Bump version to 1.97.1

Plan here is to release 1.98 for 1.16.x and 1.17.x and 1.97.1 for
1.15.x. However, will let this sit for a few days while I sort out 1.98
and the 1.17 port just in case any more bugs pop up.

.github/workflows/make-doc.yml

@@ -3,7 +3,7 @@ name: Build documentation
 on:
   push:
     branches:
-    - mc-1.15.x
+    - mc-1.16.x
 
 jobs:
   make_doc:

build.gradle

@@ -472,11 +472,12 @@ tasks.register('publishModrinth', TaskModrinthUpload.class).configure {
         project.hasProperty('modrinthApiKey')
     }
 
-    token = project.hasProperty('curseForgeApiKey')
+    token = project.hasProperty('modrinthApiKey') ? project.getProperty('modrinthApiKey') : ''
     projectId = 'gu7yAYhd'
-    versionNumber = project.mod_version
+    versionNumber = "${project.mc_version}-${project.mod_version}"
     uploadFile = jar
     addGameVersion(project.mc_version)
+    changelog = "Release notes can be found on the [GitHub repository](https://github.com/SquidDev-CC/CC-Tweaked/releases/tag/v${mc_version}-${mod_version})."
     addLoader('forge')
 }
 
@@ -546,7 +547,7 @@ githubRelease {
     tagName "v${mc_version}-${mod_version}"
     releaseName "[${mc_version}] ${mod_version}"
     body.set(project.provider({
-        "## " + new File(projectDir, "src/main/resources/data/computercraft/lua/rom/help/whatsnew.txt")
+        "## " + new File(projectDir, "src/main/resources/data/computercraft/lua/rom/help/whatsnew.md")
             .readLines()
             .takeWhile { it != 'Type "help changelog" to see the full version history.' }
             .join("\n").trim()

gradle.properties

@@ -1,5 +1,5 @@
 # Mod properties
-mod_version=1.97.0
+mod_version=1.97.1
 
 # Minecraft properties (update mods.toml when changing)
 mc_version=1.15.2

src/main/java/dan200/computercraft/ComputerCraft.java

@@ -52,6 +52,8 @@ public final class ComputerCraft
 
     public static int httpMaxRequests = 16;
     public static int httpMaxWebsockets = 4;
+    public static int httpDownloadBandwidth = 32 * 1024 * 1024;
+    public static int httpUploadBandwidth = 32 * 1024 * 1024;
 
     public static boolean enableCommandBlock = false;
     public static int modemRange = 64;

src/main/java/dan200/computercraft/client/gui/GuiTurtle.java

@@ -55,9 +55,6 @@ public class GuiTurtle extends ComputerScreenBase<ContainerTurtle>
         minecraft.getTextureManager().bind( advanced ? BACKGROUND_ADVANCED : BACKGROUND_NORMAL );
         blit( leftPos + ComputerSidebar.WIDTH, topPos, 0, 0, TEX_WIDTH, TEX_HEIGHT );
 
-        minecraft.getTextureManager().bind( advanced ? ComputerBorderRenderer.BACKGROUND_ADVANCED : ComputerBorderRenderer.BACKGROUND_NORMAL );
-        ComputerSidebar.renderBackground( leftPos, topPos + sidebarYOffset );
-
         int slot = getMenu().getSelectedSlot();
         if( slot >= 0 )
         {
@@ -69,5 +66,8 @@ public class GuiTurtle extends ComputerScreenBase<ContainerTurtle>
                 0, 217, 24, 24
             );
         }
+
+        minecraft.getTextureManager().bind( advanced ? ComputerBorderRenderer.BACKGROUND_ADVANCED : ComputerBorderRenderer.BACKGROUND_NORMAL );
+        ComputerSidebar.renderBackground( leftPos, topPos + sidebarYOffset );
     }
 }

src/main/java/dan200/computercraft/core/apis/IAPIEnvironment.java

@@ -62,6 +62,7 @@ public interface IAPIEnvironment
     @Nullable
     IPeripheral getPeripheral( ComputerSide side );
 
+    @Nullable
     String getLabel();
 
     void setLabel( @Nullable String label );

src/main/java/dan200/computercraft/core/apis/http/NetworkUtils.java

@@ -20,6 +20,8 @@ import io.netty.handler.codec.http.websocketx.WebSocketHandshakeException;
 import io.netty.handler.ssl.SslContext;
 import io.netty.handler.ssl.SslContextBuilder;
 import io.netty.handler.timeout.ReadTimeoutException;
+import io.netty.handler.traffic.AbstractTrafficShapingHandler;
+import io.netty.handler.traffic.GlobalTrafficShapingHandler;
 
 import javax.annotation.Nonnull;
 import javax.net.ssl.SSLException;
@@ -28,9 +30,7 @@ import javax.net.ssl.TrustManagerFactory;
 import java.net.InetSocketAddress;
 import java.net.URI;
 import java.security.KeyStore;
-import java.util.concurrent.ExecutorService;
-import java.util.concurrent.SynchronousQueue;
-import java.util.concurrent.ThreadPoolExecutor;
+import java.util.concurrent.ScheduledThreadPoolExecutor;
 import java.util.concurrent.TimeUnit;
 
 /**
@@ -38,10 +38,8 @@ import java.util.concurrent.TimeUnit;
  */
 public final class NetworkUtils
 {
-    public static final ExecutorService EXECUTOR = new ThreadPoolExecutor(
-        4, Integer.MAX_VALUE,
-        60L, TimeUnit.SECONDS,
-        new SynchronousQueue<>(),
+    public static final ScheduledThreadPoolExecutor EXECUTOR = new ScheduledThreadPoolExecutor(
+        4,
         ThreadUtils.builder( "Network" )
             .setPriority( Thread.MIN_PRIORITY + (Thread.NORM_PRIORITY - Thread.MIN_PRIORITY) / 2 )
             .build()
@@ -52,6 +50,15 @@ public final class NetworkUtils
         .build()
     );
 
+    public static final AbstractTrafficShapingHandler SHAPING_HANDLER = new GlobalTrafficShapingHandler(
+        EXECUTOR, ComputerCraft.httpUploadBandwidth, ComputerCraft.httpDownloadBandwidth
+    );
+
+    static
+    {
+        EXECUTOR.setKeepAliveTime( 60, TimeUnit.SECONDS );
+    }
+
     private NetworkUtils()
     {
     }
@@ -107,6 +114,16 @@ public final class NetworkUtils
         }
     }
 
+    public static void reloadConfig()
+    {
+        SHAPING_HANDLER.configure( ComputerCraft.httpUploadBandwidth, ComputerCraft.httpDownloadBandwidth );
+    }
+
+    public static void reset()
+    {
+        SHAPING_HANDLER.trafficCounter().resetCumulativeTime();
+    }
+
     /**
      * Create a {@link InetSocketAddress} from a {@link java.net.URI}.
      *

src/main/java/dan200/computercraft/core/apis/http/request/HttpRequest.java

@@ -167,6 +167,7 @@ public class HttpRequest extends Resource<HttpRequest>
                         }
 
                         ChannelPipeline p = ch.pipeline();
+                        p.addLast( NetworkUtils.SHAPING_HANDLER );
                         if( sslContext != null )
                         {
                             p.addLast( sslContext.newHandler( ch.alloc(), uri.getHost(), socketAddress.getPort() ) );

src/main/java/dan200/computercraft/core/apis/http/websocket/Websocket.java

@@ -28,7 +28,6 @@ import io.netty.handler.codec.http.HttpObjectAggregator;
 import io.netty.handler.codec.http.websocketx.WebSocketClientHandshaker;
 import io.netty.handler.codec.http.websocketx.WebSocketClientHandshakerFactory;
 import io.netty.handler.codec.http.websocketx.WebSocketVersion;
-import io.netty.handler.codec.http.websocketx.extensions.compression.WebSocketClientCompressionHandler;
 import io.netty.handler.ssl.SslContext;
 
 import java.lang.ref.WeakReference;
@@ -146,6 +145,7 @@ public class Websocket extends Resource<Websocket>
                     protected void initChannel( SocketChannel ch )
                     {
                         ChannelPipeline p = ch.pipeline();
+                        p.addLast( NetworkUtils.SHAPING_HANDLER );
                         if( sslContext != null )
                         {
                             p.addLast( sslContext.newHandler( ch.alloc(), uri.getHost(), socketAddress.getPort() ) );
@@ -160,7 +160,7 @@ public class Websocket extends Resource<Websocket>
                         p.addLast(
                             new HttpClientCodec(),
                             new HttpObjectAggregator( 8192 ),
-                            WebSocketClientCompressionHandler.INSTANCE,
+                            WebsocketCompressionHandler.INSTANCE,
                             new WebsocketHandler( Websocket.this, handshaker, options )
                         );
                     }

src/main/java/dan200/computercraft/core/apis/http/websocket/WebsocketCompressionHandler.java

@@ -0,0 +1,38 @@
+/*
+ * This file is part of ComputerCraft - http://www.computercraft.info
+ * Copyright Daniel Ratcliffe, 2011-2021. Do not distribute without permission.
+ * Send enquiries to dratcliffe@gmail.com
+ */
+package dan200.computercraft.core.apis.http.websocket;
+
+import io.netty.channel.ChannelHandler;
+import io.netty.handler.codec.compression.ZlibCodecFactory;
+import io.netty.handler.codec.http.websocketx.extensions.WebSocketClientExtensionHandler;
+import io.netty.handler.codec.http.websocketx.extensions.compression.DeflateFrameClientExtensionHandshaker;
+import io.netty.handler.codec.http.websocketx.extensions.compression.PerMessageDeflateClientExtensionHandshaker;
+import io.netty.handler.codec.http.websocketx.extensions.compression.WebSocketClientCompressionHandler;
+
+import static io.netty.handler.codec.http.websocketx.extensions.compression.PerMessageDeflateServerExtensionHandshaker.MAX_WINDOW_SIZE;
+
+/**
+ * An alternative to {@link WebSocketClientCompressionHandler} which supports the {@literal client_no_context_takeover}
+ * extension. Makes CC <em>slightly</em> more flexible.
+ */
+@ChannelHandler.Sharable
+final class WebsocketCompressionHandler extends WebSocketClientExtensionHandler
+{
+    public static final WebsocketCompressionHandler INSTANCE = new WebsocketCompressionHandler();
+
+    private WebsocketCompressionHandler()
+    {
+        super(
+            new PerMessageDeflateClientExtensionHandshaker(
+                6, ZlibCodecFactory.isSupportingWindowSizeAndMemLevel(), MAX_WINDOW_SIZE,
+                true, false
+            ),
+            new DeflateFrameClientExtensionHandshaker( false ),
+            new DeflateFrameClientExtensionHandshaker( true )
+        );
+
+    }
+}

src/main/java/dan200/computercraft/shared/CommonHooks.java

@@ -6,6 +6,7 @@
 package dan200.computercraft.shared;
 
 import dan200.computercraft.ComputerCraft;
+import dan200.computercraft.core.apis.http.NetworkUtils;
 import dan200.computercraft.core.computer.MainThread;
 import dan200.computercraft.core.tracking.Tracking;
 import dan200.computercraft.shared.command.CommandComputerCraft;
@@ -83,6 +84,7 @@ public final class CommonHooks
         ComputerCraft.serverComputerRegistry.reset();
         WirelessNetwork.resetNetworks();
         Tracking.reset();
+        NetworkUtils.reset();
     }
 
     @SubscribeEvent
@@ -91,6 +93,7 @@ public final class CommonHooks
         ComputerCraft.serverComputerRegistry.reset();
         WirelessNetwork.resetNetworks();
         Tracking.reset();
+        NetworkUtils.reset();
     }
 
     public static final ResourceLocation LOOT_TREASURE_DISK = new ResourceLocation( ComputerCraft.MOD_ID, "treasure_disk" );

src/main/java/dan200/computercraft/shared/Config.java

@@ -12,6 +12,7 @@ import com.google.common.base.CaseFormat;
 import com.google.common.base.Converter;
 import dan200.computercraft.ComputerCraft;
 import dan200.computercraft.api.turtle.event.TurtleAction;
+import dan200.computercraft.core.apis.http.NetworkUtils;
 import dan200.computercraft.core.apis.http.options.Action;
 import dan200.computercraft.core.apis.http.options.AddressRuleConfig;
 import dan200.computercraft.shared.peripheral.monitor.MonitorRenderer;
@@ -56,6 +57,9 @@ public final class Config
     private static final ConfigValue<Integer> httpMaxRequests;
     private static final ConfigValue<Integer> httpMaxWebsockets;
 
+    private static final ConfigValue<Integer> httpDownloadBandwidth;
+    private static final ConfigValue<Integer> httpUploadBandwidth;
+
     private static final ConfigValue<Boolean> commandBlockEnabled;
     private static final ConfigValue<Integer> modemRange;
     private static final ConfigValue<Integer> modemHighAltitudeRange;
@@ -187,6 +191,20 @@ public final class Config
                 .comment( "The number of websockets a computer can have open at one time. Set to 0 for unlimited." )
                 .defineInRange( "max_websockets", ComputerCraft.httpMaxWebsockets, 1, Integer.MAX_VALUE );
 
+            builder
+                .comment( "Limits bandwidth used by computers" )
+                .push( "bandwidth" );
+
+            httpDownloadBandwidth = builder
+                .comment( "The number of bytes which can be downloaded in a second. This is shared across all computers. (bytes/s)" )
+                .defineInRange( "global_download", ComputerCraft.httpDownloadBandwidth, 1, Integer.MAX_VALUE );
+
+            httpUploadBandwidth = builder
+                .comment( "The number of bytes which can be uploaded in a second. This is shared across all computers. (bytes/s)" )
+                .defineInRange( "global_upload", ComputerCraft.httpUploadBandwidth, 1, Integer.MAX_VALUE );
+
+            builder.pop();
+
             builder.pop();
         }
 
@@ -329,6 +347,8 @@ public final class Config
 
         ComputerCraft.httpMaxRequests = httpMaxRequests.get();
         ComputerCraft.httpMaxWebsockets = httpMaxWebsockets.get();
+        ComputerCraft.httpDownloadBandwidth = httpDownloadBandwidth.get();
+        NetworkUtils.reloadConfig();
 
         // Peripheral
         ComputerCraft.enableCommandBlock = commandBlockEnabled.get();

src/main/java/dan200/computercraft/shared/command/ClientCommands.java

@@ -7,11 +7,13 @@ package dan200.computercraft.shared.command;
 
 import dan200.computercraft.ComputerCraft;
 import dan200.computercraft.shared.util.IDAssigner;
+import net.minecraft.server.MinecraftServer;
 import net.minecraft.util.Util;
 import net.minecraftforge.api.distmarker.Dist;
 import net.minecraftforge.client.event.ClientChatEvent;
 import net.minecraftforge.eventbus.api.SubscribeEvent;
 import net.minecraftforge.fml.common.Mod;
+import net.minecraftforge.fml.server.ServerLifecycleHooks;
 
 import java.io.File;
 
@@ -35,6 +37,9 @@ public final class ClientCommands
         // Emulate the command on the client side
         if( event.getMessage().startsWith( OPEN_COMPUTER ) )
         {
+            MinecraftServer server = ServerLifecycleHooks.getCurrentServer();
+            if( server == null || server.isDedicatedServer() ) return;
+
             event.setCanceled( true );
 
             String idStr = event.getMessage().substring( OPEN_COMPUTER.length() ).trim();

src/main/java/dan200/computercraft/shared/network/NetworkHandler.java

@@ -21,7 +21,6 @@ import net.minecraftforge.fml.network.NetworkEvent;
 import net.minecraftforge.fml.network.NetworkRegistry;
 import net.minecraftforge.fml.network.PacketDistributor;
 import net.minecraftforge.fml.network.simple.SimpleChannel;
-import net.minecraftforge.fml.server.ServerLifecycleHooks;
 
 import java.util.function.Function;
 import java.util.function.Supplier;
@@ -68,10 +67,7 @@ public final class NetworkHandler
 
     public static void sendToAllPlayers( NetworkMessage packet )
     {
-        for( ServerPlayerEntity player : ServerLifecycleHooks.getCurrentServer().getPlayerList().getPlayers() )
-        {
-            sendToPlayer( player, packet );
-        }
+        network.send( PacketDistributor.ALL.noArg(), packet );
     }
 
     public static void sendToServer( NetworkMessage packet )

src/main/java/dan200/computercraft/shared/network/client/TerminalState.java

@@ -126,7 +126,7 @@ public class TerminalState
         if( !compress ) return buffer;
         if( compressed != null ) return compressed;
 
-        ByteBuf compressed = Unpooled.directBuffer();
+        ByteBuf compressed = Unpooled.buffer();
         OutputStream stream = null;
         try
         {

src/main/java/dan200/computercraft/shared/peripheral/diskdrive/TileDiskDrive.java

@@ -442,7 +442,7 @@ public final class TileDiskDrive extends TileGeneric implements DefaultInventory
 
     private void updateBlockState()
     {
-        if( remove ) return;
+        if( remove || level == null ) return;
 
         if( !diskStack.isEmpty() )
         {

src/main/java/dan200/computercraft/shared/peripheral/monitor/MonitorState.java

@@ -0,0 +1,52 @@
+/*
+ * This file is part of ComputerCraft - http://www.computercraft.info
+ * Copyright Daniel Ratcliffe, 2011-2021. Do not distribute without permission.
+ * Send enquiries to dratcliffe@gmail.com
+ */
+package dan200.computercraft.shared.peripheral.monitor;
+
+import javax.annotation.Nonnull;
+import javax.annotation.Nullable;
+
+final class MonitorState
+{
+    public static final MonitorState UNLOADED = new MonitorState( State.UNLOADED, null );
+    public static final MonitorState MISSING = new MonitorState( State.MISSING, null );
+
+    private final State state;
+    private final TileMonitor monitor;
+
+    private MonitorState( @Nonnull State state, @Nullable TileMonitor monitor )
+    {
+        this.state = state;
+        this.monitor = monitor;
+    }
+
+    public static MonitorState present( @Nonnull TileMonitor monitor )
+    {
+        return new MonitorState( State.PRESENT, monitor );
+    }
+
+    public boolean isPresent()
+    {
+        return state == State.PRESENT;
+    }
+
+    public boolean isMissing()
+    {
+        return state == State.MISSING;
+    }
+
+    @Nullable
+    public TileMonitor getMonitor()
+    {
+        return monitor;
+    }
+
+    enum State
+    {
+        UNLOADED,
+        MISSING,
+        PRESENT,
+    }
+}

src/main/java/dan200/computercraft/shared/peripheral/monitor/TileMonitor.java

@@ -56,6 +56,7 @@ public class TileMonitor extends TileGeneric
     private final Set<IComputerAccess> computers = new HashSet<>();
 
     private boolean needsUpdate = false;
+    private boolean needsValidating = false;
     private boolean destroyed = false;
     private boolean visiting = false;
 
@@ -78,6 +79,7 @@ public class TileMonitor extends TileGeneric
     public void onLoad()
     {
         super.onLoad();
+        needsValidating = true;
         TickScheduler.schedule( this );
     }
 
@@ -148,6 +150,12 @@ public class TileMonitor extends TileGeneric
     @Override
     public void blockTick()
     {
+        if( needsValidating )
+        {
+            needsValidating = false;
+            validate();
+        }
+
         if( needsUpdate )
         {
             needsUpdate = false;
@@ -164,7 +172,7 @@ public class TileMonitor extends TileGeneric
             {
                 for( int y = 0; y < height; y++ )
                 {
-                    TileMonitor monitor = getNeighbour( x, y );
+                    TileMonitor monitor = getNeighbour( x, y ).getMonitor();
                     if( monitor == null ) continue;
 
                     for( IComputerAccess computer : monitor.computers )
@@ -208,7 +216,7 @@ public class TileMonitor extends TileGeneric
     {
         if( serverMonitor != null ) return serverMonitor;
 
-        TileMonitor origin = getOrigin();
+        TileMonitor origin = getOrigin().getMonitor();
         if( origin == null ) return null;
 
         return serverMonitor = origin.serverMonitor;
@@ -229,7 +237,7 @@ public class TileMonitor extends TileGeneric
             {
                 for( int y = 0; y < height; y++ )
                 {
-                    TileMonitor monitor = getNeighbour( x, y );
+                    TileMonitor monitor = getNeighbour( x, y ).getMonitor();
                     if( monitor != null ) monitor.serverMonitor = serverMonitor;
                 }
             }
@@ -374,24 +382,24 @@ public class TileMonitor extends TileGeneric
         return yIndex;
     }
 
-    private TileMonitor getSimilarMonitorAt( BlockPos pos )
+    @Nonnull
+    private MonitorState getSimilarMonitorAt( BlockPos pos )
     {
-        if( pos.equals( getBlockPos() ) ) return this;
+        if( pos.equals( getBlockPos() ) ) return MonitorState.present( this );
 
-        int y = pos.getY();
         World world = getLevel();
-        if( world == null || !world.isAreaLoaded( pos, 0 ) ) return null;
+        if( world == null || !world.isAreaLoaded( pos, 0 ) ) return MonitorState.UNLOADED;
 
         TileEntity tile = world.getBlockEntity( pos );
-        if( !(tile instanceof TileMonitor) ) return null;
+        if( !(tile instanceof TileMonitor) ) return MonitorState.MISSING;
 
         TileMonitor monitor = (TileMonitor) tile;
         return !monitor.visiting && !monitor.destroyed && advanced == monitor.advanced
             && getDirection() == monitor.getDirection() && getOrientation() == monitor.getOrientation()
-            ? monitor : null;
+            ? MonitorState.present( monitor ) : MonitorState.MISSING;
     }
 
-    private TileMonitor getNeighbour( int x, int y )
+    private MonitorState getNeighbour( int x, int y )
     {
         BlockPos pos = getBlockPos();
         Direction right = getRight();
@@ -401,7 +409,7 @@ public class TileMonitor extends TileGeneric
         return getSimilarMonitorAt( pos.relative( right, xOffset ).relative( down, yOffset ) );
     }
 
-    private TileMonitor getOrigin()
+    private MonitorState getOrigin()
     {
         return getNeighbour( 0, 0 );
     }
@@ -425,7 +433,7 @@ public class TileMonitor extends TileGeneric
         {
             for( int y = 0; y < height; y++ )
             {
-                TileMonitor monitor = getNeighbour( x, y );
+                TileMonitor monitor = getNeighbour( x, y ).getMonitor();
                 if( monitor != null && monitor.peripheral != null )
                 {
                     needsTerminal = true;
@@ -453,7 +461,7 @@ public class TileMonitor extends TileGeneric
         {
             for( int y = 0; y < height; y++ )
             {
-                TileMonitor monitor = getNeighbour( x, y );
+                TileMonitor monitor = getNeighbour( x, y ).getMonitor();
                 if( monitor == null ) continue;
 
                 monitor.xIndex = x;
@@ -469,13 +477,13 @@ public class TileMonitor extends TileGeneric
 
     private boolean mergeLeft()
     {
-        TileMonitor left = getNeighbour( -1, 0 );
+        TileMonitor left = getNeighbour( -1, 0 ).getMonitor();
         if( left == null || left.yIndex != 0 || left.height != height ) return false;
 
         int width = left.width + this.width;
         if( width > ComputerCraft.monitorWidth ) return false;
 
-        TileMonitor origin = left.getOrigin();
+        TileMonitor origin = left.getOrigin().getMonitor();
         if( origin != null ) origin.resize( width, height );
         left.expand();
         return true;
@@ -483,13 +491,13 @@ public class TileMonitor extends TileGeneric
 
     private boolean mergeRight()
     {
-        TileMonitor right = getNeighbour( width, 0 );
+        TileMonitor right = getNeighbour( width, 0 ).getMonitor();
         if( right == null || right.yIndex != 0 || right.height != height ) return false;
 
         int width = this.width + right.width;
         if( width > ComputerCraft.monitorWidth ) return false;
 
-        TileMonitor origin = getOrigin();
+        TileMonitor origin = getOrigin().getMonitor();
         if( origin != null ) origin.resize( width, height );
         expand();
         return true;
@@ -497,13 +505,13 @@ public class TileMonitor extends TileGeneric
 
     private boolean mergeUp()
     {
-        TileMonitor above = getNeighbour( 0, height );
+        TileMonitor above = getNeighbour( 0, height ).getMonitor();
         if( above == null || above.xIndex != 0 || above.width != width ) return false;
 
         int height = above.height + this.height;
         if( height > ComputerCraft.monitorHeight ) return false;
 
-        TileMonitor origin = getOrigin();
+        TileMonitor origin = getOrigin().getMonitor();
         if( origin != null ) origin.resize( width, height );
         expand();
         return true;
@@ -511,13 +519,13 @@ public class TileMonitor extends TileGeneric
 
     private boolean mergeDown()
     {
-        TileMonitor below = getNeighbour( 0, -1 );
+        TileMonitor below = getNeighbour( 0, -1 ).getMonitor();
         if( below == null || below.xIndex != 0 || below.width != width ) return false;
 
         int height = this.height + below.height;
         if( height > ComputerCraft.monitorHeight ) return false;
 
-        TileMonitor origin = below.getOrigin();
+        TileMonitor origin = below.getOrigin().getMonitor();
         if( origin != null ) origin.resize( width, height );
         below.expand();
         return true;
@@ -546,22 +554,22 @@ public class TileMonitor extends TileGeneric
         visiting = true;
         if( xIndex > 0 )
         {
-            TileMonitor left = getNeighbour( xIndex - 1, yIndex );
+            TileMonitor left = getNeighbour( xIndex - 1, yIndex ).getMonitor();
             if( left != null ) left.contract();
         }
         if( xIndex + 1 < width )
         {
-            TileMonitor right = getNeighbour( xIndex + 1, yIndex );
+            TileMonitor right = getNeighbour( xIndex + 1, yIndex ).getMonitor();
             if( right != null ) right.contract();
         }
         if( yIndex > 0 )
         {
-            TileMonitor below = getNeighbour( xIndex, yIndex - 1 );
+            TileMonitor below = getNeighbour( xIndex, yIndex - 1 ).getMonitor();
             if( below != null ) below.contract();
         }
         if( yIndex + 1 < height )
         {
-            TileMonitor above = getNeighbour( xIndex, yIndex + 1 );
+            TileMonitor above = getNeighbour( xIndex, yIndex + 1 ).getMonitor();
             if( above != null ) above.contract();
         }
         visiting = false;
@@ -572,11 +580,11 @@ public class TileMonitor extends TileGeneric
         int height = this.height;
         int width = this.width;
 
-        TileMonitor origin = getOrigin();
+        TileMonitor origin = getOrigin().getMonitor();
         if( origin == null )
         {
-            TileMonitor right = width > 1 ? getNeighbour( 1, 0 ) : null;
-            TileMonitor below = height > 1 ? getNeighbour( 0, 1 ) : null;
+            TileMonitor right = width > 1 ? getNeighbour( 1, 0 ).getMonitor() : null;
+            TileMonitor below = height > 1 ? getNeighbour( 0, 1 ).getMonitor() : null;
 
             if( right != null ) right.resize( width - 1, 1 );
             if( below != null ) below.resize( width, height - 1 );
@@ -590,7 +598,7 @@ public class TileMonitor extends TileGeneric
         {
             for( int x = 0; x < width; x++ )
             {
-                TileMonitor monitor = origin.getNeighbour( x, y );
+                TileMonitor monitor = origin.getNeighbour( x, y ).getMonitor();
                 if( monitor != null ) continue;
 
                 // Decompose
@@ -606,17 +614,17 @@ public class TileMonitor extends TileGeneric
                 }
                 if( x > 0 )
                 {
-                    left = origin.getNeighbour( 0, y );
+                    left = origin.getNeighbour( 0, y ).getMonitor();
                     left.resize( x, 1 );
                 }
                 if( x + 1 < width )
                 {
-                    right = origin.getNeighbour( x + 1, y );
+                    right = origin.getNeighbour( x + 1, y ).getMonitor();
                     right.resize( width - (x + 1), 1 );
                 }
                 if( y + 1 < height )
                 {
-                    below = origin.getNeighbour( 0, y + 1 );
+                    below = origin.getNeighbour( 0, y + 1 ).getMonitor();
                     below.resize( width, height - (y + 1) );
                 }
 
@@ -630,6 +638,38 @@ public class TileMonitor extends TileGeneric
         }
     }
 
+    private boolean checkMonitorAt( int xIndex, int yIndex )
+    {
+        BlockPos pos = getBlockPos();
+        Direction right = getRight();
+        Direction down = getDown();
+
+        MonitorState state = getSimilarMonitorAt( pos.relative( right, xIndex ).relative( down, yIndex ) );
+
+        if( state.isMissing() ) return false;
+
+        TileMonitor monitor = state.getMonitor();
+        if( monitor == null ) return true;
+
+        return monitor.xIndex == xIndex && monitor.yIndex == yIndex && monitor.width == width && monitor.height == height;
+    }
+
+    private void validate()
+    {
+        if( xIndex == 0 && yIndex == 0 && width == 1 || height == 1 ) return;
+
+        if( checkMonitorAt( 0, 0 ) && checkMonitorAt( 0, height - 1 ) &&
+            checkMonitorAt( width - 1, 0 ) && checkMonitorAt( width - 1, height - 1 ) )
+        {
+            return;
+        }
+
+        // Something in our monitor is invalid. For now, let's just reset ourselves and then try to integrate ourselves
+        // later.
+        resize( 1, 1 );
+        needsUpdate = true;
+    }
+
     private void monitorTouched( float xPos, float yPos, float zPos )
     {
         XYPair pair = XYPair
@@ -657,7 +697,7 @@ public class TileMonitor extends TileGeneric
         {
             for( int x = 0; x < width; x++ )
             {
-                TileMonitor monitor = getNeighbour( x, y );
+                TileMonitor monitor = getNeighbour( x, y ).getMonitor();
                 if( monitor == null ) continue;
 
                 for( IComputerAccess computer : monitor.computers )
@@ -683,8 +723,8 @@ public class TileMonitor extends TileGeneric
     @Override
     public AxisAlignedBB getRenderBoundingBox()
     {
-        TileMonitor start = getNeighbour( 0, 0 );
-        TileMonitor end = getNeighbour( width - 1, height - 1 );
+        TileMonitor start = getNeighbour( 0, 0 ).getMonitor();
+        TileMonitor end = getNeighbour( width - 1, height - 1 ).getMonitor();
         if( start != null && end != null )
         {
             BlockPos startPos = start.getBlockPos();

src/main/java/dan200/computercraft/shared/peripheral/printer/TilePrinter.java

@@ -438,7 +438,7 @@ public final class TilePrinter extends TileGeneric implements DefaultSidedInvent
 
     private void updateBlockState( boolean top, boolean bottom )
     {
-        if( remove ) return;
+        if( remove || level == null ) return;
 
         BlockState state = getBlockState();
         if( state.getValue( BlockPrinter.TOP ) == top & state.getValue( BlockPrinter.BOTTOM ) == bottom ) return;

src/main/java/dan200/computercraft/shared/peripheral/speaker/TileSpeaker.java

@@ -47,7 +47,10 @@ public class TileSpeaker extends TileGeneric implements ITickableTileEntity
     public void setRemoved()
     {
         super.setRemoved();
-        NetworkHandler.sendToAllPlayers( new SpeakerStopClientMessage( source ) );
+        if( level != null && !level.isClientSide )
+        {
+            NetworkHandler.sendToAllPlayers( new SpeakerStopClientMessage( source ) );
+        }
     }
 
     @Nonnull

src/main/resources/data/computercraft/lua/bios.lua

@@ -681,6 +681,7 @@ if http then
     local nativeCheckURL = http.checkURL
     http.checkURLAsync = nativeCheckURL
     http.checkURL = function(_url)
+        expect(1, _url, "string")
         local ok, err = nativeCheckURL(_url)
         if not ok then return ok, err end
 

src/main/resources/data/computercraft/lua/rom/apis/rednet.lua

@@ -351,12 +351,12 @@ function run()
             -- Got a modem message, process it and add it to the rednet event queue
             local sModem, nChannel, nReplyChannel, tMessage = p1, p2, p3, p4
             if isOpen(sModem) and (nChannel == os.getComputerID() or nChannel == CHANNEL_BROADCAST) then
-                if type(tMessage) == "table" and tMessage.nMessageID then
-                    if not tReceivedMessages[tMessage.nMessageID] then
-                        tReceivedMessages[tMessage.nMessageID] = true
-                        tReceivedMessageTimeouts[os.startTimer(30)] = tMessage.nMessageID
-                        os.queueEvent("rednet_message", nReplyChannel, tMessage.message, tMessage.sProtocol)
-                    end
+                if type(tMessage) == "table" and type(tMessage.nMessageID) == "number"
+                    and tMessage.nMessageID == tMessage.nMessageID and not tReceivedMessages[tMessage.nMessageID]
+                then
+                    tReceivedMessages[tMessage.nMessageID] = true
+                    tReceivedMessageTimeouts[os.startTimer(30)] = tMessage.nMessageID
+                    os.queueEvent("rednet_message", nReplyChannel, tMessage.message, tMessage.sProtocol)
                 end
             end
 

src/main/resources/data/computercraft/lua/rom/apis/settings.lua

@@ -42,7 +42,7 @@ for _, v in ipairs(valid_types) do valid_types[v] = true end
 --    will error.
 function define(name, options)
     expect(1, name, "string")
-    expect(2, options, "table", nil)
+    expect(2, options, "table", "nil")
 
     if options then
         options = {

src/main/resources/data/computercraft/lua/rom/help/changelog.md

@@ -1,3 +1,17 @@
+# New features in CC: Tweaked 1.97.1
+* Add config options to limit total bandwidth used by the HTTP API.
+
+And several bug fixes:
+* Fix selected slot indicator not appearing in turtle interface.
+* Fix crash when printers are placed as part of world generation.
+* Fix crash when breaking a speaker on a multiplayer world.
+* Prevent issue in rednet when the message ID is NaN.
+* Fix `help` program crashing when terminal changes width.
+* Ensure monitors are well-formed when placed, preventing graphical glitches
+  when using Carry On or Quark.
+* Accept several more extensions in the websocket client.
+* Prevent `wget` crashing when given an invalid URL and no filename.
+
 # New features in CC: Tweaked 1.97.0
 
 * Update several translations (Anavrins, Jummit, Naheulf).

src/main/resources/data/computercraft/lua/rom/help/whatsnew.md

@@ -1,27 +1,15 @@
-New features in CC: Tweaked 1.97.0
-
-* Update several translations (Anavrins, Jummit, Naheulf).
-* Add button to view a computer's folder to `/computercraft dump`.
-* Allow cleaning dyed turtles in a cauldron.
-* Add scale subcommand to `monitor` program (MCJack123).
-* Add option to make `textutils.serialize` not write an indent (magiczocker10).
-* Allow comparing vectors using `==` (fatboychummy).
-* Improve HTTP error messages for SSL failures.
-* Allow `craft` program to craft unlimited items (fatboychummy).
-* Impose some limits on various command queues.
-* Add buttons to shutdown and terminate to computer GUIs.
-* Add program subcompletion to several programs (Wojbie).
-* Update the `help` program to accept and (partially) highlight markdown files.
-* Remove config option for the debug API.
-* Allow setting the subprotocol header for websockets.
+New features in CC: Tweaked 1.97.1
+* Add config options to limit total bandwidth used by the HTTP API.
 
 And several bug fixes:
-* Fix NPE when using a treasure disk when no treasure disks are available.
-* Prevent command computers discarding command ouput when certain game rules are off.
-* Fix turtles not updating peripherals when upgrades are unequipped (Ronan-H).
-* Fix computers not shutting down on fatal errors within the Lua VM.
-* Speakers now correctly stop playing when broken, and sound follows noisy turtles and pocket computers.
-* Update the `wget` to be more resiliant in the face of user-errors.
-* Fix exiting `paint` typing "e" in the shell.
+* Fix selected slot indicator not appearing in turtle interface.
+* Fix crash when printers are placed as part of world generation.
+* Fix crash when breaking a speaker on a multiplayer world.
+* Prevent issue in rednet when the message ID is NaN.
+* Fix `help` program crashing when terminal changes width.
+* Ensure monitors are well-formed when placed, preventing graphical glitches
+  when using Carry On or Quark.
+* Accept several more extensions in the websocket client.
+* Prevent `wget` crashing when given an invalid URL and no filename.
 
 Type "help changelog" to see the full version history.

src/main/resources/data/computercraft/lua/rom/motd.txt

@@ -21,3 +21,4 @@ The "equip" programs let you add upgrades to a turtle without crafting.
 You can change the color of a disk by crafting or right clicking it with dye.
 You can print on a printed page again to get multiple colors.
 Holding the Ctrl and T keys terminates the running program.
+You can drag and drop files onto an open computer to upload them.

src/main/resources/data/computercraft/lua/rom/programs/help.lua

@@ -265,7 +265,7 @@ while true do
         local new_width, new_height = term.getSize()
 
         if new_width ~= width then
-            lines = word_wrap(contents, new_width)
+            lines, fg, bg = word_wrap(contents, new_width)
             print_height = #lines
         end
 

src/main/resources/data/computercraft/lua/rom/programs/http/wget.lua

@@ -69,7 +69,7 @@ if run then
         printError(err)
     end
 else
-    local sFile = tArgs[1] or getFilename(url)
+    local sFile = tArgs[1] or getFilename(url) or url
     local sPath = shell.resolve(sFile)
     if fs.exists(sPath) then
         print("File already exists")

src/test/java/dan200/computercraft/core/apis/AsyncRunner.kt

@@ -0,0 +1,121 @@
+package dan200.computercraft.core.apis
+
+import dan200.computercraft.ComputerCraft
+import dan200.computercraft.api.lua.ILuaAPI
+import dan200.computercraft.api.lua.MethodResult
+import dan200.computercraft.api.peripheral.IPeripheral
+import dan200.computercraft.api.peripheral.IWorkMonitor
+import dan200.computercraft.core.computer.BasicEnvironment
+import dan200.computercraft.core.computer.ComputerSide
+import dan200.computercraft.core.computer.IComputerEnvironment
+import dan200.computercraft.core.filesystem.FileSystem
+import dan200.computercraft.core.terminal.Terminal
+import dan200.computercraft.core.tracking.TrackingField
+import kotlinx.coroutines.channels.Channel
+import kotlinx.coroutines.runBlocking
+import kotlinx.coroutines.withTimeout
+import kotlin.time.Duration
+import kotlin.time.ExperimentalTime
+import kotlin.time.seconds
+
+
+abstract class NullApiEnvironment : IAPIEnvironment {
+    private val computerEnv = BasicEnvironment()
+
+    override fun getComputerID(): Int = 0
+    override fun getComputerEnvironment(): IComputerEnvironment = computerEnv
+    override fun getMainThreadMonitor(): IWorkMonitor = throw IllegalStateException("Work monitor not available")
+    override fun getTerminal(): Terminal = throw IllegalStateException("Terminal not available")
+    override fun getFileSystem(): FileSystem = throw IllegalStateException("Terminal not available")
+    override fun shutdown() {}
+    override fun reboot() {}
+    override fun setOutput(side: ComputerSide?, output: Int) {}
+    override fun getOutput(side: ComputerSide?): Int = 0
+    override fun getInput(side: ComputerSide?): Int = 0
+    override fun setBundledOutput(side: ComputerSide?, output: Int) {}
+    override fun getBundledOutput(side: ComputerSide?): Int = 0
+    override fun getBundledInput(side: ComputerSide?): Int = 0
+    override fun setPeripheralChangeListener(listener: IAPIEnvironment.IPeripheralChangeListener?) {}
+    override fun getPeripheral(side: ComputerSide?): IPeripheral? = null
+    override fun getLabel(): String? = null
+    override fun setLabel(label: String?) {}
+    override fun startTimer(ticks: Long): Int = 0
+    override fun cancelTimer(id: Int) {}
+    override fun addTrackingChange(field: TrackingField, change: Long) {}
+}
+
+class EventResult(val name: String, val args: Array<Any?>)
+
+class AsyncRunner : NullApiEnvironment() {
+    private val eventStream: Channel<Array<Any?>> = Channel(Int.MAX_VALUE)
+    private val apis: MutableList<ILuaAPI> = mutableListOf()
+
+    override fun queueEvent(event: String?, vararg args: Any?) {
+        ComputerCraft.log.debug("Queue event $event ${args.contentToString()}")
+        if (!eventStream.offer(arrayOf(event, *args))) {
+            throw IllegalStateException("Queue is full")
+        }
+    }
+
+    override fun shutdown() {
+        super.shutdown()
+        eventStream.close()
+        apis.forEach { it.shutdown() }
+    }
+
+    fun <T : ILuaAPI> addApi(api: T): T {
+        apis.add(api)
+        api.startup()
+        return api
+    }
+
+    suspend fun resultOf(toRun: MethodResult): Array<Any?> {
+        var running = toRun
+        while (running.callback != null) running = runOnce(running)
+        return running.result ?: empty
+    }
+
+    private suspend fun runOnce(obj: MethodResult): MethodResult {
+        val callback = obj.callback ?: throw NullPointerException("Callback cannot be null")
+
+        val result = obj.result
+        val filter: String? = if (result.isNullOrEmpty() || result[0] !is String) {
+            null
+        } else {
+            result[0] as String
+        }
+
+        return callback.resume(pullEventImpl(filter))
+    }
+
+    private suspend fun pullEventImpl(filter: String?): Array<Any?> {
+        for (event in eventStream) {
+            ComputerCraft.log.debug("Pulled event ${event.contentToString()}")
+            val eventName = event[0] as String
+            if (filter == null || eventName == filter || eventName == "terminate") return event
+        }
+
+        throw IllegalStateException("No more events")
+    }
+
+    suspend fun pullEvent(filter: String? = null): EventResult {
+        val result = pullEventImpl(filter)
+        return EventResult(result[0] as String, result.copyOfRange(1, result.size))
+    }
+
+    companion object {
+        private val empty: Array<Any?> = arrayOf()
+
+        @OptIn(ExperimentalTime::class)
+        fun runTest(timeout: Duration = 5.seconds, fn: suspend AsyncRunner.() -> Unit) {
+            runBlocking {
+                val runner = AsyncRunner()
+                try {
+                    withTimeout(timeout) { fn(runner) }
+                } finally {
+                    runner.shutdown()
+                }
+            }
+        }
+    }
+}

src/test/java/dan200/computercraft/core/apis/http/options/TestHttpApi.kt

@@ -0,0 +1,51 @@
+package dan200.computercraft.core.apis.http.options
+
+import dan200.computercraft.ComputerCraft
+import dan200.computercraft.core.apis.AsyncRunner
+import dan200.computercraft.core.apis.HTTPAPI
+import org.junit.jupiter.api.AfterAll
+import org.junit.jupiter.api.Assertions.assertArrayEquals
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.BeforeAll
+import org.junit.jupiter.api.Disabled
+import org.junit.jupiter.api.Test
+import java.util.*
+
+@Disabled("Requires some setup locally.")
+class TestHttpApi {
+    companion object {
+        private const val WS_ADDRESS = "ws://127.0.0.1:8080"
+
+        @JvmStatic
+        @BeforeAll
+        fun before() {
+            ComputerCraft.httpRules = listOf(AddressRule.parse("*", null, Action.ALLOW.toPartial()))
+        }
+
+        @JvmStatic
+        @AfterAll
+        fun after() {
+            ComputerCraft.httpRules = Collections.unmodifiableList(
+                listOf(
+                    AddressRule.parse("\$private", null, Action.DENY.toPartial()),
+                    AddressRule.parse("*", null, Action.ALLOW.toPartial())
+                )
+            )
+        }
+    }
+
+    @Test
+    fun `Connects to websocket`() {
+        AsyncRunner.runTest {
+            val httpApi = addApi(HTTPAPI(this))
+
+            val result = httpApi.websocket(WS_ADDRESS, Optional.empty())
+            assertArrayEquals(arrayOf(true), result, "Should have created websocket")
+
+            val event = pullEvent()
+            assertEquals("websocket_success", event.name) {
+                "Websocket failed to connect: ${event.args.contentToString()}"
+            }
+        }
+    }
+}

src/test/java/dan200/computercraft/ingame/CraftOsTest.kt

@@ -0,0 +1,13 @@
+package dan200.computercraft.ingame
+
+import dan200.computercraft.ingame.api.GameTest
+import dan200.computercraft.ingame.api.TestContext
+import dan200.computercraft.ingame.api.checkComputerOk
+
+class CraftOsTest {
+    /**
+     * Sends a rednet message to another a computer and back again.
+     */
+    @GameTest
+    suspend fun `Sends basic rednet messages`(context: TestContext) = context.checkComputerOk(13)
+}

src/test/java/dan200/computercraft/ingame/MonitorTest.kt

@@ -0,0 +1,39 @@
+package dan200.computercraft.ingame
+
+import dan200.computercraft.ingame.api.*
+import dan200.computercraft.shared.Registry
+import dan200.computercraft.shared.peripheral.monitor.TileMonitor
+import net.minecraft.block.Blocks
+import net.minecraft.command.arguments.BlockStateInput
+import net.minecraft.nbt.CompoundNBT
+import net.minecraft.util.math.BlockPos
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.fail
+import java.util.*
+
+class MonitorTest {
+    @GameTest
+    suspend fun `Ensures valid on place`(context: TestContext) {
+        val pos = BlockPos(2, 0, 2)
+        val tag = CompoundNBT()
+        tag.putInt("Width", 2)
+        tag.putInt("Height", 2)
+
+        val toSet = BlockStateInput(
+            Registry.ModBlocks.MONITOR_ADVANCED.get().defaultBlockState(),
+            Collections.emptySet(),
+            tag
+        )
+
+        context.setBlock(pos, Blocks.AIR.defaultBlockState())
+        context.setBlock(pos, toSet)
+
+        context.sleep(2)
+
+        val tile = context.getTile(pos)
+        if (tile !is TileMonitor) fail("Expected tile to be monitor, is $tile")
+
+        assertEquals(1, tile.width, "Width should be 1")
+        assertEquals(1, tile.height, "Width should be 1")
+    }
+}

src/test/java/dan200/computercraft/ingame/api/TestExtensions.kt

@@ -3,6 +3,7 @@ package dan200.computercraft.ingame.api
 import kotlinx.coroutines.CancellationException
 import kotlinx.coroutines.delay
 import net.minecraft.block.BlockState
+import net.minecraft.command.arguments.BlockStateInput
 import net.minecraft.entity.Entity
 import net.minecraft.tileentity.TileEntity
 import net.minecraft.util.math.AxisAlignedBB
@@ -54,6 +55,11 @@ fun TestContext.setBlock(pos: BlockPos, state: BlockState) {
     tracker.level.setBlockAndUpdate(offset(pos), state)
 }
 
+/**
+ * Set a block within the test structure.
+ */
+fun TestContext.setBlock(pos: BlockPos, state: BlockStateInput) = state.place(tracker.level, offset(pos), 3)
+
 /**
  * Modify a block state within the test.
  */

src/test/server-files/computers/computer/11/startup.lua

@@ -1,3 +1,5 @@
+-- TurtleTest.`Use compostors`
+
 test.eq(true, turtle.dropDown(), "Drop items into compostor")
 
 test.ok()

src/test/server-files/computers/computer/12/startup.lua

@@ -1,3 +1,5 @@
+-- TurtleTest.`Cleaned with cauldrons`
+
 local old_details = turtle.getItemDetail(1, true)
 
 test.assert(turtle.place(), "Dyed turtle")

src/test/server-files/computers/computer/13/startup.lua

@@ -0,0 +1,14 @@
+-- CraftOsTest.`Sends basic rednet messages`
+
+rednet.open("top")
+
+local id, msg
+repeat
+    rednet.send(14, "Test msg") -- Keep sending, as other computer may not have started yet.
+
+    id, msg = rednet.receive(nil, 1)
+    print(id, msg)
+until id == 14
+
+test.eq("Test msg", msg)
+test.ok()

src/test/server-files/computers/computer/14/startup.lua

@@ -0,0 +1,7 @@
+-- CraftOsTest.`Sends basic rednet messages`
+
+rednet.open("top")
+while true do
+    local id, msg, protocol = rednet.receive()
+    rednet.send(id, msg, protocol)
+end

src/test/server-files/computers/ids.json

@@ -1,3 +1,3 @@
 {
-  "computer": 12
+  "computer": 14
 }

src/test/server-files/structures/craft_os_test.sends_basic_rednet_messages.snbt

@@ -0,0 +1,555 @@
+{
+    size: [5, 5, 5],
+    entities: [],
+    blocks: [
+        {
+            pos: [0, 0, 0],
+            state: 0
+        },
+        {
+            pos: [1, 0, 0],
+            state: 0
+        },
+        {
+            pos: [2, 0, 0],
+            state: 0
+        },
+        {
+            pos: [3, 0, 0],
+            state: 0
+        },
+        {
+            pos: [4, 0, 0],
+            state: 0
+        },
+        {
+            pos: [0, 0, 1],
+            state: 0
+        },
+        {
+            pos: [1, 0, 1],
+            state: 0
+        },
+        {
+            pos: [2, 0, 1],
+            state: 0
+        },
+        {
+            pos: [3, 0, 1],
+            state: 0
+        },
+        {
+            pos: [4, 0, 1],
+            state: 0
+        },
+        {
+            pos: [0, 0, 2],
+            state: 0
+        },
+        {
+            pos: [1, 0, 2],
+            state: 0
+        },
+        {
+            pos: [2, 0, 2],
+            state: 0
+        },
+        {
+            pos: [3, 0, 2],
+            state: 0
+        },
+        {
+            pos: [4, 0, 2],
+            state: 0
+        },
+        {
+            pos: [0, 0, 3],
+            state: 0
+        },
+        {
+            pos: [1, 0, 3],
+            state: 0
+        },
+        {
+            pos: [2, 0, 3],
+            state: 0
+        },
+        {
+            pos: [3, 0, 3],
+            state: 0
+        },
+        {
+            pos: [4, 0, 3],
+            state: 0
+        },
+        {
+            pos: [0, 0, 4],
+            state: 0
+        },
+        {
+            pos: [1, 0, 4],
+            state: 0
+        },
+        {
+            pos: [2, 0, 4],
+            state: 0
+        },
+        {
+            pos: [3, 0, 4],
+            state: 0
+        },
+        {
+            pos: [4, 0, 4],
+            state: 0
+        },
+        {
+            nbt: {
+                Label: "Echo",
+                id: "computercraft:computer_advanced",
+                ComputerId: 14,
+                On: 1b
+            },
+            pos: [1, 1, 2],
+            state: 1
+        },
+        {
+            nbt: {
+                Label: "Main",
+                id: "computercraft:computer_advanced",
+                ComputerId: 13,
+                On: 1b
+            },
+            pos: [3, 1, 2],
+            state: 2
+        },
+        {
+            nbt: {
+                id: "computercraft:wireless_modem_normal"
+            },
+            pos: [1, 2, 2],
+            state: 3
+        },
+        {
+            nbt: {
+                id: "computercraft:wireless_modem_normal"
+            },
+            pos: [3, 2, 2],
+            state: 3
+        },
+        {
+            pos: [0, 1, 0],
+            state: 4
+        },
+        {
+            pos: [1, 1, 0],
+            state: 4
+        },
+        {
+            pos: [2, 1, 0],
+            state: 4
+        },
+        {
+            pos: [3, 1, 0],
+            state: 4
+        },
+        {
+            pos: [4, 1, 0],
+            state: 4
+        },
+        {
+            pos: [0, 2, 0],
+            state: 4
+        },
+        {
+            pos: [1, 2, 0],
+            state: 4
+        },
+        {
+            pos: [2, 2, 0],
+            state: 4
+        },
+        {
+            pos: [3, 2, 0],
+            state: 4
+        },
+        {
+            pos: [4, 2, 0],
+            state: 4
+        },
+        {
+            pos: [0, 3, 0],
+            state: 4
+        },
+        {
+            pos: [1, 3, 0],
+            state: 4
+        },
+        {
+            pos: [2, 3, 0],
+            state: 4
+        },
+        {
+            pos: [3, 3, 0],
+            state: 4
+        },
+        {
+            pos: [4, 3, 0],
+            state: 4
+        },
+        {
+            pos: [0, 4, 0],
+            state: 4
+        },
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+        {
+            pos: [4, 4, 4],
+            state: 4
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+    ],
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+        {
+            Name: "minecraft:polished_andesite"
+        },
+        {
+            Properties: {
+                facing: "north",
+                state: "on"
+            },
+            Name: "computercraft:computer_advanced"
+        },
+        {
+            Properties: {
+                facing: "north",
+                state: "blinking"
+            },
+            Name: "computercraft:computer_advanced"
+        },
+        {
+            Properties: {
+                waterlogged: "false",
+                facing: "down",
+                on: "true"
+            },
+            Name: "computercraft:wireless_modem_normal"
+        },
+        {
+            Name: "minecraft:air"
+        }
+    ],
+    DataVersion: 2230
+}

src/test/server-files/structures/monitor_test.ensures_valid_on_place.snbt

@@ -0,0 +1,515 @@
+{
+    size: [5, 5, 5],
+    entities: [],
+    blocks: [
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+            pos: [0, 0, 0],
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+        },
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+        {
+            pos: [4, 4, 4],
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+        }
+    ],
+    palette: [
+        {
+            Name: "minecraft:polished_andesite"
+        },
+        {
+            Name: "minecraft:air"
+        }
+    ],
+    DataVersion: 2230
+}