bazarr/libs/dns/query.py

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# Copyright (C) Dnspython Contributors, see LICENSE for text of ISC license
# Copyright (C) 2003-2017 Nominum, Inc.
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#
# 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 contextlib
import enum
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import errno
import os
import selectors
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import socket
import struct
import time
import base64
import urllib.parse
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import dns.exception
import dns.inet
import dns.name
import dns.message
import dns.rcode
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import dns.rdataclass
import dns.rdatatype
import dns.serial
import dns.xfr
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try:
import requests
from requests_toolbelt.adapters.source import SourceAddressAdapter
from requests_toolbelt.adapters.host_header_ssl import HostHeaderSSLAdapter
_have_requests = True
except ImportError: # pragma: no cover
_have_requests = False
_have_httpx = False
_have_http2 = False
try:
import httpx
_have_httpx = True
try:
# See if http2 support is available.
with httpx.Client(http2=True):
_have_http2 = True
except Exception:
pass
except ImportError: # pragma: no cover
pass
have_doh = _have_requests or _have_httpx
try:
import ssl
except ImportError: # pragma: no cover
class ssl: # type: ignore
class WantReadException(Exception):
pass
class WantWriteException(Exception):
pass
class SSLSocket:
pass
def create_default_context(self, *args, **kwargs):
raise Exception('no ssl support')
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# 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 requests module is not
available."""
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# for backwards compatibility
TransferError = dns.xfr.TransferError
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def _compute_times(timeout):
now = time.time()
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if timeout is None:
return (now, None)
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else:
return (now, now + timeout)
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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.
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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
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def _set_selector_class(selector_class):
# Internal API. Do not use.
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global _selector_class
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_selector_class = selector_class
if hasattr(selectors, 'PollSelector'):
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# 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).
_selector_class = selectors.PollSelector
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else:
_selector_class = selectors.SelectSelector # pragma: no cover
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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
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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):
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# 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.
if af == socket.AF_INET:
source = '0.0.0.0'
elif af == socket.AF_INET6:
source = '::'
else:
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)
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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:
return ssl_context.wrap_socket(s, do_handshake_on_connect=False,
server_hostname=server_hostname)
else:
return s
except Exception:
s.close()
raise
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def https(q, where, timeout=None, port=443, source=None, source_port=0,
one_rr_per_rrset=False, ignore_trailing=False,
session=None, path='/dns-query', post=True,
bootstrap_address=None, verify=True):
"""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.
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*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.
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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`` or ``requests.session.Session``. 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 the
system's DNS resolver.
*verify*, a ``str``, containing a path to a certificate file or directory.
Returns a ``dns.message.Message``.
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"""
if not have_doh:
raise NoDOH('Neither httpx nor requests is available.') # pragma: no cover
_httpx_ok = _have_httpx
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wire = q.to_wire()
(af, _, source) = _destination_and_source(where, port, source, source_port,
False)
transport_adapter = None
transport = None
headers = {
"accept": "application/dns-message"
}
if af is not None:
if af == socket.AF_INET:
url = 'https://{}:{}{}'.format(where, port, path)
elif af == socket.AF_INET6:
url = 'https://[{}]:{}{}'.format(where, port, path)
elif bootstrap_address is not None:
_httpx_ok = False
split_url = urllib.parse.urlsplit(where)
headers['Host'] = split_url.hostname
url = where.replace(split_url.hostname, bootstrap_address)
if _have_requests:
transport_adapter = HostHeaderSSLAdapter()
else:
url = where
if source is not None:
# set source port and source address
if _have_httpx:
if source_port == 0:
transport = httpx.HTTPTransport(local_address=source[0])
else:
_httpx_ok = False
if _have_requests:
transport_adapter = SourceAddressAdapter(source)
if session:
if _have_httpx:
_is_httpx = isinstance(session, httpx.Client)
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else:
_is_httpx = False
if _is_httpx and not _httpx_ok:
raise NoDOH('Session is httpx, but httpx cannot be used for '
'the requested operation.')
else:
_is_httpx = _httpx_ok
if not _httpx_ok and not _have_requests:
raise NoDOH('Cannot use httpx for this operation, and '
'requests is not available.')
with contextlib.ExitStack() as stack:
if not session:
if _is_httpx:
session = stack.enter_context(httpx.Client(http1=True,
http2=_have_http2,
verify=verify,
transport=transport))
else:
session = stack.enter_context(requests.sessions.Session())
if transport_adapter:
session.mount(url, transport_adapter)
# 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))
})
if _is_httpx:
response = session.post(url, headers=headers, content=wire,
timeout=timeout)
else:
response = session.post(url, headers=headers, data=wire,
timeout=timeout, verify=verify)
else:
wire = base64.urlsafe_b64encode(wire).rstrip(b"=")
if _is_httpx:
wire = wire.decode() # httpx does a repr() if we give it bytes
response = session.get(url, headers=headers,
timeout=timeout,
params={"dns": wire})
else:
response = session.get(url, headers=headers,
timeout=timeout, verify=verify,
params={"dns": wire})
# 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
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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, what, destination, expiration=None):
"""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, destination=None, expiration=None,
ignore_unexpected=False, one_rr_per_rrset=False,
keyring=None, request_mac=b'', ignore_trailing=False,
raise_on_truncation=False):
"""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``, 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.
"""
wire = b''
while True:
(wire, from_address) = _udp_recv(sock, 65535, expiration)
if _matches_destination(sock.family, from_address, destination,
ignore_unexpected):
break
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,
raise_on_truncation=raise_on_truncation)
if destination:
return (r, received_time)
else:
return (r, received_time, from_address)
def udp(q, where, timeout=None, port=53, source=None, source_port=0,
ignore_unexpected=False, one_rr_per_rrset=False, ignore_trailing=False,
raise_on_truncation=False, sock=None):
"""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.
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)
with contextlib.ExitStack() as stack:
if sock:
s = sock
else:
s = stack.enter_context(_make_socket(af, socket.SOCK_DGRAM, source))
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)
r.time = received_time - begin_time
if not q.is_response(r):
raise BadResponse
return r
def udp_with_fallback(q, where, timeout=None, port=53, source=None,
source_port=0, ignore_unexpected=False,
one_rr_per_rrset=False, ignore_trailing=False,
udp_sock=None, tcp_sock=None):
"""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.
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)
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)
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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)
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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)
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def send_tcp(sock, what, expiration=None):
"""Send a DNS message to the specified TCP socket.
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*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):
what = what.to_wire()
l = len(what)
# 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 = struct.pack("!H", l) + what
sent_time = time.time()
_net_write(sock, tcpmsg, expiration)
return (len(tcpmsg), sent_time)
def receive_tcp(sock, expiration=None, one_rr_per_rrset=False,
keyring=None, request_mac=b'', ignore_trailing=False):
"""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``, 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)
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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))
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def tcp(q, where, timeout=None, port=53, source=None, source_port=0,
one_rr_per_rrset=False, ignore_trailing=False, sock=None):
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"""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.
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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``.
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"""
wire = q.to_wire()
(begin_time, expiration) = _compute_times(timeout)
with contextlib.ExitStack() as stack:
if sock:
s = sock
else:
(af, destination, source) = _destination_and_source(where, port,
source,
source_port)
s = stack.enter_context(_make_socket(af, socket.SOCK_STREAM,
source))
_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
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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 tls(q, where, timeout=None, port=853, source=None, source_port=0,
one_rr_per_rrset=False, ignore_trailing=False, sock=None,
ssl_context=None, server_hostname=None):
"""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.
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 = ssl.create_default_context()
if server_hostname is None:
ssl_context.check_hostname = False
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
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def xfr(where, zone, rdtype=dns.rdatatype.AXFR, rdclass=dns.rdataclass.IN,
timeout=None, port=53, keyring=None, keyname=None, relativize=True,
lifetime=None, source=None, source_port=0, serial=0,
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use_udp=False, keyalgorithm=dns.tsig.default_algorithm):
"""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.
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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.
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"""
if isinstance(zone, str):
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zone = dns.name.from_text(zone)
rdtype = dns.rdatatype.RdataType.make(rdtype)
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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,
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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)
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if use_udp:
_udp_send(s, wire, None, expiration)
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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
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#
# 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.
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#
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
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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, txn_manager, query=None,
port=53, timeout=None, lifetime=None, source=None,
source_port=0, udp_mode=UDPMode.NEVER):
"""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 possibilites 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 succeeed.
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")