https://github.com/python/cpython/commit/1994d2e5b139d825973f643b2ee4470fb34b76e0
commit: 1994d2e5b139d825973f643b2ee4470fb34b76e0
branch: 3.13
author: Miss Islington (bot) <31488909+miss-isling...@users.noreply.github.com>
committer: kumaraditya303 <kumaradi...@python.org>
date: 2025-07-03T09:37:28+05:30
summary:
[3.13] gh-135836: Fix `IndexError` in `asyncio.create_connection` with empty
exceptions list (GH-135845) (#136168)
gh-135836: Fix `IndexError` in `asyncio.create_connection` with empty
exceptions list (GH-135845)
(cherry picked from commit 0e19db653dfa1a6e750e9cede1f6922e5fd1e808)
Co-authored-by: heliang666s <147408835+heliang6...@users.noreply.github.com>
Co-authored-by: Kumar Aditya <kumaradi...@python.org>
files:
A Misc/NEWS.d/next/Library/2025-06-23-11-04-25.gh-issue-135836.-C-c4v.rst
M Lib/asyncio/base_events.py
M Lib/test/test_asyncio/test_base_events.py
diff --git a/Lib/asyncio/base_events.py b/Lib/asyncio/base_events.py
index 07ec6de6414ec2..78d20c93a1b43f 100644
--- a/Lib/asyncio/base_events.py
+++ b/Lib/asyncio/base_events.py
@@ -1164,7 +1164,7 @@ async def create_connection(
raise ExceptionGroup("create_connection failed",
exceptions)
if len(exceptions) == 1:
raise exceptions[0]
- else:
+ elif exceptions:
# If they all have the same str(), raise one.
model = str(exceptions[0])
if all(str(exc) == model for exc in exceptions):
@@ -1173,6 +1173,9 @@ async def create_connection(
# the various error messages.
raise OSError('Multiple exceptions: {}'.format(
', '.join(str(exc) for exc in exceptions)))
+ else:
+ # No exceptions were collected, raise a timeout error
+ raise TimeoutError('create_connection failed')
finally:
exceptions = None
diff --git a/Lib/test/test_asyncio/test_base_events.py
b/Lib/test/test_asyncio/test_base_events.py
index 3d3459f47c8324..bd67f9425ee4ac 100644
--- a/Lib/test/test_asyncio/test_base_events.py
+++ b/Lib/test/test_asyncio/test_base_events.py
@@ -1190,6 +1190,36 @@ def getaddrinfo(*args, **kw):
self.loop.run_until_complete(coro)
self.assertTrue(sock.close.called)
+ @patch_socket
+ def test_create_connection_happy_eyeballs_empty_exceptions(self, m_socket):
+ # See gh-135836: Fix IndexError when Happy Eyeballs algorithm
+ # results in empty exceptions list
+
+ async def getaddrinfo(*args, **kw):
+ return [(socket.AF_INET, socket.SOCK_STREAM, 0, '', ('127.0.0.1',
80)),
+ (socket.AF_INET6, socket.SOCK_STREAM, 0, '', ('::1', 80))]
+
+ def getaddrinfo_task(*args, **kwds):
+ return self.loop.create_task(getaddrinfo(*args, **kwds))
+
+ self.loop.getaddrinfo = getaddrinfo_task
+
+ # Mock staggered_race to return empty exceptions list
+ # This simulates the scenario where Happy Eyeballs algorithm
+ # cancels all attempts but doesn't properly collect exceptions
+ with mock.patch('asyncio.staggered.staggered_race') as mock_staggered:
+ # Return (None, []) - no winner, empty exceptions list
+ async def mock_race(coro_fns, delay, loop):
+ return None, []
+ mock_staggered.side_effect = mock_race
+
+ coro = self.loop.create_connection(
+ MyProto, 'example.com', 80, happy_eyeballs_delay=0.1)
+
+ # Should raise TimeoutError instead of IndexError
+ with self.assertRaisesRegex(TimeoutError, "create_connection
failed"):
+ self.loop.run_until_complete(coro)
+
def test_create_connection_host_port_sock(self):
coro = self.loop.create_connection(
MyProto, 'example.com', 80, sock=object())
diff --git
a/Misc/NEWS.d/next/Library/2025-06-23-11-04-25.gh-issue-135836.-C-c4v.rst
b/Misc/NEWS.d/next/Library/2025-06-23-11-04-25.gh-issue-135836.-C-c4v.rst
new file mode 100644
index 00000000000000..f93c9faee5863a
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2025-06-23-11-04-25.gh-issue-135836.-C-c4v.rst
@@ -0,0 +1 @@
+Fix :exc:`IndexError` in :meth:`asyncio.loop.create_connection` that could
occur when the Happy Eyeballs algorithm resulted in an empty exceptions list
during connection attempts.
_______________________________________________
Python-checkins mailing list -- python-checkins@python.org
To unsubscribe send an email to python-checkins-le...@python.org
https://mail.python.org/mailman3//lists/python-checkins.python.org
Member address: arch...@mail-archive.com
