From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Aikar <aikar@aikar.co>
Date: Wed, 13 May 2020 23:01:26 -0400
Subject: [PATCH] Protect Bedrock and End Portal/Frames from being destroyed

This fixes exploits that let players destroy bedrock by Pistons, explosions
and Mushrooom/Tree generation.

These blocks are designed to not be broken except by creative players/commands.
So protect them from a multitude of methods of destroying them.

A config is provided if you rather let players use these exploits, and let
them destroy the worlds End Portals and get on top of the nether easy.

diff --git a/src/main/java/net/minecraft/world/level/Level.java b/src/main/java/net/minecraft/world/level/Level.java
index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
--- a/src/main/java/net/minecraft/world/level/Level.java
+++ b/src/main/java/net/minecraft/world/level/Level.java
@@ -0,0 +0,0 @@ public abstract class Level implements LevelAccessor, AutoCloseable {
     public boolean setBlock(BlockPos pos, BlockState state, int flags, int maxUpdateDepth) {
         // CraftBukkit start - tree generation
         if (this.captureTreeGeneration) {
+            // Paper start - Protect Bedrock and End Portal/Frames from being destroyed
+            BlockState type = getBlockState(pos);
+            if (!type.isDestroyable()) return false;
+            // Paper end - Protect Bedrock and End Portal/Frames from being destroyed
             CraftBlockState blockstate = this.capturedBlockStates.get(pos);
             if (blockstate == null) {
                 blockstate = CapturedBlockState.getTreeBlockState(this, pos, flags);
diff --git a/src/main/java/net/minecraft/world/level/ServerExplosion.java b/src/main/java/net/minecraft/world/level/ServerExplosion.java
index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
--- a/src/main/java/net/minecraft/world/level/ServerExplosion.java
+++ b/src/main/java/net/minecraft/world/level/ServerExplosion.java
@@ -0,0 +0,0 @@ public class ServerExplosion implements Explosion {
                         for (float f1 = 0.3F; f > 0.0F; f -= 0.22500001F) {
                             BlockPos blockposition = BlockPos.containing(d4, d5, d6);
                             BlockState iblockdata = this.level.getBlockState(blockposition);
+                            if (!iblockdata.isDestroyable()) continue; // Paper - Protect Bedrock and End Portal/Frames from being destroyed
                             FluidState fluid = iblockdata.getFluidState(); // Paper - Perf: Optimize call to getFluid for explosions
 
                             if (!this.level.isInWorldBounds(blockposition)) {
diff --git a/src/main/java/net/minecraft/world/level/block/Block.java b/src/main/java/net/minecraft/world/level/block/Block.java
index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
--- a/src/main/java/net/minecraft/world/level/block/Block.java
+++ b/src/main/java/net/minecraft/world/level/block/Block.java
@@ -0,0 +0,0 @@ public class Block extends BlockBehaviour implements ItemLike {
     public static final int UPDATE_LIMIT = 512;
     protected final StateDefinition<Block, BlockState> stateDefinition;
     private BlockState defaultBlockState;
+    // Paper start - Protect Bedrock and End Portal/Frames from being destroyed
+    public final boolean isDestroyable() {
+        return io.papermc.paper.configuration.GlobalConfiguration.get().unsupportedSettings.allowPermanentBlockBreakExploits ||
+            this != Blocks.BARRIER &&
+            this != Blocks.BEDROCK &&
+            this != Blocks.END_PORTAL_FRAME &&
+            this != Blocks.END_PORTAL &&
+            this != Blocks.END_GATEWAY &&
+            this != Blocks.COMMAND_BLOCK &&
+            this != Blocks.REPEATING_COMMAND_BLOCK &&
+            this != Blocks.CHAIN_COMMAND_BLOCK &&
+            this != Blocks.STRUCTURE_BLOCK &&
+            this != Blocks.JIGSAW;
+    }
+    // Paper end - Protect Bedrock and End Portal/Frames from being destroyed
     @Nullable
     private Item item;
     private static final int CACHE_SIZE = 256;
diff --git a/src/main/java/net/minecraft/world/level/block/piston/PistonBaseBlock.java b/src/main/java/net/minecraft/world/level/block/piston/PistonBaseBlock.java
index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
--- a/src/main/java/net/minecraft/world/level/block/piston/PistonBaseBlock.java
+++ b/src/main/java/net/minecraft/world/level/block/piston/PistonBaseBlock.java
@@ -0,0 +0,0 @@ public class PistonBaseBlock extends DirectionalBlock {
     @Override
     protected boolean triggerEvent(BlockState state, Level world, BlockPos pos, int type, int data) {
         Direction enumdirection = (Direction) state.getValue(PistonBaseBlock.FACING);
+        // Paper start - Protect Bedrock and End Portal/Frames from being destroyed; prevent retracting when we're facing the wrong way (we were replaced before retraction could occur)
+        Direction directionQueuedAs = Direction.from3DDataValue(data & 7); // Paper - copied from below
+        if (!io.papermc.paper.configuration.GlobalConfiguration.get().unsupportedSettings.allowPermanentBlockBreakExploits && enumdirection != directionQueuedAs) {
+            return false;
+        }
+        // Paper end - Protect Bedrock and End Portal/Frames from being destroyed
         BlockState iblockdata1 = (BlockState) state.setValue(PistonBaseBlock.EXTENDED, true);
 
         if (!world.isClientSide) {
@@ -0,0 +0,0 @@ public class PistonBaseBlock extends DirectionalBlock {
             }
             // Paper end - Fix sticky pistons and BlockPistonRetractEvent
             world.setBlock(pos, iblockdata2, 20);
-            world.setBlockEntity(MovingPistonBlock.newMovingBlockEntity(pos, iblockdata2, (BlockState) this.defaultBlockState().setValue(PistonBaseBlock.FACING, Direction.from3DDataValue(data & 7)), enumdirection, false, true));
+            world.setBlockEntity(MovingPistonBlock.newMovingBlockEntity(pos, iblockdata2, (BlockState) this.defaultBlockState().setValue(PistonBaseBlock.FACING, Direction.from3DDataValue(data & 7)), enumdirection, false, true)); // Paper - Protect Bedrock and End Portal/Frames from being destroyed; diff on change
             world.blockUpdated(pos, iblockdata2.getBlock());
             iblockdata2.updateNeighbourShapes(world, pos, 2);
             if (this.isSticky) {
@@ -0,0 +0,0 @@ public class PistonBaseBlock extends DirectionalBlock {
                     }
                 }
             } else {
-                world.removeBlock(pos.relative(enumdirection), false);
+                // Paper start - Protect Bedrock and End Portal/Frames from being destroyed; fix headless pistons breaking blocks
+                BlockPos headPos = pos.relative(enumdirection);
+                if (io.papermc.paper.configuration.GlobalConfiguration.get().unsupportedSettings.allowPermanentBlockBreakExploits || world.getBlockState(headPos) == Blocks.PISTON_HEAD.defaultBlockState().setValue(FACING, enumdirection)) { // double check to make sure we're not a headless piston.
+                    world.removeBlock(headPos, false);
+                } else {
+                    ((ServerLevel) world).getChunkSource().blockChanged(headPos); // ... fix client desync
+                }
+                // Paper end - Protect Bedrock and End Portal/Frames from being destroyed
             }
 
             world.playSound((Player) null, pos, SoundEvents.PISTON_CONTRACT, SoundSource.BLOCKS, 0.5F, world.random.nextFloat() * 0.15F + 0.6F);
diff --git a/src/main/java/net/minecraft/world/level/block/state/BlockBehaviour.java b/src/main/java/net/minecraft/world/level/block/state/BlockBehaviour.java
index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
--- a/src/main/java/net/minecraft/world/level/block/state/BlockBehaviour.java
+++ b/src/main/java/net/minecraft/world/level/block/state/BlockBehaviour.java
@@ -0,0 +0,0 @@ public abstract class BlockBehaviour implements FeatureElement {
     }
 
     protected void onExplosionHit(BlockState state, ServerLevel world, BlockPos pos, Explosion explosion, BiConsumer<ItemStack, BlockPos> stackMerger) {
-        if (!state.isAir() && explosion.getBlockInteraction() != Explosion.BlockInteraction.TRIGGER_BLOCK) {
+        if (!state.isAir() && explosion.getBlockInteraction() != Explosion.BlockInteraction.TRIGGER_BLOCK && state.isDestroyable()) { // Paper - Protect Bedrock and End Portal/Frames from being destroyed
             Block block = state.getBlock();
             boolean flag = explosion.getIndirectSourceEntity() instanceof Player;
 
@@ -0,0 +0,0 @@ public abstract class BlockBehaviour implements FeatureElement {
     }
 
     protected boolean canBeReplaced(BlockState state, BlockPlaceContext context) {
-        return state.canBeReplaced() && (context.getItemInHand().isEmpty() || !context.getItemInHand().is(this.asItem()));
+        return state.canBeReplaced() && (context.getItemInHand().isEmpty() || !context.getItemInHand().is(this.asItem())) && (state.isDestroyable() || (context.getPlayer() != null && context.getPlayer().getAbilities().instabuild)); // Paper - Protect Bedrock and End Portal/Frames from being destroyed
     }
 
     protected boolean canBeReplaced(BlockState state, Fluid fluid) {
@@ -0,0 +0,0 @@ public abstract class BlockBehaviour implements FeatureElement {
             return this.legacySolid;
         }
 
+        // Paper start - Protect Bedrock and End Portal/Frames from being destroyed
+        public final boolean isDestroyable() {
+            return getBlock().isDestroyable();
+        }
+        // Paper end - Protect Bedrock and End Portal/Frames from being destroyed
+
         public boolean isValidSpawn(BlockGetter world, BlockPos pos, EntityType<?> type) {
             return this.getBlock().properties.isValidSpawn.test(this.asState(), world, pos, type);
         }
@@ -0,0 +0,0 @@ public abstract class BlockBehaviour implements FeatureElement {
         }
 
         public PushReaction getPistonPushReaction() {
-            return this.pushReaction;
+            return !this.isDestroyable() ? PushReaction.BLOCK : this.pushReaction; // Paper - Protect Bedrock and End Portal/Frames from being destroyed
         }
 
         public boolean isSolidRender() {
diff --git a/src/main/java/net/minecraft/world/level/portal/PortalForcer.java b/src/main/java/net/minecraft/world/level/portal/PortalForcer.java
index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
--- a/src/main/java/net/minecraft/world/level/portal/PortalForcer.java
+++ b/src/main/java/net/minecraft/world/level/portal/PortalForcer.java
@@ -0,0 +0,0 @@ public class PortalForcer {
         for (int j = -1; j < 3; ++j) {
             for (int k = -1; k < 4; ++k) {
                 temp.setWithOffset(pos, portalDirection.getStepX() * j + enumdirection1.getStepX() * distanceOrthogonalToPortal, k, portalDirection.getStepZ() * j + enumdirection1.getStepZ() * distanceOrthogonalToPortal);
+                // Paper start - Protect Bedrock and End Portal/Frames from being destroyed
+                if (!io.papermc.paper.configuration.GlobalConfiguration.get().unsupportedSettings.allowPermanentBlockBreakExploits) {
+                    if (!this.level.getBlockState(temp).isDestroyable()) {
+                        return false;
+                    }
+                }
+                // Paper end - Protect Bedrock and End Portal/Frames from being destroyed
                 if (k < 0 && !this.level.getBlockState(temp).isSolid()) {
                     return false;
                 }
