Use barriers instead of stone blocks for verification (#54)

* feat: replace abstract method with a java.util.function.Function

* fix: make spawn x and z position adapt to platform size

* feat: optimize/improve Fallback packet preparing

* fix: block id shifting being broken on 1.7-1.13

* fix: optimize 1.7 support in UpdateSectionBlocks packet

* style: improve codestyle of the UpdateSectionBlocks packet

* fix: use normal binary io reader for mappings instead of unlimited reader

* feat: implement universal Chat packet and add LOGIN / GAME states for better packet registry control

* feat: [wip] barrier block integration (block ids for 1.13+ are still missing)

* feat: use buffered writing more often to potentially reduce performance impact

* feat: optimize chunk sending by only flushing the packets if necessary

* refactor: setAbilitiesAndTeleport -> sendAbilitiesAndTeleport

* style: fix fields being named incorrectly

* feat: cache 1.7 empty chunk filler bytes

* feat: use barrier blocks instead of stone blocks for verification

sonar-common/src/main/java/xyz/jonesdev/sonar/common/fallback/FallbackVerificationHandler.java

@@ -78,9 +78,6 @@ public FallbackVerificationHandler(final @NotNull FallbackUser<?, ?> user,
     this.playerUuid = playerUuid;
     this.state = State.KEEP_ALIVE;
 
-    // Send LoginSuccess packet to make the client think they are joining the server
-    user.write(new ServerLoginSuccess(username, playerUuid));
-
     if (user.getProtocolVersion().compareTo(MINECRAFT_1_8) < 0) {
       // 1.7 players don't have KeepAlive packets in the login process
       sendJoinGamePacket();
@@ -110,6 +107,21 @@ private void sendJoinGamePacket() {
     user.write(getJoinPacketForVersion(user.getProtocolVersion()));
   }
 
+  private void sendAbilitiesAndTeleport() {
+    // Set the state to TELEPORT to avoid false positives
+    // and go on with the flow of the verification.
+    state = State.TELEPORT;
+    // Make sure the player is unable to fly (the player is in spectator mode)
+    user.delayedWrite(DEFAULT_ABILITIES);
+    // Generate the current teleport ID
+    expectedTeleportId = RANDOM.nextInt(Short.MAX_VALUE);
+    // Teleport the player to the spawn position
+    user.delayedWrite(new PositionLook(
+      SPAWN_X_POSITION, dynamicSpawnYPosition, SPAWN_Z_POSITION,
+      0f, 0f, expectedTeleportId, false
+    ));
+  }
+
   private void sendChunkData() {
     // Set the state to POSITION to avoid false positives
     // and go on with the flow of the verification.
@@ -123,18 +135,6 @@ private void sendChunkData() {
     user.getChannel().flush();
   }
 
-  private void setAbilitiesAndTeleport() {
-    // Make sure the player is unable to fly (the player is in spectator mode)
-    user.write(DEFAULT_ABILITIES);
-    // Generate the current teleport ID
-    expectedTeleportId = RANDOM.nextInt(Short.MAX_VALUE);
-    // Teleport the player to the spawn position
-    user.write(new PositionLook(
-      SPAWN_X_POSITION, DYNAMIC_SPAWN_Y_POSITION, SPAWN_Z_POSITION,
-      0f, 0f, expectedTeleportId, false
-    ));
-  }
-
   private static boolean validateClientLocale(final @SuppressWarnings("unused") @NotNull FallbackUser<?, ?> user,
                                               final String locale) {
     // Check the client locale by performing a simple regex check on it
@@ -254,16 +254,16 @@ public void handle(final @NotNull FallbackPacket packet) {
       // First, send an abilities packet to the client to make
       // sure the player falls even in spectator mode.
       // Then, teleport the player to the spawn position.
-      setAbilitiesAndTeleport();
+      sendAbilitiesAndTeleport();
 
       // 1.7-1.8 clients do not have a TeleportConfirm packet
       if (user.getProtocolVersion().compareTo(MINECRAFT_1_8) <= 0) {
         // Immediately send the chunk data as 1.7-1.8 can't confirm teleports
         sendChunkData();
       } else {
-        // Set the state to TELEPORT to avoid false positives
-        // and go on with the flow of the verification.
-        state = State.TELEPORT;
+        // Send all previously sent packets in one flush since we didn't flush
+        // the channel earlier when we teleported the player.
+        user.getChannel().flush();
       }
     }
 
@@ -305,7 +305,7 @@ private void handlePositionUpdate(final double x, final double y, final double z
     if (user.getProtocolVersion().compareTo(MINECRAFT_1_8) <= 0
       && expectedTeleportId != -1 // Check if the teleport ID is currently unset
       // Then, check if the position is equal to the spawn position
-      && x == SPAWN_X_POSITION && y == DYNAMIC_SPAWN_Y_POSITION && z == SPAWN_Z_POSITION) {
+      && x == SPAWN_X_POSITION && y == dynamicSpawnYPosition && z == SPAWN_Z_POSITION) {
       // Reset all values to ensure safety on teleport
       tick = 1;
       posY = -1;
@@ -332,7 +332,7 @@ private void handlePositionUpdate(final double x, final double y, final double z
         listenForMovements = true;
       }
 
-      lastY = DYNAMIC_SPAWN_Y_POSITION;
+      lastY = dynamicSpawnYPosition;
       return;
     }
 
@@ -346,7 +346,7 @@ private void handlePositionUpdate(final double x, final double y, final double z
       return;
     }
 
-    if (tick > MAX_MOVEMENT_TICK) {
+    if (tick > maxMovementTick) {
       if (!Sonar.get().getConfig().isCheckCollisions()) {
         // Checking collisions is disabled, just finish verification
         finish();
@@ -378,8 +378,8 @@ private void handlePositionUpdate(final double x, final double y, final double z
       }
     }
 
-    if (!ground && tick < MAX_PREDICTION_TICK) {
-      final double predictedY = PREPARED_MOVEMENTS[tick];
+    if (!ground && tick < maxPredictionTick) {
+      final double predictedY = preparedCachedYMotions[tick];
       final double offsetY = Math.abs(deltaY - predictedY);
 
       // Log/debug position if enabled in the configuration

sonar-common/src/main/java/xyz/jonesdev/sonar/common/fallback/protocol/FallbackPacketDecoder.java

@@ -36,7 +36,7 @@ public final class FallbackPacketDecoder extends ChannelInboundHandlerAdapter {
   public FallbackPacketDecoder(final @NotNull FallbackUser<?, ?> user,
                                final @NotNull FallbackPacketListener listener) {
     this.user = user;
-    this.registry = FallbackPacketRegistry.SONAR.getProtocolRegistry(
+    this.registry = FallbackPacketRegistry.GAME.getProtocolRegistry(
       FallbackPacketRegistry.Direction.SERVERBOUND, user.getProtocolVersion()
     );
     this.listener = listener;

sonar-common/src/main/java/xyz/jonesdev/sonar/common/fallback/protocol/FallbackPacketEncoder.java

@@ -26,13 +26,17 @@
 
 public final class FallbackPacketEncoder extends MessageToByteEncoder<FallbackPacket> {
   private final ProtocolVersion protocolVersion;
-  private final FallbackPacketRegistry.ProtocolRegistry registry;
+  private FallbackPacketRegistry.ProtocolRegistry registry;
 
   public FallbackPacketEncoder(final ProtocolVersion protocolVersion) {
     this.protocolVersion = protocolVersion;
-    this.registry = FallbackPacketRegistry.SONAR.getProtocolRegistry(
-      FallbackPacketRegistry.Direction.CLIENTBOUND, protocolVersion
-    );
+    this.registry = FallbackPacketRegistry.LOGIN
+      .getProtocolRegistry(FallbackPacketRegistry.Direction.CLIENTBOUND, protocolVersion);
+  }
+
+  public void loginSuccess() {
+    this.registry = FallbackPacketRegistry.GAME
+      .getProtocolRegistry(FallbackPacketRegistry.Direction.CLIENTBOUND, protocolVersion);
   }
 
   @Override

sonar-common/src/main/java/xyz/jonesdev/sonar/common/fallback/protocol/FallbackPacketRegistry.java

@@ -32,16 +32,17 @@
 // Most of this is taken from
 // https://github.com/PaperMC/Velocity/blob/dev/3.0.0/proxy/src/main/java/com/velocitypowered/proxy/protocol/StateRegistry.java
 public enum FallbackPacketRegistry {
-  SONAR {
+  LOGIN {
     {
       clientbound.fallback = false;
       serverbound.fallback = false;
 
-      // LOGIN
       clientbound.register(ServerLoginSuccess.class, ServerLoginSuccess::new,
         map(0x02, MINECRAFT_1_7_2, false));
-
-      // GAME
+    }
+  },
+  GAME {
+    {
       clientbound.register(JoinGame.class, JoinGame::new,
         map(0x01, MINECRAFT_1_7_2, true),
         map(0x23, MINECRAFT_1_9, true),
@@ -160,6 +161,17 @@ public enum FallbackPacketRegistry {
         map(0x2F, MINECRAFT_1_19_1, true),
         map(0x2E, MINECRAFT_1_19_3, true),
         map(0x32, MINECRAFT_1_19_4, true));
+      clientbound.register(Chat.class, Chat::new,
+        map(0x02, MINECRAFT_1_7_2, true),
+        map(0x0F, MINECRAFT_1_9, true),
+        map(0x0E, MINECRAFT_1_13, true),
+        map(0x0F, MINECRAFT_1_15, true),
+        map(0x0E, MINECRAFT_1_16, true),
+        map(0x0F, MINECRAFT_1_18_2, true),
+        map(0x5F, MINECRAFT_1_19, true),
+        map(0x62, MINECRAFT_1_19_1, true),
+        map(0x60, MINECRAFT_1_19_3, true),
+        map(0x64, MINECRAFT_1_19_4, true));
 
       serverbound.register(KeepAlive.class, KeepAlive::new,
         map(0x00, MINECRAFT_1_7_2, false),