From 5d63904075724db4dc17f1685443fd77230a4677 Mon Sep 17 00:00:00 2001
From: Graham <gpe@openrs2.dev>
Date: Sat, 19 Oct 2019 11:43:12 +0100
Subject: [PATCH] Increase the size of the client's main packet buffer

---
 .../java/dev/openrs2/bundler/Bundler.java     |  2 +
 .../transform/BufferSizeTransformer.java      | 93 +++++++++++++++++++
 2 files changed, 95 insertions(+)
 create mode 100644 bundler/src/main/java/dev/openrs2/bundler/transform/BufferSizeTransformer.java

diff --git a/bundler/src/main/java/dev/openrs2/bundler/Bundler.java b/bundler/src/main/java/dev/openrs2/bundler/Bundler.java
index 6464a05e..94e61d8f 100644
--- a/bundler/src/main/java/dev/openrs2/bundler/Bundler.java
+++ b/bundler/src/main/java/dev/openrs2/bundler/Bundler.java
@@ -2,6 +2,7 @@ package dev.openrs2.bundler;
 
 import com.google.common.collect.ImmutableList;
 import dev.openrs2.asm.transform.Transformer;
+import dev.openrs2.bundler.transform.BufferSizeTransformer;
 import dev.openrs2.bundler.transform.CachePathTransformer;
 import dev.openrs2.bundler.transform.HostCheckTransformer;
 import dev.openrs2.bundler.transform.LoadLibraryTransformer;
@@ -10,6 +11,7 @@ import dev.openrs2.bundler.transform.RightClickTransformer;
 
 public final class Bundler {
 	public static final ImmutableList<Transformer> TRANSFORMERS = ImmutableList.of(
+		new BufferSizeTransformer(),
 		new CachePathTransformer(),
 		new HostCheckTransformer(),
 		new MacResizeTransformer(),
diff --git a/bundler/src/main/java/dev/openrs2/bundler/transform/BufferSizeTransformer.java b/bundler/src/main/java/dev/openrs2/bundler/transform/BufferSizeTransformer.java
new file mode 100644
index 00000000..65b41500
--- /dev/null
+++ b/bundler/src/main/java/dev/openrs2/bundler/transform/BufferSizeTransformer.java
@@ -0,0 +1,93 @@
+package dev.openrs2.bundler.transform;
+
+import java.util.Optional;
+
+import dev.openrs2.asm.InsnMatcher;
+import dev.openrs2.asm.InsnNodeUtils;
+import dev.openrs2.asm.MemberRef;
+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.ClassNode;
+import org.objectweb.asm.tree.FieldInsnNode;
+import org.objectweb.asm.tree.LdcInsnNode;
+import org.objectweb.asm.tree.MethodNode;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public final class BufferSizeTransformer extends Transformer {
+	private static final Logger logger = LoggerFactory.getLogger(BufferSizeTransformer.class);
+
+	private static final InsnMatcher GPP1_POS_MATCHER = InsnMatcher.compile("LDC (INVOKESPECIAL | INVOKEVIRTUAL) GETSTATIC");
+	private static final InsnMatcher NEW_BUFFER_MATCHER = InsnMatcher.compile("NEW DUP (SIPUSH | LDC) INVOKESPECIAL PUTSTATIC");
+
+	private static Optional<MemberRef> findBuffer(MethodNode method) {
+		return GPP1_POS_MATCHER.match(method)
+			.filter(match -> {
+				var ldc = (LdcInsnNode) match.get(0);
+				return ldc.cst.equals("gpp1 pos:");
+			})
+			.map(match -> {
+				var getstatic = (FieldInsnNode) match.get(2);
+				return new MemberRef(getstatic.owner, getstatic.name, getstatic.desc);
+			})
+			.findAny();
+	}
+
+	private MemberRef buffer;
+	private int buffersResized;
+
+	@Override
+	protected void preTransform(ClassPath classPath) {
+		buffer = null;
+		buffersResized = 0;
+
+		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 buffer = findBuffer(method);
+					if (buffer.isEmpty()) {
+						continue;
+					}
+
+					this.buffer = buffer.orElseThrow();
+					logger.info("Identified buffer: {}", this.buffer);
+					break;
+				}
+			}
+		}
+	}
+
+	@Override
+	protected boolean transformCode(ClassPath classPath, Library library, ClassNode clazz, MethodNode method) {
+		if (buffer == null) {
+			return false;
+		}
+
+		NEW_BUFFER_MATCHER.match(method).forEach(match -> {
+			var putstatic = (FieldInsnNode) match.get(4);
+			if (!putstatic.owner.equals(buffer.getOwner())) {
+				return;
+			} else if (!putstatic.name.equals(buffer.getName())) {
+				return;
+			} else if (!putstatic.desc.equals(buffer.getDesc())) {
+				return;
+			}
+
+			method.instructions.set(match.get(2), InsnNodeUtils.createIntConstant(65535));
+			buffersResized++;
+		});
+
+		return false;
+	}
+
+	@Override
+	protected void postTransform(ClassPath classPath) {
+		logger.info("Resized {} buffers to 65535 bytes", buffersResized);
+	}
+}