bin/tdyndns_update

   1 #!/usr/bin/python
   2 import os
   3 import sys
   4 import re
   5 import argparse
   6 from subprocess import Popen, PIPE, check_call, CalledProcessError
   7 import ipaddr
   8 import dns.zone  # http://www.dnspython.org/
   9
  10
  11 def sync_dynamic_zones():
  12         check_call(['rndc', 'sync'])
  13
  14
  15 def ipfamily_by_ip(ip):
  16         if isinstance(ip, ipaddr.IPv4Address):
  17                 return 'A'
  18         elif isinstance(ip, ipaddr.IPv6Address):
  19                 return 'AAAA'
  20         assert False
  21
  22
  23 def forward_lookup(fqdn, ip_family):
  24         """Returns the ip address of the fqdn or None if none is found..
  25
  26         :param fqdn: Fully qualified domain name.
  27         :param ip_family: 'A' or 'AAAA'"""
  28         filename = '/var/cache/bind/dyn.colgarra.priv.at'
  29         zonename = os.path.basename(filename)
  30         zone = dns.zone.from_file(filename, zonename, relativize=False)
  31         for name, ttl, rdata in zone.iterate_rdatas(ip_family):
  32                 if str(name)[:-1] == fqdn:  # [:-1] removes trailing dot
  33                         return ipaddr.IPAddress(rdata.address)
  34
  35
  36 def reverse_lookup(ip):
  37         """Returns an iterator of fqdns for the given IP address.
  38
  39         :param ip: Instance of ipaddr.IPv4Address or ipaddr.IPv6Address"""
  40         filename = '/var/cache/bind/dyn.colgarra.priv.at'
  41         zonename = os.path.basename(filename)
  42         zone = dns.zone.from_file(filename, zonename, relativize=False)
  43         for name, ttl, rdata in zone.iterate_rdatas(ipfamily_by_ip(ip)):
  44                 if ipaddr.IPAddress(rdata.address) == ip:
  45                         yield str(name)
  46
  47
  48 def nsupdate_add(fqdn, ttl, ip):
  49         """
  50         :param fqdn: Fully qualified domain name
  51         :param ip_family: A or AAAA
  52         :raises an CalledProcessError in case of errors."""
  53         command = "update add {fqdn} {ttl} IN {ip_family} {ip}\n\n".format(fqdn=fqdn, ttl=ttl, ip_family=ipfamily_by_ip(ip), ip=ip)
  54         p = Popen(['nsupdate', '-l'], stdin=PIPE)
  55         p.communicate(command)
  56         if p.returncode != 0:
  57                 raise CalledProcessError(p.returncode, 'nsupdate -l')
  58
  59 def nsupdate_delete(fqdn, ip_family):
  60         """
  61         :param fqdn: Fully qualified domain name
  62         :param ip_family: A or AAAA
  63         :raises an CalledProcessError in case of errors."""
  64         command = "update delete {fqdn} {ip_family}\n\n".format(fqdn=fqdn, ip_family=ip_family)
  65         p = Popen(['nsupdate', '-l'], stdin=PIPE)
  66         p.communicate(command)
  67         if p.returncode != 0:
  68                 raise CalledProcessError(p.returncode, 'nsupdate -l')
  69
  70
  71 def blockip_whitelist_add(ip):
  72         """
  73         :param ip: ipv4 address
  74         """
  75         if ipfamily_by_ip(ip) == 'A':
  76                 command = ['iptables', '-I', 'blockip', '-s', str(ip), '-j', 'ACCEPT']
  77                 p = Popen(command, stderr=PIPE)
  78                 stdout, stderr = p.communicate()
  79
  80
  81 def blockip_whitelist_delete(ip):
  82         """
  83         :param ip: ipv4 address
  84         """
  85         if ipfamily_by_ip(ip) == 'A':
  86                 command = ['iptables', '-D', 'blockip', '-s', str(ip), '-j', 'ACCEPT']
  87                 p = Popen(command, stderr=PIPE)
  88                 stdout, stderr = p.communicate()
  89
  90
  91 def main(args):
  92         try:
  93                 if args.delete:
  94                         if args.ip is None:
  95                                 nsupdate_delete(args.fqdn, 'A')
  96                                 nsupdate_delete(args.fqdn, 'AAAA')
  97                         else:
  98                                 ipfamily = ipfamily_by_ip(args.ip)
  99                                 sync_dynamic_zones()
 100                                 old_ip = forward_lookup(args.fqdn, ipfamily)
 101                                 nsupdate_delete(args.fqdn, ipfamily_by_ip(args.ip))
 102                                 if old_ip is not None:
 103                                         blockip_whitelist_delete(old_ip)
 104                 else:
 105                         ipfamily = ipfamily_by_ip(args.ip)
 106                         sync_dynamic_zones()
 107                         old_ip = forward_lookup(args.fqdn, ipfamily)
 108                         nsupdate_delete(args.fqdn, ipfamily)
 109                         nsupdate_add(args.fqdn, args.ttl, args.ip)
 110                         if old_ip != args.ip:
 111                                 if old_ip is not None:
 112                                         blockip_whitelist_delete(old_ip)
 113                                 blockip_whitelist_add(args.ip)
 114         except CalledProcessError as e:
 115                 sys.exit(e.returncode)
 116
 117
 118
 119 if __name__ == '__main__':
 120         parser = argparse.ArgumentParser(description='Add or delete a domain name from dyndns (simplifies call to nsupdate).')
 121         parser.add_argument('-d', '--delete', action='store_true', help='delete instead of add')
 122         parser.add_argument('-i', '--ip', help='IP address (either IPv4 or IPv6)')
 123         parser.add_argument('-t', '--ttl', type=int, default=600, help='TTL (default: 600)')
 124         parser.add_argument('fqdn', help='fully qualified domain name to add or delete, e.g. myserver.dyn.example.com')
 125         args = parser.parse_args()
 126
 127         # check ip
 128         if not args.delete and not args.ip:
 129                 parser.error('The IP address is mandatory')
 130         if args.ip:
 131                 try:
 132                         args.ip = ipaddr.IPAddress(args.ip) # throws an exception if the IP address is not valid
 133                 except ValueError:
 134                         parser.error('The IP address is not valid')
 135
 136         # check fqdn
 137         if re.match(r'[-0-9a-z]+(\.[-0-9a-z]+)*$', args.fqdn) is None:
 138                 parser.error('The fqdn has an invalid format.')
 139
 140         main(args)