dyngo

   1 #!/usr/bin/env python3
   2 import ipaddress, subprocess, sys, getopt,dbm
   3 from configparser import ConfigParser
   4 import urllib.request,urllib.parse
   5 import logging,os.path,time
   6 class DyndnsNetwork(object):
   7     """
   8     This class represents dynamic DNS server and network.
   9     It has attributes hostname network server user and password
  10     """
  11     def __init__(self,config_section):
  12         self.hostname = config_section['hostname']
  13         self.network = ipaddress.ip_network(config_section['network'])
  14         self.server = config_section['server']
  15         if 'user' in config_section:
  16             self.user=config_section["user"]
  17             self.password=config_section["password"]
  18
  19
  20     def contains(self,address):
  21         if self.network.prefixlen==0 and address.is_private:
  22             return False
  23         if self.network.version != address.version:
  24             return False
  25         return address in self.network
  26     def nsupdate(self, address):
  27         """
  28         Sends a get query to specified server.
  29         Raises HTTPError if something goes wrong
  30         """
  31         #construct opener
  32         logging.debug("Going to send message to %s",self.server)
  33         if hasattr(self,'user'):
  34             password_mgr =urllib.request.HTTPPasswordMgrWithDefaultRealm()
  35             password_mgr.add_password(None,self.server,self.user,self.password)
  36             handler=urllib.request.HTTPBasicAuthHandler(password_mgr)
  37             opener = urllib.request.build_opener(handler)
  38         else:
  39             opener = urllib.request.build_opener()
  40         with opener.open('%s?%s'%(self.server,
  41                      urllib.parse.urlencode({'hostname':self.hostname,
  42                      'myip':str(address)}))) as req:
  43                req.read().decode("utf-8")
  44
  45
  46
  47 def get_current_addresses():
  48     result=[]
  49     logging.debug("Acquire current IPs")
  50     for line in subprocess.run(['ip','-o','addr','show'],check=True,stdout=subprocess.PIPE).stdout.decode('utf-8').split("\n"):
  51         if not len(line):
  52             continue
  53         (no,iface,family,addr,rest)=line.split(maxsplit=4)
  54         address=ipaddress.ip_address(addr.split('/')[0])
  55         if address.is_loopback or address.is_link_local:
  56             continue
  57         result.append(address)
  58     logging.debug("Got following addresses: %s",repr(result))
  59     return result
  60 def check_for_update():
  61     addrlist=get_current_addresses()
  62     for name,net in networks.items():
  63         found=False
  64         for a in addrlist:
  65             if net.contains(a):
  66                 found =True
  67                 if name in database:
  68                     old_addr=ipaddress.ip_address(database[name].decode("utf-8"))
  69                     if old_addr==a:
  70                         # Nothing changed go, to next net
  71                         logging.debug("Address for net %s not changed",name)
  72                         break
  73                 # address changed
  74                 try:
  75                      logging.info("Doing update for net %s with address %s",name, str(a))
  76                      net.nsupdate(a)
  77                      database[name]=str(a)
  78                 except urllib.error.HTTPError as e:
  79                     logging.exception("Http error doing nsupdate code %s",e.code)
  80                 break
  81         if not found:
  82             logging.info("Address for net %s no more found",name)
  83             if name in database:
  84                 del database[name]
  85
  86 config=ConfigParser()
  87 config['dyngo']={'interval':'60','database':'/var/lib/dyngo/dyngo.db',
  88                  'ca':'/etc/ssl/certs','loglevel':'WARNING'}
  89 options=dict(getopt.getopt(sys.argv,"f:")[0])
  90 if not '-f' in options:
  91     options["-f"]="/etc/dyngo.conf"
  92 if len(config.read(options["-f"]))!=1:
  93     print("Cannot read config %s"%options["-f"],file=sys.stderr)
  94     sys.exit(1)
  95 conf=config['dyngo']
  96 if conf['loglevel'].isdigit():
  97     level=int(conf['loglevel'])
  98 else:
  99     try:
 100         logging.NOTICE=25
 101         level=getattr(logging,conf['loglevel'].upper())
 102     except AttributeError:
 103         print("Invalid logleevel '%s'"%conf('loglevel'))
 104         sys.exit(1)
 105
 106 logging.basicConfig(format="%(asctime)s %(message)s",
 107       level=level, stream=sys.stderr)
 108 interval=int(conf['interval'])
 109 database=dbm.open(conf['database'],"c")
 110 https_params={}
 111 if 'ca' in conf and len(conf['ca']):
 112     path=conf['ca']
 113     if os.path.isdir(path):
 114         https_params['capath']=path
 115     else:
 116         http_params['cafile']=path
 117 # Convert all other config sections to DyndnsNetwork objects
 118 networks={}
 119 for sect in config.sections():
 120     if sect == 'dyngo' or sect == 'DEFAULT':
 121         continue
 122     logging.debug("Processing network %s",sect)
 123     networks[sect]=DyndnsNetwork(config[sect])
 124 # Remove stale items from persistent database, which are no more
 125 # mentioned in the config file
 126 for i in set([x.decode("utf-8") for x in database.keys()])-set(networks.keys()):
 127     logging.info("Removing from persistent state network %s which is no more  in config",i)
 128     del database[i]
 129
 130 while True:
 131     check_for_update()
 132     time.sleep(interval)
 133