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 username = fields.getvalue('username')
  26 password = fields.getvalue('password')
  27 hostname = fields.getvalue('hostname')
  28 myip     = fields.getvalue('myip')
  29
  30 # Strip zone
  31 hostname = hostname.strip()
  32 if hostname.endswith(ZONE):
  33         hostname = hostname[:-len(ZONE)]
  34
  35 try:
  36         # check username
  37         user_info = pwd.getpwnam(username) # returns a key error if the user does not exist
  38         if user_info.pw_uid < 1000:
  39                 raise RuntimeError('Invalid user name')
  40
  41         # check password
  42         if password != PASSWORD:
  43                 raise RuntimeError('Invalid password')
  44
  45         # check hostname
  46         if re.match(r'[-0-9a-z]+(\.[-0-9a-z]+)*$', hostname) is None:
  47                 raise RuntimeError('Invalid host name')
  48
  49         # check IP address
  50         ip = ipaddr.IPAddress(myip) # throws axception if the IP address is not valid
  51         if isinstance(ip, ipaddr.IPv4Address):
  52                 type = 'A'
  53         elif isinstance(ip, ipaddr.IPv6Address):
  54                 type = 'AAAA'
  55         else:
  56                 raise RuntimeError('Unknown IP address type')
  57
  58         # access granted
  59         print "Content-Type: text/html"
  60         print
  61         call(['sudo', '/usr/local/bin/nsupdate_dyndns', hostname, myip, type])
  62         print "OK"
  63
  64
  65 except:
  66         # access denied
  67         print "Content-Type: text/html"
  68         print "Status: 403 Forbidden"
  69         print
  70         print "Denied"
  71