From: Ondřej Surý <ondrej@isc.org>
Date: Sat, 16 May 2026 11:24:53 +0000 (+0200)
Subject: Skip EDNS UDP-size hint on TCP retries
X-Git-Url: http://git.ipfire.org/gitweb/index.cgi?a=commitdiff_plain;h=08295d004ee9bdfc8fb8e59aa124e7874ae7b23b;p=thirdparty%2Fbind9.git

Skip EDNS UDP-size hint on TCP retries

The hint feeds the EDNS OPT UDP-size field, which has no effect on TCP
transport.  Avoid the dns_adb_getudpsize() lookup when the query is
already pinned to TCP.

Assisted-by: Claude:claude-opus-4-7
---

diff --git a/lib/dns/resolver.c b/lib/dns/resolver.c
index 0fc89804b80..7095143dd3a 100644
--- a/lib/dns/resolver.c
+++ b/lib/dns/resolver.c
@@ -2571,7 +2571,9 @@ resquery_send(resquery_t *query) {
 		query->options |= DNS_FETCHOPT_NOEDNS0;
 	}
 
-	if (fctx->timeout && (query->options & DNS_FETCHOPT_NOEDNS0) == 0) {
+	if (fctx->timeout && (query->options & DNS_FETCHOPT_NOEDNS0) == 0 &&
+	    (query->options & DNS_FETCHOPT_TCP) == 0)
+	{
 		isc_sockaddr_t *sockaddr = &query->addrinfo->sockaddr;
 		struct tried *tried = triededns(fctx, sockaddr);