#!/bin/bash
# NetworkManager dispatcher: feed DHCP option 42 (NTP servers) into chrony.
#
# Replaces the old dhclient.d/chrony.sh bridge — we use NetworkManager's internal
# DHCP now (the network-manager dracut port), and NM exports the lease's NTP
# servers to dispatcher scripts as $DHCP4_NTP_SERVERS. chrony.conf carries
# `sourcedir /run/chrony-dhcp`, so writing <iface>.sources there and reloading
# makes chronyd use the DHCP-provided server. The image's baked public pool is
# stripped (see the provisioner), so the host syncs ONLY from the lab NTP server
# — no time egress from the workstation.
#
# Installed 0755 root:root at /etc/NetworkManager/dispatcher.d/. Lenient on
# purpose: a hiccup here must never break networking.

interface="$1"
action="$2"

case "$action" in
    up|dhcp4-change|reapply) ;;
    *) exit 0 ;;
esac

dir=/run/chrony-dhcp
file="$dir/${interface}.sources"
mkdir -p "$dir"

if [ -n "${DHCP4_NTP_SERVERS:-}" ]; then
    : > "$file"
    for s in $DHCP4_NTP_SERVERS; do
        printf 'server %s iburst\n' "$s" >> "$file"
    done
    # Pick up the new sources without restarting chronyd.
    chronyc reload sources >/dev/null 2>&1 || true
fi

exit 0