从拦截器 bytebuddy 调用超类方法

Question

我们有一个混淆的 class，我们需要使用 bytebuddy 来增强它。我们基本上需要重新定义一个方法。 Subclassing 似乎不起作用（代码未执行）。变基有效，但在我们拦截的方法中，我们需要调用 superclass （现在说 superclass 就像 "inheritance" ）方法。

class Parent {
  public void connect(){
  ...
  };
}

class WeNeedToHackThis extends Parent {
     public void connect(InetAddress addr){
       //... this is what we want to hack
     }
     public void connect(){
       this.connect(null);
       // this is getting called from interceptor :( which delegates to our hacked method
       // we need to call "real" superclass's (Parent) method instead
     }

}
...
Class<?> dynamic = new ByteBuddy()
            .with(TypeValidation.DISABLED)
            .rebase(commandBase, locator)
            .method(named("connect").and(takesArgument(0, InetAddress.class)))
            .intercept(MethodDelegation.to(Session3270ConnectMethod.class))
            .make()
            .load(Thread.currentThread().getContextClassLoader(), ClassLoadingStrategy.Default.INJECTION)
            .getLoaded();

//In our interceptor:
    public static void connect(InetAddress paramInetAddress,
            @Origin Method origin,
            @This Object self) throws SessionException {
        try {
            System.out.println("hi from hijacked");
            c.call();
            //HOW DO WE CALL SOMETHING LIKE super.connect()
            // we need to call Parent.connect(); 
            // but I am stuck at how to access superclass  code (new Parent().connect(). 
            // I cant access the Parent class method calls on this object
            // if I use @SuperCall or @This then I am getting already overriden version, I need to call the super (Parent's.class) version :(

        } catch (Exception e) {
            throw new RuntimeException(e);

        }
    }

Answer 1

如果我没理解错的话，您只想拦截从 class 外部而非内部调用的方法调用。

这是一件很难做到的事情。 Byte Buddy 允许您向任何 class 添加代码，但即使是手动，也很难将其编码出来。

你最好的机会可能是添加一个线程本地存储来标记这种自调用，并在拦截器再次被命中时检测它，你只需委托给超级方法而不应用拦截器逻辑。

Answer 2

public static void connect(InetAddress paramInetAddress,
            @Super Object parentObj, @This Object myself, @SuperCall Callable<?> call) throws SessionException {
        try {
            System.out.println("hi from hijacked");
            parentObj.getClass().getMethods();
            Field IMPL_LOOKUP = MethodHandles.Lookup.class.getDeclaredField("IMPL_LOOKUP");
            IMPL_LOOKUP.setAccessible(true);
            MethodHandles.Lookup lkp = (MethodHandles.Lookup) IMPL_LOOKUP.get(null);
            MethodHandle h1 = lkp.findSpecial(b.class, "connect", MethodType.methodType(void.class), Session3270.class);
            h1.invoke(myself);
        } catch (Throwable e) {
            throw new RuntimeException(e);

        }
    }

从拦截器 bytebuddy 调用超类方法

Call superclass method from interceptor bytebuddy

java

bytecode-manipulation

byte-buddy