Source Code for Module dns.flags

  1  # Copyright (C) Dnspython Contributors, see LICENSE for text of ISC license 
  2   
  3  # Copyright (C) 2001-2017 Nominum, Inc. 
  4  # 
  5  # Permission to use, copy, modify, and distribute this software and its 
  6  # documentation for any purpose with or without fee is hereby granted, 
  7  # provided that the above copyright notice and this permission notice 
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  9  # 
 10  # THE SOFTWARE IS PROVIDED "AS IS" AND NOMINUM DISCLAIMS ALL WARRANTIES 
 11  # WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 
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 15  # ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT 
 16  # OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 
 17   
 18  """DNS Message Flags.""" 
 19   
 20  # Standard DNS flags 
 21   
 22  #: Query Response 
 23  QR = 0x8000 
 24  #: Authoritative Answer 
 25  AA = 0x0400 
 26  #: Truncated Response 
 27  TC = 0x0200 
 28  #: Recursion Desired 
 29  RD = 0x0100 
 30  #: Recursion Available 
 31  RA = 0x0080 
 32  #: Authentic Data 
 33  AD = 0x0020 
 34  #: Checking Disabled 
 35  CD = 0x0010 
 36   
 37  # EDNS flags 
 38   
 39  #: DNSSEC answer OK 
 40  DO = 0x8000 
 41   
 42  _by_text = { 
 43      'QR': QR, 
 44      'AA': AA, 
 45      'TC': TC, 
 46      'RD': RD, 
 47      'RA': RA, 
 48      'AD': AD, 
 49      'CD': CD 
 50  } 
 51   
 52  _edns_by_text = { 
 53      'DO': DO 
 54  } 
 55   
 56   
 57  # We construct the inverse mappings programmatically to ensure that we 
 58  # cannot make any mistakes (e.g. omissions, cut-and-paste errors) that 
 59  # would cause the mappings not to be true inverses. 
 60   
 61  _by_value = {y: x for x, y in _by_text.items()} 
 62   
 63  _edns_by_value = {y: x for x, y in _edns_by_text.items()} 
 64   
 65   
 66 -def _order_flags(table): 
 67      order = list(table.items()) 
 68      order.sort() 
 69      order.reverse() 
 70      return order 
 71   
 72  _flags_order = _order_flags(_by_value) 
 73   
 74  _edns_flags_order = _order_flags(_edns_by_value) 
 75   
 76   
 77 -def _from_text(text, table): 
 78      flags = 0 
 79      tokens = text.split() 
 80      for t in tokens: 
 81          flags = flags | table[t.upper()] 
 82      return flags 
 83   
 84   
 85 -def _to_text(flags, table, order): 
 86      text_flags = [] 
 87      for k, v in order: 
 88          if flags & k != 0: 
 89              text_flags.append(v) 
 90      return ' '.join(text_flags) 
 91   
 92   
 93 -def from_text(text): 
 94      """Convert a space-separated list of flag text values into a flags 
 95      value. 
 96   
 97      Returns an ``int`` 
 98      """ 
 99   
100      return _from_text(text, _by_text) 
101   
102   
103 -def to_text(flags): 
104      """Convert a flags value into a space-separated list of flag text 
105      values. 
106   
107      Returns a ``text``. 
108      """ 
109   
110      return _to_text(flags, _by_value, _flags_order) 
111   
112   
113 -def edns_from_text(text): 
114      """Convert a space-separated list of EDNS flag text values into a EDNS 
115      flags value. 
116   
117      Returns an ``int`` 
118      """ 
119   
120      return _from_text(text, _edns_by_text) 
121   
122   
123 -def edns_to_text(flags): 
124      """Convert an EDNS flags value into a space-separated list of EDNS flag 
125      text values. 
126   
127      Returns a ``text``. 
128      """ 
129   
130      return _to_text(flags, _edns_by_value, _edns_flags_order) 
131