#!/bin/sh
# This is a NetworkManager dispatcher script for chronyd to update
# its NTP sources passed from DHCP options. Note that this script is
# specific to NetworkManager-dispatcher due to use of the
# DHCP4_NTP_SERVERS environment variable.

export LC_ALL=C

interface=$1
action=$2

helper=/usr/libexec/chrony-helper
default_server_options=iburst
server_dir=/run/chrony-helper

dhcp_server_tmpfile=$server_dir/tmp-nm-dhcp.$interface
dhcp_server_file=$server_dir/nm-dhcp.$interface
# DHCP4_NTP_SERVERS is passed from DHCP options by NetworkManager.
nm_dhcp_servers=$DHCP4_NTP_SERVERS

[ -f /etc/sysconfig/network ] && . /etc/sysconfig/network
[ -f /etc/sysconfig/network-scripts/ifcfg-"${interface}" ] && \
    . /etc/sysconfig/network-scripts/ifcfg-"${interface}"

add_servers_from_dhcp() {
    rm -f "$dhcp_server_file"

    # Remove servers saved by the dhclient script before it detected NM.
    rm -f "/var/lib/dhclient/chrony.servers.$interface"

    # Don't add NTP servers if PEERNTP=no specified; return early.
    [ "$PEERNTP" = "no" ] && return

    # Create the directory with correct SELinux context.
    $helper create-helper-directory > /dev/null 2>&1

    for server in $nm_dhcp_servers; do
        echo "$server ${NTPSERVERARGS:-$default_server_options}" >> "$dhcp_server_tmpfile"
    done
    [ -e "$dhcp_server_tmpfile" ] && mv "$dhcp_server_tmpfile" "$dhcp_server_file"

    $helper update-daemon > /dev/null 2>&1 || :
}

clear_servers_from_dhcp() {
    if [ -f "$dhcp_server_file" ]; then
        rm -f "$dhcp_server_file"
        $helper update-daemon > /dev/null 2>&1 || :
    fi
}

if [ "$action" = "up" ] || [ "$action" = "dhcp4-change" ]; then
    add_servers_from_dhcp
elif [ "$action" = "down" ]; then
    clear_servers_from_dhcp
fi

exit 0