lib/dnspython/dns/reversename.py

   1 # Copyright (C) 2006, 2007, 2009-2011 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')