#!/usr/bin/env dash
#
# Setup timesyncd to use NTP servers received by DHCP.
# Time server addresses are added or removed for each connection.
#
set -e

INTERFACE=$1
ACTION=$2
_CONF_DIR=/etc/systemd/timesyncd.conf.d

# Do we have a connection ID?
if [ -z "$CONNECTION_UUID" ]; then
    exit 0
fi

# Is the timesyncd service currently active?
_timesyncd_state="$( systemctl show --property "ActiveState" systemd-timesyncd.service )"

# Do we have the overlay configuration directory for timesyncd
if [ ! -d "$_CONF_DIR" ]; then

    # Create it
    mkdir -p "$_CONF_DIR"
fi

case $ACTION in

    # Network just went up or configuration received by DHCP has changed
    up | vpn-up | dhcp4-change | dhcp6-change)

        # Did we receive any NTP server addresses by DHCP?
        if [ -z "$DHCP4_NTP_SERVERS" ] && [ -z "$DHCP6_NTP_SERVERS" ]; then

            # Neither IPv6 nor IPv4 NTP server address received.
            exit 0
        fi

        if [ -n "$DHCP4_NTP_SERVERS" ]; then
            _ntp_servers="$_ntp_servers $DHCP4_NTP_SERVERS"
        fi
        if [ -n "$DHCP6_NTP_SERVERS" ]; then
            _ntp_servers="$_ntp_servers $DHCP6_NTP_SERVERS"
        fi

        # Create a connection-specific timesyncd configuration file
        exec > "${_CONF_DIR}/${CONNECTION_UUID}.conf"
            echo "# Generated by $(basename "$0")for $INTERFACE"
            echo "[Time]"
            echo "NTP=${_ntp_servers}"

        if [ "$_timesyncd_state" = "ActiveState=active" ]; then

            # Restart the timesyncd service
            systemctl restart systemd-timesyncd
        fi
        ;;

    # Connection went down
    down | vpn-down)

        # Remove the timesyncd configuration for this connection
        rm -f "${_CONF_DIR}/${CONNECTION_UUID}.conf"

        if [ "$_timesyncd_state" = "ActiveState=active" ]; then

            # Restart the timesyncd service
            systemctl restart systemd-timesyncd
        fi
        ;;
esac