Fix in-game changes not saving to config

src/main/java/io/github/cadiboo/nocubes/hooks/Hooks.java

@@ -4,6 +4,7 @@
 import io.github.cadiboo.nocubes.client.render.RenderDispatcher;
 import io.github.cadiboo.nocubes.collision.CollisionHandler;
 import io.github.cadiboo.nocubes.config.NoCubesConfig;
+import io.github.cadiboo.nocubes.network.NoCubesNetwork;
 import net.minecraft.block.state.IBlockState;
 import net.minecraft.client.multiplayer.WorldClient;
 import net.minecraft.client.renderer.BlockRendererDispatcher;
@@ -20,6 +21,7 @@
 import net.minecraft.world.IBlockAccess;
 import net.minecraft.world.World;
 import net.minecraft.world.border.WorldBorder;
+import net.minecraftforge.fml.common.network.handshake.FMLHandshakeMessage;
 import net.minecraftforge.fml.relauncher.Side;
 import net.minecraftforge.fml.relauncher.SideOnly;
 
@@ -51,7 +53,7 @@ public static void preIteration(final RenderChunk renderChunk, final float x, fi
 	@SideOnly(Side.CLIENT)
 	public static boolean renderBlockDamage(final Tessellator tessellatorIn, final BufferBuilder bufferBuilderIn, final BlockPos blockpos, final IBlockState iblockstate, final WorldClient world, final TextureAtlasSprite textureatlassprite, final BlockRendererDispatcher blockrendererdispatcher) {
 		if (!NoCubesConfig.Client.render || !NoCubes.smoothableHandler.isSmoothable(iblockstate)) {
-				return true;
+			return true;
 		}
 		RenderDispatcher.renderBreakingTexture(tessellatorIn, bufferBuilderIn, blockpos, iblockstate, world, textureatlassprite);
 		return false;
@@ -79,4 +81,18 @@ public static boolean canBlockStateRender(final IBlockState blockstate) {
 		return !NoCubesConfig.Client.render || !NoCubes.smoothableHandler.isSmoothable(blockstate);
 	}
 
+	/**
+	 * Called from: {@link net.minecraftforge.fml.common.network.internal.FMLNetworkHandler#checkModList(FMLHandshakeMessage.ModList, Side)} when it is invoked during client/server connection handshake.
+	 * Calls: Nothing
+	 * Lets us find out if the server we are connecting to has NoCubes installed.
+	 * NB: This is not called when looking at the list of servers in the 'Multiplayer' menu, only when actually connecting to a server.
+	 * NB: This is also called for singleplayer.
+	 */
+	public static void onCheckModList(FMLHandshakeMessage.ModList modListPacket, Side side) {
+		// We only care about the server's mod list, not the client's
+		if (side == Side.SERVER) {
+			NoCubesNetwork.currentServerHasNoCubes = modListPacket.modList().containsKey(NoCubes.MOD_ID);
+		}
+	}
+
 }

src/main/java/io/github/cadiboo/nocubes/tempcore/FMLNetworkHandlerTransformer.java

@@ -0,0 +1,104 @@
+package io.github.cadiboo.nocubes.tempcore;
+
+import org.objectweb.asm.Opcodes;
+import org.objectweb.asm.tree.AbstractInsnNode;
+import org.objectweb.asm.tree.ClassNode;
+import org.objectweb.asm.tree.FieldInsnNode;
+import org.objectweb.asm.tree.InsnList;
+import org.objectweb.asm.tree.InsnNode;
+import org.objectweb.asm.tree.LabelNode;
+import org.objectweb.asm.tree.MethodInsnNode;
+import org.objectweb.asm.tree.MethodNode;
+import org.objectweb.asm.tree.VarInsnNode;
+
+import java.util.List;
+
+import static io.github.cadiboo.nocubes.tempcore.NoCubesClassTransformer.finish;
+import static io.github.cadiboo.nocubes.tempcore.NoCubesClassTransformer.log;
+import static io.github.cadiboo.nocubes.tempcore.NoCubesClassTransformer.mapField;
+import static io.github.cadiboo.nocubes.tempcore.NoCubesClassTransformer.start;
+
+/**
+ * @author Cadiboo
+ */
+final class FMLNetworkHandlerTransformer implements Opcodes {
+
+	// Local variable indexes
+	private static final int ALOCALVARIABLE_this = 0;
+	private static final int ALOCALVARIABLE_movingEntity = 1;
+	private static final int ALOCALVARIABLE_area = 2;
+	private static final int ALOCALVARIABLE_entityShape = 3;
+	private static final int ILOCALVARIABLE_flag1 = 6;
+
+	static void transform(final ClassNode classNode) {
+
+		final List<MethodNode> methods = classNode.methods;
+
+		//getCollisionBoxes
+		{
+			final String targetMethodDesc = "(Lnet/minecraftforge/fml/common/network/handshake/FMLHandshakeMessage$ModList;Lnet/minecraftforge/fml/relauncher/Side;)Ljava/lang/String;";
+			final String targetMethodName = "checkModList";
+
+			start("Find " + targetMethodName);
+			for (final MethodNode method : methods) {
+
+				if (!method.name.equals(targetMethodName)) {
+					log("Did not match method name " + targetMethodName + " - " + method.name);
+					continue;
+				} else if (!method.desc.equals(targetMethodDesc)) {
+					log("Did not match method desc " + targetMethodDesc + " - " + method.desc);
+					continue;
+				}
+				log("Matched method " + method.name + " " + method.desc);
+
+				finish();
+
+				start("Inject checkModList hook");
+				injectCheckModList(method.instructions);
+				finish();
+				break;
+
+			}
+		}
+	}
+
+	private static void injectCheckModList(InsnList instructions) {
+		AbstractInsnNode firstLabel = null;
+		int arrayLength = instructions.size();
+		for (int i = 0; i < arrayLength; ++i) {
+			AbstractInsnNode instruction = instructions.get(i);
+			if (instruction.getType() == AbstractInsnNode.LABEL) {
+				firstLabel = instruction;
+				log("Found injection point " + instruction);
+				break;
+			}
+		}
+		if (firstLabel == null) {
+			throw new RuntimeException("Error: Couldn't find injection point!");
+		}
+
+		InsnList toInject = new InsnList();
+
+		// Make list of instructions to inject
+		toInject.add(new VarInsnNode(ALOAD, 0));
+		toInject.add(new VarInsnNode(ALOAD, 1));
+		toInject.add(new MethodInsnNode(
+				//int opcode
+				INVOKESTATIC,
+				//String owner
+				"io/github/cadiboo/nocubes/hooks/Hooks",
+				//String name
+				"onCheckModList",
+				//String descriptor
+				"(Lnet/minecraftforge/fml/common/network/handshake/FMLHandshakeMessage$ModList;Lnet/minecraftforge/fml/relauncher/Side;)V",
+				//boolean isInterface
+				false
+		));
+		toInject.add(new LabelNode());
+
+		// Inject instructions
+		instructions.insert(firstLabel, toInject);
+
+	}
+
+}

src/main/java/io/github/cadiboo/nocubes/tempcore/NoCubesClassTransformer.java

@@ -96,6 +96,10 @@ public byte[] transform(final String name, final String transformedName, @Nullab
 				return transformClass(basicClass, transformedName,
 						RenderGlobalTransformer::transform
 				);
+			case "net.minecraftforge.fml.common.network.internal.FMLNetworkHandler":
+				return transformClass(basicClass, transformedName,
+					FMLNetworkHandlerTransformer::transform
+				);
 		}
 		return basicClass;
 	}