cgi-bin/dyndns.py

   1 #!/usr/bin/python2.7
   2 """Dynamic DNS script. Expects URLs from routers in the form
   3 https://info.colgarra.priv.at/dyndns/dyndns.py?username=<username>&password=<pass>&hostname=<domain>&myip=<ipaddr>
   4 """
   5
   6 import re
   7 import cgi
   8 import pwd
   9 from subprocess import call
  10 import ipaddr
  11
  12
  13 # Configuration
  14 PASSWORD = 'hygCithOrs5'
  15 ZONE = '.dyn.colgarra.priv.at'
  16
  17
  18 # Just for debugging:
  19 # import cgitb
  20 # cgitb.enable()
  21
  22
  23 fields = cgi.FieldStorage()
  24
  25 # the following fields are supported by most dyndns providers
  26 # if a parameter is not provided, the .getvalue method returns None
  27 username = fields.getvalue('username')
  28 password = fields.getvalue('password')
  29 hostname = fields.getvalue('hostname')
  30 myip     = fields.getvalue('myip')
  31 wildcard = fields.getvalue('wildcard')
  32 mx       = fields.getvalue('mx')
  33 backmx   = fields.getvalue('backmx')
  34 offline  = fields.getvalue('offline')
  35
  36
  37 try:
  38         # check username
  39         user_info = pwd.getpwnam(username) # returns a key error if the user does not exist
  40         if user_info.pw_uid < 1000:
  41                 raise RuntimeError('Invalid user name')
  42
  43         # check password
  44         if password != PASSWORD:
  45                 raise RuntimeError('Invalid password')
  46
  47         # check hostname
  48         if re.match(r'[-0-9a-z]+(\.[-0-9a-z]+)*$', hostname) is None:
  49                 raise RuntimeError('Invalid host name')
  50
  51         # strip zone
  52         hostname = hostname.strip()
  53         if hostname.endswith(ZONE):
  54                 hostname = hostname[:-len(ZONE)]
  55
  56         # check IP address
  57         ip = ipaddr.IPAddress(myip) # throws axception if the IP address is not valid
  58         if isinstance(ip, ipaddr.IPv4Address):
  59                 type = 'A'
  60         elif isinstance(ip, ipaddr.IPv6Address):
  61                 type = 'AAAA'
  62         else:
  63                 raise RuntimeError('Unknown IP address type')
  64
  65         # access granted
  66         print "Content-Type: text/html"
  67         print
  68         call(['sudo', '/usr/local/bin/nsupdate_dyndns', hostname, myip, type])
  69         print "OK"
  70
  71
  72 except:
  73         # access denied
  74         print "Content-Type: text/html"
  75         print "Status: 403 Forbidden"
  76         print
  77         print "Denied"
  78