#!/bin/bash
#
# Copyright 2023 Collier Technologies LLC
# https://wp.c9h.org/cj/?p=1844
#

# # These variables are for the use of the scripts run by run-parts
# PPP_IFACE="$1"
# PPP_TTY="$2"
# PPP_SPEED="$3"
# PPP_LOCAL="$4"
# PPP_REMOTE="$5"
# PPP_IPPARAM="$6"
set -x

PPP_IFACE=${PPP_IFACE:="ppp0"}
if [[ -z ${PPP_LOCAL} ]]; then
    PPP_LOCAL=$(curl -s https://icanhazip.com/)
fi

date +"%FT%T"

#printf "%x%x:%x%x\n" $(echo $PPP_LOCAL | tr . ' ')

# This configuration option came from CenturyLink:
# https://www.centurylink.com/home/help/internet/modems-and-routers/advanced-setup/enable-ipv6.html
border_router=205.171.2.64

TUNIFACE=6rdif

first_ipv6_network=$(printf "2602:%02x:%02x%02x:%02x00::" $(echo ${PPP_LOCAL} | tr . ' '))

ip tunnel add ${TUNIFACE} mode sit local ${PPP_LOCAL} remote ${border_router}
ip tunnel 6rd dev ${TUNIFACE} 6rd-prefix "${first_ipv6_network}0/64" 6rd-relay_prefix ${border_router}/32
ip link set up dev ${TUNIFACE}
ip -6 route add default dev ${TUNIFACE}

ip addr add ${first_ipv6_network}1/64 dev ${TUNIFACE}

rm /etc/radvd.conf
i=1
DEFAULT_FILE="/etc/default/centurylink-6rd"
if [[ -f ${DEFAULT_FILE} ]]; then
    source ${DEFAULT_FILE}
    if [[ -f ${HEADER_FILE} ]]; then
	cp ${HEADER_FILE} /etc/radvd.conf
    fi
else
    LAN_IFACE="setThis"
fi
   
for IFACE in $( echo ${LAN_IFACE} | tr , ' ' ) ; do

    ipv6_network=$(printf "2602:%02x:%02x%02x:%02x0${i}::" $(echo ${PPP_LOCAL} | tr . ' '))

    ip addr add ${ipv6_network}1/64 dev ${TUNIFACE}
    ip -6 route replace "${ipv6_network}/64" dev ${IFACE} metric 1

    echo "
interface ${IFACE} {
   AdvSendAdvert on;
   MinRtrAdvInterval 3;
   MaxRtrAdvInterval 10;
   AdvLinkMTU 1280;
   prefix ${ipv6_network}/64 {
     AdvOnLink on;
     AdvAutonomous on;
     AdvRouterAddr on;
     AdvValidLifetime 86400;
     AdvPreferredLifetime 86400;
   };
};
" >> /etc/radvd.conf

    let "i=i+1"
done

systemctl restart radvd
set +x