From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Hugo Manrique <hugmanrique@gmail.com>
Date: Mon, 23 Jul 2018 14:22:26 +0200
Subject: [PATCH] Vanished players don't have rights


diff --git a/src/main/java/net/minecraft/world/entity/projectile/Projectile.java b/src/main/java/net/minecraft/world/entity/projectile/Projectile.java
index f550686d1ae45a9ecb406e999d02dba0cf022c58..273e1a6f4fd117e98732c66d9b168cab1d588127 100644
--- a/src/main/java/net/minecraft/world/entity/projectile/Projectile.java
+++ b/src/main/java/net/minecraft/world/entity/projectile/Projectile.java
@@ -211,7 +211,14 @@ public abstract class Projectile extends Entity {
         if (!entity.isSpectator() && entity.isAlive() && entity.isPickable()) {
             Entity entity1 = this.getOwner();
 
+            // Paper start - Cancel hit for vanished players
+            if (entity1 instanceof net.minecraft.server.level.ServerPlayer && entity instanceof net.minecraft.server.level.ServerPlayer) {
+                org.bukkit.entity.Player collided = (org.bukkit.entity.Player) entity.getBukkitEntity();
+                org.bukkit.entity.Player shooter = (org.bukkit.entity.Player) entity1.getBukkitEntity();
+                if (!shooter.canSee(collided)) return false;
+            }
             return entity1 == null || this.leftOwner || !entity1.isPassengerOfSameVehicle(entity);
+            // Paper end
         } else {
             return false;
         }
diff --git a/src/main/java/net/minecraft/world/item/BlockItem.java b/src/main/java/net/minecraft/world/item/BlockItem.java
index 0d7c4be0c4abefecab367334408594afa7998b5e..78cac63e5bd7c84f59b8e00ee40899be78e8cdb1 100644
--- a/src/main/java/net/minecraft/world/item/BlockItem.java
+++ b/src/main/java/net/minecraft/world/item/BlockItem.java
@@ -195,7 +195,8 @@ public class BlockItem extends Item {
         Player entityhuman = context.getPlayer();
         CollisionContext voxelshapecollision = entityhuman == null ? CollisionContext.empty() : CollisionContext.of(entityhuman);
         // CraftBukkit start - store default return
-        boolean defaultReturn = (!this.mustSurvive() || state.canSurvive(context.getLevel(), context.getClickedPos())) && context.getLevel().isUnobstructed(state, context.getClickedPos(), voxelshapecollision);
+        Level world = context.getLevel(); // Paper
+        boolean defaultReturn = (!this.mustSurvive() || state.canSurvive(context.getLevel(), context.getClickedPos())) && world.checkEntityCollision(state, entityhuman, voxelshapecollision, context.getClickedPos(), true); // Paper
         org.bukkit.entity.Player player = (context.getPlayer() instanceof ServerPlayer) ? (org.bukkit.entity.Player) context.getPlayer().getBukkitEntity() : null;
 
         BlockCanBuildEvent event = new BlockCanBuildEvent(CraftBlock.at(context.getLevel(), context.getClickedPos()), player, CraftBlockData.fromData(state), defaultReturn);
diff --git a/src/main/java/net/minecraft/world/level/Level.java b/src/main/java/net/minecraft/world/level/Level.java
index ed29841c17a4d29ca05cbd307fa474d2208f5b3f..f8058e1f54d0281863cab81e866e0aa5400bb6bd 100644
--- a/src/main/java/net/minecraft/world/level/Level.java
+++ b/src/main/java/net/minecraft/world/level/Level.java
@@ -74,6 +74,10 @@ import net.minecraft.world.level.saveddata.maps.MapItemSavedData;
 import net.minecraft.world.level.storage.LevelData;
 import net.minecraft.world.level.storage.WritableLevelData;
 import net.minecraft.world.phys.AABB;
+import net.minecraft.world.phys.shapes.BooleanOp;
+import net.minecraft.world.phys.shapes.CollisionContext;
+import net.minecraft.world.phys.shapes.Shapes;
+import net.minecraft.world.phys.shapes.VoxelShape;
 import net.minecraft.world.scores.Scoreboard;
 
 // CraftBukkit start
@@ -265,6 +269,45 @@ public abstract class Level implements LevelAccessor, AutoCloseable {
         this.tileLimiter = new org.spigotmc.TickLimiter(spigotConfig.tileMaxTickTime);
     }
 
+    // Paper start
+    // ret true if no collision
+    public final boolean checkEntityCollision(BlockState data, Entity source, CollisionContext voxelshapedcollision,
+                                              BlockPos position, boolean checkCanSee) {
+        // Copied from IWorldReader#a(IBlockData, BlockPosition, VoxelShapeCollision) & EntityAccess#a(Entity, VoxelShape)
+        VoxelShape voxelshape = data.getCollisionShape(this, position, voxelshapedcollision);
+        if (voxelshape.isEmpty()) {
+            return true;
+        }
+
+        voxelshape = voxelshape.move((double) position.getX(), (double) position.getY(), (double) position.getZ());
+        if (voxelshape.isEmpty()) {
+            return true;
+        }
+
+        List<Entity> entities = this.getEntities(null, voxelshape.bounds());
+        for (int i = 0, len = entities.size(); i < len; ++i) {
+            Entity entity = entities.get(i);
+
+            if (checkCanSee && source instanceof net.minecraft.server.level.ServerPlayer && entity instanceof net.minecraft.server.level.ServerPlayer
+                && !((net.minecraft.server.level.ServerPlayer) source).getBukkitEntity().canSee(((net.minecraft.server.level.ServerPlayer) entity).getBukkitEntity())) {
+                continue;
+            }
+
+            // !entity1.dead && entity1.i && (entity == null || !entity1.x(entity));
+            // elide the last check since vanilla calls with entity = null
+            // only we care about the source for the canSee check
+            if (entity.isRemoved() || !entity.blocksBuilding) {
+                continue;
+            }
+
+            if (Shapes.joinIsNotEmpty(voxelshape, Shapes.create(entity.getBoundingBox()), BooleanOp.AND)) {
+                return false;
+            }
+        }
+
+        return true;
+    }
+    // Paper end
     @Override
     public boolean isClientSide() {
         return this.isClientSide;
diff --git a/src/main/java/org/bukkit/craftbukkit/event/CraftEventFactory.java b/src/main/java/org/bukkit/craftbukkit/event/CraftEventFactory.java
index 63d6e3103ad7decc64c50b0f14b0049c7734b8e7..8620c065e7709bf8a366760073d58f902215d1c0 100644
--- a/src/main/java/org/bukkit/craftbukkit/event/CraftEventFactory.java
+++ b/src/main/java/org/bukkit/craftbukkit/event/CraftEventFactory.java
@@ -1258,6 +1258,14 @@ public class CraftEventFactory {
         Projectile projectile = (Projectile) entity.getBukkitEntity();
         org.bukkit.entity.Entity collided = position.getEntity().getBukkitEntity();
         com.destroystokyo.paper.event.entity.ProjectileCollideEvent event = new com.destroystokyo.paper.event.entity.ProjectileCollideEvent(projectile, collided);
+
+        if (projectile.getShooter() instanceof Player && collided instanceof Player) {
+            if (!((Player) projectile.getShooter()).canSee((Player) collided)) {
+                event.setCancelled(true);
+                return event;
+            }
+        }
+
         Bukkit.getPluginManager().callEvent(event);
         return event;
     }