From 2ac95074a6ce21133ec5854c2e8cff84cb974f91 Mon Sep 17 00:00:00 2001
From: Haowei Wen <yushijinhun@gmail.com>
Date: Wed, 29 Apr 2020 01:35:27 +0800
Subject: [PATCH] Add classloader exclusion to launchwrapper (#68)

---
 .../authlibinjector/AuthlibInjector.java      |  2 +
 .../LaunchwrapperExclusionTransformer.java    | 70 +++++++++++++++++++
 2 files changed, 72 insertions(+)
 create mode 100644 src/main/java/moe/yushi/authlibinjector/transform/support/LaunchwrapperExclusionTransformer.java

diff --git a/src/main/java/moe/yushi/authlibinjector/AuthlibInjector.java b/src/main/java/moe/yushi/authlibinjector/AuthlibInjector.java
index 7346086..5812fd4 100644
--- a/src/main/java/moe/yushi/authlibinjector/AuthlibInjector.java
+++ b/src/main/java/moe/yushi/authlibinjector/AuthlibInjector.java
@@ -60,6 +60,7 @@ import moe.yushi.authlibinjector.transform.ConstantURLTransformUnit;
 import moe.yushi.authlibinjector.transform.DumpClassListener;
 import moe.yushi.authlibinjector.transform.support.AuthlibLogInterceptor;
 import moe.yushi.authlibinjector.transform.support.CitizensTransformer;
+import moe.yushi.authlibinjector.transform.support.LaunchwrapperExclusionTransformer;
 import moe.yushi.authlibinjector.transform.support.MC52974Workaround;
 import moe.yushi.authlibinjector.transform.support.MC52974_1710Workaround;
 import moe.yushi.authlibinjector.transform.support.MainArgumentsTransformer;
@@ -449,6 +450,7 @@ public final class AuthlibInjector {
 			transformer.units.add(new AuthlibLogInterceptor());
 		}
 
+		transformer.units.add(new LaunchwrapperExclusionTransformer());
 		transformer.units.add(new MainArgumentsTransformer());
 		transformer.units.add(new ConstantURLTransformUnit(urlProcessor));
 		transformer.units.add(new CitizensTransformer());
diff --git a/src/main/java/moe/yushi/authlibinjector/transform/support/LaunchwrapperExclusionTransformer.java b/src/main/java/moe/yushi/authlibinjector/transform/support/LaunchwrapperExclusionTransformer.java
new file mode 100644
index 0000000..6d5b08c
--- /dev/null
+++ b/src/main/java/moe/yushi/authlibinjector/transform/support/LaunchwrapperExclusionTransformer.java
@@ -0,0 +1,70 @@
+/*
+ * Copyright (C) 2020  Haowei Wen <yushijinhun@gmail.com> and contributors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+package moe.yushi.authlibinjector.transform.support;
+
+import static org.objectweb.asm.Opcodes.ALOAD;
+import static org.objectweb.asm.Opcodes.ASM7;
+import static org.objectweb.asm.Opcodes.INVOKEVIRTUAL;
+import java.util.Optional;
+import org.objectweb.asm.ClassVisitor;
+import org.objectweb.asm.MethodVisitor;
+import moe.yushi.authlibinjector.transform.TransformUnit;
+
+public class LaunchwrapperExclusionTransformer implements TransformUnit {
+
+	@Override
+	public Optional<ClassVisitor> transform(ClassLoader classLoader, String className, ClassVisitor writer, TransformContext context) {
+		if ("net.minecraft.launchwrapper.LaunchClassLoader".equals(className)) {
+			return Optional.of(new ClassVisitor(ASM7, writer) {
+				@Override
+				public MethodVisitor visitMethod(int access, String name, String descriptor, String signature, String[] exceptions) {
+					if ("<init>".equals(name)) {
+						return new MethodVisitor(ASM7, super.visitMethod(access, name, descriptor, signature, exceptions)) {
+
+							boolean exclusionAdded = false;
+
+							@Override
+							public void visitMethodInsn(int opcode, String owner, String name, String descriptor, boolean isInterface) {
+								super.visitMethodInsn(opcode, owner, name, descriptor, isInterface);
+
+								if (!exclusionAdded &&
+										opcode == INVOKEVIRTUAL &&
+										"net/minecraft/launchwrapper/LaunchClassLoader".equals(owner) &&
+										"addClassLoaderExclusion".equals(name) &&
+										"(Ljava/lang/String;)V".equals(descriptor)) {
+									super.visitVarInsn(ALOAD, 0);
+									super.visitLdcInsn("moe.yushi.authlibinjector.");
+									super.visitMethodInsn(opcode, owner, name, descriptor, isInterface);
+									exclusionAdded = true;
+									context.markModified();
+								}
+							}
+						};
+					}
+					return super.visitMethod(access, name, descriptor, signature, exceptions);
+				}
+			});
+		} else {
+			return Optional.empty();
+		}
+	}
+
+	@Override
+	public String toString() {
+		return "Launchwrapper ClassLoader Exclusion";
+	}
+}