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

  1  # Copyright (C) 2001-2007, 2009-2011 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 Message Flags.""" 
 17   
 18  # Standard DNS flags 
 19   
 20  QR = 0x8000 
 21  AA = 0x0400 
 22  TC = 0x0200 
 23  RD = 0x0100 
 24  RA = 0x0080 
 25  AD = 0x0020 
 26  CD = 0x0010 
 27   
 28  # EDNS flags 
 29   
 30  DO = 0x8000 
 31   
 32  _by_text = { 
 33      'QR' : QR, 
 34      'AA' : AA, 
 35      'TC' : TC, 
 36      'RD' : RD, 
 37      'RA' : RA, 
 38      'AD' : AD, 
 39      'CD' : CD 
 40  } 
 41   
 42  _edns_by_text = { 
 43      'DO' : DO 
 44  } 
 45   
 46   
 47  # We construct the inverse mappings programmatically to ensure that we 
 48  # cannot make any mistakes (e.g. omissions, cut-and-paste errors) that 
 49  # would cause the mappings not to be true inverses. 
 50   
 51  _by_value = dict([(y, x) for x, y in _by_text.iteritems()]) 
 52   
 53  _edns_by_value = dict([(y, x) for x, y in _edns_by_text.iteritems()]) 
 54   
55 -def _order_flags(table):
56 order = list(table.iteritems()) 57 order.sort() 58 order.reverse() 59 return order
60 61 _flags_order = _order_flags(_by_value) 62 63 _edns_flags_order = _order_flags(_edns_by_value) 64
65 -def _from_text(text, table):
66 flags = 0 67 tokens = text.split() 68 for t in tokens: 69 flags = flags | table[t.upper()] 70 return flags
71
72 -def _to_text(flags, table, order):
73 text_flags = [] 74 for k, v in order: 75 if flags & k != 0: 76 text_flags.append(v) 77 return ' '.join(text_flags)
78
79 -def from_text(text):
80 """Convert a space-separated list of flag text values into a flags 81 value. 82 @rtype: int""" 83 84 return _from_text(text, _by_text)
85
86 -def to_text(flags):
87 """Convert a flags value into a space-separated list of flag text 88 values. 89 @rtype: string""" 90 91 return _to_text(flags, _by_value, _flags_order)
92 93
94 -def edns_from_text(text):
95 """Convert a space-separated list of EDNS flag text values into a EDNS 96 flags value. 97 @rtype: int""" 98 99 return _from_text(text, _edns_by_text)
100
101 -def edns_to_text(flags):
102 """Convert an EDNS flags value into a space-separated list of EDNS flag 103 text values. 104 @rtype: string""" 105 106 return _to_text(flags, _edns_by_value, _edns_flags_order)
107