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347 lines
11 KiB
347 lines
11 KiB
# Copyright (C) Dnspython Contributors, see LICENSE for text of ISC license
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# Copyright (C) 2001-2017 Nominum, Inc.
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#
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# Permission to use, copy, modify, and distribute this software and its
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# documentation for any purpose with or without fee is hereby granted,
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# provided that the above copyright notice and this permission notice
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# appear in all copies.
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#
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# THE SOFTWARE IS PROVIDED "AS IS" AND NOMINUM DISCLAIMS ALL WARRANTIES
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# WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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# MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL NOMINUM BE LIABLE FOR
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# ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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# WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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# ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
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# OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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"""DNS rdatasets (an rdataset is a set of rdatas of a given type and class)"""
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import random
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from io import StringIO
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import struct
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import dns.exception
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import dns.rdatatype
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import dns.rdataclass
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import dns.rdata
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import dns.set
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from ._compat import string_types
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# define SimpleSet here for backwards compatibility
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SimpleSet = dns.set.Set
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class DifferingCovers(dns.exception.DNSException):
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"""An attempt was made to add a DNS SIG/RRSIG whose covered type
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is not the same as that of the other rdatas in the rdataset."""
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class IncompatibleTypes(dns.exception.DNSException):
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"""An attempt was made to add DNS RR data of an incompatible type."""
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class Rdataset(dns.set.Set):
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"""A DNS rdataset."""
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__slots__ = ['rdclass', 'rdtype', 'covers', 'ttl']
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def __init__(self, rdclass, rdtype, covers=dns.rdatatype.NONE, ttl=0):
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"""Create a new rdataset of the specified class and type.
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*rdclass*, an ``int``, the rdataclass.
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*rdtype*, an ``int``, the rdatatype.
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*covers*, an ``int``, the covered rdatatype.
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*ttl*, an ``int``, the TTL.
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"""
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super(Rdataset, self).__init__()
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self.rdclass = rdclass
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self.rdtype = rdtype
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self.covers = covers
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self.ttl = ttl
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def _clone(self):
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obj = super(Rdataset, self)._clone()
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obj.rdclass = self.rdclass
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obj.rdtype = self.rdtype
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obj.covers = self.covers
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obj.ttl = self.ttl
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return obj
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def update_ttl(self, ttl):
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"""Perform TTL minimization.
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Set the TTL of the rdataset to be the lesser of the set's current
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TTL or the specified TTL. If the set contains no rdatas, set the TTL
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to the specified TTL.
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*ttl*, an ``int``.
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"""
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if len(self) == 0:
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self.ttl = ttl
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elif ttl < self.ttl:
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self.ttl = ttl
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def add(self, rd, ttl=None):
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"""Add the specified rdata to the rdataset.
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If the optional *ttl* parameter is supplied, then
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``self.update_ttl(ttl)`` will be called prior to adding the rdata.
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*rd*, a ``dns.rdata.Rdata``, the rdata
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*ttl*, an ``int``, the TTL.
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Raises ``dns.rdataset.IncompatibleTypes`` if the type and class
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do not match the type and class of the rdataset.
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Raises ``dns.rdataset.DifferingCovers`` if the type is a signature
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type and the covered type does not match that of the rdataset.
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"""
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#
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# If we're adding a signature, do some special handling to
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# check that the signature covers the same type as the
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# other rdatas in this rdataset. If this is the first rdata
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# in the set, initialize the covers field.
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#
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if self.rdclass != rd.rdclass or self.rdtype != rd.rdtype:
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raise IncompatibleTypes
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if ttl is not None:
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self.update_ttl(ttl)
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if self.rdtype == dns.rdatatype.RRSIG or \
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self.rdtype == dns.rdatatype.SIG:
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covers = rd.covers()
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if len(self) == 0 and self.covers == dns.rdatatype.NONE:
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self.covers = covers
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elif self.covers != covers:
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raise DifferingCovers
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if dns.rdatatype.is_singleton(rd.rdtype) and len(self) > 0:
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self.clear()
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super(Rdataset, self).add(rd)
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def union_update(self, other):
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self.update_ttl(other.ttl)
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super(Rdataset, self).union_update(other)
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def intersection_update(self, other):
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self.update_ttl(other.ttl)
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super(Rdataset, self).intersection_update(other)
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def update(self, other):
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"""Add all rdatas in other to self.
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*other*, a ``dns.rdataset.Rdataset``, the rdataset from which
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to update.
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"""
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self.update_ttl(other.ttl)
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super(Rdataset, self).update(other)
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def __repr__(self):
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if self.covers == 0:
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ctext = ''
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else:
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ctext = '(' + dns.rdatatype.to_text(self.covers) + ')'
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return '<DNS ' + dns.rdataclass.to_text(self.rdclass) + ' ' + \
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dns.rdatatype.to_text(self.rdtype) + ctext + ' rdataset>'
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def __str__(self):
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return self.to_text()
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def __eq__(self, other):
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if not isinstance(other, Rdataset):
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return False
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if self.rdclass != other.rdclass or \
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self.rdtype != other.rdtype or \
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self.covers != other.covers:
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return False
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return super(Rdataset, self).__eq__(other)
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def __ne__(self, other):
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return not self.__eq__(other)
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def to_text(self, name=None, origin=None, relativize=True,
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override_rdclass=None, **kw):
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"""Convert the rdataset into DNS master file format.
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See ``dns.name.Name.choose_relativity`` for more information
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on how *origin* and *relativize* determine the way names
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are emitted.
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Any additional keyword arguments are passed on to the rdata
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``to_text()`` method.
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*name*, a ``dns.name.Name``. If name is not ``None``, emit RRs with
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*name* as the owner name.
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*origin*, a ``dns.name.Name`` or ``None``, the origin for relative
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names.
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*relativize*, a ``bool``. If ``True``, names will be relativized
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to *origin*.
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"""
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if name is not None:
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name = name.choose_relativity(origin, relativize)
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ntext = str(name)
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pad = ' '
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else:
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ntext = ''
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pad = ''
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s = StringIO()
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if override_rdclass is not None:
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rdclass = override_rdclass
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else:
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rdclass = self.rdclass
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if len(self) == 0:
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#
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# Empty rdatasets are used for the question section, and in
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# some dynamic updates, so we don't need to print out the TTL
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# (which is meaningless anyway).
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#
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s.write(u'{}{}{} {}\n'.format(ntext, pad,
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dns.rdataclass.to_text(rdclass),
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dns.rdatatype.to_text(self.rdtype)))
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else:
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for rd in self:
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s.write(u'%s%s%d %s %s %s\n' %
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(ntext, pad, self.ttl, dns.rdataclass.to_text(rdclass),
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dns.rdatatype.to_text(self.rdtype),
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rd.to_text(origin=origin, relativize=relativize,
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**kw)))
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#
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# We strip off the final \n for the caller's convenience in printing
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#
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return s.getvalue()[:-1]
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def to_wire(self, name, file, compress=None, origin=None,
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override_rdclass=None, want_shuffle=True):
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"""Convert the rdataset to wire format.
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*name*, a ``dns.name.Name`` is the owner name to use.
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*file* is the file where the name is emitted (typically a
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BytesIO file).
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*compress*, a ``dict``, is the compression table to use. If
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``None`` (the default), names will not be compressed.
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*origin* is a ``dns.name.Name`` or ``None``. If the name is
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relative and origin is not ``None``, then *origin* will be appended
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to it.
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*override_rdclass*, an ``int``, is used as the class instead of the
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class of the rdataset. This is useful when rendering rdatasets
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associated with dynamic updates.
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*want_shuffle*, a ``bool``. If ``True``, then the order of the
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Rdatas within the Rdataset will be shuffled before rendering.
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Returns an ``int``, the number of records emitted.
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"""
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if override_rdclass is not None:
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rdclass = override_rdclass
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want_shuffle = False
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else:
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rdclass = self.rdclass
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file.seek(0, 2)
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if len(self) == 0:
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name.to_wire(file, compress, origin)
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stuff = struct.pack("!HHIH", self.rdtype, rdclass, 0, 0)
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file.write(stuff)
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return 1
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else:
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if want_shuffle:
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l = list(self)
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random.shuffle(l)
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else:
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l = self
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for rd in l:
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name.to_wire(file, compress, origin)
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stuff = struct.pack("!HHIH", self.rdtype, rdclass,
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self.ttl, 0)
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file.write(stuff)
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start = file.tell()
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rd.to_wire(file, compress, origin)
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end = file.tell()
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assert end - start < 65536
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file.seek(start - 2)
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stuff = struct.pack("!H", end - start)
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file.write(stuff)
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file.seek(0, 2)
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return len(self)
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def match(self, rdclass, rdtype, covers):
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"""Returns ``True`` if this rdataset matches the specified class,
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type, and covers.
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"""
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if self.rdclass == rdclass and \
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self.rdtype == rdtype and \
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self.covers == covers:
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return True
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return False
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def from_text_list(rdclass, rdtype, ttl, text_rdatas):
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"""Create an rdataset with the specified class, type, and TTL, and with
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the specified list of rdatas in text format.
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Returns a ``dns.rdataset.Rdataset`` object.
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"""
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if isinstance(rdclass, string_types):
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rdclass = dns.rdataclass.from_text(rdclass)
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if isinstance(rdtype, string_types):
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rdtype = dns.rdatatype.from_text(rdtype)
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r = Rdataset(rdclass, rdtype)
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r.update_ttl(ttl)
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for t in text_rdatas:
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rd = dns.rdata.from_text(r.rdclass, r.rdtype, t)
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r.add(rd)
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return r
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def from_text(rdclass, rdtype, ttl, *text_rdatas):
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"""Create an rdataset with the specified class, type, and TTL, and with
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the specified rdatas in text format.
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Returns a ``dns.rdataset.Rdataset`` object.
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"""
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return from_text_list(rdclass, rdtype, ttl, text_rdatas)
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def from_rdata_list(ttl, rdatas):
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"""Create an rdataset with the specified TTL, and with
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the specified list of rdata objects.
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Returns a ``dns.rdataset.Rdataset`` object.
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"""
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if len(rdatas) == 0:
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raise ValueError("rdata list must not be empty")
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r = None
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for rd in rdatas:
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if r is None:
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r = Rdataset(rd.rdclass, rd.rdtype)
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r.update_ttl(ttl)
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r.add(rd)
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return r
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def from_rdata(ttl, *rdatas):
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"""Create an rdataset with the specified TTL, and with
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the specified rdata objects.
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Returns a ``dns.rdataset.Rdataset`` object.
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"""
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return from_rdata_list(ttl, rdatas)
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