Viewing file:  edns.py (4.28 KB) -rw-r--r--
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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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