#!/bin/sh
#
# Manage NTP configuration.
#

. /opt/puzzlefw/lib/functions.sh

# Show current configuration.
ntpcfg_show() {

    echo "Active NTP configuration:"
    if [ -s /etc/chrony/sources.d/ntp.sources ]; then
        cat /etc/chrony/sources.d/ntp.sources
    else
        echo "disabled"
    fi
    echo

    echo "Saved NTP configuration:"
    if [ -s ${CONFIG_DIR}/ntp.sources ]; then
        cat ${CONFIG_DIR}/ntp.sources
    else
        echo "disabled"
    fi
    echo
}

# Check that parameter is a well-formed IPv4 address.
check_ipaddr() {
    IFS="." read a b c d <<EOF
$1
EOF
    for i in "$a" "$b" "$c" "$d" ; do
        if ! [ "$i" -ge 0 -a "$i" -le 255 ]; then
            echo "ERROR: Invalid IP address '$1'" >&2
            exit 1
        fi
    done
}

# Configure and enable Chrony.
ntpcfg_server() {

    if [ "$1" != "server" ]; then
        echo "ERROR: Invalid command '$1'" >&2
        exit 1
    fi

    NTPSERVER="$2"

    if [ -z "$NTPSERVER" ]; then
        echo "ERROR: Server IP address not specified" >&2
        exit 1
    fi

    check_ipaddr "$NTPSERVER"

    POLLOPTS=""

    if [ "$#" -gt 2 ]; then

        if [ "$3" != "poll" ]; then
            echo "ERROR: Unknown option '$3'" >&2
            exit 1
        fi

	POLLINT="$4"

        if [ -z "$POLLINT" ]; then
            echo "ERROR: Poll interval not specified" >&2
            exit 1
        fi

        if ! [ "$POLLINT" -ge "-1" -a "$POLLINT" -le "10" ]; then
            echo "ERROR: Invalid poll interval '$POLLINT', must be between -1 and 10" >&2
            exit 1
        fi

        POLLOPTS="minpoll $POLLINT maxpoll $POLLINT"

        if [ "$#" -gt 4 ]; then
            echo "ERROR: Unexpected option '$5'" >&2
            exit 1
        fi

    fi

    # Lock to avoid conflicting changes.
    lock_config || exit 1

    echo "Configuring Chrony to start on boot with server $NTPSERVER ..."

    SERVERLINE="server $NTPSERVER $POLLOPTS iburst prefer"
    echo "$SERVERLINE" > ${CONFIG_DIR}/ntp.sources.new

    sync_config ntp.sources || exit 1

    mkdir -p /etc/chrony/sources.d
    cp -p ${CONFIG_DIR}/ntp.sources /etc/chrony/sources.d

    echo
    echo "New NTP configuration:"
    cat /etc/chrony/sources.d/ntp.sources
    echo
 
    echo "Restarting Chrony ..."
    /etc/init.d/S49chrony restart
}

# Disable starting Chrony during boot.
ntpcfg_disable() {

    # Lock to avoid conflicting changes.
    lock_config || exit 1

    echo "Disabling Chrony startup on boot ..."

    echo -n "" > ${CONFIG_DIR}/ntp.sources.new
    sync_config ntp.sources || exit 1

    echo "Stopping Chrony ..."
    /etc/init.d/S49chrony stop

    rm -f /etc/chrony/sources.d/ntp.sources
}

case "$1" in
  show)
    ntpcfg_show
    ;;
  server)
    ntpcfg_server "$@"
    ;;
  disable)
    ntpcfg_disable
    ;;
  *)
    script="${0##*/}"
    cat <<EOF
Usage: $script {server|disable|show}

Manage NTP server configuration.

  $script server {IP-address} [poll N]
    Enable starting Chrony during boot and specify NTP server to use.

    Optionally, the poll interval can be specified as a power of 2 in seconds,
    for example "poll 5" means a polling interval of 32 seconds. By default,
    the poll interval starts at 6 (64 seconds) and slowly steps up to
    10 (1024 seconds).

    Sub-millisecond accuracy can be achieved with an NTP server in the local
    network and "poll 0" (poll each second).

    Do not use a poll interval shorter than 64 seconds unless the NTP server
    is in the local network. Doing this with a public NTP server is
    considered abuse.

  $script disable
    Disable starting Chrony during boot and stop Chrony if it was running.

  $script show
    Display NTP configuration.

EOF
    exit 1
    ;;
esac

exit $?