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 system   = fields.getvalue('system')
  38 url      = fields.getvalue('url')
  39
  40
  41 # Base class for our exceptions
  42 class DynDnsError(Exception):
  43         pass
  44
  45 class AuthError(DynDnsError):
  46         returncode = 'badauth'
  47
  48 class UsernameMissing(AuthError):
  49         pass
  50
  51 class UsernameInvalid(AuthError):
  52         pass
  53
  54 class PasswordMissing(AuthError):
  55         pass
  56
  57 class PasswordWrong(AuthError):
  58         pass
  59
  60 class HostnameError(DynDnsError):
  61         returncode = 'notfqdn'
  62
  63 class HostnameMissing(HostnameError):
  64         pass
  65
  66 class PasswordWrong(HostnameError):
  67         pass
  68
  69 class IpError(DynDnsError):
  70         returncode = 'badip' # not documented at dyn.com
  71
  72 class IpMissing(IpError):
  73         pass
  74
  75 class IpInvalid(IpError):
  76         pass
  77
  78 try:
  79         # check username
  80         if username is None:
  81                 raise UsernameMissing()
  82         try:
  83                 user_info = pwd.getpwnam(username)
  84         except KeyError:
  85                 raise UsernameInvalid()
  86         if user_info.pw_uid < 1000:
  87                 raise UsernameInvalid()
  88
  89         # check password
  90         if password is None:
  91                 raise PasswordMissing()
  92         if password != PASSWORD:
  93                 raise PasswordWrong()
  94
  95         # check hostname
  96         if hostname is None:
  97                 raise HostnameMissing()
  98         if re.match(r'[-0-9a-z]+(\.[-0-9a-z]+)*$', hostname) is None:
  99                 raise HostnameInvalid()
 100
 101         # strip zone
 102         hostname = hostname.strip()
 103         if hostname.endswith(ZONE):
 104                 hostname = hostname[:-len(ZONE)]
 105
 106         # check IP address
 107         if myip is None:
 108                 raise IpMissing()
 109         try:
 110                 ip = ipaddr.IPAddress(myip) # throws an exception if the IP address is not valid
 111         except ValueError:
 112                 raise IpInvalid()
 113         if isinstance(ip, ipaddr.IPv4Address):
 114                 iptype = 'A'
 115         elif isinstance(ip, ipaddr.IPv6Address):
 116                 iptype = 'AAAA'
 117         else:
 118                 raise IpInvalid() # should never happen
 119
 120         # access granted
 121         print "Content-Type: text/html"
 122         print
 123         call(['sudo', '/usr/local/bin/nsupdate_dyndns', hostname, myip, iptype])
 124         print "good"
 125         # Note: we should return 'nochg' in case the IP has not changed, however we don't know yet.
 126
 127
 128 except DynDnsError as error:
 129         print "Content-Type: text/html"
 130         print "Status: 200"
 131         print
 132         print error.returncode
 133