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

     1  # Copyright (C) 2006, 2007, 2009-2011 Nominum, Inc.
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     4  # documentation for any purpose with or without fee is hereby granted,
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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          v6 = dns.ipv6.inet_aton(text)
    41          if dns.ipv6.is_mapped(v6):
    42              parts = ['%d' % ord(byte) for byte in v6[12:]]
    43              origin = ipv4_reverse_domain
    44          else:
    45              parts = list(v6.encode('hex_codec'))
    46              origin = ipv6_reverse_domain
    47      except:
    48          parts = ['%d' % ord(byte) for byte in dns.ipv4.inet_aton(text)]
    49          origin = ipv4_reverse_domain
    50      parts.reverse()
    51      return dns.name.from_text('.'.join(parts), origin=origin)
    52
    53 -def to_address(name):
    54      """Convert a reverse map domain name into textual address form.
    55      @param name: an IPv4 or IPv6 address in reverse-map form.
    56      @type name: dns.name.Name object
    57      @rtype: str
    58      """
    59      if name.is_subdomain(ipv4_reverse_domain):
    60          name = name.relativize(ipv4_reverse_domain)
    61          labels = list(name.labels)
    62          labels.reverse()
    63          text = '.'.join(labels)
    64          # run through inet_aton() to check syntax and make pretty.
    65          return dns.ipv4.inet_ntoa(dns.ipv4.inet_aton(text))
    66      elif name.is_subdomain(ipv6_reverse_domain):
    67          name = name.relativize(ipv6_reverse_domain)
    68          labels = list(name.labels)
    69          labels.reverse()
    70          parts = []
    71          i = 0
    72          l = len(labels)
    73          while i < l:
    74              parts.append(''.join(labels[i:i+4]))
    75              i += 4
    76          text = ':'.join(parts)
    77          # run through inet_aton() to check syntax and make pretty.
    78          return dns.ipv6.inet_ntoa(dns.ipv6.inet_aton(text))
    79      else:
    80          raise dns.exception.SyntaxError('unknown reverse-map address family')
    81