docs: def process_for_rdns(self):
          """Look through my input stream for the fields in ip_field_list and
             try to do a reverse dns lookup on those fields.
          """
  
          # For each packet process the contents
          for item in self.input_stream:
  
              # Do for both the src and dst
              for endpoint in ['src', 'dst']:
  
                  # Sanity check (might be an ARP, whatever... without a src/dst)
                  if endpoint not in item['packet']:
  
                      # Set the domain to None
                      item['packet'][endpoint+self.domain_postfix] = None
                      continue
  
                  # Convert inet_address to str ip_address
                  ip_address = net_utils.inet_to_str(item['packet'][endpoint])
  
                  # Is this already in our cache
                  if self.ip_lookup_cache.get(ip_address):
                      domain = self.ip_lookup_cache.get(ip_address)
  
                  # Is the ip_address local or special
                  elif net_utils.is_internal(ip_address):
                      domain = 'internal'
                  elif net_utils.is_special(ip_address):
                      domain = net_utils.is_special(ip_address)
  
                  # Look it up at this point
                  else:
                      domain = self._reverse_dns_lookup(ip_address)
  
                  # Set the domain
                  item['packet'][endpoint+self.domain_postfix] = domain
  
                  # Cache it
                  self.ip_lookup_cache.set(ip_address, domain)
  
              # All done
              yield item