Package dns :: Module edns |
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# Source Code for Module dns.edns

      1  # Copyright (C) 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  """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 otype: The rdata type
     27          @type otype: 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.edns.Option instance"""
     48          raise NotImplementedError
     49
     50      from_wire = classmethod(from_wire)
     51
     52 -    def _cmp(self, other):
     53          """Compare an EDNS 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.edns.Option instance"""
    140
    141      cls = get_option_class(otype)
    142      return cls.from_wire(otype, wire, current, olen)
    143