Applescript DDNS updater

DDNS.applescript

property hostname : "__domain_name__.dyndns.org"
property dyndnsUsername : "__username__"
property dyndnsPassword : "__userpassword__"
property myLastIP : missing value
property myCurrentIP : missing value
property retryPeriodSeconds : 300

on idle
    my updateDynDNS(myLastIP)
    set myLastIP to result
    return retryPeriodSeconds
end idle

on updateDynDNS(oldIP)
    try
        do shell script "dig +short myip.opendns.com @resolver1.opendns.com"
        set myCurrentIP to result
    on error errText number errNum
        log {errText, errNum}
        set myCurrentIP to missing value
    end try
    set myExternalIP to myCurrentIP
    if myExternalIP is not equal to oldIP then
        -- update dyndns
        do shell script "curl -v -k -u " & dyndnsUsername & ":" & dyndnsPassword & " \"https://members.dyndns.org/nic/update?hostname=" & hostname & "&myip=" & myExternalIP & "\" >/dev/null"
        return myExternalIP
    else
        return oldIP
    end if
end updateDynDNS