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      1 # Copyright (C) 2006, 2007, 2009, 2010 Nominum, Inc.
      2 #
      3 # Permission to use, copy, modify, and distribute this software and its
      4 # documentation for any purpose with or without fee is hereby granted,
      5 # provided that the above copyright notice and this permission notice
      6 # appear in all copies.
      7 #
      8 # THE SOFTWARE IS PROVIDED "AS IS" AND NOMINUM DISCLAIMS ALL WARRANTIES
      9 # WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
     10 # MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL NOMINUM BE LIABLE FOR
     11 # ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
     12 # WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
     13 # ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
     14 # OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
     15 
     16 """DNS Reverse Map Names.
     17 
     18 @var ipv4_reverse_domain: The DNS IPv4 reverse-map domain, in-addr.arpa.
     19 @type ipv4_reverse_domain: dns.name.Name object
     20 @var ipv6_reverse_domain: The DNS IPv6 reverse-map domain, ip6.arpa.
     21 @type ipv6_reverse_domain: dns.name.Name object
     22 """
     23 
     24 import dns.name
     25 import dns.ipv6
     26 import dns.ipv4
     27 
     28 ipv4_reverse_domain = dns.name.from_text('in-addr.arpa.')
     29 ipv6_reverse_domain = dns.name.from_text('ip6.arpa.')
     30 
     31 def from_address(text):
     32     """Convert an IPv4 or IPv6 address in textual form into a Name object whose
     33     value is the reverse-map domain name of the address.
     34     @param text: an IPv4 or IPv6 address in textual form (e.g. '127.0.0.1',
     35     '::1')
     36     @type text: str
     37     @rtype: dns.name.Name object
     38     """
     39     try:
     40         parts = list(dns.ipv6.inet_aton(text).encode('hex_codec'))
     41         origin = ipv6_reverse_domain
     42     except:
     43         parts = ['%d' % ord(byte) for byte in dns.ipv4.inet_aton(text)]
     44         origin = ipv4_reverse_domain
     45     parts.reverse()
     46     return dns.name.from_text('.'.join(parts), origin=origin)
     47 
     48 def to_address(name):
     49     """Convert a reverse map domain name into textual address form.
     50     @param name: an IPv4 or IPv6 address in reverse-map form.
     51     @type name: dns.name.Name object
     52     @rtype: str
     53     """
     54     if name.is_subdomain(ipv4_reverse_domain):
     55         name = name.relativize(ipv4_reverse_domain)
     56         labels = list(name.labels)
     57         labels.reverse()
     58         text = '.'.join(labels)
     59         # run through inet_aton() to check syntax and make pretty.
     60         return dns.ipv4.inet_ntoa(dns.ipv4.inet_aton(text))
     61     elif name.is_subdomain(ipv6_reverse_domain):
     62         name = name.relativize(ipv6_reverse_domain)
     63         labels = list(name.labels)
     64         labels.reverse()
     65         parts = []
     66         i = 0
     67         l = len(labels)
     68         while i < l:
     69             parts.append(''.join(labels[i:i+4]))
     70             i += 4
     71         text = ':'.join(parts)
     72         # run through inet_aton() to check syntax and make pretty.
     73         return dns.ipv6.inet_ntoa(dns.ipv6.inet_aton(text))
     74     else:
     75         raise dns.exception.SyntaxError('unknown reverse-map address family')
     76