From 483048b9e6daf148316c022a8bc8ba6781caee86 Mon Sep 17 00:00:00 2001
From: Franco Fichtner <franco@opnsense.org>
Date: Wed, 20 Jul 2022 14:23:54 +0200
Subject: [PATCH] dhcp: upgrade the prefix watcher to production level #5876

Just make a MD5 sum of the file and change polling to 20 seconds.
Call backend on first run as well without waiting.  Interval could
be lower still, but as said earlier it doesn't matter much all
things considered.
---
 src/opnsense/scripts/dhcp/prefixes.sh | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/src/opnsense/scripts/dhcp/prefixes.sh b/src/opnsense/scripts/dhcp/prefixes.sh
index cc900470a..45318ad7f 100755
--- a/src/opnsense/scripts/dhcp/prefixes.sh
+++ b/src/opnsense/scripts/dhcp/prefixes.sh
@@ -24,9 +24,17 @@
 # ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 # POSSIBILITY OF SUCH DAMAGE.
 
-INTERVAL=${1:-60}
+CHECKSUM="md5 -q"
+INTERVAL=${1:-20}
+LEASES="/var/dhcpd/var/db/dhcpd6.leases"
+PREVIOUS=
 
 while :; do
+	CURRENT=$(${CHECKSUM} ${LEASES})
+	if [ "${CURRENT}" != "${PREVIOUS}" ]; then
+		configctl dhcpd update prefixes
+		PREVIOUS=${CURRENT}
+	fi
+
 	sleep "${INTERVAL}"
-	configctl dhcpd update prefixes
 done