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
  16
  17 # Just for debugging:
  18 # import cgitb
  19 # cgitb.enable()
  20
  21
  22 fields = cgi.FieldStorage()
  23
  24 username = fields.getvalue('username')
  25 password = fields.getvalue('password')
  26 hostname = fields.getvalue('hostname')
  27 myip     = fields.getvalue('myip')
  28
  29 # Strip zone
  30 hostname = re.sub('\.dyn\.colgarra\.priv\.at\s*$', '', hostname)
  31
  32 try:
  33         # check username
  34         user_info = pwd.getpwnam(username) # returns a key error if the user does not exist
  35         if user_info.pw_uid < 1000:
  36                 raise RuntimeError('Invalid user name')
  37
  38         # check password
  39         if password != PASSWORD:
  40                 raise RuntimeError('Invalid password')
  41
  42         # check hostname
  43         if re.match(r'[-0-9a-z]+(\.[-0-9a-z]+)*$', hostname) is None:
  44                 raise RuntimeError('Invalid host name')
  45
  46         # check IP address
  47         ip = ipaddr.IPAddress(myip) # throws axception if the IP address is not valid
  48         if isinstance(ip, ipaddr.IPv4Address):
  49                 type = 'A'
  50         elif isinstance(ip, ipaddr.IPv6Address):
  51                 type = 'AAAA'
  52         else:
  53                 raise RuntimeError('Unknown IP address type')
  54
  55         # access granted
  56         print "Content-Type: text/html"
  57         print
  58         call(['sudo', '/usr/local/bin/nsupdate_dyndns', hostname, myip, type])
  59         print "OK"
  60
  61
  62 except:
  63         # access denied
  64         print "Content-Type: text/html"
  65         print "Status: 403 Forbidden"
  66         print
  67         print "Denied"
  68