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Filename : mxbase.py
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# Copyright (C) Dnspython Contributors, see LICENSE for text of ISC license

# Copyright (C) 2003-2007, 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.

"""MX-like base classes."""

import struct

import dns.exception
import dns.immutable
import dns.name
import dns.rdata
import dns.rdtypes.util


@dns.immutable.immutable
class MXBase(dns.rdata.Rdata):
    """Base class for rdata that is like an MX record."""

    __slots__ = ["preference", "exchange"]

    def __init__(self, rdclass, rdtype, preference, exchange):
        super().__init__(rdclass, rdtype)
        self.preference = self._as_uint16(preference)
        self.exchange = self._as_name(exchange)

    def to_text(self, origin=None, relativize=True, **kw):
        exchange = self.exchange.choose_relativity(origin, relativize)
        return "%d %s" % (self.preference, exchange)

    @classmethod
    def from_text(
        cls, rdclass, rdtype, tok, origin=None, relativize=True, relativize_to=None
    ):
        preference = tok.get_uint16()
        exchange = tok.get_name(origin, relativize, relativize_to)
        return cls(rdclass, rdtype, preference, exchange)

    def _to_wire(self, file, compress=None, origin=None, canonicalize=False):
        pref = struct.pack("!H", self.preference)
        file.write(pref)
        self.exchange.to_wire(file, compress, origin, canonicalize)

    @classmethod
    def from_wire_parser(cls, rdclass, rdtype, parser, origin=None):
        preference = parser.get_uint16()
        exchange = parser.get_name(origin)
        return cls(rdclass, rdtype, preference, exchange)

    def _processing_priority(self):
        return self.preference

    @classmethod
    def _processing_order(cls, iterable):
        return dns.rdtypes.util.priority_processing_order(iterable)


@dns.immutable.immutable
class UncompressedMX(MXBase):
    """Base class for rdata that is like an MX record, but whose name
    is not compressed when converted to DNS wire format, and whose
    digestable form is not downcased."""

    def _to_wire(self, file, compress=None, origin=None, canonicalize=False):
        super()._to_wire(file, None, origin, False)


@dns.immutable.immutable
class UncompressedDowncasingMX(MXBase):
    """Base class for rdata that is like an MX record, but whose name
    is not compressed when convert to DNS wire format."""

    def _to_wire(self, file, compress=None, origin=None, canonicalize=False):
        super()._to_wire(file, None, origin, canonicalize)