Ruby script to update dynamic DNS on Swedish LoopiaDNS.

update_loopia_dyndns.rb

#!/usr/bin/env ruby

# Updates dynamic DNS on Swedish LoopiaDNS.
# Run in crontab, e.g.:
# */15 * * * * ruby /usr/local/bin/update_loopia_dyndns.rb

USERNAME = "foo.com"
PASSWORD = "bar"
DOMAINS = %w[
  foo.com
  bar.com
  baz.com
]

IP_URL = "http://whatismyip.org/"
#IP_URL = "http://ip.fruktsallad.net/"
USER_AGENT = "UpdateLoopiaDynDNS"
STORAGE = "/tmp/external_ip"

class IPQuery
  require "open-uri"
  IP_RE = /\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}/
  
  def self.external_ip
    external_ip = open(IP_URL, "User-Agent" => USER_AGENT).read
    raise "Did not get an IP! Got: #{external_ip.inspect}" unless external_ip =~ IP_RE
    external_ip
  end
end


class LoopiaDNS
  require "net/https"
  # See http://support.loopia.co.yu/fajlovi/dynsite/loopiadns.dns
  ACCEPTABLE_RESPONSES = %w[good nochg]

  def initialize(username, password, domain)
    @username = username
    @password = password
    @domain = domain
  end

  def dyndns_ip=(ip)
    http = Net::HTTP.new('loopiadns.loopia.se', 443)
    http.use_ssl = true
    http.verify_mode = OpenSSL::SSL::VERIFY_NONE
    http.start do |http|
      request = Net::HTTP::Get.new("/XDynDNSServer/XDynDNS.php?hostname=#{@domain}&myip=#{ip}")
      request.basic_auth @username, @password
      response = http.request(request).body
      raise "Bad reply from Loopia. Reply: #{response.inspect}" unless ACCEPTABLE_RESPONSES.include?(response)
    end
  end
end


# Update IP if it has changed

external_ip = IPQuery.external_ip

unless File.exists?(STORAGE) && File.read(STORAGE) == external_ip

  DOMAINS.each do |domain|
    LoopiaDNS.new(USERNAME, PASSWORD, domain).dyndns_ip = external_ip
  end

  File.open(STORAGE, 'w') {|file| file.print external_ip }
end