From c90aa1692903db275c579d89ad11e211e2d51a7a Mon Sep 17 00:00:00 2001
From: Aram Sargsyan <aram@isc.org>
Date: Fri, 7 Jun 2024 16:24:00 +0000
Subject: [PATCH] Exempt prefetches from the fetches-per-server quota

Give prefetches a free pass through the quota so that the cache
entries for popular zones could be updated successfully even if the
quota for is already reached.

(cherry picked from commit c7e8b7cf63385bf642b003b09ca987ec3dc2f924)
---
 lib/dns/adb.c             | 8 ++++++--
 lib/dns/include/dns/adb.h | 4 ++++
 lib/dns/resolver.c        | 7 +++++++
 3 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/lib/dns/adb.c b/lib/dns/adb.c
index 23da59c330..a8214c9d39 100644
--- a/lib/dns/adb.c
+++ b/lib/dns/adb.c
@@ -1481,7 +1481,9 @@ copy_namehook_lists(dns_adb_t *adb, dns_adbfind_t *find, dns_adbname_t *name) {
 			dns_adbaddrinfo_t *addrinfo = NULL;
 			entry = namehook->entry;
 
-			if (adbentry_overquota(entry)) {
+			if ((find->options & DNS_ADBFIND_QUOTAEXEMPT) == 0 &&
+			    adbentry_overquota(entry))
+			{
 				find->options |= DNS_ADBFIND_OVERQUOTA;
 				goto nextv4;
 			}
@@ -1503,7 +1505,9 @@ copy_namehook_lists(dns_adb_t *adb, dns_adbfind_t *find, dns_adbname_t *name) {
 			dns_adbaddrinfo_t *addrinfo = NULL;
 			entry = namehook->entry;
 
-			if (adbentry_overquota(entry)) {
+			if ((find->options & DNS_ADBFIND_QUOTAEXEMPT) == 0 &&
+			    adbentry_overquota(entry))
+			{
 				find->options |= DNS_ADBFIND_OVERQUOTA;
 				goto nextv6;
 			}
diff --git a/lib/dns/include/dns/adb.h b/lib/dns/include/dns/adb.h
index cf725b62fc..65acb09ccf 100644
--- a/lib/dns/include/dns/adb.h
+++ b/lib/dns/include/dns/adb.h
@@ -179,6 +179,10 @@ struct dns_adbfind {
  *	This is useful for reestablishing glue that has expired.
  */
 #define DNS_ADBFIND_STARTATZONE 0x00000020
+/*%
+ *	Fetches will be exempted from the quota.
+ */
+#define DNS_ADBFIND_QUOTAEXEMPT 0x00000040
 /*%
  *      The server's fetch quota is exceeded; it will be treated as
  *      lame for this query.
diff --git a/lib/dns/resolver.c b/lib/dns/resolver.c
index 5936d16274..ded2e296fb 100644
--- a/lib/dns/resolver.c
+++ b/lib/dns/resolver.c
@@ -3263,6 +3263,13 @@ findname(fetchctx_t *fctx, const dns_name_t *name, in_port_t port,
 		options |= DNS_ADBFIND_STARTATZONE;
 	}
 
+	/*
+	 * Exempt prefetches from ADB quota.
+	 */
+	if ((fctx->options & DNS_FETCHOPT_PREFETCH) != 0) {
+		options |= DNS_ADBFIND_QUOTAEXEMPT;
+	}
+
 	/*
 	 * See what we know about this address.
 	 */