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#!/usr/bin/python3
# Copyright (C) Internet Systems Consortium, Inc. ("ISC")
#
# SPDX-License-Identifier: MPL-2.0
#
# This Source Code Form is subject to the terms of the Mozilla Public
# License, v. 2.0. If a copy of the MPL was not distributed with this
# file, you can obtain one at https://mozilla.org/MPL/2.0/.
#
# See the COPYRIGHT file distributed with this work for additional
# information regarding copyright ownership.
# pylint: disable=unused-variable
import socket
import time
import pytest
pytest.importorskip("dns", minversion="2.0.0")
import dns.message
import dns.query
TIMEOUT = 10
def create_msg(qname, qtype, edns=-1):
msg = dns.message.make_query(qname, qtype, use_edns=edns)
return msg
def timeout():
return time.time() + TIMEOUT
def create_socket(host, port):
sock = socket.create_connection((host, port), timeout=10)
sock.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY, True)
return sock
# Regression test for CVE-2022-0396
def test_close_wait(named_port):
with create_socket("10.53.0.7", named_port) as sock:
msg = create_msg("a.example.", "A")
(sbytes, stime) = dns.query.send_tcp(sock, msg, timeout())
(response, rtime) = dns.query.receive_tcp(sock, timeout())
msg = dns.message.make_query("a.example.", "A", use_edns=0, payload=1232)
(sbytes, stime) = dns.query.send_tcp(sock, msg, timeout())
# Shutdown the socket, but ignore the other side closing the socket
# first because we sent DNS message with EDNS0
try:
sock.shutdown(socket.SHUT_RDWR)
except ConnectionError:
pass
except OSError:
pass
# BIND allows one TCP client, the part above sends DNS messaage with EDNS0
# after the first query. BIND should react adequately because of
# ns7/named.dropedns and close the socket, making room for the next
# request. If it gets stuck in CLOSE_WAIT state, there is no connection
# available for the query below and it will time out.
with create_socket("10.53.0.7", named_port) as sock:
msg = create_msg("a.example.", "A")
(sbytes, stime) = dns.query.send_tcp(sock, msg, timeout())
(response, rtime) = dns.query.receive_tcp(sock, timeout())
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