Package dns :: Module wiredata
[hide private]
[frames] | no frames]

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  from ._compat import binary_type, string_types 
 22   
 23  # Figure out what constant python passes for an unspecified slice bound. 
 24  # It's supposed to be sys.maxint, yet on 64-bit windows sys.maxint is 2^31 - 1 
 25  # but Python uses 2^63 - 1 as the constant.  Rather than making pointless 
 26  # extra comparisons, duplicating code, or weakening WireData, we just figure 
 27  # out what constant Python will use. 
 28   
 29   
30 -class _SliceUnspecifiedBound(binary_type):
31
32 - def __getitem__(self, key):
33 return key.stop
34 35 if sys.version_info < (3,):
36 - def __getslice__(self, i, j): # pylint: disable=getslice-method
37 return self.__getitem__(slice(i, j))
38 39 _unspecified_bound = _SliceUnspecifiedBound()[1:] 40 41
42 -class WireData(binary_type):
43 # WireData is a string with stricter slicing 44
45 - def __getitem__(self, key):
46 try: 47 if isinstance(key, slice): 48 # make sure we are not going outside of valid ranges, 49 # do stricter control of boundaries than python does 50 # by default 51 start = key.start 52 stop = key.stop 53 54 if sys.version_info < (3,): 55 if stop == _unspecified_bound: 56 # handle the case where the right bound is unspecified 57 stop = len(self) 58 59 if start < 0 or stop < 0: 60 raise dns.exception.FormError 61 # If it's not an empty slice, access left and right bounds 62 # to make sure they're valid 63 if start != stop: 64 super(WireData, self).__getitem__(start) 65 super(WireData, self).__getitem__(stop - 1) 66 else: 67 for index in (start, stop): 68 if index is None: 69 continue 70 elif abs(index) > len(self): 71 raise dns.exception.FormError 72 73 return WireData(super(WireData, self).__getitem__( 74 slice(start, stop))) 75 return bytearray(self.unwrap())[key] 76 except IndexError: 77 raise dns.exception.FormError
78 79 if sys.version_info < (3,):
80 - def __getslice__(self, i, j): # pylint: disable=getslice-method
81 return self.__getitem__(slice(i, j))
82
83 - def __iter__(self):
84 i = 0 85 while 1: 86 try: 87 yield self[i] 88 i += 1 89 except dns.exception.FormError: 90 raise StopIteration
91
92 - def unwrap(self):
93 return binary_type(self)
94 95
96 -def maybe_wrap(wire):
97 if isinstance(wire, WireData): 98 return wire 99 elif isinstance(wire, binary_type): 100 return WireData(wire) 101 elif isinstance(wire, string_types): 102 return WireData(wire.encode()) 103 raise ValueError("unhandled type %s" % type(wire))
104