Source Code for Module dns.flags

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 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.items()) 
 52   
 53  _edns_by_value = dict((y, x) for x, y in _edns_by_text.items()) 
 54   
 55   
 56 -def _order_flags(table): 
 57      order = list(table.items()) 
 58      order.sort() 
 59      order.reverse() 
 60      return order 
 61   
 62  _flags_order = _order_flags(_by_value) 
 63   
 64  _edns_flags_order = _order_flags(_edns_by_value) 
 65   
 66   
 67 -def _from_text(text, table): 
 68      flags = 0 
 69      tokens = text.split() 
 70      for t in tokens: 
 71          flags = flags | table[t.upper()] 
 72      return flags 
 73   
 74   
 75 -def _to_text(flags, table, order): 
 76      text_flags = [] 
 77      for k, v in order: 
 78          if flags & k != 0: 
 79              text_flags.append(v) 
 80      return ' '.join(text_flags) 
 81   
 82   
 83 -def from_text(text): 
 84      """Convert a space-separated list of flag text values into a flags 
 85      value. 
 86      @rtype: int""" 
 87   
 88      return _from_text(text, _by_text) 
 89   
 90   
 91 -def to_text(flags): 
 92      """Convert a flags value into a space-separated list of flag text 
 93      values. 
 94      @rtype: string""" 
 95   
 96      return _to_text(flags, _by_value, _flags_order) 
 97   
 98   
 99 -def edns_from_text(text): 
100      """Convert a space-separated list of EDNS flag text values into a EDNS 
101      flags value. 
102      @rtype: int""" 
103   
104      return _from_text(text, _edns_by_text) 
105   
106   
107 -def edns_to_text(flags): 
108      """Convert an EDNS flags value into a space-separated list of EDNS flag 
109      text values. 
110      @rtype: string""" 
111   
112      return _to_text(flags, _edns_by_value, _edns_flags_order) 
113