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# Copyright (C) Dnspython Contributors, see LICENSE for text of ISC license
# Copyright (C) 2003-2017 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.
"""Talk to a DNS server."""
import base64
import contextlib
import enum
import errno
import os
import os.path
import selectors
import socket
import struct
import time
from typing import Any, Dict, Optional, Tuple, Union
import dns._features
import dns.exception
import dns.inet
import dns.message
import dns.name
import dns.quic
import dns.rcode
import dns.rdataclass
import dns.rdatatype
import dns.serial
import dns.transaction
import dns.tsig
import dns.xfr
def _remaining(expiration):
if expiration is None:
return None
timeout = expiration - time.time()
if timeout <= 0.0:
raise dns.exception.Timeout
return timeout
def _expiration_for_this_attempt(timeout, expiration):
if expiration is None:
return None
return min(time.time() + timeout, expiration)
_have_httpx = dns._features.have("doh")
if _have_httpx:
import httpcore._backends.sync
import httpx
_CoreNetworkBackend = httpcore.NetworkBackend
_CoreSyncStream = httpcore._backends.sync.SyncStream
class _NetworkBackend(_CoreNetworkBackend):
def __init__(self, resolver, local_port, bootstrap_address, family):
super().__init__()
self._local_port = local_port
self._resolver = resolver
self._bootstrap_address = bootstrap_address
self._family = family
def connect_tcp(
self, host, port, timeout, local_address, socket_options=None
): # pylint: disable=signature-differs
addresses = []
_, expiration = _compute_times(timeout)
if dns.inet.is_address(host):
addresses.append(host)
elif self._bootstrap_address is not None:
addresses.append(self._bootstrap_address)
else:
timeout = _remaining(expiration)
family = self._family
if local_address:
family = dns.inet.af_for_address(local_address)
answers = self._resolver.resolve_name(
host, family=family, lifetime=timeout
)
addresses = answers.addresses()
for address in addresses:
af = dns.inet.af_for_address(address)
if local_address is not None or self._local_port != 0:
source = dns.inet.low_level_address_tuple(
(local_address, self._local_port), af
)
else:
source = None
sock = _make_socket(af, socket.SOCK_STREAM, source)
attempt_expiration = _expiration_for_this_attempt(2.0, expiration)
try:
_connect(
sock,
dns.inet.low_level_address_tuple((address, port), af),
attempt_expiration,
)
return _CoreSyncStream(sock)
except Exception:
pass
raise httpcore.ConnectError
def connect_unix_socket(
self, path, timeout, socket_options=None
): # pylint: disable=signature-differs
raise NotImplementedError
class _HTTPTransport(httpx.HTTPTransport):
def __init__(
self,
*args,
local_port=0,
bootstrap_address=None,
resolver=None,
family=socket.AF_UNSPEC,
**kwargs,
):
if resolver is None:
# pylint: disable=import-outside-toplevel,redefined-outer-name
import dns.resolver
resolver = dns.resolver.Resolver()
super().__init__(*args, **kwargs)
self._pool._network_backend = _NetworkBackend(
resolver, local_port, bootstrap_address, family
)
else:
class _HTTPTransport: # type: ignore
def connect_tcp(self, host, port, timeout, local_address):
raise NotImplementedError
have_doh = _have_httpx
try:
import ssl
except ImportError: # pragma: no cover
class ssl: # type: ignore
CERT_NONE = 0
class WantReadException(Exception):
pass
class WantWriteException(Exception):
pass
class SSLContext:
pass
class SSLSocket:
pass
@classmethod
def create_default_context(cls, *args, **kwargs):
raise Exception("no ssl support") # pylint: disable=broad-exception-raised
# Function used to create a socket. Can be overridden if needed in special
# situations.
socket_factory = socket.socket
class UnexpectedSource(dns.exception.DNSException):
"""A DNS query response came from an unexpected address or port."""
class BadResponse(dns.exception.FormError):
"""A DNS query response does not respond to the question asked."""
class NoDOH(dns.exception.DNSException):
"""DNS over HTTPS (DOH) was requested but the httpx module is not
available."""
class NoDOQ(dns.exception.DNSException):
"""DNS over QUIC (DOQ) was requested but the aioquic module is not
available."""
# for backwards compatibility
TransferError = dns.xfr.TransferError
def _compute_times(timeout):
now = time.time()
if timeout is None:
return (now, None)
else:
return (now, now + timeout)
def _wait_for(fd, readable, writable, _, expiration):
# Use the selected selector class to wait for any of the specified
# events. An "expiration" absolute time is converted into a relative
# timeout.
#
# The unused parameter is 'error', which is always set when
# selecting for read or write, and we have no error-only selects.
if readable and isinstance(fd, ssl.SSLSocket) and fd.pending() > 0:
return True
sel = _selector_class()
events = 0
if readable:
events |= selectors.EVENT_READ
if writable:
events |= selectors.EVENT_WRITE
if events:
sel.register(fd, events)
if expiration is None:
timeout = None
else:
timeout = expiration - time.time()
if timeout <= 0.0:
raise dns.exception.Timeout
if not sel.select(timeout):
raise dns.exception.Timeout
def _set_selector_class(selector_class):
# Internal API. Do not use.
global _selector_class
_selector_class = selector_class
if hasattr(selectors, "PollSelector"):
# Prefer poll() on platforms that support it because it has no
# limits on the maximum value of a file descriptor (plus it will
# be more efficient for high values).
#
# We ignore typing here as we can't say _selector_class is Any
# on python < 3.8 due to a bug.
_selector_class = selectors.PollSelector # type: ignore
else:
_selector_class = selectors.SelectSelector # type: ignore
def _wait_for_readable(s, expiration):
_wait_for(s, True, False, True, expiration)
def _wait_for_writable(s, expiration):
_wait_for(s, False, True, True, expiration)
def _addresses_equal(af, a1, a2):
# Convert the first value of the tuple, which is a textual format
# address into binary form, so that we are not confused by different
# textual representations of the same address
try:
n1 = dns.inet.inet_pton(af, a1[0])
n2 = dns.inet.inet_pton(af, a2[0])
except dns.exception.SyntaxError:
return False
return n1 == n2 and a1[1:] == a2[1:]
def _matches_destination(af, from_address, destination, ignore_unexpected):
# Check that from_address is appropriate for a response to a query
# sent to destination.
if not destination:
return True
if _addresses_equal(af, from_address, destination) or (
dns.inet.is_multicast(destination[0]) and from_address[1:] == destination[1:]
):
return True
elif ignore_unexpected:
return False
raise UnexpectedSource(
f"got a response from {from_address} instead of " f"{destination}"
)
def _destination_and_source(
where, port, source, source_port, where_must_be_address=True
):
# Apply defaults and compute destination and source tuples
# suitable for use in connect(), sendto(), or bind().
af = None
destination = None
try:
af = dns.inet.af_for_address(where)
destination = where
except Exception:
if where_must_be_address:
raise
# URLs are ok so eat the exception
if source:
saf = dns.inet.af_for_address(source)
if af:
# We know the destination af, so source had better agree!
if saf != af:
raise ValueError(
"different address families for source and destination"
)
else:
# We didn't know the destination af, but we know the source,
# so that's our af.
af = saf
if source_port and not source:
# Caller has specified a source_port but not an address, so we
# need to return a source, and we need to use the appropriate
# wildcard address as the address.
try:
source = dns.inet.any_for_af(af)
except Exception:
# we catch this and raise ValueError for backwards compatibility
raise ValueError("source_port specified but address family is unknown")
# Convert high-level (address, port) tuples into low-level address
# tuples.
if destination:
destination = dns.inet.low_level_address_tuple((destination, port), af)
if source:
source = dns.inet.low_level_address_tuple((source, source_port), af)
return (af, destination, source)
def _make_socket(af, type, source, ssl_context=None, server_hostname=None):
s = socket_factory(af, type)
try:
s.setblocking(False)
if source is not None:
s.bind(source)
if ssl_context:
# LGTM gets a false positive here, as our default context is OK
return ssl_context.wrap_socket(
s,
do_handshake_on_connect=False, # lgtm[py/insecure-protocol]
server_hostname=server_hostname,
)
else:
return s
except Exception:
s.close()
raise
def https(
q: dns.message.Message,
where: str,
timeout: Optional[float] = None,
port: int = 443,
source: Optional[str] = None,
source_port: int = 0,
one_rr_per_rrset: bool = False,
ignore_trailing: bool = False,
session: Optional[Any] = None,
path: str = "/dns-query",
post: bool = True,
bootstrap_address: Optional[str] = None,
verify: Union[bool, str] = True,
resolver: Optional["dns.resolver.Resolver"] = None,
family: Optional[int] = socket.AF_UNSPEC,
) -> dns.message.Message:
"""Return the response obtained after sending a query via DNS-over-HTTPS.
*q*, a ``dns.message.Message``, the query to send.
*where*, a ``str``, the nameserver IP address or the full URL. If an IP address is
given, the URL will be constructed using the following schema:
https://<IP-address>:<port>/<path>.
*timeout*, a ``float`` or ``None``, the number of seconds to wait before the query
times out. If ``None``, the default, wait forever.
*port*, a ``int``, the port to send the query to. The default is 443.
*source*, a ``str`` containing an IPv4 or IPv6 address, specifying the source
address. The default is the wildcard address.
*source_port*, an ``int``, the port from which to send the message. The default is
0.
*one_rr_per_rrset*, a ``bool``. If ``True``, put each RR into its own RRset.
*ignore_trailing*, a ``bool``. If ``True``, ignore trailing junk at end of the
received message.
*session*, an ``httpx.Client``. If provided, the client session to use to send the
queries.
*path*, a ``str``. If *where* is an IP address, then *path* will be used to
construct the URL to send the DNS query to.
*post*, a ``bool``. If ``True``, the default, POST method will be used.
*bootstrap_address*, a ``str``, the IP address to use to bypass resolution.
*verify*, a ``bool`` or ``str``. If a ``True``, then TLS certificate verification
of the server is done using the default CA bundle; if ``False``, then no
verification is done; if a `str` then it specifies the path to a certificate file or
directory which will be used for verification.
*resolver*, a ``dns.resolver.Resolver`` or ``None``, the resolver to use for
resolution of hostnames in URLs. If not specified, a new resolver with a default
configuration will be used; note this is *not* the default resolver as that resolver
might have been configured to use DoH causing a chicken-and-egg problem. This
parameter only has an effect if the HTTP library is httpx.
*family*, an ``int``, the address family. If socket.AF_UNSPEC (the default), both A
and AAAA records will be retrieved.
Returns a ``dns.message.Message``.
"""
if not have_doh:
raise NoDOH # pragma: no cover
if session and not isinstance(session, httpx.Client):
raise ValueError("session parameter must be an httpx.Client")
wire = q.to_wire()
(af, _, the_source) = _destination_and_source(
where, port, source, source_port, False
)
transport = None
headers = {"accept": "application/dns-message"}
if af is not None and dns.inet.is_address(where):
if af == socket.AF_INET:
url = "https://{}:{}{}".format(where, port, path)
elif af == socket.AF_INET6:
url = "https://[{}]:{}{}".format(where, port, path)
else:
url = where
# set source port and source address
if the_source is None:
local_address = None
local_port = 0
else:
local_address = the_source[0]
local_port = the_source[1]
transport = _HTTPTransport(
local_address=local_address,
http1=True,
http2=True,
verify=verify,
local_port=local_port,
bootstrap_address=bootstrap_address,
resolver=resolver,
family=family,
)
if session:
cm: contextlib.AbstractContextManager = contextlib.nullcontext(session)
else:
cm = httpx.Client(http1=True, http2=True, verify=verify, transport=transport)
with cm as session:
# see https://tools.ietf.org/html/rfc8484#section-4.1.1 for DoH
# GET and POST examples
if post:
headers.update(
{
"content-type": "application/dns-message",
"content-length": str(len(wire)),
}
)
response = session.post(url, headers=headers, content=wire, timeout=timeout)
else:
wire = base64.urlsafe_b64encode(wire).rstrip(b"=")
twire = wire.decode() # httpx does a repr() if we give it bytes
response = session.get(
url, headers=headers, timeout=timeout, params={"dns": twire}
)
# see https://tools.ietf.org/html/rfc8484#section-4.2.1 for info about DoH
# status codes
if response.status_code < 200 or response.status_code > 299:
raise ValueError(
"{} responded with status code {}"
"\nResponse body: {}".format(where, response.status_code, response.content)
)
r = dns.message.from_wire(
response.content,
keyring=q.keyring,
request_mac=q.request_mac,
one_rr_per_rrset=one_rr_per_rrset,
ignore_trailing=ignore_trailing,
)
r.time = response.elapsed.total_seconds()
if not q.is_response(r):
raise BadResponse
return r
def _udp_recv(sock, max_size, expiration):
"""Reads a datagram from the socket.
A Timeout exception will be raised if the operation is not completed
by the expiration time.
"""
while True:
try:
return sock.recvfrom(max_size)
except BlockingIOError:
_wait_for_readable(sock, expiration)
def _udp_send(sock, data, destination, expiration):
"""Sends the specified datagram to destination over the socket.
A Timeout exception will be raised if the operation is not completed
by the expiration time.
"""
while True:
try:
if destination:
return sock.sendto(data, destination)
else:
return sock.send(data)
except BlockingIOError: # pragma: no cover
_wait_for_writable(sock, expiration)
def send_udp(
sock: Any,
what: Union[dns.message.Message, bytes],
destination: Any,
expiration: Optional[float] = None,
) -> Tuple[int, float]:
"""Send a DNS message to the specified UDP socket.
*sock*, a ``socket``.
*what*, a ``bytes`` or ``dns.message.Message``, the message to send.
*destination*, a destination tuple appropriate for the address family
of the socket, specifying where to send the query.
*expiration*, a ``float`` or ``None``, the absolute time at which
a timeout exception should be raised. If ``None``, no timeout will
occur.
Returns an ``(int, float)`` tuple of bytes sent and the sent time.
"""
if isinstance(what, dns.message.Message):
what = what.to_wire()
sent_time = time.time()
n = _udp_send(sock, what, destination, expiration)
return (n, sent_time)
def receive_udp(
sock: Any,
destination: Optional[Any] = None,
expiration: Optional[float] = None,
ignore_unexpected: bool = False,
one_rr_per_rrset: bool = False,
keyring: Optional[Dict[dns.name.Name, dns.tsig.Key]] = None,
request_mac: Optional[bytes] = b"",
ignore_trailing: bool = False,
raise_on_truncation: bool = False,
ignore_errors: bool = False,
query: Optional[dns.message.Message] = None,
) -> Any:
"""Read a DNS message from a UDP socket.
*sock*, a ``socket``.
*destination*, a destination tuple appropriate for the address family
of the socket, specifying where the message is expected to arrive from.
When receiving a response, this would be where the associated query was
sent.
*expiration*, a ``float`` or ``None``, the absolute time at which
a timeout exception should be raised. If ``None``, no timeout will
occur.
*ignore_unexpected*, a ``bool``. If ``True``, ignore responses from
unexpected sources.
*one_rr_per_rrset*, a ``bool``. If ``True``, put each RR into its own
RRset.
*keyring*, a ``dict``, the keyring to use for TSIG.
*request_mac*, a ``bytes`` or ``None``, the MAC of the request (for TSIG).
*ignore_trailing*, a ``bool``. If ``True``, ignore trailing
junk at end of the received message.
*raise_on_truncation*, a ``bool``. If ``True``, raise an exception if
the TC bit is set.
Raises if the message is malformed, if network errors occur, of if
there is a timeout.
If *destination* is not ``None``, returns a ``(dns.message.Message, float)``
tuple of the received message and the received time.
If *destination* is ``None``, returns a
``(dns.message.Message, float, tuple)``
tuple of the received message, the received time, and the address where
the message arrived from.
*ignore_errors*, a ``bool``. If various format errors or response
mismatches occur, ignore them and keep listening for a valid response.
The default is ``False``.
*query*, a ``dns.message.Message`` or ``None``. If not ``None`` and
*ignore_errors* is ``True``, check that the received message is a response
to this query, and if not keep listening for a valid response.
"""
wire = b""
while True:
(wire, from_address) = _udp_recv(sock, 65535, expiration)
if not _matches_destination(
sock.family, from_address, destination, ignore_unexpected
):
continue
received_time = time.time()
try:
r = dns.message.from_wire(
wire,
keyring=keyring,
request_mac=request_mac,
one_rr_per_rrset=one_rr_per_rrset,
ignore_trailing=ignore_trailing,
raise_on_truncation=raise_on_truncation,
)
except dns.message.Truncated as e:
# If we got Truncated and not FORMERR, we at least got the header with TC
# set, and very likely the question section, so we'll re-raise if the
# message seems to be a response as we need to know when truncation happens.
# We need to check that it seems to be a response as we don't want a random
# injected message with TC set to cause us to bail out.
if (
ignore_errors
and query is not None
and not query.is_response(e.message())
):
continue
else:
raise
except Exception:
if ignore_errors:
continue
else:
raise
if ignore_errors and query is not None and not query.is_response(r):
continue
if destination:
return (r, received_time)
else:
return (r, received_time, from_address)
def udp(
q: dns.message.Message,
where: str,
timeout: Optional[float] = None,
port: int = 53,
source: Optional[str] = None,
source_port: int = 0,
ignore_unexpected: bool = False,
one_rr_per_rrset: bool = False,
ignore_trailing: bool = False,
raise_on_truncation: bool = False,
sock: Optional[Any] = None,
ignore_errors: bool = False,
) -> dns.message.Message:
"""Return the response obtained after sending a query via UDP.
*q*, a ``dns.message.Message``, the query to send
*where*, a ``str`` containing an IPv4 or IPv6 address, where
to send the message.
*timeout*, a ``float`` or ``None``, the number of seconds to wait before the
query times out. If ``None``, the default, wait forever.
*port*, an ``int``, the port send the message to. The default is 53.
*source*, a ``str`` containing an IPv4 or IPv6 address, specifying
the source address. The default is the wildcard address.
*source_port*, an ``int``, the port from which to send the message.
The default is 0.
*ignore_unexpected*, a ``bool``. If ``True``, ignore responses from
unexpected sources.
*one_rr_per_rrset*, a ``bool``. If ``True``, put each RR into its own
RRset.
*ignore_trailing*, a ``bool``. If ``True``, ignore trailing
junk at end of the received message.
*raise_on_truncation*, a ``bool``. If ``True``, raise an exception if
the TC bit is set.
*sock*, a ``socket.socket``, or ``None``, the socket to use for the
query. If ``None``, the default, a socket is created. Note that
if a socket is provided, it must be a nonblocking datagram socket,
and the *source* and *source_port* are ignored.
*ignore_errors*, a ``bool``. If various format errors or response
mismatches occur, ignore them and keep listening for a valid response.
The default is ``False``.
Returns a ``dns.message.Message``.
"""
wire = q.to_wire()
(af, destination, source) = _destination_and_source(
where, port, source, source_port
)
(begin_time, expiration) = _compute_times(timeout)
if sock:
cm: contextlib.AbstractContextManager = contextlib.nullcontext(sock)
else:
cm = _make_socket(af, socket.SOCK_DGRAM, source)
with cm as s:
send_udp(s, wire, destination, expiration)
(r, received_time) = receive_udp(
s,
destination,
expiration,
ignore_unexpected,
one_rr_per_rrset,
q.keyring,
q.mac,
ignore_trailing,
raise_on_truncation,
ignore_errors,
q,
)
r.time = received_time - begin_time
# We don't need to check q.is_response() if we are in ignore_errors mode
# as receive_udp() will have checked it.
if not (ignore_errors or q.is_response(r)):
raise BadResponse
return r
assert (
False # help mypy figure out we can't get here lgtm[py/unreachable-statement]
)
def udp_with_fallback(
q: dns.message.Message,
where: str,
timeout: Optional[float] = None,
port: int = 53,
source: Optional[str] = None,
source_port: int = 0,
ignore_unexpected: bool = False,
one_rr_per_rrset: bool = False,
ignore_trailing: bool = False,
udp_sock: Optional[Any] = None,
tcp_sock: Optional[Any] = None,
ignore_errors: bool = False,
) -> Tuple[dns.message.Message, bool]:
"""Return the response to the query, trying UDP first and falling back
to TCP if UDP results in a truncated response.
*q*, a ``dns.message.Message``, the query to send
*where*, a ``str`` containing an IPv4 or IPv6 address, where to send the message.
*timeout*, a ``float`` or ``None``, the number of seconds to wait before the query
times out. If ``None``, the default, wait forever.
*port*, an ``int``, the port send the message to. The default is 53.
*source*, a ``str`` containing an IPv4 or IPv6 address, specifying the source
address. The default is the wildcard address.
*source_port*, an ``int``, the port from which to send the message. The default is
0.
*ignore_unexpected*, a ``bool``. If ``True``, ignore responses from unexpected
sources.
*one_rr_per_rrset*, a ``bool``. If ``True``, put each RR into its own RRset.
*ignore_trailing*, a ``bool``. If ``True``, ignore trailing junk at end of the
received message.
*udp_sock*, a ``socket.socket``, or ``None``, the socket to use for the UDP query.
If ``None``, the default, a socket is created. Note that if a socket is provided,
it must be a nonblocking datagram socket, and the *source* and *source_port* are
ignored for the UDP query.
*tcp_sock*, a ``socket.socket``, or ``None``, the connected socket to use for the
TCP query. If ``None``, the default, a socket is created. Note that if a socket is
provided, it must be a nonblocking connected stream socket, and *where*, *source*
and *source_port* are ignored for the TCP query.
*ignore_errors*, a ``bool``. If various format errors or response mismatches occur
while listening for UDP, ignore them and keep listening for a valid response. The
default is ``False``.
Returns a (``dns.message.Message``, tcp) tuple where tcp is ``True`` if and only if
TCP was used.
"""
try:
response = udp(
q,
where,
timeout,
port,
source,
source_port,
ignore_unexpected,
one_rr_per_rrset,
ignore_trailing,
True,
udp_sock,
ignore_errors,
)
return (response, False)
except dns.message.Truncated:
response = tcp(
q,
where,
timeout,
port,
source,
source_port,
one_rr_per_rrset,
ignore_trailing,
tcp_sock,
)
return (response, True)
def _net_read(sock, count, expiration):
"""Read the specified number of bytes from sock. Keep trying until we
either get the desired amount, or we hit EOF.
A Timeout exception will be raised if the operation is not completed
by the expiration time.
"""
s = b""
while count > 0:
try:
n = sock.recv(count)
if n == b"":
raise EOFError
count -= len(n)
s += n
except (BlockingIOError, ssl.SSLWantReadError):
_wait_for_readable(sock, expiration)
except ssl.SSLWantWriteError: # pragma: no cover
_wait_for_writable(sock, expiration)
return s
def _net_write(sock, data, expiration):
"""Write the specified data to the socket.
A Timeout exception will be raised if the operation is not completed
by the expiration time.
"""
current = 0
l = len(data)
while current < l:
try:
current += sock.send(data[current:])
except (BlockingIOError, ssl.SSLWantWriteError):
_wait_for_writable(sock, expiration)
except ssl.SSLWantReadError: # pragma: no cover
_wait_for_readable(sock, expiration)
def send_tcp(
sock: Any,
what: Union[dns.message.Message, bytes],
expiration: Optional[float] = None,
) -> Tuple[int, float]:
"""Send a DNS message to the specified TCP socket.
*sock*, a ``socket``.
*what*, a ``bytes`` or ``dns.message.Message``, the message to send.
*expiration*, a ``float`` or ``None``, the absolute time at which
a timeout exception should be raised. If ``None``, no timeout will
occur.
Returns an ``(int, float)`` tuple of bytes sent and the sent time.
"""
if isinstance(what, dns.message.Message):
tcpmsg = what.to_wire(prepend_length=True)
else:
# copying the wire into tcpmsg is inefficient, but lets us
# avoid writev() or doing a short write that would get pushed
# onto the net
tcpmsg = len(what).to_bytes(2, "big") + what
sent_time = time.time()
_net_write(sock, tcpmsg, expiration)
return (len(tcpmsg), sent_time)
def receive_tcp(
sock: Any,
expiration: Optional[float] = None,
one_rr_per_rrset: bool = False,
keyring: Optional[Dict[dns.name.Name, dns.tsig.Key]] = None,
request_mac: Optional[bytes] = b"",
ignore_trailing: bool = False,
) -> Tuple[dns.message.Message, float]:
"""Read a DNS message from a TCP socket.
*sock*, a ``socket``.
*expiration*, a ``float`` or ``None``, the absolute time at which
a timeout exception should be raised. If ``None``, no timeout will
occur.
*one_rr_per_rrset*, a ``bool``. If ``True``, put each RR into its own
RRset.
*keyring*, a ``dict``, the keyring to use for TSIG.
*request_mac*, a ``bytes`` or ``None``, the MAC of the request (for TSIG).
*ignore_trailing*, a ``bool``. If ``True``, ignore trailing
junk at end of the received message.
Raises if the message is malformed, if network errors occur, of if
there is a timeout.
Returns a ``(dns.message.Message, float)`` tuple of the received message
and the received time.
"""
ldata = _net_read(sock, 2, expiration)
(l,) = struct.unpack("!H", ldata)
wire = _net_read(sock, l, expiration)
received_time = time.time()
r = dns.message.from_wire(
wire,
keyring=keyring,
request_mac=request_mac,
one_rr_per_rrset=one_rr_per_rrset,
ignore_trailing=ignore_trailing,
)
return (r, received_time)
def _connect(s, address, expiration):
err = s.connect_ex(address)
if err == 0:
return
if err in (errno.EINPROGRESS, errno.EWOULDBLOCK, errno.EALREADY):
_wait_for_writable(s, expiration)
err = s.getsockopt(socket.SOL_SOCKET, socket.SO_ERROR)
if err != 0:
raise OSError(err, os.strerror(err))
def tcp(
q: dns.message.Message,
where: str,
timeout: Optional[float] = None,
port: int = 53,
source: Optional[str] = None,
source_port: int = 0,
one_rr_per_rrset: bool = False,
ignore_trailing: bool = False,
sock: Optional[Any] = None,
) -> dns.message.Message:
"""Return the response obtained after sending a query via TCP.
*q*, a ``dns.message.Message``, the query to send
*where*, a ``str`` containing an IPv4 or IPv6 address, where
to send the message.
*timeout*, a ``float`` or ``None``, the number of seconds to wait before the
query times out. If ``None``, the default, wait forever.
*port*, an ``int``, the port send the message to. The default is 53.
*source*, a ``str`` containing an IPv4 or IPv6 address, specifying
the source address. The default is the wildcard address.
*source_port*, an ``int``, the port from which to send the message.
The default is 0.
*one_rr_per_rrset*, a ``bool``. If ``True``, put each RR into its own
RRset.
*ignore_trailing*, a ``bool``. If ``True``, ignore trailing
junk at end of the received message.
*sock*, a ``socket.socket``, or ``None``, the connected socket to use for the
query. If ``None``, the default, a socket is created. Note that
if a socket is provided, it must be a nonblocking connected stream
socket, and *where*, *port*, *source* and *source_port* are ignored.
Returns a ``dns.message.Message``.
"""
wire = q.to_wire()
(begin_time, expiration) = _compute_times(timeout)
if sock:
cm: contextlib.AbstractContextManager = contextlib.nullcontext(sock)
else:
(af, destination, source) = _destination_and_source(
where, port, source, source_port
)
cm = _make_socket(af, socket.SOCK_STREAM, source)
with cm as s:
if not sock:
_connect(s, destination, expiration)
send_tcp(s, wire, expiration)
(r, received_time) = receive_tcp(
s, expiration, one_rr_per_rrset, q.keyring, q.mac, ignore_trailing
)
r.time = received_time - begin_time
if not q.is_response(r):
raise BadResponse
return r
assert (
False # help mypy figure out we can't get here lgtm[py/unreachable-statement]
)
def _tls_handshake(s, expiration):
while True:
try:
s.do_handshake()
return
except ssl.SSLWantReadError:
_wait_for_readable(s, expiration)
except ssl.SSLWantWriteError: # pragma: no cover
_wait_for_writable(s, expiration)
def _make_dot_ssl_context(
server_hostname: Optional[str], verify: Union[bool, str]
) -> ssl.SSLContext:
cafile: Optional[str] = None
capath: Optional[str] = None
if isinstance(verify, str):
if os.path.isfile(verify):
cafile = verify
elif os.path.isdir(verify):
capath = verify
else:
raise ValueError("invalid verify string")
ssl_context = ssl.create_default_context(cafile=cafile, capath=capath)
ssl_context.minimum_version = ssl.TLSVersion.TLSv1_2
if server_hostname is None:
ssl_context.check_hostname = False
ssl_context.set_alpn_protocols(["dot"])
if verify is False:
ssl_context.verify_mode = ssl.CERT_NONE
return ssl_context
def tls(
q: dns.message.Message,
where: str,
timeout: Optional[float] = None,
port: int = 853,
source: Optional[str] = None,
source_port: int = 0,
one_rr_per_rrset: bool = False,
ignore_trailing: bool = False,
sock: Optional[ssl.SSLSocket] = None,
ssl_context: Optional[ssl.SSLContext] = None,
server_hostname: Optional[str] = None,
verify: Union[bool, str] = True,
) -> dns.message.Message:
"""Return the response obtained after sending a query via TLS.
*q*, a ``dns.message.Message``, the query to send
*where*, a ``str`` containing an IPv4 or IPv6 address, where
to send the message.
*timeout*, a ``float`` or ``None``, the number of seconds to wait before the
query times out. If ``None``, the default, wait forever.
*port*, an ``int``, the port send the message to. The default is 853.
*source*, a ``str`` containing an IPv4 or IPv6 address, specifying
the source address. The default is the wildcard address.
*source_port*, an ``int``, the port from which to send the message.
The default is 0.
*one_rr_per_rrset*, a ``bool``. If ``True``, put each RR into its own
RRset.
*ignore_trailing*, a ``bool``. If ``True``, ignore trailing
junk at end of the received message.
*sock*, an ``ssl.SSLSocket``, or ``None``, the socket to use for
the query. If ``None``, the default, a socket is created. Note
that if a socket is provided, it must be a nonblocking connected
SSL stream socket, and *where*, *port*, *source*, *source_port*,
and *ssl_context* are ignored.
*ssl_context*, an ``ssl.SSLContext``, the context to use when establishing
a TLS connection. If ``None``, the default, creates one with the default
configuration.
*server_hostname*, a ``str`` containing the server's hostname. The
default is ``None``, which means that no hostname is known, and if an
SSL context is created, hostname checking will be disabled.
*verify*, a ``bool`` or ``str``. If a ``True``, then TLS certificate verification
of the server is done using the default CA bundle; if ``False``, then no
verification is done; if a `str` then it specifies the path to a certificate file or
directory which will be used for verification.
Returns a ``dns.message.Message``.
"""
if sock:
#
# If a socket was provided, there's no special TLS handling needed.
#
return tcp(
q,
where,
timeout,
port,
source,
source_port,
one_rr_per_rrset,
ignore_trailing,
sock,
)
wire = q.to_wire()
(begin_time, expiration) = _compute_times(timeout)
(af, destination, source) = _destination_and_source(
where, port, source, source_port
)
if ssl_context is None and not sock:
ssl_context = _make_dot_ssl_context(server_hostname, verify)
with _make_socket(
af,
socket.SOCK_STREAM,
source,
ssl_context=ssl_context,
server_hostname=server_hostname,
) as s:
_connect(s, destination, expiration)
_tls_handshake(s, expiration)
send_tcp(s, wire, expiration)
(r, received_time) = receive_tcp(
s, expiration, one_rr_per_rrset, q.keyring, q.mac, ignore_trailing
)
r.time = received_time - begin_time
if not q.is_response(r):
raise BadResponse
return r
assert (
False # help mypy figure out we can't get here lgtm[py/unreachable-statement]
)
def quic(
q: dns.message.Message,
where: str,
timeout: Optional[float] = None,
port: int = 853,
source: Optional[str] = None,
source_port: int = 0,
one_rr_per_rrset: bool = False,
ignore_trailing: bool = False,
connection: Optional[dns.quic.SyncQuicConnection] = None,
verify: Union[bool, str] = True,
server_hostname: Optional[str] = None,
) -> dns.message.Message:
"""Return the response obtained after sending a query via DNS-over-QUIC.
*q*, a ``dns.message.Message``, the query to send.
*where*, a ``str``, the nameserver IP address.
*timeout*, a ``float`` or ``None``, the number of seconds to wait before the query
times out. If ``None``, the default, wait forever.
*port*, a ``int``, the port to send the query to. The default is 853.
*source*, a ``str`` containing an IPv4 or IPv6 address, specifying the source
address. The default is the wildcard address.
*source_port*, an ``int``, the port from which to send the message. The default is
0.
*one_rr_per_rrset*, a ``bool``. If ``True``, put each RR into its own RRset.
*ignore_trailing*, a ``bool``. If ``True``, ignore trailing junk at end of the
received message.
*connection*, a ``dns.quic.SyncQuicConnection``. If provided, the
connection to use to send the query.
*verify*, a ``bool`` or ``str``. If a ``True``, then TLS certificate verification
of the server is done using the default CA bundle; if ``False``, then no
verification is done; if a `str` then it specifies the path to a certificate file or
directory which will be used for verification.
*server_hostname*, a ``str`` containing the server's hostname. The
default is ``None``, which means that no hostname is known, and if an
SSL context is created, hostname checking will be disabled.
Returns a ``dns.message.Message``.
"""
if not dns.quic.have_quic:
raise NoDOQ("DNS-over-QUIC is not available.") # pragma: no cover
q.id = 0
wire = q.to_wire()
the_connection: dns.quic.SyncQuicConnection
the_manager: dns.quic.SyncQuicManager
if connection:
manager: contextlib.AbstractContextManager = contextlib.nullcontext(None)
the_connection = connection
else:
manager = dns.quic.SyncQuicManager(
verify_mode=verify, server_name=server_hostname
)
the_manager = manager # for type checking happiness
with manager:
if not connection:
the_connection = the_manager.connect(where, port, source, source_port)
(start, expiration) = _compute_times(timeout)
with the_connection.make_stream(timeout) as stream:
stream.send(wire, True)
wire = stream.receive(_remaining(expiration))
finish = time.time()
r = dns.message.from_wire(
wire,
keyring=q.keyring,
request_mac=q.request_mac,
one_rr_per_rrset=one_rr_per_rrset,
ignore_trailing=ignore_trailing,
)
r.time = max(finish - start, 0.0)
if not q.is_response(r):
raise BadResponse
return r
def xfr(
where: str,
zone: Union[dns.name.Name, str],
rdtype: Union[dns.rdatatype.RdataType, str] = dns.rdatatype.AXFR,
rdclass: Union[dns.rdataclass.RdataClass, str] = dns.rdataclass.IN,
timeout: Optional[float] = None,
port: int = 53,
keyring: Optional[Dict[dns.name.Name, dns.tsig.Key]] = None,
keyname: Optional[Union[dns.name.Name, str]] = None,
relativize: bool = True,
lifetime: Optional[float] = None,
source: Optional[str] = None,
source_port: int = 0,
serial: int = 0,
use_udp: bool = False,
keyalgorithm: Union[dns.name.Name, str] = dns.tsig.default_algorithm,
) -> Any:
"""Return a generator for the responses to a zone transfer.
*where*, a ``str`` containing an IPv4 or IPv6 address, where
to send the message.
*zone*, a ``dns.name.Name`` or ``str``, the name of the zone to transfer.
*rdtype*, an ``int`` or ``str``, the type of zone transfer. The
default is ``dns.rdatatype.AXFR``. ``dns.rdatatype.IXFR`` can be
used to do an incremental transfer instead.
*rdclass*, an ``int`` or ``str``, the class of the zone transfer.
The default is ``dns.rdataclass.IN``.
*timeout*, a ``float``, the number of seconds to wait for each
response message. If None, the default, wait forever.
*port*, an ``int``, the port send the message to. The default is 53.
*keyring*, a ``dict``, the keyring to use for TSIG.
*keyname*, a ``dns.name.Name`` or ``str``, the name of the TSIG
key to use.
*relativize*, a ``bool``. If ``True``, all names in the zone will be
relativized to the zone origin. It is essential that the
relativize setting matches the one specified to
``dns.zone.from_xfr()`` if using this generator to make a zone.
*lifetime*, a ``float``, the total number of seconds to spend
doing the transfer. If ``None``, the default, then there is no
limit on the time the transfer may take.
*source*, a ``str`` containing an IPv4 or IPv6 address, specifying
the source address. The default is the wildcard address.
*source_port*, an ``int``, the port from which to send the message.
The default is 0.
*serial*, an ``int``, the SOA serial number to use as the base for
an IXFR diff sequence (only meaningful if *rdtype* is
``dns.rdatatype.IXFR``).
*use_udp*, a ``bool``. If ``True``, use UDP (only meaningful for IXFR).
*keyalgorithm*, a ``dns.name.Name`` or ``str``, the TSIG algorithm to use.
Raises on errors, and so does the generator.
Returns a generator of ``dns.message.Message`` objects.
"""
if isinstance(zone, str):
zone = dns.name.from_text(zone)
rdtype = dns.rdatatype.RdataType.make(rdtype)
q = dns.message.make_query(zone, rdtype, rdclass)
if rdtype == dns.rdatatype.IXFR:
rrset = dns.rrset.from_text(zone, 0, "IN", "SOA", ". . %u 0 0 0 0" % serial)
q.authority.append(rrset)
if keyring is not None:
q.use_tsig(keyring, keyname, algorithm=keyalgorithm)
wire = q.to_wire()
(af, destination, source) = _destination_and_source(
where, port, source, source_port
)
if use_udp and rdtype != dns.rdatatype.IXFR:
raise ValueError("cannot do a UDP AXFR")
sock_type = socket.SOCK_DGRAM if use_udp else socket.SOCK_STREAM
with _make_socket(af, sock_type, source) as s:
(_, expiration) = _compute_times(lifetime)
_connect(s, destination, expiration)
l = len(wire)
if use_udp:
_udp_send(s, wire, None, expiration)
else:
tcpmsg = struct.pack("!H", l) + wire
_net_write(s, tcpmsg, expiration)
done = False
delete_mode = True
expecting_SOA = False
soa_rrset = None
if relativize:
origin = zone
oname = dns.name.empty
else:
origin = None
oname = zone
tsig_ctx = None
while not done:
(_, mexpiration) = _compute_times(timeout)
if mexpiration is None or (
expiration is not None and mexpiration > expiration
):
mexpiration = expiration
if use_udp:
(wire, _) = _udp_recv(s, 65535, mexpiration)
else:
ldata = _net_read(s, 2, mexpiration)
(l,) = struct.unpack("!H", ldata)
wire = _net_read(s, l, mexpiration)
is_ixfr = rdtype == dns.rdatatype.IXFR
r = dns.message.from_wire(
wire,
keyring=q.keyring,
request_mac=q.mac,
xfr=True,
origin=origin,
tsig_ctx=tsig_ctx,
multi=True,
one_rr_per_rrset=is_ixfr,
)
rcode = r.rcode()
if rcode != dns.rcode.NOERROR:
raise TransferError(rcode)
tsig_ctx = r.tsig_ctx
answer_index = 0
if soa_rrset is None:
if not r.answer or r.answer[0].name != oname:
raise dns.exception.FormError("No answer or RRset not for qname")
rrset = r.answer[0]
if rrset.rdtype != dns.rdatatype.SOA:
raise dns.exception.FormError("first RRset is not an SOA")
answer_index = 1
soa_rrset = rrset.copy()
if rdtype == dns.rdatatype.IXFR:
if dns.serial.Serial(soa_rrset[0].serial) <= serial:
#
# We're already up-to-date.
#
done = True
else:
expecting_SOA = True
#
# Process SOAs in the answer section (other than the initial
# SOA in the first message).
#
for rrset in r.answer[answer_index:]:
if done:
raise dns.exception.FormError("answers after final SOA")
if rrset.rdtype == dns.rdatatype.SOA and rrset.name == oname:
if expecting_SOA:
if rrset[0].serial != serial:
raise dns.exception.FormError("IXFR base serial mismatch")
expecting_SOA = False
elif rdtype == dns.rdatatype.IXFR:
delete_mode = not delete_mode
#
# If this SOA RRset is equal to the first we saw then we're
# finished. If this is an IXFR we also check that we're
# seeing the record in the expected part of the response.
#
if rrset == soa_rrset and (
rdtype == dns.rdatatype.AXFR
or (rdtype == dns.rdatatype.IXFR and delete_mode)
):
done = True
elif expecting_SOA:
#
# We made an IXFR request and are expecting another
# SOA RR, but saw something else, so this must be an
# AXFR response.
#
rdtype = dns.rdatatype.AXFR
expecting_SOA = False
if done and q.keyring and not r.had_tsig:
raise dns.exception.FormError("missing TSIG")
yield r
class UDPMode(enum.IntEnum):
"""How should UDP be used in an IXFR from :py:func:`inbound_xfr()`?
NEVER means "never use UDP; always use TCP"
TRY_FIRST means "try to use UDP but fall back to TCP if needed"
ONLY means "raise ``dns.xfr.UseTCP`` if trying UDP does not succeed"
"""
NEVER = 0
TRY_FIRST = 1
ONLY = 2
def inbound_xfr(
where: str,
txn_manager: dns.transaction.TransactionManager,
query: Optional[dns.message.Message] = None,
port: int = 53,
timeout: Optional[float] = None,
lifetime: Optional[float] = None,
source: Optional[str] = None,
source_port: int = 0,
udp_mode: UDPMode = UDPMode.NEVER,
) -> None:
"""Conduct an inbound transfer and apply it via a transaction from the
txn_manager.
*where*, a ``str`` containing an IPv4 or IPv6 address, where
to send the message.
*txn_manager*, a ``dns.transaction.TransactionManager``, the txn_manager
for this transfer (typically a ``dns.zone.Zone``).
*query*, the query to send. If not supplied, a default query is
constructed using information from the *txn_manager*.
*port*, an ``int``, the port send the message to. The default is 53.
*timeout*, a ``float``, the number of seconds to wait for each
response message. If None, the default, wait forever.
*lifetime*, a ``float``, the total number of seconds to spend
doing the transfer. If ``None``, the default, then there is no
limit on the time the transfer may take.
*source*, a ``str`` containing an IPv4 or IPv6 address, specifying
the source address. The default is the wildcard address.
*source_port*, an ``int``, the port from which to send the message.
The default is 0.
*udp_mode*, a ``dns.query.UDPMode``, determines how UDP is used
for IXFRs. The default is ``dns.UDPMode.NEVER``, i.e. only use
TCP. Other possibilities are ``dns.UDPMode.TRY_FIRST``, which
means "try UDP but fallback to TCP if needed", and
``dns.UDPMode.ONLY``, which means "try UDP and raise
``dns.xfr.UseTCP`` if it does not succeed.
Raises on errors.
"""
if query is None:
(query, serial) = dns.xfr.make_query(txn_manager)
else:
serial = dns.xfr.extract_serial_from_query(query)
rdtype = query.question[0].rdtype
is_ixfr = rdtype == dns.rdatatype.IXFR
origin = txn_manager.from_wire_origin()
wire = query.to_wire()
(af, destination, source) = _destination_and_source(
where, port, source, source_port
)
(_, expiration) = _compute_times(lifetime)
retry = True
while retry:
retry = False
if is_ixfr and udp_mode != UDPMode.NEVER:
sock_type = socket.SOCK_DGRAM
is_udp = True
else:
sock_type = socket.SOCK_STREAM
is_udp = False
with _make_socket(af, sock_type, source) as s:
_connect(s, destination, expiration)
if is_udp:
_udp_send(s, wire, None, expiration)
else:
tcpmsg = struct.pack("!H", len(wire)) + wire
_net_write(s, tcpmsg, expiration)
with dns.xfr.Inbound(txn_manager, rdtype, serial, is_udp) as inbound:
done = False
tsig_ctx = None
while not done:
(_, mexpiration) = _compute_times(timeout)
if mexpiration is None or (
expiration is not None and mexpiration > expiration
):
mexpiration = expiration
if is_udp:
(rwire, _) = _udp_recv(s, 65535, mexpiration)
else:
ldata = _net_read(s, 2, mexpiration)
(l,) = struct.unpack("!H", ldata)
rwire = _net_read(s, l, mexpiration)
r = dns.message.from_wire(
rwire,
keyring=query.keyring,
request_mac=query.mac,
xfr=True,
origin=origin,
tsig_ctx=tsig_ctx,
multi=(not is_udp),
one_rr_per_rrset=is_ixfr,
)
try:
done = inbound.process_message(r)
except dns.xfr.UseTCP:
assert is_udp # should not happen if we used TCP!
if udp_mode == UDPMode.ONLY:
raise
done = True
retry = True
udp_mode = UDPMode.NEVER
continue
tsig_ctx = r.tsig_ctx
if not retry and query.keyring and not r.had_tsig:
raise dns.exception.FormError("missing TSIG")