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 e9ae25a70c747c173ebd2e393818d205527d5314..f49dd279ba9e8970f116f956466feb072c4f8420 100644
--- a/src/main/java/net/minecraft/world/entity/projectile/Projectile.java
+++ b/src/main/java/net/minecraft/world/entity/projectile/Projectile.java
@@ -217,6 +217,15 @@ public abstract class Projectile extends Entity implements TraceableEntity {
         } else {
             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;
+                }
+            }
+            // Paper end
             return entity1 == null || this.leftOwner || !entity1.isPassengerOfSameVehicle(entity);
         }
     }
diff --git a/src/main/java/net/minecraft/world/item/BlockItem.java b/src/main/java/net/minecraft/world/item/BlockItem.java
index a6638e626600e4304a973497a39e3fac52203b16..e68b7a1b03783e4f9de24c5ae8773fc359bd2d37 100644
--- a/src/main/java/net/minecraft/world/item/BlockItem.java
+++ b/src/main/java/net/minecraft/world/item/BlockItem.java
@@ -197,7 +197,8 @@ 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 823121fdfe99db01e3e995a50dbc8e241bcebe9c..99bc511425cf079303716a5b12c913bc48ce775a 100644
--- a/src/main/java/net/minecraft/world/level/Level.java
+++ b/src/main/java/net/minecraft/world/level/Level.java
@@ -273,6 +273,45 @@ 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, net.minecraft.world.phys.shapes.CollisionContext voxelshapedcollision,
+                                              BlockPos position, boolean checkCanSee) {
+        // Copied from IWorldReader#a(IBlockData, BlockPosition, VoxelShapeCollision) & EntityAccess#a(Entity, VoxelShape)
+        net.minecraft.world.phys.shapes.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 (net.minecraft.world.phys.shapes.Shapes.joinIsNotEmpty(voxelshape, net.minecraft.world.phys.shapes.Shapes.create(entity.getBoundingBox()), net.minecraft.world.phys.shapes.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 116d3af618351cfec7dc172ba8e5170453b7226d..b77fefc9cf30fd438f557e5b56efb4c0251cb17a 100644
--- a/src/main/java/org/bukkit/craftbukkit/event/CraftEventFactory.java
+++ b/src/main/java/org/bukkit/craftbukkit/event/CraftEventFactory.java
@@ -1298,6 +1298,14 @@ 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;
     }