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https://gitlab.isc.org/isc-projects/bind9
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b9ebde705b
Add a test case to check for lingering TCP sockets stuck in the CLOSE_WAIT state. This can happen if a client sends some garbage after its first query. The system test runs the reproducer script and then sends another TCP query to the resolver. The resolver is configured to allow one TCP client only. If BIND has its TCP socket stuck in CLOSE_WAIT, it does not have the resources available to answer the second query. Note: A better test would be to check if the named daemon does not have a TCP socket stuck in CLOSE_WAIT for example with netstat. When running this test locally you can examine named with netstat manually. But since netstat is platform specific it is not a good candidate to do this as a system test. If you, if you could return, don't let it burn. Do you have to let it linger? - Cranberries
122 lines
3.8 KiB
Python
122 lines
3.8 KiB
Python
#!/usr/bin/python3
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# Copyright (C) Internet Systems Consortium, Inc. ("ISC")
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#
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# SPDX-License-Identifier: MPL-2.0
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#
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# This Source Code Form is subject to the terms of the Mozilla Public
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# License, v. 2.0. If a copy of the MPL was not distributed with this
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# file, you can obtain one at https://mozilla.org/MPL/2.0/.
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#
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# See the COPYRIGHT file distributed with this work for additional
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# information regarding copyright ownership.
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# pylint: disable=unused-variable
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import socket
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import struct
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import time
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import pytest
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pytest.importorskip('dns', minversion='2.0.0')
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import dns.message
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import dns.query
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TIMEOUT = 10
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def create_msg(qname, qtype, edns=-1):
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msg = dns.message.make_query(qname, qtype, use_edns=edns)
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return msg
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def timeout():
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return time.time() + TIMEOUT
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def create_socket(host, port):
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sock = socket.create_connection((host, port), timeout=1)
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sock.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY, True)
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return sock
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def test_tcp_garbage(named_port):
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with create_socket("10.53.0.7", named_port) as sock:
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msg = create_msg("a.example.", "A")
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(sbytes, stime) = dns.query.send_tcp(sock, msg, timeout())
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(response, rtime) = dns.query.receive_tcp(sock, timeout())
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wire = msg.to_wire()
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assert len(wire) > 0
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# Send DNS message shorter than DNS message header (12),
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# this should cause the connection to be terminated
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sock.send(struct.pack('!H', 11))
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sock.send(struct.pack('!s', b'0123456789a'))
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with pytest.raises(EOFError):
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try:
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(sbytes, stime) = dns.query.send_tcp(sock, msg, timeout())
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(response, rtime) = dns.query.receive_tcp(sock, timeout())
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except ConnectionError as e:
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raise EOFError from e
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def test_tcp_garbage_response(named_port):
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with create_socket("10.53.0.7", named_port) as sock:
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msg = create_msg("a.example.", "A")
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(sbytes, stime) = dns.query.send_tcp(sock, msg, timeout())
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(response, rtime) = dns.query.receive_tcp(sock, timeout())
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wire = msg.to_wire()
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assert len(wire) > 0
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# Send DNS response instead of DNS query, this should cause
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# the connection to be terminated
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rmsg = dns.message.make_response(msg)
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(sbytes, stime) = dns.query.send_tcp(sock, rmsg, timeout())
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with pytest.raises(EOFError):
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try:
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(response, rtime) = dns.query.receive_tcp(sock, timeout())
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except ConnectionError as e:
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raise EOFError from e
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# Regression test for CVE-2022-0396
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def test_close_wait(named_port):
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with create_socket("10.53.0.7", named_port) as sock:
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msg = create_msg("a.example.", "A")
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(sbytes, stime) = dns.query.send_tcp(sock, msg, timeout())
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(response, rtime) = dns.query.receive_tcp(sock, timeout())
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msg = dns.message.make_query("a.example.", "A", use_edns=0,
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payload=1232)
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(sbytes, stime) = dns.query.send_tcp(sock, msg, timeout())
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# Shutdown the socket, but ignore the other side closing the socket
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# first because we sent DNS message with EDNS0
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try:
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sock.shutdown(socket.SHUT_RDWR)
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except ConnectionError:
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pass
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except OSError:
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pass
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# BIND allows one TCP client, the part above sends DNS messaage with EDNS0
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# after the first query. BIND should react adequately because of
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# ns7/named.dropedns and close the socket, making room for the next
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# request. If it gets stuck in CLOSE_WAIT state, there is no connection
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# available for the query below and it will time out.
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with create_socket("10.53.0.7", named_port) as sock:
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msg = create_msg("a.example.", "A")
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(sbytes, stime) = dns.query.send_tcp(sock, msg, timeout())
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(response, rtime) = dns.query.receive_tcp(sock, timeout())
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