Simple DDNS script for Hurricane Electric (dns.he.net)

he-ddns.sh

#!/bin/sh -e
#
# Hurricane Electric DDNS script for OpenWrt
#
# crontab: */5 * * * * INTERFACE=pppoe-wan USE_PEERDNS=1 DOMAIN=example.com KEY=password /usr/bin/he-ddns.sh
#
set -o pipefail

INTERFACE="${INTERFACE:-pppoe-wan}"
DOMAIN="${DOMAIN:-example.com}"
KEY="${KEY:-password}"
USE_PEERDNS="${USE_PEERDNS:-0}"

get_interface_ipv4() {
  ip addr show dev "$1" | grep -w "inet" | awk '{print $2}' | awk -F '/' '{print $1}'
}

get_interface_ipv6() {
  ip addr show dev "$1" | grep -w "inet6" | awk '{print $2}' | awk -F '/' '{print $1}'
}

get_domain_ipv4() {
  nslookup "$1" $([ "$USE_PEERDNS" = 1 ] && get_peerdns) | grep "Address 1:" | awk '{print $3}'
}

get_domain_ipv6() {
  nslookup -query=AAAA "$1" $([ "$USE_PEERDNS" = 1 ] && get_peerdns) | grep "has AAAA address" | awk '{print $5}' | head -1
}

get_peerdns() {
  [ -f /tmp/resolv.conf.ppp ] && cat /tmp/resolv.conf.ppp | awk '{print $2}' | head -1
}

ip_updatable() {
  local interface_ip="$1"
  local domain_ip="$2"
  [ -z "$interface_ip" ] && return 1
  [ "$interface_ip" = "$domain_ip" ] && return 1
  return 0
}

do_update() {
  local update_url="$1"
  for i in $(seq 1 10)
  do
    if wget -q -T 10 -O - "$update_url"; then
      break
    fi
    sleep 3
  done
}

update_ddns() {
  local interface_ipv4="$(get_interface_ipv4 $INTERFACE)"
  local interface_ipv6="$(get_interface_ipv6 $INTERFACE)"
  local domain_ipv4="$(get_domain_ipv4 $DOMAIN)"
  local domain_ipv6="$(get_domain_ipv6 $DOMAIN)"
  local update_url_ipv4="https://dyn.dns.he.net/nic/update?hostname=${DOMAIN}&password=${KEY}&myip=${interface_ipv4}"
  local update_url_ipv6="https://dyn.dns.he.net/nic/update?hostname=${DOMAIN}&password=${KEY}&myip=${interface_ipv6}"

  if ip_updatable "$interface_ipv4" "$domain_ipv4"; then
    do_update "$update_url_ipv4"
  fi

  if ip_updatable "$interface_ipv6" "$domain_ipv6"; then
    do_update "$update_url_ipv6"
  fi
}

update_ddns