From f62fee2ff718aa12eaa0b697bbbee75e74a08ded Mon Sep 17 00:00:00 2001
From: redgryphon <74600987+redgryphon@users.noreply.github.com>
Date: Mon, 21 Mar 2022 00:40:43 +0100
Subject: [PATCH] Add support for NTP configuration via DHCP (fixes #689)
 (#1798)

* Add support for NTP configuration via DHCP.

* Default fallback NTP pool is the Cloudflare's one
---
 .../rootfs-overlay/etc/systemd/timesyncd.conf |  3 +-
 .../lib/NetworkManager/dispatcher.d/10-ntp    | 41 +++++++++++++++++++
 2 files changed, 42 insertions(+), 2 deletions(-)
 create mode 100644 buildroot-external/rootfs-overlay/usr/lib/NetworkManager/dispatcher.d/10-ntp

diff --git a/buildroot-external/rootfs-overlay/etc/systemd/timesyncd.conf b/buildroot-external/rootfs-overlay/etc/systemd/timesyncd.conf
index 63422d88a..43da505b3 100644
--- a/buildroot-external/rootfs-overlay/etc/systemd/timesyncd.conf
+++ b/buildroot-external/rootfs-overlay/etc/systemd/timesyncd.conf
@@ -1,3 +1,2 @@
 [Time]
-NTP=time.cloudflare.com
-FallbackNTP=0.pool.ntp.org 1.pool.ntp.org 2.pool.ntp.org 3.pool.ntp.org
+FallbackNTP=time.cloudflare.com
diff --git a/buildroot-external/rootfs-overlay/usr/lib/NetworkManager/dispatcher.d/10-ntp b/buildroot-external/rootfs-overlay/usr/lib/NetworkManager/dispatcher.d/10-ntp
new file mode 100644
index 000000000..9c815605d
--- /dev/null
+++ b/buildroot-external/rootfs-overlay/usr/lib/NetworkManager/dispatcher.d/10-ntp
@@ -0,0 +1,41 @@
+#!/bin/bash
+#
+
+TIMESYNCD_CONF=/run/systemd/timesyncd.conf.d/10-ntp.conf
+
+timesyncd_dhcp_ntp_remove() {
+  if [ -e $TIMESYNCD_CONF ]; then
+    rm -f $TIMESYNCD_CONF
+    systemctl restart systemd-timesyncd.service
+  fi
+}
+
+timesyncd_dhcp_ntp_add() {
+  mkdir -p $(dirname $TIMESYNCD_CONF)
+
+  echo '[Time]' > ${TIMESYNCD_CONF}
+  echo "NTP=${DHCP4_NTP_SERVERS}" >> ${TIMESYNCD_CONF}
+
+  systemctl restart systemd-timesyncd.service
+}
+
+INTERFACE=${1}
+ACTION=${2}
+
+case ${ACTION} in
+  up|down|dhcp4-change)
+    if [ ! -z "${DHCP4_NTP_SERVERS}" ]
+    then
+      timesyncd_dhcp_ntp_add
+      RETURN_CODE=$?
+    else
+      timesyncd_dhcp_ntp_remove
+      RETURN_CODE=$?
+    fi
+  ;;
+  *)
+    $RETURN_CODE=0
+    ;;
+esac
+
+return $RETURN_CODE