Source Code for Module dns.edns

  1  # Copyright (C) 2009, 2011 Nominum, Inc. 
  2  # 
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  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. 
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  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  """EDNS Options""" 
 17   
 18  NSID = 3 
 19   
 20   
 21 -class Option(object): 
 22   
 23      """Base class for all EDNS option types. 
 24      """ 
 25   
 26 -    def __init__(self, otype): 
 27          """Initialize an option. 
 28          @param otype: The rdata type 
 29          @type otype: int 
 30          """ 
 31          self.otype = otype 
 32   
 33 -    def to_wire(self, file): 
 34          """Convert an option to wire format. 
 35          """ 
 36          raise NotImplementedError 
 37   
 38      @classmethod 
 39 -    def from_wire(cls, otype, wire, current, olen): 
 40          """Build an EDNS option object from wire format 
 41   
 42          @param otype: The option type 
 43          @type otype: int 
 44          @param wire: The wire-format message 
 45          @type wire: string 
 46          @param current: The offset in wire of the beginning of the rdata. 
 47          @type current: int 
 48          @param olen: The length of the wire-format option data 
 49          @type olen: int 
 50          @rtype: dns.edns.Option instance""" 
 51          raise NotImplementedError 
 52   
 53 -    def _cmp(self, other): 
 54          """Compare an EDNS option with another option of the same type. 
 55          Return < 0 if self < other, 0 if self == other, 
 56          and > 0 if self > other. 
 57          """ 
 58          raise NotImplementedError 
 59   
 60 -    def __eq__(self, other): 
 61          if not isinstance(other, Option): 
 62              return False 
 63          if self.otype != other.otype: 
 64              return False 
 65          return self._cmp(other) == 0 
 66   
 67 -    def __ne__(self, other): 
 68          if not isinstance(other, Option): 
 69              return False 
 70          if self.otype != other.otype: 
 71              return False 
 72          return self._cmp(other) != 0 
 73   
 74 -    def __lt__(self, other): 
 75          if not isinstance(other, Option) or \ 
 76                  self.otype != other.otype: 
 77              return NotImplemented 
 78          return self._cmp(other) < 0 
 79   
 80 -    def __le__(self, other): 
 81          if not isinstance(other, Option) or \ 
 82                  self.otype != other.otype: 
 83              return NotImplemented 
 84          return self._cmp(other) <= 0 
 85   
 86 -    def __ge__(self, other): 
 87          if not isinstance(other, Option) or \ 
 88                  self.otype != other.otype: 
 89              return NotImplemented 
 90          return self._cmp(other) >= 0 
 91   
 92 -    def __gt__(self, other): 
 93          if not isinstance(other, Option) or \ 
 94                  self.otype != other.otype: 
 95              return NotImplemented 
 96          return self._cmp(other) > 0 
 97   
 98   
 99 -class GenericOption(Option): 
100   
101      """Generate Rdata Class 
102   
103      This class is used for EDNS option types for which we have no better 
104      implementation. 
105      """ 
106   
107 -    def __init__(self, otype, data): 
108          super(GenericOption, self).__init__(otype) 
109          self.data = data 
110   
111 -    def to_wire(self, file): 
112          file.write(self.data) 
113   
114      @classmethod 
115 -    def from_wire(cls, otype, wire, current, olen): 
116          return cls(otype, wire[current: current + olen]) 
117   
118 -    def _cmp(self, other): 
119          if self.data == other.data: 
120              return 0 
121          if self.data > other.data: 
122              return 1 
123          return -1 
124   
125  _type_to_class = { 
126  } 
127   
128   
129 -def get_option_class(otype): 
130      cls = _type_to_class.get(otype) 
131      if cls is None: 
132          cls = GenericOption 
133      return cls 
134   
135   
136 -def option_from_wire(otype, wire, current, olen): 
137      """Build an EDNS option object from wire format 
138   
139      @param otype: The option type 
140      @type otype: int 
141      @param wire: The wire-format message 
142      @type wire: string 
143      @param current: The offset in wire of the beginning of the rdata. 
144      @type current: int 
145      @param olen: The length of the wire-format option data 
146      @type olen: int 
147      @rtype: dns.edns.Option instance""" 
148   
149      cls = get_option_class(otype) 
150      return cls.from_wire(otype, wire, current, olen) 
151