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- # Copyright (C) 2009, 2011 Nominum, Inc.
- #
- # Permission to use, copy, modify, and distribute this software and its
- # documentation for any purpose with or without fee is hereby granted,
- # provided that the above copyright notice and this permission notice
- # appear in all copies.
- #
- # THE SOFTWARE IS PROVIDED "AS IS" AND NOMINUM DISCLAIMS ALL WARRANTIES
- # WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
- # MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL NOMINUM BE LIABLE FOR
- # ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
- # WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
- # ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
- # OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
- """EDNS Options"""
- NSID = 3
- class Option(object):
- """Base class for all EDNS option types.
- """
- def __init__(self, otype):
- """Initialize an option.
- @param otype: The rdata type
- @type otype: int
- """
- self.otype = otype
- def to_wire(self, file):
- """Convert an option to wire format.
- """
- raise NotImplementedError
- @classmethod
- def from_wire(cls, otype, wire, current, olen):
- """Build an EDNS option object from wire format
- @param otype: The option type
- @type otype: int
- @param wire: The wire-format message
- @type wire: string
- @param current: The offset in wire of the beginning of the rdata.
- @type current: int
- @param olen: The length of the wire-format option data
- @type olen: int
- @rtype: dns.edns.Option instance"""
- raise NotImplementedError
- def _cmp(self, other):
- """Compare an EDNS option with another option of the same type.
- Return < 0 if self < other, 0 if self == other,
- and > 0 if self > other.
- """
- raise NotImplementedError
- def __eq__(self, other):
- if not isinstance(other, Option):
- return False
- if self.otype != other.otype:
- return False
- return self._cmp(other) == 0
- def __ne__(self, other):
- if not isinstance(other, Option):
- return False
- if self.otype != other.otype:
- return False
- return self._cmp(other) != 0
- def __lt__(self, other):
- if not isinstance(other, Option) or \
- self.otype != other.otype:
- return NotImplemented
- return self._cmp(other) < 0
- def __le__(self, other):
- if not isinstance(other, Option) or \
- self.otype != other.otype:
- return NotImplemented
- return self._cmp(other) <= 0
- def __ge__(self, other):
- if not isinstance(other, Option) or \
- self.otype != other.otype:
- return NotImplemented
- return self._cmp(other) >= 0
- def __gt__(self, other):
- if not isinstance(other, Option) or \
- self.otype != other.otype:
- return NotImplemented
- return self._cmp(other) > 0
- class GenericOption(Option):
- """Generate Rdata Class
- This class is used for EDNS option types for which we have no better
- implementation.
- """
- def __init__(self, otype, data):
- super(GenericOption, self).__init__(otype)
- self.data = data
- def to_wire(self, file):
- file.write(self.data)
- @classmethod
- def from_wire(cls, otype, wire, current, olen):
- return cls(otype, wire[current: current + olen])
- def _cmp(self, other):
- if self.data == other.data:
- return 0
- if self.data > other.data:
- return 1
- return -1
- _type_to_class = {
- }
- def get_option_class(otype):
- cls = _type_to_class.get(otype)
- if cls is None:
- cls = GenericOption
- return cls
- def option_from_wire(otype, wire, current, olen):
- """Build an EDNS option object from wire format
- @param otype: The option type
- @type otype: int
- @param wire: The wire-format message
- @type wire: string
- @param current: The offset in wire of the beginning of the rdata.
- @type current: int
- @param olen: The length of the wire-format option data
- @type olen: int
- @rtype: dns.edns.Option instance"""
- cls = get_option_class(otype)
- return cls.from_wire(otype, wire, current, olen)
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