Regex VersionFolderSanitizeRegex = new (@"[^a-zA-Z0-9_\-\.]", RegexOptions.Compiled);
 
 	private readonly string basePath;
+	private readonly MinecraftVersions minecraftVersions = new ();
 	private readonly Dictionary<string, MinecraftServerExecutableDownloader> runningDownloadersByVersion = new ();
 
 	public MinecraftServerExecutables(string basePath) {
@@ -25,7 +28,7 @@ public sealed class MinecraftServerExecutables {
 		}
 
 		try {
-			Directory.CreateDirectory(serverExecutableFolderPath);
+			Directories.Create(serverExecutableFolderPath, Chmod.URWX_GRX);
 		} catch (Exception e) {
 			Logger.Error(e, "Unable to create folder for server executable: {ServerExecutableFolderPath}", serverExecutableFolderPath);
 			return null;
@@ -40,7 +43,7 @@ public sealed class MinecraftServerExecutables {
 				downloader.Register(listener);
 			}
 			else {
-				downloader = new MinecraftServerExecutableDownloader(version, serverExecutableFilePath, listener);
+				downloader = new MinecraftServerExecutableDownloader(minecraftVersions, version, serverExecutableFilePath, listener);
 				downloader.Completed += (_, _) => {
 					lock (this) {
 						runningDownloadersByVersion.Remove(version);
@@ -53,4 +56,8 @@ public sealed class MinecraftServerExecutables {
 
 		return await downloader.Task.WaitAsync(cancellationToken);
 	}
+
+	public void Dispose() {
+		minecraftVersions.Dispose();
+	}
 }

Agent/Phantom.Agent.Rpc/KeepAliveLoop.cs

@@ -0,0 +1,41 @@
+using Phantom.Common.Logging;
+using Phantom.Common.Messages.ToServer;
+using Phantom.Utils.Runtime;
+using Serilog;
+
+namespace Phantom.Agent.Rpc;
+
+sealed class KeepAliveLoop {
+	private static readonly ILogger Logger = PhantomLogger.Create<KeepAliveLoop>();
+
+	private static readonly TimeSpan KeepAliveInterval = TimeSpan.FromSeconds(10);
+
+	private readonly RpcServerConnection connection;
+	private readonly CancellationTokenSource cancellationTokenSource = new ();
+
+	public KeepAliveLoop(RpcServerConnection connection, TaskManager taskManager) {
+		this.connection = connection;
+		taskManager.Run(Run);
+	}
+
+	private async Task Run() {
+		var cancellationToken = cancellationTokenSource.Token;
+
+		Logger.Information("Started keep-alive loop.");
+		try {
+			while (true) {
+				await Task.Delay(KeepAliveInterval, cancellationToken);
+				await connection.Send(new AgentIsAliveMessage());
+			}
+		} catch (OperationCanceledException) {
+			// Ignore.
+		} finally {
+			cancellationTokenSource.Dispose();
+			Logger.Information("Stopped keep-alive loop.");
+		}
+	}
+
+	public void Cancel() {
+		cancellationTokenSource.Cancel();
+	}
+}

Agent/Phantom.Agent.Rpc/Phantom.Agent.Rpc.csproj

@@ -6,10 +6,6 @@
     <Nullable>enable</Nullable>
   </PropertyGroup>
   
-  <ItemGroup>
-    <PackageReference Include="Serilog" Version="2.12.0" />
-  </ItemGroup>
-  
   <ItemGroup>
     <ProjectReference Include="..\..\Common\Phantom.Common.Messages\Phantom.Common.Messages.csproj" />
   </ItemGroup>

Agent/Phantom.Agent.Rpc/RpcExtensions.cs

@@ -1,19 +0,0 @@
-using NetMQ;
-using NetMQ.Sockets;
-using Phantom.Common.Messages;
-using Phantom.Common.Messages.ToServer;
-
-namespace Phantom.Agent.Rpc; 
-
-public static class RpcExtensions {
-	internal static async Task SendMessage<TMessage>(this ClientSocket socket, TMessage message) where TMessage : IMessageToServer {
-		byte[] bytes = MessageRegistries.ToServer.Write(message).ToArray();
-		if (bytes.Length > 0) {
-			await socket.SendAsync(bytes);
-		}
-	}
-	
-	public static Task SendSimpleReply<TMessage, TReplyEnum>(this ClientSocket socket, TMessage message, TReplyEnum reply) where TMessage : IMessageWithReply where TReplyEnum : Enum {
-		return SendMessage(socket, SimpleReplyMessage.FromEnum(message.SequenceId, reply));
-	}
-}

Agent/Phantom.Agent.Rpc/RpcLauncher.cs

@@ -4,30 +4,38 @@ using Phantom.Common.Data.Agent;
 using Phantom.Common.Messages;
 using Phantom.Common.Messages.ToServer;
 using Phantom.Utils.Rpc;
+using Phantom.Utils.Rpc.Message;
+using Phantom.Utils.Runtime;
+using Serilog;
 using Serilog.Events;
 
 namespace Phantom.Agent.Rpc;
 
 public sealed class RpcLauncher : RpcRuntime<ClientSocket> {
-	public static async Task Launch(RpcConfiguration config, AgentAuthToken authToken, AgentInfo agentInfo, Func<ClientSocket, IMessageToAgentListener> listenerFactory) {
+	public static async Task Launch(RpcConfiguration config, AgentAuthToken authToken, AgentInfo agentInfo, Func<RpcServerConnection, IMessageToAgentListener> listenerFactory, SemaphoreSlim disconnectSemaphore, CancellationToken receiveCancellationToken) {
 		var socket = new ClientSocket();
 		var options = socket.Options;
 
 		options.CurveServerCertificate = config.ServerCertificate;
 		options.CurveCertificate = new NetMQCertificate();
 		options.HelloMessage = MessageRegistries.ToServer.Write(new RegisterAgentMessage(authToken, agentInfo)).ToArray();
-		
-		await new RpcLauncher(config, socket, agentInfo.Guid, listenerFactory).Launch();
+
+		await new RpcLauncher(config, socket, agentInfo.Guid, listenerFactory, disconnectSemaphore, receiveCancellationToken).Launch();
 	}
 
 	private readonly RpcConfiguration config;
 	private readonly Guid agentGuid;
-	private readonly Func<ClientSocket, IMessageToAgentListener> messageListenerFactory;
+	private readonly Func<RpcServerConnection, IMessageToAgentListener> messageListenerFactory;
 
-	private RpcLauncher(RpcConfiguration config, ClientSocket socket, Guid agentGuid, Func<ClientSocket, IMessageToAgentListener> messageListenerFactory) : base(socket, config.CancellationToken) {
+	private readonly SemaphoreSlim disconnectSemaphore;
+	private readonly CancellationToken receiveCancellationToken;
+
+	private RpcLauncher(RpcConfiguration config, ClientSocket socket, Guid agentGuid, Func<RpcServerConnection, IMessageToAgentListener> messageListenerFactory, SemaphoreSlim disconnectSemaphore, CancellationToken receiveCancellationToken) : base(socket, config.Logger) {
 		this.config = config;
 		this.agentGuid = agentGuid;
 		this.messageListenerFactory = messageListenerFactory;
+		this.disconnectSemaphore = disconnectSemaphore;
+		this.receiveCancellationToken = receiveCancellationToken;
 	}
 
 	protected override void Connect(ClientSocket socket) {
@@ -39,35 +47,60 @@ public sealed class RpcLauncher : RpcRuntime<ClientSocket> {
 		logger.Information("ZeroMQ client ready.");
 	}
 
-	protected override async Task Run(ClientSocket socket, CancellationToken cancellationToken) {
+	protected override void Run(ClientSocket socket, MessageReplyTracker replyTracker, TaskManager taskManager) {
+		var connection = new RpcServerConnection(socket, replyTracker);
+		ServerMessaging.SetCurrentConnection(connection);
+		
 		var logger = config.Logger;
-		
-		var listener = messageListenerFactory(socket);
-		
-		ServerMessaging.SetCurrentSocket(socket, cancellationToken);
+		var handler = new MessageToAgentHandler(messageListenerFactory(connection), logger, taskManager, receiveCancellationToken);
+		var keepAliveLoop = new KeepAliveLoop(connection, taskManager);
 
-		// TODO optimize msg
-		await foreach (var bytes in socket.ReceiveBytesAsyncEnumerable(cancellationToken)) {
-			if (logger.IsEnabled(LogEventLevel.Verbose)) {
-				if (bytes.Length > 0 && MessageRegistries.ToAgent.TryGetType(bytes, out var type)) {
-					logger.Verbose("Received {MessageType} ({Bytes} B) from server.", type.Name, bytes.Length);
-				}
-				else {
-					logger.Verbose("Received {Bytes} B message from server.", bytes.Length);
+		try {
+			while (!receiveCancellationToken.IsCancellationRequested) {
+				var data = socket.Receive(receiveCancellationToken);
+				
+				LogMessageType(logger, data);
+				
+				if (data.Length > 0) {
+					MessageRegistries.ToAgent.Handle(data, handler);
 				}
 			}
+		} catch (OperationCanceledException) {
+			// Ignore.
+		} finally {
+			logger.Verbose("ZeroMQ client stopped receiving messages.");
 
-			if (bytes.Length > 0) {
-				MessageRegistries.ToAgent.Handle(bytes, listener, cancellationToken);
-			}
+			disconnectSemaphore.Wait(CancellationToken.None);
+			keepAliveLoop.Cancel();
 		}
 	}
 
-	protected override async Task Disconnect(ClientSocket socket) {
-		var timeoutTask = Task.Delay(TimeSpan.FromSeconds(5));
-		var finishedTask = await Task.WhenAny(socket.SendMessage(new UnregisterAgentMessage(agentGuid)), timeoutTask);
-		if (finishedTask == timeoutTask) {
+	private static void LogMessageType(ILogger logger, ReadOnlyMemory<byte> data) {
+		if (!logger.IsEnabled(LogEventLevel.Verbose)) {
+			return;
+		}
+
+		if (data.Length > 0 && MessageRegistries.ToAgent.TryGetType(data, out var type)) {
+			logger.Verbose("Received {MessageType} ({Bytes} B) from server.", type.Name, data.Length);
+		}
+		else {
+			logger.Verbose("Received {Bytes} B message from server.", data.Length);
+		}
+	}
+
+	protected override async Task Disconnect() {
+		var unregisterTimeoutTask = Task.Delay(TimeSpan.FromSeconds(5), CancellationToken.None);
+		var finishedTask = await Task.WhenAny(ServerMessaging.Send(new UnregisterAgentMessage(agentGuid)), unregisterTimeoutTask);
+		if (finishedTask == unregisterTimeoutTask) {
 			config.Logger.Error("Timed out communicating agent shutdown with the server.");
 		}
 	}
+
+	private sealed class MessageToAgentHandler : MessageHandler<IMessageToAgentListener> {
+		public MessageToAgentHandler(IMessageToAgentListener listener, ILogger logger, TaskManager taskManager, CancellationToken cancellationToken) : base(listener, logger, taskManager, cancellationToken) {}
+		
+		protected override Task SendReply(uint sequenceId, byte[] serializedReply) {
+			return ServerMessaging.Send(new ReplyMessage(sequenceId, serializedReply));
+		}
+	}
 }

Agent/Phantom.Agent.Rpc/RpcServerConnection.cs

@@ -0,0 +1,46 @@
+using NetMQ;
+using NetMQ.Sockets;
+using Phantom.Common.Messages;
+using Phantom.Common.Messages.ToServer;
+using Phantom.Utils.Rpc.Message;
+
+namespace Phantom.Agent.Rpc; 
+
+public sealed class RpcServerConnection {
+	private readonly ClientSocket socket;
+	private readonly MessageReplyTracker replyTracker;
+
+	internal RpcServerConnection(ClientSocket socket, MessageReplyTracker replyTracker) {
+		this.socket = socket;
+		this.replyTracker = replyTracker;
+	}
+
+	private byte[] WriteBytes<TMessage, TReply>(TMessage message) where TMessage : IMessageToServer<TReply> {
+		return MessageRegistries.ToServer.Write<TMessage, TReply>(message).ToArray();
+	}
+
+	internal async Task Send<TMessage>(TMessage message) where TMessage : IMessageToServer {
+		var bytes = WriteBytes<TMessage, NoReply>(message);
+		if (bytes.Length > 0) {
+			await socket.SendAsync(bytes);
+		}
+	}
+
+	internal async Task<TReply?> Send<TMessage, TReply>(Func<uint, TMessage> messageFactory, TimeSpan waitForReplyTime, CancellationToken cancellationToken) where TMessage : IMessageToServer<TReply> where TReply : class {
+		var sequenceId = replyTracker.RegisterReply();
+		var message = messageFactory(sequenceId);
+		
+		var bytes = WriteBytes<TMessage, TReply>(message);
+		if (bytes.Length == 0) {
+			replyTracker.ForgetReply(sequenceId);
+			return null;
+		}
+
+		await socket.SendAsync(bytes);
+		return await replyTracker.WaitForReply<TReply>(message.SequenceId, waitForReplyTime, cancellationToken);
+	}
+
+	public void Receive(ReplyMessage message) {
+		replyTracker.ReceiveReply(message.SequenceId, message.SerializedReply);
+	}
+}

Agent/Phantom.Agent.Rpc/ServerMessaging.cs

@@ -1,7 +1,5 @@
-using NetMQ.Sockets;
-using Phantom.Common.Logging;
+using Phantom.Common.Logging;
 using Phantom.Common.Messages;
-using Phantom.Common.Messages.ToServer;
 using Serilog;
 
 namespace Phantom.Agent.Rpc;
@@ -9,47 +7,28 @@ namespace Phantom.Agent.Rpc;
 public static class ServerMessaging {
 	private static readonly ILogger Logger = PhantomLogger.Create(typeof(ServerMessaging));
 	
-	private static readonly TimeSpan KeepAliveInterval = TimeSpan.FromSeconds(10);
+	private static RpcServerConnection? CurrentConnection { get; set; }
+	private static RpcServerConnection CurrentConnectionOrThrow => CurrentConnection ?? throw new InvalidOperationException("Server connection not ready.");
+	
+	private static readonly object SetCurrentConnectionLock = new ();
 
-	private static ClientSocket? CurrentSocket { get; set; }
-	private static readonly object SetCurrentSocketLock = new ();
-
-	internal static void SetCurrentSocket(ClientSocket socket, CancellationToken cancellationToken) {
-		Logger.Information("Server socket ready.");
+	internal static void SetCurrentConnection(RpcServerConnection connection) {
+		lock (SetCurrentConnectionLock) {
+			if (CurrentConnection != null) {
+				throw new InvalidOperationException("Server connection can only be set once.");
+			}
+			
+			CurrentConnection = connection;
+		}
 		
-		bool isFirstSet = false;
-		lock (SetCurrentSocketLock) {
-			if (CurrentSocket == null) {
-				isFirstSet = true;
-			}
-
-			CurrentSocket = socket;
-		}
-
-		if (isFirstSet) {
-			Task.Factory.StartNew(static o => SendKeepAliveLoop((CancellationToken) o!), cancellationToken, cancellationToken, TaskCreationOptions.LongRunning, TaskScheduler.Default);
-		}
+		Logger.Information("Server connection ready.");
 	}
 
-	public static async Task SendMessage<TMessage>(TMessage message) where TMessage : IMessageToServer {
-		var currentSocket = CurrentSocket ?? throw new InvalidOperationException("Server socket not ready.");
-		await currentSocket.SendMessage(message);
+	public static Task Send<TMessage>(TMessage message) where TMessage : IMessageToServer {
+		return CurrentConnectionOrThrow.Send(message);
 	}
 
-	private static async Task SendKeepAliveLoop(CancellationToken cancellationToken) {
-		try {
-			while (true) {
-				await Task.Delay(KeepAliveInterval, cancellationToken);
-
-				var currentSocket = CurrentSocket;
-				if (currentSocket != null) {
-					await currentSocket.SendMessage(new AgentIsAliveMessage());
-				}
-			}
-		} catch (OperationCanceledException) {
-			// Ignore.
-		} finally {
-			Logger.Information("Stopped keep-alive loop.");
-		}
+	public static Task<TReply?> Send<TMessage, TReply>(Func<uint, TMessage> messageFactory, TimeSpan waitForReplyTime, CancellationToken cancellationToken) where TMessage : IMessageToServer<TReply> where TReply : class {
+		return CurrentConnectionOrThrow.Send<TMessage, TReply>(messageFactory, waitForReplyTime, cancellationToken);
 	}
 }

Agent/Phantom.Agent.Services/AgentServices.cs

@@ -1,19 +1,26 @@
 using Phantom.Agent.Minecraft.Java;
 using Phantom.Agent.Services.Instances;
 using Phantom.Common.Data.Agent;
+using Phantom.Common.Logging;
+using Phantom.Utils.Runtime;
+using Serilog;
 
 namespace Phantom.Agent.Services;
 
 public sealed class AgentServices {
-	private AgentFolders AgentFolders { get; }
+	private static readonly ILogger Logger = PhantomLogger.Create<AgentServices>();
 	
+	private AgentFolders AgentFolders { get; }
+	private TaskManager TaskManager { get; }
+
 	internal JavaRuntimeRepository JavaRuntimeRepository { get; }
 	internal InstanceSessionManager InstanceSessionManager { get; }
 
 	public AgentServices(AgentInfo agentInfo, AgentFolders agentFolders) {
 		this.AgentFolders = agentFolders;
+		this.TaskManager = new TaskManager();
 		this.JavaRuntimeRepository = new JavaRuntimeRepository();
-		this.InstanceSessionManager = new InstanceSessionManager(agentInfo, agentFolders, JavaRuntimeRepository);
+		this.InstanceSessionManager = new InstanceSessionManager(agentInfo, agentFolders, JavaRuntimeRepository, TaskManager);
 	}
 
 	public async Task Initialize() {
@@ -23,6 +30,12 @@ public sealed class AgentServices {
 	}
 
 	public async Task Shutdown() {
+		Logger.Information("Stopping instances...");
 		await InstanceSessionManager.StopAll();
+		
+		Logger.Information("Stopping task manager...");
+		await TaskManager.Stop();
+		
+		Logger.Information("Services stopped.");
 	}
 }

Agent/Phantom.Agent.Services/Instances/Instance.cs

@@ -2,6 +2,7 @@
 using Phantom.Agent.Rpc;
 using Phantom.Agent.Services.Instances.States;
 using Phantom.Common.Data.Instance;
+using Phantom.Common.Data.Minecraft;
 using Phantom.Common.Data.Replies;
 using Phantom.Common.Logging;
 using Phantom.Common.Messages.ToServer;
@@ -32,7 +33,7 @@ sealed class Instance : IDisposable {
 	private readonly LaunchServices launchServices;
 	private readonly PortManager portManager;
 
-	private InstanceStatus currentStatus;
+	private IInstanceStatus currentStatus;
 	private IInstanceState currentState;
 	private readonly SemaphoreSlim stateTransitioningActionSemaphore = new (1, 1);
 
@@ -46,24 +47,31 @@ sealed class Instance : IDisposable {
 		this.launchServices = launchServices;
 		this.portManager = portManager;
 		this.currentState = new InstanceNotRunningState();
-		this.currentStatus = InstanceStatus.IsNotRunning;
+		this.currentStatus = InstanceStatus.NotRunning;
 	}
 
 	private async Task ReportLastStatus() {
-		await ServerMessaging.SendMessage(new ReportInstanceStatusMessage(Configuration.InstanceGuid, currentStatus));
+		await ServerMessaging.Send(new ReportInstanceStatusMessage(Configuration.InstanceGuid, currentStatus));
 	}
 	
-	private bool TransitionState(IInstanceState newState) {
+	private void TransitionState(IInstanceState newState) {
 		if (currentState == newState) {
-			return false;
+			return;
 		}
 
 		if (currentState is IDisposable disposable) {
 			disposable.Dispose();
 		}
 
+		logger.Verbose("Transitioning instance state to: {NewState}", newState.GetType().Name);
+		
 		currentState = newState;
-		return true;
+		currentState.Initialize();
+	}
+
+	private T TransitionStateAndReturn<T>((IInstanceState State, T Result) newStateAndResult) {
+		TransitionState(newStateAndResult.State);
+		return newStateAndResult.Result;
 	}
 
 	public async Task Reconfigure(InstanceConfiguration configuration, BaseLauncher launcher, CancellationToken cancellationToken) {
@@ -80,41 +88,29 @@ sealed class Instance : IDisposable {
 	public async Task<LaunchInstanceResult> Launch(CancellationToken cancellationToken) {
 		await stateTransitioningActionSemaphore.WaitAsync(cancellationToken);
 		try {
-			if (TransitionState(currentState.Launch(new InstanceContextImpl(this)))) {
-				return LaunchInstanceResult.LaunchInitiated;
-			}
-
-			return currentState switch {
-				InstanceLaunchingState => LaunchInstanceResult.InstanceAlreadyLaunching,
-				InstanceRunningState   => LaunchInstanceResult.InstanceAlreadyRunning,
-				InstanceStoppingState  => LaunchInstanceResult.InstanceIsStopping,
-				_                      => LaunchInstanceResult.UnknownError
-			};
+			return TransitionStateAndReturn(currentState.Launch(new InstanceContextImpl(this)));
+		} catch (Exception e) {
+			logger.Error(e, "Caught exception while launching instance.");
+			return LaunchInstanceResult.UnknownError;
 		} finally {
 			stateTransitioningActionSemaphore.Release();
 		}
 	}
 
-	public async Task<StopInstanceResult> Stop() {
+	public async Task<StopInstanceResult> Stop(MinecraftStopStrategy stopStrategy) {
 		await stateTransitioningActionSemaphore.WaitAsync();
 		try {
-			if (TransitionState(currentState.Stop())) {
-				return StopInstanceResult.StopInitiated;
-			}
-
-			return currentState switch {
-				InstanceNotRunningState => StopInstanceResult.InstanceAlreadyStopped,
-				InstanceLaunchingState  => StopInstanceResult.StopInitiated,
-				InstanceStoppingState   => StopInstanceResult.InstanceAlreadyStopping,
-				_                       => StopInstanceResult.UnknownError
-			};
+			return TransitionStateAndReturn(currentState.Stop(stopStrategy));
+		} catch (Exception e) {
+			logger.Error(e, "Caught exception while stopping instance.");
+			return StopInstanceResult.UnknownError;
 		} finally {
 			stateTransitioningActionSemaphore.Release();
 		}
 	}
 
 	public async Task StopAndWait(TimeSpan waitTime) {
-		await Stop();
+		await Stop(MinecraftStopStrategy.Instant);
 
 		using var waitTokenSource = new CancellationTokenSource(waitTime);
 		var waitToken = waitTokenSource.Token;
@@ -141,13 +137,13 @@ sealed class Instance : IDisposable {
 		public override ILogger Logger => instance.logger;
 		public override string ShortName => instance.shortName;
 
-		public override void ReportStatus(InstanceStatus newStatus) {
+		public override void ReportStatus(IInstanceStatus newStatus) {
 			int myStatusUpdateCounter = Interlocked.Increment(ref statusUpdateCounter);
 			
-			Task.Run(async () => {
+			instance.launchServices.TaskManager.Run(async () => {
 				if (myStatusUpdateCounter == statusUpdateCounter) {
 					instance.currentStatus = newStatus;
-					await ServerMessaging.SendMessage(new ReportInstanceStatusMessage(Configuration.InstanceGuid, newStatus));
+					await ServerMessaging.Send(new ReportInstanceStatusMessage(Configuration.InstanceGuid, newStatus));
 				}
 			});
 		}
@@ -156,6 +152,8 @@ sealed class Instance : IDisposable {
 			instance.stateTransitioningActionSemaphore.Wait();
 			try {
 				instance.TransitionState(newState());
+			} catch (Exception e) {
+				instance.logger.Error(e, "Caught exception during state transition.");
 			} finally {
 				instance.stateTransitioningActionSemaphore.Release();
 			}

Agent/Phantom.Agent.Services/Instances/InstanceContext.cs

@@ -19,7 +19,7 @@ abstract class InstanceContext {
 		Launcher = launcher;
 	}
 
-	public abstract void ReportStatus(InstanceStatus newStatus);
+	public abstract void ReportStatus(IInstanceStatus newStatus);
 	public abstract void TransitionState(Func<IInstanceState> newState);
 
 	public void TransitionState(IInstanceState newState) {

Agent/Phantom.Agent.Services/Instances/InstanceLogSender.cs

@@ -0,0 +1,96 @@
+using System.Collections.Immutable;
+using Phantom.Agent.Rpc;
+using Phantom.Common.Logging;
+using Phantom.Common.Messages.ToServer;
+using Phantom.Utils.Collections;
+using Phantom.Utils.Runtime;
+using Serilog;
+
+namespace Phantom.Agent.Services.Instances;
+
+sealed class InstanceLogSender {
+	private static readonly TimeSpan SendDelay = TimeSpan.FromMilliseconds(200);
+
+	private readonly Guid instanceGuid;
+	private readonly ILogger logger;
+	private readonly CancellationTokenSource cancellationTokenSource;
+	private readonly CancellationToken cancellationToken;
+
+	private readonly SemaphoreSlim semaphore = new (1, 1);
+	private readonly RingBuffer<string> buffer = new (1000);
+
+	public InstanceLogSender(TaskManager taskManager, Guid instanceGuid, string name) {
+		this.instanceGuid = instanceGuid;
+		this.logger = PhantomLogger.Create<InstanceLogSender>(name);
+		this.cancellationTokenSource = new CancellationTokenSource();
+		this.cancellationToken = cancellationTokenSource.Token;
+		taskManager.Run(Run);
+	}
+
+	private async Task Run() {
+		logger.Verbose("Task started.");
+
+		try {
+			try {
+				while (!cancellationToken.IsCancellationRequested) {
+					await SendOutputToServer(await DequeueOrThrow());
+					await Task.Delay(SendDelay, cancellationToken);
+				}
+			} catch (OperationCanceledException) {
+				// Ignore.
+			}
+
+			// Flush remaining lines.
+			await SendOutputToServer(DequeueWithoutSemaphore());
+		} catch (Exception e) {
+			logger.Error(e, "Caught exception in task.");
+		} finally {
+			cancellationTokenSource.Dispose();
+			logger.Verbose("Task stopped.");
+		}
+	}
+
+	private async Task SendOutputToServer(ImmutableArray<string> lines) {
+		if (!lines.IsEmpty) {
+			await ServerMessaging.Send(new InstanceOutputMessage(instanceGuid, lines));
+		}
+	}
+
+	private ImmutableArray<string> DequeueWithoutSemaphore() {
+		ImmutableArray<string> lines = buffer.Count > 0 ? buffer.EnumerateLast(uint.MaxValue).ToImmutableArray() : ImmutableArray<string>.Empty;
+		buffer.Clear();
+		return lines;
+	}
+
+	private async Task<ImmutableArray<string>> DequeueOrThrow() {
+		await semaphore.WaitAsync(cancellationToken);
+
+		try {
+			return DequeueWithoutSemaphore();
+		} finally {
+			semaphore.Release();
+		}
+	}
+
+	public void Enqueue(string line) {
+		try {
+			semaphore.Wait(cancellationToken);
+		} catch (Exception) {
+			return;
+		}
+
+		try {
+			buffer.Add(line);
+		} finally {
+			semaphore.Release();
+		}
+	}
+
+	public void Cancel() {
+		try {
+			cancellationTokenSource.Cancel();
+		} catch (ObjectDisposedException) {
+			// Ignore.
+		}
+	}
+}

Agent/Phantom.Agent.Services/Instances/InstanceLogSenderThread.cs

@@ -1,84 +0,0 @@
-using System.Collections.Immutable;
-using System.Diagnostics.CodeAnalysis;
-using Phantom.Agent.Rpc;
-using Phantom.Common.Logging;
-using Phantom.Common.Messages.ToServer;
-using Phantom.Utils.Collections;
-using Serilog;
-
-namespace Phantom.Agent.Services.Instances; 
-
-sealed class InstanceLogSenderThread {
-	private readonly Guid instanceGuid;
-	private readonly ILogger logger;
-	private readonly CancellationTokenSource cancellationTokenSource;
-	private readonly CancellationToken cancellationToken;
-	
-	private readonly SemaphoreSlim semaphore = new (1, 1);
-	private readonly RingBuffer<string> buffer = new (1000);
-	
-	public InstanceLogSenderThread(Guid instanceGuid, string name) {
-		this.instanceGuid = instanceGuid;
-		this.logger = PhantomLogger.Create<InstanceLogSenderThread>(name);
-		this.cancellationTokenSource = new CancellationTokenSource();
-		this.cancellationToken = cancellationTokenSource.Token;
-		
-		var thread = new Thread(Run) {
-			IsBackground = true,
-			Name = "Instance Log Sender (" + name + ")"
-		};
-		
-		thread.Start();
-	}
-
-	[SuppressMessage("ReSharper", "LocalVariableHidesMember")]
-	private async void Run() {
-		logger.Verbose("Thread started.");
-		
-		try {
-			while (!cancellationToken.IsCancellationRequested) {
-				await semaphore.WaitAsync(cancellationToken);
-
-				ImmutableArray<string> lines;
-				
-				try {
-					lines = buffer.Count > 0 ? buffer.EnumerateLast(uint.MaxValue).ToImmutableArray() : ImmutableArray<string>.Empty;
-					buffer.Clear();
-				} finally {
-					semaphore.Release();
-				}
-
-				if (lines.Length > 0) {
-					await ServerMessaging.SendMessage(new InstanceOutputMessage(instanceGuid, lines));
-				}
-
-				await Task.Delay(TimeSpan.FromMilliseconds(200), cancellationToken);
-			}
-		} catch (OperationCanceledException) {
-			// Ignore.
-		} catch (Exception e) {
-			logger.Error(e, "Caught exception in thread.");
-		} finally {
-			cancellationTokenSource.Dispose();
-			logger.Verbose("Thread stopped.");
-		}
-	}
-
-	public void Enqueue(string line) {
-		try {
-			semaphore.Wait(cancellationToken);
-		} catch (Exception) {
-			return;
-		}
-
-		try {
-			buffer.Add(line);
-		} finally {
-			semaphore.Release();
-		}
-	}
-
-	public void Cancel() {
-		cancellationTokenSource.Cancel();
-	}
-}

Agent/Phantom.Agent.Services/Instances/InstanceSessionManager.cs

@@ -1,4 +1,5 @@
-using Phantom.Agent.Minecraft.Instance;
+using System.Diagnostics.CodeAnalysis;
+using Phantom.Agent.Minecraft.Instance;
 using Phantom.Agent.Minecraft.Java;
 using Phantom.Agent.Minecraft.Launcher;
 using Phantom.Agent.Minecraft.Launcher.Types;
@@ -7,8 +8,11 @@ using Phantom.Agent.Minecraft.Server;
 using Phantom.Common.Data;
 using Phantom.Common.Data.Agent;
 using Phantom.Common.Data.Instance;
+using Phantom.Common.Data.Minecraft;
 using Phantom.Common.Data.Replies;
 using Phantom.Common.Logging;
+using Phantom.Utils.IO;
+using Phantom.Utils.Runtime;
 using Serilog;
 
 namespace Phantom.Agent.Services.Instances;
@@ -19,6 +23,7 @@ sealed class InstanceSessionManager : IDisposable {
 	private readonly AgentInfo agentInfo;
 	private readonly string basePath;
 
+	private readonly MinecraftServerExecutables minecraftServerExecutables;
 	private readonly LaunchServices launchServices;
 	private readonly PortManager portManager;
 	private readonly Dictionary<Guid, Instance> instances = new ();
@@ -27,19 +32,40 @@ sealed class InstanceSessionManager : IDisposable {
 	private readonly CancellationToken shutdownCancellationToken;
 	private readonly SemaphoreSlim semaphore = new (1, 1);
 
-	public InstanceSessionManager(AgentInfo agentInfo, AgentFolders agentFolders, JavaRuntimeRepository javaRuntimeRepository) {
+	public InstanceSessionManager(AgentInfo agentInfo, AgentFolders agentFolders, JavaRuntimeRepository javaRuntimeRepository, TaskManager taskManager) {
 		this.agentInfo = agentInfo;
 		this.basePath = agentFolders.InstancesFolderPath;
-		this.launchServices = new LaunchServices(new MinecraftServerExecutables(agentFolders.ServerExecutableFolderPath), javaRuntimeRepository);
+		this.minecraftServerExecutables = new MinecraftServerExecutables(agentFolders.ServerExecutableFolderPath);
+		this.launchServices = new LaunchServices(taskManager, minecraftServerExecutables, javaRuntimeRepository);
 		this.portManager = new PortManager(agentInfo.AllowedServerPorts, agentInfo.AllowedRconPorts);
 		this.shutdownCancellationToken = shutdownCancellationTokenSource.Token;
 	}
 
-	public async Task<ConfigureInstanceResult> Configure(InstanceConfiguration configuration) {
+	[SuppressMessage("ReSharper", "ConvertIfStatementToReturnStatement")]
+	private async Task<InstanceActionResult<T>> AcquireSemaphoreAndRunWithInstance<T>(Guid instanceGuid, Func<Instance, Task<T>> func) {
 		try {
 			await semaphore.WaitAsync(shutdownCancellationToken);
 		} catch (OperationCanceledException) {
-			return ConfigureInstanceResult.AgentShuttingDown;
+			return InstanceActionResult.General<T>(InstanceActionGeneralResult.AgentShuttingDown);
+		}
+
+		try {
+			if (!instances.TryGetValue(instanceGuid, out var instance)) {
+				return InstanceActionResult.General<T>(InstanceActionGeneralResult.InstanceDoesNotExist);
+			}
+			else {
+				return InstanceActionResult.Concrete(await func(instance));
+			}
+		} finally {
+			semaphore.Release();
+		}
+	}
+	
+	public async Task<InstanceActionResult<ConfigureInstanceResult>> Configure(InstanceConfiguration configuration) {
+		try {
+			await semaphore.WaitAsync(shutdownCancellationToken);
+		} catch (OperationCanceledException) {
+			return InstanceActionResult.General<ConfigureInstanceResult>(InstanceActionGeneralResult.AgentShuttingDown);
 		}
 
 		var instanceGuid = configuration.InstanceGuid;
@@ -47,12 +73,12 @@ sealed class InstanceSessionManager : IDisposable {
 		try {
 			var otherInstances = instances.Values.Where(inst => inst.Configuration.InstanceGuid != instanceGuid).ToArray();
 			if (otherInstances.Length + 1 > agentInfo.MaxInstances) {
-				return ConfigureInstanceResult.InstanceLimitExceeded;
+				return InstanceActionResult.Concrete(ConfigureInstanceResult.InstanceLimitExceeded);
 			}
 
 			var availableMemory = agentInfo.MaxMemory - otherInstances.Aggregate(RamAllocationUnits.Zero, static (total, instance) => total + instance.Configuration.MemoryAllocation);
 			if (availableMemory < configuration.MemoryAllocation) {
-				return ConfigureInstanceResult.MemoryLimitExceeded;
+				return InstanceActionResult.Concrete(ConfigureInstanceResult.MemoryLimitExceeded);
 			}
 
 			var heapMegabytes = configuration.MemoryAllocation.InMegabytes;
@@ -62,11 +88,12 @@ sealed class InstanceSessionManager : IDisposable {
 			);
 
 			var instanceFolder = Path.Combine(basePath, instanceGuid.ToString());
-			Directory.CreateDirectory(instanceFolder);
+			Directories.Create(instanceFolder, Chmod.URWX_GRX);
 
 			var properties = new InstanceProperties(
 				configuration.JavaRuntimeGuid,
 				jvmProperties,
+				configuration.JvmArguments,
 				instanceFolder,
 				configuration.MinecraftVersion,
 				new ServerProperties(configuration.ServerPort, configuration.RconPort)
@@ -87,70 +114,22 @@ sealed class InstanceSessionManager : IDisposable {
 				await instance.Launch(shutdownCancellationToken);
 			}
 
-			return ConfigureInstanceResult.Success;
+			return InstanceActionResult.Concrete(ConfigureInstanceResult.Success);
 		} finally {
 			semaphore.Release();
 		}
 	}
 
-	public async Task<LaunchInstanceResult> Launch(Guid instanceGuid) {
-		try {
-			await semaphore.WaitAsync(shutdownCancellationToken);
-		} catch (OperationCanceledException) {
-			return LaunchInstanceResult.AgentShuttingDown;
-		}
-
-		try {
-			if (!instances.TryGetValue(instanceGuid, out var instance)) {
-				return LaunchInstanceResult.InstanceDoesNotExist;
-			}
-			else {
-				return await instance.Launch(shutdownCancellationToken);
-			}
-		} finally {
-			semaphore.Release();
-		}
+	public Task<InstanceActionResult<LaunchInstanceResult>> Launch(Guid instanceGuid) {
+		return AcquireSemaphoreAndRunWithInstance(instanceGuid, instance => instance.Launch(shutdownCancellationToken));
 	}
 
-	public async Task<StopInstanceResult> Stop(Guid instanceGuid) {
-		try {
-			await semaphore.WaitAsync(shutdownCancellationToken);
-		} catch (OperationCanceledException) {
-			return StopInstanceResult.AgentShuttingDown;
-		}
-
-		try {
-			if (!instances.TryGetValue(instanceGuid, out var instance)) {
-				return StopInstanceResult.InstanceDoesNotExist;
-			}
-			else {
-				return await instance.Stop();
-			}
-		} finally {
-			semaphore.Release();
-		}
+	public Task<InstanceActionResult<StopInstanceResult>> Stop(Guid instanceGuid, MinecraftStopStrategy stopStrategy) {
+		return AcquireSemaphoreAndRunWithInstance(instanceGuid, instance => instance.Stop(stopStrategy));
 	}
 
-	public async Task<SendCommandToInstanceResult> SendCommand(Guid instanceGuid, string command) {
-		try {
-			await semaphore.WaitAsync(shutdownCancellationToken);
-		} catch (OperationCanceledException) {
-			return SendCommandToInstanceResult.AgentShuttingDown;
-		}
-
-		try {
-			if (!instances.TryGetValue(instanceGuid, out var instance)) {
-				return SendCommandToInstanceResult.InstanceDoesNotExist;
-			}
-
-			if (!await instance.SendCommand(command, shutdownCancellationToken)) {
-				return SendCommandToInstanceResult.UnknownError;
-			}
-
-			return SendCommandToInstanceResult.Success;
-		} finally {
-			semaphore.Release();
-		}
+	public Task<InstanceActionResult<SendCommandToInstanceResult>> SendCommand(Guid instanceGuid, string command) {
+		return AcquireSemaphoreAndRunWithInstance(instanceGuid, async instance => await instance.SendCommand(command, shutdownCancellationToken) ? SendCommandToInstanceResult.Success : SendCommandToInstanceResult.UnknownError);
 	}
 
 	public async Task StopAll() {
@@ -166,6 +145,7 @@ sealed class InstanceSessionManager : IDisposable {
 	}
 
 	public void Dispose() {
+		minecraftServerExecutables.Dispose();
 		shutdownCancellationTokenSource.Dispose();
 		semaphore.Dispose();
 	}

Agent/Phantom.Agent.Services/Instances/PortManager.cs

@@ -14,17 +14,28 @@ sealed class PortManager {
 	}
 
 	public Result Reserve(InstanceConfiguration configuration) {
+		var serverPort = configuration.ServerPort;
+		var rconPort = configuration.RconPort;
+		
+		if (!allowedServerPorts.Contains(serverPort)) {
+			return Result.ServerPortNotAllowed;
+		}
+
+		if (!allowedRconPorts.Contains(rconPort)) {
+			return Result.RconPortNotAllowed;
+		}
+		
 		lock (usedPorts) {
-			if (usedPorts.Contains(configuration.ServerPort)) {
+			if (usedPorts.Contains(serverPort)) {
 				return Result.ServerPortAlreadyInUse;
 			}
 
-			if (usedPorts.Contains(configuration.RconPort)) {
+			if (usedPorts.Contains(rconPort)) {
 				return Result.RconPortAlreadyInUse;
 			}
 
-			usedPorts.Add(configuration.ServerPort);
-			usedPorts.Add(configuration.RconPort);
+			usedPorts.Add(serverPort);
+			usedPorts.Add(rconPort);
 		}
 
 		return Result.Success;
@@ -42,6 +53,6 @@ sealed class PortManager {
 		ServerPortNotAllowed,
 		ServerPortAlreadyInUse,
 		RconPortNotAllowed,
-		RconPortAlreadyInUse,
+		RconPortAlreadyInUse
 	}
 }

Agent/Phantom.Agent.Services/Instances/States/IInstanceState.cs

@@ -1,7 +1,11 @@
-namespace Phantom.Agent.Services.Instances.States; 
+using Phantom.Common.Data.Minecraft;
+using Phantom.Common.Data.Replies;
+
+namespace Phantom.Agent.Services.Instances.States; 
 
 interface IInstanceState {
-	IInstanceState Launch(InstanceContext context);
-	IInstanceState Stop();
+	void Initialize();
+	(IInstanceState, LaunchInstanceResult) Launch(InstanceContext context);
+	(IInstanceState, StopInstanceResult) Stop(MinecraftStopStrategy stopStrategy);
 	Task<bool> SendCommand(string command, CancellationToken cancellationToken);
 }

Agent/Phantom.Agent.Services/Instances/States/InstanceLaunchingState.cs

@@ -2,6 +2,8 @@
 using Phantom.Agent.Minecraft.Launcher;
 using Phantom.Agent.Minecraft.Server;
 using Phantom.Common.Data.Instance;
+using Phantom.Common.Data.Minecraft;
+using Phantom.Common.Data.Replies;
 
 namespace Phantom.Agent.Services.Instances.States;
 
@@ -12,10 +14,12 @@ sealed class InstanceLaunchingState : IInstanceState, IDisposable {
 
 	public InstanceLaunchingState(InstanceContext context) {
 		this.context = context;
-		this.context.Logger.Information("Session starting...");
-		this.context.ReportStatus(InstanceStatus.IsLaunching);
-		
-		var launchTask = Task.Run(DoLaunch);
+	}
+
+	public void Initialize() {
+		context.Logger.Information("Session starting...");
+
+		var launchTask = context.LaunchServices.TaskManager.Run(DoLaunch);
 		launchTask.ContinueWith(OnLaunchSuccess, CancellationToken.None, TaskContinuationOptions.OnlyOnRanToCompletion, TaskScheduler.Default);
 		launchTask.ContinueWith(OnLaunchFailure, CancellationToken.None, TaskContinuationOptions.NotOnRanToCompletion, TaskScheduler.Default);
 	}
@@ -23,29 +27,38 @@ sealed class InstanceLaunchingState : IInstanceState, IDisposable {
 	private async Task<InstanceSession> DoLaunch() {
 		var cancellationToken = cancellationTokenSource.Token;
 		cancellationToken.ThrowIfCancellationRequested();
-		
+
 		void OnDownloadProgress(object? sender, DownloadProgressEventArgs args) {
 			byte progress = (byte) Math.Min(args.DownloadedBytes * 100 / args.TotalBytes, 100);
-			
+
 			if (lastDownloadProgress != progress) {
 				lastDownloadProgress = progress;
-				context.ReportStatus(new InstanceStatus.Downloading(progress));
+				context.ReportStatus(InstanceStatus.Downloading(progress));
 			}
 		}
 
-		var launchResult = await context.Launcher.Launch(context.LaunchServices, OnDownloadProgress, cancellationToken);
-		if (launchResult is LaunchResult.CouldNotDownloadMinecraftServer) {
+		var launchResult = await context.Launcher.Launch(context.Logger, context.LaunchServices, OnDownloadProgress, cancellationToken);
+		if (launchResult is LaunchResult.InvalidJavaRuntime) {
+			throw new LaunchFailureException(InstanceLaunchFailReason.JavaRuntimeNotFound, "Session failed to launch, invalid Java runtime.");
+		}
+		else if (launchResult is LaunchResult.InvalidJvmArguments) {
+			throw new LaunchFailureException(InstanceLaunchFailReason.InvalidJvmArguments, "Session failed to launch, invalid JVM arguments.");
+		}
+		else if (launchResult is LaunchResult.CouldNotDownloadMinecraftServer) {
 			throw new LaunchFailureException(InstanceLaunchFailReason.CouldNotDownloadMinecraftServer, "Session failed to launch, could not download Minecraft server.");
 		}
-		else if (launchResult is LaunchResult.InvalidJavaRuntime) {
-			throw new LaunchFailureException(InstanceLaunchFailReason.JavaRuntimeNotFound, "Session failed to launch, invalid Java runtime.");
+		else if (launchResult is LaunchResult.CouldNotConfigureMinecraftServer) {
+			throw new LaunchFailureException(InstanceLaunchFailReason.CouldNotConfigureMinecraftServer, "Session failed to launch, could not configure Minecraft server.");
+		}
+		else if (launchResult is LaunchResult.CouldNotStartMinecraftServer) {
+			throw new LaunchFailureException(InstanceLaunchFailReason.CouldNotStartMinecraftServer, "Session failed to launch, could not start Minecraft server.");
 		}
 
 		if (launchResult is not LaunchResult.Success launchSuccess) {
 			throw new LaunchFailureException(InstanceLaunchFailReason.UnknownError, "Session failed to launch.");
 		}
 
-		context.ReportStatus(InstanceStatus.IsLaunching);
+		context.ReportStatus(InstanceStatus.Launching);
 		return launchSuccess.Session;
 	}
 
@@ -53,7 +66,7 @@ sealed class InstanceLaunchingState : IInstanceState, IDisposable {
 		context.TransitionState(() => {
 			if (cancellationTokenSource.IsCancellationRequested) {
 				context.PortManager.Release(context.Configuration);
-				context.ReportStatus(InstanceStatus.IsNotRunning);
+				context.ReportStatus(InstanceStatus.NotRunning);
 				return new InstanceNotRunningState();
 			}
 			else {
@@ -65,12 +78,12 @@ sealed class InstanceLaunchingState : IInstanceState, IDisposable {
 	private void OnLaunchFailure(Task task) {
 		if (task.Exception is { InnerException: LaunchFailureException e }) {
 			context.Logger.Error(e.LogMessage);
-			context.ReportStatus(new InstanceStatus.Failed(e.Reason));
+			context.ReportStatus(InstanceStatus.Failed(e.Reason));
 		}
 		else {
-			context.ReportStatus(new InstanceStatus.Failed(InstanceLaunchFailReason.UnknownError));
+			context.ReportStatus(InstanceStatus.Failed(InstanceLaunchFailReason.UnknownError));
 		}
-		
+
 		context.PortManager.Release(context.Configuration);
 		context.TransitionState(new InstanceNotRunningState());
 	}
@@ -78,20 +91,20 @@ sealed class InstanceLaunchingState : IInstanceState, IDisposable {
 	private sealed class LaunchFailureException : Exception {
 		public InstanceLaunchFailReason Reason { get; }
 		public string LogMessage { get; }
-		
+
 		public LaunchFailureException(InstanceLaunchFailReason reason, string logMessage) {
 			this.Reason = reason;
 			this.LogMessage = logMessage;
 		}
 	}
 
-	public IInstanceState Launch(InstanceContext context) {
-		return this;
+	public (IInstanceState, LaunchInstanceResult) Launch(InstanceContext context) {
+		return (this, LaunchInstanceResult.InstanceAlreadyLaunching);
 	}
 
-	public IInstanceState Stop() {
+	public (IInstanceState, StopInstanceResult) Stop(MinecraftStopStrategy stopStrategy) {
 		cancellationTokenSource.Cancel();
-		return this;
+		return (this, StopInstanceResult.StopInitiated);
 	}
 
 	public Task<bool> SendCommand(string command, CancellationToken cancellationToken) {

Agent/Phantom.Agent.Services/Instances/States/InstanceNotRunningState.cs

@@ -1,9 +1,13 @@
 using Phantom.Common.Data.Instance;
+using Phantom.Common.Data.Minecraft;
+using Phantom.Common.Data.Replies;
 
 namespace Phantom.Agent.Services.Instances.States; 
 
 sealed class InstanceNotRunningState : IInstanceState {
-	public IInstanceState Launch(InstanceContext context) {
+	public void Initialize() {}
+
+	public (IInstanceState, LaunchInstanceResult) Launch(InstanceContext context) {
 		InstanceLaunchFailReason? failReason = context.PortManager.Reserve(context.Configuration) switch {
 			PortManager.Result.ServerPortNotAllowed   => InstanceLaunchFailReason.ServerPortNotAllowed,
 			PortManager.Result.ServerPortAlreadyInUse => InstanceLaunchFailReason.ServerPortAlreadyInUse,
@@ -13,15 +17,16 @@ sealed class InstanceNotRunningState : IInstanceState {
 		};
 
 		if (failReason != null) {
-			context.ReportStatus(new InstanceStatus.Failed(failReason.Value));
-			return this;
+			context.ReportStatus(InstanceStatus.Failed(failReason.Value));
+			return (this, LaunchInstanceResult.LaunchInitiated);
 		}
 		
-		return new InstanceLaunchingState(context);
+		context.ReportStatus(InstanceStatus.Launching);
+		return (new InstanceLaunchingState(context), LaunchInstanceResult.LaunchInitiated);
 	}
 
-	public IInstanceState Stop() {
-		return this;
+	public (IInstanceState, StopInstanceResult) Stop(MinecraftStopStrategy stopStrategy) {
+		return (this, StopInstanceResult.InstanceAlreadyStopped);
 	}
 
 	public Task<bool> SendCommand(string command, CancellationToken cancellationToken) {

Agent/Phantom.Agent.Services/Instances/States/InstanceRunningState.cs

@@ -1,58 +1,130 @@
-using Phantom.Agent.Minecraft.Instance;
+using Phantom.Agent.Minecraft.Command;
+using Phantom.Agent.Minecraft.Instance;
 using Phantom.Common.Data.Instance;
+using Phantom.Common.Data.Minecraft;
+using Phantom.Common.Data.Replies;
 
 namespace Phantom.Agent.Services.Instances.States;
 
 sealed class InstanceRunningState : IInstanceState {
 	private readonly InstanceContext context;
 	private readonly InstanceSession session;
-	private readonly InstanceLogSenderThread logSenderThread;
+	private readonly InstanceLogSender logSender;
 	private readonly SessionObjects sessionObjects;
+	
+	private readonly CancellationTokenSource delayedStopCancellationTokenSource = new ();
+	private bool stateOwnsDelayedStopCancellationTokenSource = true;
+	private bool isStopping;
 
 	public InstanceRunningState(InstanceContext context, InstanceSession session) {
 		this.context = context;
 		this.session = session;
-		this.logSenderThread = new InstanceLogSenderThread(context.Configuration.InstanceGuid, context.ShortName);
-		this.sessionObjects = new SessionObjects(context, session, logSenderThread);
-
-		this.session.AddOutputListener(SessionOutput);
-		this.session.SessionEnded += SessionEnded;
+		this.logSender = new InstanceLogSender(context.LaunchServices.TaskManager, context.Configuration.InstanceGuid, context.ShortName);
+		this.sessionObjects = new SessionObjects(this);
+	}
 
+	public void Initialize() {
+		session.AddOutputListener(SessionOutput);
+		session.SessionEnded += SessionEnded;
+		
 		if (session.HasEnded) {
 			if (sessionObjects.Dispose()) {
 				context.Logger.Warning("Session ended immediately after it was started.");
-				context.ReportStatus(new InstanceStatus.Failed(InstanceLaunchFailReason.UnknownError));
-				Task.Run(() => context.TransitionState(new InstanceNotRunningState()));
+				context.ReportStatus(InstanceStatus.Failed(InstanceLaunchFailReason.UnknownError));
+				context.LaunchServices.TaskManager.Run(() => context.TransitionState(new InstanceNotRunningState()));
 			}
 		}
 		else {
-			context.ReportStatus(InstanceStatus.IsRunning);
+			context.ReportStatus(InstanceStatus.Running);
 			context.Logger.Information("Session started.");
 		}
 	}
 
 	private void SessionOutput(object? sender, string e) {
 		context.Logger.Verbose("[Server] {Line}", e);
-		logSenderThread.Enqueue(e);
+		logSender.Enqueue(e);
 	}
 
 	private void SessionEnded(object? sender, EventArgs e) {
-		if (sessionObjects.Dispose()) {
+		if (!sessionObjects.Dispose()) {
+			return;
+		}
+
+		if (isStopping) {
 			context.Logger.Information("Session ended.");
-			context.ReportStatus(InstanceStatus.IsNotRunning);
+			context.ReportStatus(InstanceStatus.NotRunning);
 			context.TransitionState(new InstanceNotRunningState());
 		}
+		else {
+			context.Logger.Information("Session ended unexpectedly, restarting...");
+			context.ReportStatus(InstanceStatus.Restarting);
+			context.TransitionState(new InstanceLaunchingState(context));
+		}
 	}
 
-	public IInstanceState Launch(InstanceContext context) {
-		return this;
+	public (IInstanceState, LaunchInstanceResult) Launch(InstanceContext context) {
+		return (this, LaunchInstanceResult.InstanceAlreadyRunning);
 	}
 
-	public IInstanceState Stop() {
+	public (IInstanceState, StopInstanceResult) Stop(MinecraftStopStrategy stopStrategy) {
+		if (stopStrategy == MinecraftStopStrategy.Instant) {
+			CancelDelayedStop();
+			return (PrepareStoppedState(), StopInstanceResult.StopInitiated);
+		}
+
+		if (isStopping) {
+			// TODO change delay or something
+			return (this, StopInstanceResult.InstanceAlreadyStopping);
+		}
+		
+		isStopping = true;
+		context.LaunchServices.TaskManager.Run(() => StopLater(stopStrategy.Seconds));
+		return (this, StopInstanceResult.StopInitiated);
+	}
+
+	private IInstanceState PrepareStoppedState() {
 		session.SessionEnded -= SessionEnded;
 		return new InstanceStoppingState(context, session, sessionObjects);
 	}
 
+	private void CancelDelayedStop() {
+		try {
+			delayedStopCancellationTokenSource.Cancel();
+		} catch (ObjectDisposedException) {
+			// ignore
+		}
+	}
+
+	private async Task StopLater(int seconds) {
+		var cancellationToken = delayedStopCancellationTokenSource.Token;
+
+		try {
+			stateOwnsDelayedStopCancellationTokenSource = false;
+
+			int[] stops = { 60, 30, 10, 5, 4, 3, 2, 1, 0 };
+			
+			foreach (var stop in stops) {
+				if (seconds > stop) {
+					await SendCommand(MinecraftCommand.Say("Server shutting down in " + seconds + (seconds == 1 ? " second." : " seconds.")), cancellationToken);
+					await Task.Delay(TimeSpan.FromSeconds(seconds - stop), cancellationToken);
+					seconds = stop;
+				}
+			}
+		} catch (OperationCanceledException) {
+			context.Logger.Verbose("Cancelled delayed stop.");
+			return;
+		} catch (ObjectDisposedException) {
+			return;
+		} catch (Exception e) {
+			context.Logger.Warning(e, "Caught exception during delayed stop.");
+			return;
+		} finally {
+			delayedStopCancellationTokenSource.Dispose();
+		}
+
+		context.TransitionState(PrepareStoppedState());
+	}
+
 	public async Task<bool> SendCommand(string command, CancellationToken cancellationToken) {
 		try {
 			context.Logger.Information("Sending command: {Command}", command);
@@ -67,15 +139,11 @@ sealed class InstanceRunningState : IInstanceState {
 	}
 
 	public sealed class SessionObjects {
-		private readonly InstanceContext context;
-		private readonly InstanceSession session;
-		private readonly InstanceLogSenderThread logSenderThread;
+		private readonly InstanceRunningState state;
 		private bool isDisposed;
 
-		public SessionObjects(InstanceContext context, InstanceSession session, InstanceLogSenderThread logSenderThread) {
-			this.context = context;
-			this.session = session;
-			this.logSenderThread = logSenderThread;
+		public SessionObjects(InstanceRunningState state) {
+			this.state = state;
 		}
 
 		public bool Dispose() {
@@ -87,9 +155,16 @@ sealed class InstanceRunningState : IInstanceState {
 				isDisposed = true;
 			}
 
-			logSenderThread.Cancel();
-			session.Dispose();
-			context.PortManager.Release(context.Configuration);
+			if (state.stateOwnsDelayedStopCancellationTokenSource) {
+				state.delayedStopCancellationTokenSource.Dispose();
+			}
+			else {
+				state.CancelDelayedStop();
+			}
+			
+			state.logSender.Cancel();
+			state.session.Dispose();
+			state.context.PortManager.Release(state.context.Configuration);
 			return true;
 		}
 	}

Agent/Phantom.Agent.Services/Instances/States/InstanceStoppingState.cs

@@ -1,5 +1,8 @@
-using Phantom.Agent.Minecraft.Instance;
+using Phantom.Agent.Minecraft.Command;
+using Phantom.Agent.Minecraft.Instance;
 using Phantom.Common.Data.Instance;
+using Phantom.Common.Data.Minecraft;
+using Phantom.Common.Data.Replies;
 
 namespace Phantom.Agent.Services.Instances.States; 
 
@@ -12,10 +15,12 @@ sealed class InstanceStoppingState : IInstanceState, IDisposable {
 		this.sessionObjects = sessionObjects;
 		this.session = session;
 		this.context = context;
-		this.context.Logger.Information("Session stopping.");
-		this.context.ReportStatus(InstanceStatus.IsStopping);
-		
-		Task.Run(DoStop);
+	}
+
+	public void Initialize() {
+		context.Logger.Information("Session stopping.");
+		context.ReportStatus(InstanceStatus.Stopping);
+		context.LaunchServices.TaskManager.Run(DoStop);
 	}
 
 	private async Task DoStop() {
@@ -27,7 +32,7 @@ sealed class InstanceStoppingState : IInstanceState, IDisposable {
 			await DoWaitForSessionToEnd();
 		} finally {
 			context.Logger.Information("Session stopped.");
-			context.ReportStatus(InstanceStatus.IsNotRunning);
+			context.ReportStatus(InstanceStatus.NotRunning);
 			context.TransitionState(new InstanceNotRunningState());
 		}
 	}
@@ -35,7 +40,7 @@ sealed class InstanceStoppingState : IInstanceState, IDisposable {
 	private async Task DoSendStopCommand() {
 		using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(5));
 		try {
-			await session.SendCommand("stop", cts.Token);
+			await session.SendCommand(MinecraftCommand.Stop, cts.Token);
 		} catch (OperationCanceledException) {
 			// ignore
 		} catch (Exception e) {
@@ -57,12 +62,12 @@ sealed class InstanceStoppingState : IInstanceState, IDisposable {
 		}
 	}
 
-	public IInstanceState Launch(InstanceContext context) {
-		return this;
+	public (IInstanceState, LaunchInstanceResult) Launch(InstanceContext context) {
+		return (this, LaunchInstanceResult.InstanceIsStopping);
 	}
 
-	public IInstanceState Stop() {
-		return this; // TODO maybe provide a way to kill?
+	public (IInstanceState, StopInstanceResult) Stop(MinecraftStopStrategy stopStrategy) {
+		return (this, StopInstanceResult.InstanceAlreadyStopping); // TODO maybe provide a way to kill?
 	}
 
 	public Task<bool> SendCommand(string command, CancellationToken cancellationToken) {

Agent/Phantom.Agent.Services/Rpc/MessageListener.cs

@@ -1,9 +1,10 @@
-using NetMQ.Sockets;
-using Phantom.Agent.Rpc;
+using Phantom.Agent.Rpc;
 using Phantom.Common.Data.Replies;
+using Phantom.Common.Logging;
 using Phantom.Common.Messages;
 using Phantom.Common.Messages.ToAgent;
 using Phantom.Common.Messages.ToServer;
+using Phantom.Utils.Rpc.Message;
 using Serilog;
 
 namespace Phantom.Agent.Services.Rpc;
@@ -11,32 +12,34 @@ namespace Phantom.Agent.Services.Rpc;
 public sealed class MessageListener : IMessageToAgentListener {
 	private static ILogger Logger { get; } = PhantomLogger.Create<MessageListener>();
 
-	private readonly ClientSocket socket;
+	private readonly RpcServerConnection connection;
 	private readonly AgentServices agent;
 	private readonly CancellationTokenSource shutdownTokenSource;
 
-	public MessageListener(ClientSocket socket, AgentServices agent, CancellationTokenSource shutdownTokenSource) {
-		this.socket = socket;
+	public MessageListener(RpcServerConnection connection, AgentServices agent, CancellationTokenSource shutdownTokenSource) {
+		this.connection = connection;
 		this.agent = agent;
 		this.shutdownTokenSource = shutdownTokenSource;
 	}
 
-	public async Task HandleRegisterAgentSuccessResult(RegisterAgentSuccessMessage message) {
+	public async Task<NoReply> HandleRegisterAgentSuccess(RegisterAgentSuccessMessage message) {
 		Logger.Information("Agent authentication successful.");
 
 		foreach (var instanceInfo in message.InitialInstances) {
-			if (await agent.InstanceSessionManager.Configure(instanceInfo) != ConfigureInstanceResult.Success) {
+			var result = await agent.InstanceSessionManager.Configure(instanceInfo);
+			if (!result.Is(ConfigureInstanceResult.Success)) {
 				Logger.Fatal("Unable to configure instance \"{Name}\" (GUID {Guid}), shutting down.", instanceInfo.InstanceName, instanceInfo.InstanceGuid);
 
 				shutdownTokenSource.Cancel();
-				return;
+				return NoReply.Instance;
 			}
 		}
 
-		await ServerMessaging.SendMessage(new AdvertiseJavaRuntimesMessage(agent.JavaRuntimeRepository.All));
+		await ServerMessaging.Send(new AdvertiseJavaRuntimesMessage(agent.JavaRuntimeRepository.All));
+		return NoReply.Instance;
 	}
 
-	public Task HandleRegisterAgentFailureResult(RegisterAgentFailureMessage message) {
+	public Task<NoReply> HandleRegisterAgentFailure(RegisterAgentFailureMessage message) {
 		string errorMessage = message.FailureKind switch {
 			RegisterAgentFailure.ConnectionAlreadyHasAnAgent => "This connection already has an associated agent.",
 			RegisterAgentFailure.InvalidToken                => "Invalid token.",
@@ -46,27 +49,27 @@ public sealed class MessageListener : IMessageToAgentListener {
 		Logger.Fatal("Agent authentication failed: {Error}", errorMessage);
 		Environment.Exit(1);
 
-		return Task.CompletedTask;
+		return Task.FromResult(NoReply.Instance);
 	}
 	
-	public Task HandleShutdownAgent(ShutdownAgentMessage message) {
-		shutdownTokenSource.Cancel();
-		return Task.CompletedTask;
+	public async Task<InstanceActionResult<ConfigureInstanceResult>> HandleConfigureInstance(ConfigureInstanceMessage message) {
+		return await agent.InstanceSessionManager.Configure(message.Configuration);
 	}
 
-	public async Task HandleConfigureInstance(ConfigureInstanceMessage message) {
-		await socket.SendSimpleReply(message, await agent.InstanceSessionManager.Configure(message.Configuration));
+	public async Task<InstanceActionResult<LaunchInstanceResult>> HandleLaunchInstance(LaunchInstanceMessage message) {
+		return await agent.InstanceSessionManager.Launch(message.InstanceGuid);
 	}
 
-	public async Task HandleLaunchInstance(LaunchInstanceMessage message) {
-		await socket.SendSimpleReply(message, await agent.InstanceSessionManager.Launch(message.InstanceGuid));
+	public async Task<InstanceActionResult<StopInstanceResult>> HandleStopInstance(StopInstanceMessage message) {
+		return await agent.InstanceSessionManager.Stop(message.InstanceGuid, message.StopStrategy);
 	}
 
-	public async Task HandleStopInstance(StopInstanceMessage message) {
-		await socket.SendSimpleReply(message, await agent.InstanceSessionManager.Stop(message.InstanceGuid));
+	public async Task<InstanceActionResult<SendCommandToInstanceResult>> HandleSendCommandToInstance(SendCommandToInstanceMessage message) {
+		return await agent.InstanceSessionManager.SendCommand(message.InstanceGuid, message.Command);
 	}
 
-	public async Task HandleSendCommandToInstance(SendCommandToInstanceMessage message) {
-		await socket.SendSimpleReply(message, await agent.InstanceSessionManager.SendCommand(message.InstanceGuid, message.Command));
+	public Task<NoReply> HandleReply(ReplyMessage message) {
+		connection.Receive(message);
+		return Task.FromResult(NoReply.Instance);
 	}
 }

Agent/Phantom.Agent/AgentKey.cs

@@ -0,0 +1,60 @@
+using NetMQ;
+using Phantom.Common.Data.Agent;
+using Phantom.Common.Logging;
+using Phantom.Utils.Cryptography;
+using Phantom.Utils.IO;
+using Serilog;
+
+namespace Phantom.Agent;
+
+static class AgentKey {
+	private static ILogger Logger { get; } = PhantomLogger.Create(typeof(AgentKey));
+
+	public static Task<(NetMQCertificate, AgentAuthToken)?> Load(string? agentKeyToken, string? agentKeyFilePath) {
+		if (agentKeyFilePath != null) {
+			return LoadFromFile(agentKeyFilePath);
+		}
+		else if (agentKeyToken != null) {
+			return Task.FromResult(LoadFromToken(agentKeyToken));
+		}
+		else {
+			throw new InvalidOperationException();
+		}
+	}
+
+	private static async Task<(NetMQCertificate, AgentAuthToken)?> LoadFromFile(string agentKeyFilePath) {
+		if (!File.Exists(agentKeyFilePath)) {
+			Logger.Fatal("Missing agent key file: {AgentKeyFilePath}", agentKeyFilePath);
+			return null;
+		}
+
+		try {
+			Files.RequireMaximumFileSize(agentKeyFilePath, 64);
+			return LoadFromBytes(await File.ReadAllBytesAsync(agentKeyFilePath));
+		} catch (IOException e) {
+			Logger.Fatal("Error loading agent key from file: {AgentKeyFilePath}", agentKeyFilePath);
+			Logger.Fatal(e.Message);
+			return null;
+		} catch (Exception) {
+			Logger.Fatal("File does not contain a valid agent key: {AgentKeyFilePath}", agentKeyFilePath);
+			return null;
+		}
+	}
+
+	private static (NetMQCertificate, AgentAuthToken)? LoadFromToken(string agentKey) {
+		try {
+			return LoadFromBytes(TokenGenerator.DecodeBytes(agentKey));
+		} catch (Exception) {
+			Logger.Fatal("Invalid agent key: {AgentKey}", agentKey);
+			return null;
+		}
+	}
+
+	private static (NetMQCertificate, AgentAuthToken)? LoadFromBytes(byte[] agentKey) {
+		var (publicKey, agentToken) = AgentKeyData.FromBytes(agentKey);
+		var serverCertificate = NetMQCertificate.FromPublicKey(publicKey);
+		
+		Logger.Information("Loaded agent key.");
+		return (serverCertificate, agentToken);
+	}
+}

Agent/Phantom.Agent/CertificateFile.cs

@@ -1,32 +0,0 @@
-using NetMQ;
-using Phantom.Common.Logging;
-using Phantom.Utils.IO;
-using Serilog;
-
-namespace Phantom.Agent;
-
-static class CertificateFile {
-	private static ILogger Logger { get; } = PhantomLogger.Create(typeof(CertificateFile));
-
-	public static async Task<NetMQCertificate?> LoadPublicKey(string publicKeyFilePath) {
-		if (!File.Exists(publicKeyFilePath)) {
-			Logger.Fatal("Cannot load server certificate, missing key file: {PublicKeyFilePath}", publicKeyFilePath);
-			return null;
-		}
-
-		try {
-			var publicKey = await LoadPublicKeyFromFile(publicKeyFilePath);
-			Logger.Information("Loaded server certificate.");
-			return publicKey;
-		} catch (Exception e) {
-			Logger.Fatal(e, "Error loading server certificate from key file: {PublicKeyFilePath}", publicKeyFilePath);
-			return null;
-		}
-	}
-
-	private static async Task<NetMQCertificate> LoadPublicKeyFromFile(string filePath) {
-		Files.RequireMaximumFileSize(filePath, 1024);
-		byte[] publicKey = await File.ReadAllBytesAsync(filePath);
-		return NetMQCertificate.FromPublicKey(publicKey);
-	}
-}

Agent/Phantom.Agent/Phantom.Agent.csproj

@@ -8,6 +8,7 @@
   
   <PropertyGroup>
     <OutputType>Exe</OutputType>
+    <SatelliteResourceLanguages>en</SatelliteResourceLanguages>
   </PropertyGroup>
   
   <ItemGroup>

Agent/Phantom.Agent/Program.cs

@@ -1,4 +1,5 @@
-using Phantom.Agent;
+using System.Reflection;
+using Phantom.Agent;
 using Phantom.Agent.Rpc;
 using Phantom.Agent.Services;
 using Phantom.Agent.Services.Rpc;
@@ -7,31 +8,25 @@ using Phantom.Common.Logging;
 using Phantom.Utils.Rpc;
 using Phantom.Utils.Runtime;
 
-const int AgentVersion = 1;
+const int ProtocolVersion = 1;
 
-var cancellationTokenSource = new CancellationTokenSource();
+var shutdownCancellationTokenSource = new CancellationTokenSource();
+var shutdownCancellationToken = shutdownCancellationTokenSource.Token;
 
-PosixSignals.RegisterCancellation(cancellationTokenSource, static () => {
+PosixSignals.RegisterCancellation(shutdownCancellationTokenSource, static () => {
 	PhantomLogger.Root.InformationHeading("Stopping Phantom Panel agent...");
 });
 
 try {
+	var fullVersion = AssemblyAttributes.GetFullVersion(Assembly.GetExecutingAssembly());
+
 	PhantomLogger.Root.InformationHeading("Initializing Phantom Panel agent...");
+	PhantomLogger.Root.Information("Agent version: {Version}", fullVersion);
 
-	var (serverHost, serverPort, javaSearchPath, authToken, authTokenFilePath, agentName, maxInstances, maxMemory, allowedServerPorts, allowedRconPorts) = Variables.LoadOrExit();
-	
-	AgentAuthToken agentAuthToken;
-	try {
-		agentAuthToken = authTokenFilePath == null ? new AgentAuthToken(authToken) : await AgentAuthToken.ReadFromFile(authTokenFilePath);
-	} catch (Exception e) {
-		PhantomLogger.Root.Fatal(e, "Error reading auth token.");
-		Environment.Exit(1);
-		return;
-	}
+	var (serverHost, serverPort, javaSearchPath, agentKeyToken, agentKeyFilePath, agentName, maxInstances, maxMemory, allowedServerPorts, allowedRconPorts) = Variables.LoadOrExit();
 
-	string serverPublicKeyPath = Path.GetFullPath("./secrets/agent.key");
-	var serverCertificate = await CertificateFile.LoadPublicKey(serverPublicKeyPath);
-	if (serverCertificate == null) {
+	var agentKey = await AgentKey.Load(agentKeyToken, agentKeyFilePath);
+	if (agentKey == null) {
 		Environment.Exit(1);
 	}
 
@@ -43,21 +38,39 @@ try {
 	var agentGuid = await GuidFile.CreateOrLoad(folders.DataFolderPath);
 	if (agentGuid == null) {
 		Environment.Exit(1);
-		return;
 	}
 
-	var agentInfo = new AgentInfo(agentGuid.Value, agentName, AgentVersion, maxInstances, maxMemory, allowedServerPorts, allowedRconPorts);
+	var (serverCertificate, agentToken) = agentKey.Value;
+	var agentInfo = new AgentInfo(agentGuid.Value, agentName, ProtocolVersion, fullVersion, maxInstances, maxMemory, allowedServerPorts, allowedRconPorts);
 	var agentServices = new AgentServices(agentInfo, folders);
 
+	MessageListener MessageListenerFactory(RpcServerConnection connection) {
+		return new MessageListener(connection, agentServices, shutdownCancellationTokenSource);
+	}
+
 	PhantomLogger.Root.InformationHeading("Launching Phantom Panel agent...");
-	
+
 	await agentServices.Initialize();
-	await RpcLauncher.Launch(new RpcConfiguration(PhantomLogger.Create("Rpc"), serverHost, serverPort, serverCertificate, cancellationTokenSource.Token), agentAuthToken, agentInfo, socket => new MessageListener(socket, agentServices, cancellationTokenSource));
-	await agentServices.Shutdown();
+
+	var rpcDisconnectSemaphore = new SemaphoreSlim(0, 1);
+	var rpcTask = RpcLauncher.Launch(new RpcConfiguration(PhantomLogger.Create("Rpc"), serverHost, serverPort, serverCertificate), agentToken, agentInfo, MessageListenerFactory, rpcDisconnectSemaphore, shutdownCancellationToken);
+	try {
+		await rpcTask.WaitAsync(shutdownCancellationToken);
+	} finally {
+		shutdownCancellationTokenSource.Cancel();
+		await agentServices.Shutdown();
+
+		rpcDisconnectSemaphore.Release();
+		await rpcTask;
+		rpcDisconnectSemaphore.Dispose();
+	}
 } catch (OperationCanceledException) {
 	// Ignore.
+} catch (Exception e) {
+	PhantomLogger.Root.Fatal(e, "Caught exception in entry point.");
 } finally {
-	cancellationTokenSource.Dispose();
+	shutdownCancellationTokenSource.Dispose();
+
 	PhantomLogger.Root.Information("Bye!");
 	PhantomLogger.Dispose();
 }

Agent/Phantom.Agent/Variables.cs

@@ -9,8 +9,8 @@ sealed record Variables(
 	string ServerHost,
 	ushort ServerPort,
 	string JavaSearchPath,
-	string? AuthToken,
-	string? AuthTokenFilePath,
+	string? AgentKeyToken,
+	string? AgentKeyFilePath,
 	string AgentName,
 	ushort MaxInstances,
 	RamAllocationUnits MaxMemory,
@@ -18,20 +18,20 @@ sealed record Variables(
 	AllowedPorts AllowedRconPorts
 ) {
 	private static Variables LoadOrThrow() {
-		var (authToken, authTokenFilePath) = EnvironmentVariables.GetEitherString("SERVER_AUTH_TOKEN", "SERVER_AUTH_TOKEN_FILE").OrThrow;
-		var javaSearchPath = EnvironmentVariables.GetString("JAVA_SEARCH_PATH").OrGetDefault(GetDefaultJavaSearchPath);
+		var (agentKeyToken, agentKeyFilePath) = EnvironmentVariables.GetEitherString("AGENT_KEY", "AGENT_KEY_FILE").Require;
+		var javaSearchPath = EnvironmentVariables.GetString("JAVA_SEARCH_PATH").WithDefaultGetter(GetDefaultJavaSearchPath);
 
 		return new Variables(
-			EnvironmentVariables.GetString("SERVER_HOST").OrThrow,
-			EnvironmentVariables.GetPortNumber("SERVER_PORT").OrDefault(9401),
+			EnvironmentVariables.GetString("SERVER_HOST").Require,
+			EnvironmentVariables.GetPortNumber("SERVER_PORT").WithDefault(9401),
 			javaSearchPath,
-			authToken,
-			authTokenFilePath,
-			EnvironmentVariables.GetString("AGENT_NAME").OrThrow,
-			(ushort) EnvironmentVariables.GetInteger("MAX_INSTANCES", min: 1, max: 10000).OrThrow,
-			EnvironmentVariables.GetString("MAX_MEMORY").MapParse(RamAllocationUnits.FromString).OrThrow,
-			EnvironmentVariables.GetString("ALLOWED_SERVER_PORTS").MapParse(AllowedPorts.FromString).OrThrow,
-			EnvironmentVariables.GetString("ALLOWED_RCON_PORTS").MapParse(AllowedPorts.FromString).OrThrow
+			agentKeyToken,
+			agentKeyFilePath,
+			EnvironmentVariables.GetString("AGENT_NAME").Require,
+			(ushort) EnvironmentVariables.GetInteger("MAX_INSTANCES", min: 1, max: 10000).Require,
+			EnvironmentVariables.GetString("MAX_MEMORY").MapParse(RamAllocationUnits.FromString).Require,
+			EnvironmentVariables.GetString("ALLOWED_SERVER_PORTS").MapParse(AllowedPorts.FromString).Require,
+			EnvironmentVariables.GetString("ALLOWED_RCON_PORTS").MapParse(AllowedPorts.FromString).Require
 		);
 	}
 

Common/Phantom.Common.Data.Tests/Phantom.Common.Data.Tests.csproj

@@ -11,11 +11,11 @@
   </PropertyGroup>
   
   <ItemGroup>
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.3.2" />
-    <PackageReference Include="NUnit" Version="3.13.3" />
-    <PackageReference Include="NUnit3TestAdapter" Version="4.2.1" />
-    <PackageReference Include="NUnit.Analyzers" Version="3.3.0" />
-    <PackageReference Include="coverlet.collector" Version="3.1.2" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" />
+    <PackageReference Include="NUnit" />
+    <PackageReference Include="NUnit3TestAdapter" />
+    <PackageReference Include="NUnit.Analyzers" />
+    <PackageReference Include="coverlet.collector" />
   </ItemGroup>
   
   <ItemGroup>

Common/Phantom.Common.Data/Agent/AgentAuthToken.cs

@@ -1,56 +1,39 @@
 using System.Diagnostics.CodeAnalysis;
 using System.Security.Cryptography;
-using System.Text;
-using MessagePack;
-using Phantom.Utils.Cryptography;
-using Phantom.Utils.IO;
+using MemoryPack;
 
 namespace Phantom.Common.Data.Agent;
 
-[MessagePackObject]
+[MemoryPackable]
 [SuppressMessage("ReSharper", "MemberCanBePrivate.Global")]
-public sealed class AgentAuthToken {
-	private const int MinimumTokenLength = 30;
-	private const int MaximumTokenLength = 100;
+public sealed partial class AgentAuthToken {
+	internal const int Length = 12;
 
-	[Key(0)]
-	public string Value { get; }
-
-	[IgnoreMember]
+	[MemoryPackOrder(0)]
+	[MemoryPackInclude]
 	private readonly byte[] bytes;
 
-	public AgentAuthToken(string? value) {
-		if (value == null) {
-			throw new ArgumentNullException(nameof(value));
+	public AgentAuthToken(byte[]? bytes) {
+		if (bytes == null) {
+			throw new ArgumentNullException(nameof(bytes));
 		}
 
-		if (value.Length is < MinimumTokenLength or > MaximumTokenLength) {
-			throw new ArgumentOutOfRangeException(nameof(value), "Invalid token length: " + value.Length + ". Token length must be between " + MinimumTokenLength + " and " + MaximumTokenLength + ".");
+		if (bytes.Length != Length) {
+			throw new ArgumentOutOfRangeException(nameof(bytes), "Invalid token length: " + bytes.Length + ". Token length must be exactly " + Length + " bytes.");
 		}
 
-		this.Value = value;
-		this.bytes = TokenGenerator.GetBytesOrThrow(value);
+		this.bytes = bytes;
 	}
 
 	public bool FixedTimeEquals(AgentAuthToken providedAuthToken) {
 		return CryptographicOperations.FixedTimeEquals(bytes, providedAuthToken.bytes);
 	}
 
-	public override string ToString() {
-		return Value;
-	}
-
-	public async Task WriteToFile(string filePath) {
-		await Files.WriteBytesAsync(filePath, bytes, FileMode.Create, Chmod.URW_GR);
-	}
-
-	public static async Task<AgentAuthToken> ReadFromFile(string filePath) {
-		Files.RequireMaximumFileSize(filePath, MaximumTokenLength + 1);
-		string contents = await File.ReadAllTextAsync(filePath, Encoding.ASCII);
-		return new AgentAuthToken(contents.Trim());
+	internal void WriteTo(Span<byte> span) {
+		bytes.CopyTo(span);
 	}
 
 	public static AgentAuthToken Generate() {
-		return new AgentAuthToken(TokenGenerator.Create(MinimumTokenLength));
+		return new AgentAuthToken(RandomNumberGenerator.GetBytes(Length));
 	}
 }

Common/Phantom.Common.Data/Agent/AgentInfo.cs

@@ -1,14 +1,15 @@
-using MessagePack;
+using MemoryPack;
 
 namespace Phantom.Common.Data.Agent;
 
-[MessagePackObject]
-public sealed record AgentInfo(
-	[property: Key(0)] Guid Guid,
-	[property: Key(1)] string Name,
-	[property: Key(2)] ushort Version,
-	[property: Key(3)] ushort MaxInstances,
-	[property: Key(4)] RamAllocationUnits MaxMemory,
-	[property: Key(5)] AllowedPorts AllowedServerPorts,
-	[property: Key(6)] AllowedPorts AllowedRconPorts
+[MemoryPackable]
+public sealed partial record AgentInfo(
+	[property: MemoryPackOrder(0)] Guid Guid,
+	[property: MemoryPackOrder(1)] string Name,
+	[property: MemoryPackOrder(2)] ushort ProtocolVersion,
+	[property: MemoryPackOrder(3)] string BuildVersion,
+	[property: MemoryPackOrder(4)] ushort MaxInstances,
+	[property: MemoryPackOrder(5)] RamAllocationUnits MaxMemory,
+	[property: MemoryPackOrder(6)] AllowedPorts AllowedServerPorts,
+	[property: MemoryPackOrder(7)] AllowedPorts AllowedRconPorts
 );

Common/Phantom.Common.Data/Agent/AgentKeyData.cs

@@ -0,0 +1,18 @@
+namespace Phantom.Common.Data.Agent;
+
+public static class AgentKeyData {
+	private const byte TokenLength = AgentAuthToken.Length;
+
+	public static byte[] ToBytes(byte[] publicKey, AgentAuthToken agentToken) {
+		Span<byte> agentKey = stackalloc byte[TokenLength + publicKey.Length];
+		agentToken.WriteTo(agentKey[..TokenLength]);
+		publicKey.CopyTo(agentKey[TokenLength..]);
+		return agentKey.ToArray();
+	}
+
+	public static (byte[] PublicKey, AgentAuthToken AgentToken) FromBytes(byte[] agentKey) {
+		var token = new AgentAuthToken(agentKey[..TokenLength]);
+		var publicKey = agentKey[TokenLength..];
+		return (publicKey, token);
+	}
+}

Common/Phantom.Common.Data/AllowedPorts.cs

@@ -1,29 +1,28 @@
 using System.Collections.Immutable;
-using System.Diagnostics.CodeAnalysis;
 using System.Text;
-using MessagePack;
+using MemoryPack;
 
 namespace Phantom.Common.Data;
 
-[MessagePackObject]
-[SuppressMessage("ReSharper", "MemberCanBePrivate.Global")]
-public sealed class AllowedPorts {
-	[Key(0)]
-	public ImmutableArray<PortRange> AllDefinitions { get; }
+[MemoryPackable]
+public sealed partial class AllowedPorts {
+	[MemoryPackOrder(0)]
+	[MemoryPackInclude]
+	private	readonly ImmutableArray<PortRange> allDefinitions;
 
-	public AllowedPorts(ImmutableArray<PortRange> allDefinitions) {
+	private AllowedPorts(ImmutableArray<PortRange> allDefinitions) {
 		// TODO normalize and deduplicate ranges
-		this.AllDefinitions = allDefinitions.Sort(static (def1, def2) => def1.FirstPort - def2.FirstPort);
+		this.allDefinitions = allDefinitions.Sort(static (def1, def2) => def1.FirstPort - def2.FirstPort);
 	}
 
 	public bool Contains(ushort port) {
-		return AllDefinitions.Any(definition => definition.Contains(port));
+		return allDefinitions.Any(definition => definition.Contains(port));
 	}
 
 	public override string ToString() {
 		var builder = new StringBuilder();
 
-		foreach (var definition in AllDefinitions) {
+		foreach (var definition in allDefinitions) {
 			definition.ToString(builder);
 			builder.Append(',');
 		}
@@ -35,53 +34,7 @@ public sealed class AllowedPorts {
 		return builder.ToString();
 	}
 
-	[MessagePackObject]
-	public readonly record struct PortRange(
-		[property: Key(0)] ushort FirstPort,
-		[property: Key(1)] ushort LastPort
-	) {
-		private PortRange(ushort port) : this(port, port) {}
-
-		internal bool Contains(ushort port) {
-			return port >= FirstPort && port <= LastPort;
-		}
-
-		internal void ToString(StringBuilder builder) {
-			builder.Append(FirstPort);
-
-			if (LastPort != FirstPort) {
-				builder.Append('-');
-				builder.Append(LastPort);
-			}
-		}
-
-		internal static PortRange Parse(ReadOnlySpan<char> definition) {
-			int separatorIndex = definition.IndexOf('-');
-			if (separatorIndex == -1) {
-				var port = ParsePort(definition.Trim());
-				return new PortRange(port);
-			}
-
-			var firstPort = ParsePort(definition[..separatorIndex].Trim());
-			var lastPort = ParsePort(definition[(separatorIndex + 1)..].Trim());
-			if (lastPort < firstPort) {
-				throw new FormatException("Invalid port range '" + firstPort + "-" + lastPort + "'.");
-			}
-			else {
-				return new PortRange(firstPort, lastPort);
-			}
-		}
-
-		private static ushort ParsePort(ReadOnlySpan<char> port) {
-			try {
-				return ushort.Parse(port);
-			} catch (Exception) {
-				throw new FormatException("Invalid port '" + port.ToString() + "'.");
-			}
-		}
-	}
-
-	public static AllowedPorts FromString(ReadOnlySpan<char> definitions) {
+	private static AllowedPorts FromString(ReadOnlySpan<char> definitions) {
 		List<PortRange> parsedDefinitions = new ();
 
 		while (!definitions.IsEmpty) {

Common/Phantom.Common.Data/Instance/IInstanceStatus.cs

@@ -0,0 +1,67 @@
+using MemoryPack;
+
+namespace Phantom.Common.Data.Instance;
+
+[MemoryPackable]
+[MemoryPackUnion(0, typeof(InstanceIsOffline))]
+[MemoryPackUnion(1, typeof(InstanceIsInvalid))]
+[MemoryPackUnion(2, typeof(InstanceIsNotRunning))]
+[MemoryPackUnion(3, typeof(InstanceIsDownloading))]
+[MemoryPackUnion(4, typeof(InstanceIsLaunching))]
+[MemoryPackUnion(5, typeof(InstanceIsRunning))]
+[MemoryPackUnion(6, typeof(InstanceIsRestarting))]
+[MemoryPackUnion(7, typeof(InstanceIsStopping))]
+[MemoryPackUnion(8, typeof(InstanceIsFailed))]
+public partial interface IInstanceStatus {}
+
+[MemoryPackable]
+public sealed partial record InstanceIsOffline : IInstanceStatus;
+
+[MemoryPackable]
+public sealed partial record InstanceIsInvalid([property: MemoryPackOrder(0)] string Reason) : IInstanceStatus;
+
+[MemoryPackable]
+public sealed partial record InstanceIsNotRunning : IInstanceStatus;
+
+[MemoryPackable]
+public sealed partial record InstanceIsDownloading([property: MemoryPackOrder(0)] byte Progress) : IInstanceStatus;
+
+[MemoryPackable]
+public sealed partial record InstanceIsLaunching : IInstanceStatus;
+
+[MemoryPackable]
+public sealed partial record InstanceIsRunning : IInstanceStatus;
+
+[MemoryPackable]
+public sealed partial record InstanceIsRestarting : IInstanceStatus;
+
+[MemoryPackable]
+public sealed partial record InstanceIsStopping : IInstanceStatus;
+
+[MemoryPackable]
+public sealed partial record InstanceIsFailed([property: MemoryPackOrder(0)] InstanceLaunchFailReason Reason) : IInstanceStatus;
+
+public static class InstanceStatus {
+	public static readonly IInstanceStatus Offline = new InstanceIsOffline();
+	public static readonly IInstanceStatus NotRunning = new InstanceIsNotRunning();
+	public static readonly IInstanceStatus Launching = new InstanceIsLaunching();
+	public static readonly IInstanceStatus Running = new InstanceIsRunning();
+	public static readonly IInstanceStatus Restarting = new InstanceIsRestarting();
+	public static readonly IInstanceStatus Stopping = new InstanceIsStopping();
+	
+	public static IInstanceStatus Invalid(string reason) => new InstanceIsInvalid(reason);
+	public static IInstanceStatus Downloading(byte progress) => new InstanceIsDownloading(progress);
+	public static IInstanceStatus Failed(InstanceLaunchFailReason reason) => new InstanceIsFailed(reason);
+	
+	public static bool CanLaunch(this IInstanceStatus status) {
+		return status is InstanceIsNotRunning or InstanceIsFailed;
+	}
+
+	public static bool CanStop(this IInstanceStatus status) {
+		return status is InstanceIsDownloading or InstanceIsLaunching or InstanceIsRunning;
+	}
+
+	public static bool CanSendCommand(this IInstanceStatus status) {
+		return status is InstanceIsRunning;
+	}
+}

Common/Phantom.Common.Data/Instance/InstanceConfiguration.cs

@@ -1,18 +1,20 @@
-using MessagePack;
+using System.Collections.Immutable;
+using MemoryPack;
 using Phantom.Common.Data.Minecraft;
 
-namespace Phantom.Common.Data.Instance; 
+namespace Phantom.Common.Data.Instance;
 
-[MessagePackObject]
-public sealed record InstanceConfiguration(
-	[property: Key(0)] Guid AgentGuid,
-	[property: Key(1)] Guid InstanceGuid,
-	[property: Key(2)] string InstanceName,
-	[property: Key(3)] ushort ServerPort,
-	[property: Key(4)] ushort RconPort,
-	[property: Key(5)] string MinecraftVersion,
-	[property: Key(6)] MinecraftServerKind MinecraftServerKind,
-	[property: Key(7)] RamAllocationUnits MemoryAllocation,
-	[property: Key(8)] Guid JavaRuntimeGuid,
-	[property: Key(9)] bool LaunchAutomatically
+[MemoryPackable]
+public sealed partial record InstanceConfiguration(
+	[property: MemoryPackOrder(0)] Guid AgentGuid,
+	[property: MemoryPackOrder(1)] Guid InstanceGuid,
+	[property: MemoryPackOrder(2)] string InstanceName,
+	[property: MemoryPackOrder(3)] ushort ServerPort,
+	[property: MemoryPackOrder(4)] ushort RconPort,
+	[property: MemoryPackOrder(5)] string MinecraftVersion,
+	[property: MemoryPackOrder(6)] MinecraftServerKind MinecraftServerKind,
+	[property: MemoryPackOrder(7)] RamAllocationUnits MemoryAllocation,
+	[property: MemoryPackOrder(8)] Guid JavaRuntimeGuid,
+	[property: MemoryPackOrder(9)] ImmutableArray<string> JvmArguments,
+	[property: MemoryPackOrder(10)] bool LaunchAutomatically
 );

Common/Phantom.Common.Data/Instance/InstanceLaunchFailReason.cs

@@ -1,25 +1,31 @@
 namespace Phantom.Common.Data.Instance;
 
 public enum InstanceLaunchFailReason {
+	UnknownError,
 	ServerPortNotAllowed,
 	ServerPortAlreadyInUse,
 	RconPortNotAllowed,
 	RconPortAlreadyInUse,
 	JavaRuntimeNotFound,
+	InvalidJvmArguments,
 	CouldNotDownloadMinecraftServer,
-	UnknownError
+	CouldNotConfigureMinecraftServer,
+	CouldNotStartMinecraftServer
 }
 
 public static class InstanceLaunchFailReasonExtensions {
 	public static string ToSentence(this InstanceLaunchFailReason reason) {
 		return reason switch {
-			InstanceLaunchFailReason.ServerPortNotAllowed            => "Server port not allowed.",
-			InstanceLaunchFailReason.ServerPortAlreadyInUse          => "Server port already in use.",
-			InstanceLaunchFailReason.RconPortNotAllowed              => "Rcon port not allowed.",
-			InstanceLaunchFailReason.RconPortAlreadyInUse            => "Rcon port already in use.",
-			InstanceLaunchFailReason.JavaRuntimeNotFound             => "Java runtime not found.",
-			InstanceLaunchFailReason.CouldNotDownloadMinecraftServer => "Could not download Minecraft server.",
-			_                                                        => "Unknown error."
+			InstanceLaunchFailReason.ServerPortNotAllowed             => "Server port not allowed.",
+			InstanceLaunchFailReason.ServerPortAlreadyInUse           => "Server port already in use.",
+			InstanceLaunchFailReason.RconPortNotAllowed               => "Rcon port not allowed.",
+			InstanceLaunchFailReason.RconPortAlreadyInUse             => "Rcon port already in use.",
+			InstanceLaunchFailReason.JavaRuntimeNotFound              => "Java runtime not found.",
+			InstanceLaunchFailReason.InvalidJvmArguments              => "Invalid JVM arguments.",
+			InstanceLaunchFailReason.CouldNotDownloadMinecraftServer  => "Could not download Minecraft server.",
+			InstanceLaunchFailReason.CouldNotConfigureMinecraftServer => "Could not configure Minecraft server.",
+			InstanceLaunchFailReason.CouldNotStartMinecraftServer     => "Could not start Minecraft server.",
+			_                                                         => "Unknown error."
 		};
 	}
 }

Common/Phantom.Common.Data/Instance/InstanceStatus.cs

@@ -1,63 +0,0 @@
-using MessagePack;
-
-namespace Phantom.Common.Data.Instance;
-
-[Union(0, typeof(Offline))]
-[Union(1, typeof(Invalid))]
-[Union(2, typeof(NotRunning))]
-[Union(3, typeof(Downloading))]
-[Union(4, typeof(Launching))]
-[Union(5, typeof(Running))]
-[Union(6, typeof(Stopping))]
-[Union(7, typeof(Failed))]
-public abstract record InstanceStatus {
-	public static readonly InstanceStatus IsOffline = new Offline();
-	public static readonly InstanceStatus IsNotRunning = new NotRunning();
-	public static readonly InstanceStatus IsLaunching = new Launching();
-	public static readonly InstanceStatus IsRunning = new Running();
-	public static readonly InstanceStatus IsStopping = new Stopping();
-
-	[MessagePackObject]
-	public sealed record Offline : InstanceStatus;
-
-	[MessagePackObject]
-	public sealed record Invalid(
-		[property: Key(0)] string Reason
-	) : InstanceStatus;
-
-	[MessagePackObject]
-	public sealed record NotRunning : InstanceStatus;
-
-	[MessagePackObject]
-	public sealed record Downloading(
-		[property: Key(0)] byte Progress
-	) : InstanceStatus;
-
-	[MessagePackObject]
-	public sealed record Launching : InstanceStatus;
-	
-	[MessagePackObject]
-	public sealed record Running : InstanceStatus;
-
-	[MessagePackObject]
-	public sealed record Stopping : InstanceStatus;
-
-	[MessagePackObject]
-	public sealed record Failed(
-		[property: Key(0)] InstanceLaunchFailReason Reason
-	) : InstanceStatus;
-}
-
-public static class InstanceStatusExtensions {
-	public static bool CanLaunch(this InstanceStatus status) {
-		return status is InstanceStatus.NotRunning or InstanceStatus.Failed;
-	}
-
-	public static bool CanStop(this InstanceStatus status) {
-		return status is InstanceStatus.Downloading or InstanceStatus.Launching or InstanceStatus.Running;
-	}
-
-	public static bool CanSendCommand(this InstanceStatus status) {
-		return status is InstanceStatus.Running;
-	}
-}

Common/Phantom.Common.Data/Java/JavaRuntime.cs

@@ -1,13 +1,13 @@
 using System.Diagnostics.CodeAnalysis;
-using MessagePack;
+using MemoryPack;
 
 namespace Phantom.Common.Data.Java;
 
-[MessagePackObject]
-public sealed record JavaRuntime(
-	[property: Key(0)] string MainVersion,
-	[property: Key(1)] string FullVersion,
-	[property: Key(2)] string DisplayName
+[MemoryPackable]
+public sealed partial record JavaRuntime(
+	[property: MemoryPackOrder(0)] string MainVersion,
+	[property: MemoryPackOrder(1)] string FullVersion,
+	[property: MemoryPackOrder(2)] string DisplayName
 ) : IComparable<JavaRuntime> {
 	public int CompareTo(JavaRuntime? other) {
 		if (ReferenceEquals(this, other)) {

Common/Phantom.Common.Data/Java/TaggedJavaRuntime.cs

@@ -1,9 +1,9 @@
-using MessagePack;
+using MemoryPack;
 
 namespace Phantom.Common.Data.Java; 
 
-[MessagePackObject]
-public sealed record TaggedJavaRuntime(
-	[property: Key(0)] Guid Guid,
-	[property: Key(1)] JavaRuntime Runtime
+[MemoryPackable]
+public sealed partial record TaggedJavaRuntime(
+	[property: MemoryPackOrder(0)] Guid Guid,
+	[property: MemoryPackOrder(1)] JavaRuntime Runtime
 );

Common/Phantom.Common.Data/Minecraft/MinecraftStopStrategy.cs

@@ -0,0 +1,10 @@
+using MemoryPack;
+
+namespace Phantom.Common.Data.Minecraft;
+
+[MemoryPackable]
+public readonly partial record struct MinecraftStopStrategy(
+	[property: MemoryPackOrder(0)] ushort Seconds
+) {
+	public static MinecraftStopStrategy Instant => new (0);
+}

Common/Phantom.Common.Data/Minecraft/MinecraftVersion.cs

@@ -0,0 +1,7 @@
+namespace Phantom.Common.Data.Minecraft; 
+
+public sealed record MinecraftVersion(
+	string Id,
+	MinecraftVersionType Type,
+	string MetadataUrl
+);

Common/Phantom.Common.Data/Minecraft/MinecraftVersionType.cs

@@ -0,0 +1,38 @@
+using System.Collections.Immutable;
+
+namespace Phantom.Common.Data.Minecraft;
+
+public enum MinecraftVersionType : ushort {
+	Other = 0,
+	Release = 1,
+	Snapshot = 2,
+	OldBeta = 3,
+	OldAlpha = 4
+}
+
+public static class MinecraftVersionTypes {
+	public static readonly ImmutableArray<MinecraftVersionType> WithServerJars = ImmutableArray.Create(
+		MinecraftVersionType.Release,
+		MinecraftVersionType.Snapshot
+	);
+
+	public static MinecraftVersionType FromString(string? type) {
+		return type switch {
+			"release"   => MinecraftVersionType.Release,
+			"snapshot"  => MinecraftVersionType.Snapshot,
+			"old_beta"  => MinecraftVersionType.OldBeta,
+			"old_alpha" => MinecraftVersionType.OldAlpha,
+			_           => MinecraftVersionType.Other
+		};
+	}
+
+	public static string ToNiceNamePlural(this MinecraftVersionType type) {
+		return type switch {
+			MinecraftVersionType.Release  => "Releases",
+			MinecraftVersionType.Snapshot => "Snapshots",
+			MinecraftVersionType.OldBeta  => "Beta",
+			MinecraftVersionType.OldAlpha => "Alpha",
+			_                             => "Unknown"
+		};
+	}
+}

Common/Phantom.Common.Data/Phantom.Common.Data.csproj

@@ -7,7 +7,7 @@
   </PropertyGroup>
   
   <ItemGroup>
-    <PackageReference Include="MessagePack.Annotations" Version="2.4.35" />
+    <PackageReference Include="MemoryPack" />
   </ItemGroup>
   
   <ItemGroup>

Common/Phantom.Common.Data/PortRange.cs

@@ -0,0 +1,48 @@
+using System.Text;
+using MemoryPack;
+
+namespace Phantom.Common.Data;
+
+[MemoryPackable]
+public readonly partial record struct PortRange(
+	[property: MemoryPackOrder(0)] ushort FirstPort,
+	[property: MemoryPackOrder(1)] ushort LastPort
+) {
+	internal bool Contains(ushort port) {
+		return port >= FirstPort && port <= LastPort;
+	}
+
+	internal void ToString(StringBuilder builder) {
+		builder.Append(FirstPort);
+
+		if (LastPort != FirstPort) {
+			builder.Append('-');
+			builder.Append(LastPort);
+		}
+	}
+
+	internal static PortRange Parse(ReadOnlySpan<char> definition) {
+		int separatorIndex = definition.IndexOf('-');
+		if (separatorIndex == -1) {
+			var port = ParsePort(definition.Trim());
+			return new PortRange(port, port);
+		}
+
+		var firstPort = ParsePort(definition[..separatorIndex].Trim());
+		var lastPort = ParsePort(definition[(separatorIndex + 1)..].Trim());
+		if (lastPort < firstPort) {
+			throw new FormatException("Invalid port range '" + firstPort + "-" + lastPort + "'.");
+		}
+		else {
+			return new PortRange(firstPort, lastPort);
+		}
+	}
+
+	private static ushort ParsePort(ReadOnlySpan<char> port) {
+		try {
+			return ushort.Parse(port);
+		} catch (Exception) {
+			throw new FormatException("Invalid port '" + port.ToString() + "'.");
+		}
+	}
+}

Common/Phantom.Common.Data/RamAllocationUnits.cs

@@ -1,17 +1,17 @@
 using System.Diagnostics.CodeAnalysis;
-using MessagePack;
+using MemoryPack;
 
 namespace Phantom.Common.Data;
 
 /// <summary>
 /// Represents a number of RAM allocation units, using the conversion factor of 256 MB per unit. Supports allocations up to 16 TB minus 256 MB (65535 units).
 /// </summary>
-[MessagePackObject]
+[MemoryPackable]
 [SuppressMessage("ReSharper", "MemberCanBePrivate.Global")]
-public readonly record struct RamAllocationUnits(
-	[property: Key(0)] ushort RawValue
+public readonly partial record struct RamAllocationUnits(
+	[property: MemoryPackOrder(0)] ushort RawValue
 ) : IComparable<RamAllocationUnits> {
-	[IgnoreMember]
+	[MemoryPackIgnore]
 	public uint InMegabytes => (uint) RawValue * MegabytesPerUnit;
 
 	public int CompareTo(RamAllocationUnits other) {

Common/Phantom.Common.Data/Replies/ConfigureInstanceResult.cs

@@ -2,7 +2,6 @@
 
 public enum ConfigureInstanceResult {
 	Success,
-	AgentShuttingDown,
 	InstanceLimitExceeded,
 	MemoryLimitExceeded
 }

Common/Phantom.Common.Data/Replies/InstanceActionGeneralResult.cs

@@ -0,0 +1,8 @@
+namespace Phantom.Common.Data.Replies;
+
+public enum InstanceActionGeneralResult : byte {
+	None,
+	AgentShuttingDown,
+	AgentIsNotResponding,
+	InstanceDoesNotExist
+}

Common/Phantom.Common.Data/Replies/InstanceActionResult.cs

@@ -0,0 +1,41 @@
+using MemoryPack;
+
+namespace Phantom.Common.Data.Replies;
+
+[MemoryPackable]
+public sealed partial record InstanceActionResult<T>(
+	[property: MemoryPackOrder(0)] InstanceActionGeneralResult GeneralResult,
+	[property: MemoryPackOrder(1)] T? ConcreteResult
+) {
+	public bool Is(T? concreteResult) {
+		return GeneralResult == InstanceActionGeneralResult.None && EqualityComparer<T>.Default.Equals(ConcreteResult, concreteResult);
+	}
+
+	public InstanceActionResult<T2> Map<T2>(Func<T, T2> mapper) {
+		return new InstanceActionResult<T2>(GeneralResult, ConcreteResult is not null ? mapper(ConcreteResult) : default);
+	}
+
+	public string ToSentence(Func<T, string> concreteResultToSentence) {
+		return GeneralResult switch {
+			InstanceActionGeneralResult.None                 => concreteResultToSentence(ConcreteResult!),
+			InstanceActionGeneralResult.AgentShuttingDown    => "Agent is shutting down.",
+			InstanceActionGeneralResult.AgentIsNotResponding => "Agent is not responding.",
+			InstanceActionGeneralResult.InstanceDoesNotExist => "Instance does not exist.",
+			_                                                => "Unknown result."
+		};
+	}
+}
+
+public static class InstanceActionResult {
+	public static InstanceActionResult<T> General<T>(InstanceActionGeneralResult generalResult) {
+		return new InstanceActionResult<T>(generalResult, default);
+	}
+
+	public static InstanceActionResult<T> Concrete<T>(T? concreteResult) {
+		return new InstanceActionResult<T>(InstanceActionGeneralResult.None, concreteResult);
+	}
+
+	public static InstanceActionResult<T> DidNotReplyIfNull<T>(this InstanceActionResult<T>? result) {
+		return result ?? General<T>(InstanceActionGeneralResult.AgentIsNotResponding);
+	}
+}

Common/Phantom.Common.Data/Replies/LaunchInstanceResult.cs

@@ -2,12 +2,9 @@
 
 public enum LaunchInstanceResult {
 	LaunchInitiated,
-	AgentShuttingDown,
-	InstanceDoesNotExist,
 	InstanceAlreadyLaunching,
 	InstanceAlreadyRunning,
 	InstanceIsStopping,
-	CommunicationError,
 	UnknownError
 }
 
@@ -15,12 +12,9 @@ public static class LaunchInstanceResultExtensions {
 	public static string ToSentence(this LaunchInstanceResult reason) {
 		return reason switch {
 			LaunchInstanceResult.LaunchInitiated          => "Launch initiated.",
-			LaunchInstanceResult.AgentShuttingDown        => "Agent is shutting down.",
-			LaunchInstanceResult.InstanceDoesNotExist     => "Instance does not exist.",
 			LaunchInstanceResult.InstanceAlreadyLaunching => "Instance is already launching.",
 			LaunchInstanceResult.InstanceAlreadyRunning   => "Instance is already running.",
 			LaunchInstanceResult.InstanceIsStopping       => "Instance is stopping.",
-			LaunchInstanceResult.CommunicationError       => "Communication error.",
 			_                                             => "Unknown error."
 		};
 	}

Common/Phantom.Common.Data/Replies/SendCommandToInstanceResult.cs

@@ -2,20 +2,14 @@
 
 public enum SendCommandToInstanceResult {
 	Success,
-	InstanceDoesNotExist,
-	AgentShuttingDown,
-	AgentCommunicationError,
 	UnknownError
 }
 
 public static class SendCommandToInstanceResultExtensions {
 	public static string ToSentence(this SendCommandToInstanceResult reason) {
 		return reason switch {
-			SendCommandToInstanceResult.Success                 => "Command sent.",
-			SendCommandToInstanceResult.InstanceDoesNotExist    => "Instance does not exist.",
-			SendCommandToInstanceResult.AgentShuttingDown       => "Agent is shutting down.",
-			SendCommandToInstanceResult.AgentCommunicationError => "Agent did not reply in time.",
-			_                                                   => "Unknown error."
+			SendCommandToInstanceResult.Success => "Command sent.",
+			_                                   => "Unknown error."
 		};
 	}
 }

Common/Phantom.Common.Data/Replies/StopInstanceResult.cs

@@ -2,11 +2,8 @@
 
 public enum StopInstanceResult {
 	StopInitiated,
-	AgentShuttingDown,
-	InstanceDoesNotExist,
 	InstanceAlreadyStopping,
 	InstanceAlreadyStopped,
-	CommunicationError,
 	UnknownError
 }
 
@@ -14,11 +11,8 @@ public static class StopInstanceResultExtensions {
 	public static string ToSentence(this StopInstanceResult reason) {
 		return reason switch {
 			StopInstanceResult.StopInitiated           => "Stopping initiated.",
-			StopInstanceResult.AgentShuttingDown       => "Agent is shutting down.",
-			StopInstanceResult.InstanceDoesNotExist    => "Instance does not exist.",
 			StopInstanceResult.InstanceAlreadyStopping => "Instance is already stopping.",
 			StopInstanceResult.InstanceAlreadyStopped  => "Instance is already stopped.",
-			StopInstanceResult.CommunicationError      => "Communication error.",
 			_                                          => "Unknown error."
 		};
 	}

Common/Phantom.Common.Logging/Phantom.Common.Logging.csproj

@@ -7,8 +7,8 @@
   </PropertyGroup>
   
   <ItemGroup>
-    <PackageReference Include="Serilog" Version="2.12.0" />
-    <PackageReference Include="Serilog.Sinks.Console" Version="4.1.0" />
+    <PackageReference Include="Serilog" />
+    <PackageReference Include="Serilog.Sinks.Console" />
   </ItemGroup>
 
 </Project>

Common/Phantom.Common.Messages/BiDirectional/ReplyMessage.cs

@@ -0,0 +1,18 @@
+using MemoryPack;
+using Phantom.Utils.Rpc.Message;
+
+namespace Phantom.Common.Messages.ToServer;
+
+[MemoryPackable]
+public sealed partial record ReplyMessage(
+	[property: MemoryPackOrder(0)] uint SequenceId,
+	[property: MemoryPackOrder(1)] byte[] SerializedReply
+) : IMessageToServer, IMessageToAgent {
+	public Task<NoReply> Accept(IMessageToServerListener listener) {
+		return listener.HandleReply(this);
+	}
+
+	public Task<NoReply> Accept(IMessageToAgentListener listener) {
+		return listener.HandleReply(this);
+	}
+}

Common/Phantom.Common.Messages/IMessageToAgent.cs

@@ -2,4 +2,8 @@
 
 namespace Phantom.Common.Messages;
 
-public interface IMessageToAgent : IMessage<IMessageToAgentListener> {}
+public interface IMessageToAgent<TReply> : IMessage<IMessageToAgentListener, TReply> {}
+
+public interface IMessageToAgent : IMessageToAgent<NoReply> {
+	uint IMessage<IMessageToAgentListener, NoReply>.SequenceId => 0;
+}

Common/Phantom.Common.Messages/IMessageToAgentListener.cs

@@ -1,13 +1,16 @@
-using Phantom.Common.Messages.ToAgent;
+using Phantom.Common.Data.Replies;
+using Phantom.Common.Messages.ToAgent;
+using Phantom.Common.Messages.ToServer;
+using Phantom.Utils.Rpc.Message;
 
 namespace Phantom.Common.Messages;
 
 public interface IMessageToAgentListener {
-	Task HandleRegisterAgentSuccessResult(RegisterAgentSuccessMessage message);
-	Task HandleRegisterAgentFailureResult(RegisterAgentFailureMessage message);
-	Task HandleConfigureInstance(ConfigureInstanceMessage message);
-	Task HandleLaunchInstance(LaunchInstanceMessage message);
-	Task HandleStopInstance(StopInstanceMessage message);
-	Task HandleSendCommandToInstance(SendCommandToInstanceMessage message);
-	Task HandleShutdownAgent(ShutdownAgentMessage message);
+	Task<NoReply> HandleRegisterAgentSuccess(RegisterAgentSuccessMessage message);
+	Task<NoReply> HandleRegisterAgentFailure(RegisterAgentFailureMessage message);
+	Task<InstanceActionResult<ConfigureInstanceResult>> HandleConfigureInstance(ConfigureInstanceMessage message);
+	Task<InstanceActionResult<LaunchInstanceResult>> HandleLaunchInstance(LaunchInstanceMessage message);
+	Task<InstanceActionResult<StopInstanceResult>> HandleStopInstance(StopInstanceMessage message);
+	Task<InstanceActionResult<SendCommandToInstanceResult>> HandleSendCommandToInstance(SendCommandToInstanceMessage message);
+	Task<NoReply> HandleReply(ReplyMessage message);
 }

Common/Phantom.Common.Messages/IMessageToServer.cs

@@ -2,4 +2,8 @@
 
 namespace Phantom.Common.Messages; 
 
-public interface IMessageToServer : IMessage<IMessageToServerListener> {}
+public interface IMessageToServer<TReply> : IMessage<IMessageToServerListener, TReply> {}
+
+public interface IMessageToServer : IMessageToServer<NoReply> {
+	uint IMessage<IMessageToServerListener, NoReply>.SequenceId => 0;
+}

Common/Phantom.Common.Messages/IMessageToServerListener.cs

@@ -1,14 +1,15 @@
 using Phantom.Common.Messages.ToServer;
+using Phantom.Utils.Rpc.Message;
 
 namespace Phantom.Common.Messages; 
 
 public interface IMessageToServerListener {
 	bool IsDisposed { get; }
-	Task HandleRegisterAgent(RegisterAgentMessage message);
-	Task HandleUnregisterAgent(UnregisterAgentMessage message);
-	Task HandleAgentIsAlive(AgentIsAliveMessage message);
-	Task HandleAdvertiseJavaRuntimes(AdvertiseJavaRuntimesMessage message);
-	Task HandleReportInstanceStatus(ReportInstanceStatusMessage message);
-	Task HandleInstanceOutput(InstanceOutputMessage message);
-	Task HandleSimpleReply(SimpleReplyMessage message);
+	Task<NoReply> HandleRegisterAgent(RegisterAgentMessage message);
+	Task<NoReply> HandleUnregisterAgent(UnregisterAgentMessage message);
+	Task<NoReply> HandleAgentIsAlive(AgentIsAliveMessage message);
+	Task<NoReply> HandleAdvertiseJavaRuntimes(AdvertiseJavaRuntimesMessage message);
+	Task<NoReply> HandleReportInstanceStatus(ReportInstanceStatusMessage message);
+	Task<NoReply> HandleInstanceOutput(InstanceOutputMessage message);
+	Task<NoReply> HandleReply(ReplyMessage message);
 }

Common/Phantom.Common.Messages/IMessageWithReply.cs

@@ -1,5 +0,0 @@
-namespace Phantom.Common.Messages;
-
-public interface IMessageWithReply {
-	public uint SequenceId { get; }
-}

Common/Phantom.Common.Messages/MessageRegistries.cs

@@ -1,4 +1,5 @@
-using Phantom.Common.Logging;
+using Phantom.Common.Data.Replies;
+using Phantom.Common.Logging;
 using Phantom.Common.Messages.ToAgent;
 using Phantom.Common.Messages.ToServer;
 using Phantom.Utils.Rpc.Message;
@@ -6,24 +7,24 @@ using Phantom.Utils.Rpc.Message;
 namespace Phantom.Common.Messages; 
 
 public static class MessageRegistries {
-	public static MessageRegistry<IMessageToAgentListener, IMessageToAgent> ToAgent { get; } = new (PhantomLogger.Create("MessageRegistry:ToAgent"));
-	public static MessageRegistry<IMessageToServerListener, IMessageToServer> ToServer { get; } = new (PhantomLogger.Create("MessageRegistry:ToServer"));
+	public static MessageRegistry<IMessageToAgentListener> ToAgent { get; } = new (PhantomLogger.Create("MessageRegistry:ToAgent"));
+	public static MessageRegistry<IMessageToServerListener> ToServer { get; } = new (PhantomLogger.Create("MessageRegistry:ToServer"));
 
 	static MessageRegistries() {
-		ToAgent.Add<RegisterAgentSuccessMessage>(0);
-		ToAgent.Add<RegisterAgentFailureMessage>(1);
-		ToAgent.Add<ConfigureInstanceMessage>(2);
-		ToAgent.Add<LaunchInstanceMessage>(3);
-		ToAgent.Add<StopInstanceMessage>(4);
-		ToAgent.Add<SendCommandToInstanceMessage>(5);
-		ToAgent.Add<ShutdownAgentMessage>(6);
+		ToAgent.Add<RegisterAgentSuccessMessage, NoReply>(0);
+		ToAgent.Add<RegisterAgentFailureMessage, NoReply>(1);
+		ToAgent.Add<ConfigureInstanceMessage, InstanceActionResult<ConfigureInstanceResult>>(2);
+		ToAgent.Add<LaunchInstanceMessage, InstanceActionResult<LaunchInstanceResult>>(3);
+		ToAgent.Add<StopInstanceMessage, InstanceActionResult<StopInstanceResult>>(4);
+		ToAgent.Add<SendCommandToInstanceMessage, InstanceActionResult<SendCommandToInstanceResult>>(5);
+		ToAgent.Add<ReplyMessage, NoReply>(127);
 		
-		ToServer.Add<RegisterAgentMessage>(0);
-		ToServer.Add<UnregisterAgentMessage>(1);
-		ToServer.Add<AgentIsAliveMessage>(2);
-		ToServer.Add<AdvertiseJavaRuntimesMessage>(3);
-		ToServer.Add<ReportInstanceStatusMessage>(4);
-		ToServer.Add<InstanceOutputMessage>(5);
-		ToServer.Add<SimpleReplyMessage>(127);
+		ToServer.Add<RegisterAgentMessage, NoReply>(0);
+		ToServer.Add<UnregisterAgentMessage, NoReply>(1);
+		ToServer.Add<AgentIsAliveMessage, NoReply>(2);
+		ToServer.Add<AdvertiseJavaRuntimesMessage, NoReply>(3);
+		ToServer.Add<ReportInstanceStatusMessage, NoReply>(4);
+		ToServer.Add<InstanceOutputMessage, NoReply>(5);
+		ToServer.Add<ReplyMessage, NoReply>(127);
 	}
 }

Common/Phantom.Common.Messages/ToAgent/ConfigureInstanceMessage.cs

@@ -1,14 +1,15 @@
-using MessagePack;
+using MemoryPack;
 using Phantom.Common.Data.Instance;
+using Phantom.Common.Data.Replies;
 
 namespace Phantom.Common.Messages.ToAgent;
 
-[MessagePackObject]
-public sealed record ConfigureInstanceMessage(
-	[property: Key(0)] uint SequenceId,
-	[property: Key(1)] InstanceConfiguration Configuration
-) : IMessageToAgent, IMessageWithReply {
-	public Task Accept(IMessageToAgentListener listener) {
+[MemoryPackable]
+public sealed partial record ConfigureInstanceMessage(
+	[property: MemoryPackOrder(0)] uint SequenceId,
+	[property: MemoryPackOrder(1)] InstanceConfiguration Configuration
+) : IMessageToAgent<InstanceActionResult<ConfigureInstanceResult>> {
+	public Task<InstanceActionResult<ConfigureInstanceResult>> Accept(IMessageToAgentListener listener) {
 		return listener.HandleConfigureInstance(this);
 	}
 }

Common/Phantom.Common.Messages/ToAgent/LaunchInstanceMessage.cs

@@ -1,13 +1,14 @@
-using MessagePack;
+using MemoryPack;
+using Phantom.Common.Data.Replies;
 
 namespace Phantom.Common.Messages.ToAgent; 
 
-[MessagePackObject]
-public sealed record LaunchInstanceMessage(
-	[property: Key(0)] uint SequenceId,
-	[property: Key(1)] Guid InstanceGuid
-) : IMessageToAgent, IMessageWithReply {
-	public Task Accept(IMessageToAgentListener listener) {
+[MemoryPackable]
+public sealed partial record LaunchInstanceMessage(
+	[property: MemoryPackOrder(0)] uint SequenceId,
+	[property: MemoryPackOrder(1)] Guid InstanceGuid
+) : IMessageToAgent<InstanceActionResult<LaunchInstanceResult>> {
+	public Task<InstanceActionResult<LaunchInstanceResult>> Accept(IMessageToAgentListener listener) {
 		return listener.HandleLaunchInstance(this);
 	}
 }

Common/Phantom.Common.Messages/ToAgent/RegisterAgentFailureMessage.cs

@@ -1,13 +1,14 @@
-using MessagePack;
+using MemoryPack;
 using Phantom.Common.Data.Replies;
+using Phantom.Utils.Rpc.Message;
 
 namespace Phantom.Common.Messages.ToAgent;
 
-[MessagePackObject]
-public sealed record RegisterAgentFailureMessage(
-	[property: Key(0)] RegisterAgentFailure FailureKind
+[MemoryPackable]
+public sealed partial record RegisterAgentFailureMessage(
+	[property: MemoryPackOrder(0)] RegisterAgentFailure FailureKind
 ) : IMessageToAgent {
-	public Task Accept(IMessageToAgentListener listener) {
-		return listener.HandleRegisterAgentFailureResult(this);
+	public Task<NoReply> Accept(IMessageToAgentListener listener) {
+		return listener.HandleRegisterAgentFailure(this);
 	}
 }

Common/Phantom.Common.Messages/ToAgent/RegisterAgentSuccessMessage.cs

@@ -1,14 +1,15 @@
 using System.Collections.Immutable;
-using MessagePack;
+using MemoryPack;
 using Phantom.Common.Data.Instance;
+using Phantom.Utils.Rpc.Message;
 
 namespace Phantom.Common.Messages.ToAgent;
 
-[MessagePackObject]
-public sealed record RegisterAgentSuccessMessage(
-	[property: Key(0)] ImmutableArray<InstanceConfiguration> InitialInstances
+[MemoryPackable]
+public sealed partial record RegisterAgentSuccessMessage(
+	[property: MemoryPackOrder(0)] ImmutableArray<InstanceConfiguration> InitialInstances
 ) : IMessageToAgent {
-	public Task Accept(IMessageToAgentListener listener) {
-		return listener.HandleRegisterAgentSuccessResult(this);
+	public Task<NoReply> Accept(IMessageToAgentListener listener) {
+		return listener.HandleRegisterAgentSuccess(this);
 	}
 }

Common/Phantom.Common.Messages/ToAgent/SendCommandToInstanceMessage.cs

@@ -1,14 +1,15 @@
-using MessagePack;
+using MemoryPack;
+using Phantom.Common.Data.Replies;
 
 namespace Phantom.Common.Messages.ToAgent; 
 
-[MessagePackObject]
-public sealed record SendCommandToInstanceMessage(
-	[property: Key(0)] uint SequenceId,
-	[property: Key(1)] Guid InstanceGuid,
-	[property: Key(2)] string Command
-) : IMessageToAgent, IMessageWithReply {
-	public Task Accept(IMessageToAgentListener listener) {
+[MemoryPackable]
+public sealed partial record SendCommandToInstanceMessage(
+	[property: MemoryPackOrder(0)] uint SequenceId,
+	[property: MemoryPackOrder(1)] Guid InstanceGuid,
+	[property: MemoryPackOrder(2)] string Command
+) : IMessageToAgent<InstanceActionResult<SendCommandToInstanceResult>> {
+	public Task<InstanceActionResult<SendCommandToInstanceResult>> Accept(IMessageToAgentListener listener) {
 		return listener.HandleSendCommandToInstance(this);
 	}
 }

Common/Phantom.Common.Messages/ToAgent/ShutdownAgentMessage.cs

@@ -1,10 +0,0 @@
-using MessagePack;
-
-namespace Phantom.Common.Messages.ToAgent; 
-
-[MessagePackObject]
-public sealed record ShutdownAgentMessage : IMessageToAgent {
-	public Task Accept(IMessageToAgentListener listener) {
-		return listener.HandleShutdownAgent(this);
-	}
-}

Common/Phantom.Common.Messages/ToAgent/StopInstanceMessage.cs

@@ -1,13 +1,16 @@
-using MessagePack;
+using MemoryPack;
+using Phantom.Common.Data.Minecraft;
+using Phantom.Common.Data.Replies;
 
 namespace Phantom.Common.Messages.ToAgent; 
 
-[MessagePackObject]
-public sealed record StopInstanceMessage(
-	[property: Key(0)] uint SequenceId,
-	[property: Key(1)] Guid InstanceGuid
-) : IMessageToAgent, IMessageWithReply {
-	public Task Accept(IMessageToAgentListener listener) {
+[MemoryPackable]
+public sealed partial record StopInstanceMessage(
+	[property: MemoryPackOrder(0)] uint SequenceId,
+	[property: MemoryPackOrder(1)] Guid InstanceGuid,
+	[property: MemoryPackOrder(2)] MinecraftStopStrategy StopStrategy
+) : IMessageToAgent<InstanceActionResult<StopInstanceResult>> {
+	public Task<InstanceActionResult<StopInstanceResult>> Accept(IMessageToAgentListener listener) {
 		return listener.HandleStopInstance(this);
 	}
 }

Common/Phantom.Common.Messages/ToServer/AdvertiseJavaRuntimesMessage.cs

@@ -1,14 +1,15 @@
 using System.Collections.Immutable;
-using MessagePack;
+using MemoryPack;
 using Phantom.Common.Data.Java;
+using Phantom.Utils.Rpc.Message;
 
 namespace Phantom.Common.Messages.ToServer; 
 
-[MessagePackObject]
-public sealed record AdvertiseJavaRuntimesMessage(
-	[property: Key(0)] ImmutableArray<TaggedJavaRuntime> Runtimes
+[MemoryPackable]
+public sealed partial record AdvertiseJavaRuntimesMessage(
+	[property: MemoryPackOrder(0)] ImmutableArray<TaggedJavaRuntime> Runtimes
 ) : IMessageToServer {
-	public Task Accept(IMessageToServerListener listener) {
+	public Task<NoReply> Accept(IMessageToServerListener listener) {
 		return listener.HandleAdvertiseJavaRuntimes(this);
 	}
 }

Common/Phantom.Common.Messages/ToServer/AgentIsAliveMessage.cs

@@ -1,10 +1,11 @@
-using MessagePack;
+using MemoryPack;
+using Phantom.Utils.Rpc.Message;
 
 namespace Phantom.Common.Messages.ToServer; 
 
-[MessagePackObject]
-public sealed record AgentIsAliveMessage : IMessageToServer {
-	public Task Accept(IMessageToServerListener listener) {
+[MemoryPackable]
+public sealed partial record AgentIsAliveMessage : IMessageToServer {
+	public Task<NoReply> Accept(IMessageToServerListener listener) {
 		return listener.HandleAgentIsAlive(this);
 	}
 }

Common/Phantom.Common.Messages/ToServer/InstanceOutputMessage.cs

@@ -1,14 +1,15 @@
 using System.Collections.Immutable;
-using MessagePack;
+using MemoryPack;
+using Phantom.Utils.Rpc.Message;
 
 namespace Phantom.Common.Messages.ToServer;
 
-[MessagePackObject]
-public sealed record InstanceOutputMessage(
-	[property: Key(0)] Guid InstanceGuid,
-	[property: Key(1)] ImmutableArray<string> Lines
+[MemoryPackable]
+public sealed partial record InstanceOutputMessage(
+	[property: MemoryPackOrder(0)] Guid InstanceGuid,
+	[property: MemoryPackOrder(1)] ImmutableArray<string> Lines
 ) : IMessageToServer {
-	public Task Accept(IMessageToServerListener listener) {
+	public Task<NoReply> Accept(IMessageToServerListener listener) {
 		return listener.HandleInstanceOutput(this);
 	}
 }

Common/Phantom.Common.Messages/ToServer/RegisterAgentMessage.cs

@@ -1,14 +1,15 @@
-using MessagePack;
+using MemoryPack;
 using Phantom.Common.Data.Agent;
+using Phantom.Utils.Rpc.Message;
 
 namespace Phantom.Common.Messages.ToServer;
 
-[MessagePackObject]
-public sealed record RegisterAgentMessage(
-	[property: Key(0)] AgentAuthToken AuthToken,
-	[property: Key(1)] AgentInfo AgentInfo
+[MemoryPackable]
+public sealed partial record RegisterAgentMessage(
+	[property: MemoryPackOrder(0)] AgentAuthToken AuthToken,
+	[property: MemoryPackOrder(1)] AgentInfo AgentInfo
 ) : IMessageToServer {
-	public Task Accept(IMessageToServerListener listener) {
+	public Task<NoReply> Accept(IMessageToServerListener listener) {
 		return listener.HandleRegisterAgent(this);
 	}
 }

Common/Phantom.Common.Messages/ToServer/ReportInstanceStatusMessage.cs

@@ -1,14 +1,15 @@
-using MessagePack;
+using MemoryPack;
 using Phantom.Common.Data.Instance;
+using Phantom.Utils.Rpc.Message;
 
 namespace Phantom.Common.Messages.ToServer;
 
-[MessagePackObject]
-public sealed record ReportInstanceStatusMessage(
-	[property: Key(0)] Guid InstanceGuid,
-	[property: Key(1)] InstanceStatus InstanceStatus
+[MemoryPackable]
+public sealed partial record ReportInstanceStatusMessage(
+	[property: MemoryPackOrder(0)] Guid InstanceGuid,
+	[property: MemoryPackOrder(1)] IInstanceStatus InstanceStatus
 ) : IMessageToServer {
-	public Task Accept(IMessageToServerListener listener) {
+	public Task<NoReply> Accept(IMessageToServerListener listener) {
 		return listener.HandleReportInstanceStatus(this);
 	}
 }

Common/Phantom.Common.Messages/ToServer/SimpleReplyMessage.cs

@@ -1,22 +0,0 @@
-using System.Runtime.CompilerServices;
-using MessagePack;
-
-namespace Phantom.Common.Messages.ToServer;
-
-[MessagePackObject]
-public sealed record SimpleReplyMessage(
-	[property: Key(0)] uint SequenceId,
-	[property: Key(1)] int EnumValue
-) : IMessageToServer {
-	public static SimpleReplyMessage FromEnum<TEnum>(uint sequenceId, TEnum enumValue) where TEnum : Enum {
-		if (Unsafe.SizeOf<TEnum>() != Unsafe.SizeOf<int>()) {
-			throw new ArgumentException("Enum type " + typeof(TEnum).Name + " is not compatible with int.", nameof(TEnum));
-		}
-
-		return new SimpleReplyMessage(sequenceId, Unsafe.As<TEnum, int>(ref enumValue));
-	}
-
-	public Task Accept(IMessageToServerListener listener) {
-		return listener.HandleSimpleReply(this);
-	}
-}

Common/Phantom.Common.Messages/ToServer/UnregisterAgentMessage.cs

@@ -1,12 +1,13 @@
-using MessagePack;
+using MemoryPack;
+using Phantom.Utils.Rpc.Message;
 
 namespace Phantom.Common.Messages.ToServer;
 
-[MessagePackObject]
-public sealed record UnregisterAgentMessage(
-	[property: Key(0)] Guid AgentGuid
+[MemoryPackable]
+public sealed partial record UnregisterAgentMessage(
+	[property: MemoryPackOrder(0)] Guid AgentGuid
 ) : IMessageToServer {
-	public Task Accept(IMessageToServerListener listener) {
+	public Task<NoReply> Accept(IMessageToServerListener listener) {
 		return listener.HandleUnregisterAgent(this);
 	}
 }

Common/Phantom.Common.Minecraft/JvmArgumentsHelper.cs

@@ -0,0 +1,49 @@
+using System.Collections.Immutable;
+
+namespace Phantom.Common.Minecraft;
+
+public static class JvmArgumentsHelper {
+	public static ImmutableArray<string> Split(string arguments) {
+		return arguments.Split('\n', StringSplitOptions.TrimEntries | StringSplitOptions.RemoveEmptyEntries).ToImmutableArray();
+	}
+
+	public static ValidationError? Validate(string arguments) {
+		return Validate(Split(arguments));
+	}
+	
+	public static ValidationError? Validate(ImmutableArray<string> arguments) {
+		if (!arguments.All(static argument => argument.StartsWith('-'))) {
+			return ValidationError.InvalidFormat;
+		}
+
+		// TODO not perfect, but good enough
+		if (arguments.Any(static argument => argument.Contains("-Xmx"))) {
+			return ValidationError.XmxNotAllowed;
+		}
+		
+		if (arguments.Any(static argument => argument.Contains("-Xms"))) {
+			return ValidationError.XmsNotAllowed;
+		}
+		
+		return null;
+	}
+
+	public static string Join(ImmutableArray<string> arguments) {
+		return string.Join('\n', arguments);
+	}
+
+	public enum ValidationError {
+		InvalidFormat,
+		XmxNotAllowed,
+		XmsNotAllowed
+	}
+
+	public static string ToSentence(this ValidationError? result) {
+		return result switch {
+			ValidationError.InvalidFormat => "Invalid format.",
+			ValidationError.XmxNotAllowed => "The -Xmx argument must not be specified manually.",
+			ValidationError.XmsNotAllowed => "The -Xms argument must not be specified manually.",
+			_                             => throw new ArgumentOutOfRangeException(nameof(result), result, null)
+		};
+	}
+}

Common/Phantom.Common.Minecraft/MinecraftServerExecutableInfo.cs

@@ -1,9 +1,9 @@
 using Phantom.Utils.Cryptography;
 using Phantom.Utils.IO;
 
-namespace Phantom.Agent.Minecraft.Server; 
+namespace Phantom.Common.Minecraft; 
 
-sealed record ServerExecutableInfo(
+public sealed record MinecraftServerExecutableInfo(
 	string DownloadUrl,
 	Sha1String Hash,
 	FileSize Size

Common/Phantom.Common.Minecraft/MinecraftVersions.cs

@@ -0,0 +1,201 @@
+using System.Collections.Immutable;
+using System.Diagnostics;
+using System.Net.Http.Json;
+using System.Text.Json;
+using Phantom.Common.Data.Minecraft;
+using Phantom.Common.Logging;
+using Phantom.Utils.Cryptography;
+using Phantom.Utils.IO;
+using Phantom.Utils.Runtime;
+using Serilog;
+
+namespace Phantom.Common.Minecraft;
+
+public sealed class MinecraftVersions : IDisposable {
+	private static readonly ILogger Logger = PhantomLogger.Create<MinecraftVersions>();
+	private static readonly TimeSpan CacheRetentionTime = TimeSpan.FromMinutes(10);
+
+	private const string VersionManifestUrl = "https://launchermeta.mojang.com/mc/game/version_manifest.json";
+
+	private readonly HttpClient http = new ();
+
+	private readonly Stopwatch cacheTimer = new ();
+	private readonly SemaphoreSlim cachedVersionsSemaphore = new (1, 1);
+
+	private ImmutableArray<MinecraftVersion>? cachedVersions;
+	private ImmutableArray<MinecraftVersion>? CachedVersionsUnlessExpired => cacheTimer.IsRunning && cacheTimer.Elapsed < CacheRetentionTime ? cachedVersions : null;
+
+	public void Dispose() {
+		http.Dispose();
+		cachedVersionsSemaphore.Dispose();
+	}
+
+	public async Task<ImmutableArray<MinecraftVersion>> GetVersions(CancellationToken cancellationToken) {
+		if (CachedVersionsUnlessExpired is {} earlyResult) {
+			return earlyResult;
+		}
+
+		try {
+			await cachedVersionsSemaphore.WaitAsync(cancellationToken);
+		} catch (OperationCanceledException) {
+			return ImmutableArray<MinecraftVersion>.Empty;
+		}
+
+		try {
+			if (CachedVersionsUnlessExpired is {} racedResult) {
+				return racedResult;
+			}
+
+			ImmutableArray<MinecraftVersion> versions = await FetchVersions(cancellationToken) ?? ImmutableArray<MinecraftVersion>.Empty;
+			Logger.Information("Refreshed Minecraft version cache, {Versions} version(s) found.", versions.Length);
+			
+			cachedVersions = versions;
+			cacheTimer.Restart();
+			return versions;
+		} finally {
+			cachedVersionsSemaphore.Release();
+		}
+	}
+
+	private async Task<ImmutableArray<MinecraftVersion>?> FetchVersions(CancellationToken cancellationToken) {
+		return await FetchOrFailSilently(async () => {
+			var versionManifest = await FetchJson(http, VersionManifestUrl, "version manifest", cancellationToken);
+			return GetVersionsFromManifest(versionManifest);
+		});
+	}
+
+	public async Task<MinecraftServerExecutableInfo?> GetServerExecutableInfo(string version, CancellationToken cancellationToken) {
+		return await FetchOrFailSilently(async () => {
+			var versions = await GetVersions(cancellationToken);
+			var versionObject = versions.FirstOrDefault(v => v.Id == version);
+			if (versionObject == null) {
+				Logger.Error("Version {Version} was not found in version manifest.", version);
+				return null;
+			}
+
+			var versionMetadata = await FetchJson(http, versionObject.MetadataUrl, "version metadata", cancellationToken);
+			return GetServerExecutableInfoFromMetadata(versionMetadata);
+		});
+	}
+
+	private static async Task<T?> FetchOrFailSilently<T>(Func<Task<T?>> task) {
+		try {
+			return await task();
+		} catch (OperationCanceledException) {
+			return default;
+		} catch (StopProcedureException) {
+			return default;
+		} catch (Exception e) {
+			Logger.Error(e, "An unexpected error occurred.");
+			return default;
+		}
+	}
+
+	private static async Task<JsonElement> FetchJson(HttpClient http, string url, string description, CancellationToken cancellationToken) {
+		Logger.Information("Fetching {Description} JSON from: {Url}", description, url);
+
+		try {
+			return await http.GetFromJsonAsync<JsonElement>(url, cancellationToken);
+		} catch (OperationCanceledException) {
+			throw StopProcedureException.Instance;
+		}  catch (HttpRequestException e) {
+			Logger.Error(e, "Unable to download {Description}.", description);
+			throw StopProcedureException.Instance;
+		} catch (Exception e) {
+			Logger.Error(e, "Unable to parse {Description} as JSON.", description);
+			throw StopProcedureException.Instance;
+		}
+	}
+
+	private static ImmutableArray<MinecraftVersion> GetVersionsFromManifest(JsonElement versionManifest) {
+		JsonElement versionsElement = GetJsonPropertyOrThrow(versionManifest, "versions", JsonValueKind.Array, "version manifest");
+		var foundVersions = ImmutableArray.CreateBuilder<MinecraftVersion>(versionsElement.GetArrayLength());
+
+		foreach (var versionElement in versionsElement.EnumerateArray()) {
+			try {
+				foundVersions.Add(GetVersionFromManifestEntry(versionElement));
+			} catch (StopProcedureException) {}
+		}
+
+		return foundVersions.ToImmutable();
+	}
+
+	private static MinecraftVersion GetVersionFromManifestEntry(JsonElement versionElement) {
+		JsonElement idElement = GetJsonPropertyOrThrow(versionElement, "id", JsonValueKind.String, "version entry in version manifest");
+		string id = idElement.GetString() ?? throw new InvalidOperationException();
+
+		JsonElement typeElement = GetJsonPropertyOrThrow(versionElement, "type", JsonValueKind.String, "version entry in version manifest");
+		string? typeString = typeElement.GetString();
+
+		var type = MinecraftVersionTypes.FromString(typeString);
+		if (type == MinecraftVersionType.Other) {
+			Logger.Verbose("Unknown version type: {Type} ({Version})", typeString, id);
+		}
+
+		JsonElement urlElement = GetJsonPropertyOrThrow(versionElement, "url", JsonValueKind.String, "version entry in version manifest");
+		string? url = urlElement.GetString();
+
+		if (!Uri.TryCreate(url, UriKind.Absolute, out var uri)) {
+			Logger.Error("The \"url\" key in version entry in version manifest does not contain a valid URL: {Url}", url);
+			throw StopProcedureException.Instance;
+		}
+
+		if (uri.Scheme != "https" || !uri.AbsolutePath.EndsWith(".json", StringComparison.OrdinalIgnoreCase)) {
+			Logger.Error("The \"url\" key in version entry in version manifest does not contain an accepted URL: {Url}", url);
+			throw StopProcedureException.Instance;
+		}
+
+		return new MinecraftVersion(id, type, url);
+	}
+
+	private static MinecraftServerExecutableInfo GetServerExecutableInfoFromMetadata(JsonElement versionMetadata) {
+		JsonElement downloadsElement = GetJsonPropertyOrThrow(versionMetadata, "downloads", JsonValueKind.Object, "version metadata");
+		JsonElement serverElement = GetJsonPropertyOrThrow(downloadsElement, "server", JsonValueKind.Object, "downloads object in version metadata");
+		JsonElement urlElement = GetJsonPropertyOrThrow(serverElement, "url", JsonValueKind.String, "downloads.server object in version metadata");
+		string? url = urlElement.GetString();
+
+		if (!Uri.TryCreate(url, UriKind.Absolute, out var uri)) {
+			Logger.Error("The \"url\" key in downloads.server object in version metadata does not contain a valid URL: {Url}", url);
+			throw StopProcedureException.Instance;
+		}
+
+		if (uri.Scheme != "https" || !uri.AbsolutePath.EndsWith(".jar", StringComparison.OrdinalIgnoreCase)) {
+			Logger.Error("The \"url\" key in downloads.server object in version metadata does not contain a accepted URL: {Url}", url);
+			throw StopProcedureException.Instance;
+		}
+
+		JsonElement sizeElement = GetJsonPropertyOrThrow(serverElement, "size", JsonValueKind.Number, "downloads.server object in version metadata");
+		ulong size;
+		try {
+			size = sizeElement.GetUInt64();
+		} catch (FormatException) {
+			Logger.Error("The \"size\" key in downloads.server object in version metadata contains an invalid file size: {Size}", sizeElement);
+			throw StopProcedureException.Instance;
+		}
+
+		JsonElement sha1Element = GetJsonPropertyOrThrow(serverElement, "sha1", JsonValueKind.String, "downloads.server object in version metadata");
+		Sha1String hash;
+		try {
+			hash = Sha1String.FromString(sha1Element.GetString());
+		} catch (Exception) {
+			Logger.Error("The \"sha1\" key in downloads.server object in version metadata does not contain a valid SHA-1 hash: {Sha1}", sha1Element.GetString());
+			throw StopProcedureException.Instance;
+		}
+
+		return new MinecraftServerExecutableInfo(url, hash, new FileSize(size));
+	}
+
+	private static JsonElement GetJsonPropertyOrThrow(JsonElement parentElement, string propertyKey, JsonValueKind expectedKind, string location) {
+		if (!parentElement.TryGetProperty(propertyKey, out var valueElement)) {
+			Logger.Error("Missing \"{Property}\" key in " + location + ".", propertyKey);
+			throw StopProcedureException.Instance;
+		}
+
+		if (valueElement.ValueKind != expectedKind) {
+			Logger.Error("The \"{Property}\" key in " + location + " does not contain a JSON {ExpectedType}. Actual type: {ActualType}", propertyKey, expectedKind, valueElement.ValueKind);
+			throw StopProcedureException.Instance;
+		}
+
+		return valueElement;
+	}
+}