From 6c3d98702c9853003230e7463680562c37848f19 Mon Sep 17 00:00:00 2001
From: Graham <gpe@openrs2.dev>
Date: Sat, 12 Oct 2019 21:58:54 +0100
Subject: [PATCH] Remove reset methods

---
 .../java/dev/openrs2/deob/Deobfuscator.java   |   2 +
 .../deob/transform/ResetTransformer.java      | 128 ++++++++++++++++++
 2 files changed, 130 insertions(+)
 create mode 100644 deob/src/main/java/dev/openrs2/deob/transform/ResetTransformer.java

diff --git a/deob/src/main/java/dev/openrs2/deob/Deobfuscator.java b/deob/src/main/java/dev/openrs2/deob/Deobfuscator.java
index 0272602d38..4d31c2ed4a 100644
--- a/deob/src/main/java/dev/openrs2/deob/Deobfuscator.java
+++ b/deob/src/main/java/dev/openrs2/deob/Deobfuscator.java
@@ -23,6 +23,7 @@ import dev.openrs2.deob.transform.FieldOrderTransformer;
 import dev.openrs2.deob.transform.OpaquePredicateTransformer;
 import dev.openrs2.deob.transform.OriginalNameTransformer;
 import dev.openrs2.deob.transform.RemapTransformer;
+import dev.openrs2.deob.transform.ResetTransformer;
 import dev.openrs2.deob.transform.UnusedArgTransformer;
 import org.objectweb.asm.tree.analysis.AnalyzerException;
 import org.slf4j.Logger;
@@ -45,6 +46,7 @@ public final class Deobfuscator {
 		.add(new DummyArgTransformer())
 		.add(new DummyLocalTransformer())
 		.add(new UnusedArgTransformer())
+		.add(new ResetTransformer())
 		.add(new AccessTransformer())
 		.build();
 
diff --git a/deob/src/main/java/dev/openrs2/deob/transform/ResetTransformer.java b/deob/src/main/java/dev/openrs2/deob/transform/ResetTransformer.java
new file mode 100644
index 0000000000..0fbe0c8f1f
--- /dev/null
+++ b/deob/src/main/java/dev/openrs2/deob/transform/ResetTransformer.java
@@ -0,0 +1,128 @@
+package dev.openrs2.deob.transform;
+
+import java.util.HashSet;
+import java.util.Set;
+
+import dev.openrs2.asm.InsnNodeUtils;
+import dev.openrs2.asm.MemberRef;
+import dev.openrs2.asm.MethodNodeUtils;
+import dev.openrs2.asm.classpath.ClassPath;
+import dev.openrs2.asm.classpath.Library;
+import dev.openrs2.asm.transform.Transformer;
+import org.objectweb.asm.Opcodes;
+import org.objectweb.asm.tree.AbstractInsnNode;
+import org.objectweb.asm.tree.ClassNode;
+import org.objectweb.asm.tree.InsnNode;
+import org.objectweb.asm.tree.LdcInsnNode;
+import org.objectweb.asm.tree.MethodInsnNode;
+import org.objectweb.asm.tree.MethodNode;
+import org.objectweb.asm.tree.VarInsnNode;
+import org.objectweb.asm.tree.analysis.AnalyzerException;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public final class ResetTransformer extends Transformer {
+	private static final Logger logger = LoggerFactory.getLogger(ResetTransformer.class);
+
+	private static MemberRef findMasterReset(MethodNode method) {
+		AbstractInsnNode shutdownLdc = null;
+
+		for (var insn : method.instructions) {
+			if (insn.getOpcode() != Opcodes.LDC) {
+				continue;
+			}
+
+			var ldc = (LdcInsnNode) insn;
+			if (ldc.cst.equals("Shutdown complete - clean:")) {
+				shutdownLdc = ldc;
+				break;
+			}
+		}
+
+		for (var insn = shutdownLdc; insn != null; insn = insn.getPrevious()) {
+			if (insn.getOpcode() != Opcodes.ALOAD) {
+				continue;
+			}
+
+			var load = (VarInsnNode) insn;
+			if (load.var != 0) {
+				continue;
+			}
+
+			var nextInsn = InsnNodeUtils.nextReal(insn);
+			if (nextInsn.getOpcode() != Opcodes.INVOKEVIRTUAL) {
+				continue;
+			}
+
+			var invoke = (MethodInsnNode) nextInsn;
+			if (!invoke.desc.equals("()V")) {
+				continue;
+			}
+
+			return new MemberRef(invoke.owner, invoke.name, invoke.desc);
+		}
+
+		return null;
+	}
+
+	private static void findResetMethods(Set<MemberRef> resetMethods, ClassNode clazz, MethodNode method) throws AnalyzerException {
+		MethodNodeUtils.removeDeadCode(clazz.name, method);
+
+		for (var insn : method.instructions) {
+			if (insn.getOpcode() == -1 || insn.getOpcode() != Opcodes.INVOKESTATIC) {
+				continue;
+			}
+
+			var invoke = (MethodInsnNode) insn;
+			resetMethods.add(new MemberRef(invoke.owner, invoke.name, invoke.desc));
+		}
+	}
+
+	private final Set<MemberRef> resetMethods = new HashSet<>();
+
+	@Override
+	protected void preTransform(ClassPath classPath) throws AnalyzerException {
+		resetMethods.clear();
+
+		for (var library : classPath.getLibraries()) {
+			for (var clazz : library) {
+				for (var method : clazz.methods) {
+					if ((method.access & (Opcodes.ACC_NATIVE | Opcodes.ACC_ABSTRACT)) != 0) {
+						continue;
+					}
+
+					var masterReset = findMasterReset(method);
+					if (masterReset == null) {
+						continue;
+					}
+
+					logger.info("Identified master reset method: {}", masterReset);
+
+					var resetClass = classPath.getNode("client");
+					var resetMethod = resetClass.methods.stream()
+						.filter(m -> m.name.equals(masterReset.getName()) && m.desc.equals(masterReset.getDesc()))
+						.findAny()
+						.orElseThrow();
+
+					findResetMethods(resetMethods, resetClass, resetMethod);
+
+					resetMethod.instructions.clear();
+					resetMethod.tryCatchBlocks.clear();
+
+					resetMethod.instructions.add(new InsnNode(Opcodes.RETURN));
+				}
+			}
+		}
+	}
+
+	@Override
+	protected boolean transformClass(ClassPath classPath, Library library, ClassNode clazz) {
+		clazz.methods.removeIf(m -> resetMethods.contains(new MemberRef(clazz.name, m.name, m.desc)));
+		return false;
+	}
+
+	@Override
+	protected void postTransform(ClassPath classPath) {
+		logger.info("Removed {} reset methods", resetMethods.size());
+	}
+}