#!/bin/sh
#
# Start the `FRP server' as a daemon, and start/check with a cron job.
# https://github.com/fatedier/frp
#
# See start-stop-daemon(8) for details.
# The `start-stop-daemon' tool is shipped with the `dpkg' package on
# Debian systems, which is an essential part.  While on non-Debian
# systems, e.g., RedHat/CentOS, install the `dpkg' package to get this
# tool ;)
#
#
# Example configuration file:
# ---------------------------------------------------------------------
# [common]
# bind_port = xxxx
# ---------------------------------------------------------------------
#
# Example cron job (check every 10th minutes):
# */10  *  *  *  *  sh $HOME/bin/frps-daemon.sh start >/dev/null 2>&1
#
# NOTE:
# * If the machine that runs this `FRP server' is behind a NAT, then
#   port forwarding for the above `bind_port' should be enabled.
# * For each service that FRP proxies, e.g., SSH, an extra port will
#   be bind to the server-side machine, as specified by the `remote_port'
#   in the client-side configuration file.
# * With only `bind_port' been forwarded, one can SSH into the server-side
#   machine first, then SSH into the client-side machine through:
#       ssh -p <remote_port> <user>@localhost
# * With the extra `remote_port' been also forwarded, one can simply
#   SSH into the client-side machine with:
#       ssh -p <remote_port> <user>@<ip_server_side>
#
#
# Aaron LI
# 2018-01-23
#

NAME=frps
PROGRAM=$HOME/local/frp/frps
CONFIG=$HOME/configs/${NAME}.ini
PIDFILE=$HOME/.cache/${NAME}.pid
LOGFILE=$HOME/.cache/${NAME}.log

PATH=${PATH}:/usr/local/sbin:/usr/sbin:/sbin

case "$1" in
    start)
        cmd=start
        cmd_args="--start --make-pidfile --background"
        ;;
    stop)
        cmd=stop
        cmd_args="--stop --remove-pidfile --retry 5"
        ;;
    status)
        cmd=status
        cmd_args="--status"
        ;;
    *)
        echo "usage: ${0##*/} {start|stop|status}"
        exit 1
        ;;
esac

start-stop-daemon ${cmd_args} \
    --oknodo --verbose \
    --name ${NAME} \
    --pidfile ${PIDFILE} \
    --startas ${PROGRAM} \
    -- -c ${CONFIG} -L ${LOGFILE}
ret=$?
if [ "${cmd}" = "start" ]; then
    if [ ${ret} -eq 0 ]; then
        echo "Successfully started ${NAME} as PID $(cat ${PIDFILE})"
    else
        echo "Failed to start ${NAME}: ${PROGRAM}"
        echo "Exit code: ${ret}"
    fi
elif [ "${cmd}" = "stop" ]; then
    if [ ${ret} -eq 0 ]; then
        echo "Successfully stopped ${NAME}: ${PROGRAM}"
    else
        echo "Failed to stop ${NAME}: ${PROGRAM}"
        echo "Exit code: ${ret}"
    fi
elif [ "${cmd}" = "status" ]; then
    if [ ${ret} -eq 0 ]; then
        echo "${NAME} is running as PID $(cat ${PIDFILE})"
    elif [ ${ret} -eq 1 ]; then
        echo "${NAME} is not running but the PID file (${PIDFILE}) exists"
    elif [ ${ret} -eq 3 ]; then
        echo "${NAME} is not running"
    else
        echo "${NAME} in unknown status"
        echo "Exit code: ${ret}"
    fi
else
    echo "ERROR: unknown command: ${cmd}"
fi