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# Copyright (C) Dnspython Contributors, see LICENSE for text of ISC license
# Copyright (C) 2001-2017 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.
"""DNS rdatasets (an rdataset is a set of rdatas of a given type and class)"""
import io
import random
import struct
import dns.exception
import dns.rdatatype
import dns.rdataclass
import dns.rdata
import dns.set
# define SimpleSet here for backwards compatibility
SimpleSet = dns.set.Set
class DifferingCovers(dns.exception.DNSException):
"""An attempt was made to add a DNS SIG/RRSIG whose covered type
is not the same as that of the other rdatas in the rdataset."""
class IncompatibleTypes(dns.exception.DNSException):
"""An attempt was made to add DNS RR data of an incompatible type."""
class Rdataset(dns.set.Set):
"""A DNS rdataset."""
__slots__ = ['rdclass', 'rdtype', 'covers', 'ttl']
def __init__(self, rdclass, rdtype, covers=dns.rdatatype.NONE, ttl=0):
"""Create a new rdataset of the specified class and type.
*rdclass*, an ``int``, the rdataclass.
*rdtype*, an ``int``, the rdatatype.
*covers*, an ``int``, the covered rdatatype.
*ttl*, an ``int``, the TTL.
"""
super().__init__()
self.rdclass = rdclass
self.rdtype = rdtype
self.covers = covers
self.ttl = ttl
def _clone(self):
obj = super()._clone()
obj.rdclass = self.rdclass
obj.rdtype = self.rdtype
obj.covers = self.covers
obj.ttl = self.ttl
return obj
def update_ttl(self, ttl):
"""Perform TTL minimization.
Set the TTL of the rdataset to be the lesser of the set's current
TTL or the specified TTL. If the set contains no rdatas, set the TTL
to the specified TTL.
*ttl*, an ``int``.
"""
if len(self) == 0:
self.ttl = ttl
elif ttl < self.ttl:
self.ttl = ttl
def add(self, rd, ttl=None):
"""Add the specified rdata to the rdataset.
If the optional *ttl* parameter is supplied, then
``self.update_ttl(ttl)`` will be called prior to adding the rdata.
*rd*, a ``dns.rdata.Rdata``, the rdata
*ttl*, an ``int``, the TTL.
Raises ``dns.rdataset.IncompatibleTypes`` if the type and class
do not match the type and class of the rdataset.
Raises ``dns.rdataset.DifferingCovers`` if the type is a signature
type and the covered type does not match that of the rdataset.
"""
#
# If we're adding a signature, do some special handling to
# check that the signature covers the same type as the
# other rdatas in this rdataset. If this is the first rdata
# in the set, initialize the covers field.
#
if self.rdclass != rd.rdclass or self.rdtype != rd.rdtype:
raise IncompatibleTypes
if ttl is not None:
self.update_ttl(ttl)
if self.rdtype == dns.rdatatype.RRSIG or \
self.rdtype == dns.rdatatype.SIG:
covers = rd.covers()
if len(self) == 0 and self.covers == dns.rdatatype.NONE:
self.covers = covers
elif self.covers != covers:
raise DifferingCovers
if dns.rdatatype.is_singleton(rd.rdtype) and len(self) > 0:
self.clear()
super().add(rd)
def union_update(self, other):
self.update_ttl(other.ttl)
super().union_update(other)
def intersection_update(self, other):
self.update_ttl(other.ttl)
super().intersection_update(other)
def update(self, other):
"""Add all rdatas in other to self.
*other*, a ``dns.rdataset.Rdataset``, the rdataset from which
to update.
"""
self.update_ttl(other.ttl)
super().update(other)
def _rdata_repr(self):
def maybe_truncate(s):
if len(s) > 100:
return s[:100] + '...'
return s
return '[%s]' % ', '.join('<%s>' % maybe_truncate(str(rr))
for rr in self)
def __repr__(self):
if self.covers == 0:
ctext = ''
else:
ctext = '(' + dns.rdatatype.to_text(self.covers) + ')'
return '<DNS ' + dns.rdataclass.to_text(self.rdclass) + ' ' + \
dns.rdatatype.to_text(self.rdtype) + ctext + \
' rdataset: ' + self._rdata_repr() + '>'
def __str__(self):
return self.to_text()
def __eq__(self, other):
if not isinstance(other, Rdataset):
return False
if self.rdclass != other.rdclass or \
self.rdtype != other.rdtype or \
self.covers != other.covers:
return False
return super().__eq__(other)
def __ne__(self, other):
return not self.__eq__(other)
def to_text(self, name=None, origin=None, relativize=True,
override_rdclass=None, **kw):
"""Convert the rdataset into DNS master file format.
See ``dns.name.Name.choose_relativity`` for more information
on how *origin* and *relativize* determine the way names
are emitted.
Any additional keyword arguments are passed on to the rdata
``to_text()`` method.
*name*, a ``dns.name.Name``. If name is not ``None``, emit RRs with
*name* as the owner name.
*origin*, a ``dns.name.Name`` or ``None``, the origin for relative
names.
*relativize*, a ``bool``. If ``True``, names will be relativized
to *origin*.
"""
if name is not None:
name = name.choose_relativity(origin, relativize)
ntext = str(name)
pad = ' '
else:
ntext = ''
pad = ''
s = io.StringIO()
if override_rdclass is not None:
rdclass = override_rdclass
else:
rdclass = self.rdclass
if len(self) == 0:
#
# Empty rdatasets are used for the question section, and in
# some dynamic updates, so we don't need to print out the TTL
# (which is meaningless anyway).
#
s.write('{}{}{} {}\n'.format(ntext, pad,
dns.rdataclass.to_text(rdclass),
dns.rdatatype.to_text(self.rdtype)))
else:
for rd in self:
s.write('%s%s%d %s %s %s\n' %
(ntext, pad, self.ttl, dns.rdataclass.to_text(rdclass),
dns.rdatatype.to_text(self.rdtype),
rd.to_text(origin=origin, relativize=relativize,
**kw)))
#
# We strip off the final \n for the caller's convenience in printing
#
return s.getvalue()[:-1]
def to_wire(self, name, file, compress=None, origin=None,
override_rdclass=None, want_shuffle=True):
"""Convert the rdataset to wire format.
*name*, a ``dns.name.Name`` is the owner name to use.
*file* is the file where the name is emitted (typically a
BytesIO file).
*compress*, a ``dict``, is the compression table to use. If
``None`` (the default), names will not be compressed.
*origin* is a ``dns.name.Name`` or ``None``. If the name is
relative and origin is not ``None``, then *origin* will be appended
to it.
*override_rdclass*, an ``int``, is used as the class instead of the
class of the rdataset. This is useful when rendering rdatasets
associated with dynamic updates.
*want_shuffle*, a ``bool``. If ``True``, then the order of the
Rdatas within the Rdataset will be shuffled before rendering.
Returns an ``int``, the number of records emitted.
"""
if override_rdclass is not None:
rdclass = override_rdclass
want_shuffle = False
else:
rdclass = self.rdclass
file.seek(0, 2)
if len(self) == 0:
name.to_wire(file, compress, origin)
stuff = struct.pack("!HHIH", self.rdtype, rdclass, 0, 0)
file.write(stuff)
return 1
else:
if want_shuffle:
l = list(self)
random.shuffle(l)
else:
l = self
for rd in l:
name.to_wire(file, compress, origin)
stuff = struct.pack("!HHIH", self.rdtype, rdclass,
self.ttl, 0)
file.write(stuff)
start = file.tell()
rd.to_wire(file, compress, origin)
end = file.tell()
assert end - start < 65536
file.seek(start - 2)
stuff = struct.pack("!H", end - start)
file.write(stuff)
file.seek(0, 2)
return len(self)
def match(self, rdclass, rdtype, covers):
"""Returns ``True`` if this rdataset matches the specified class,
type, and covers.
"""
if self.rdclass == rdclass and \
self.rdtype == rdtype and \
self.covers == covers:
return True
return False
def from_text_list(rdclass, rdtype, ttl, text_rdatas, idna_codec=None):
"""Create an rdataset with the specified class, type, and TTL, and with
the specified list of rdatas in text format.
*idna_codec*, a ``dns.name.IDNACodec``, specifies the IDNA
encoder/decoder to use; if ``None``, the default IDNA 2003
encoder/decoder is used.
Returns a ``dns.rdataset.Rdataset`` object.
"""
rdclass = dns.rdataclass.RdataClass.make(rdclass)
rdtype = dns.rdatatype.RdataType.make(rdtype)
r = Rdataset(rdclass, rdtype)
r.update_ttl(ttl)
for t in text_rdatas:
rd = dns.rdata.from_text(r.rdclass, r.rdtype, t, idna_codec=idna_codec)
r.add(rd)
return r
def from_text(rdclass, rdtype, ttl, *text_rdatas):
"""Create an rdataset with the specified class, type, and TTL, and with
the specified rdatas in text format.
Returns a ``dns.rdataset.Rdataset`` object.
"""
return from_text_list(rdclass, rdtype, ttl, text_rdatas)
def from_rdata_list(ttl, rdatas):
"""Create an rdataset with the specified TTL, and with
the specified list of rdata objects.
Returns a ``dns.rdataset.Rdataset`` object.
"""
if len(rdatas) == 0:
raise ValueError("rdata list must not be empty")
r = None
for rd in rdatas:
if r is None:
r = Rdataset(rd.rdclass, rd.rdtype)
r.update_ttl(ttl)
r.add(rd)
return r
def from_rdata(ttl, *rdatas):
"""Create an rdataset with the specified TTL, and with
the specified rdata objects.
Returns a ``dns.rdataset.Rdataset`` object.
"""
return from_rdata_list(ttl, rdatas)
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