first commit

.gitignore

@@ -0,0 +1,4 @@
+.gradle
+.idea
+build
+client-fabric/run

LICENSE.md

@@ -0,0 +1,347 @@
+Mozilla Public License Version 2.0
+==================================
+
+### 1. Definitions
+
+**1.1. “Contributor”**  
+means each individual or legal entity that creates, contributes to
+the creation of, or owns Covered Software.
+
+**1.2. “Contributor Version”**  
+means the combination of the Contributions of others (if any) used
+by a Contributor and that particular Contributor's Contribution.
+
+**1.3. “Contribution”**  
+means Covered Software of a particular Contributor.
+
+**1.4. “Covered Software”**  
+means Source Code Form to which the initial Contributor has attached
+the notice in Exhibit A, the Executable Form of such Source Code
+Form, and Modifications of such Source Code Form, in each case
+including portions thereof.
+
+**1.5. “Incompatible With Secondary Licenses”**  
+means
+
+* **(a)** that the initial Contributor has attached the notice described
+  in Exhibit B to the Covered Software; or
+* **(b)** that the Covered Software was made available under the terms of
+  version 1.1 or earlier of the License, but not also under the
+  terms of a Secondary License.
+
+**1.6. “Executable Form”**  
+means any form of the work other than Source Code Form.
+
+**1.7. “Larger Work”**  
+means a work that combines Covered Software with other material, in
+a separate file or files, that is not Covered Software.
+
+**1.8. “License”**  
+means this document.
+
+**1.9. “Licensable”**  
+means having the right to grant, to the maximum extent possible,
+whether at the time of the initial grant or subsequently, any and
+all of the rights conveyed by this License.
+
+**1.10. “Modifications”**  
+means any of the following:
+
+* **(a)** any file in Source Code Form that results from an addition to,
+  deletion from, or modification of the contents of Covered
+  Software; or
+* **(b)** any new file in Source Code Form that contains any Covered
+  Software.
+
+**1.11. “Patent Claims” of a Contributor**  
+means any patent claim(s), including without limitation, method,
+process, and apparatus claims, in any patent Licensable by such
+Contributor that would be infringed, but for the grant of the
+License, by the making, using, selling, offering for sale, having
+made, import, or transfer of either its Contributions or its
+Contributor Version.
+
+**1.12. “Secondary License”**  
+means either the GNU General Public License, Version 2.0, the GNU
+Lesser General Public License, Version 2.1, the GNU Affero General
+Public License, Version 3.0, or any later versions of those
+licenses.
+
+**1.13. “Source Code Form”**  
+means the form of the work preferred for making modifications.
+
+**1.14. “You” (or “Your”)**  
+means an individual or a legal entity exercising rights under this
+License. For legal entities, “You” includes any entity that
+controls, is controlled by, or is under common control with You. For
+purposes of this definition, “control” means **(a)** the power, direct
+or indirect, to cause the direction or management of such entity,
+whether by contract or otherwise, or **(b)** ownership of more than
+fifty percent (50%) of the outstanding shares or beneficial
+ownership of such entity.
+
+### 2. License Grants and Conditions
+
+#### 2.1. Grants
+
+Each Contributor hereby grants You a world-wide, royalty-free,
+non-exclusive license:
+
+* **(a)** under intellectual property rights (other than patent or trademark)
+  Licensable by such Contributor to use, reproduce, make available,
+  modify, display, perform, distribute, and otherwise exploit its
+  Contributions, either on an unmodified basis, with Modifications, or
+  as part of a Larger Work; and
+* **(b)** under Patent Claims of such Contributor to make, use, sell, offer
+  for sale, have made, import, and otherwise transfer either its
+  Contributions or its Contributor Version.
+
+#### 2.2. Effective Date
+
+The licenses granted in Section 2.1 with respect to any Contribution
+become effective for each Contribution on the date the Contributor first
+distributes such Contribution.
+
+#### 2.3. Limitations on Grant Scope
+
+The licenses granted in this Section 2 are the only rights granted under
+this License. No additional rights or licenses will be implied from the
+distribution or licensing of Covered Software under this License.
+Notwithstanding Section 2.1(b) above, no patent license is granted by a
+Contributor:
+
+* **(a)** for any code that a Contributor has removed from Covered Software;
+  or
+* **(b)** for infringements caused by: **(i)** Your and any other third party's
+  modifications of Covered Software, or **(ii)** the combination of its
+  Contributions with other software (except as part of its Contributor
+  Version); or
+* **(c)** under Patent Claims infringed by Covered Software in the absence of
+  its Contributions.
+
+This License does not grant any rights in the trademarks, service marks,
+or logos of any Contributor (except as may be necessary to comply with
+the notice requirements in Section 3.4).
+
+#### 2.4. Subsequent Licenses
+
+No Contributor makes additional grants as a result of Your choice to
+distribute the Covered Software under a subsequent version of this
+License (see Section 10.2) or under the terms of a Secondary License (if
+permitted under the terms of Section 3.3).
+
+#### 2.5. Representation
+
+Each Contributor represents that the Contributor believes its
+Contributions are its original creation(s) or it has sufficient rights
+to grant the rights to its Contributions conveyed by this License.
+
+#### 2.6. Fair Use
+
+This License is not intended to limit any rights You have under
+applicable copyright doctrines of fair use, fair dealing, or other
+equivalents.
+
+#### 2.7. Conditions
+
+Sections 3.1, 3.2, 3.3, and 3.4 are conditions of the licenses granted
+in Section 2.1.
+
+### 3. Responsibilities
+
+#### 3.1. Distribution of Source Form
+
+All distribution of Covered Software in Source Code Form, including any
+Modifications that You create or to which You contribute, must be under
+the terms of this License. You must inform recipients that the Source
+Code Form of the Covered Software is governed by the terms of this
+License, and how they can obtain a copy of this License. You may not
+attempt to alter or restrict the recipients' rights in the Source Code
+Form.
+
+#### 3.2. Distribution of Executable Form
+
+If You distribute Covered Software in Executable Form then:
+
+* **(a)** such Covered Software must also be made available in Source Code
+  Form, as described in Section 3.1, and You must inform recipients of
+  the Executable Form how they can obtain a copy of such Source Code
+  Form by reasonable means in a timely manner, at a charge no more
+  than the cost of distribution to the recipient; and
+
+* **(b)** You may distribute such Executable Form under the terms of this
+  License, or sublicense it under different terms, provided that the
+  license for the Executable Form does not attempt to limit or alter
+  the recipients' rights in the Source Code Form under this License.
+
+#### 3.3. Distribution of a Larger Work
+
+You may create and distribute a Larger Work under terms of Your choice,
+provided that You also comply with the requirements of this License for
+the Covered Software. If the Larger Work is a combination of Covered
+Software with a work governed by one or more Secondary Licenses, and the
+Covered Software is not Incompatible With Secondary Licenses, this
+License permits You to additionally distribute such Covered Software
+under the terms of such Secondary License(s), so that the recipient of
+the Larger Work may, at their option, further distribute the Covered
+Software under the terms of either this License or such Secondary
+License(s).
+
+#### 3.4. Notices
+
+You may not remove or alter the substance of any license notices
+(including copyright notices, patent notices, disclaimers of warranty,
+or limitations of liability) contained within the Source Code Form of
+the Covered Software, except that You may alter any license notices to
+the extent required to remedy known factual inaccuracies.
+
+#### 3.5. Application of Additional Terms
+
+You may choose to offer, and to charge a fee for, warranty, support,
+indemnity or liability obligations to one or more recipients of Covered
+Software. However, You may do so only on Your own behalf, and not on
+behalf of any Contributor. You must make it absolutely clear that any
+such warranty, support, indemnity, or liability obligation is offered by
+You alone, and You hereby agree to indemnify every Contributor for any
+liability incurred by such Contributor as a result of warranty, support,
+indemnity or liability terms You offer. You may include additional
+disclaimers of warranty and limitations of liability specific to any
+jurisdiction.
+
+### 4. Inability to Comply Due to Statute or Regulation
+
+If it is impossible for You to comply with any of the terms of this
+License with respect to some or all of the Covered Software due to
+statute, judicial order, or regulation then You must: **(a)** comply with
+the terms of this License to the maximum extent possible; and **(b)**
+describe the limitations and the code they affect. Such description must
+be placed in a text file included with all distributions of the Covered
+Software under this License. Except to the extent prohibited by statute
+or regulation, such description must be sufficiently detailed for a
+recipient of ordinary skill to be able to understand it.
+
+### 5. Termination
+
+**5.1.** The rights granted under this License will terminate automatically
+if You fail to comply with any of its terms. However, if You become
+compliant, then the rights granted under this License from a particular
+Contributor are reinstated **(a)** provisionally, unless and until such
+Contributor explicitly and finally terminates Your grants, and **(b)** on an
+ongoing basis, if such Contributor fails to notify You of the
+non-compliance by some reasonable means prior to 60 days after You have
+come back into compliance. Moreover, Your grants from a particular
+Contributor are reinstated on an ongoing basis if such Contributor
+notifies You of the non-compliance by some reasonable means, this is the
+first time You have received notice of non-compliance with this License
+from such Contributor, and You become compliant prior to 30 days after
+Your receipt of the notice.
+
+**5.2.** If You initiate litigation against any entity by asserting a patent
+infringement claim (excluding declaratory judgment actions,
+counter-claims, and cross-claims) alleging that a Contributor Version
+directly or indirectly infringes any patent, then the rights granted to
+You by any and all Contributors for the Covered Software under Section
+2.1 of this License shall terminate.
+
+**5.3.** In the event of termination under Sections 5.1 or 5.2 above, all
+end user license agreements (excluding distributors and resellers) which
+have been validly granted by You or Your distributors under this License
+prior to termination shall survive termination.
+
+### 6. Disclaimer of Warranty
+
+> Covered Software is provided under this License on an “as is”
+> basis, without warranty of any kind, either expressed, implied, or
+> statutory, including, without limitation, warranties that the
+> Covered Software is free of defects, merchantable, fit for a
+> particular purpose or non-infringing. The entire risk as to the
+> quality and performance of the Covered Software is with You.
+> Should any Covered Software prove defective in any respect, You
+> (not any Contributor) assume the cost of any necessary servicing,
+> repair, or correction. This disclaimer of warranty constitutes an
+> essential part of this License. No use of any Covered Software is
+> authorized under this License except under this disclaimer.
+
+### 7. Limitation of Liability
+
+> Under no circumstances and under no legal theory, whether tort
+> (including negligence), contract, or otherwise, shall any
+> Contributor, or anyone who distributes Covered Software as
+> permitted above, be liable to You for any direct, indirect,
+> special, incidental, or consequential damages of any character
+> including, without limitation, damages for lost profits, loss of
+> goodwill, work stoppage, computer failure or malfunction, or any
+> and all other commercial damages or losses, even if such party
+> shall have been informed of the possibility of such damages. This
+> limitation of liability shall not apply to liability for death or
+> personal injury resulting from such party's negligence to the
+> extent applicable law prohibits such limitation. Some
+> jurisdictions do not allow the exclusion or limitation of
+> incidental or consequential damages, so this exclusion and
+> limitation may not apply to You.
+
+### 8. Litigation
+
+Any litigation relating to this License may be brought only in the
+courts of a jurisdiction where the defendant maintains its principal
+place of business and such litigation shall be governed by laws of that
+jurisdiction, without reference to its conflict-of-law provisions.
+Nothing in this Section shall prevent a party's ability to bring
+cross-claims or counter-claims.
+
+### 9. Miscellaneous
+
+This License represents the complete agreement concerning the subject
+matter hereof. If any provision of this License is held to be
+unenforceable, such provision shall be reformed only to the extent
+necessary to make it enforceable. Any law or regulation which provides
+that the language of a contract shall be construed against the drafter
+shall not be used to construe this License against a Contributor.
+
+### 10. Versions of the License
+
+#### 10.1. New Versions
+
+Mozilla Foundation is the license steward. Except as provided in Section
+10.3, no one other than the license steward has the right to modify or
+publish new versions of this License. Each version will be given a
+distinguishing version number.
+
+#### 10.2. Effect of New Versions
+
+You may distribute the Covered Software under the terms of the version
+of the License under which You originally received the Covered Software,
+or under the terms of any subsequent version published by the license
+steward.
+
+#### 10.3. Modified Versions
+
+If you create software not governed by this License, and you want to
+create a new license for such software, you may create and use a
+modified version of this License if you rename the license and remove
+any references to the name of the license steward (except to note that
+such modified license differs from this License).
+
+#### 10.4. Distributing Source Code Form that is Incompatible With Secondary Licenses
+
+If You choose to distribute Source Code Form that is Incompatible With
+Secondary Licenses under the terms of this version of the License, the
+notice described in Exhibit B of this License must be attached.
+
+## Exhibit A - Source Code Form License Notice
+
+    This Source Code Form is subject to the terms of the Mozilla Public
+    License, v. 2.0. If a copy of the MPL was not distributed with this
+    file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+If it is not possible or desirable to put the notice in a particular
+file, then You may include the notice in a location (such as a LICENSE
+file in a relevant directory) where a recipient would be likely to look
+for such a notice.
+
+You may add additional accurate notices of copyright ownership.
+
+## Exhibit B - “Incompatible With Secondary Licenses” Notice
+
+    This Source Code Form is "Incompatible With Secondary Licenses", as
+    defined by the Mozilla Public License, v. 2.0.

build.gradle

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+plugins {
+    id 'java'
+}

client-fabric/build.gradle

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+plugins {
+    id 'fabric-loom' version '1.8-SNAPSHOT'
+}
+
+repositories {
+    mavenCentral()
+}
+
+dependencies {
+    minecraft "com.mojang:minecraft:${project.minecraft_version}"
+    mappings "net.fabricmc:yarn:${project.yarn_mappings}:v2"
+    modImplementation "net.fabricmc:fabric-loader:${project.loader_version}"
+
+    modImplementation "net.fabricmc.fabric-api:fabric-api:${project.fabric_version}"
+
+    implementation project(':common')
+}
+
+sourceSets {
+    main.java.srcDirs = ['src']
+    main.resources.srcDirs = ['resources']
+}
+
+processResources {
+    inputs.property "version", version
+
+    filesMatching("fabric.mod.json") {
+        expand "version": version
+    }
+}
+
+tasks.withType(JavaCompile).configureEach {
+    it.options.release = 21
+}
+
+java {
+    sourceCompatibility = JavaVersion.VERSION_21
+    targetCompatibility = JavaVersion.VERSION_21
+}
+
+jar {
+    from("LICENSE") {
+        rename { "${it}_${project.base.archivesName.get()}" }
+    }
+}

client-fabric/gradle.properties

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+org.gradle.jvmargs=-Xmx1G
+org.gradle.parallel=true
+# https://fabricmc.net/develop
+minecraft_version=1.21.3
+yarn_mappings=1.21.3+build.2
+loader_version=0.16.9
+fabric_version=0.108.0+1.21.3

client-fabric/resources/fabric.mod.json

@@ -0,0 +1,33 @@
+{
+  "schemaVersion": 1,
+  "id": "svc",
+  "version": "${version}",
+  "name": "Simpler Voice Chat",
+  "description": "Simpler voice chat for our favorite block game",
+  "authors": [
+    "1e99"
+  ],
+  "contact": {
+    "sources": "https://git.1e99.eu/1e99/simplervoicechat"
+  },
+  "license": "MPL-2.0",
+  "icon": "assets/svc/icon.png",
+  "environment": "*",
+  "entrypoints": {
+    "client": [
+      "eu.e99.svc.client.fabric.FabricSimplerVoiceChat"
+    ]
+  },
+  "mixins": [
+    {
+      "config": "svc.mixins.json",
+      "environment": "client"
+    }
+  ],
+  "depends": {
+    "fabricloader": ">=0.16.7",
+    "minecraft": "~1.21.3",
+    "java": ">=21",
+    "fabric-api": "*"
+  }
+}

client-fabric/resources/svc.mixins.json

@@ -0,0 +1,10 @@
+{
+  "required": true,
+  "package": "eu.e99.svc.client.fabric.mixin",
+  "compatibilityLevel": "JAVA_21",
+  "mixins": [
+  ],
+  "injectors": {
+    "defaultRequire": 1
+  }
+}

client-fabric/src/eu/e99/svc/client/fabric/FabricSimplerVoiceChat.java

@@ -0,0 +1,18 @@
+package eu.e99.svc.client.fabric;
+
+import net.fabricmc.api.ClientModInitializer;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public class FabricSimplerVoiceChat implements ClientModInitializer {
+
+    public static final String NAMESPACE = "svc";
+    public static final Logger LOGGER = LoggerFactory.getLogger(NAMESPACE);
+
+    @Override
+    public void onInitializeClient() {
+        LOGGER.info("Simpler Voice Chat Running");
+
+
+    }
+}

common/build.gradle

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+plugins {
+    id 'java'
+}
+
+repositories {
+    mavenCentral()
+}
+
+dependencies {
+    implementation 'com.google.code.gson:gson:2.11.0'
+}
+
+sourceSets {
+    main.java.srcDirs = ['src']
+    main.resources.srcDirs = ['resources']
+}

common/src/eu/e99/svc/AllTrustManager.java

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+package eu.e99.svc;
+
+import javax.net.ssl.X509TrustManager;
+import java.security.cert.X509Certificate;
+
+public class AllTrustManager implements X509TrustManager {
+
+    @Override
+    public void checkClientTrusted(X509Certificate[] chain, String authType) {
+    }
+
+    @Override
+    public void checkServerTrusted(X509Certificate[] chain, String authType) {
+    }
+
+    @Override
+    public X509Certificate[] getAcceptedIssuers() {
+        return new X509Certificate[0];
+    }
+}

common/src/eu/e99/svc/Connection.java

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+package eu.e99.svc;
+
+import eu.e99.svc.io.BinaryMessage;
+import eu.e99.svc.io.Reader;
+import eu.e99.svc.io.Writer;
+import eu.e99.svc.packet.DisconnectPacket;
+
+import java.io.IOException;
+import java.net.Socket;
+
+public class Connection {
+
+    private final Socket socket;
+    private final Reader reader;
+    private final Writer writer;
+
+    public Connection(Socket socket) throws IOException {
+        this.socket = socket;
+        this.reader = new Reader(this.socket.getInputStream());
+        this.writer = new Writer(this.socket.getOutputStream());
+    }
+
+    public void writePacket(BinaryMessage packet) throws IOException {
+        synchronized (this.socket) {
+            SimplerVoiceChat.PACKETS.writeMessage(packet, this.writer);
+        }
+    }
+
+    public BinaryMessage readPacket() throws IOException {
+        synchronized (this.socket) {
+            return SimplerVoiceChat.PACKETS.readMessage(this.reader);
+        }
+    }
+
+    public void disconnect(String reason) throws IOException {
+        DisconnectPacket disconnect = new DisconnectPacket();
+        disconnect.reason = reason;
+        this.writePacket(disconnect);
+        this.socket.close();
+    }
+}

common/src/eu/e99/svc/SimplerVoiceChat.java

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+package eu.e99.svc;
+
+import eu.e99.svc.io.BinaryMessage;
+import eu.e99.svc.io.MessageRegistry;
+import eu.e99.svc.packet.*;
+
+import javax.net.ssl.SSLContext;
+import javax.net.ssl.SSLSocketFactory;
+import javax.net.ssl.TrustManager;
+import java.io.IOException;
+import java.net.InetSocketAddress;
+import java.net.Socket;
+import java.security.KeyManagementException;
+import java.security.NoSuchAlgorithmException;
+import java.security.SecureRandom;
+
+public class SimplerVoiceChat {
+
+    public static final int PROTOCOL_VERSION = 0;
+
+    public static final MessageRegistry PACKETS = new MessageRegistry();
+    public static final MessageRegistry MESSAGES = new MessageRegistry();
+
+    static {
+        PACKETS.registerMessage(0, ClientHelloPacket::new);
+        // TODO: Keep alive?
+        PACKETS.registerMessage(2, AuthRequestPacket::new);
+        PACKETS.registerMessage(3, AuthResponsePacket::new);
+        PACKETS.registerMessage(4, AuthSuccessPacket::new);
+        PACKETS.registerMessage(100, MessagePacket::new);
+        PACKETS.registerMessage(255, DisconnectPacket::new);
+    }
+
+
+    public static void main(String[] args) throws NoSuchAlgorithmException, KeyManagementException {
+        TrustManager[] trustManagers = new TrustManager[]{
+                new AllTrustManager(),
+        };
+
+        SSLContext sslContext = SSLContext.getInstance("TLS");
+        sslContext.init(null, trustManagers, new SecureRandom());
+
+        SSLSocketFactory socketFactory = sslContext.getSocketFactory();
+
+        SimplerVoiceChat voiceChat = new SimplerVoiceChat("localhost", 6969, socketFactory);
+        voiceChat.start();
+    }
+
+    private final String host;
+    private final int port;
+    private final SSLSocketFactory socketFactory;
+
+    public SimplerVoiceChat(String host, int port, SSLSocketFactory socketFactory) {
+        this.host = host;
+        this.port = port;
+        this.socketFactory = socketFactory;
+    }
+
+    public void start() {
+        // Connect and auth
+
+        try (Socket socket = this.socketFactory.createSocket()) {
+            socket.connect(new InetSocketAddress(this.host, this.port));
+            Connection conn = new Connection(socket);
+
+            this.handleHandshake(conn);
+        } catch (IOException e) {
+            System.out.printf("Failed to connect.%n");
+            e.printStackTrace(System.out);
+        }
+    }
+
+    private void handleHandshake(Connection conn) throws IOException {
+        ClientHelloPacket clientHello = new ClientHelloPacket();
+        clientHello.version = PROTOCOL_VERSION;
+        conn.writePacket(clientHello);
+
+        while (true) {
+            BinaryMessage packet = conn.readPacket();
+
+            switch (packet) {
+                case AuthRequestPacket authRequest -> {
+                    System.out.printf("Joining fake server to authenticate.%n");
+
+                    AuthResponsePacket authResponse = new AuthResponsePacket();
+                    authResponse.username = "Test";
+                    conn.writePacket(authResponse);
+                }
+                case AuthSuccessPacket authComplete -> {
+                    System.out.printf("Successfully authenticated.%n");
+                    return;
+                }
+                default -> {
+                    System.out.printf("Got unexpected packet.%n");
+                }
+            }
+        }
+
+    }
+}

common/src/eu/e99/svc/auth/MojangAPI.java

@@ -0,0 +1,42 @@
+package eu.e99.svc.auth;
+
+import com.google.gson.JsonObject;
+import com.google.gson.JsonParser;
+
+import java.io.IOException;
+import java.net.URI;
+import java.net.http.HttpClient;
+import java.net.http.HttpRequest;
+import java.net.http.HttpResponse;
+import java.util.UUID;
+
+// https://wiki.vg/Protocol_Encryption
+public class MojangAPI {
+
+    public static PlayerProfile hasJoined(String username, String serverId) throws IOException, InterruptedException {
+        try (HttpClient client = HttpClient.newHttpClient()) {
+            String loc = String.format("https://sessionserver.mojang.com/session/minecraft/hasJoined?username=%s&serverId=%s", username, serverId);
+            URI uri = URI.create(loc);
+
+            HttpRequest req = HttpRequest.newBuilder()
+                    .uri(uri)
+                    .GET()
+                    .build();
+
+            HttpResponse<String> res = client.send(req, HttpResponse.BodyHandlers.ofString());
+            if (res.statusCode() == 204) {
+                return null;
+            }
+
+            JsonObject object = JsonParser
+                    .parseString(res.body())
+                    .getAsJsonObject();
+
+            String name = object.get("name").getAsString();
+            String rawUuid = object.get("id").getAsString();
+            UUID uuid = UUID.fromString(rawUuid.replaceFirst("(\\w{8})(\\w{4})(\\w{4})(\\w{4})(\\w{12})", "$1-$2-$3-$4-$5"));
+
+            return new PlayerProfile(name, uuid);
+        }
+    }
+}

common/src/eu/e99/svc/auth/PlayerProfile.java

@@ -0,0 +1,11 @@
+package eu.e99.svc.auth;
+
+import java.util.UUID;
+
+public record PlayerProfile(
+        String username,
+        UUID uuid
+) {
+
+
+}

common/src/eu/e99/svc/io/BinaryMessage.java

@@ -0,0 +1,10 @@
+package eu.e99.svc.io;
+
+import java.io.IOException;
+
+public interface BinaryMessage {
+
+    void read(Reader reader) throws IOException;
+
+    void write(Writer writer) throws IOException;
+}

common/src/eu/e99/svc/io/MessageRegistry.java

@@ -0,0 +1,50 @@
+package eu.e99.svc.io;
+
+import eu.e99.svc.packet.*;
+
+import java.io.IOException;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.function.Supplier;
+
+public class MessageRegistry {
+
+    private final Map<Integer, Supplier<? extends BinaryMessage>> messagesById;
+    private final Map<Class<? extends BinaryMessage>, Integer> messagesByClass;
+
+    public MessageRegistry() {
+        this.messagesById = new HashMap<>();
+        this.messagesByClass = new HashMap<>();
+    }
+
+    public BinaryMessage readMessage(Reader reader) throws IOException {
+        int id = reader.readInt();
+        Supplier<? extends BinaryMessage> supplier = this.messagesById.get(id);;
+        if (supplier == null) {
+            throw new RuntimeException("Failed to find message with id " + id);
+        }
+
+        BinaryMessage msg = supplier.get();
+        msg.read(reader);
+        return msg;
+    }
+
+    public void writeMessage(BinaryMessage msg, Writer writer) throws IOException {
+        Class<? extends BinaryMessage> clazz = msg.getClass();
+        Integer id = this.messagesByClass.get(clazz);
+        if (id == null) {
+            throw new IllegalArgumentException("Unknown message sent.");
+        }
+
+        writer.writeInt(id);
+        msg.write(writer);
+    }
+
+    public void registerMessage(int id, Supplier<? extends BinaryMessage> supplier) {
+        BinaryMessage msg = supplier.get();
+        Class<? extends BinaryMessage> clazz = msg.getClass();
+
+        this.messagesById.put(id, supplier);
+        this.messagesByClass.put(clazz, id);
+    }
+}

common/src/eu/e99/svc/io/Reader.java

@@ -0,0 +1,48 @@
+package eu.e99.svc.io;
+
+import java.io.DataInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.nio.charset.StandardCharsets;
+import java.util.UUID;
+
+public class Reader {
+
+    private final DataInputStream in;
+
+    public Reader(InputStream in) {
+        this.in = new DataInputStream(in);
+    }
+
+    public int readInt() throws IOException {
+        return this.in.readInt();
+    }
+
+    public long readLong() throws IOException {
+        return this.in.readLong();
+    }
+
+    public boolean readBool() throws IOException {
+        return this.in.readBoolean();
+    }
+
+    public String readString() throws IOException {
+        byte[] bytes = this.readByteArray();
+        return new String(bytes, StandardCharsets.UTF_8);
+    }
+
+    public byte[] readByteArray() throws IOException {
+        int length = this.readInt();
+        byte[] bytes = new byte[length];
+        this.in.readFully(bytes);
+
+        return bytes;
+    }
+
+    public UUID readUUID() throws IOException {
+        long most = this.readLong();
+        long least = this.readLong();
+
+        return new UUID(most, least);
+    }
+}

common/src/eu/e99/svc/io/Writer.java

@@ -0,0 +1,43 @@
+package eu.e99.svc.io;
+
+import java.io.DataOutputStream;
+import java.io.IOException;
+import java.io.OutputStream;
+import java.nio.charset.StandardCharsets;
+import java.util.UUID;
+
+public class Writer {
+
+    private final DataOutputStream out;
+
+    public Writer(OutputStream out) {
+        this.out = new DataOutputStream(out);
+    }
+
+    public void writeInt(int i) throws IOException {
+        this.out.writeInt(i);
+    }
+
+    public void writeLong(long l) throws IOException {
+        this.out.writeLong(l);
+    }
+
+    public void writeBool(boolean bool) throws IOException {
+        this.out.writeBoolean(bool);
+    }
+
+    public void writeString(String string) throws IOException {
+        byte[] bytes = string.getBytes(StandardCharsets.UTF_8);
+        this.writeByteArray(bytes);
+    }
+
+    public void writeByteArray(byte[] bytes) throws IOException {
+        this.writeInt(bytes.length);
+        this.out.write(bytes);
+    }
+
+    public void writeUUID(UUID uuid) throws IOException {
+        this.writeLong(uuid.getMostSignificantBits());
+        this.writeLong(uuid.getLeastSignificantBits());
+    }
+}

common/src/eu/e99/svc/packet/AuthRequestPacket.java

@@ -0,0 +1,22 @@
+package eu.e99.svc.packet;
+
+import eu.e99.svc.io.BinaryMessage;
+import eu.e99.svc.io.Reader;
+import eu.e99.svc.io.Writer;
+
+import java.io.IOException;
+
+public class AuthRequestPacket implements BinaryMessage {
+
+    public String serverId;
+
+    @Override
+    public void read(Reader reader) throws IOException {
+        this.serverId = reader.readString();
+    }
+
+    @Override
+    public void write(Writer writer) throws IOException {
+        writer.writeString(this.serverId);
+    }
+}

common/src/eu/e99/svc/packet/AuthResponsePacket.java

@@ -0,0 +1,22 @@
+package eu.e99.svc.packet;
+
+import eu.e99.svc.io.BinaryMessage;
+import eu.e99.svc.io.Reader;
+import eu.e99.svc.io.Writer;
+
+import java.io.IOException;
+
+public class AuthResponsePacket implements BinaryMessage {
+
+    public String username;
+
+    @Override
+    public void read(Reader reader) throws IOException {
+        this.username = reader.readString();
+    }
+
+    @Override
+    public void write(Writer writer) throws IOException {
+        writer.writeString(this.username);
+    }
+}

common/src/eu/e99/svc/packet/AuthSuccessPacket.java

@@ -0,0 +1,20 @@
+package eu.e99.svc.packet;
+
+import eu.e99.svc.io.BinaryMessage;
+import eu.e99.svc.io.Reader;
+import eu.e99.svc.io.Writer;
+
+import java.io.IOException;
+
+public class AuthSuccessPacket implements BinaryMessage {
+
+    @Override
+    public void read(Reader reader) throws IOException {
+
+    }
+
+    @Override
+    public void write(Writer writer) throws IOException {
+
+    }
+}

common/src/eu/e99/svc/packet/ClientHelloPacket.java

@@ -0,0 +1,22 @@
+package eu.e99.svc.packet;
+
+import eu.e99.svc.io.BinaryMessage;
+import eu.e99.svc.io.Reader;
+import eu.e99.svc.io.Writer;
+
+import java.io.IOException;
+
+public class ClientHelloPacket implements BinaryMessage {
+
+    public int version;
+
+    @Override
+    public void read(Reader reader) throws IOException {
+        this.version = reader.readInt();
+    }
+
+    @Override
+    public void write(Writer writer) throws IOException {
+        writer.writeInt(this.version);
+    }
+}

common/src/eu/e99/svc/packet/DisconnectPacket.java

@@ -0,0 +1,22 @@
+package eu.e99.svc.packet;
+
+import eu.e99.svc.io.BinaryMessage;
+import eu.e99.svc.io.Reader;
+import eu.e99.svc.io.Writer;
+
+import java.io.IOException;
+
+public class DisconnectPacket implements BinaryMessage {
+
+    public String reason;
+
+    @Override
+    public void read(Reader reader) throws IOException {
+        this.reason = reader.readString();
+    }
+
+    @Override
+    public void write(Writer writer) throws IOException {
+        writer.writeString(this.reason);
+    }
+}

common/src/eu/e99/svc/packet/MessagePacket.java

@@ -0,0 +1,26 @@
+package eu.e99.svc.packet;
+
+import eu.e99.svc.io.BinaryMessage;
+import eu.e99.svc.io.Reader;
+import eu.e99.svc.io.Writer;
+
+import java.io.IOException;
+import java.util.UUID;
+
+public class MessagePacket implements BinaryMessage {
+
+    public UUID player;
+    public byte[] payload;
+
+    @Override
+    public void read(Reader reader) throws IOException {
+        this.player = reader.readUUID();
+        this.payload = reader.readByteArray();
+    }
+
+    @Override
+    public void write(Writer writer) throws IOException {
+        writer.writeUUID(this.player);
+        writer.writeByteArray(this.payload);
+    }
+}

gradle/wrapper/gradle-wrapper.properties

@@ -0,0 +1 @@
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.11-bin.zip

gradlew

@@ -0,0 +1,176 @@
+#!/usr/bin/env sh
+
+##############################################################################
+##
+##  Gradle start up script for UN*X
+##
+##############################################################################
+
+# Attempt to set APP_HOME
+# Resolve links: $0 may be a link
+PRG="$0"
+# Need this for relative symlinks.
+while [ -h "$PRG" ] ; do
+    ls=`ls -ld "$PRG"`
+    link=`expr "$ls" : '.*-> \(.*\)$'`
+    if expr "$link" : '/.*' > /dev/null; then
+        PRG="$link"
+    else
+        PRG=`dirname "$PRG"`"/$link"
+    fi
+done
+SAVED="`pwd`"
+cd "`dirname \"$PRG\"`/" >/dev/null
+APP_HOME="`pwd -P`"
+cd "$SAVED" >/dev/null
+
+APP_NAME="Gradle"
+APP_BASE_NAME=`basename "$0"`
+
+# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+DEFAULT_JVM_OPTS=""
+
+# Use the maximum available, or set MAX_FD != -1 to use that value.
+MAX_FD="maximum"
+
+warn () {
+    echo "$*"
+}
+
+die () {
+    echo
+    echo "$*"
+    echo
+    exit 1
+}
+
+# OS specific support (must be 'true' or 'false').
+cygwin=false
+msys=false
+darwin=false
+nonstop=false
+case "`uname`" in
+  CYGWIN* )
+    cygwin=true
+    ;;
+  Darwin* )
+    darwin=true
+    ;;
+  MINGW* )
+    msys=true
+    ;;
+  NONSTOP* )
+    nonstop=true
+    ;;
+esac
+
+CLASSPATH=$APP_HOME/gradle/wrapper/gradle-wrapper.jar
+
+# Determine the Java command to use to start the JVM.
+if [ -n "$JAVA_HOME" ] ; then
+    if [ -x "$JAVA_HOME/jre/sh/java" ] ; then
+        # IBM's JDK on AIX uses strange locations for the executables
+        JAVACMD="$JAVA_HOME/jre/sh/java"
+    else
+        JAVACMD="$JAVA_HOME/bin/java"
+    fi
+    if [ ! -x "$JAVACMD" ] ; then
+        die "ERROR: JAVA_HOME is set to an invalid directory: $JAVA_HOME
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+    fi
+else
+    JAVACMD="java"
+    which java >/dev/null 2>&1 || die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+fi
+
+# Increase the maximum file descriptors if we can.
+if [ "$cygwin" = "false" -a "$darwin" = "false" -a "$nonstop" = "false" ] ; then
+    MAX_FD_LIMIT=`ulimit -H -n`
+    if [ $? -eq 0 ] ; then
+        if [ "$MAX_FD" = "maximum" -o "$MAX_FD" = "max" ] ; then
+            MAX_FD="$MAX_FD_LIMIT"
+        fi
+        ulimit -n $MAX_FD
+        if [ $? -ne 0 ] ; then
+            warn "Could not set maximum file descriptor limit: $MAX_FD"
+        fi
+    else
+        warn "Could not query maximum file descriptor limit: $MAX_FD_LIMIT"
+    fi
+fi
+
+# For Darwin, add options to specify how the application appears in the dock
+if $darwin; then
+    GRADLE_OPTS="$GRADLE_OPTS \"-Xdock:name=$APP_NAME\" \"-Xdock:icon=$APP_HOME/media/gradle.icns\""
+fi
+
+# For Cygwin, switch paths to Windows format before running java
+if $cygwin ; then
+    APP_HOME=`cygpath --path --mixed "$APP_HOME"`
+    CLASSPATH=`cygpath --path --mixed "$CLASSPATH"`
+    JAVACMD=`cygpath --unix "$JAVACMD"`
+
+    # We build the pattern for arguments to be converted via cygpath
+    ROOTDIRSRAW=`find -L / -maxdepth 1 -mindepth 1 -type d 2>/dev/null`
+    SEP=""
+    for dir in $ROOTDIRSRAW ; do
+        ROOTDIRS="$ROOTDIRS$SEP$dir"
+        SEP="|"
+    done
+    OURCYGPATTERN="(^($ROOTDIRS))"
+    # Add a user-defined pattern to the cygpath arguments
+    if [ "$GRADLE_CYGPATTERN" != "" ] ; then
+        OURCYGPATTERN="$OURCYGPATTERN|($GRADLE_CYGPATTERN)"
+    fi
+    # Now convert the arguments - kludge to limit ourselves to /bin/sh
+    i=0
+    for arg in "$@" ; do
+        CHECK=`echo "$arg"|egrep -c "$OURCYGPATTERN" -`
+        CHECK2=`echo "$arg"|egrep -c "^-"`                                 ### Determine if an option
+
+        if [ $CHECK -ne 0 ] && [ $CHECK2 -eq 0 ] ; then                    ### Added a condition
+            eval `echo args$i`=`cygpath --path --ignore --mixed "$arg"`
+        else
+            eval `echo args$i`="\"$arg\""
+        fi
+        i=$((i+1))
+    done
+    case $i in
+        (0) set -- ;;
+        (1) set -- "$args0" ;;
+        (2) set -- "$args0" "$args1" ;;
+        (3) set -- "$args0" "$args1" "$args2" ;;
+        (4) set -- "$args0" "$args1" "$args2" "$args3" ;;
+        (5) set -- "$args0" "$args1" "$args2" "$args3" "$args4" ;;
+        (6) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" ;;
+        (7) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" ;;
+        (8) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" ;;
+        (9) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" "$args8" ;;
+    esac
+fi
+
+# Escape application args
+save () {
+    for i do printf %s\\n "$i" | sed "s/'/'\\\\''/g;1s/^/'/;\$s/\$/' \\\\/" ; done
+    echo " "
+}
+APP_ARGS=$(save "$@")
+
+# Collect all arguments for the java command, following the shell quoting and substitution rules
+if $JAVACMD --add-opens java.base/java.lang=ALL-UNNAMED -version ; then
+    DEFAULT_JVM_OPTS="--add-opens java.base/java.lang=ALL-UNNAMED $DEFAULT_JVM_OPTS"
+fi
+
+eval set -- $DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS "\"-Dorg.gradle.appname=$APP_BASE_NAME\"" -classpath "\"$CLASSPATH\"" org.gradle.wrapper.GradleWrapperMain "$APP_ARGS"
+
+# by default we should be in the correct project dir, but when run from Finder on Mac, the cwd is wrong
+if [ "$(uname)" = "Darwin" ] && [ "$HOME" = "$PWD" ]; then
+  cd "$(dirname "$0")"
+fi
+
+exec "$JAVACMD" "$@"

gradlew.bat

@@ -0,0 +1,84 @@
+@if "%DEBUG%" == "" @echo off
+@rem ##########################################################################
+@rem
+@rem  Gradle startup script for Windows
+@rem
+@rem ##########################################################################
+
+@rem Set local scope for the variables with windows NT shell
+if "%OS%"=="Windows_NT" setlocal
+
+set DIRNAME=%~dp0
+if "%DIRNAME%" == "" set DIRNAME=.
+set APP_BASE_NAME=%~n0
+set APP_HOME=%DIRNAME%
+
+@rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+set DEFAULT_JVM_OPTS=
+
+@rem Find java.exe
+if defined JAVA_HOME goto findJavaFromJavaHome
+
+set JAVA_EXE=java.exe
+%JAVA_EXE% -version >NUL 2>&1
+if "%ERRORLEVEL%" == "0" goto init
+
+echo.
+echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:findJavaFromJavaHome
+set JAVA_HOME=%JAVA_HOME:"=%
+set JAVA_EXE=%JAVA_HOME%/bin/java.exe
+
+if exist "%JAVA_EXE%" goto init
+
+echo.
+echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME%
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:init
+@rem Get command-line arguments, handling Windows variants
+
+if not "%OS%" == "Windows_NT" goto win9xME_args
+
+:win9xME_args
+@rem Slurp the command line arguments.
+set CMD_LINE_ARGS=
+set _SKIP=2
+
+:win9xME_args_slurp
+if "x%~1" == "x" goto execute
+
+set CMD_LINE_ARGS=%*
+
+:execute
+@rem Setup the command line
+
+set CLASSPATH=%APP_HOME%\gradle\wrapper\gradle-wrapper.jar
+
+@rem Execute Gradle
+"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" org.gradle.wrapper.GradleWrapperMain %CMD_LINE_ARGS%
+
+:end
+@rem End local scope for the variables with windows NT shell
+if "%ERRORLEVEL%"=="0" goto mainEnd
+
+:fail
+rem Set variable GRADLE_EXIT_CONSOLE if you need the _script_ return code instead of
+rem the _cmd.exe /c_ return code!
+if  not "" == "%GRADLE_EXIT_CONSOLE%" exit 1
+exit /b 1
+
+:mainEnd
+if "%OS%"=="Windows_NT" endlocal
+
+:omega

server/build.gradle

@@ -0,0 +1,18 @@
+plugins {
+    id 'java'
+}
+
+repositories {
+    mavenCentral()
+}
+
+dependencies {
+    implementation project(':common')
+    implementation 'org.slf4j:slf4j-api:2.0.16'
+    implementation 'org.slf4j:slf4j-simple:2.0.16'
+}
+
+sourceSets {
+    main.java.srcDirs = ['src']
+    main.resources.srcDirs = ['resources']
+}

server/src/eu/e99/svc/server/Main.java

@@ -0,0 +1,65 @@
+package eu.e99.svc.server;
+
+import javax.net.ssl.KeyManagerFactory;
+import javax.net.ssl.SSLContext;
+import javax.net.ssl.SSLServerSocketFactory;
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.net.Inet4Address;
+import java.net.InetSocketAddress;
+import java.net.ServerSocket;
+import java.security.KeyStore;
+
+public class Main {
+
+    public static void main(String[] args) {
+        SSLServerSocketFactory socketFactory = createSocketFactory();
+        if (socketFactory == null) {
+            System.exit(1);
+        }
+
+        try (ServerSocket socket = socketFactory.createServerSocket()) {
+            socket.bind(new InetSocketAddress("0.0.0.0", 6969));
+
+            Server server = new Server(socket);
+            server.start();
+        } catch (IOException e) {
+            e.printStackTrace(System.out);
+        }
+    }
+
+    private static SSLServerSocketFactory createSocketFactory() {
+        try {
+            // keytool -genkeypair -keyalg RSA -keysize 2048 -validity 365 -alias mykey -keystore keystore.jks
+            String path = System.getenv("SVC_KEYSTORE_PATH");
+            if (path == null) {
+                System.out.printf("Missing SVC_KEYSTORE_PATH env variable.%n");
+                return null;
+            }
+
+            String password = System.getenv("SVC_KEYSTORE_PASSWORD");
+            if (password == null) {
+                System.out.printf("Missing SVC_KEYSTORE_PASSWORD env variable.%n");
+                return null;
+            }
+
+            KeyStore keyStore = KeyStore.getInstance("JKS");
+
+            try (FileInputStream keystoreFile = new FileInputStream(path)) {
+                keyStore.load(keystoreFile, password.toCharArray());
+            }
+
+            KeyManagerFactory managerFactory = KeyManagerFactory.getInstance("SunX509");
+            managerFactory.init(keyStore, password.toCharArray());
+
+            SSLContext context = SSLContext.getInstance("TLS");
+            context.init(managerFactory.getKeyManagers(), null, null);
+
+            return context.getServerSocketFactory();
+        } catch (Exception e) {
+            System.out.printf("Failed to create SSL Server Socket Factory.%n");
+            e.printStackTrace(System.out);
+            return null;
+        }
+    }
+}

server/src/eu/e99/svc/server/Server.java

@@ -0,0 +1,195 @@
+package eu.e99.svc.server;
+
+import eu.e99.svc.Connection;
+import eu.e99.svc.SimplerVoiceChat;
+import eu.e99.svc.auth.MojangAPI;
+import eu.e99.svc.auth.PlayerProfile;
+import eu.e99.svc.io.BinaryMessage;
+import eu.e99.svc.packet.*;
+
+import java.io.IOException;
+import java.net.ServerSocket;
+import java.net.Socket;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.UUID;
+
+public class Server {
+
+    private final ServerSocket socket;
+    private final Map<UUID, Connection> connections;
+
+    public Server(ServerSocket socket) {
+        this.socket = socket;
+        this.connections = new HashMap<>();
+    }
+
+    public void start() {
+        while (true) {
+            Thread.ofVirtual().start(() -> {
+                try (Socket client = this.socket.accept()) {
+                    synchronized (this.socket) {
+                        this.socket.notify();
+                    }
+
+                    this.handleConnection(client);
+                } catch (IOException e) {
+                    synchronized (this.socket) {
+                        this.socket.notify();
+                    }
+
+                    System.out.printf("Failed to accept client.%n");
+                    e.printStackTrace(System.out);
+                }
+            });
+
+            try {
+                synchronized (this.socket) {
+                    this.socket.wait();
+                }
+            } catch (InterruptedException e) {
+                System.out.printf("Failed to wait on server socket to accept client.%n");
+                e.printStackTrace(System.out);
+            }
+        }
+    }
+
+    private void handleConnection(Socket client) throws IOException {
+        System.out.printf("Accepted client %s.%n", client.getInetAddress());
+        Connection conn = new Connection(client);
+
+        PlayerProfile profile = this.handleHandshake(conn);
+        if (profile == null) {
+            System.out.printf("Client failed authentication.%n");
+            return;
+        }
+
+        try {
+            synchronized (this.connections) {
+                Connection existingConn = this.connections.get(profile.uuid());
+                if (existingConn != null) {
+                    existingConn.disconnect("Logged in from another location.");
+                    System.out.printf("Client %s logged in from another location.%n", profile.username());
+                }
+
+                this.connections.put(profile.uuid(), conn);
+                System.out.printf("Client %s successfully authenticated.%n", profile.username());
+            }
+
+            this.handle(conn, profile);
+        } finally {
+            synchronized (this.connections) {
+                this.connections.remove(profile.uuid());
+            }
+        }
+    }
+
+    private PlayerProfile handleHandshake(Connection conn) throws IOException {
+        /*
+        1. Client sends ClientHelloPacket
+        2. Server sends AuthRequestPacket with a random server ID
+        3. Client joins fake server ID using Mojang's session server
+        4. Client sends AuthResponsePacket with its username
+        5. Server checks if player joined the server with Mojang's session server
+        6. Server sends AuthSuccessPacket
+         */
+
+        String serverId = this.generateServerId();
+
+        while (true) {
+            BinaryMessage packet = conn.readPacket();
+
+            switch (packet) {
+                case ClientHelloPacket clientHello -> {
+                    if (clientHello.version > SimplerVoiceChat.PROTOCOL_VERSION) {
+                        System.out.printf("Refusing to accept client, outdated server.%n");
+                        conn.disconnect("Outdated server. Please downgrade the mod.");
+                        return null;
+                    }
+
+                    if (clientHello.version < SimplerVoiceChat.PROTOCOL_VERSION) {
+                        System.out.printf("Refusing to accept client, outdated client.%n");
+                        conn.disconnect("Outdated client. Please update the mode.");
+                        return null;
+                    }
+
+                    AuthRequestPacket authRequest = new AuthRequestPacket();
+                    authRequest.serverId = serverId;
+                    conn.writePacket(authRequest);
+                }
+                case AuthResponsePacket response -> {
+                    PlayerProfile profile;
+                    try {
+                        profile = MojangAPI.hasJoined(response.username, serverId);
+                    } catch (InterruptedException e) {
+                        System.out.printf("Failed to reach Mojang's authentication server.%n");
+                        e.printStackTrace(System.out);
+
+                        conn.disconnect("Mojang's authentication servers are offline. Please try again later.");
+                        return null;
+                    }
+
+                    if (profile == null) {
+                        System.out.printf("Client failed authentication.%n");
+                        conn.disconnect("Authentication failed.");
+                        return null;
+                    }
+
+                    AuthSuccessPacket success = new AuthSuccessPacket();
+                    conn.writePacket(success);
+                    return profile;
+                }
+                default -> {
+                    System.out.printf("Received unexpected packet.%n");
+                }
+            }
+        }
+    }
+
+    private void handle(Connection conn, PlayerProfile profile) throws IOException {
+        while (true) {
+            BinaryMessage packet = conn.readPacket();
+
+            switch (packet) {
+                case DisconnectPacket disconnect -> {
+                    System.out.printf("Client %s disconnected with the reason \"%s\"%n", profile.username(), disconnect.reason);
+                    return;
+                }
+                case MessagePacket message -> {
+                    Connection otherConn;
+                    synchronized (this.connections) {
+                        otherConn = this.connections.get(message.player);
+                    }
+
+                    if (otherConn == null) {
+                        // TODO: Send error to client?
+                        continue;
+                    }
+
+                    MessagePacket newMessage = new MessagePacket();
+                    newMessage.player = profile.uuid();
+                    newMessage.payload = message.payload;
+
+                    otherConn.writePacket(newMessage);
+                }
+                default -> {
+                    System.out.printf("Received unexpected packet.%n");
+                }
+            }
+        }
+    }
+
+    private String generateServerId() {
+        int length = 32;
+
+        String letters = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
+        StringBuilder builder = new StringBuilder(length);
+
+        for (int i = 0; i < length; i++) {
+            int letter = (int) (letters.length() * Math.random());
+            builder.append(letters.charAt(letter));
+        }
+
+        return builder.toString();
+    }
+}

settings.gradle

@@ -0,0 +1,15 @@
+pluginManagement {
+    repositories {
+        maven {
+            name = 'Fabric'
+            url = 'https://maven.fabricmc.net/'
+        }
+        mavenCentral()
+        gradlePluginPortal()
+    }
+}
+
+rootProject.name = 'simplervoicechat'
+include 'client-fabric'
+include 'common'
+include 'server'