[PATCH] wg-quick: darwin: fix set_dns() and del_dns() race

[Dmitry Ilvokhin <d@ilvokhin.com>]

The monitor deamon restores the DNS servers by running del_dns() from
its INT, TERM and EXIT trap. Every route event also schedules an ALRM 2
seconds later, and the ALRM trap runs set_dns().

If ALRM arrives during cleanup, set_dns() can run in the middle of
del_dns(), and the DNS servers may not be restored after the WireGuard
interface is removed.

Ignore ALRM in cleanup signal handler to avoid this race.

Signed-off-by: Dmitry Ilvokhin <d@ilvokhin.com>
---
 src/wg-quick/darwin.bash | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/wg-quick/darwin.bash b/src/wg-quick/darwin.bash
index 0179afb..20a21ce 100755
--- a/src/wg-quick/darwin.bash
+++ b/src/wg-quick/darwin.bash
@@ -323,7 +323,7 @@ del_dns() {
 
 monitor_daemon() {
 	echo "[+] Backgrounding route monitor" >&2
-	(trap 'del_routes; del_dns; exit 0' INT TERM EXIT
+	(trap 'trap "" ALRM; del_routes; del_dns; exit 0' INT TERM EXIT
 	exec >/dev/null 2>&1
 	exec 19< <(exec route -n monitor)
 	local event bpid=$BASHPID mpid=$!
-- 
2.54.0 (Apple Git-157)