From 628e8304cc25f1995d069e6e3dfed8f574fef988 Mon Sep 17 00:00:00 2001
From: dongshengyuan <545258830@qq.com>
Date: Tue, 11 Aug 2026 20:16:45 +0800
Subject: [PATCH] resolved: notice route-only domain updates

SetLinkDomains() tracks whether the configured search domain list changed
so it can skip redundant persistence. The route_only flag is part of the
D-Bus API and is persisted as a ~ prefix, but flipping an existing domain
between search and route-only only updated in-memory state and left
changed false. The method then skipped link_save_user() and
manager_write_resolv_conf(), leaving stale state until restart.

Reproduced on Ubuntu with systemd 259:

  sudo resolvectl domain enp1s0 route-only-repro.test
  sudo resolvectl domain enp1s0 '~route-only-repro.test'
  resolvectl domain enp1s0
  grep '^DOMAINS=' /run/systemd/resolve/netif/$(cat /sys/class/net/enp1s0/ifindex)
  grep -H route-only-repro.test /run/systemd/resolve/*.conf

Before, resolvectl showed ~route-only-repro.test, but the persisted state
file still showed DOMAINS=route-only-repro.test, and the generated
resolv.conf files still contained search route-only-repro.test.

After this change, the state file is updated to
DOMAINS=~route-only-repro.test and the generated resolv.conf files are
refreshed so the route-only domain is not emitted as a search domain.

Follow-up for: cbf23f385381f1df2149b18d1fa2411356d76ad8
---
 src/resolve/resolved-link-bus.c |  5 ++++-
 test/units/TEST-75-RESOLVED.sh  | 10 ++++++++++
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/src/resolve/resolved-link-bus.c b/src/resolve/resolved-link-bus.c
index ba5b00c239..a269414ccf 100644
--- a/src/resolve/resolved-link-bus.c
+++ b/src/resolve/resolved-link-bus.c
@@ -398,7 +398,10 @@ int bus_link_method_set_domains(sd_bus_message *message, void *userdata, sd_bus_
                         changed = true;
                 }
 
-                d->route_only = route_only;
+                if (d->route_only != route_only) {
+                        d->route_only = route_only;
+                        changed = true;
+                }
         }
 
         r = sd_bus_message_exit_container(message);
diff --git a/test/units/TEST-75-RESOLVED.sh b/test/units/TEST-75-RESOLVED.sh
index ce7675e8ce..85e9e4cc84 100755
--- a/test/units/TEST-75-RESOLVED.sh
+++ b/test/units/TEST-75-RESOLVED.sh
@@ -280,6 +280,16 @@ manual_testcase_01_resolvectl() {
     resolvectl domain hoge "hoge.example.com"
     assert_in 'hoge.example.com' "$(resolvectl domain hoge)"
     assert_not_in '~.' "$(resolvectl domain hoge)"
+
+    local hoge_state
+    hoge_state="/run/systemd/resolve/netif/$(cat /sys/class/net/hoge/ifindex)"
+    resolvectl domain hoge "route-only-change.example.com"
+    assert_in "DOMAINS=route-only-change.example.com" "$(cat "$hoge_state")"
+    assert_in "route-only-change.example.com" "$(cat /run/systemd/resolve/resolv.conf /run/systemd/resolve/stub-resolv.conf)"
+    resolvectl domain hoge "~route-only-change.example.com"
+    assert_in "DOMAINS=~route-only-change.example.com" "$(cat "$hoge_state")"
+    assert_not_in "route-only-change.example.com" "$(cat /run/systemd/resolve/resolv.conf /run/systemd/resolve/stub-resolv.conf)"
+
     echo -e "nameserver 10.0.2.1\ndomain test-domain.example.com" | SYSTEMD_INVOKED_AS=resolvconf resolvectl -x -a hoge
     assert_in 'test-domain.example.com' "$(resolvectl domain hoge)"
     assert_in '~.' "$(resolvectl domain hoge)"