bytebuddy rebase versus subclass and wrong name/NoClassDefFoundError in OSGi - osgi

Question

I'm trying to develop an advice that wraps the actual invocation of a method. This is how I declared my interceptor:
public class SecurityInterceptor() {
#RuntimeType
public Object intercept(
#SuperCall Callable<Object> supercall,
#This Object target,
#Origin Method method,
#AllArguments Object[] args) {
// Check args and annotations ...
Object obj = supercall.call();
// use Spring SPEL to post-process obj content ...
}
}
The interceptor is registered as follows:
byte[] woven = new ByteBuddy().subclass(type)
.method(ElementMatchers.isAnnotatedWith(Secured.class))
.intercept(MethodDelegation.to(new SecurityInterceptor()))
.make().getBytes();
where the woven byte array is managed through the WeavingHook/WovenClass OSGi mechanism.
As soon as the weaved class is loaded I get the following exception:
java.lang.NoClassDefFoundError: com/contoso/users/service/provider/UsersServiceImpl (wrong name: com/contoso/users/service/provider/UsersServiceImpl$ByteBuddy$q3pXZ5KY)
at java.lang.ClassLoader.defineClass1(Native Method) ~[?:?]
at java.lang.ClassLoader.defineClass(ClassLoader.java:763) ~[?:?]
at org.apache.felix.framework.BundleWiringImpl$BundleClassLoader.defineClass(BundleWiringImpl.java:2410) ~[?:?]
at org.apache.felix.framework.BundleWiringImpl$BundleClassLoader.findClass(BundleWiringImpl.java:2194) ~[?:?]
at org.apache.felix.framework.BundleWiringImpl.findClassOrResourceByDelegation(BundleWiringImpl.java:1607) ~[?:?]
at org.apache.felix.framework.BundleWiringImpl.access$200(BundleWiringImpl.java:80) ~[?:?]
at org.apache.felix.framework.BundleWiringImpl$BundleClassLoader.loadClass(BundleWiringImpl.java:2053) ~[?:?]
at java.lang.ClassLoader.loadClass(ClassLoader.java:357) ~[?:?]
at org.apache.felix.framework.Felix.loadBundleClass(Felix.java:1927) ~[?:?]
at org.apache.felix.framework.BundleImpl.loadClass(BundleImpl.java:978) ~[?:?]
If I use the rebase method instead of the subclass one and I remove the #SuperCall Callable<Object> supercall argument, the interceptor gets called.
This error only shows up when I apply the interceptor in OSGi: the same procedure works fine in vanilla java junit tests where I modify the classes as follows:
<T> T loadTestClass(Class<T> clazz) throws Exception {
return new ByteBuddy()
.subclass(clazz)
.method(ElementMatchers.isAnnotatedWith(Secured.class))
.intercept(MethodDelegation.to(securityInterceptor))
.make()
.load(getClass().getClassLoader())
.getLoaded()
.newInstance();
}
Any idea on how to deal with this NoClassDefFoundError / wrong name error?

Answer 1

OSGi class loader implementations typically use a ClassLoader.defineClass method which takes the expected class name as an argument: e.g. https://docs.oracle.com/en/java/javase/13/docs/api/java.base/java/lang/ClassLoader.html#defineClass(java.lang.String,byte%5B%5D,int,int). When supplying the expected class name, the class loader requires the class being defined to have its name match the expected class name. This is a nice sanity check.
So if the class loader is defining the class Foo, you cannot supply the byte array for a class with a different name such as a subclass.