Deserializing to a completely different classname ?

Question

Hi,
I'm trying to read in a serialized obfuscated class,
and dynamically replace it with an unobfuscated version.
The classnames, method names & field names are different, but the field types are the same.
Any ideas ? Or is it possible at all ?
any help appreciated,
cheers,
Owen
I tried the following subclass of ObjectInputStream
class MyObjectInputStream extends ObjectInputStream
  public MyObjectInputStream ( InputStream is ) throws IOException
     super ( is );
     enableResolveObject ( true );
  protected Class resolveClass(ObjectStreamClass v)
        throws IOException, ClassNotFoundException
     String classname = v.getName();
     if ( classname.equalsIgnoreCase ( "Obfuscated" ) )
     Class newClass = Class.forName ( "Deobfuscated" );
     return ( newClass );
     else
     return ( super.resolveClass ( v ) );
}but end up getting the following stack trace
java.io.InvalidClassException: Deobfuscated;
Incompatible local class name. Expected class name compatible with Obfuscated
at java.io.ObjectStreamClass.validateLocalClass(ObjectStreamClass.java:528)
at java.io.ObjectStreamClass.setClass(ObjectStreamClass.java:562)
at java.io.ObjectInputStream.inputClassDescriptor(ObjectInputStream.java:931)
at java.io.ObjectInputStream.readObject(ObjectInputStream.java:361)
at java.io.ObjectInputStream.readObject(ObjectInputStream.java:231)
at java.io.ObjectInputStream.inputObject(ObjectInputStream.java:1181)
at java.io.ObjectInputStream.readObject(ObjectInputStream.java:381)
at java.io.ObjectInputStream.readObject(ObjectInputStream.java:231)
at TestOut.TestIn(TestOut.java:38)
at TestOut.main(TestOut.java:100)

Answer 1

I'll post the code in case anyone is curious.
Exception handling could be better in places...
cheers,
Owen
class DeobfuscateObjectInputStream extends ObjectInputStream
     public DeobfuscateObjectInputStream ( InputStream is ) throws IOException, Exception
          super ( is );
          enableResolveObject ( true );
    protected Object resolveObject(Object obj) throws IOException
        deobfuscate ( obj )
    public Object deobfuscate ( Object srcObject ) throws IOException
        Class srcClass = srcObject.getClass();
        if ( srcClass.getName().equalsIgnoreCase ( "Obfuscated" ) )
            try
                String destClassName = "Deobfuscated";  // deobfuscated class name
                Field[] srcFields = srcClass.getDeclaredFields();
                Class destClass = Class.forName ( destClassName );
                // serializable class must have an empty parameter constructor
                Object destObj = destClass.newInstance(); 
                if ( srcFields != null )
                    for ( int i=0; i<srcFields.length; i++ )
                        Field srcField  = srcFields;
Field destField = null;
try
// assumes source field name in dest field name at the moment...
destField = destClass.getDeclaredField ( srcFields[i].getName() );
int destFieldModifiers = destField.getModifiers();
int srcFieldModifiers = srcField.getModifiers();
if ( Modifier.isPrivate ( srcFieldModifiers ) )
try
srcField.setAccessible ( true );
catch ( SecurityException secEx )
System.out.println ("Security Exception : Cannot access source private variable : " + srcField.getName() );
if ( Modifier.isPrivate ( destFieldModifiers ) )
try
destField.setAccessible ( true );
catch ( SecurityException secEx )
System.out.println ("Security Exception : Cannot access dest private variable : " + destField.getName() );
if ( !Modifier.isFinal ( destFieldModifiers ) && !Modifier.isStatic ( destFieldModifiers ) )
try
destField.set ( destObj, srcField.get( srcObject ) );
System.out.println ( destField.getName() );
catch ( IllegalAccessException iex )
if ( Modifier.isPrivate ( destFieldModifiers ) )
System.out.println ( "[ error field \"" + destField.getName() + "\" is private ]" );
else
System.out.println ( "[ error attempting to set field \"" + destField.getName() + "\"  ]" );
else
if ( !Modifier.isFinal ( destFieldModifiers ) )
System.out.println ("[ skipped - is final in dest class ]");
else
System.out.println ("[ skipped - is static in dest class ]");
catch ( NoSuchFieldException ex )
System.out.println ("[ ERROR - doesnt exist in dest class]");
return ( destObj );
else
System.out.println ("\tNo Fields");
return ( destObj );
catch ( Exception ex )
ex.printStackTrace();
// convert except to IOException for resolveObject
throw ( new IOException ( ex.getMessage() ) );
else
return ( srcObject );