From: Ronan Pigott <ronan@rjp.ie>
Date: Sat, 12 Oct 2024 17:00:56 +0000 (-0700)
Subject: resolved: update condition for caching full packets
X-Git-Tag: v257-rc1~180^2~1
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=fa02d04ee9a4787c2c39032185b6fe3e7146b26b;p=thirdparty%2Fsystemd.git

resolved: update condition for caching full packets

Previously a full packet was cached only if the CD bit was set, but this
no longer corresponds to the cases where bypass is enabled.

Update the cache to retain a full packet in the cases where it might
actually be useful.
---

diff --git a/src/resolve/resolved-dns-transaction.c b/src/resolve/resolved-dns-transaction.c
index 17a815cd446..f78bf0702b2 100644
--- a/src/resolve/resolved-dns-transaction.c
+++ b/src/resolve/resolved-dns-transaction.c
@@ -840,10 +840,8 @@ static void dns_transaction_cache_answer(DnsTransaction *t) {
                       dns_transaction_key(t),
                       t->answer_rcode,
                       t->answer,
-                      DNS_PACKET_CD(t->received) ? t->received : NULL, /* only cache full packets with CD on,
-                                                                        * since our use case for caching them
-                                                                        * is "bypass" mode which is only
-                                                                        * enabled for CD packets. */
+                      /* If neither DO nor EDE is set, the full packet isn't useful to cache */
+                      DNS_PACKET_DO(t->received) || t->answer_ede_rcode > 0 || t->answer_ede_msg ? t->received : NULL,
                       t->answer_query_flags,
                       t->answer_dnssec_result,
                       t->answer_nsec_ttl,