Implementation

Author: TheAndrey

build.gradle

@@ -16,6 +16,10 @@ idea {
 	}
 }
 
+ext {
+	loadingPlugin = 'me.theandrey.mods.sidefix.LoadingPlugin'
+}
+
 minecraft {
 	mappings channel: 'stable', version: '39-1.12'
 
@@ -25,6 +29,7 @@ minecraft {
 			workingDirectory project.file('run')
 			property 'forge.logging.markers', 'SCAN,REGISTRIES,REGISTRYDUMP' // Recommended logging data for a userdev environment
 			property 'forge.logging.console.level', 'debug' // Recommended logging level for the console
+			property 'fml.coreMods.load', project.loadingPlugin
 		}
 
 		client {
@@ -46,7 +51,7 @@ tasks.withType(JavaCompile).configureEach {
 
 jar {
 	manifest {
-		attributes 'FMLCorePlugin': 'LoadingPlugin'
+		attributes 'FMLCorePlugin': project.loadingPlugin
 		attributes 'FMLCorePluginContainsFMLMod': 'false'
 	}
 }

src/main/java/me/theandrey/mods/sidefix/ASMHelper.java

@@ -0,0 +1,23 @@
+package me.theandrey.mods.sidefix;
+
+import org.objectweb.asm.ClassReader;
+import org.objectweb.asm.ClassWriter;
+import org.objectweb.asm.tree.ClassNode;
+
+public final class ASMHelper {
+
+	private ASMHelper() {
+	}
+
+	public static ClassNode readClass(byte[] bytes) {
+		ClassNode node = new ClassNode();
+		new ClassReader(bytes).accept(node, 0);
+		return node;
+	}
+
+	public static byte[] writeClass(ClassNode node, int flags) {
+		ClassWriter writer = new ClassWriter(flags);
+		node.accept(writer);
+		return writer.toByteArray();
+	}
+}

src/main/java/me/theandrey/mods/sidefix/ClassTransformer.java

@@ -0,0 +1,53 @@
+package me.theandrey.mods.sidefix;
+
+import java.util.ListIterator;
+import net.minecraft.launchwrapper.IClassTransformer;
+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.MethodInsnNode;
+import org.objectweb.asm.tree.MethodNode;
+
+public class ClassTransformer implements IClassTransformer {
+
+	@Override
+	public byte[] transform(String name, String transformedName, byte[] bytes) {
+		if (bytes != null && name.equals("net.minecraftforge.fml.common.network.NetworkRegistry")) {
+			return redirectSideValues(bytes);
+		}
+
+		return bytes;
+	}
+
+	private byte[] redirectSideValues(byte[] bytes) {
+		ClassNode clazz = ASMHelper.readClass(bytes);
+		boolean patched = false;
+
+		for (MethodNode method : clazz.methods) {
+			ListIterator<AbstractInsnNode> iterator = method.instructions.iterator();
+
+			while (iterator.hasNext()) {
+				AbstractInsnNode node = iterator.next();
+
+				if (node.getOpcode() == Opcodes.INVOKESTATIC) {
+					MethodInsnNode methodNode = (MethodInsnNode)node;
+
+					if (methodNode.owner.equals("net/minecraftforge/fml/relauncher/Side") && methodNode.name.equals("values")) {
+						FieldInsnNode fieldNode = new FieldInsnNode(Opcodes.GETSTATIC, "me/theandrey/mods/sidefix/LoadingPlugin", "VALID_SIDES", "[Lnet/minecraftforge/fml/relauncher/Side;");
+						iterator.set(fieldNode);
+						patched = true;
+
+						LoadingPlugin.LOGGER.debug("Replaced Side.values() call in {}#{}", clazz.name, method.name);
+					}
+				}
+			}
+		}
+
+		if (patched) {
+			return ASMHelper.writeClass(clazz, 0);
+		}
+
+		return bytes;
+	}
+}

src/main/java/me/theandrey/mods/sidefix/LoadingPlugin.java

@@ -0,0 +1,39 @@
+package me.theandrey.mods.sidefix;
+
+import java.util.Map;
+import net.minecraftforge.fml.relauncher.IFMLLoadingPlugin;
+import net.minecraftforge.fml.relauncher.Side;
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+
+@IFMLLoadingPlugin.MCVersion("1.12.2")
+@IFMLLoadingPlugin.SortingIndex(900) // Obf
+public class LoadingPlugin implements IFMLLoadingPlugin {
+
+	static final Logger LOGGER = LogManager.getLogger(LoadingPlugin.class);
+	public static final Side[] VALID_SIDES = {Side.CLIENT, Side.SERVER};
+
+	@Override
+	public String[] getASMTransformerClass() {
+		return new String[]{"me.theandrey.mods.sidefix.ClassTransformer"};
+	}
+
+	@Override
+	public String getModContainerClass() {
+		return null;
+	}
+
+	@Override
+	public String getSetupClass() {
+		return null;
+	}
+
+	@Override
+	public void injectData(Map<String, Object> map) {
+	}
+
+	@Override
+	public String getAccessTransformerClass() {
+		return null;
+	}
+}