#! /bin/bash

# This script will determine the current IPv6 address of the host and call
# an external URL to update the dynamic dns entry

user=""
password=""
server_url=""

if [ -e /tmp/dnsping_oldaddr ];
then
	old_addr=$(cat /tmp/dnsping_oldaddr)
else
	old_addr=""
fi

new_addr=$(ip -o -6 addr | grep -v -e fc00:: -e fd00:: | grep global | grep -v "preferred_lft 0sec" | grep -v temporary | awk '{print $4}' | cut -d "/" -f 1)

if [ "$old_addr" != "$new_addr" ];
then
	if [ ! -z "$new_addr" ];
	then
		echo "detected new ip address: $new_addr"
		curl --user ${user}:${password} "https://${server_url}/?ipv6=$new_addr"
		echo "$new_addr" > /tmp/dnsping_oldaddr
	fi
fi