Exception Handler: can't pickle traceback objects

[andresriancho]

The ExceptionHandler has a serious design flaw: it relies on ExceptionData having a self.traceback attribute, which is not serializable.

class ExceptionData(object):
    def __init__(self, current_status, e, tb, enabled_plugins):
        assert isinstance(e, Exception)
        assert isinstance(current_status, CoreStatus)

        #
        # According to [0] it is not a good idea to keep references to tracebacks:
        #
        #   > traceback refers to a linked list of frames, and each frame has references
        #   > to lots of other stuff like the code object, the global dict, local dict,
        #   > builtin dict, ...
        #
        # [0] https://bugs.python.org/issue13831
        #
        # TODO: Remove the next line:
        self.traceback = tb

This triggers:

Exception in thread AuditorController:
Traceback (most recent call last):
  File "/usr/lib/python2.7/threading.py", line 801, in __bootstrap_inner
    self.run()
  File "w3af/core/controllers/core_helpers/consumers/base_consumer.py", line 199, in run
    self._consume_wrapper(work_unit)
  File "w3af/core/controllers/core_helpers/consumers/base_consumer.py", line 58, in _wrapper
    result = method(self, function_id, *args, **kwds)
  File "w3af/core/controllers/core_helpers/consumers/base_consumer.py", line 227, in _consume_wrapper
    return self._consume(work_unit)
  File "w3af/core/controllers/core_helpers/consumers/audit.py", line 116, in _consume
    'audit.get_original_response()', e)
  File "w3af/core/controllers/core_helpers/consumers/base_consumer.py", line 424, in handle_exception
    self._out_queue.put(exception_data)
  File "/usr/lib/python2.7/Queue.py", line 136, in put
    self._put(item)
  File "w3af/core/data/misc/cached_queue.py", line 131, in _put
    self.disk[self.put_pointer] = item
  File "w3af/core/data/db/disk_dict.py", line 112, in __setitem__
    cpickle_dumps(value)))
  File "w3af/core/data/misc/cpickle_dumps.py", line 19, in cpickle_dumps
    return cPickle.dumps(obj, cPickle.HIGHEST_PROTOCOL)
TypeError: can't pickle traceback objects

The problem happens when one of the consumers gets an exception, the exception is handled like this:

• ExceptionData instance is created and sent to the queue (crash happens here)
• ExceptionData is read from the queue, deserialized and ExceptionHandler.handle_exception_data is called. One of the parameters used in this method is the traceback object (see: exception_data.traceback)
• Then ExceptionHandler.handle is called, where in some cases the traceback is used to re-raise the exception using raise exception, None, tb.

AFAIK there is no way to have the feature of re-raising an exception with the original traceback without having the traceback instance.