we now track blockip and only add when needed and only delete entries we created.

[toast/tdyndns.git] / bin / tdyndns_update

diff --git a/bin/tdyndns_update b/bin/tdyndns_update
index 45c42640bc9a0bf9e8b6c332a4f6359fb42c9903..0667c87019e9c5346dd96ef8b733d158bf902441 100755 (executable)
--- a/bin/tdyndns_update
+++ b/bin/tdyndns_update
@@ -1,23 +1,15 @@
 #!/usr/bin/python
+import os
 import sys
 import re
 import argparse
-from subprocess import Popen, PIPE, call
+from subprocess import Popen, PIPE, check_call, CalledProcessError
 import ipaddr
+import dns.zone  # http://www.dnspython.org/
 
 
-class ExternalProgramError(RuntimeError):
-       pass
-
-
-class NsupdateError(ExternalProgramError):
-       def __init__(self, returncode):
-               self.returncode = returncode
-
-
-class BlockipError(ExternalProgramError):
-       def __init__(self, returncode):
-               self.returncode = returncode
+def sync_dynamic_zones():
+       check_call(['rndc', 'sync'])
 
 
 def ipfamily_by_ip(ip):
@@ -28,6 +20,31 @@ def ipfamily_by_ip(ip):
        assert False
 
 
+def forward_lookup(fqdn, ip_family):
+       """Returns the ip address of the fqdn or None if none is found..
+
+       :param fqdn: Fully qualified domain name.
+       :param ip_family: 'A' or 'AAAA'"""
+       filename = '/var/cache/bind/dyn.colgarra.priv.at'
+       zonename = os.path.basename(filename)
+       zone = dns.zone.from_file(filename, zonename, relativize=False)
+       for name, ttl, rdata in zone.iterate_rdatas(ip_family):
+               if str(name)[:-1] == fqdn:  # [:-1] removes trailing dot
+                       return ipaddr.IPAddress(rdata.address)
+
+
+def reverse_lookup(ip):
+       """Returns an iterator of fqdns for the given IP address.
+
+       :param ip: Instance of ipaddr.IPv4Address or ipaddr.IPv6Address"""
+       filename = '/var/cache/bind/dyn.colgarra.priv.at'
+       zonename = os.path.basename(filename)
+       zone = dns.zone.from_file(filename, zonename, relativize=False)
+       for name, ttl, rdata in zone.iterate_rdatas(ipfamily_by_ip(ip)):
+               if ipaddr.IPAddress(rdata.address) == ip:
+                       yield str(name)
+
+
 def nsupdate_add(fqdn, ttl, ip):
        """
        :param fqdn: Fully qualified domain name
@@ -37,7 +54,7 @@ def nsupdate_add(fqdn, ttl, ip):
        p = Popen(['nsupdate', '-l'], stdin=PIPE)
        p.communicate(command)
        if p.returncode != 0:
-               raise NsupdateError(p.returncode)
+               raise CalledProcessError(p.returncode, 'nsupdate -l')
 
 def nsupdate_delete(fqdn, ip_family):
        """
@@ -48,27 +65,25 @@ def nsupdate_delete(fqdn, ip_family):
        p = Popen(['nsupdate', '-l'], stdin=PIPE)
        p.communicate(command)
        if p.returncode != 0:
-               raise NsupdateError(p.returncode)
+               raise CalledProcessError(p.returncode, 'nsupdate -l')
 
 
 def blockip_whitelist_add(ip):
        """
        :param ip: ipv4 address
        :raises a BlockipError in case of errors."""
-       command = ['iptables', '-I', 'blockip', '-s', str(ip), '-j', 'ACCEPT']
-       p = call(command)
-       if p != 0:
-               raise BlockipError(p)
+       if ipfamily_by_ip(ip) == 'A':
+               command = ['iptables', '-I', 'blockip', '-s', str(ip), '-j', 'ACCEPT']
+               check_call(command)
 
 
 def blockip_whitelist_delete(ip):
        """
        :param ip: ipv4 address
        :raises a BlockipError in case of errors."""
-       command = ['iptables', '-D', 'blockip', '-s', str(ip), '-j', 'ACCEPT']
-       p = call(command)
-       if p != 0:
-               raise BlockipError(p)
+       if ipfamily_by_ip(ip) == 'A':
+               command = ['iptables', '-D', 'blockip', '-s', str(ip), '-j', 'ACCEPT']
+               check_call(command)
 
 
 def main(args):
@@ -78,15 +93,23 @@ def main(args):
                                nsupdate_delete(args.fqdn, 'A')
                                nsupdate_delete(args.fqdn, 'AAAA')
                        else:
+                               ipfamily = ipfamily_by_ip(args.ip)
+                               sync_dynamic_zones()
+                               old_ip = forward_lookup(args.fqdn, ipfamily)
                                nsupdate_delete(args.fqdn, ipfamily_by_ip(args.ip))
-                               if ipfamily_by_ip(args.ip) == 'A':
-                                       blockip_whitelist_delete(args.ip)
+                               if old_ip is not None:
+                                       blockip_whitelist_delete(old_ip)
                else:
-                       nsupdate_delete(args.fqdn, ipfamily_by_ip(args.ip))
+                       ipfamily = ipfamily_by_ip(args.ip)
+                       sync_dynamic_zones()
+                       old_ip = forward_lookup(args.fqdn, ipfamily)
+                       nsupdate_delete(args.fqdn, ipfamily)
                        nsupdate_add(args.fqdn, args.ttl, args.ip)
-                       if ipfamily_by_ip(args.ip) == 'A':
+                       if old_ip != args.ip:
+                               if old_ip is not None:
+                                       blockip_whitelist_delete(old_ip)
                                blockip_whitelist_add(args.ip)
-       except ExternalProgramError as e:
+       except CalledProcessError as e:
                sys.exit(e.returncode)