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[3.8] gh-108342: Make ssl TestPreHandshakeClose more reliable (GH-108370
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) (#108408)

* In preauth tests of test_ssl, explicitly break reference cycles
  invoving SingleConnectionTestServerThread to make sure that the
  thread is deleted. Otherwise, the test marks the environment as
  altered because the threading module sees a "dangling thread"
  (SingleConnectionTestServerThread). This test leak was introduced
  by the test added for the fix of issue gh-108310.
* Use support.SHORT_TIMEOUT instead of hardcoded 1.0 or 2.0 seconds
  timeout.
* SingleConnectionTestServerThread.run() catchs TimeoutError
* Fix a race condition (missing synchronization) in
  test_preauth_data_to_tls_client(): the server now waits until the
  client connect() completed in call_after_accept().
* test_https_client_non_tls_response_ignored() calls server.join()
  explicitly.
* Replace "localhost" with server.listener.getsockname()[0].
(cherry picked from commit 592bacb)
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@ambv
ambv authored Aug 24, 2023
1 parent 6f2b64f commit efb46e5
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Showing 2 changed files with 79 additions and 31 deletions.
8 changes: 8 additions & 0 deletions .gitignore
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Original file line number Diff line number Diff line change
Expand Up @@ -120,3 +120,11 @@ Tools/ssl/win32
# Ignore ./python binary on Unix but still look into ./Python/ directory.
/python
!/Python/

# Artifacts generated by 3.11 lying around when switching branches:
/_bootstrap_python
/Programs/_freeze_module
/Modules/Setup.bootstrap
/Modules/Setup.stdlib
/Python/deepfreeze/
/Python/frozen_modules/
102 changes: 71 additions & 31 deletions Lib/test/test_ssl.py
View file
Original file line number Diff line number Diff line change
Expand Up @@ -4828,12 +4828,16 @@ class TestPreHandshakeClose(unittest.TestCase):

class SingleConnectionTestServerThread(threading.Thread):

def __init__(self, *, name, call_after_accept):
def __init__(self, *, name, call_after_accept, timeout=None):
self.call_after_accept = call_after_accept
self.received_data = b'' # set by .run()
self.wrap_error = None # set by .run()
self.listener = None # set by .start()
self.port = None # set by .start()
if timeout is None:
self.timeout = support.SHORT_TIMEOUT
else:
self.timeout = timeout
super().__init__(name=name)

def __enter__(self):
Expand All @@ -4856,13 +4860,19 @@ def start(self):
self.ssl_ctx.load_cert_chain(certfile=ONLYCERT, keyfile=ONLYKEY)
self.listener = socket.socket()
self.port = support.bind_port(self.listener)
self.listener.settimeout(2.0)
self.listener.settimeout(self.timeout)
self.listener.listen(1)
super().start()

def run(self):
conn, address = self.listener.accept()
self.listener.close()
try:
conn, address = self.listener.accept()
except TimeoutError:
# on timeout, just close the listener
return
finally:
self.listener.close()

with conn:
if self.call_after_accept(conn):
return
Expand Down Expand Up @@ -4890,8 +4900,13 @@ def non_linux_skip_if_other_okay_error(self, err):
# we're specifically trying to test. The way this test is written
# is known to work on Linux. We'll skip it anywhere else that it
# does not present as doing so.
self.skipTest(f"Could not recreate conditions on {sys.platform}:"
f" {err=}")
try:
self.skipTest(f"Could not recreate conditions on {sys.platform}:"
f" {err=}")
finally:
# gh-108342: Explicitly break the reference cycle
err = None

# If maintaining this conditional winds up being a problem.
# just turn this into an unconditional skip anything but Linux.
# The important thing is that our CI has the logic covered.
Expand All @@ -4902,7 +4917,7 @@ def test_preauth_data_to_tls_server(self):

def call_after_accept(unused):
server_accept_called.set()
if not ready_for_server_wrap_socket.wait(2.0):
if not ready_for_server_wrap_socket.wait(support.SHORT_TIMEOUT):
raise RuntimeError("wrap_socket event never set, test may fail.")
return False # Tell the server thread to continue.

Expand All @@ -4924,20 +4939,31 @@ def call_after_accept(unused):

ready_for_server_wrap_socket.set()
server.join()

wrap_error = server.wrap_error
self.assertEqual(b"", server.received_data)
self.assertIsInstance(wrap_error, OSError) # All platforms.
self.non_linux_skip_if_other_okay_error(wrap_error)
self.assertIsInstance(wrap_error, ssl.SSLError)
self.assertIn("before TLS handshake with data", wrap_error.args[1])
self.assertIn("before TLS handshake with data", wrap_error.reason)
self.assertNotEqual(0, wrap_error.args[0])
self.assertIsNone(wrap_error.library, msg="attr must exist")
server.wrap_error = None
try:
self.assertEqual(b"", server.received_data)
self.assertIsInstance(wrap_error, OSError) # All platforms.
self.non_linux_skip_if_other_okay_error(wrap_error)
self.assertIsInstance(wrap_error, ssl.SSLError)
self.assertIn("before TLS handshake with data", wrap_error.args[1])
self.assertIn("before TLS handshake with data", wrap_error.reason)
self.assertNotEqual(0, wrap_error.args[0])
self.assertIsNone(wrap_error.library, msg="attr must exist")
finally:
# gh-108342: Explicitly break the reference cycle
wrap_error = None
server = None

def test_preauth_data_to_tls_client(self):
server_can_continue_with_wrap_socket = threading.Event()
client_can_continue_with_wrap_socket = threading.Event()

def call_after_accept(conn_to_client):
if not server_can_continue_with_wrap_socket.wait(support.SHORT_TIMEOUT):
print("ERROR: test client took too long")

# This forces an immediate connection close via RST on .close().
set_socket_so_linger_on_with_zero_timeout(conn_to_client)
conn_to_client.send(
Expand All @@ -4959,8 +4985,10 @@ def call_after_accept(conn_to_client):

with socket.socket() as client:
client.connect(server.listener.getsockname())
if not client_can_continue_with_wrap_socket.wait(2.0):
self.fail("test server took too long.")
server_can_continue_with_wrap_socket.set()

if not client_can_continue_with_wrap_socket.wait(support.SHORT_TIMEOUT):
self.fail("test server took too long")
ssl_ctx = ssl.create_default_context()
try:
tls_client = ssl_ctx.wrap_socket(
Expand All @@ -4974,24 +5002,31 @@ def call_after_accept(conn_to_client):
tls_client.close()

server.join()
self.assertEqual(b"", received_data)
self.assertIsInstance(wrap_error, OSError) # All platforms.
self.non_linux_skip_if_other_okay_error(wrap_error)
self.assertIsInstance(wrap_error, ssl.SSLError)
self.assertIn("before TLS handshake with data", wrap_error.args[1])
self.assertIn("before TLS handshake with data", wrap_error.reason)
self.assertNotEqual(0, wrap_error.args[0])
self.assertIsNone(wrap_error.library, msg="attr must exist")
try:
self.assertEqual(b"", received_data)
self.assertIsInstance(wrap_error, OSError) # All platforms.
self.non_linux_skip_if_other_okay_error(wrap_error)
self.assertIsInstance(wrap_error, ssl.SSLError)
self.assertIn("before TLS handshake with data", wrap_error.args[1])
self.assertIn("before TLS handshake with data", wrap_error.reason)
self.assertNotEqual(0, wrap_error.args[0])
self.assertIsNone(wrap_error.library, msg="attr must exist")
finally:
# gh-108342: Explicitly break the reference cycle
wrap_error = None
server = None

def test_https_client_non_tls_response_ignored(self):

server_responding = threading.Event()

class SynchronizedHTTPSConnection(http.client.HTTPSConnection):
def connect(self):
# Call clear text HTTP connect(), not the encrypted HTTPS (TLS)
# connect(): wrap_socket() is called manually below.
http.client.HTTPConnection.connect(self)

# Wait for our fault injection server to have done its thing.
if not server_responding.wait(1.0) and support.verbose:
if not server_responding.wait(support.SHORT_TIMEOUT) and support.verbose:
sys.stdout.write("server_responding event never set.")
self.sock = self._context.wrap_socket(
self.sock, server_hostname=self.host)
Expand All @@ -5006,29 +5041,34 @@ def call_after_accept(conn_to_client):
server_responding.set()
return True # Tell the server to stop.

timeout = 2.0
server = self.SingleConnectionTestServerThread(
call_after_accept=call_after_accept,
name="non_tls_http_RST_responder")
name="non_tls_http_RST_responder",
timeout=timeout)
server.__enter__() # starts it
self.addCleanup(server.__exit__) # ... & unittest.TestCase stops it.
# Redundant; call_after_accept sets SO_LINGER on the accepted conn.
set_socket_so_linger_on_with_zero_timeout(server.listener)

connection = SynchronizedHTTPSConnection(
f"localhost",
server.listener.getsockname()[0],
port=server.port,
context=ssl.create_default_context(),
timeout=2.0,
timeout=timeout,
)

# There are lots of reasons this raises as desired, long before this
# test was added. Sending the request requires a successful TLS wrapped
# socket; that fails if the connection is broken. It may seem pointless
# to test this. It serves as an illustration of something that we never
# want to happen... properly not happening.
with self.assertRaises(OSError) as err_ctx:
with self.assertRaises(OSError):
connection.request("HEAD", "/test", headers={"Host": "localhost"})
response = connection.getresponse()

server.join()


def test_main(verbose=False):
if support.verbose:
Expand Down

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