From 2c1c8cb3306f719d17adcca216b3f4c0b09745d9 Mon Sep 17 00:00:00 2001
From: Dogboy21 <info@dogboy.io>
Date: Sat, 19 Aug 2023 13:11:34 +0200
Subject: [PATCH] fix(fabric-agent): allow SiB classes to be loaded from the
 parent classloader

---
 .../agent/SIBTransformer.java                 |  1 +
 .../agent/SerializationIsBadAgent.java        | 38 +++++++++++++++++++
 2 files changed, 39 insertions(+)

diff --git a/agent/src/main/java/io/dogboy/serializationisbad/agent/SIBTransformer.java b/agent/src/main/java/io/dogboy/serializationisbad/agent/SIBTransformer.java
index a38dd21..16fbeb2 100644
--- a/agent/src/main/java/io/dogboy/serializationisbad/agent/SIBTransformer.java
+++ b/agent/src/main/java/io/dogboy/serializationisbad/agent/SIBTransformer.java
@@ -12,6 +12,7 @@ public byte[] transform(ClassLoader loader, String className, Class<?> classBein
         try {
             if (className == null) return classfileBuffer;
             if ("net/minecraft/launchwrapper/ITweaker".equals(className)) SerializationIsBadAgent.insertLaunchWrapperExclusion();
+            if ("net/fabricmc/loader/ModContainer".equals(className)) SerializationIsBadAgent.insertFabricValidParentUrl(loader);
 
             String classNameDots = className.replace('/', '.');
 
diff --git a/agent/src/main/java/io/dogboy/serializationisbad/agent/SerializationIsBadAgent.java b/agent/src/main/java/io/dogboy/serializationisbad/agent/SerializationIsBadAgent.java
index 9198f8b..1e8c793 100644
--- a/agent/src/main/java/io/dogboy/serializationisbad/agent/SerializationIsBadAgent.java
+++ b/agent/src/main/java/io/dogboy/serializationisbad/agent/SerializationIsBadAgent.java
@@ -6,6 +6,9 @@
 import java.lang.instrument.Instrumentation;
 import java.lang.reflect.Field;
 import java.lang.reflect.Method;
+import java.nio.file.Path;
+import java.util.HashSet;
+import java.util.Set;
 
 public class SerializationIsBadAgent {
 
@@ -35,4 +38,39 @@ static void insertLaunchWrapperExclusion() {
         }
     }
 
+    /**
+     * Another hacky workaround for newer Fabric versions that enforce
+     * classpath isolation. This adds the path to the SiB jar to the
+     * list of jar paths that are allowed to be loaded by the parent
+     * classloader
+     *
+     * @param fabricClassLoader The classloader that was used to load the Fabric classes
+     */
+    static void insertFabricValidParentUrl(ClassLoader fabricClassLoader) {
+        try {
+            Path sibPath = new File(SerializationIsBadAgent.class.getProtectionDomain().getCodeSource().getLocation().toURI()).toPath();
+
+            // basically accessing the following:
+            // ((KnotClassDelegate) ((Knot) FabricLauncherBase.getLauncher()).classLoader).validParentCodeSources
+
+            Class<?> fabricLauncherBaseClass = Class.forName("net.fabricmc.loader.impl.launch.FabricLauncherBase", true, fabricClassLoader);
+            Method getLauncherMethod = fabricLauncherBaseClass.getDeclaredMethod("getLauncher");
+            Object fabricLauncher = getLauncherMethod.invoke(null);
+            Field classLoaderField = fabricLauncher.getClass().getDeclaredField("classLoader");
+            classLoaderField.setAccessible(true);
+            Object classLoader = classLoaderField.get(fabricLauncher);
+            Field validParentCodeSourcesField = classLoader.getClass().getDeclaredField("validParentCodeSources");
+            validParentCodeSourcesField.setAccessible(true);
+            @SuppressWarnings("unchecked")
+            Set<Path> validParentCodeSources = (Set<Path>) validParentCodeSourcesField.get(classLoader);
+
+            Set<Path> newValidParentCodeSources = new HashSet<>(validParentCodeSources);
+            newValidParentCodeSources.add(sibPath);
+
+            validParentCodeSourcesField.set(classLoader, newValidParentCodeSources);
+        } catch (Throwable e) {
+            SerializationIsBad.logger.error("Failed to insert Fabric valid parent URL", e);
+        }
+    }
+
 }