# 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 Messages"""
import contextlib
import dataclasses
import enum
import io
import time
from typing import Any, cast
import dns.edns
import dns.entropy
import dns.enum
import dns.exception
import dns.flags
import dns.name
import dns.opcode
import dns.rcode
import dns.rdata
import dns.rdataclass
import dns.rdataset
import dns.rdatatype
import dns.rdtypes.ANY.OPT
import dns.rdtypes.ANY.SOA
import dns.rdtypes.ANY.TSIG
import dns.renderer
import dns.rrset
import dns.tokenizer
import dns.tsig
import dns.ttl
import dns.wire
[docs]
class TrailingJunk(dns.exception.FormError):
"""The DNS packet passed to from_wire() has extra junk at the end of it."""
[docs]
class BadEDNS(dns.exception.FormError):
"""An OPT record occurred somewhere other than
the additional data section."""
[docs]
class BadTSIG(dns.exception.FormError):
"""A TSIG record occurred somewhere other than the end of
the additional data section."""
[docs]
class UnknownTSIGKey(dns.exception.DNSException):
"""A TSIG with an unknown key was received."""
[docs]
class Truncated(dns.exception.DNSException):
"""The truncated flag is set."""
supp_kwargs = {"message"}
# We do this as otherwise mypy complains about unexpected keyword argument
# idna_exception
def __init__(self, *args, **kwargs):
super().__init__(*args, **kwargs)
def message(self):
"""As much of the message as could be processed.
:rtype: :py:class:`dns.message.Message`
"""
return self.kwargs["message"]
[docs]
class NotQueryResponse(dns.exception.DNSException):
"""Message is not a response to a query."""
[docs]
class AnswerForNXDOMAIN(dns.exception.DNSException):
"""The rcode is NXDOMAIN but an answer was found."""
class NoPreviousName(dns.exception.SyntaxError):
"""No previous name was known."""
class MessageSection(dns.enum.IntEnum):
"""Message sections"""
QUESTION = 0
ANSWER = 1
AUTHORITY = 2
ADDITIONAL = 3
@classmethod
def _maximum(cls):
return 3
class MessageError:
def __init__(self, exception: Exception, offset: int):
self.exception = exception
self.offset = offset
DEFAULT_EDNS_PAYLOAD = dns.renderer.DEFAULT_EDNS_PAYLOAD
MAX_CHAIN = 16
IndexKeyType = tuple[
int,
dns.name.Name,
dns.rdataclass.RdataClass,
dns.rdatatype.RdataType,
dns.rdatatype.RdataType | None,
dns.rdataclass.RdataClass | None,
]
IndexType = dict[IndexKeyType, dns.rrset.RRset]
SectionType = int | str | list[dns.rrset.RRset]
[docs]
@dataclasses.dataclass(frozen=True)
class MessageStyle(dns.rdataset.RdatasetStyle):
"""Message text styles.
A ``MessageStyle`` is also a :py:class:`dns.name.NameStyle` and a
:py:class:`dns.rdata.RdataStyle`, and a :py:class:`dns.rdataset.RdatasetStyle`.
See those classes for a description of their options.
There are currently no message-specific style options, but if that changes they
will be documented here.
"""
[docs]
class Message:
"""A DNS message."""
_section_enum = MessageSection
def __init__(self, id: int | None = None):
if id is None:
self.id = dns.entropy.random_16()
else:
self.id = id
self.flags = 0
self.sections: list[list[dns.rrset.RRset]] = [[], [], [], []]
self.opt: dns.rrset.RRset | None = None
self.request_payload = 0
self.pad = 0
self.keyring: Any = None
self.tsig: dns.rrset.RRset | None = None
self.want_tsig_sign = False
self.request_mac = b""
self.xfr = False
self.origin: dns.name.Name | None = None
self.tsig_ctx: Any | None = None
self.index: IndexType = {}
self.errors: list[MessageError] = []
self.time = 0.0
self.wire: bytes | None = None
@property
def question(self) -> list[dns.rrset.RRset]:
"""The question section."""
return self.sections[0]
@question.setter
def question(self, v):
self.sections[0] = v
@property
def answer(self) -> list[dns.rrset.RRset]:
"""The answer section."""
return self.sections[1]
@answer.setter
def answer(self, v):
self.sections[1] = v
@property
def authority(self) -> list[dns.rrset.RRset]:
"""The authority section."""
return self.sections[2]
@authority.setter
def authority(self, v):
self.sections[2] = v
@property
def additional(self) -> list[dns.rrset.RRset]:
"""The additional data section."""
return self.sections[3]
@additional.setter
def additional(self, v):
self.sections[3] = v
def __repr__(self):
return "<DNS message, ID " + repr(self.id) + ">"
def __str__(self):
return self.to_text()
[docs]
def to_text(
self,
origin: dns.name.Name | None = None,
relativize: bool = True,
style: MessageStyle | None = None,
**kw: Any,
) -> str:
"""Convert the message to text.
The *origin*, *relativize*, and any other keyword
arguments are passed to the RRset ``to_text()`` method.
:param style: If specified, overrides *origin* and *relativize*.
:type style: :py:class:`dns.rdataset.RdatasetStyle` or ``None``
:rtype: str
"""
if style is None:
kw = kw.copy()
kw["origin"] = origin
kw["relativize"] = relativize
style = MessageStyle.from_keywords(kw)
return self.to_styled_text(style)
[docs]
def to_styled_text(self, style: MessageStyle) -> str:
"""Convert the message to styled text.
:param style: The style to use for formatting.
:type style: :py:class:`dns.message.MessageStyle`
:rtype: str
"""
s = io.StringIO()
s.write(f"id {self.id}\n")
s.write(f"opcode {dns.opcode.to_text(self.opcode())}\n")
s.write(f"rcode {dns.rcode.to_text(self.rcode())}\n")
s.write(f"flags {dns.flags.to_text(self.flags)}\n")
if self.edns >= 0:
s.write(f"edns {self.edns}\n")
if self.ednsflags != 0:
s.write(f"eflags {dns.flags.edns_to_text(self.ednsflags)}\n")
s.write(f"payload {self.payload}\n")
for opt in self.options:
s.write(f"option {opt.to_text()}\n")
for name, which in self._section_enum.__members__.items():
s.write(f";{name}\n")
for rrset in self.section_from_number(which):
s.write(rrset.to_styled_text(style))
s.write("\n")
if self.tsig is not None:
s.write(self.tsig.to_styled_text(style))
s.write("\n")
#
# We strip off the final \n so the caller can print the result without
# doing weird things to get around eccentricities in Python print
# formatting
#
return s.getvalue()[:-1]
def __eq__(self, other):
"""Two messages are equal if they have the same content in the
header, question, answer, and authority sections.
:rtype: bool
"""
if not isinstance(other, Message):
return False
if self.id != other.id:
return False
if self.flags != other.flags:
return False
for i, section in enumerate(self.sections):
other_section = other.sections[i]
for n in section:
if n not in other_section:
return False
for n in other_section:
if n not in section:
return False
return True
def __ne__(self, other):
return not self.__eq__(other)
[docs]
def is_response(self, other: "Message") -> bool:
"""Is *other* a response to this message?
:param other: The message to check.
:type other: :py:class:`dns.message.Message`
:rtype: bool
"""
if (
other.flags & dns.flags.QR == 0
or self.id != other.id
or dns.opcode.from_flags(self.flags) != dns.opcode.from_flags(other.flags)
):
return False
if other.rcode() in {
dns.rcode.FORMERR,
dns.rcode.SERVFAIL,
dns.rcode.NOTIMP,
dns.rcode.REFUSED,
}:
# We don't check the question section in these cases if
# the other question section is empty, even though they
# still really ought to have a question section.
if len(other.question) == 0:
return True
if dns.opcode.is_update(self.flags):
# This is assuming the "sender doesn't include anything
# from the update", but we don't care to check the other
# case, which is that all the sections are returned and
# identical.
return True
for n in self.question:
if n not in other.question:
return False
for n in other.question:
if n not in self.question:
return False
return True
[docs]
def section_number(self, section: list[dns.rrset.RRset]) -> int:
"""Return the "section number" of the specified section for use
in indexing.
:param section: One of the section attributes of this message.
:raises ValueError: If the section is not known.
:rtype: int
"""
for i, our_section in enumerate(self.sections):
if section is our_section:
return self._section_enum(i)
raise ValueError("unknown section")
[docs]
def section_from_number(self, number: int) -> list[dns.rrset.RRset]:
"""Return the section list associated with the specified section
number.
:param number: A section number (``int``) or text name of a section.
:raises ValueError: If the section is not known.
:rtype: list
"""
section = self._section_enum.make(number)
return self.sections[section]
[docs]
def find_rrset(
self,
section: SectionType,
name: dns.name.Name,
rdclass: dns.rdataclass.RdataClass,
rdtype: dns.rdatatype.RdataType,
covers: dns.rdatatype.RdataType = dns.rdatatype.NONE,
deleting: dns.rdataclass.RdataClass | None = None,
create: bool = False,
force_unique: bool = False,
idna_codec: dns.name.IDNACodec | None = None,
) -> dns.rrset.RRset:
"""Find the RRset with the given attributes in the specified section.
*section* may be an ``int`` section number, a ``str`` section name, or
one of the section list attributes of this message. For example::
my_message.find_rrset(my_message.answer, name, rdclass, rdtype)
my_message.find_rrset(dns.message.ANSWER, name, rdclass, rdtype)
my_message.find_rrset("ANSWER", name, rdclass, rdtype)
:param name: The owner name.
:type name: :py:class:`dns.name.Name` or ``str``
:param rdclass: The rdata class.
:type rdclass: :py:class:`dns.rdataclass.RdataClass` or ``str``
:param rdtype: The rdata type.
:type rdtype: :py:class:`dns.rdatatype.RdataType` or ``str``
:param covers: The covered type; default is ``dns.rdatatype.NONE``.
:type covers: :py:class:`dns.rdatatype.RdataType` or ``str``
:param deleting: The deleting value; default is ``None``.
:type deleting: :py:class:`dns.rdataclass.RdataClass`, ``str``, or ``None``
:param create: If ``True``, create and append the RRset if not found.
:type create: bool
:param force_unique: If ``True`` and *create* is ``True``, always create
a new RRset even if a matching one exists. Useful for DDNS updates.
:type force_unique: bool
:param idna_codec: The IDNA encoder/decoder. Defaults to IDNA 2003.
:type idna_codec: :py:class:`dns.name.IDNACodec` or ``None``
:raises KeyError: If the RRset was not found and *create* is ``False``.
:rtype: :py:class:`dns.rrset.RRset`
"""
if isinstance(section, int):
section_number = section
section = self.section_from_number(section_number)
elif isinstance(section, str):
section_number = self._section_enum.from_text(section)
section = self.section_from_number(section_number)
else:
section_number = self.section_number(section)
if isinstance(name, str):
name = dns.name.from_text(name, idna_codec=idna_codec)
rdtype = dns.rdatatype.RdataType.make(rdtype)
rdclass = dns.rdataclass.RdataClass.make(rdclass)
covers = dns.rdatatype.RdataType.make(covers)
if deleting is not None:
deleting = dns.rdataclass.RdataClass.make(deleting)
key = (section_number, name, rdclass, rdtype, covers, deleting)
if not force_unique:
if self.index is not None:
rrset = self.index.get(key)
if rrset is not None:
return rrset
else:
for rrset in section:
if rrset.full_match(name, rdclass, rdtype, covers, deleting):
return rrset
if not create:
raise KeyError
rrset = dns.rrset.RRset(name, rdclass, rdtype, covers, deleting)
section.append(rrset)
if self.index is not None:
self.index[key] = rrset
return rrset
[docs]
def get_rrset(
self,
section: SectionType,
name: dns.name.Name,
rdclass: dns.rdataclass.RdataClass,
rdtype: dns.rdatatype.RdataType,
covers: dns.rdatatype.RdataType = dns.rdatatype.NONE,
deleting: dns.rdataclass.RdataClass | None = None,
create: bool = False,
force_unique: bool = False,
idna_codec: dns.name.IDNACodec | None = None,
) -> dns.rrset.RRset | None:
"""Get the RRset with the given attributes in the specified section.
Like :py:meth:`find_rrset` but returns ``None`` instead of raising
:py:exc:`KeyError` when the RRset is not found.
*section* may be an ``int`` section number, a ``str`` section name, or
one of the section list attributes of this message.
:param name: The owner name.
:type name: :py:class:`dns.name.Name` or ``str``
:param rdclass: The rdata class.
:type rdclass: :py:class:`dns.rdataclass.RdataClass` or ``str``
:param rdtype: The rdata type.
:type rdtype: :py:class:`dns.rdatatype.RdataType` or ``str``
:param covers: The covered type; default is ``dns.rdatatype.NONE``.
:type covers: :py:class:`dns.rdatatype.RdataType` or ``str``
:param deleting: The deleting value; default is ``None``.
:type deleting: :py:class:`dns.rdataclass.RdataClass`, ``str``, or ``None``
:param create: If ``True``, create and append the RRset if not found.
:type create: bool
:param force_unique: If ``True`` and *create* is ``True``, always create
a new RRset even if a matching one exists.
:type force_unique: bool
:param idna_codec: The IDNA encoder/decoder. Defaults to IDNA 2003.
:type idna_codec: :py:class:`dns.name.IDNACodec` or ``None``
:returns: The matching RRset, or ``None`` if not found.
:rtype: :py:class:`dns.rrset.RRset` or ``None``
"""
try:
rrset = self.find_rrset(
section,
name,
rdclass,
rdtype,
covers,
deleting,
create,
force_unique,
idna_codec,
)
except KeyError:
rrset = None
return rrset
[docs]
def section_count(self, section: SectionType) -> int:
"""Returns the number of records in the specified section.
:param section: An ``int`` section number, a ``str`` section name, or
one of the section attributes of this message. For example::
my_message.section_count(my_message.answer)
my_message.section_count(dns.message.ANSWER)
my_message.section_count("ANSWER")
"""
if isinstance(section, int):
section_number = section
section = self.section_from_number(section_number)
elif isinstance(section, str):
section_number = self._section_enum.from_text(section)
section = self.section_from_number(section_number)
else:
section_number = self.section_number(section)
count = sum(max(1, len(rrs)) for rrs in section)
if section_number == MessageSection.ADDITIONAL:
if self.opt is not None:
count += 1
if self.tsig is not None:
count += 1
return count
def _compute_opt_reserve(self) -> int:
"""Compute the size required for the OPT RR, padding excluded"""
if not self.opt:
return 0
# 1 byte for the root name, 10 for the standard RR fields
size = 11
# This would be more efficient if options had a size() method, but we won't
# worry about that for now. We also don't worry if there is an existing padding
# option, as it is unlikely and probably harmless, as the worst case is that we
# may add another, and this seems to be legal.
opt_rdata = cast(dns.rdtypes.ANY.OPT.OPT, self.opt[0])
for option in opt_rdata.options:
wire = option.to_wire()
# We add 4 here to account for the option type and length
size += len(wire) + 4
if self.pad:
# Padding will be added, so again add the option type and length.
size += 4
return size
def _compute_tsig_reserve(self) -> int:
"""Compute the size required for the TSIG RR"""
# This would be more efficient if TSIGs had a size method, but we won't
# worry about for now. Also, we can't really cope with the potential
# compressibility of the TSIG owner name, so we estimate with the uncompressed
# size. We will disable compression when TSIG and padding are both is active
# so that the padding comes out right.
if not self.tsig:
return 0
f = io.BytesIO()
self.tsig.to_wire(f)
return len(f.getvalue())
[docs]
def to_wire(
self,
origin: dns.name.Name | None = None,
max_size: int = 0,
multi: bool = False,
tsig_ctx: Any | None = None,
prepend_length: bool = False,
prefer_truncation: bool = False,
**kw: Any,
) -> bytes:
"""Return the message in DNS compressed wire format.
Additional keyword arguments are passed to the RRset ``to_wire()``
method.
:param origin: Origin to append to relative names. If ``None``, the
message's own origin (if any) is used.
:type origin: :py:class:`dns.name.Name` or ``None``
:param max_size: Maximum wire format size; 0 means use the request
payload or 65535.
:type max_size: int
:param multi: ``True`` if this message is part of a multi-message sequence.
:type multi: bool
:param tsig_ctx: Ongoing TSIG context for zone transfer signing.
:param prepend_length: If ``True``, prepend the 2-byte message length
(useful for TCP/TLS/QUIC).
:type prepend_length: bool
:param prefer_truncation: If ``True``, truncate instead of raising when
the message exceeds *max_size*. Sets TC if truncation is before the
additional section.
:type prefer_truncation: bool
:raises dns.exception.TooBig: If *max_size* is exceeded and
*prefer_truncation* is ``False``.
:rtype: bytes
"""
if origin is None and self.origin is not None:
origin = self.origin
if max_size == 0:
if self.request_payload != 0:
max_size = self.request_payload
else:
max_size = 65535
if max_size < 512:
max_size = 512
elif max_size > 65535:
max_size = 65535
r = dns.renderer.Renderer(self.id, self.flags, max_size, origin)
opt_reserve = self._compute_opt_reserve()
r.reserve(opt_reserve)
tsig_reserve = self._compute_tsig_reserve()
r.reserve(tsig_reserve)
try:
for rrset in self.question:
r.add_question(rrset.name, rrset.rdtype, rrset.rdclass)
for rrset in self.answer:
r.add_rrset(dns.renderer.ANSWER, rrset, **kw)
for rrset in self.authority:
r.add_rrset(dns.renderer.AUTHORITY, rrset, **kw)
for rrset in self.additional:
r.add_rrset(dns.renderer.ADDITIONAL, rrset, **kw)
except dns.exception.TooBig:
if prefer_truncation:
if r.section < dns.renderer.ADDITIONAL:
r.flags |= dns.flags.TC
else:
raise
r.release_reserved()
if self.opt is not None:
r.add_opt(self.opt, self.pad, opt_reserve, tsig_reserve)
r.write_header()
if self.tsig is not None:
if self.want_tsig_sign:
new_tsig, ctx = dns.tsig.sign(
r.get_wire(),
self.keyring,
self.tsig[0],
int(time.time()),
self.request_mac,
tsig_ctx,
multi,
)
self.tsig.clear()
self.tsig.add(new_tsig)
if multi:
self.tsig_ctx = ctx
r.add_rrset(dns.renderer.ADDITIONAL, self.tsig)
r.write_header()
wire = r.get_wire()
self.wire = wire
if prepend_length:
wire = len(wire).to_bytes(2, "big") + wire
return wire
@staticmethod
def _make_tsig(
keyname, algorithm, time_signed, fudge, mac, original_id, error, other
):
return dns.renderer._make_tsig(
keyname, algorithm, time_signed, fudge, mac, original_id, error, other
)
[docs]
def use_tsig(
self,
keyring: Any,
keyname: dns.name.Name | str | None = None,
fudge: int = 300,
original_id: int | None = None,
tsig_error: int = 0,
other_data: bytes = b"",
algorithm: dns.name.Name | str = dns.tsig.default_algorithm,
) -> None:
"""Arrange for a TSIG signature to be added when sending.
:param keyring: The TSIG keyring or key. A ``dict`` maps
:py:class:`dns.name.Name` keys to :py:class:`dns.tsig.Key` objects
or ``bytes`` secrets. If a ``dict`` is given without *keyname*, the
first key in the dict is used. A callable is invoked with the message
and *keyname* and must return a key.
:type keyring: dict, callable, or :py:class:`dns.tsig.Key`
:param keyname: The TSIG key name. Ignored if *keyring* is a
:py:class:`dns.tsig.Key`. Defaults to ``None``.
:type keyname: :py:class:`dns.name.Name`, ``str``, or ``None``
:param fudge: The TSIG time fudge.
:type fudge: int
:param original_id: The TSIG original id. Defaults to the message id.
:type original_id: int or ``None``
:param tsig_error: The TSIG error code.
:type tsig_error: int
:param other_data: The TSIG other data.
:type other_data: bytes
:param algorithm: The TSIG algorithm. Only used when *keyring* is a
``dict`` and the key entry is ``bytes``.
:type algorithm: :py:class:`dns.name.Name` or ``str``
"""
if isinstance(keyring, dns.tsig.Key):
key = keyring
keyname = key.name
elif callable(keyring):
key = keyring(self, keyname)
else:
if isinstance(keyname, str):
keyname = dns.name.from_text(keyname)
if keyname is None:
keyname = next(iter(keyring))
key = keyring[keyname]
if isinstance(key, bytes):
key = dns.tsig.Key(keyname, key, algorithm)
self.keyring = key
if original_id is None:
original_id = self.id
self.tsig = self._make_tsig(
keyname,
self.keyring.algorithm,
0,
fudge,
b"\x00" * dns.tsig.mac_sizes[self.keyring.algorithm],
original_id,
tsig_error,
other_data,
)
self.want_tsig_sign = True
@property
def keyname(self) -> dns.name.Name | None:
if self.tsig:
return self.tsig.name
else:
return None
@property
def keyalgorithm(self) -> dns.name.Name | None:
if self.tsig:
rdata = cast(dns.rdtypes.ANY.TSIG.TSIG, self.tsig[0])
return rdata.algorithm
else:
return None
@property
def mac(self) -> bytes | None:
if self.tsig:
rdata = cast(dns.rdtypes.ANY.TSIG.TSIG, self.tsig[0])
return rdata.mac
else:
return None
@property
def tsig_error(self) -> int | None:
if self.tsig:
rdata = cast(dns.rdtypes.ANY.TSIG.TSIG, self.tsig[0])
return rdata.error
else:
return None
@property
def had_tsig(self) -> bool:
return bool(self.tsig)
@staticmethod
def _make_opt(flags=0, payload=DEFAULT_EDNS_PAYLOAD, options=None):
return dns.renderer._make_opt(flags, payload, options)
[docs]
def use_edns(
self,
edns: int | bool | None = 0,
ednsflags: int = 0,
payload: int = DEFAULT_EDNS_PAYLOAD,
request_payload: int | None = None,
options: list[dns.edns.Option] | None = None,
pad: int = 0,
) -> None:
"""Configure EDNS behavior.
:param edns: The EDNS level to use. Specifying ``None``, ``False``, or
``-1`` means "do not use EDNS" (other parameters are ignored).
Specifying ``True`` is equivalent to specifying 0 (use EDNS0).
:type edns: int or ``None``
:param ednsflags: The EDNS flag values.
:type ednsflags: int
:param payload: The EDNS sender's payload field — the maximum UDP
datagram size the sender can handle (i.e. how big a response can be).
:type payload: int
:param request_payload: The EDNS payload size to use when sending.
Defaults to the value of *payload*.
:type request_payload: int or ``None``
:param options: The EDNS options.
:type options: list of :py:class:`dns.edns.Option` or ``None``
:param pad: If 0 (the default), do not pad; otherwise add padding bytes
to make the message size a multiple of *pad*. When nonzero, an EDNS
PADDING option is always added.
:type pad: int
"""
if edns is None or edns is False:
edns = -1
elif edns is True:
edns = 0
if edns < 0:
self.opt = None
self.request_payload = 0
else:
# make sure the EDNS version in ednsflags agrees with edns
ednsflags &= 0xFF00FFFF
ednsflags |= edns << 16
if options is None:
options = []
self.opt = self._make_opt(ednsflags, payload, options)
if request_payload is None:
request_payload = payload
self.request_payload = request_payload
if pad < 0:
raise ValueError("pad must be non-negative")
self.pad = pad
@property
def edns(self) -> int:
if self.opt:
return (self.ednsflags & 0xFF0000) >> 16
else:
return -1
@property
def ednsflags(self) -> int:
if self.opt:
return self.opt.ttl
else:
return 0
@ednsflags.setter
def ednsflags(self, v):
if self.opt:
self.opt.ttl = v
elif v:
self.opt = self._make_opt(v)
@property
def payload(self) -> int:
if self.opt:
rdata = cast(dns.rdtypes.ANY.OPT.OPT, self.opt[0])
return rdata.payload
else:
return 0
@property
def options(self) -> tuple:
if self.opt:
rdata = cast(dns.rdtypes.ANY.OPT.OPT, self.opt[0])
return rdata.options
else:
return ()
[docs]
def want_dnssec(self, wanted: bool = True) -> None:
"""Enable or disable 'DNSSEC desired' flag in requests.
:param wanted: If ``True``, DNSSEC data is desired in the response,
EDNS is enabled if required, and the DO bit is set. If ``False``,
the DO bit is cleared if EDNS is enabled.
:type wanted: bool
"""
if wanted:
self.ednsflags |= dns.flags.DO
elif self.opt:
self.ednsflags &= ~int(dns.flags.DO)
[docs]
def rcode(self) -> dns.rcode.Rcode:
"""Return the rcode.
:rtype: :py:class:`dns.rcode.Rcode`
"""
return dns.rcode.from_flags(int(self.flags), int(self.ednsflags))
[docs]
def set_rcode(self, rcode: dns.rcode.Rcode) -> None:
"""Set the rcode.
*rcode*, a ``dns.rcode.Rcode``, is the rcode to set.
"""
value, evalue = dns.rcode.to_flags(rcode)
self.flags &= 0xFFF0
self.flags |= value
self.ednsflags &= 0x00FFFFFF
self.ednsflags |= evalue
[docs]
def opcode(self) -> dns.opcode.Opcode:
"""Return the opcode.
:rtype: :py:class:`dns.opcode.Opcode`
"""
return dns.opcode.from_flags(int(self.flags))
[docs]
def set_opcode(self, opcode: dns.opcode.Opcode) -> None:
"""Set the opcode.
:param opcode: The opcode to set.
:type opcode: :py:class:`dns.opcode.Opcode`
"""
self.flags &= 0x87FF
self.flags |= dns.opcode.to_flags(opcode)
[docs]
def get_options(self, otype: dns.edns.OptionType) -> list[dns.edns.Option]:
"""Return the list of options of the specified type."""
return [option for option in self.options if option.otype == otype]
[docs]
def extended_errors(self) -> list[dns.edns.EDEOption]:
"""Return the list of Extended DNS Error (EDE) options in the message"""
return cast(list[dns.edns.EDEOption], self.get_options(dns.edns.OptionType.EDE))
def _get_one_rr_per_rrset(self, value):
# What the caller picked is fine.
return value
# pylint: disable=unused-argument
def _parse_rr_header(self, section, name, rdclass, rdtype):
return (rdclass, rdtype, None, False)
# pylint: enable=unused-argument
def _parse_special_rr_header(self, section, count, position, name, rdclass, rdtype):
if rdtype == dns.rdatatype.OPT:
if (
section != MessageSection.ADDITIONAL
or self.opt
or name != dns.name.root
):
raise BadEDNS
elif rdtype == dns.rdatatype.TSIG:
if (
section != MessageSection.ADDITIONAL
or rdclass != dns.rdatatype.ANY
or position != count - 1
):
raise BadTSIG
return (rdclass, rdtype, None, False)
[docs]
class ChainingResult:
"""The result of a call to dns.message.QueryMessage.resolve_chaining().
The ``answer`` attribute is the answer RRSet, or ``None`` if it doesn't
exist.
The ``canonical_name`` attribute is the canonical name after all
chaining has been applied (this is the same name as ``rrset.name`` in cases
where rrset is not ``None``).
The ``minimum_ttl`` attribute is the minimum TTL, i.e. the TTL to
use if caching the data. It is the smallest of all the CNAME TTLs
and either the answer TTL if it exists or the SOA TTL and SOA
minimum values for negative answers.
The ``cnames`` attribute is a list of all the CNAME RRSets followed to
get to the canonical name.
"""
def __init__(
self,
canonical_name: dns.name.Name,
answer: dns.rrset.RRset | None,
minimum_ttl: int,
cnames: list[dns.rrset.RRset],
):
self.canonical_name = canonical_name
self.answer = answer
self.minimum_ttl = minimum_ttl
self.cnames = cnames
[docs]
class QueryMessage(Message):
[docs]
def resolve_chaining(self) -> ChainingResult:
"""Follow the CNAME chain in the response to determine the answer
RRset.
:raises dns.message.NotQueryResponse: If the message is not a response.
:raises dns.message.ChainTooLong: If the CNAME chain is too long.
:raises dns.message.AnswerForNXDOMAIN: If the rcode is NXDOMAIN but
an answer was found.
:raises dns.exception.FormError: If the question count is not 1.
:rtype: :py:class:`dns.message.ChainingResult`
"""
if self.flags & dns.flags.QR == 0:
raise NotQueryResponse
if len(self.question) != 1:
raise dns.exception.FormError
question = self.question[0]
qname = question.name
min_ttl = dns.ttl.MAX_TTL
answer = None
count = 0
cnames = []
while count < MAX_CHAIN:
try:
answer = self.find_rrset(
self.answer, qname, question.rdclass, question.rdtype
)
min_ttl = min(min_ttl, answer.ttl)
break
except KeyError:
if question.rdtype != dns.rdatatype.CNAME:
try:
crrset = self.find_rrset(
self.answer, qname, question.rdclass, dns.rdatatype.CNAME
)
cnames.append(crrset)
min_ttl = min(min_ttl, crrset.ttl)
for rd in crrset:
qname = rd.target
break
count += 1
continue
except KeyError:
# Exit the chaining loop
break
else:
# Exit the chaining loop
break
if count >= MAX_CHAIN:
raise ChainTooLong
if self.rcode() == dns.rcode.NXDOMAIN and answer is not None:
raise AnswerForNXDOMAIN
if answer is None:
# Further minimize the TTL with NCACHE.
auname = qname
while True:
# Look for an SOA RR whose owner name is a superdomain
# of qname.
try:
srrset = self.find_rrset(
self.authority, auname, question.rdclass, dns.rdatatype.SOA
)
srdata = cast(dns.rdtypes.ANY.SOA.SOA, srrset[0])
min_ttl = min(min_ttl, srrset.ttl, srdata.minimum)
break
except KeyError:
try:
auname = auname.parent()
except dns.name.NoParent:
break
return ChainingResult(qname, answer, min_ttl, cnames)
[docs]
def canonical_name(self) -> dns.name.Name:
"""Return the canonical name of the first name in the question
section.
:raises dns.message.NotQueryResponse: If the message is not a response.
:raises dns.message.ChainTooLong: If the CNAME chain is too long.
:raises dns.message.AnswerForNXDOMAIN: If the rcode is NXDOMAIN but
an answer was found.
:raises dns.exception.FormError: If the question count is not 1.
"""
return self.resolve_chaining().canonical_name
def _maybe_import_update():
# We avoid circular imports by doing this here. We do it in another
# function as doing it in _message_factory_from_opcode() makes "dns"
# a local symbol, and the first line fails :)
# pylint: disable=redefined-outer-name,import-outside-toplevel,unused-import
import dns.update # noqa: F401
def _message_factory_from_opcode(opcode):
if opcode == dns.opcode.QUERY:
return QueryMessage
elif opcode == dns.opcode.UPDATE:
_maybe_import_update()
return dns.update.UpdateMessage # pyright: ignore
else:
return Message
class _WireReader:
"""Wire format reader.
parser: the binary parser
message: The message object being built
initialize_message: Callback to set message parsing options
question_only: Are we only reading the question?
one_rr_per_rrset: Put each RR into its own RRset?
keyring: TSIG keyring
ignore_trailing: Ignore trailing junk at end of request?
multi: Is this message part of a multi-message sequence?
DNS dynamic updates.
continue_on_error: try to extract as much information as possible from
the message, accumulating MessageErrors in the *errors* attribute instead of
raising them.
"""
def __init__(
self,
wire,
initialize_message,
question_only=False,
one_rr_per_rrset=False,
ignore_trailing=False,
keyring=None,
multi=False,
continue_on_error=False,
):
self.parser = dns.wire.Parser(wire)
self.message = None
self.initialize_message = initialize_message
self.question_only = question_only
self.one_rr_per_rrset = one_rr_per_rrset
self.ignore_trailing = ignore_trailing
self.keyring = keyring
self.multi = multi
self.continue_on_error = continue_on_error
self.errors = []
def _get_question(self, section_number, qcount):
"""Read the next *qcount* records from the wire data and add them to
the question section.
"""
assert self.message is not None
section = self.message.sections[section_number]
for _ in range(qcount):
qname = self.parser.get_name(self.message.origin)
rdtype, rdclass = self.parser.get_struct("!HH")
rdclass, rdtype, _, _ = self.message._parse_rr_header(
section_number, qname, rdclass, rdtype
)
self.message.find_rrset(
section, qname, rdclass, rdtype, create=True, force_unique=True
)
def _add_error(self, e):
self.errors.append(MessageError(e, self.parser.current))
def _get_section(self, section_number, count):
"""Read the next I{count} records from the wire data and add them to
the specified section.
section_number: the section of the message to which to add records
count: the number of records to read
"""
assert self.message is not None
section = self.message.sections[section_number]
force_unique = self.one_rr_per_rrset
for i in range(count):
rr_start = self.parser.current
absolute_name = self.parser.get_name()
if self.message.origin is not None:
name = absolute_name.relativize(self.message.origin)
else:
name = absolute_name
rdtype, rdclass, ttl, rdlen = self.parser.get_struct("!HHIH")
if rdtype in (dns.rdatatype.OPT, dns.rdatatype.TSIG):
(
rdclass,
rdtype,
deleting,
empty,
) = self.message._parse_special_rr_header(
section_number, count, i, name, rdclass, rdtype
)
else:
rdclass, rdtype, deleting, empty = self.message._parse_rr_header(
section_number, name, rdclass, rdtype
)
rdata_start = self.parser.current
try:
if empty:
if rdlen > 0:
raise dns.exception.FormError
rd = None
covers = dns.rdatatype.NONE
else:
with self.parser.restrict_to(rdlen):
rd = dns.rdata.from_wire_parser(
rdclass, # pyright: ignore
rdtype,
self.parser,
self.message.origin,
)
covers = rd.covers()
if self.message.xfr and rdtype == dns.rdatatype.SOA:
force_unique = True
if rdtype == dns.rdatatype.OPT:
self.message.opt = dns.rrset.from_rdata(name, ttl, rd)
elif rdtype == dns.rdatatype.TSIG:
trd = cast(dns.rdtypes.ANY.TSIG.TSIG, rd)
if self.keyring is None or self.keyring is True:
raise UnknownTSIGKey("got signed message without keyring")
elif isinstance(self.keyring, dict):
key = self.keyring.get(absolute_name)
if isinstance(key, bytes):
key = dns.tsig.Key(absolute_name, key, trd.algorithm)
elif callable(self.keyring):
key = self.keyring(self.message, absolute_name)
else:
key = self.keyring
if key is None:
raise UnknownTSIGKey(f"key '{name}' unknown")
if key:
self.message.keyring = key
self.message.tsig_ctx = dns.tsig.validate(
self.parser.wire,
key,
absolute_name,
rd,
int(time.time()),
self.message.request_mac,
rr_start,
self.message.tsig_ctx,
self.multi,
)
self.message.tsig = dns.rrset.from_rdata(absolute_name, 0, rd)
else:
rrset = self.message.find_rrset(
section,
name,
rdclass, # pyright: ignore
rdtype,
covers,
deleting,
True,
force_unique,
)
if rd is not None:
if ttl > 0x7FFFFFFF:
ttl = 0
rrset.add(rd, ttl)
except Exception as e:
if self.continue_on_error:
self._add_error(e)
self.parser.seek(rdata_start + rdlen)
else:
raise
def read(self):
"""Read a wire format DNS message and build a dns.message.Message
object."""
if self.parser.remaining() < 12:
raise ShortHeader
id, flags, qcount, ancount, aucount, adcount = self.parser.get_struct("!HHHHHH")
factory = _message_factory_from_opcode(dns.opcode.from_flags(flags))
self.message = factory(id=id)
self.message.flags = dns.flags.Flag(flags)
self.message.wire = self.parser.wire
self.initialize_message(self.message)
self.one_rr_per_rrset = self.message._get_one_rr_per_rrset(
self.one_rr_per_rrset
)
try:
self._get_question(MessageSection.QUESTION, qcount)
if self.question_only:
return self.message
self._get_section(MessageSection.ANSWER, ancount)
self._get_section(MessageSection.AUTHORITY, aucount)
self._get_section(MessageSection.ADDITIONAL, adcount)
if not self.ignore_trailing and self.parser.remaining() != 0:
raise TrailingJunk
if self.multi and self.message.tsig_ctx and not self.message.had_tsig:
self.message.tsig_ctx.update(self.parser.wire)
except Exception as e:
if self.continue_on_error:
self._add_error(e)
else:
raise
return self.message
[docs]
def from_wire(
wire: bytes,
keyring: Any | None = None,
request_mac: bytes | None = b"",
xfr: bool = False,
origin: dns.name.Name | None = None,
tsig_ctx: dns.tsig.HMACTSig | dns.tsig.GSSTSig | None = None,
multi: bool = False,
question_only: bool = False,
one_rr_per_rrset: bool = False,
ignore_trailing: bool = False,
raise_on_truncation: bool = False,
continue_on_error: bool = False,
) -> Message:
"""Convert a DNS wire format message into a message object.
:param keyring: The key or keyring for TSIG validation. ``None`` or
``True`` causes TSIG-signed messages to fail; ``False`` disables
validation.
:type keyring: :py:class:`dns.tsig.Key`, dict, bool, or ``None``
:param request_mac: MAC of the TSIG-signed request this message responds
to, if any.
:type request_mac: bytes or ``None``
:param xfr: ``True`` if this message is part of a zone transfer.
:type xfr: bool
:param origin: Zone origin for zone transfers; names are relativized to
this if not ``None``.
:type origin: :py:class:`dns.name.Name` or ``None``
:param tsig_ctx: Ongoing TSIG context for zone transfer validation.
:param multi: ``True`` if this message is part of a multi-message sequence.
:type multi: bool
:param question_only: If ``True``, read only the question section.
:type question_only: bool
:param one_rr_per_rrset: If ``True``, put each RR into its own RRset.
:type one_rr_per_rrset: bool
:param ignore_trailing: If ``True``, ignore trailing octets after the
message.
:type ignore_trailing: bool
:param raise_on_truncation: If ``True``, raise
:py:exc:`dns.message.Truncated` when the TC bit is set.
:type raise_on_truncation: bool
:param continue_on_error: If ``True``, try to continue parsing on errors
and accumulate them in the message's ``errors`` attribute.
:type continue_on_error: bool
:raises dns.message.ShortHeader: If the message is less than 12 octets.
:raises dns.message.TrailingJunk: If trailing octets are present and
*ignore_trailing* is ``False``.
:raises dns.message.BadEDNS: If an OPT record is in the wrong section.
:raises dns.message.BadTSIG: If a TSIG record is not the last additional
record.
:raises dns.message.Truncated: If the TC flag is set and
*raise_on_truncation* is ``True``.
:rtype: :py:class:`dns.message.Message`
"""
# We permit None for request_mac solely for backwards compatibility
if request_mac is None:
request_mac = b""
def initialize_message(message):
message.request_mac = request_mac
message.xfr = xfr
message.origin = origin
message.tsig_ctx = tsig_ctx
reader = _WireReader(
wire,
initialize_message,
question_only,
one_rr_per_rrset,
ignore_trailing,
keyring,
multi,
continue_on_error,
)
try:
m = reader.read()
except dns.exception.FormError:
if (
reader.message
and (reader.message.flags & dns.flags.TC)
and raise_on_truncation
):
raise Truncated(message=reader.message)
else:
raise
# Reading a truncated message might not have any errors, so we
# have to do this check here too.
if m.flags & dns.flags.TC and raise_on_truncation:
raise Truncated(message=m)
if continue_on_error:
m.errors = reader.errors
return m
class _TextReader:
"""Text format reader.
tok: the tokenizer.
message: The message object being built.
DNS dynamic updates.
last_name: The most recently read name when building a message object.
one_rr_per_rrset: Put each RR into its own RRset?
origin: The origin for relative names
relativize: relativize names?
relativize_to: the origin to relativize to.
"""
def __init__(
self,
text: Any,
idna_codec: dns.name.IDNACodec | None,
one_rr_per_rrset: bool = False,
origin: dns.name.Name | None = None,
relativize: bool = True,
relativize_to: dns.name.Name | None = None,
):
self.message: Message | None = None # mypy: ignore
self.tok = dns.tokenizer.Tokenizer(text, idna_codec=idna_codec)
self.last_name = None
self.one_rr_per_rrset = one_rr_per_rrset
self.origin = origin
self.relativize = relativize
self.relativize_to = relativize_to
self.id = None
self.edns = -1
self.ednsflags = 0
self.payload = DEFAULT_EDNS_PAYLOAD
self.rcode = None
self.opcode = dns.opcode.QUERY
self.flags = 0
def _header_line(self, _):
"""Process one line from the text format header section."""
token = self.tok.get()
what = token.value
if what == "id":
self.id = self.tok.get_int()
elif what == "flags":
while True:
token = self.tok.get()
if not token.is_identifier():
self.tok.unget(token)
break
self.flags = self.flags | dns.flags.from_text(token.value)
elif what == "edns":
self.edns = self.tok.get_int()
self.ednsflags = self.ednsflags | (self.edns << 16)
elif what == "eflags":
if self.edns < 0:
self.edns = 0
while True:
token = self.tok.get()
if not token.is_identifier():
self.tok.unget(token)
break
self.ednsflags = self.ednsflags | dns.flags.edns_from_text(token.value)
elif what == "payload":
self.payload = self.tok.get_int()
if self.edns < 0:
self.edns = 0
elif what == "opcode":
text = self.tok.get_string()
self.opcode = dns.opcode.from_text(text)
self.flags = self.flags | dns.opcode.to_flags(self.opcode)
elif what == "rcode":
text = self.tok.get_string()
self.rcode = dns.rcode.from_text(text)
else:
raise UnknownHeaderField
self.tok.get_eol()
def _question_line(self, section_number):
"""Process one line from the text format question section."""
assert self.message is not None
section = self.message.sections[section_number]
token = self.tok.get(want_leading=True)
if not token.is_whitespace():
self.last_name = self.tok.as_name(
token, self.message.origin, self.relativize, self.relativize_to
)
name = self.last_name
if name is None:
raise NoPreviousName
token = self.tok.get()
if not token.is_identifier():
raise dns.exception.SyntaxError
# Class
try:
rdclass = dns.rdataclass.from_text(token.value)
token = self.tok.get()
if not token.is_identifier():
raise dns.exception.SyntaxError
except dns.exception.SyntaxError:
raise dns.exception.SyntaxError
except Exception:
rdclass = dns.rdataclass.IN
# Type
rdtype = dns.rdatatype.from_text(token.value)
rdclass, rdtype, _, _ = self.message._parse_rr_header(
section_number, name, rdclass, rdtype
)
self.message.find_rrset(
section, name, rdclass, rdtype, create=True, force_unique=True
)
self.tok.get_eol()
def _rr_line(self, section_number):
"""Process one line from the text format answer, authority, or
additional data sections.
"""
assert self.message is not None
section = self.message.sections[section_number]
# Name
token = self.tok.get(want_leading=True)
if not token.is_whitespace():
self.last_name = self.tok.as_name(
token, self.message.origin, self.relativize, self.relativize_to
)
name = self.last_name
if name is None:
raise NoPreviousName
token = self.tok.get()
if not token.is_identifier():
raise dns.exception.SyntaxError
# TTL
try:
ttl = int(token.value, 0)
token = self.tok.get()
if not token.is_identifier():
raise dns.exception.SyntaxError
except dns.exception.SyntaxError:
raise dns.exception.SyntaxError
except Exception:
ttl = 0
# Class
try:
rdclass = dns.rdataclass.from_text(token.value)
token = self.tok.get()
if not token.is_identifier():
raise dns.exception.SyntaxError
except dns.exception.SyntaxError:
raise dns.exception.SyntaxError
except Exception:
rdclass = dns.rdataclass.IN
# Type
rdtype = dns.rdatatype.from_text(token.value)
rdclass, rdtype, deleting, empty = self.message._parse_rr_header(
section_number, name, rdclass, rdtype
)
token = self.tok.get()
if empty and not token.is_eol_or_eof():
raise dns.exception.SyntaxError
if not empty and token.is_eol_or_eof():
raise dns.exception.UnexpectedEnd
if not token.is_eol_or_eof():
self.tok.unget(token)
rd = dns.rdata.from_text(
rdclass,
rdtype,
self.tok,
self.message.origin,
self.relativize,
self.relativize_to,
)
covers = rd.covers()
else:
rd = None
covers = dns.rdatatype.NONE
rrset = self.message.find_rrset(
section,
name,
rdclass,
rdtype,
covers,
deleting,
True,
self.one_rr_per_rrset,
)
if rd is not None:
rrset.add(rd, ttl)
def _make_message(self):
factory = _message_factory_from_opcode(self.opcode)
message = factory(id=self.id)
message.flags = self.flags
if self.edns >= 0:
message.use_edns(self.edns, self.ednsflags, self.payload)
if self.rcode:
message.set_rcode(self.rcode)
if self.origin:
message.origin = self.origin
return message
def read(self):
"""Read a text format DNS message and build a dns.message.Message
object."""
line_method = self._header_line
section_number = None
while 1:
token = self.tok.get(True, True)
if token.is_eol_or_eof():
break
if token.is_comment():
u = token.value.upper()
if u == "HEADER":
line_method = self._header_line
if self.message:
message = self.message
else:
# If we don't have a message, create one with the current
# opcode, so that we know which section names to parse.
message = self._make_message()
try:
section_number = message._section_enum.from_text(u)
# We found a section name. If we don't have a message,
# use the one we just created.
if not self.message:
self.message = message
self.one_rr_per_rrset = message._get_one_rr_per_rrset(
self.one_rr_per_rrset
)
if section_number == MessageSection.QUESTION:
line_method = self._question_line
else:
line_method = self._rr_line
except Exception:
# It's just a comment.
pass
self.tok.get_eol()
continue
self.tok.unget(token)
line_method(section_number)
if not self.message:
self.message = self._make_message()
return self.message
[docs]
def from_text(
text: str,
idna_codec: dns.name.IDNACodec | None = None,
one_rr_per_rrset: bool = False,
origin: dns.name.Name | None = None,
relativize: bool = True,
relativize_to: dns.name.Name | None = None,
) -> Message:
"""Convert the text format message into a message object.
The reader stops after reading the first blank line in the input to
facilitate reading multiple messages from a single file with
``dns.message.from_file()``.
:param text: The text format message.
:type text: str
:param idna_codec: The IDNA encoder/decoder. Defaults to IDNA 2003.
:type idna_codec: :py:class:`dns.name.IDNACodec` or ``None``
:param one_rr_per_rrset: If ``True``, put each RR into its own RRset.
:type one_rr_per_rrset: bool
: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 relativize to. Defaults to *origin*.
:type relativize_to: :py:class:`dns.name.Name` or ``None``
:raises dns.message.UnknownHeaderField: If a header field is unknown.
:raises dns.exception.SyntaxError: If the text is badly formed.
:rtype: :py:class:`dns.message.Message`
"""
# 'text' can also be a file, but we don't publish that fact
# since it's an implementation detail. The official file
# interface is from_file().
reader = _TextReader(
text, idna_codec, one_rr_per_rrset, origin, relativize, relativize_to
)
return reader.read()
[docs]
def from_file(
f: Any,
idna_codec: dns.name.IDNACodec | None = None,
one_rr_per_rrset: bool = False,
) -> Message:
"""Read the next text format message from the specified file.
Message blocks are separated by a single blank line.
:param f: A file object or a pathname string.
:param idna_codec: The IDNA encoder/decoder. Defaults to IDNA 2003.
:type idna_codec: :py:class:`dns.name.IDNACodec` or ``None``
:param one_rr_per_rrset: If ``True``, put each RR into its own RRset.
:type one_rr_per_rrset: bool
:raises dns.message.UnknownHeaderField: If a header field is unknown.
:raises dns.exception.SyntaxError: If the text is badly formed.
:rtype: :py:class:`dns.message.Message`
"""
if isinstance(f, str):
cm: contextlib.AbstractContextManager = open(f, encoding="utf-8")
else:
cm = contextlib.nullcontext(f)
with cm as f:
reader = _TextReader(f, idna_codec, one_rr_per_rrset)
return reader.read()
assert False # for mypy lgtm[py/unreachable-statement]
[docs]
def make_query(
qname: dns.name.Name | str,
rdtype: dns.rdatatype.RdataType | str,
rdclass: dns.rdataclass.RdataClass | str = dns.rdataclass.IN,
use_edns: int | bool | None = None,
want_dnssec: bool = False,
ednsflags: int | None = None,
payload: int | None = None,
request_payload: int | None = None,
options: list[dns.edns.Option] | None = None,
idna_codec: dns.name.IDNACodec | None = None,
id: int | None = None,
flags: int = dns.flags.RD,
pad: int = 0,
) -> QueryMessage:
"""Make a query message.
The query name, type, and class may be specified as objects of the
appropriate type or as strings. The query id is chosen at random, and
the DNS flags are set to ``dns.flags.RD``.
:param qname: The query name.
:type qname: :py:class:`dns.name.Name` or ``str``
:param rdtype: The desired rdata type.
:type rdtype: :py:class:`dns.rdatatype.RdataType` or ``str``
:param rdclass: The desired rdata class; default is IN.
:type rdclass: :py:class:`dns.rdataclass.RdataClass` or ``str``
:param use_edns: The EDNS level; ``None`` enables EDNS only if other EDNS
parameters are set. See :py:meth:`dns.message.Message.use_edns`.
:type use_edns: int, bool, or ``None``
:param want_dnssec: If ``True``, DNSSEC data is desired.
:type want_dnssec: bool
:param ednsflags: The EDNS flag values.
:type ednsflags: int
:param payload: The EDNS sender payload field (max UDP response size).
:type payload: int
:param request_payload: The EDNS payload size to advertise when sending.
Defaults to *payload*.
:type request_payload: int
:param options: The EDNS options.
:type options: list of :py:class:`dns.edns.Option` or ``None``
:param idna_codec: The IDNA encoder/decoder. Defaults to IDNA 2003.
:type idna_codec: :py:class:`dns.name.IDNACodec` or ``None``
:param id: The query id. Defaults to a random id.
:type id: int or ``None``
:param flags: The query flags. Default is ``dns.flags.RD``.
:type flags: int
:param pad: If non-zero, add EDNS PADDING to make size a multiple of this.
:type pad: int
:rtype: :py:class:`dns.message.QueryMessage`
"""
if isinstance(qname, str):
qname = dns.name.from_text(qname, idna_codec=idna_codec)
rdtype = dns.rdatatype.RdataType.make(rdtype)
rdclass = dns.rdataclass.RdataClass.make(rdclass)
m = QueryMessage(id=id)
m.flags = dns.flags.Flag(flags)
m.find_rrset(m.question, qname, rdclass, rdtype, create=True, force_unique=True)
# only pass keywords on to use_edns if they have been set to a
# non-None value. Setting a field will turn EDNS on if it hasn't
# been configured.
kwargs: dict[str, Any] = {}
if ednsflags is not None:
kwargs["ednsflags"] = ednsflags
if payload is not None:
kwargs["payload"] = payload
if request_payload is not None:
kwargs["request_payload"] = request_payload
if options is not None:
kwargs["options"] = options
if kwargs and use_edns is None:
use_edns = 0
kwargs["edns"] = use_edns
kwargs["pad"] = pad
m.use_edns(**kwargs)
if want_dnssec:
m.want_dnssec(want_dnssec)
return m
[docs]
class CopyMode(enum.Enum):
"""
How should sections be copied when making an update response?
"""
#: Copy no sections; only suitable for testing
NOTHING = 0
#: Copy only the question section, if present.
QUESTION = 1
#: Copy all sections, other than OPT and TSIG RRs.
EVERYTHING = 2
[docs]
def make_response(
query: Message,
recursion_available: bool = False,
our_payload: int = 8192,
fudge: int = 300,
tsig_error: int = 0,
pad: int | None = None,
copy_mode: CopyMode | None = None,
) -> Message:
"""Make a response skeleton for the specified query.
The returned message has all required response infrastructure but no
content. Copied sections are shallow copies, so the query's RRsets
should not be changed.
:param query: The query to respond to.
:type query: :py:class:`dns.message.Message`
:param recursion_available: If ``True``, set the RA bit.
:type recursion_available: bool
:param our_payload: The EDNS payload size to advertise.
:type our_payload: int
:param fudge: The TSIG time fudge.
:type fudge: int
:param tsig_error: The TSIG error code.
:type tsig_error: int
:param pad: If 0, no padding; if not ``None`` pad to a multiple of this
value; if ``None``, follow RFC 8467 (pad to 468 if request was padded).
:type pad: int or ``None``
:param copy_mode: Controls which sections are copied. ``None`` uses the
default for the opcode (currently
:py:attr:`dns.message.CopyMode.QUESTION`).
:type copy_mode: :py:class:`dns.message.CopyMode` or ``None``
:returns: A response message of the same class as *query*.
:rtype: :py:class:`dns.message.Message`
"""
if query.flags & dns.flags.QR:
raise dns.exception.FormError("specified query message is not a query")
opcode = query.opcode()
factory = _message_factory_from_opcode(opcode)
response = factory(id=query.id)
response.flags = dns.flags.QR | (query.flags & dns.flags.RD)
if recursion_available:
response.flags |= dns.flags.RA
response.set_opcode(opcode)
if copy_mode is None:
copy_mode = CopyMode.QUESTION
if copy_mode != CopyMode.NOTHING:
response.question = list(query.question)
if copy_mode == CopyMode.EVERYTHING:
response.answer = list(query.answer)
response.authority = list(query.authority)
response.additional = list(query.additional)
if query.edns >= 0:
if pad is None:
# Set response padding per RFC 8467
pad = 0
for option in query.options:
if option.otype == dns.edns.OptionType.PADDING:
pad = 468
response.use_edns(0, 0, our_payload, query.payload, pad=pad)
if query.had_tsig and query.keyring:
assert query.mac is not None
assert query.keyalgorithm is not None
response.use_tsig(
query.keyring,
query.keyname,
fudge,
None,
tsig_error,
b"",
query.keyalgorithm,
)
response.request_mac = query.mac
return response
### BEGIN generated MessageSection constants
QUESTION = MessageSection.QUESTION
ANSWER = MessageSection.ANSWER
AUTHORITY = MessageSection.AUTHORITY
ADDITIONAL = MessageSection.ADDITIONAL
### END generated MessageSection constants