Source Code for Module dns.reversename

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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