From 6594f7acb2c48819f49e70871df588b7a82ae0a8 Mon Sep 17 00:00:00 2001
From: Matthijs Mekking <matthijs@isc.org>
Date: Fri, 8 Feb 2019 16:20:47 +0100
Subject: [PATCH] Remove rpz->db_registered

As pointed out in !813 db_registered is sort of redundant.  It is
set to `true` only in `dns_zone_rpz_enable_db()` right before the
`dns_rpz_dbupdate_callback()` callback is registered.  It is only
required in that callback and it is the only place that the callback
is registered.  Therefore there is no path that that `REQUIRE` can
fail.

The `db_registered` variable is only set to `false` in
`dns_rpz_new_zone`, so it is not like the variable is unset again
later.

The only other place where `db_registered` is checked is in
`rpz_detach()`.  If `true`, it will call
`dns_db_updatenotify_unregister()`.  However if that happens, the
`db_registered` is not set back to `false` thus this implies that
this may happen multiple times.  If called a second time, most
likely the unregister function will return `ISC_R_NOTFOUND`, but
the return value is not checked anyway.  So it can do without the
`db_registered` check.
---
 lib/dns/include/dns/rpz.h | 5 ++---
 lib/dns/rpz.c             | 8 ++------
 lib/dns/zone.c            | 1 -
 3 files changed, 4 insertions(+), 10 deletions(-)

diff --git a/lib/dns/include/dns/rpz.h b/lib/dns/include/dns/rpz.h
index 0c12da6e9d..e8f5170ca7 100644
--- a/lib/dns/include/dns/rpz.h
+++ b/lib/dns/include/dns/rpz.h
@@ -144,15 +144,14 @@ struct dns_rpz_zone {
 	isc_ht_t	 *nodes;	/* entries in zone */
 	dns_rpz_zones_t	 *rpzs;		/* owner */
 	isc_time_t	 lastupdated;	/* last time the zone was processed */
-	bool	 updatepending;	/* there is an update pending/waiting */
-	bool	 updaterunning;	/* there is an update running */
+	bool	 	 updatepending;	/* there is an update pending/waiting */
+	bool	 	 updaterunning;	/* there is an update running */
 	dns_db_t	 *db;		/* zones database */
 	dns_dbversion_t	 *dbversion;	/* version we will be updating to */
 	dns_db_t	 *updb;		/* zones database we're working on */
 	dns_dbversion_t	 *updbversion;	/* version we're currently working on */
 	dns_dbiterator_t *updbit;	/* iterator to use when updating */
 	isc_ht_t	 *newnodes;	/* entries in zone being updated */
-	bool	 db_registered;	/* is the notify event registered? */
 	isc_timer_t	 *updatetimer;
 	isc_event_t	 updateevent;
 };
diff --git a/lib/dns/rpz.c b/lib/dns/rpz.c
index d7112b01ed..83f8f7d6c5 100644
--- a/lib/dns/rpz.c
+++ b/lib/dns/rpz.c
@@ -1549,7 +1549,6 @@ dns_rpz_new_zone(dns_rpz_zones_t *rpzs, dns_rpz_zone_t **rpzp) {
 	zone->updbversion = NULL;
 	zone->updbit = NULL;
 	zone->rpzs = rpzs;
-	zone->db_registered = false;
 	ISC_EVENT_INIT(&zone->updateevent, sizeof(zone->updateevent),
 		       0, NULL, 0, NULL, NULL, NULL, NULL, NULL);
 
@@ -1584,7 +1583,6 @@ dns_rpz_dbupdate_callback(dns_db_t *db, void *fn_arg) {
 	REQUIRE(zone != NULL);
 
 	LOCK(&zone->rpzs->maint_lock);
-	REQUIRE(zone->db_registered);
 
 	/* New zone came as AXFR */
 	if (zone->db != NULL && zone->db != db) {
@@ -2100,10 +2098,8 @@ rpz_detach(dns_rpz_zone_t **rpzp, dns_rpz_zones_t *rpzs) {
 		dns_db_closeversion(rpz->db, &rpz->dbversion, false);
 	}
 	if (rpz->db != NULL) {
-		if (rpz->db_registered) {
-			dns_db_updatenotify_unregister(
-				rpz->db, dns_rpz_dbupdate_callback, rpz);
-		}
+		dns_db_updatenotify_unregister(
+			rpz->db, dns_rpz_dbupdate_callback, rpz);
 		dns_db_detach(&rpz->db);
 	}
 	if (rpz->updaterunning) {
diff --git a/lib/dns/zone.c b/lib/dns/zone.c
index 457e47b927..28f353a2ea 100644
--- a/lib/dns/zone.c
+++ b/lib/dns/zone.c
@@ -1786,7 +1786,6 @@ dns_zone_rpz_enable_db(dns_zone_t *zone, dns_db_t *db) {
 	if (zone->rpz_num == DNS_RPZ_INVALID_NUM)
 		return;
 	REQUIRE(zone->rpzs != NULL);
-	zone->rpzs->zones[zone->rpz_num]->db_registered = true;
 	result = dns_db_updatenotify_register(db,
 					      dns_rpz_dbupdate_callback,
 					      zone->rpzs->zones[zone->rpz_num]);