From: Ondřej Surý <ondrej@isc.org>
Date: Tue, 26 Aug 2025 15:52:45 +0000 (+0200)
Subject: Preserve ZEROTTL attribute when replacing NS RRset
X-Git-Tag: v9.21.12~22^2~1
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=982ca161c26c2e6cd90b19888331bb015dcbae1f;p=thirdparty%2Fbind9.git

Preserve ZEROTTL attribute when replacing NS RRset

Previously, BIND 9 would drop the ZEROTTL attribute when updating
previously cached NS entry with ZEROTTL attribute set.

Co-authored-by: Jinmei Tatuya <jtatuya@infoblox.com>
---

diff --git a/lib/dns/qpcache.c b/lib/dns/qpcache.c
index 6ced85532d6..ecb2b11eac1 100644
--- a/lib/dns/qpcache.c
+++ b/lib/dns/qpcache.c
@@ -2790,6 +2790,11 @@ find_header:
 		    header->trust <= newheader->trust)
 		{
 			if (newheader->expire > header->expire) {
+				if (ZEROTTL(header)) {
+					DNS_SLABHEADER_SETATTR(
+						newheader,
+						DNS_SLABHEADERATTR_ZEROTTL);
+				}
 				newheader->expire = header->expire;
 			}
 		}