Initial port

MinecraftClient/Client.cs

@@ -0,0 +1,70 @@
+using System;
+using System.Net.Sockets;
+using System.Threading;
+
+namespace MinecraftClient
+{
+	public class MinecraftClient : IDisposable
+	{
+		private const int MaxMessageSize = 4110; // 4096 + 14 bytes of header data.
+
+		private TcpClient client;
+		private NetworkStream conn;
+		private int lastID = 0;
+
+		public MinecraftClient(string host, int port)
+		{
+			client = new TcpClient(host, port);
+			conn = client.GetStream();
+		}
+		
+		public void Dispose()
+		{
+		    this.Close();
+		}
+
+		public void Close()
+		{
+			conn.Close();
+			client.Close();
+		}
+
+		public bool Authenticate(string password)
+		{
+			Message resp;
+			return sendMessage(new Message(
+				password.Length + Encoder.HeaderLength,
+				Interlocked.Increment(ref lastID),
+				MessageType.Authenticate,
+				password
+			), out resp);
+		}
+
+		public bool SendCommand(string command, out Message resp)
+		{
+			return sendMessage(new Message(
+				command.Length + Encoder.HeaderLength,
+				Interlocked.Increment(ref lastID),
+				MessageType.Command,
+				command
+			), out resp);
+		}
+
+		private bool sendMessage(Message req, out Message resp)
+		{
+			// Send the message.
+			byte[] encoded = Encoder.EncodeMessage(req);
+			conn.Write(encoded, 0, encoded.Length);
+
+			// Receive the response.
+			byte[] respBytes = new byte[MaxMessageSize];
+			int bytesRead = conn.Read(respBytes, 0, respBytes.Length);
+			Array.Resize(ref respBytes, bytesRead);
+
+			// Decode the response and check for errors before returning.
+			resp = Encoder.DecodeMessage(respBytes);
+			if (req.ID != resp.ID) { return false; };
+			return true;
+		}
+	}
+}

MinecraftClient/MessageEncoder.cs

@@ -0,0 +1,65 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace MinecraftClient
+{
+	public enum MessageType : int
+	{
+		Response,
+		_,
+		Command,
+		Authenticate
+	}
+
+	public readonly struct Message
+	{
+		public readonly int Length;
+		public readonly int ID;
+		public readonly MessageType Type;
+		public readonly String Body;
+
+		public Message(int length, int id, MessageType type, String body)
+		{
+			Length = length;
+			ID = id;
+			Type = type;
+			Body = body;
+		}
+	}
+
+	public class Encoder
+	{
+		public const int HeaderLength = 10; // Does not include 4-byte message length.
+
+		public static byte[] EncodeMessage(Message msg)
+		{
+			List<byte> bytes = new List<byte>();
+
+			bytes.AddRange(BitConverter.GetBytes(msg.Length));
+			bytes.AddRange(BitConverter.GetBytes(msg.ID));
+			bytes.AddRange(BitConverter.GetBytes((int)msg.Type));
+			bytes.AddRange(Encoding.ASCII.GetBytes(msg.Body));
+			bytes.AddRange(new byte[] { 0, 0 });
+
+			return bytes.ToArray();
+		}
+
+		public static Message DecodeMessage(byte[] bytes)
+		{
+			int len = BitConverter.ToInt32(bytes, 0);
+			int id = BitConverter.ToInt32(bytes, 4);
+			int type = BitConverter.ToInt32(bytes, 8);
+
+			int bodyLen = bytes.Length - (HeaderLength + 4);
+			if (bodyLen > 0)
+			{
+				byte[] bodyBytes = new byte[bodyLen];
+				Array.Copy(bytes, 12, bodyBytes, 0, bodyLen);
+				Array.Resize(ref bodyBytes, bodyLen);
+				return new Message(len, id, (MessageType)type, Encoding.ASCII.GetString(bodyBytes));
+			}
+			else { return new Message(len, id, (MessageType)type, ""); }
+		}
+	}
+}

MinecraftClient/MinecraftClient.csproj

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+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net9.0</TargetFramework>
+  </PropertyGroup>
+
+</Project>

MinecraftClient/Shell.cs

@@ -0,0 +1,69 @@
+using System;
+using System.Collections.Generic;
+
+namespace MinecraftClient
+{
+	class Shell
+	{
+		private const string DefaultHost = "127.0.0.1";
+		private const int DefaultPort = 25575;
+		private const string DefaultPassword = "minecraft";
+
+		static void Main(string[] args)
+		{
+			string host = DefaultHost;
+			int port = DefaultPort;
+			string password = DefaultPassword;
+
+			// Parse arguments.
+			for (int i = 0; i < args.Length; i++)
+			{
+				switch (args[i])
+				{
+					case "--host":
+						host = args[i + 1];
+						break;
+					case "--port":
+						port = int.Parse(args[i + 1]);
+						break;
+					case "--password":
+						password = args[i + 1];
+						break;
+					default:
+						break;
+				}
+			}
+
+			// Connect and authenticate.
+			using (MinecraftClient client = new MinecraftClient(host, port))
+			{
+				if (!client.Authenticate(password))
+				{
+					Console.WriteLine("authentication failure");
+					return;
+				}
+
+				// Start RCON shell.
+				List<String> quitCommands = new List<String> { "exit", "quit" };
+				Console.WriteLine("Starting RCON shell. Use 'exit', 'quit', or Ctrl-C to exit.");
+				while (true)
+				{
+					Console.Write("> ");
+					String command = Console.ReadLine();
+					if (quitCommands.Contains(command)) { break; }
+
+					Message resp;
+					if (client.SendCommand(command, out resp))
+					{
+						Console.WriteLine(resp.Body);
+					}
+					else
+					{
+						Console.WriteLine("Error sending command.");
+						break;
+					}
+				}
+			}
+		}
+	}
+}