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 DEBUG = False
  17
  18
  19 # Just for debugging:
  20 if DEBUG:
  21         import cgitb
  22         cgitb.enable()
  23
  24
  25 fields = cgi.FieldStorage()
  26
  27 # the following fields are supported by most dyndns providers
  28 # if a parameter is not provided, the .getvalue method returns None
  29 username = fields.getvalue('username')
  30 password = fields.getvalue('password')
  31 hostname = fields.getvalue('hostname')
  32 myip     = fields.getvalue('myip')
  33 wildcard = fields.getvalue('wildcard')
  34 mx       = fields.getvalue('mx')
  35 backmx   = fields.getvalue('backmx')
  36 offline  = fields.getvalue('offline')
  37
  38
  39 try:
  40         # check username
  41         user_info = pwd.getpwnam(username) # returns a key error if the user does not exist
  42         if user_info.pw_uid < 1000:
  43                 raise RuntimeError('Invalid user name')
  44
  45         # check password
  46         if password != PASSWORD:
  47                 raise RuntimeError('Invalid password')
  48
  49         # check hostname
  50         if re.match(r'[-0-9a-z]+(\.[-0-9a-z]+)*$', hostname) is None:
  51                 raise RuntimeError('Invalid host name')
  52
  53         # strip zone
  54         hostname = hostname.strip()
  55         if hostname.endswith(ZONE):
  56                 hostname = hostname[:-len(ZONE)]
  57
  58         # check IP address
  59         ip = ipaddr.IPAddress(myip) # throws axception if the IP address is not valid
  60         if isinstance(ip, ipaddr.IPv4Address):
  61                 type = 'A'
  62         elif isinstance(ip, ipaddr.IPv6Address):
  63                 type = 'AAAA'
  64         else:
  65                 raise RuntimeError('Unknown IP address type')
  66
  67         # access granted
  68         print "Content-Type: text/html"
  69         print
  70         call(['sudo', '/usr/local/bin/nsupdate_dyndns', hostname, myip, type])
  71         print "OK"
  72
  73
  74 except:
  75         # access denied
  76         print "Content-Type: text/html"
  77         print "Status: 403 Forbidden"
  78         print
  79         print "Denied"
  80