dyn-dns-dreamhost.rb

require 'open-uri'
require 'rubygems'
require 'json'

# Change these settings
hostname = 'home.hostname.com'      # the hostname you use to connect to home ip
apikey   = 'your-dreamhost-api-key' # a dreamhost api key that has access to all dns functions

# method to generate a unique_id
# TODO: use uuid instead
def unique_id 
  Time.new.to_f.to_s
end

# method to generate api url
def open_url(opts = {})
  u = "https://api.dreamhost.com/?" +
      "key=#{opts[:key]}&" +
      "cmd=#{opts[:cmd]}&" +
      "unique_id=#{unique_id}"
  u += "&format=#{opts[:format]}"       if opts[:format]
  u += "&type=a&value=#{opts[:value]}"  if opts[:value]
  u += "&record=#{opts[:record]}"       if opts[:record]
  open(u, 'UserAgent' => 'RubyWget').read
end

# retrieve current ip
ip = open('http://checkip.dyndns.com'){ |f| /([1-9]{1,3}\.){3}[0-9]{1,3}/.match(f.read)[0].to_a[0] }
puts "Current external ip: #{ip}"

# fetch the dreamhost's stored ip
dns = open_url({:key    => key, 
                :cmd    => "dns-list_records", 
                :format => 'json'})
storedIP = JSON.parse(dns).select{|d| d['record'] == hostname }.first['value']
puts "Stored ip from dreamhost for #{hostname}: #{storedIP}"

# update the dreamhost ip if it has changed
if ip == storedIP
  puts 'IP addresses match. No need to DNS'
else
  puts "IP addresses do not match, changing dreamhost ip for #{hostname} from #{storedIP} to #{ip}."
  dns = open_url({:key    => apikey, 
                  :cmd    => 'dns-remove_record', 
                  :record => hostname, 
                  :value  => storedIP})
  puts "Removed current DNS entry: #{dns}" 
  dns = open_url({:key    => apikey, 
                  :cmd    => 'dns-add_record', 
                  :record => hostname, 
                  :value  => ip})
  puts "Added new DNS entry: #{dns}" 
end