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Paper 1.19 compat via dynamic code gen
Java byte code is a special flavor of utterly cursed
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...in/src/main/java/com/denizenscript/denizen/utilities/packets/NetworkInterceptCodeGen.java
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,123 @@ | ||
| package com.denizenscript.denizen.utilities.packets; | ||
|
|
||
| import com.denizenscript.denizen.nms.NMSHandler; | ||
| import com.denizenscript.denizen.utilities.debugging.Debug; | ||
| import com.denizenscript.denizencore.utilities.codegen.CodeGenUtil; | ||
| import org.objectweb.asm.*; | ||
|
|
||
| import java.lang.invoke.MethodHandle; | ||
| import java.lang.invoke.MethodHandles; | ||
| import java.lang.reflect.Constructor; | ||
| import java.lang.reflect.Field; | ||
| import java.lang.reflect.Method; | ||
| import java.lang.reflect.Modifier; | ||
|
|
||
| public class NetworkInterceptCodeGen { | ||
|
|
||
| public static MethodHandle generateInstance = null; | ||
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|
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| public static void generateClass(Class<?> denClass, Class<?> abstractClass, Class<?> nmsClass) { | ||
| try { | ||
| Constructor<?> origConstructor = denClass.getConstructors()[0]; | ||
| // ====== Build class ====== | ||
| String className = "com/denizenscript/denizen/network_intercept_codegen/GeneratedInterceptor"; | ||
| ClassWriter cw = new ClassWriter(ClassWriter.COMPUTE_MAXS | ClassWriter.COMPUTE_FRAMES); | ||
| cw.visit(Opcodes.V1_8, Opcodes.ACC_PUBLIC, className, null, Type.getInternalName(denClass), new String[0]); | ||
| cw.visitSource("GENERATED_INTERCEPTOR", null); | ||
| // ====== Build constructor ====== | ||
| MethodVisitor mv = cw.visitMethod(Opcodes.ACC_PUBLIC, "<init>", Type.getConstructorDescriptor(origConstructor), null, null); | ||
| mv.visitCode(); | ||
| Label startLabel = new Label(); | ||
| mv.visitLabel(startLabel); | ||
| mv.visitLineNumber(0, startLabel); | ||
| mv.visitVarInsn(Opcodes.ALOAD, 0); | ||
| mv.visitVarInsn(Opcodes.ALOAD, 1); | ||
| mv.visitVarInsn(Opcodes.ALOAD, 2); | ||
| mv.visitMethodInsn(Opcodes.INVOKESPECIAL, Type.getInternalName(denClass), "<init>", Type.getConstructorDescriptor(origConstructor), false); | ||
| mv.visitInsn(Opcodes.RETURN); | ||
| mv.visitLocalVariable("this", "L" + className + ";", null, startLabel, startLabel, 0); | ||
| mv.visitMaxs(0, 0); | ||
| mv.visitEnd(); | ||
| // ====== Find public methods ====== | ||
| for (Method method : nmsClass.getDeclaredMethods()) { | ||
| int modifier = method.getModifiers(); | ||
| if (Modifier.isPublic(modifier) && !Modifier.isFinal(modifier) && !Modifier.isStatic(modifier)) { | ||
| boolean hasMethod = false; | ||
| try { | ||
| abstractClass.getDeclaredMethod(method.getName(), method.getParameterTypes()); | ||
| hasMethod = true; | ||
| } | ||
| catch (NoSuchMethodException ignore) {} | ||
| if (!hasMethod) { | ||
| if (NMSHandler.debugPackets) { | ||
| Debug.log("Must override " + method + " --- " + method.getName() + ", returns " + method.getReturnType() + " is " + modifier | ||
| + ", Public=" + Modifier.isPublic(modifier) + ", final=" + Modifier.isFinal(modifier)); | ||
| } | ||
| mv = cw.visitMethod(Opcodes.ACC_PUBLIC, method.getName(), Type.getMethodDescriptor(method), null, null); | ||
| mv.visitCode(); | ||
| startLabel = new Label(); | ||
| mv.visitLabel(startLabel); | ||
| mv.visitLineNumber(0, startLabel); | ||
| mv.visitVarInsn(Opcodes.ALOAD, 0); | ||
| mv.visitFieldInsn(Opcodes.GETFIELD, Type.getInternalName(abstractClass), "oldListener", Type.getDescriptor(nmsClass)); | ||
| int id = 1; | ||
| for (Class<?> type : method.getParameterTypes()) { | ||
| if (NMSHandler.debugPackets) { | ||
| Debug.log("Var " + id + " is type " + type.getName()); | ||
| } | ||
| int index = id++; | ||
| if (type == int.class || type == boolean.class || type == short.class || type == char.class) { mv.visitVarInsn(Opcodes.ILOAD, index); } // Everything sub-integer-width is secretly integers | ||
| else if (type == long.class) { mv.visitVarInsn(Opcodes.LLOAD, index); id++; } | ||
| else if (type == float.class) { mv.visitVarInsn(Opcodes.FLOAD, index); } | ||
| else if (type == double.class) { mv.visitVarInsn(Opcodes.DLOAD, index); id++; } // Doubles and longs have two vars secretly for some reason | ||
| else { mv.visitVarInsn(Opcodes.ALOAD, index); } | ||
| } | ||
| mv.visitMethodInsn(Opcodes.INVOKEVIRTUAL, Type.getInternalName(nmsClass), method.getName(), Type.getMethodDescriptor(method), false); | ||
| int returnCode = Opcodes.ARETURN; | ||
| Class<?> returnType = method.getReturnType(); | ||
| if (returnType == int.class || returnType == boolean.class || returnType == short.class || returnType == char.class) { returnCode = Opcodes.IRETURN; } | ||
| else if (returnType == long.class) { returnCode = Opcodes.LRETURN; } | ||
| else if (returnType == float.class) { returnCode = Opcodes.FRETURN; } | ||
| else if (returnType == double.class) { returnCode = Opcodes.DRETURN; } | ||
| else if (returnType == void.class) { returnCode = Opcodes.RETURN; } | ||
| mv.visitInsn(returnCode); | ||
| mv.visitLocalVariable("this", "L" + className + ";", null, startLabel, startLabel, 0); | ||
| id = 1; | ||
| for (Class<?> type : method.getParameterTypes()) { | ||
| mv.visitLocalVariable("var" + id, Type.getDescriptor(type), null, startLabel, startLabel, id); | ||
| if (type == double.class || type == long.class) { | ||
| id++; | ||
| } | ||
| id++; | ||
| } | ||
| mv.visitMaxs(0, 0); | ||
| mv.visitEnd(); | ||
| } | ||
| } | ||
| } | ||
| // ====== Compile and return ====== | ||
| cw.visitEnd(); | ||
| byte[] compiled = cw.toByteArray(); | ||
| Class<?> generatedClass = CodeGenUtil.loader.define(className.replace('/', '.'), compiled); | ||
| Constructor<?> ctor = generatedClass.getDeclaredConstructor(origConstructor.getParameterTypes()); | ||
| ctor.setAccessible(true); | ||
| generateInstance = MethodHandles.lookup().unreflectConstructor(ctor); | ||
| } | ||
| catch (Throwable ex) { | ||
| Debug.echoError(ex); | ||
| } | ||
| } | ||
|
|
||
| public static Object generateAppropriateInterceptor(Object netMan, Object player, Class<?> denClass, Class<?> abstractClass, Class<?> nmsClass) { | ||
| if (generateInstance == null) { | ||
| generateClass(denClass, abstractClass, nmsClass); | ||
| } | ||
| try { | ||
| return generateInstance.invoke(netMan, player); | ||
| } | ||
| catch (Throwable ex) { | ||
| Debug.echoError(ex); | ||
| return null; | ||
| } | ||
| } | ||
| } |
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