# Copyright (C) Dnspython Contributors, see LICENSE for text of ISC license
# Copyright (C) 2001-2017 Nominum, Inc.
#
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"""DNS rdatasets (an rdataset is a set of rdatas of a given type and class)"""
import dataclasses
import io
import random
import struct
from collections.abc import Collection
from typing import Any, cast
import dns.exception
import dns.immutable
import dns.name
import dns.rdata
import dns.rdataclass
import dns.rdatatype
import dns.set
import dns.ttl
from dns._render_util import prefixed_length
# define SimpleSet here for backwards compatibility
SimpleSet = dns.set.Set
[docs]
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."""
[docs]
class IncompatibleTypes(dns.exception.DNSException):
"""An attempt was made to add DNS RR data of an incompatible type."""
[docs]
@dataclasses.dataclass(frozen=True)
class RdatasetStyle(dns.rdata.RdataStyle):
"""Rdataset text styles
An ``RdatasetStyle`` is also a :py:class:`dns.name.NameStyle` and a
:py:class:`dns.rdata.RdataStyle`. See those classes
for a description of their options.
.. attribute:: override_rdclass
A :py:class:`dns.rdataclass.RdataClass` or ``None``. If not ``None``,
use this class instead of the Rdataset's class.
.. attribute:: want_comments
A ``bool``. If ``True``, emit comments for rdata which have them.
The default is ``False``.
.. attribute:: omit_rdclass
A ``bool``. If ``True``, do not print the RdataClass. The default is
``False``.
.. attribute:: omit_ttl
A ``bool``. If ``True``, do not print the TTL. The default is
``False``. Use of this option may lose information.
.. attribute:: want_generic
A ``bool``. If ``True``, print RdataClass, RdataType, and Rdatas in
the generic format (the "unknown rdata format"). The default is
``False``.
.. attribute:: deduplicate_names
A ``bool``. If ``True``, print whitespace instead of the owner name
when the owner name of an RR is the same as the prior RR's owner name.
The default is ``False``.
.. attribute:: first_name_is_duplicate
A ``bool``. If ``True``, consider the first owner name of the rdataset
as a duplicate too, emitting whitespace for it as well. Useful when
emitting a Node of multiple rdatasets and the current rdataset is not
the first. The default is ``False``.
.. attribute:: default_ttl
An ``int`` or ``None``. If ``None`` (the default), there is no default
TTL. If an integer is specified, any TTL matching that value will be
omitted. When emitting a zonefile, a value other than ``None`` will
cause a ``$TTL`` directive to be emitted.
.. attribute:: name_just
An ``int``. The owner name field justification. Negative values are
left-justified, positive values are right-justified. Zero (the default)
means no justification.
.. attribute:: ttl_just
An ``int``. The TTL field justification. Negative values are
left-justified, positive values are right-justified. Zero (the default)
means no justification.
.. attribute:: rdclass_just
An ``int``. The RdataClass field justification. Negative values are
left-justified, positive values are right-justified. Zero (the default)
means no justification.
.. attribute:: rdtype_just
An ``int``. The RdataType field justification. Negative values are
left-justified, positive values are right-justified. Zero (the default)
means no justification.
"""
override_rdclass: dns.rdataclass.RdataClass | None = None
want_comments: bool = False
omit_rdclass: bool = False
omit_ttl: bool = False
want_generic: bool = False
deduplicate_names: bool = False
first_name_is_duplicate: bool = False
default_ttl: int | None = None
name_just: int = 0
ttl_just: int = 0
rdclass_just: int = 0
rdtype_just: int = 0
def justify(text: str, amount: int):
if amount == 0:
return text
if amount < 0:
return text.ljust(-1 * amount)
else:
return text.rjust(amount)
[docs]
class Rdataset(dns.set.Set):
"""A DNS rdataset."""
__slots__ = ["rdclass", "rdtype", "covers", "ttl"]
def __init__(
self,
rdclass: dns.rdataclass.RdataClass,
rdtype: dns.rdatatype.RdataType,
covers: dns.rdatatype.RdataType = dns.rdatatype.NONE,
ttl: int = 0,
):
"""Create a new rdataset of the specified class and type.
:param rdclass: The rdataclass.
:type rdclass: :py:class:`dns.rdataclass.RdataClass`
:param rdtype: The rdatatype.
:type rdtype: :py:class:`dns.rdatatype.RdataType`
:param covers: The covered rdatatype.
:type covers: :py:class:`dns.rdatatype.RdataType`
:param ttl: The TTL.
:type ttl: int
"""
super().__init__()
self.rdclass = rdclass
self.rdtype: dns.rdatatype.RdataType = rdtype
self.covers: dns.rdatatype.RdataType = covers
self.ttl = ttl
def _clone(self):
obj = cast(Rdataset, super()._clone())
obj.rdclass = self.rdclass
obj.rdtype = self.rdtype
obj.covers = self.covers
obj.ttl = self.ttl
return obj
[docs]
def update_ttl(self, ttl: int) -> None:
"""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.
:param ttl: The candidate TTL value.
:type ttl: int or str
"""
ttl = dns.ttl.make(ttl)
if len(self) == 0:
self.ttl = ttl
elif ttl < self.ttl:
self.ttl = ttl
# pylint: disable=arguments-differ,arguments-renamed
[docs]
def add(self, rd: dns.rdata.Rdata, ttl: int | None = None) -> None: # type: ignore
"""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.
:param rd: The rdata to add.
:type rd: :py:class:`dns.rdata.Rdata`
:param ttl: The TTL.
:type ttl: int or ``None``
: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)
[docs]
def union_update(self, other):
self.update_ttl(other.ttl)
super().union_update(other)
[docs]
def intersection_update(self, other):
self.update_ttl(other.ttl)
super().intersection_update(other)
[docs]
def update(self, other):
"""Add all rdatas in other to self.
:param other: The rdataset from which to update.
:type other: :py:class:`dns.rdataset.Rdataset`
"""
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 "[" + ", ".join(f"<{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)
[docs]
def to_text(
self,
name: dns.name.Name | None = None,
origin: dns.name.Name | None = None,
relativize: bool = True,
override_rdclass: dns.rdataclass.RdataClass | None = None,
want_comments: bool = False,
style: RdatasetStyle | None = None,
**kw: Any,
) -> str:
"""Convert the rdataset into DNS zone 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.
:param name: If not ``None``, emit RRs with this as the owner name.
:type name: :py:class:`dns.name.Name` or ``None``
:param origin: The origin for relative names.
:type origin: :py:class:`dns.name.Name` or ``None``
:param relativize: If ``True``, names will be relativized to *origin*.
:type relativize: bool
:param override_rdclass: If not ``None``, emit records as if they were
of this class.
:type override_rdclass: :py:class:`dns.rdataclass.RdataClass` or ``None``
:param want_comments: If ``True``, emit comments for rdata which have
them. The default is ``False``.
:type want_comments: bool
:param style: If specified, overrides the other parameters except
*name*.
:type style: :py:class:`dns.rdataset.RdatasetStyle` or ``None``
"""
if style is None:
kw = kw.copy()
kw["origin"] = origin
kw["relativize"] = relativize
kw["override_rdclass"] = override_rdclass
kw["want_comments"] = want_comments
style = RdatasetStyle.from_keywords(kw)
return self.to_styled_text(style, name)
[docs]
def to_styled_text(
self, style: RdatasetStyle, name: dns.name.Name | None = None
) -> str:
"""Convert the rdataset into styled text format.
See the documentation for :py:class:`dns.rdataset.RdatasetStyle` for a description
of the style parameters.
"""
if name is not None:
if style.deduplicate_names and style.first_name_is_duplicate:
ntext = " "
else:
ntext = f"{name.to_styled_text(style)} "
ntext = justify(ntext, style.name_just)
else:
ntext = ""
s = io.StringIO()
if style.override_rdclass is not None:
rdclass = style.override_rdclass
else:
rdclass = self.rdclass
if style.omit_rdclass:
rdclass_text = ""
elif style.want_generic:
rdclass_text = f"CLASS{rdclass} "
else:
rdclass_text = f"{dns.rdataclass.to_text(rdclass)} "
rdclass_text = justify(rdclass_text, style.rdclass_just)
if style.want_generic:
rdtype_text = f"TYPE{self.rdtype}"
else:
rdtype_text = f"{dns.rdatatype.to_text(self.rdtype)}"
rdtype_text = justify(rdtype_text, style.rdtype_just)
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(f"{ntext}{rdclass_text}{rdtype_text}\n")
else:
if style.omit_ttl or (
style.default_ttl is not None and self.ttl == style.default_ttl
):
ttl = ""
else:
ttl = f"{self.ttl} "
ttl = justify(ttl, style.ttl_just)
for rd in self:
extra = ""
if style.want_comments:
if rd.rdcomment:
extra = f" ;{rd.rdcomment}"
if style.want_generic:
rdata_text = rd.to_generic().to_styled_text(style)
else:
rdata_text = rd.to_styled_text(style)
s.write(
f"{ntext}{ttl}{rdclass_text}{rdtype_text} {rdata_text}{extra}\n"
)
if style.deduplicate_names:
ntext = " "
ntext = justify(ntext, style.name_just)
#
# We strip off the final \n for the caller's convenience in printing
#
return s.getvalue()[:-1]
[docs]
def to_wire(
self,
name: dns.name.Name,
file: Any,
compress: dns.name.CompressType | None = None,
origin: dns.name.Name | None = None,
override_rdclass: dns.rdataclass.RdataClass | None = None,
want_shuffle: bool = True,
) -> int:
"""Convert the rdataset to wire format.
:param name: The owner name to use.
:type name: :py:class:`dns.name.Name`
:param file: The file where the name is emitted (typically a
``BytesIO`` file).
:param compress: The compression table to use. If ``None`` (the
default), names will not be compressed.
:type compress: dict or ``None``
:param origin: If the name is relative and *origin* is not ``None``,
*origin* will be appended to it.
:type origin: :py:class:`dns.name.Name` or ``None``
:param override_rdclass: If not ``None``, used as the class instead of
the class of the rdataset. Useful for dynamic update rendering.
:type override_rdclass: int or ``None``
:param want_shuffle: If ``True``, the order of Rdatas within the
Rdataset will be shuffled before rendering.
:type want_shuffle: bool
:returns: The number of records emitted.
:rtype: int
"""
if override_rdclass is not None:
rdclass = override_rdclass
want_shuffle = False
else:
rdclass = self.rdclass
if len(self) == 0:
name.to_wire(file, compress, origin)
file.write(struct.pack("!HHIH", self.rdtype, rdclass, 0, 0))
return 1
else:
l: Rdataset | list[dns.rdata.Rdata]
if want_shuffle:
l = list(self)
random.shuffle(l)
else:
l = self
for rd in l:
name.to_wire(file, compress, origin)
file.write(struct.pack("!HHI", self.rdtype, rdclass, self.ttl))
with prefixed_length(file, 2):
rd.to_wire(file, compress, origin)
return len(self)
[docs]
def match(
self,
rdclass: dns.rdataclass.RdataClass,
rdtype: dns.rdatatype.RdataType,
covers: dns.rdatatype.RdataType,
) -> bool:
"""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
[docs]
def processing_order(self) -> list[dns.rdata.Rdata]:
"""Return rdatas in a valid processing order according to the type's
specification. For example, MX records are in preference order from
lowest to highest preferences, with items of the same preference
shuffled.
For types that do not define a processing order, the rdatas are
simply shuffled.
"""
if len(self) == 0:
return []
else:
return self[0]._processing_order(iter(self)) # pyright: ignore
@dns.immutable.immutable
class ImmutableRdataset(Rdataset): # lgtm[py/missing-equals]
"""An immutable DNS rdataset."""
_clone_class = Rdataset
def __init__(self, rdataset: Rdataset):
"""Create an immutable rdataset from the specified rdataset."""
super().__init__(
rdataset.rdclass, rdataset.rdtype, rdataset.covers, rdataset.ttl
)
self.items = dns.immutable.Dict(rdataset.items)
def update_ttl(self, ttl):
raise TypeError("immutable")
def add(self, rd, ttl=None): # pyright: ignore
raise TypeError("immutable")
def union_update(self, other):
raise TypeError("immutable")
def intersection_update(self, other):
raise TypeError("immutable")
def update(self, other):
raise TypeError("immutable")
def __delitem__(self, i):
raise TypeError("immutable")
# lgtm complains about these not raising ArithmeticError, but there is
# precedent for overrides of these methods in other classes to raise
# TypeError, and it seems like the better exception.
def __ior__(self, other): # lgtm[py/unexpected-raise-in-special-method]
raise TypeError("immutable")
def __iand__(self, other): # lgtm[py/unexpected-raise-in-special-method]
raise TypeError("immutable")
def __iadd__(self, other): # lgtm[py/unexpected-raise-in-special-method]
raise TypeError("immutable")
def __isub__(self, other): # lgtm[py/unexpected-raise-in-special-method]
raise TypeError("immutable")
def clear(self):
raise TypeError("immutable")
def __copy__(self):
return ImmutableRdataset(super().copy()) # pyright: ignore
def copy(self):
return ImmutableRdataset(super().copy()) # pyright: ignore
def union(self, other):
return ImmutableRdataset(super().union(other)) # pyright: ignore
def intersection(self, other):
return ImmutableRdataset(super().intersection(other)) # pyright: ignore
def difference(self, other):
return ImmutableRdataset(super().difference(other)) # pyright: ignore
def symmetric_difference(self, other):
return ImmutableRdataset(super().symmetric_difference(other)) # pyright: ignore
[docs]
def from_text_list(
rdclass: dns.rdataclass.RdataClass | str,
rdtype: dns.rdatatype.RdataType | str,
ttl: int,
text_rdatas: Collection[str],
idna_codec: dns.name.IDNACodec | None = None,
origin: dns.name.Name | None = None,
relativize: bool = True,
relativize_to: dns.name.Name | None = None,
) -> Rdataset:
"""Create an rdataset with the specified class, type, and TTL, and with
the specified list of rdatas in text format.
:param idna_codec: Specifies the IDNA encoder/decoder. If ``None``, the
default IDNA 2003 encoder/decoder is used.
:type idna_codec: :py:class:`dns.name.IDNACodec` or ``None``
:param origin: The origin to use for relative names.
:type origin: :py:class:`dns.name.Name` or ``None``
:param relativize: If ``True``, names will be relativized.
:type relativize: bool
:param relativize_to: The origin to use when relativizing names. If not
set, *origin* is used.
:type relativize_to: :py:class:`dns.name.Name` or ``None``
:rtype: :py:class:`dns.rdataset.Rdataset`
"""
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, origin, relativize, relativize_to, idna_codec
)
r.add(rd)
return r
[docs]
def from_text(
rdclass: dns.rdataclass.RdataClass | str,
rdtype: dns.rdatatype.RdataType | str,
ttl: int,
*text_rdatas: Any,
) -> Rdataset:
"""Create an rdataset with the specified class, type, and TTL, and with
the specified rdatas in text format.
:rtype: :py:class:`dns.rdataset.Rdataset`
"""
return from_text_list(rdclass, rdtype, ttl, cast(Collection[str], text_rdatas))
[docs]
def from_rdata_list(ttl: int, rdatas: Collection[dns.rdata.Rdata]) -> Rdataset:
"""Create an rdataset with the specified TTL, and with
the specified list of rdata objects.
:rtype: :py:class:`dns.rdataset.Rdataset`
"""
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)
assert r is not None
return r
[docs]
def from_rdata(ttl: int, *rdatas: Any) -> Rdataset:
"""Create an rdataset with the specified TTL, and with
the specified rdata objects.
:rtype: :py:class:`dns.rdataset.Rdataset`
"""
return from_rdata_list(ttl, cast(Collection[dns.rdata.Rdata], rdatas))