Added successful client connection flow.

client/src/main/java/nl/andrewl/aos2_client/Client.java

@@ -2,106 +2,101 @@ package nl.andrewl.aos2_client;
 
 import nl.andrewl.aos2_client.render.ChunkMesh;
 import nl.andrewl.aos2_client.render.ChunkRenderer;
-import nl.andrewl.aos2_client.render.WindowInfo;
+import nl.andrewl.aos2_client.render.WindowUtils;
 import nl.andrewl.aos_core.model.Chunk;
 import org.joml.Vector3i;
-import org.lwjgl.glfw.Callbacks;
-import org.lwjgl.glfw.GLFWErrorCallback;
-import org.lwjgl.opengl.GL;
 
+import java.io.IOException;
+import java.net.InetAddress;
+import java.net.UnknownHostException;
 import java.util.Random;
 
 import static org.lwjgl.glfw.GLFW.*;
 import static org.lwjgl.opengl.GL46.*;
 
-public class Client {
+public class Client implements Runnable {
-	public static void main(String[] args) {
+	public static void main(String[] args) throws IOException {
-		var windowInfo = initUI();
+		InetAddress serverAddress = InetAddress.getByName(args[0]);
-		long windowHandle = windowInfo.windowHandle();
+		int serverPort = Integer.parseInt(args[1]);
+		String username = args[2].trim();
 
-		Camera cam = new Camera();
+		Client client = new Client(serverAddress, serverPort, username);
-		cam.setOrientationDegrees(90, 90);
+		client.run();
-		cam.setPosition(-3, 3, 0);
-		glfwSetCursorPosCallback(windowHandle, cam);
 
-		Chunk chunk = Chunk.random(new Vector3i(0, 0, 0), new Random(1));
-		Chunk chunk2 = Chunk.random(new Vector3i(1, 0, 0), new Random(1));
-		Chunk chunk3 = Chunk.random(new Vector3i(1, 0, 1), new Random(1));
-		Chunk chunk4 = Chunk.random(new Vector3i(0, 0, 1), new Random(1));
 
-		chunk.setBlockAt(0, 0, 0, (byte) 0);
+//		var windowInfo = WindowUtils.initUI();
-
+//		long windowHandle = windowInfo.windowHandle();
-		for (int x = 0; x < Chunk.SIZE; x++) {
+//
-			for (int z = 0; z < Chunk.SIZE; z++) {
+//		Camera cam = new Camera();
-				chunk.setBlockAt(x, Chunk.SIZE - 1, z, (byte) 0);
+//		cam.setOrientationDegrees(90, 90);
-			}
+//		cam.setPosition(-3, 3, 0);
+//		glfwSetCursorPosCallback(windowHandle, cam);
+//
+//		Chunk chunk = Chunk.random(new Vector3i(0, 0, 0), new Random(1));
+//		Chunk chunk2 = Chunk.random(new Vector3i(1, 0, 0), new Random(1));
+//		Chunk chunk3 = Chunk.random(new Vector3i(1, 0, 1), new Random(1));
+//		Chunk chunk4 = Chunk.random(new Vector3i(0, 0, 1), new Random(1));
+//
+//		chunk.setBlockAt(0, 0, 0, (byte) 0);
+//
+//		for (int x = 0; x < Chunk.SIZE; x++) {
+//			for (int z = 0; z < Chunk.SIZE; z++) {
+//				chunk.setBlockAt(x, Chunk.SIZE - 1, z, (byte) 0);
+//			}
+//		}
+//
+//		ChunkRenderer chunkRenderer = new ChunkRenderer(windowInfo.width(), windowInfo.height());
+//		chunkRenderer.addChunkMesh(new ChunkMesh(chunk));
+//		chunkRenderer.addChunkMesh(new ChunkMesh(chunk2));
+//		chunkRenderer.addChunkMesh(new ChunkMesh(chunk3));
+//		chunkRenderer.addChunkMesh(new ChunkMesh(chunk4));
+//
+//		while (!glfwWindowShouldClose(windowHandle)) {
+//			glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+//
+//			chunkRenderer.draw(cam);
+//
+//			glfwSwapBuffers(windowHandle);
+//			glfwPollEvents();
+//
+//			if (glfwGetKey(windowHandle, GLFW_KEY_W) == GLFW_PRESS) cam.move(Camera.FORWARD);
+//			if (glfwGetKey(windowHandle, GLFW_KEY_S) == GLFW_PRESS) cam.move(Camera.BACKWARD);
+//			if (glfwGetKey(windowHandle, GLFW_KEY_A) == GLFW_PRESS) cam.move(Camera.LEFT);
+//			if (glfwGetKey(windowHandle, GLFW_KEY_D) == GLFW_PRESS) cam.move(Camera.RIGHT);
+//			if (glfwGetKey(windowHandle, GLFW_KEY_SPACE) == GLFW_PRESS) cam.move(Camera.UP);
+//			if (glfwGetKey(windowHandle, GLFW_KEY_LEFT_SHIFT) == GLFW_PRESS) cam.move(Camera.DOWN);
+//		}
+//
+//		chunkRenderer.free();
+//		WindowUtils.clearUI(windowHandle);
 	}
 
-		ChunkRenderer chunkRenderer = new ChunkRenderer(windowInfo.width(), windowInfo.height());
+	private InetAddress serverAddress;
-		chunkRenderer.addChunkMesh(new ChunkMesh(chunk));
+	private int serverPort;
-		chunkRenderer.addChunkMesh(new ChunkMesh(chunk2));
+	private String username;
-		chunkRenderer.addChunkMesh(new ChunkMesh(chunk3));
+	private CommunicationHandler communicationHandler;
-		chunkRenderer.addChunkMesh(new ChunkMesh(chunk4));
+	private volatile boolean running;
 
-		while (!glfwWindowShouldClose(windowHandle)) {
+	public Client(InetAddress serverAddress, int serverPort, String username) {
-			glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+		this.serverAddress = serverAddress;
-
+		this.serverPort = serverPort;
-			chunkRenderer.draw(cam);
+		this.username = username;
-
+		this.communicationHandler = new CommunicationHandler();
-			glfwSwapBuffers(windowHandle);
-			glfwPollEvents();
-
-			if (glfwGetKey(windowHandle, GLFW_KEY_W) == GLFW_PRESS) cam.move(Camera.FORWARD);
-			if (glfwGetKey(windowHandle, GLFW_KEY_S) == GLFW_PRESS) cam.move(Camera.BACKWARD);
-			if (glfwGetKey(windowHandle, GLFW_KEY_A) == GLFW_PRESS) cam.move(Camera.LEFT);
-			if (glfwGetKey(windowHandle, GLFW_KEY_D) == GLFW_PRESS) cam.move(Camera.RIGHT);
-			if (glfwGetKey(windowHandle, GLFW_KEY_SPACE) == GLFW_PRESS) cam.move(Camera.UP);
-			if (glfwGetKey(windowHandle, GLFW_KEY_LEFT_SHIFT) == GLFW_PRESS) cam.move(Camera.DOWN);
 	}
 
-		chunkRenderer.free();
+	@Override
-
+	public void run() {
-		Callbacks.glfwFreeCallbacks(windowHandle);
+		running = false;
-		glfwDestroyWindow(windowHandle);
+		try {
-		glfwTerminate();
+			communicationHandler.establishConnection(serverAddress, serverPort, username);
-		glfwSetErrorCallback(null).free();
+			System.out.println("Established connection to the server.");
+		} catch (IOException e) {
+			e.printStackTrace();
+			running = false;
 		}
-
+		while (running) {
-	private static WindowInfo initUI() {
+			// Do game stuff
-		GLFWErrorCallback.createPrint(System.err).set();
+			System.out.println("Running!");
-		if (!glfwInit()) throw new IllegalStateException("Could not initialize GLFW.");
-		glfwDefaultWindowHints();
-		glfwWindowHint(GLFW_VISIBLE, GLFW_FALSE);
-		glfwWindowHint(GLFW_RESIZABLE, GLFW_FALSE);
-
-		var vidMode = glfwGetVideoMode(glfwGetPrimaryMonitor());
-		if (vidMode == null) throw new IllegalStateException("Could not get information about the primary monitory.");
-		long windowHandle = glfwCreateWindow(vidMode.width(), vidMode.height(), "Ace of Shades 2", glfwGetPrimaryMonitor(), 0);
-		if (windowHandle == 0) throw new RuntimeException("Failed to create GLFW window.");
-
-		glfwSetKeyCallback(windowHandle, (window, key, scancode, action, mods) -> {
-			if (key == GLFW_KEY_ESCAPE && action == GLFW_RELEASE) {
-				glfwSetWindowShouldClose(windowHandle, true);
 		}
-		});
-
-		glfwSetInputMode(windowHandle, GLFW_CURSOR, GLFW_CURSOR_DISABLED);
-		glfwSetInputMode(windowHandle, GLFW_RAW_MOUSE_MOTION, GLFW_TRUE);
-
-		glfwSetWindowPos(windowHandle, 0, 0);
-		glfwSetCursorPos(windowHandle, 0, 0);
-
-		glfwMakeContextCurrent(windowHandle);
-		glfwSwapInterval(1);
-		glfwShowWindow(windowHandle);
-
-		GL.createCapabilities();
-//		GLUtil.setupDebugMessageCallback(System.out);
-		glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
-		glEnable(GL_CULL_FACE);
-		glEnable(GL_DEPTH_TEST);
-		glCullFace(GL_BACK);
-
-		return new WindowInfo(windowHandle, vidMode.width(), vidMode.height());
 	}
 }

client/src/main/java/nl/andrewl/aos2_client/CommunicationHandler.java

@@ -0,0 +1,96 @@
+package nl.andrewl.aos2_client;
+
+import nl.andrewl.aos_core.Net;
+import nl.andrewl.aos_core.net.*;
+import nl.andrewl.aos_core.net.udp.DatagramInit;
+import nl.andrewl.record_net.Message;
+import nl.andrewl.record_net.util.ExtendedDataInputStream;
+import nl.andrewl.record_net.util.ExtendedDataOutputStream;
+
+import java.io.IOException;
+import java.net.DatagramPacket;
+import java.net.DatagramSocket;
+import java.net.InetAddress;
+import java.net.Socket;
+
+public class CommunicationHandler {
+	private Socket socket;
+	private DatagramSocket datagramSocket;
+	private ExtendedDataInputStream in;
+	private ExtendedDataOutputStream out;
+	private int clientId;
+
+	public int establishConnection(InetAddress address, int port, String username) throws IOException {
+		System.out.printf("Connecting to server at %s, port %d, with username \"%s\"...%n", address, port, username);
+		if (socket != null && !socket.isClosed()) {
+			socket.close();
+		}
+		socket = new Socket(address, port);
+		socket.setSoTimeout(1000);
+		in = Net.getInputStream(socket.getInputStream());
+		out = Net.getOutputStream(socket.getOutputStream());
+		Net.write(new ConnectRequestMessage(username), out);
+		Message response = Net.read(in);
+		socket.setSoTimeout(0);
+		if (response instanceof ConnectRejectMessage rejectMessage) {
+			throw new IOException("Attempt to connect rejected: " + rejectMessage.reason());
+		}
+		if (response instanceof ConnectAcceptMessage acceptMessage) {
+			this.clientId = acceptMessage.clientId();
+			new Thread(new TcpReceiver(in, this::handleMessage)).start();
+			establishDatagramConnection();
+			new Thread(new UdpReceiver(datagramSocket, this::handleUdpMessage)).start();
+			return acceptMessage.clientId();
+		} else {
+			throw new IOException("Server returned an unexpected message: " + response);
+		}
+	}
+
+	public void sendMessage(Message msg) {
+		try {
+			Net.write(msg, out);
+		} catch (IOException e) {
+			e.printStackTrace();
+		}
+	}
+
+	public void sendDatagramPacket(Message msg) {
+		try {
+			byte[] data = Net.write(msg);
+			DatagramPacket packet = new DatagramPacket(data, data.length, socket.getRemoteSocketAddress());
+			datagramSocket.send(packet);
+		} catch (IOException e) {
+			e.printStackTrace();
+		}
+	}
+
+	private void establishDatagramConnection() throws IOException {
+		datagramSocket = new DatagramSocket();
+		boolean connectionEstablished = false;
+		int attempts = 0;
+		while (!connectionEstablished && attempts < 100) {
+			sendDatagramPacket(new DatagramInit(clientId));
+			byte[] buffer = new byte[UdpReceiver.MAX_PACKET_SIZE];
+			DatagramPacket packet = new DatagramPacket(buffer, buffer.length);
+			datagramSocket.receive(packet);
+			Message msg = Net.read(buffer);
+			if (msg instanceof DatagramInit echo && echo.clientId() == clientId) {
+				connectionEstablished = true;
+			} else {
+				attempts++;
+			}
+		}
+		if (!connectionEstablished) {
+			throw new IOException("Could not establish a datagram connection to the server after " + attempts + " attempts.");
+		}
+		System.out.println("Established datagram communication with the server.");
+	}
+
+	private void handleMessage(Message msg) {
+		System.out.println("Received message: " + msg);
+	}
+
+	private void handleUdpMessage(Message msg, DatagramPacket packet) {
+		System.out.println("Received udp message: " + msg);
+	}
+}

client/src/main/java/nl/andrewl/aos2_client/render/ChunkMesh.java

@@ -12,7 +12,7 @@ public class ChunkMesh {
 	private final int vaoId;
 	private final int eboId;
 
-	private int indiciesCount;
+	private int indexCount;
 
 	private final int[] positionData;
 	private final Chunk chunk;
@@ -41,14 +41,14 @@ public class ChunkMesh {
 		long start = System.nanoTime();
 		var meshData = ChunkMeshGenerator.generateMesh(chunk);
 		double dur = (System.nanoTime() - start) / 1_000_000.0;
-		this.indiciesCount = meshData.indexBuffer().limit();
+		this.indexCount = meshData.indexBuffer().limit();
 		// Print some debug information.
 		System.out.printf(
 				"Generated mesh for chunk (%d, %d, %d) in %.3f ms. %d vertices, %d indices.%n",
 				chunk.getPosition().x, chunk.getPosition().y, chunk.getPosition().z,
 				dur,
 				meshData.vertexBuffer().limit() / 9,
-				indiciesCount
+				indexCount
 		);
 
 		glBindBuffer(GL_ARRAY_BUFFER, vboId);
@@ -80,7 +80,7 @@ public class ChunkMesh {
 	public void draw() {
 		glBindVertexArray(vaoId);
 		glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, eboId);
-		glDrawElements(GL_TRIANGLES, indiciesCount, GL_UNSIGNED_INT, 0);
+		glDrawElements(GL_TRIANGLES, indexCount, GL_UNSIGNED_INT, 0);
 	}
 
 	public void free() {

client/src/main/java/nl/andrewl/aos2_client/render/WindowUtils.java

@@ -0,0 +1,55 @@
+package nl.andrewl.aos2_client.render;
+
+import org.lwjgl.glfw.Callbacks;
+import org.lwjgl.glfw.GLFWErrorCallback;
+import org.lwjgl.opengl.GL;
+
+import static org.lwjgl.glfw.GLFW.*;
+import static org.lwjgl.opengl.GL11.*;
+
+public class WindowUtils {
+	public static WindowInfo initUI() {
+		GLFWErrorCallback.createPrint(System.err).set();
+		if (!glfwInit()) throw new IllegalStateException("Could not initialize GLFW.");
+		glfwDefaultWindowHints();
+		glfwWindowHint(GLFW_VISIBLE, GLFW_FALSE);
+		glfwWindowHint(GLFW_RESIZABLE, GLFW_FALSE);
+
+		var vidMode = glfwGetVideoMode(glfwGetPrimaryMonitor());
+		if (vidMode == null) throw new IllegalStateException("Could not get information about the primary monitory.");
+		long windowHandle = glfwCreateWindow(vidMode.width(), vidMode.height(), "Ace of Shades 2", glfwGetPrimaryMonitor(), 0);
+		if (windowHandle == 0) throw new RuntimeException("Failed to create GLFW window.");
+
+		glfwSetKeyCallback(windowHandle, (window, key, scancode, action, mods) -> {
+			if (key == GLFW_KEY_ESCAPE && action == GLFW_RELEASE) {
+				glfwSetWindowShouldClose(windowHandle, true);
+			}
+		});
+
+		glfwSetInputMode(windowHandle, GLFW_CURSOR, GLFW_CURSOR_DISABLED);
+		glfwSetInputMode(windowHandle, GLFW_RAW_MOUSE_MOTION, GLFW_TRUE);
+
+		glfwSetWindowPos(windowHandle, 0, 0);
+		glfwSetCursorPos(windowHandle, 0, 0);
+
+		glfwMakeContextCurrent(windowHandle);
+		glfwSwapInterval(1);
+		glfwShowWindow(windowHandle);
+
+		GL.createCapabilities();
+//		GLUtil.setupDebugMessageCallback(System.out);
+		glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
+		glEnable(GL_CULL_FACE);
+		glEnable(GL_DEPTH_TEST);
+		glCullFace(GL_BACK);
+
+		return new WindowInfo(windowHandle, vidMode.width(), vidMode.height());
+	}
+
+	public static void clearUI(long windowHandle) {
+		Callbacks.glfwFreeCallbacks(windowHandle);
+		glfwDestroyWindow(windowHandle);
+		glfwTerminate();
+		glfwSetErrorCallback(null).free();
+	}
+}

core/pom.xml

@@ -35,6 +35,12 @@
             <artifactId>record-net</artifactId>
             <version>v1.2.1</version>
         </dependency>
+        <!-- https://github.com/OpenHFT/Zero-Allocation-Hashing -->
+        <dependency>
+            <groupId>net.openhft</groupId>
+            <artifactId>zero-allocation-hashing</artifactId>
+            <version>0.15</version>
+        </dependency>
 
         <!-- https://mvnrepository.com/artifact/org.junit.jupiter/junit-jupiter-api -->
         <dependency>

core/src/main/java/nl/andrewl/aos_core/Net.java

@@ -1,6 +1,10 @@
 package nl.andrewl.aos_core;
 
+import nl.andrewl.aos_core.net.ChunkHashMessage;
+import nl.andrewl.aos_core.net.ConnectAcceptMessage;
+import nl.andrewl.aos_core.net.ConnectRejectMessage;
 import nl.andrewl.aos_core.net.ConnectRequestMessage;
+import nl.andrewl.aos_core.net.udp.DatagramInit;
 import nl.andrewl.record_net.Message;
 import nl.andrewl.record_net.Serializer;
 import nl.andrewl.record_net.util.ExtendedDataInputStream;
@@ -20,6 +24,10 @@ public final class Net {
 	private static final Serializer serializer = new Serializer();
 	static {
 		serializer.registerType(1, ConnectRequestMessage.class);
+		serializer.registerType(2, ConnectAcceptMessage.class);
+		serializer.registerType(3, ConnectRejectMessage.class);
+		serializer.registerType(4, DatagramInit.class);
+		serializer.registerType(5, ChunkHashMessage.class);
 	}
 
 	public static ExtendedDataInputStream getInputStream(InputStream in) {

core/src/main/java/nl/andrewl/aos_core/model/Chunk.java

@@ -1,5 +1,6 @@
 package nl.andrewl.aos_core.model;
 
+import net.openhft.hashing.LongHashFunction;
 import org.joml.Vector3f;
 import org.joml.Vector3i;
 
@@ -104,6 +105,10 @@ public class Chunk {
 		return sb.toString();
 	}
 
+	public long blockHash() {
+		return LongHashFunction.xx3(0).hashBytes(blocks);
+	}
+
 	public static Chunk random(Vector3i position, Random rand) {
 		Chunk c = new Chunk(position);
 		for (int i = 0; i < TOTAL_SIZE; i++) {

core/src/main/java/nl/andrewl/aos_core/model/Player.java

@@ -8,11 +8,33 @@ public class Player {
 	private final Vector3f velocity;
 	private final Vector2f orientation;
 	private final String username;
+	private final int id;
 
-	public Player(String username) {
+	public Player(int id, String username) {
 		this.position = new Vector3f();
 		this.velocity = new Vector3f();
 		this.orientation = new Vector2f();
+		this.id = id;
 		this.username = username;
 	}
+
+	public Vector3f getPosition() {
+		return position;
+	}
+
+	public Vector3f getVelocity() {
+		return velocity;
+	}
+
+	public Vector2f getOrientation() {
+		return orientation;
+	}
+
+	public String getUsername() {
+		return username;
+	}
+
+	public int getId() {
+		return id;
+	}
 }

core/src/main/java/nl/andrewl/aos_core/net/ChunkHashMessage.java

@@ -0,0 +1,17 @@
+package nl.andrewl.aos_core.net;
+
+import nl.andrewl.record_net.Message;
+
+/**
+ * A message sent by the client, which contains a hash of a chunk, so that the
+ * server can determine if it's up-to-date, or if the server needs to send the
+ * latest chunk data to the user.
+ * @param cx The chunk x coordinate.
+ * @param cy The chunk y coordinate.
+ * @param cz The chunk z coordinate.
+ * @param hash The hash value of the chunk.
+ */
+public record ChunkHashMessage(
+		int cx, int cy, int cz,
+		long hash
+) implements Message {}

core/src/main/java/nl/andrewl/aos_core/net/ConnectAcceptMessage.java

@@ -2,4 +2,11 @@ package nl.andrewl.aos_core.net;
 
 import nl.andrewl.record_net.Message;
 
-public record ConnectAcceptMessage () implements Message {}
+/**
+ * The message that's sent by the server to indicate that a connecting client
+ * has been accepted and can join the server.
+ * @param clientId The client's id.
+ */
+public record ConnectAcceptMessage (
+		int clientId
+) implements Message {}

core/src/main/java/nl/andrewl/aos_core/net/ConnectRejectMessage.java

@@ -2,4 +2,10 @@ package nl.andrewl.aos_core.net;
 
 import nl.andrewl.record_net.Message;
 
-public record ConnectRejectMessage(String reason) implements Message {}
+/**
+ * A message that's sent by the server when a connecting client is rejected.
+ * @param reason The reason for the rejection.
+ */
+public record ConnectRejectMessage(
+		String reason
+) implements Message {}

core/src/main/java/nl/andrewl/aos_core/net/ConnectRequestMessage.java

@@ -2,4 +2,4 @@ package nl.andrewl.aos_core.net;
 
 import nl.andrewl.record_net.Message;
 
-public record ConnectRequestMessage(String username, int udpPort) implements Message {}
+public record ConnectRequestMessage(String username) implements Message {}

core/src/main/java/nl/andrewl/aos_core/net/TcpReceiver.java

@@ -0,0 +1,39 @@
+package nl.andrewl.aos_core.net;
+
+import nl.andrewl.aos_core.Net;
+import nl.andrewl.record_net.Message;
+import nl.andrewl.record_net.util.ExtendedDataInputStream;
+
+import java.io.EOFException;
+import java.io.IOException;
+import java.net.SocketException;
+import java.util.function.Consumer;
+
+public class TcpReceiver implements Runnable {
+	private final ExtendedDataInputStream in;
+	private final Consumer<Message> messageConsumer;
+
+	public TcpReceiver(ExtendedDataInputStream in, Consumer<Message> messageConsumer) {
+		this.in = in;
+		this.messageConsumer = messageConsumer;
+	}
+
+	@Override
+	public void run() {
+		while (true) {
+			try {
+				Message msg = Net.read(in);
+				messageConsumer.accept(msg);
+			} catch (SocketException e) {
+				if (e.getMessage().equals("Socket closed")) {
+					return;
+				}
+				e.printStackTrace();
+			} catch (EOFException e) {
+				return;
+			} catch (IOException e) {
+				e.printStackTrace();
+			}
+		}
+	}
+}

core/src/main/java/nl/andrewl/aos_core/net/UdpMessageHandler.java

@@ -0,0 +1,10 @@
+package nl.andrewl.aos_core.net;
+
+import nl.andrewl.record_net.Message;
+
+import java.net.DatagramPacket;
+
+@FunctionalInterface
+public interface UdpMessageHandler {
+	void handle(Message msg, DatagramPacket packet);
+}

core/src/main/java/nl/andrewl/aos_core/net/UdpReceiver.java

@@ -0,0 +1,44 @@
+package nl.andrewl.aos_core.net;
+
+import nl.andrewl.aos_core.Net;
+import nl.andrewl.record_net.Message;
+
+import java.io.EOFException;
+import java.io.IOException;
+import java.net.DatagramPacket;
+import java.net.DatagramSocket;
+import java.net.SocketException;
+
+public class UdpReceiver implements Runnable {
+	public static final short MAX_PACKET_SIZE = 1400;
+
+	private final DatagramSocket socket;
+	private final UdpMessageHandler handler;
+
+	public UdpReceiver(DatagramSocket socket, UdpMessageHandler handler) {
+		this.socket = socket;
+		this.handler = handler;
+	}
+
+	@Override
+	public void run() {
+		byte[] buffer = new byte[MAX_PACKET_SIZE];
+		DatagramPacket packet = new DatagramPacket(buffer, MAX_PACKET_SIZE);
+		while (true) {
+			try {
+				socket.receive(packet);
+				Message msg = Net.read(buffer);
+				handler.handle(msg, packet);
+			} catch (SocketException e) {
+				if (e.getMessage().equals("Socket closed")) {
+					return;
+				}
+				e.printStackTrace();
+			} catch (EOFException e) {
+				return;
+			} catch (IOException e) {
+				e.printStackTrace();
+			}
+		}
+	}
+}

core/src/main/java/nl/andrewl/aos_core/net/udp/ChunkUpdateMessage.java

@@ -0,0 +1,19 @@
+package nl.andrewl.aos_core.net.udp;
+
+import nl.andrewl.record_net.Message;
+
+/**
+ * A message that's sent to clients when a block in a chunk is updated.
+ * @param cx The chunk x coordinate.
+ * @param cy The chunk y coordinate.
+ * @param cz The chunk z coordinate.
+ * @param lx The local x coordinate in the chunk.
+ * @param ly The local y coordinate in the chunk.
+ * @param lz The local z coordinate in the chunk.
+ * @param newBlock The new block data in the specified position.
+ */
+public record ChunkUpdateMessage(
+		int cx, int cy, int cz,
+		int lx, int ly, int lz,
+		byte newBlock
+) implements Message {}

core/src/main/java/nl/andrewl/aos_core/net/udp/DatagramInit.java

@@ -2,4 +2,11 @@ package nl.andrewl.aos_core.net.udp;
 
 import nl.andrewl.record_net.Message;
 
-public record DatagramInit() implements Message {}
+/**
+ * The message that's sent initially by the client, and responded to by the
+ * server, when a client is establishing a UDP "connection" to the server.
+ * @param clientId The client's id.
+ */
+public record DatagramInit(
+		int clientId
+) implements Message {}

design/net.md

@@ -8,9 +8,9 @@ When referring to the names of packets, we will assume a common package name of
 ### Player Connection
 This workflow is involved in the establishment of a connection between the client and server.
 
-1. Player sends a `ConnectRequestMessage` via TCP, immediately upon opening a socket connection. It contains the player's desired `username`, and their `udpPort` that they will use to connect.
+1. Player sends a `ConnectRequestMessage` via TCP, immediately upon opening a socket connection. It contains the player's desired `username`.
-2. The server will respond with either a `ConnectRejectMessage` with a `reason` for the rejection, or a `ConnectAcceptMessage`.
+2. The server will respond with either a `ConnectRejectMessage` with a `reason` for the rejection, or a `ConnectAcceptMessage` containing the client's `clientId`.
-3. If the player received an acceptance message, they will then send a `DatagramInit` to the server's UDP socket (on the same address/port). The player should keep sending such an init message until they receive a `DatagramInit` message echoed back as a response. The player should then stop sending init messages, and expect to begin receiving normal communication data through the datagram socket.
+3. If the player received an acceptance message, they will then send a `DatagramInit` to the server's UDP socket (on the same address/port) containing the `clientId` received in the `ConnectAcceptMessage`. The player should keep sending such an init message until they receive a `DatagramInit` message echoed back as a response. The player should then stop sending init messages, and expect to begin receiving normal communication data through the datagram socket.
 
 ### World Data
 A combination of TCP and UDP communication is used to ensure that all connected clients have the latest information about the state of the world.

server/src/main/java/nl/andrewl/aos2_server/ClientCommunicationHandler.java

@@ -1,85 +1,73 @@
 package nl.andrewl.aos2_server;
 
 import nl.andrewl.aos_core.Net;
+import nl.andrewl.aos_core.model.Player;
+import nl.andrewl.aos_core.net.ConnectAcceptMessage;
 import nl.andrewl.aos_core.net.ConnectRejectMessage;
 import nl.andrewl.aos_core.net.ConnectRequestMessage;
+import nl.andrewl.aos_core.net.TcpReceiver;
 import nl.andrewl.record_net.Message;
 import nl.andrewl.record_net.util.ExtendedDataInputStream;
 import nl.andrewl.record_net.util.ExtendedDataOutputStream;
 
-import java.io.EOFException;
 import java.io.IOException;
-import java.net.*;
+import java.net.DatagramPacket;
-
+import java.net.DatagramSocket;
-public class ClientHandler extends Thread {
+import java.net.InetAddress;
-	private static int nextThreadId = 1;
+import java.net.Socket;
 
+public class ClientCommunicationHandler {
 	private final Server server;
 	private final Socket socket;
 	private final DatagramSocket datagramSocket;
 	private final ExtendedDataInputStream in;
 	private final ExtendedDataOutputStream out;
 
-	private volatile boolean running;
 	private InetAddress clientAddress;
 	private int clientUdpPort;
+	private Player player;
 
-	public ClientHandler(Server server, Socket socket, DatagramSocket datagramSocket) throws IOException {
+	public ClientCommunicationHandler(Server server, Socket socket, DatagramSocket datagramSocket) throws IOException {
-		super("aos-client-handler-" + nextThreadId++);
 		this.server = server;
 		this.socket = socket;
 		this.datagramSocket = datagramSocket;
 		this.in = Net.getInputStream(socket.getInputStream());
 		this.out = Net.getOutputStream(socket.getOutputStream());
+		establishConnection();
+		new Thread(new TcpReceiver(in, this::handleTcpMessage)).start();
 	}
 
 	public void shutdown() {
-		running = false;
-	}
-
-	@Override
-	public void run() {
-		running = true;
-		establishConnection();
-		while (running) {
 		try {
-				Message msg = Net.read(in);
+			socket.close();
-			} catch (SocketException e) {
-				if (e.getMessage().equals("Socket closed") | e.getMessage().equals("Connection reset")) {
-					shutdown();
-				} else {
-					e.printStackTrace();
-				}
-			} catch (EOFException e) {
-				shutdown();
 		} catch (IOException e) {
 			e.printStackTrace();
-				shutdown();
-			}
 		}
 	}
 
-	private void establishConnection() {
+	public void setClientUdpPort(int port) {
-		try {
+		this.clientUdpPort = port;
-			socket.setSoTimeout(1000);
-		} catch (SocketException e) {
-			throw new RuntimeException(e);
 	}
+
+	private void handleTcpMessage(Message msg) {
+		System.out.println("Message received from client " + player.getUsername() + ": " + msg);
+	}
+
+	private void establishConnection() throws IOException {
+		socket.setSoTimeout(1000);
 		boolean connectionEstablished = false;
 		int attempts = 0;
 		while (!connectionEstablished && attempts < 100) {
 			try {
 				Message msg = Net.read(in);
 				if (msg instanceof ConnectRequestMessage connectMsg) {
+					// Try to set the TCP timeout back to 0 now that we've got the correct request.
+					socket.setSoTimeout(0);
 					this.clientAddress = socket.getInetAddress();
-					this.clientUdpPort = connectMsg.udpPort();
 					System.out.println("Player connected: " + connectMsg.username());
 					connectionEstablished = true;
-					try {
+					this.player = server.registerPlayer(this, connectMsg.username());
-						socket.setSoTimeout(0);
+					Net.write(new ConnectAcceptMessage(player.getId()), out);
-					} catch (SocketException e) {
-						throw new RuntimeException(e);
-					}
 				}
 			} catch (IOException e) {
 				e.printStackTrace();
@@ -93,11 +81,11 @@ public class ClientHandler extends Thread {
 				e.printStackTrace();
 			}
 			System.out.println("Player couldn't connect after " + attempts + " attempts. Aborting.");
-			shutdown();
+			socket.close();
 		}
 	}
 
-	private void sendDatagramPacket(Message msg) {
+	public void sendDatagramPacket(Message msg) {
 		try {
 			sendDatagramPacket(Net.write(msg));
 		} catch (IOException e) {
@@ -105,12 +93,12 @@ public class ClientHandler extends Thread {
 		}
 	}
 
-	private void sendDatagramPacket(byte[] data) {
+	public void sendDatagramPacket(byte[] data) {
 		DatagramPacket packet = new DatagramPacket(data, data.length, clientAddress, clientUdpPort);
 		sendDatagramPacket(packet);
 	}
 
-	private void sendDatagramPacket(DatagramPacket packet) {
+	public void sendDatagramPacket(DatagramPacket packet) {
 		try {
 			packet.setAddress(clientAddress);
 			packet.setPort(clientUdpPort);

server/src/main/java/nl/andrewl/aos2_server/Server.java

@@ -1,22 +1,26 @@
 package nl.andrewl.aos2_server;
 
+import nl.andrewl.aos_core.model.Player;
+import nl.andrewl.aos_core.net.UdpReceiver;
+import nl.andrewl.aos_core.net.udp.DatagramInit;
+import nl.andrewl.record_net.Message;
+
 import java.io.IOException;
-import java.net.DatagramSocket;
+import java.net.*;
-import java.net.ServerSocket;
+import java.util.HashMap;
-import java.net.Socket;
-import java.net.SocketException;
 import java.util.HashSet;
+import java.util.Map;
 import java.util.Set;
 
 public class Server implements Runnable {
 	private final ServerSocket serverSocket;
 	private final DatagramSocket datagramSocket;
 	private volatile boolean running;
-	private Set<ClientHandler> clientHandlers;
 
-	public static void main(String[] args) throws IOException {
+	private int nextClientId = 1;
-		new Server().run();
+	private final Set<ClientCommunicationHandler> clientHandlers;
-	}
+	private final Map<Integer, Player> players;
+	private final Map<Integer, ClientCommunicationHandler> playerClientHandlers;
 
 	public Server() throws IOException {
 		this.serverSocket = new ServerSocket(24464, 5);
@@ -24,22 +28,49 @@ public class Server implements Runnable {
 		this.datagramSocket = new DatagramSocket(24464);
 		this.datagramSocket.setReuseAddress(true);
 		this.clientHandlers = new HashSet<>();
+		this.players = new HashMap<>();
+		this.playerClientHandlers = new HashMap<>();
 	}
 
 	@Override
 	public void run() {
 		running = true;
+		new Thread(new UdpReceiver(datagramSocket, this::handleUdpMessage)).start();
 		System.out.println("Started AOS2-Server on TCP/UDP port " + serverSocket.getLocalPort() + "; now accepting connections.");
 		while (running) {
 			acceptClientConnection();
 		}
+		datagramSocket.close();
+		for (var handler : clientHandlers) handler.shutdown();
+	}
+
+	public void handleUdpMessage(Message msg, DatagramPacket packet) {
+		// Echo any init message from known clients.
+		if (msg instanceof DatagramInit init) {
+			var handler = getHandler(init.clientId());
+			if (handler != null) {
+				handler.setClientUdpPort(packet.getPort());
+				handler.sendDatagramPacket(msg);
+			}
+		}
+	}
+
+	public synchronized Player registerPlayer(ClientCommunicationHandler handler, String username) {
+		Player player = new Player(nextClientId++, username);
+		players.put(player.getId(), player);
+		playerClientHandlers.put(player.getId(), handler);
+		System.out.println("Registered player " + username + " with id " + player.getId());
+		return player;
+	}
+
+	public ClientCommunicationHandler getHandler(int id) {
+		return playerClientHandlers.get(id);
 	}
 
 	private void acceptClientConnection() {
 		try {
 			Socket clientSocket = serverSocket.accept();
-			ClientHandler handler = new ClientHandler(this, clientSocket, datagramSocket);
+			ClientCommunicationHandler handler = new ClientCommunicationHandler(this, clientSocket, datagramSocket);
-			handler.start();
 			clientHandlers.add(handler);
 		} catch (IOException e) {
 			if (e instanceof SocketException && !this.running && e.getMessage().equalsIgnoreCase("Socket closed")) {
@@ -48,4 +79,8 @@ public class Server implements Runnable {
 			e.printStackTrace();
 		}
 	}
+
+	public static void main(String[] args) throws IOException {
+		new Server().run();
+	}
 }