wg-quick: freebsd: use ifconfig for determining if interface is up

We no longer need the arp hack, as these bugs have been fixed in the
FreeBSD kernel.

This partially reverts 090639ae90fb45ac05e3158e1e31e5bf15fd9559.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

1 files changed, 2 insertions, 16 deletions

diff --git a/src/wg-quick/freebsd.bash b/src/wg-quick/freebsd.bash
index e00f1e1..e731384 100755
--- a/src/wg-quick/freebsd.bash
+++ b/src/wg-quick/freebsd.bash
@@ -152,20 +152,6 @@ del_routes() {
 	done
 }
 
-if_exists() {
-	# HACK: The goal is simply to determine whether or not the interface exists. The
-	# straight-forward way of doing this would be `ifconfig $INTERFACE`, but this
-	# invokes the SIOCGIFSTATUS ioctl, which races with interface shutdown inside
-	# the tun driver, resulting in a kernel panic. So we work around it the stupid
-	# way by using the one utility that appears to call if_nametoindex fairly early
-	# and fails if it doesn't exist: `arp`.
-	if arp -i "$INTERFACE" -a -n >/dev/null 2>&1; then
-		return 0
-	else
-		return 1
-	fi
-}
-
 del_if() {
 	[[ $HAVE_SET_DNS -eq 0 ]] || unset_dns
 	if [[ -S /var/run/wireguard/$INTERFACE.sock ]]; then
@@ -173,7 +159,7 @@ del_if() {
 	else
 		cmd ifconfig "$INTERFACE" destroy
 	fi
-	while if_exists; do
+	while ifconfig "$INTERFACE" >/dev/null 2>&1; do
 		# HACK: it would be nice to `route monitor` here and wait for RTM_IFANNOUNCE
 		# but it turns out that the announcement is made before the interface
 		# disappears so we sometimes get a hang. So, we're instead left with polling
@@ -305,7 +291,7 @@ monitor_daemon() {
 	# endpoints change.
 	while read -r event; do
 		[[ $event == RTM_* ]] || continue
-		if_exists || break
+		ifconfig "$INTERFACE" >/dev/null 2>&1 || break
 		[[ $AUTO_ROUTE4 -eq 1 || $AUTO_ROUTE6 -eq 1 ]] && set_endpoint_direct_route
 		# TODO: set the mtu as well, but only if up
 	done < <(route -n monitor)) & disown