#!/bin/sh
#
# OpenIPC.org | v.20230212
# by Igor Zalatov, aka FlyRouter, aka ZigFisher
# Busybox applets: awk cat echo insmod ip modprobe sha1sum sleep tr tunctl udhcpc uptime
#


vtund_enable="1"
vtund_server=$1
vtund_server=${vtund_server:=vtun.localhost}
vtund_port="5000"
vtund_iface="tunnel"
vtund_salt=""
device_name="IPC-VTUND"
kernel_module=""
working_dir="/tmp"


identity() {
  identity_src=$(ip r | awk '/default/ {print $5}' | head -n 1)
  identity_mac=$(cat /sys/class/net/${identity_src}/address | tr 'a-z' 'A-Z')
  identity_pas=$(echo ${vtund_salt}${identity_mac} | sha1sum | awk '{print $1}')
  identity_tid=$(echo ${identity_mac} | tr -d ':')
  identity_cfg=${working_dir}/vtund.conf
}


interface() {
  [ -L /sys/class/net/${vtund_iface} ] || (modprobe tun; tunctl -t ${vtund_iface}) >/dev/null 2>&1
  [ -f ${working_dir}/udhcpc-${vtund_iface}.pid ] && kill -9 $(cat ${working_dir}/udhcpc-${vtund_iface}.pid) >/dev/null 2>&1
}


config() {
  ( echo "#"
    echo "options {"
    echo "  port ${vtund_port};"
    echo "  ifconfig /sbin/ifconfig;"
    echo "}"
    echo "${identity_tid} {"
    echo "  password ${identity_pas};"
    echo "  device ${vtund_iface};"
    echo "  stat no;"
    echo "  persist yes;"
    echo "  keepalive 10:5;"
    echo "  timeout 10;"
    echo "  up {"
    echo "    ifconfig \"${vtund_iface} hw ether ${identity_mac} mtu 1500 -multicast up\";"
    echo "    program \"udhcpc -T 1 -t 5 -R -b -O staticroutes -S -s tapip -p ${working_dir}/udhcpc-${vtund_iface}.pid -i ${vtund_iface} -x hostname:${device_name}-${identity_tid}\";"
    echo "  };"
    echo "  down {"
    echo "    ifconfig \"${vtund_iface} down\";"
    echo "  };"
    echo "}"
  ) >${identity_cfg}
}


if [ ${vtund_enable} = 1 ]; then
  (while true ; do sleep 10; identity; interface; config; vtund -n -f ${identity_cfg} ${identity_tid} ${vtund_server} >/dev/null 2>&1; done) &
fi


exit 0