# 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)