gandi-ddns.py

from __future__ import print_function
try:
  from xmlrpc import client as xmlrpclient
  from urllib.request import urlopen
  import configparser
except ImportError:
  from urllib2 import urlopen
  import xmlrpclib as xmlrpclient
  import ConfigParser as configparser
import sys
import os
import socket

# Used to cache the zone_id for future calls
zone_id = None

# name of the configuration file.
# If the full path is not given, gandi-ddns.py will check for this file in
# its current directory
config_file = "config.txt"

SCRIPT_DIR = os.path.dirname(os.path.realpath(__file__))

def get_zone_id(config, section):
	""" Get the gandi.net ID for the current zone version"""

	global zone_id
	
	# If we've not already got the zone ID, get it
	if zone_id is None:
		# Get domain info then check for a zone
		domain_info = api.domain.info(config.get(section, "apikey"),
                                  config.get(section, "domain"))
		current_zone_id = domain_info['zone_id']

		if current_zone_id == 'None':
		  print('No zone - make sure domain is set to use gandi.net name servers.')
		  sys.exit(1)

		zone_id = current_zone_id
	
	return zone_id

def get_zone_ip(config, section):
	"""Get the current IP from the A record in the DNS zone """

	current_zone = api.domain.zone.record.list(config.get(section, "apikey"),
                                             get_zone_id(config, section),
                                             0)
	ip = '0.0.0.0'
	# There may be more than one A record - we're interested in one with 
	# the specific name (typically @ but could be sub domain)
	for d in current_zone:
	  if d['type'] == 'A'and d['name'] == config.get(section, "a_name"):
	    ip = d['value']
	  
	return ip

def get_ip():
	""" Get external IP """
	
	try:
	  # Could be any service that just gives us a simple raw ASCII IP address (not HTML etc)
	  result = urlopen("http://ipv4.myexternalip.com/raw", timeout=3).read()
	except Exception:
	  print('Unable to external IP address.')
	  sys.exit(2);
	
	return result.decode()

def change_zone_ip(config, section, new_ip):
  """ Change the zone record to the new IP """
  a_name = config.get(section, "a_name")
  apikey = config.get(section, "apikey")
  ttl = int(config.get(section, "ttl"))
  zone_id = get_zone_id(config, section)
  
  zone_record ={'name': a_name, 'value': new_ip, 'ttl':ttl, 'type': 'A'}
  
  new_zone_ver = api.domain.zone.version.new(apikey, zone_id)
  
  # clear old A record (defaults to previous verison's
  api.domain.zone.record.delete(apikey, zone_id, new_zone_ver, {'type':'A', 'name': a_name})
  
  # Add in new A record
  api.domain.zone.record.add(apikey, zone_id, new_zone_ver, zone_record)
  
  # Set new zone version as the active zone
  api.domain.zone.version.set(apikey, zone_id, new_zone_ver)

def read_config(config_path):
  """ Open the configuration file or create it if it doesn't exists """
  if not os.path.exists(config_path):
    with open(config_path, "w") as f:
      f.write("""[local]
# gandi.net API (Production) key
apikey = <CHANGE ME>
# Domain
domain = <CHANGE ME>
# A-record name
a_name = @
# TTL (seconds = 5 mintes to 30 days)
ttl = 900
# Production API
api = https://rpc.gandi.net/xmlrpc/
# Host which IP should be changed
host = localhost
""")
    return None
  cfg = configparser.ConfigParser()
  cfg.read(config_path)
  return cfg

def main():
  global api, zone_id
  path = config_file
  if not path.startswith('/'):
    path = os.path.join(SCRIPT_DIR, path)
  config = read_config(path)
  if not config:
    sys.exit("please fill in the 'config.txt' file")

  for section in config.sections():
    api = xmlrpclient.ServerProxy(config.get(section, "api"), verbose=False)

    zone_ip = get_zone_ip(config, section).strip()
    current_ip = socket.gethostbyname(config.get(section, "host"))
    if current_ip == '127.0.0.1':
      current_ip = get_ip()

    if (zone_ip.strip() == current_ip.strip()):
      sys.exit();
    else:
      print('DNS Mistmatch detected: A-record: ', zone_ip, ' WAN IP: ', current_ip)
      change_zone_ip(config, section, current_ip)
      zone_id = None
      zone_ip = get_zone_ip(config, section);
      print('DNS A record update complete - set to ', zone_ip)

if __name__ == "__main__":
  main()