lib/dnspython/dns/inet.py

   1 # Copyright (C) 2003-2007, 2009-2011 Nominum, Inc.
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  14 # OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  15
  16 """Generic Internet address helper functions."""
  17
  18 import socket
  19
  20 import dns.ipv4
  21 import dns.ipv6
  22
  23
  24 # We assume that AF_INET is always defined.
  25
  26 AF_INET = socket.AF_INET
  27
  28 # AF_INET6 might not be defined in the socket module, but we need it.
  29 # We'll try to use the socket module's value, and if it doesn't work,
  30 # we'll use our own value.
  31
  32 try:
  33     AF_INET6 = socket.AF_INET6
  34 except AttributeError:
  35     AF_INET6 = 9999
  36
  37 def inet_pton(family, text):
  38     """Convert the textual form of a network address into its binary form.
  39
  40     @param family: the address family
  41     @type family: int
  42     @param text: the textual address
  43     @type text: string
  44     @raises NotImplementedError: the address family specified is not
  45     implemented.
  46     @rtype: string
  47     """
  48
  49     if family == AF_INET:
  50         return dns.ipv4.inet_aton(text)
  51     elif family == AF_INET6:
  52         return dns.ipv6.inet_aton(text)
  53     else:
  54         raise NotImplementedError
  55
  56 def inet_ntop(family, address):
  57     """Convert the binary form of a network address into its textual form.
  58
  59     @param family: the address family
  60     @type family: int
  61     @param address: the binary address
  62     @type address: string
  63     @raises NotImplementedError: the address family specified is not
  64     implemented.
  65     @rtype: string
  66     """
  67     if family == AF_INET:
  68         return dns.ipv4.inet_ntoa(address)
  69     elif family == AF_INET6:
  70         return dns.ipv6.inet_ntoa(address)
  71     else:
  72         raise NotImplementedError
  73
  74 def af_for_address(text):
  75     """Determine the address family of a textual-form network address.
  76
  77     @param text: the textual address
  78     @type text: string
  79     @raises ValueError: the address family cannot be determined from the input.
  80     @rtype: int
  81     """
  82     try:
  83         junk = dns.ipv4.inet_aton(text)
  84         return AF_INET
  85     except:
  86         try:
  87             junk = dns.ipv6.inet_aton(text)
  88             return AF_INET6
  89         except:
  90             raise ValueError
  91
  92 def is_multicast(text):
  93     """Is the textual-form network address a multicast address?
  94
  95     @param text: the textual address
  96     @raises ValueError: the address family cannot be determined from the input.
  97     @rtype: bool
  98     """
  99     try:
 100         first = ord(dns.ipv4.inet_aton(text)[0])
 101         return (first >= 224 and first <= 239)
 102     except:
 103         try:
 104             first = ord(dns.ipv6.inet_aton(text)[0])
 105             return (first == 255)
 106         except:
 107             raise ValueError
 108