From c28364c5dd4f2cff78fba1a294e0d384274be479 Mon Sep 17 00:00:00 2001
From: Camotoy <20743703+Camotoy@users.noreply.github.com>
Date: Tue, 21 Sep 2021 21:06:07 -0400
Subject: [PATCH] Prevent large ArrayLists from growing on collision checks

See #2540 - not confirmed to be resolved as we weren't able to replicate a cause for this issue but this solved the issue from artifically invoking it.
---
 .../network/session/GeyserSession.java        |  2 +-
 .../network/session/cache/PistonCache.java    |  2 +-
 .../player/BedrockMovePlayerTranslator.java   |  2 +-
 .../collision/CollisionManager.java           | 25 ++++++++++++-------
 4 files changed, 19 insertions(+), 12 deletions(-)

diff --git a/connector/src/main/java/org/geysermc/connector/network/session/GeyserSession.java b/connector/src/main/java/org/geysermc/connector/network/session/GeyserSession.java
index c9c42e756..97773458c 100644
--- a/connector/src/main/java/org/geysermc/connector/network/session/GeyserSession.java
+++ b/connector/src/main/java/org/geysermc/connector/network/session/GeyserSession.java
@@ -929,7 +929,7 @@ public class GeyserSession implements CommandSender {
             // Check to see if the player's position needs updating - a position update should be sent once every 3 seconds
             if (spawned && (System.currentTimeMillis() - lastMovementTimestamp) > 3000) {
                 // Recalculate in case something else changed position
-                Vector3d position = collisionManager.adjustBedrockPosition(playerEntity.getPosition(), playerEntity.isOnGround());
+                Vector3d position = collisionManager.adjustBedrockPosition(playerEntity.getPosition(), playerEntity.isOnGround(), false);
                 // A null return value cancels the packet
                 if (position != null) {
                     ClientPlayerPositionPacket packet = new ClientPlayerPositionPacket(playerEntity.isOnGround(),
diff --git a/connector/src/main/java/org/geysermc/connector/network/session/cache/PistonCache.java b/connector/src/main/java/org/geysermc/connector/network/session/cache/PistonCache.java
index aa929759c..a0bed9ad4 100644
--- a/connector/src/main/java/org/geysermc/connector/network/session/cache/PistonCache.java
+++ b/connector/src/main/java/org/geysermc/connector/network/session/cache/PistonCache.java
@@ -150,7 +150,7 @@ public class PistonCache {
 
         Vector3d delta = totalDisplacement.sub(playerDisplacement);
         // Check if the piston is pushing a player into collision
-        delta = session.getCollisionManager().correctPlayerMovement(delta, true);
+        delta = session.getCollisionManager().correctPlayerMovement(delta, true, false);
 
         session.getCollisionManager().getPlayerBoundingBox().translate(delta.getX(), delta.getY(), delta.getZ());
 
diff --git a/connector/src/main/java/org/geysermc/connector/network/translators/bedrock/entity/player/BedrockMovePlayerTranslator.java b/connector/src/main/java/org/geysermc/connector/network/translators/bedrock/entity/player/BedrockMovePlayerTranslator.java
index b0ab3f1e4..869af9ae6 100644
--- a/connector/src/main/java/org/geysermc/connector/network/translators/bedrock/entity/player/BedrockMovePlayerTranslator.java
+++ b/connector/src/main/java/org/geysermc/connector/network/translators/bedrock/entity/player/BedrockMovePlayerTranslator.java
@@ -97,7 +97,7 @@ public class BedrockMovePlayerTranslator extends PacketTranslator<MovePlayerPack
             }
 
             if (isValidMove(session, packet.getMode(), entity.getPosition(), packet.getPosition())) {
-                Vector3d position = session.getCollisionManager().adjustBedrockPosition(packet.getPosition(), packet.isOnGround());
+                Vector3d position = session.getCollisionManager().adjustBedrockPosition(packet.getPosition(), packet.isOnGround(), packet.getMode() == MovePlayerPacket.Mode.TELEPORT);
                 if (position != null) { // A null return value cancels the packet
                     Packet movePacket;
                     if (rotationChanged) {
diff --git a/connector/src/main/java/org/geysermc/connector/network/translators/collision/CollisionManager.java b/connector/src/main/java/org/geysermc/connector/network/translators/collision/CollisionManager.java
index 943682f5c..9b3641566 100644
--- a/connector/src/main/java/org/geysermc/connector/network/translators/collision/CollisionManager.java
+++ b/connector/src/main/java/org/geysermc/connector/network/translators/collision/CollisionManager.java
@@ -135,7 +135,7 @@ public class CollisionManager {
      * @param onGround whether the Bedrock player is on the ground
      * @return the position to send to the Java server, or null to cancel sending the packet
      */
-    public Vector3d adjustBedrockPosition(Vector3f bedrockPosition, boolean onGround) {
+    public Vector3d adjustBedrockPosition(Vector3f bedrockPosition, boolean onGround, boolean teleported) {
         PistonCache pistonCache = session.getPistonCache();
         // Bedrock clients tend to fall off of honey blocks, so we need to teleport them to the new position
         if (pistonCache.isPlayerAttachedToHoney()) {
@@ -150,7 +150,7 @@ public class CollisionManager {
 
         Vector3d startingPos = playerBoundingBox.getBottomCenter();
         Vector3d movement = position.sub(startingPos);
-        Vector3d adjustedMovement = correctPlayerMovement(movement, false);
+        Vector3d adjustedMovement = correctPlayerMovement(movement, false, teleported);
         playerBoundingBox.translate(adjustedMovement.getX(), adjustedMovement.getY(), adjustedMovement.getZ());
         playerBoundingBox.translate(pistonCache.getPlayerMotion().getX(), pistonCache.getPlayerMotion().getY(), pistonCache.getPlayerMotion().getZ());
         // Correct player position
@@ -211,17 +211,22 @@ public class CollisionManager {
         // Expand volume by 1 in each direction to include moving blocks
         double pistonExpand = session.getPistonCache().getPistons().isEmpty() ? 0 : 1;
 
+        // Ensure sizes cannot be too large - https://github.com/GeyserMC/Geyser/issues/2540
+        double sizeX = Math.min(box.getSizeX(), 256);
+        double sizeY = Math.min(box.getSizeY(), 256);
+        double sizeZ = Math.min(box.getSizeZ(), 256);
+
         // Loop through all blocks that could collide
-        int minCollisionX = (int) Math.floor(position.getX() - ((box.getSizeX() / 2) + COLLISION_TOLERANCE + pistonExpand));
-        int maxCollisionX = (int) Math.floor(position.getX() + (box.getSizeX() / 2) + COLLISION_TOLERANCE + pistonExpand);
+        int minCollisionX = (int) Math.floor(position.getX() - ((sizeX / 2) + COLLISION_TOLERANCE + pistonExpand));
+        int maxCollisionX = (int) Math.floor(position.getX() + (sizeX / 2) + COLLISION_TOLERANCE + pistonExpand);
 
         // Y extends 0.5 blocks down because of fence hitboxes
         int minCollisionY = (int) Math.floor(position.getY() - 0.5 - COLLISION_TOLERANCE - pistonExpand / 2.0);
 
-        int maxCollisionY = (int) Math.floor(position.getY() + box.getSizeY() + pistonExpand);
+        int maxCollisionY = (int) Math.floor(position.getY() + sizeY + pistonExpand);
 
-        int minCollisionZ = (int) Math.floor(position.getZ() - ((box.getSizeZ() / 2) + COLLISION_TOLERANCE + pistonExpand));
-        int maxCollisionZ = (int) Math.floor(position.getZ() + (box.getSizeZ() / 2) + COLLISION_TOLERANCE + pistonExpand);
+        int minCollisionZ = (int) Math.floor(position.getZ() - ((sizeZ / 2) + COLLISION_TOLERANCE + pistonExpand));
+        int maxCollisionZ = (int) Math.floor(position.getZ() + (sizeZ / 2) + COLLISION_TOLERANCE + pistonExpand);
 
         for (int y = minCollisionY; y < maxCollisionY + 1; y++) {
             for (int x = minCollisionX; x < maxCollisionX + 1; x++) {
@@ -276,8 +281,10 @@ public class CollisionManager {
         return true;
     }
 
-    public Vector3d correctPlayerMovement(Vector3d movement, boolean checkWorld) {
-        if (!checkWorld && session.getPistonCache().getPistons().isEmpty()) { // There is nothing to check
+    public Vector3d correctPlayerMovement(Vector3d movement, boolean checkWorld, boolean teleported) {
+        // On the teleported check: see https://github.com/GeyserMC/Geyser/issues/2540
+        // As of this commit we don't know how it happens but we don't need to check movement here anyway in that case
+        if (teleported || (!checkWorld && session.getPistonCache().getPistons().isEmpty())) { // There is nothing to check
             return movement;
         }
         return correctMovement(movement, playerBoundingBox, session.getPlayerEntity().isOnGround(), PLAYER_STEP_UP, checkWorld);