refreshing the dns cache

[Mark_Andrews at isc.org]

> Hi all,
> 
> I am a loyal user of BIND8 for over two years and I handled about hundred of
> cases regarding our DNS cache servers cached wrong information. Usually they
> were due to 3rd party DNS administers mistake but I know my customers are
> the victims and I can't tell them just to wait.
> 
> To make the story short, my point is I usually erase the part of the cache
> that is outdated if I got wrong caching complain. The way I did it in BIND8
> is to create the zone which is exactly the same as the cached zone/domain.
> After I reload the named, I remove the zone from the config file and reload
> it again. It is ugly but my customers are happy.
> 
> Things do not go well in BIND9 and I found out it is because the cache and
> the local zones are stored in two (or more if there are more than one view)
> databases. I am in the midst of creating a new rndc command such that it
> will check all the cache database and remove the cached domain.
> 
> However, I am stuck at trying to convert the domain name into the object
> dns_name_t. Unfortunately I have little clue after reading quite a lot of
> the source code.
> 
> Appended is my code so far, would appreciate if anyone can enlighten me
> on it? Hope I can contribute to the BIND community. :) BTW, does ISC
> has a plan to put this feature into the release?
> 
> isc_result_t
> ns_server_rmcache(ns_server_t *server, char *args) {
>         isc_result_t result;
>         dns_zone_t *zone = NULL;
>         dns_zonetype_t type;
>         char *input, *ptr;
>         const char *zonetxt;
>         FILE *fp = NULL;
>         dns_view_t *view;
> 
>         input = args;
> 
>         /* Skip the command name and extract the zone name. */
>         ptr = next_token(&input, " \t");
>         if (ptr == NULL)
>                 result = ISC_R_UNEXPECTEDEND;
> 
>         /* Look for the zone name. */
>         zonetxt = next_token(&input, " \t");
>         result = ISC_R_SUCCESS;
> 
>         if (result != ISC_R_SUCCESS)
>                 return (result);
>         if (zonetxt == NULL) {
>                 isc_log_write(ns_g_lctx, NS_LOGCATEGORY_GENERAL,
>                               NS_LOGMODULE_SERVER, ISC_LOG_ERROR,
>                               "rmcache zones failed: %s", zonetxt);
>         } else {
>                 for (view = ISC_LIST_HEAD(server->viewlist);
>                      view != NULL;
>                      view = ISC_LIST_NEXT(view, link))
>                 {
>                         if (view->cachedb != NULL) {
> /*********************************
> /* here is the part I have problem
> /*********************************
> 
>                                 dns_db_findnode(view->cachedb, name,
> ISC_FALSE,
> &node);
> 
>                                 dns_db_detachnode(db, node);
>                         }
>                         /* else, it is not cachedb, next */
>                 }
>                 isc_log_write(ns_g_lctx, NS_LOGCATEGORY_GENERAL,
>                               NS_LOGMODULE_SERVER, ISC_LOG_ERROR,
>                               "rmcache zones succeed: %s", args);
>         }
>         return (ISC_R_SUCCESS);
>  cleanup:
>         if (fp != NULL)
>                 (void)isc_stdio_close(fp);
>         return (result);
> }
> 
> 
> 
> 
> 
> 

	It's already available in the 9.3 snapshot.

	Mark

Usage: rndc [-c config] [-s server] [-p port]
        [-k key-file ] [-y key] [-V] command

command is one of the following:

  reload	Reload configuration file and zones.
  reload zone [class [view]]
		Reload a single zone.
  refresh zone [class [view]]
		Schedule immediate maintenance for a zone.
  retransfer zone [class [view]]
		Retransfer a single zone without checking serial number.
  freeze zone [class [view]]
  		Suspend updates to a dynamic zone.
  unfreeze zone [class [view]]
  		Enable updates to a frozen dynamic zone and reload it.
  reconfig	Reload configuration file and new zones only.
  stats		Write server statistics to the statistics file.
  querylog	Toggle query logging.
  dumpdb	Dump cache(s) to the dump file (named_dump.db).
  stop		Save pending updates to master files and stop the server.
  stop -p	Save pending updates to master files and stop the server
		reporting process id.
  halt		Stop the server without saving pending updates.
  halt -p	Stop the server without saving pending updates reporting
		process id.
  trace		Increment debugging level by one.
  trace level	Change the debugging level.
  notrace	Set debugging level to 0.
  flush 	Flushes all of the server's caches.
  flush [view]	Flushes the server's cache for a view.
  flushname name [view]
		Flush the give name from the server's cache(s)
  status	Display status of the server.
  *restart	Restart the server.

* == not yet implemented
Version: 9.3.0a0
--
Mark Andrews, Internet Software Consortium
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: Mark.Andrews at isc.org