lib/dnspython/dns/edns.py

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