Package dns :: Module wiredata
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Source Code for Module dns.wiredata

 1  # Copyright (C) 2011 Nominum, Inc. 
 2  # 
 3  # Permission to use, copy, modify, and distribute this software and its 
 4  # documentation for any purpose with or without fee is hereby granted, 
 5  # provided that the above copyright notice and this permission notice 
 6  # appear in all copies. 
 7  # 
 8  # THE SOFTWARE IS PROVIDED "AS IS" AND NOMINUM DISCLAIMS ALL WARRANTIES 
 9  # WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 
10  # MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL NOMINUM BE LIABLE FOR 
11  # ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 
12  # WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 
13  # ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT 
14  # OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 
15   
16  """DNS Wire Data Helper""" 
17   
18  import sys 
19   
20  import dns.exception 
21   
22  # Figure out what constant python passes for an unspecified slice bound. 
23  # It's supposed to be sys.maxint, yet on 64-bit windows sys.maxint is 2^31 - 1 
24  # but Python uses 2^63 - 1 as the constant.  Rather than making pointless 
25  # extra comparisons, duplicating code, or weakening WireData, we just figure 
26  # out what constant Python will use. 
27   
28 -class _SliceUnspecifiedBound(str):
29 - def __getslice__(self, i, j):
30 return j
31 32 _unspecified_bound = _SliceUnspecifiedBound('')[1:] 33
34 -class WireData(str):
35 # WireData is a string with stricter slicing
36 - def __getitem__(self, key):
37 try: 38 return WireData(super(WireData, self).__getitem__(key)) 39 except IndexError: 40 raise dns.exception.FormError
41 - def __getslice__(self, i, j):
42 try: 43 if j == _unspecified_bound: 44 # handle the case where the right bound is unspecified 45 j = len(self) 46 if i < 0 or j < 0: 47 raise dns.exception.FormError 48 # If it's not an empty slice, access left and right bounds 49 # to make sure they're valid 50 if i != j: 51 super(WireData, self).__getitem__(i) 52 super(WireData, self).__getitem__(j - 1) 53 return WireData(super(WireData, self).__getslice__(i, j)) 54 except IndexError: 55 raise dns.exception.FormError
56 - def __iter__(self):
57 i = 0 58 while 1: 59 try: 60 yield self[i] 61 i += 1 62 except dns.exception.FormError: 63 raise StopIteration
64 - def unwrap(self):
65 return str(self)
66
67 -def maybe_wrap(wire):
68 if not isinstance(wire, WireData): 69 return WireData(wire) 70 else: 71 return wire
72