Package dns :: Module reversename
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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 base64 
25   
26  import dns.name 
27  import dns.ipv6 
28  import dns.ipv4 
29   
30  ipv4_reverse_domain = dns.name.from_text('in-addr.arpa.') 
31  ipv6_reverse_domain = dns.name.from_text('ip6.arpa.') 
32   
33 -def from_address(text):
34 """Convert an IPv4 or IPv6 address in textual form into a Name object whose 35 value is the reverse-map domain name of the address. 36 @param text: an IPv4 or IPv6 address in textual form (e.g. '127.0.0.1', 37 '::1') 38 @type text: str 39 @rtype: dns.name.Name object 40 """ 41 try: 42 parts = ['%x.%x' % (byte & 0x0f, byte >> 4) for byte in dns.ipv6.inet_aton(text)] 43 origin = ipv6_reverse_domain 44 except: 45 parts = ['%d' % byte for byte in dns.ipv4.inet_aton(text)] 46 origin = ipv4_reverse_domain 47 parts.reverse() 48 return dns.name.from_text('.'.join(parts).lower(), origin=origin)
49
50 -def to_address(name):
51 """Convert a reverse map domain name into textual address form. 52 @param name: an IPv4 or IPv6 address in reverse-map form. 53 @type name: dns.name.Name object 54 @rtype: str 55 """ 56 if name.is_subdomain(ipv4_reverse_domain): 57 name = name.relativize(ipv4_reverse_domain) 58 labels = list(name.labels) 59 labels.reverse() 60 text = '.'.join([x.decode('ascii') for x in labels]) 61 # run through inet_aton() to check syntax and make pretty. 62 return dns.ipv4.inet_ntoa(dns.ipv4.inet_aton(text)) 63 elif name.is_subdomain(ipv6_reverse_domain): 64 name = name.relativize(ipv6_reverse_domain) 65 labels = list(name.labels) 66 labels.reverse() 67 parts = [] 68 i = 0 69 l = len(labels) 70 while i < l: 71 parts.append(''.join([x.decode('ascii') for x in labels[i:i+4]])) 72 i += 4 73 text = ':'.join(parts) 74 # run through inet_aton() to check syntax and make pretty. 75 return dns.ipv6.inet_ntoa(dns.ipv6.inet_aton(text)) 76 else: 77 raise dns.exception.SyntaxError('unknown reverse-map address family')
78