Allow to enable online mode for player connection (#51)

.gitignore

@@ -92,6 +92,9 @@ modules.xml
 **/.settings/
 **/bin/
 
+# NetBeans Gradle#
+.nb-gradle/
+
 # Mobile Tools for Java (J2ME)
 .mtj.tmp/
 

api/src/main/java/com/velocitypowered/api/event/ResultedEvent.java

@@ -1,6 +1,7 @@
 package com.velocitypowered.api.event;
 
 import com.google.common.base.Preconditions;
+
 import net.kyori.text.Component;
 import net.kyori.text.serializer.ComponentSerializers;
 import org.checkerframework.checker.nullness.qual.NonNull;
@@ -72,7 +73,7 @@ public interface ResultedEvent<R extends ResultedEvent.Result> {
         private final boolean allowed;
         private final @Nullable Component reason;
 
-        private ComponentResult(boolean allowed, @Nullable Component reason) {
+        protected ComponentResult(boolean allowed, @Nullable Component reason) {
             this.allowed = allowed;
             this.reason = reason;
         }

api/src/main/java/com/velocitypowered/api/event/connection/PreLoginEvent.java

@@ -2,22 +2,28 @@ package com.velocitypowered.api.event.connection;
 
 import com.google.common.base.Preconditions;
 import com.velocitypowered.api.event.ResultedEvent;
+import com.velocitypowered.api.event.ResultedEvent.ComponentResult;
 import com.velocitypowered.api.proxy.InboundConnection;
+
+import net.kyori.text.Component;
+
+
 import org.checkerframework.checker.nullness.qual.NonNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * This event is fired when a player has initiated a connection with the proxy but before the proxy authenticates the
  * player with Mojang or before the player's proxy connection is fully established (for offline mode).
  */
-public class PreLoginEvent implements ResultedEvent<ResultedEvent.ComponentResult> {
+public class PreLoginEvent implements ResultedEvent<PreLoginEvent.PreLoginComponentResult> {
     private final InboundConnection connection;
     private final String username;
-    private ComponentResult result;
+    private PreLoginComponentResult result;
 
     public PreLoginEvent(InboundConnection connection, String username) {
         this.connection = Preconditions.checkNotNull(connection, "connection");
         this.username = Preconditions.checkNotNull(username, "username");
-        this.result = ComponentResult.allowed();
+        this.result = PreLoginComponentResult.allowed();
     }
 
     public InboundConnection getConnection() {
@@ -29,12 +35,12 @@ public class PreLoginEvent implements ResultedEvent<ResultedEvent.ComponentResul
     }
 
     @Override
-    public ComponentResult getResult() {
+    public PreLoginComponentResult getResult() {
         return result;
     }
 
     @Override
-    public void setResult(@NonNull ComponentResult result) {
+    public void setResult(@NonNull PreLoginComponentResult result) {
         this.result = Preconditions.checkNotNull(result, "result");
     }
 
@@ -46,4 +52,56 @@ public class PreLoginEvent implements ResultedEvent<ResultedEvent.ComponentResul
                 ", result=" + result +
                 '}';
     }
+
+    /**
+     * Represents an "allowed/allowed with online mode/denied" result with a reason allowed for denial.
+     */
+    public static class PreLoginComponentResult extends ComponentResult {
+
+        private static final PreLoginComponentResult ALLOWED = new PreLoginComponentResult((Component) null);
+        private static final PreLoginComponentResult FORCE_ONLINEMODE = new PreLoginComponentResult(true);
+
+        private final boolean onlineMode;
+        /**
+         * Allows to enable a online mode for the player connection, when Velocity running in offline mode
+         * Does not have any sense if velocity running in onlineMode;
+         * @param allowedOnlineMode if true, offline uuid will be used for player connection if Velocity run in offlineMode
+         */
+        private PreLoginComponentResult(boolean allowedOnlineMode) {
+            super(true, null);
+            this.onlineMode = allowedOnlineMode;
+        }
+
+        private PreLoginComponentResult(@Nullable Component reason) {
+            super(reason == null, reason);
+            // Don't care about this
+            this.onlineMode = false;
+        }
+
+        public boolean isOnlineModeAllowed() {
+            return this.onlineMode;
+        }
+
+        @Override
+        public String toString() {
+            if (isOnlineModeAllowed()) {
+                return "allowed with online mode";
+            }
+            
+            return super.toString();
+        }
+
+        public static PreLoginComponentResult allowed() {
+            return ALLOWED;
+        }
+
+        public static PreLoginComponentResult forceOnlineMode() {
+            return FORCE_ONLINEMODE;
+        }
+
+        public static PreLoginComponentResult denied(@NonNull Component reason) {
+            Preconditions.checkNotNull(reason, "reason");
+            return new PreLoginComponentResult(reason);
+        }
+    }
 }

api/src/main/java/com/velocitypowered/api/event/player/gameprofile/GameProfileRequestEvent.java

@@ -0,0 +1,53 @@
+package com.velocitypowered.api.event.player.gameprofile;
+
+import org.checkerframework.checker.nullness.qual.Nullable;
+
+import com.google.common.base.Preconditions;
+import com.velocitypowered.api.util.GameProfile;
+
+
+public class GameProfileRequestEvent {
+    private final String username;
+    private final GameProfile originalProfile;
+    private final boolean onlineMode;
+    private GameProfile gameProfile;
+
+    public GameProfileRequestEvent(GameProfile originalProfile, boolean onlinemode) {
+        this.originalProfile = Preconditions.checkNotNull(originalProfile, "profile");
+        this.username = originalProfile.getName();
+        this.onlineMode = onlinemode;
+    }
+
+    public String getUsername() {
+        return username;
+    }
+    
+    public GameProfile getOriginalProfile() {
+        return originalProfile;
+    }
+    
+    public boolean isOnlineMode() {
+        return onlineMode;
+    }
+    /**
+     * 
+     * @return a GameProfile, can be null
+     */
+    public GameProfile getGameProfile() {
+        return gameProfile;
+    }
+
+    public void setGameProfile(@Nullable GameProfile gameProfile) {
+        this.gameProfile = gameProfile;
+    }
+
+    @Override
+    public String toString() {
+        return "GameProfileRequestEvent{"+
+                    "username=" + username +
+                    ", gameProfile=" + gameProfile +
+                    "}";
+    }
+    
+    
+}

api/src/main/java/com/velocitypowered/api/proxy/Player.java

@@ -1,13 +1,16 @@
 package com.velocitypowered.api.proxy;
 
 import com.velocitypowered.api.command.CommandSource;
+import com.velocitypowered.api.event.connection.LoginEvent;
 import com.velocitypowered.api.proxy.messages.ChannelMessageSink;
 import com.velocitypowered.api.proxy.messages.ChannelMessageSource;
 import com.velocitypowered.api.server.ServerInfo;
+import com.velocitypowered.api.util.GameProfile.Property;
 import com.velocitypowered.api.util.MessagePosition;
 import net.kyori.text.Component;
 import org.checkerframework.checker.nullness.qual.NonNull;
 
+import java.util.List;
 import java.util.Optional;
 import java.util.UUID;
 

api/src/main/java/com/velocitypowered/api/util/GameProfile.java

@@ -25,7 +25,7 @@ public class GameProfile {
     public UUID idAsUuid() {
         return UuidUtils.fromUndashed(id);
     }
-
+    
     public String getName() {
         return name;
     }

proxy/src/main/java/com/velocitypowered/proxy/connection/client/ConnectedPlayer.java

@@ -9,12 +9,14 @@ import com.velocitypowered.api.proxy.ConnectionRequestBuilder;
 import com.velocitypowered.api.proxy.ServerConnection;
 import com.velocitypowered.api.proxy.messages.ChannelIdentifier;
 import com.velocitypowered.api.util.MessagePosition;
+import com.velocitypowered.api.util.UuidUtils;
 import com.velocitypowered.api.proxy.Player;
 import com.velocitypowered.proxy.VelocityServer;
 import com.velocitypowered.proxy.connection.MinecraftConnectionAssociation;
 import com.velocitypowered.proxy.connection.util.ConnectionMessages;
 import com.velocitypowered.proxy.connection.util.ConnectionRequestResults;
 import com.velocitypowered.api.util.GameProfile;
+import com.velocitypowered.proxy.protocol.StateRegistry;
 import com.velocitypowered.proxy.protocol.packet.Chat;
 import com.velocitypowered.proxy.connection.MinecraftConnection;
 import com.velocitypowered.proxy.connection.backend.VelocityServerConnection;
@@ -45,9 +47,9 @@ public class ConnectedPlayer implements MinecraftConnectionAssociation, Player {
 
     private static final Logger logger = LogManager.getLogger(ConnectedPlayer.class);
 
-    private final GameProfile profile;
     private final MinecraftConnection connection;
     private final InetSocketAddress virtualHost;
+    private final GameProfile profile;
     private PermissionFunction permissionFunction = null;
     private int tryIndex = 0;
     private VelocityServerConnection connectedServer;

proxy/src/main/java/com/velocitypowered/proxy/connection/client/LoginSessionHandler.java

@@ -3,11 +3,14 @@ package com.velocitypowered.proxy.connection.client;
 import com.google.common.base.Preconditions;
 import com.velocitypowered.api.event.connection.LoginEvent;
 import com.velocitypowered.api.event.connection.PreLoginEvent;
+import com.velocitypowered.api.event.connection.PreLoginEvent.PreLoginComponentResult;
 import com.velocitypowered.api.event.permission.PermissionsSetupEvent;
+import com.velocitypowered.api.event.player.gameprofile.GameProfileRequestEvent;
 import com.velocitypowered.api.proxy.InboundConnection;
 import com.velocitypowered.api.server.ServerInfo;
 import com.velocitypowered.proxy.connection.VelocityConstants;
 import com.velocitypowered.api.util.GameProfile;
+import com.velocitypowered.api.util.UuidUtils;
 import com.velocitypowered.proxy.protocol.MinecraftPacket;
 import com.velocitypowered.proxy.protocol.ProtocolConstants;
 import com.velocitypowered.proxy.protocol.StateRegistry;
@@ -37,7 +40,7 @@ public class LoginSessionHandler implements MinecraftSessionHandler {
     private static final Logger logger = LogManager.getLogger(LoginSessionHandler.class);
     private static final String MOJANG_SERVER_AUTH_URL =
             "https://sessionserver.mojang.com/session/minecraft/hasJoined?username=%s&serverId=%s&ip=%s";
-
+    
     private final MinecraftConnection inbound;
     private final InboundConnection apiInbound;
     private ServerLogin login;
@@ -97,15 +100,14 @@ public class LoginSessionHandler implements MinecraftSessionHandler {
                                 // The player disconnected after we authenticated them.
                                 return;
                             }
-
                             try {
                                 inbound.enableEncryption(decryptedSharedSecret);
                             } catch (GeneralSecurityException e) {
                                 throw new RuntimeException(e);
                             }
-
-                            GameProfile profile = VelocityServer.GSON.fromJson(profileResponse, GameProfile.class);
-                            initializePlayer(profile);
+                            
+                            initializePlayer(VelocityServer.GSON.fromJson(profileResponse, GameProfile.class), true);
+                            
                         }, inbound.getChannel().eventLoop())
                         .exceptionally(exception -> {
                             logger.error("Unable to enable encryption", exception);
@@ -125,20 +127,24 @@ public class LoginSessionHandler implements MinecraftSessionHandler {
         PreLoginEvent event = new PreLoginEvent(apiInbound, login.getUsername());
         VelocityServer.getServer().getEventManager().fire(event)
                 .thenRunAsync(() -> {
-                    if (!event.getResult().isAllowed()) {
+                    if (inbound.isClosed()) {
+                        // The player was disconnected
+                        return;
+                    }
+                    PreLoginComponentResult result = event.getResult();
+                    if (!result.isAllowed()) {
                         // The component is guaranteed to be provided if the connection was denied.
                         inbound.closeWith(Disconnect.create(event.getResult().getReason().get()));
                         return;
                     }
-
-                    if (VelocityServer.getServer().getConfiguration().isOnlineMode()) {
+                    
+                    if (VelocityServer.getServer().getConfiguration().isOnlineMode() || result.isOnlineModeAllowed()) {
                         // Request encryption.
                         EncryptionRequest request = generateRequest();
                         this.verify = Arrays.copyOf(request.getVerifyToken(), 4);
                         inbound.write(request);
                     } else {
-                        // Offline-mode, don't try to request encryption.
-                        initializePlayer(GameProfile.forOfflinePlayer(login.getUsername()));
+                        initializePlayer(GameProfile.forOfflinePlayer(login.getUsername()), false);
                     }
                 }, inbound.getChannel().eventLoop());
     }
@@ -153,28 +159,38 @@ public class LoginSessionHandler implements MinecraftSessionHandler {
         return request;
     }
 
-    private void initializePlayer(GameProfile profile) {
-        // Initiate a regular connection and move over to it.
-        ConnectedPlayer player = new ConnectedPlayer(profile, inbound, apiInbound.getVirtualHost().orElse(null));
+    private void initializePlayer(GameProfile profile, boolean onlineMode) {
 
-        // load permissions first
-        VelocityServer.getServer().getEventManager().fire(new PermissionsSetupEvent(player, ConnectedPlayer.DEFAULT_PERMISSIONS))
-                .thenCompose(event -> {
-                    // wait for permissions to load, then set the players permission function
-                    player.setPermissionFunction(event.createFunction(player));
-                    // then call & wait for the login event
-                    return VelocityServer.getServer().getEventManager().fire(new LoginEvent(player));
-                })
-                // then complete the connection
-                .thenAcceptAsync(event -> {
-                    if (!event.getResult().isAllowed()) {
-                        // The component is guaranteed to be provided if the connection was denied.
-                        inbound.closeWith(Disconnect.create(event.getResult().getReason().get()));
-                        return;
-                    }
+        GameProfileRequestEvent profileRequestEvent = new GameProfileRequestEvent(profile, onlineMode);
+
+        VelocityServer.getServer().getEventManager().fire(profileRequestEvent).thenCompose(profileEvent -> {
+            // Initiate a regular connection and move over to it.
+            ConnectedPlayer player = new ConnectedPlayer(profileEvent.getGameProfile() == null ? profile : profileEvent.getGameProfile(),
+                        inbound, apiInbound.getVirtualHost().orElse(null));
+
+            return VelocityServer.getServer().getEventManager().fire(new PermissionsSetupEvent(player, ConnectedPlayer.DEFAULT_PERMISSIONS))
+                        .thenCompose(event -> {
+                            // wait for permissions to load, then set the players permission function
+                            player.setPermissionFunction(event.createFunction(player));
+                            // then call & wait for the login event
+                            return VelocityServer.getServer().getEventManager().fire(new LoginEvent(player));
+                        })
+                        // then complete the connection
+                        .thenAcceptAsync(event -> {
+                            if (inbound.isClosed()) {
+                                // The player was disconnected
+                                return;
+                            }
+                            if (!event.getResult().isAllowed()) {
+                                // The component is guaranteed to be provided if the connection was denied.
+                                inbound.closeWith(Disconnect.create(event.getResult().getReason().get()));
+                                return;
+                            }
+
+                            handleProxyLogin(player);
+                        }, inbound.getChannel().eventLoop());
+        });
 
-                    handleProxyLogin(player);
-                }, inbound.getChannel().eventLoop());
     }
 
     private void handleProxyLogin(ConnectedPlayer player) {