From 0c5a1772817875126b88a1c4f58604fed54a3596 Mon Sep 17 00:00:00 2001
From: mworzala <mattheworzala@gmail.com>
Date: Sat, 2 Dec 2023 11:39:19 +0200
Subject: [PATCH] fix: ensure block placements can only happen inside the world
 border

---
 .../listener/BlockPlacementListener.java      |  7 ++-
 .../instance/BlockPlaceIntegrationTest.java   | 43 +++++++++++++++++++
 .../server/instance/BlockPlaceTest.java       | 19 --------
 3 files changed, 49 insertions(+), 20 deletions(-)
 create mode 100644 src/test/java/net/minestom/server/instance/BlockPlaceIntegrationTest.java
 delete mode 100644 src/test/java/net/minestom/server/instance/BlockPlaceTest.java

diff --git a/src/main/java/net/minestom/server/listener/BlockPlacementListener.java b/src/main/java/net/minestom/server/listener/BlockPlacementListener.java
index 8d931529e..723f0e139 100644
--- a/src/main/java/net/minestom/server/listener/BlockPlacementListener.java
+++ b/src/main/java/net/minestom/server/listener/BlockPlacementListener.java
@@ -112,9 +112,14 @@ public class BlockPlacementListener {
             }
         }
 
-        if(placementPosition.y() >= instance.getDimensionType().getMaxY()
+        if (placementPosition.y() >= instance.getDimensionType().getMaxY()
                 || placementPosition.y() <= instance.getDimensionType().getMinY()) return;
 
+        // Ensure that the final placement position is inside the world border.
+        if (!instance.getWorldBorder().isInside(placementPosition)) {
+            canPlaceBlock = false;
+        }
+
         if (!canPlaceBlock) {
             // Send a block change with the real block in the instance to keep the client in sync,
             // using refreshChunk results in the client not being in sync
diff --git a/src/test/java/net/minestom/server/instance/BlockPlaceIntegrationTest.java b/src/test/java/net/minestom/server/instance/BlockPlaceIntegrationTest.java
new file mode 100644
index 000000000..9a64a0eda
--- /dev/null
+++ b/src/test/java/net/minestom/server/instance/BlockPlaceIntegrationTest.java
@@ -0,0 +1,43 @@
+package net.minestom.server.instance;
+
+import net.minestom.server.coordinate.Pos;
+import net.minestom.server.entity.Player;
+import net.minestom.server.instance.block.Block;
+import net.minestom.server.instance.block.BlockFace;
+import net.minestom.server.item.ItemStack;
+import net.minestom.server.item.Material;
+import net.minestom.server.listener.BlockPlacementListener;
+import net.minestom.server.network.packet.client.play.ClientPlayerBlockPlacementPacket;
+import net.minestom.testing.Env;
+import net.minestom.testing.EnvTest;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+@EnvTest
+public class BlockPlaceIntegrationTest {
+
+    @Test
+    void testPlacementOutOfLimit(Env env) {
+        Instance instance = env.createFlatInstance();
+        assertDoesNotThrow(() -> instance.setBlock(0, instance.getDimensionType().getMaxY() + 1, 0, Block.STONE));
+        assertDoesNotThrow(() -> instance.setBlock(0, instance.getDimensionType().getMinY() - 1, 0, Block.STONE));
+    }
+
+    @Test
+    void testPlacementOutOfBorder(Env env) {
+        Instance instance = env.createFlatInstance();
+        instance.getWorldBorder().setDiameter(1);
+        var player = env.createPlayer(instance, new Pos(0, 40, 0));
+        player.setItemInHand(Player.Hand.MAIN, ItemStack.of(Material.STONE, 5));
+
+        // Should be air, then we place (this is outside the border)
+        assertEquals(Block.AIR, instance.getBlock(3, 40, 0));
+        var placePacket = new ClientPlayerBlockPlacementPacket(Player.Hand.MAIN, new Pos(3, 39, 0), BlockFace.TOP, 0.5f, 0.5f, 0.5f, false, 1);
+        BlockPlacementListener.listener(placePacket, player);
+
+        // Should still be air
+        var placedBlock = instance.getBlock(3, 40, 0);
+        assertEquals(Block.AIR, placedBlock);
+    }
+}
diff --git a/src/test/java/net/minestom/server/instance/BlockPlaceTest.java b/src/test/java/net/minestom/server/instance/BlockPlaceTest.java
deleted file mode 100644
index 01dfa9848..000000000
--- a/src/test/java/net/minestom/server/instance/BlockPlaceTest.java
+++ /dev/null
@@ -1,19 +0,0 @@
-package net.minestom.server.instance;
-
-import net.minestom.server.instance.block.Block;
-import net.minestom.testing.Env;
-import net.minestom.testing.EnvTest;
-import org.junit.jupiter.api.Test;
-
-import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
-
-@EnvTest
-public class BlockPlaceTest {
-
-    @Test
-    void testPlacementOutOfLimit(Env env) {
-        Instance instance = env.createFlatInstance();
-        assertDoesNotThrow(() -> instance.setBlock(0, instance.getDimensionType().getMaxY() + 1, 0, Block.STONE));
-        assertDoesNotThrow(() -> instance.setBlock(0, instance.getDimensionType().getMinY() - 1, 0, Block.STONE));
-    }
-}