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
     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