#!/bin/bash
DDNS_DOMAIN="myhost.mydomain.xyz"
DDNS_URL="http://abc"

WAIT_LOOP=1000
WAIT_ERROR=100
WAIT_SETTLE=10

ERROR_COUNT=0
ERROR_MAX=5

SSH_PORT=2593

function log ()
{
	echo "<${2}>${1}"
}

function refresh_ip ()
{
	log "Downloading ddns token." 6
	if /usr/bin/wget -q --tries=1 -O /dev/null "${DDNS_URL}" ; then
		log "Download of ddns token successfull." 7
		return 0
	else
		log "Download of ddns token failed." 3
		return 2
	fi
}

function check_ddns ()
{
	log "Checking name resolution." 7
	if ssh -p ${SSH_PORT} ${DDNS_DOMAIN} ; then
		log "Name resolution is up to date and works." 7
		return 0
	else
		log "Couldn't establish a connection." 4
		return 2
	fi
}

refresh_ip && sleep ${WAIT_SETTLE}
while true ; do
	if check_ddns ; then
		ERROR_COUNT=0
		sleep ${WAIT_LOOP}
	else
		if refresh_ip ; then
			sleep ${WAIT_SETTLE}
			if check_ddns ; then
				ERROR_COUNT=0
				sleep ${WAIT_LOOP}
			else
				((ERROR_COUNT++))
				sleep ${WAIT_ERROR}
			fi
		else
			((ERROR_COUNT++))
			if [ ${ERROR_COUNT} -ge ${ERROR_MAX ] ; do
				log "Too many errors, exiting." 3
				exit 42
			else
				sleep ${WAIT_ERROR}
		fi
	fi
done