Add JInput check for mouse devices with too many buttons

build.gradle

@@ -144,6 +144,9 @@ dependencies {
         testImplementation 'org.junit.jupiter:junit-jupiter:5.7.1'
         testRuntimeOnly 'org.junit.platform:junit-platform-launcher'
     }
+
+    implementation 'org.ow2.asm:asm:5.2'
+    implementation 'org.ow2.asm:asm-commons:5.2'
 }
 
 apply from: 'gradle/scripts/dependencies.gradle'

gradle.properties

@@ -115,9 +115,9 @@ mixin_refmap = mixins.${mod_id}.refmap.json
 # Only make a coremod if you are absolutely sure of what you are doing
 # Change the property `coremod_includes_mod` to false if your coremod doesn't have a @Mod annotation
 # You MUST state a class name for `coremod_plugin_class_name` if you are making a coremod, the class should implement `IFMLLoadingPlugin`
-is_coremod = false
+is_coremod = true
 coremod_includes_mod = true
-coremod_plugin_class_name =
+coremod_plugin_class_name = world.maryt.rawinput.RawInputCorePlugin
 
 # AssetMover
 # Convenient way to allow downloading of assets from official vanilla Minecraft servers, CurseForge, or any direct links

src/main/java/world/maryt/rawinput/RawInputCorePlugin.java

@@ -0,0 +1,38 @@
+package world.maryt.rawinput;
+
+import java.util.Map;
+
+import net.minecraftforge.fml.relauncher.IFMLLoadingPlugin;
+
+/**
+ * Coremod plugin that transforms jinput classes with ASM
+ * This ensures our safety check is applied before problematic input devices can crash the game
+ */
+@IFMLLoadingPlugin.MCVersion("1.12.2")
+@IFMLLoadingPlugin.Name("RawInput Coremod")
+public class RawInputCorePlugin implements IFMLLoadingPlugin {
+  @Override
+  public String[] getASMTransformerClass() {
+      return new String[]{"world.maryt.rawinput.RawInputCoreTransformer"};
+  }
+
+  @Override
+  public String getModContainerClass() {
+      return null;
+  }
+
+  @Override
+  public String getSetupClass() {
+      return null;
+  }
+
+  @Override
+  public void injectData(Map<String, Object> data) {
+      // No additional data needed
+  }
+
+  @Override
+  public String getAccessTransformerClass() {
+      return null;
+  }
+}

src/main/java/world/maryt/rawinput/RawInputCoreTransformer.java

@@ -0,0 +1,104 @@
+package world.maryt.rawinput;
+
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+import org.objectweb.asm.ClassReader;
+import org.objectweb.asm.ClassWriter;
+import org.objectweb.asm.Opcodes;
+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.JumpInsnNode;
+import org.objectweb.asm.tree.LabelNode;
+import org.objectweb.asm.tree.LdcInsnNode;
+import org.objectweb.asm.tree.MethodNode;
+import org.objectweb.asm.tree.VarInsnNode;
+
+/**
+ * ASM transformer that prevents crashes from problematic input devices
+ * by rejecting devices with num_buttons >= 32 before they can cause issues
+ */
+public class RawInputCoreTransformer implements net.minecraft.launchwrapper.IClassTransformer {
+
+    private static final Logger LOGGER = LogManager.getLogger("RawInputCoreTransformer");
+
+    @Override
+    public byte[] transform(String name, String transformedName, byte[] basicClass) {
+        // Only transform jinput classes
+        if (!name.startsWith("net.java.games.input")) {
+            return basicClass;
+        }
+
+        // Target RawMouseInfo for the safety check
+        if (name.equals("net.java.games.input.RawMouseInfo")) {
+            LOGGER.info("Applying safety check to RawMouseInfo for problematic input devices");
+            return transformRawMouseInfo(basicClass);
+        }
+
+        return basicClass;
+    }
+
+    private byte[] transformRawMouseInfo(byte[] basicClass) {
+        try {
+            ClassReader reader = new ClassReader(basicClass);
+            ClassNode classNode = new ClassNode();
+            reader.accept(classNode, 0);
+
+            // Find the createControllerFromDevice method
+            for (Object methodObj : classNode.methods) {
+                MethodNode method = (MethodNode) methodObj;
+                if (method.name.equals("createControllerFromDevice") && 
+                    method.desc.equals("(Lnet/java/games/input/RawDevice;Lnet/java/games/input/SetupAPIDevice;)Lnet/java/games/input/Controller;")) {
+
+                    LOGGER.info("Injecting safety check: rejecting devices with num_buttons >= 32");
+
+                    // Create the safety check: if (num_buttons >= 32) return null;
+                    InsnList safetyCheck = new InsnList();
+
+                    // Create a label for the jump target
+                    LabelNode skipReturnLabel = new LabelNode();
+
+                    // Load "this" (aload_0)
+                    safetyCheck.add(new VarInsnNode(Opcodes.ALOAD, 0));
+
+                    // Get the num_buttons field value
+                    safetyCheck.add(new FieldInsnNode(
+                        Opcodes.GETFIELD,
+                        "net/java/games/input/RawMouseInfo",
+                        "num_buttons",
+                        "I"
+                    ));
+
+                    // Load the constant 32
+                    safetyCheck.add(new LdcInsnNode(32));
+
+                    // Compare num_buttons >= 32 (if_icmplt means if num_buttons < 32, skip the return)
+                    safetyCheck.add(new JumpInsnNode(Opcodes.IF_ICMPLT, skipReturnLabel));
+
+                    // If num_buttons >= 32, return null
+                    safetyCheck.add(new InsnNode(Opcodes.ACONST_NULL));
+                    safetyCheck.add(new InsnNode(Opcodes.ARETURN));
+
+                    // Add the label where execution should continue if num_buttons < 32
+                    safetyCheck.add(skipReturnLabel);
+
+                    // Insert the safety check at the start of the method
+                    method.instructions.insertBefore(method.instructions.getFirst(), safetyCheck);
+
+                    LOGGER.info("Safety check successfully injected");
+                    break;
+                }
+            }
+
+            // Write the transformed class
+            ClassWriter writer = new ClassWriter(ClassWriter.COMPUTE_MAXS | ClassWriter.COMPUTE_FRAMES);
+            classNode.accept(writer);
+            return writer.toByteArray();
+
+        } catch (Exception e) {
+            LOGGER.error("Failed to transform RawMouseInfo class", e);
+            return basicClass;
+        }
+    }
+}