dyngo

   1 #!/usr/bin/env python3
   2 import ipaddress, subprocess, sys, getopt,dbm
   3 from configparser import ConfigParser
   4 class DyndnsNetwork(object):
   5     """
   6     This class represents dynamic DNS server and network.
   7     It has attributes hostname network server user and password
   8     """
   9     def __init__(self,config_section):
  10         self.hostname = config_section['hostname']
  11         self.network = ipaddress.ip_network(config_section['network'])
  12         self.server = config_section['server']
  13         if user in config_section:
  14             self.user=config_section["user"]
  15             self.password=config_section["password"]
  16
  17
  18     def contains(self,address):
  19         if self.network.prefixlen==0 and address.is_private:
  20             return False
  21         if self.network.version != address.version:
  22             return False
  23         return address in self.network
  24    def nsupdate(self, address):
  25         raise NotImplementedError
  26
  27 def get_current_addresses():
  28     result=[]
  29     for line in subprocess.run(['ip','-o','addr','show'],check=True,stdout=subprocess.PIPE).stdout.decode('utf-8').split("\n"):
  30         if not len(line):
  31             continue
  32         (no,iface,family,addr,rest)=line.split(maxsplit=4)
  33         address=ipaddress.ip_address(addr.split('/')[0])
  34         if address.is_loopback or address.is_link_local:
  35             continue
  36         result.append(address)
  37     return result
  38 def check_for_update():
  39     addrlist=get_current_addresses()
  40     for name,net in networks.items():
  41         found=False
  42         for a in addrlist:
  43             if net.contains(a):
  44                 found =True
  45                 if name in database:
  46                     old_addr=ipaddress.ip_address(database[name].decode("utf-8"))
  47                     if old_addr==a:
  48                         # Nothing changed go, to next net
  49                         break
  50                 # address changed
  51                 net.nsupdate(a)
  52                 database[name]=str(a)
  53         if not found:
  54             del data[name]
  55
  56
  57
  58
  59 config=ConfigPaser()
  60 config['dyngo']={'interval':'60','database','/var/lib/dyngo/dyngo.db'}
  61 options=dict(getopt.getopt(sys.argv,"f:")[0])
  62 if not '-f' in options:
  63     options["-f"]="/etc/dyngo.conf"
  64 if len(config.read(options["-f"]))!=1:
  65     print("Cannot read config %s"%options["-f"],file=sys.stderr)
  66     sys.exit(1)
  67
  68 conf=config['dyngo']
  69 interval=int(conf['interval'])
  70 database=dbm.open(conf['database'],"c")
  71 # Convert all other config sections to DyndnsNetwork objects
  72 networks={}
  73 for sect in config.sections():
  74     if sect == 'dyngo' or sect= 'DEFAULT':
  75         continue
  76     networks[sect]=DyndnsNetwork(config[sect])
  77 # Remove stale items from persistent database, which are no more
  78 # mentioned in the config file
  79 for i in set([x.decode("utf-8") for x database.keys()])-set(network.keys()):
  80     del database[i]
  81
  82
  83 while True:
  84     check_for_update()
  85     time.sleep(interval)
  86