#!/bin/sh
passwd='dyndnshosts'
hostname=$(hostname | tr '[:upper:]' '[:lower:]')

platform='unknown'
unamestr=$(uname)
if [ "$unamestr" = 'Linux' ]; then
  platform='linux'
elif [ "$unamestr" = 'FreeBSD' ]; then
  platform='freebsd'
fi

ip6addr=''
ip4addr=''
if [ $platform = 'linux' ]; then
  ip6addr=$(ip -6 addr show scope global | grep inet6 | tail -1 | egrep -o '([0-9abcdef]{4}[0-9:abcdef]*)')
  # filter local IPv4 address ranges (172.16.0.0/12, 10.0.0.0/8, 192.168.0.0/16)
  ip4addr=$(ip -4 addr show scope global | grep inet | egrep -o '([0-9]{1,3}\.){3}[0-9]{1,3}' | grep -Ev '172.(1[6-9]|2[0-9]|3[0-1])' | grep -Ev '10.' | grep -Ev '192.168.' | head -n 1)
elif [ $platform = 'freebsd' ]; then
  ip6addr=$(ifconfig em0 | grep inet6 | tail -1 | egrep -o '([0-9abcdef]{4}[0-9:abcdef]*)')
  ip4addr=$(ifconfig em0 inet | grep inet | egrep -o '([0-9]{1,3}\.){3}[0-9]{1,3}' | head -n 1)
fi

echo "Current IP addresses of $hostname are: $ip4addr, $ip6addr"


if [ $ip4addr ]; then
  echo "Updating IPv4 DNS entry..."
else
  echo "No public IPv4 address, updating DNS entry anyway..."
fi

# API always returns 200, so check for response payload to begin with {"Success":true,
url="https://dyndns.jtbx.de/update?secret=$passwd&domain=$hostname&addr=$ip4addr"
statuscode=$(curl -s $url)
case "$statuscode" in
  {\"Success\":true*) echo "IPv4 Success" ;;
  *) (>&2 echo "IPv4 DynDNS update failed: API response:\n$statuscode") ;;
esac


if [ $ip6addr ]; then
  echo "Updating IPv6 DNS entry..."

  # API always returns 200, so check for response payload to begin with {"Success":true,
  url="https://dyndns.jtbx.de/update?secret=$passwd&domain=$hostname&addr=$ip6addr"
  statuscode=$(curl -s $url)
  case "$statuscode" in
    {\"Success\":true*) echo "IPv6 Success" ;;
    *) (>&2 echo "IPv6 DynDNS update failed: API response:\n$statuscode") ;;
  esac
else
  echo "No public IPv6 Address, skipping DNS update."
fi