Package dns :: Module reversename |
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# Source Code for Module dns.reversename

     1  # Copyright (C) 2006, 2007, 2009, 2010 Nominum, Inc.
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     8  # THE SOFTWARE IS PROVIDED "AS IS" AND NOMINUM DISCLAIMS ALL WARRANTIES
     9  # WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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    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