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("https://api.ipify.org", 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)


default_config = """[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
"""


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(default_config)
        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()