[asvetlov]

If a client resets its connection while it waits in the listen queue, AcceptEx fails with ERROR_NETNAME_DELETED (WinError 64). The proactor serving loop then closes the listening socket, and the server stops accepting connections.

This PR turns that error into ConnectionResetError and closes the failed accept socket. The serving loop then keeps accepting on ConnectionResetError/ConnectionAbortedError, as the selector loop does.

test_accept_connection_reset reproduces the bug on Windows: without the fix it failed 3 runs out of 3, and with it the test passed 10 out of 10.

This supersedes gh-124032 and gh-124779.

• Issue: When accepting a socket connection and ERROR_NETNAME_DELETED occurs, leads this into a closing of the serving socket (BaseProactorEventLoop) #93821

🤖 Generated with Claude Code

[miss-islington-app]

Thanks @asvetlov for the PR 🌮🎉.. I'm working now to backport this PR to: 3.14, 3.15.
🐍🍒⛏🤖

[bedevere-app]

GH-161308 is a backport of this pull request to the 3.15 branch.

[bedevere-app]

GH-161309 is a backport of this pull request to the 3.14 branch.

[bedevere-bot]

⚠️⚠️⚠️ Buildbot failure ⚠️⚠️⚠️

Hi! The buildbot AMD64 FreeBSD Refleaks 3.15 (tier-3) has failed when building commit 0398aa1.

What do you need to do:

1. Don't panic.
2. Check the buildbot page in the devguide if you don't know what the buildbots are or how they work.
3. Go to the page of the buildbot that failed (https://buildbot.python.org/#/builders/2056/builds/483) and take a look at the build logs.
4. Check if the failure is related to this commit (0398aa1) or if it is a false positive.
5. If the failure is related to this commit, please, reflect that on the issue and make a new Pull Request with a fix.

You can take a look at the buildbot page here:

https://buildbot.python.org/#/builders/2056/builds/483

Failed tests:

• test_imaplib

Failed subtests:

• test_imaplib_timeout_functionality_test - test.test_imaplib.NewIMAPSSLTests.test_imaplib_timeout_functionality_test
• test_imaplib_timeout_functionality_test - test.test_imaplib.NewIMAPTests.test_imaplib_timeout_functionality_test

Summary of the results of the build (if available):

==

Click to see traceback logs

Traceback (most recent call last):
  File "/home/buildbot/buildarea/3.15.opsec-fbsd14.refleak/build/Lib/test/test_imaplib.py", line 745, in test_imaplib_timeout_functionality_test
    client = self.imap_class("localhost", addr, timeout=0.001)
  File "/home/buildbot/buildarea/3.15.opsec-fbsd14.refleak/build/Lib/imaplib.py", line 1772, in __init__
    IMAP4.__init__(self, host, port, timeout)
    ~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/buildbot/buildarea/3.15.opsec-fbsd14.refleak/build/Lib/imaplib.py", line 217, in __init__
    self.open(host, port, timeout)
    ~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^
  File "/home/buildbot/buildarea/3.15.opsec-fbsd14.refleak/build/Lib/imaplib.py", line 1785, in open
    IMAP4.open(self, host, port, timeout)
    ~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/buildbot/buildarea/3.15.opsec-fbsd14.refleak/build/Lib/imaplib.py", line 331, in open
    self.sock = self._create_socket(timeout)
                ~~~~~~~~~~~~~~~~~~~^^^^^^^^^
  File "/home/buildbot/buildarea/3.15.opsec-fbsd14.refleak/build/Lib/imaplib.py", line 1775, in _create_socket
    sock = IMAP4._create_socket(self, timeout)
  File "/home/buildbot/buildarea/3.15.opsec-fbsd14.refleak/build/Lib/imaplib.py", line 320, in _create_socket
    return socket.create_connection(address, timeout)
           ~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^
  File "/home/buildbot/buildarea/3.15.opsec-fbsd14.refleak/build/Lib/socket.py", line 887, in create_connection
    raise exceptions[0]
  File "/home/buildbot/buildarea/3.15.opsec-fbsd14.refleak/build/Lib/socket.py", line 872, in create_connection
    sock.connect(sa)
    ~~~~~~~~~~~~^^^^
ConnectionRefusedError: [Errno 61] Connection refused


Traceback (most recent call last):
  File "/home/buildbot/buildarea/3.15.opsec-fbsd14.refleak/build/Lib/test/test_imaplib.py", line 745, in test_imaplib_timeout_functionality_test
    client = self.imap_class("localhost", addr, timeout=0.001)
  File "/home/buildbot/buildarea/3.15.opsec-fbsd14.refleak/build/Lib/imaplib.py", line 217, in __init__
    self.open(host, port, timeout)
    ~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^
  File "/home/buildbot/buildarea/3.15.opsec-fbsd14.refleak/build/Lib/imaplib.py", line 331, in open
    self.sock = self._create_socket(timeout)
                ~~~~~~~~~~~~~~~~~~~^^^^^^^^^
  File "/home/buildbot/buildarea/3.15.opsec-fbsd14.refleak/build/Lib/imaplib.py", line 320, in _create_socket
    return socket.create_connection(address, timeout)
           ~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^
  File "/home/buildbot/buildarea/3.15.opsec-fbsd14.refleak/build/Lib/socket.py", line 887, in create_connection
    raise exceptions[0]
  File "/home/buildbot/buildarea/3.15.opsec-fbsd14.refleak/build/Lib/socket.py", line 872, in create_connection
    sock.connect(sa)
    ~~~~~~~~~~~~^^^^
ConnectionRefusedError: [Errno 61] Connection refused

[asvetlov]

The failure is not related to the change