From 41208add722b0e572c1fae65b4184088a61ee3b1 Mon Sep 17 00:00:00 2001
From: cinap_lenrek <cinap_lenrek@gmx.de>
Date: Fri, 21 Jun 2013 02:27:10 +0200
Subject: [PATCH] ndb/dns: avoid duplicate entries for db records

dnauthdb() would relabel expired rr's as rr->db == 0 to make
them get garbage collected by dnage(). but this doesnt work
due to dn->keep and also causes the deduplication to fail on
rrattach() as rrattach1() handles rr->dn/rr->auth as separate
name spaces.

this causes duplicate entries in the rr's when ndb gets
gets changed. to fix, we just delete the expired (removed from
ndb) rr's immidiately in dnauthdb() instead of trying trick
dnage() to garbage collect it.
---
 sys/src/cmd/ndb/dn.c | 17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

diff --git a/sys/src/cmd/ndb/dn.c b/sys/src/cmd/ndb/dn.c
index e91183c37..ffc55ef8f 100644
--- a/sys/src/cmd/ndb/dn.c
+++ b/sys/src/cmd/ndb/dn.c
@@ -597,7 +597,7 @@ dnagedb(void)
 
 /*
  *  mark all local db records about my area as authoritative,
- *  time out any others
+ *  delete timed out ones
  */
 void
 dnauthdb(void)
@@ -606,7 +606,7 @@ dnauthdb(void)
 	ulong minttl;
 	Area *area;
 	DN *dp;
-	RR *rp;
+	RR *rp, **l;
 
 	lock(&dnlock);
 
@@ -614,19 +614,22 @@ dnauthdb(void)
 	for(i = 0; i < HTLEN; i++)
 		for(dp = ht[i]; dp; dp = dp->next){
 			area = inmyarea(dp->name);
-			for(rp = dp->rr; rp; rp = rp->next)
+			l = &dp->rr;
+			for(rp = *l; rp; rp = *l){
 				if(rp->db){
+					if(rp->expire == 0){
+						rrdelhead(l);
+						continue;
+					}
 					if(area){
 						minttl = area->soarr->soa->minttl;
 						if(rp->ttl < minttl)
 							rp->ttl = minttl;
 						rp->auth = 1;
 					}
-					if(rp->expire == 0){
-						rp->db = 0;
-						dp->referenced = now-Reserved-1;
-					}
 				}
+				l = &rp->next;
+			}
 		}
 
 	unlock(&dnlock);