Process encrypted message bundles.

def do_POST(self):  # pylint: disable=g-bad-name
    """Process encrypted message bundles."""
    self._IncrementActiveCount()
    try:
      if self.path.startswith("/upload"):
        stats_collector_instance.Get().IncrementCounter(
            "frontend_http_requests", fields=["upload", "http"])

        logging.error("Requested no longer supported file upload through HTTP.")
        self.Send("File upload though HTTP is no longer supported", status=404)
      else:
        stats_collector_instance.Get().IncrementCounter(
            "frontend_http_requests", fields=["control", "http"])
        self.Control()

    except Exception as e:  # pylint: disable=broad-except
      if flags.FLAGS.pdb_post_mortem:
        pdb.post_mortem()

      logging.exception("Had to respond with status 500.")
      self.Send("Error: %s" % e, status=500)
    finally:
      self._DecrementActiveCount()