https://github.com/python/cpython/commit/ffa12f7437e2de6621db0b5c30b3bb0759d0a689 commit: ffa12f7437e2de6621db0b5c30b3bb0759d0a689 branch: 3.13 author: Miss Islington (bot) <[email protected]> committer: kumaraditya303 <[email protected]> date: 2026-09-05T18:35:38+05:30 summary:
[3.13] gh-127057: reschedule proactor datagram read loop after ConnectionResetError (GH-156726) (#156978) gh-127057: reschedule proactor datagram read loop after ConnectionResetError (GH-156726) (cherry picked from commit 0ea2971c6eeaaed3429b5b655b77afe24fa798a8) Co-authored-by: Thomas Grainger <[email protected]> files: A Misc/NEWS.d/next/Library/2026-08-31-00-00-00.gh-issue-127057.N9yg62.rst M Lib/asyncio/proactor_events.py M Lib/test/test_asyncio/test_events.py diff --git a/Lib/asyncio/proactor_events.py b/Lib/asyncio/proactor_events.py index 3cd8ceadaf272f5..4027ac44510c92b 100644 --- a/Lib/asyncio/proactor_events.py +++ b/Lib/asyncio/proactor_events.py @@ -571,6 +571,15 @@ def _loop_reading(self, fut=None): else: self._read_fut = self._loop._proactor.recvfrom(self._sock, self.max_size) + except ConnectionResetError as exc: + # WSARecvFrom() reports a stale ICMP port unreachable + # notification as a synchronous ConnectionResetError when the + # same socket was used to send to an address that is not + # listening. This is transient, so reschedule the read loop + # instead of leaving it dead. + self._protocol.error_received(exc) + if not self._closing: + self._loop.call_soon(self._loop_reading) except OSError as exc: self._protocol.error_received(exc) except exceptions.CancelledError: diff --git a/Lib/test/test_asyncio/test_events.py b/Lib/test/test_asyncio/test_events.py index 6f8be6dee308080..aa7e6dbcacfcf54 100644 --- a/Lib/test/test_asyncio/test_events.py +++ b/Lib/test/test_asyncio/test_events.py @@ -1454,6 +1454,60 @@ def create_socket(): transport_1.close() transport_2.close() + def test_datagram_recvfrom_connection_reset_recovers(self): + # gh-127057: a UDP socket that sent a datagram to an address that + # wasn't listening can raise ConnectionResetError on a later + # receive. The transport must keep working afterwards. + loop = self.loop + + class Protocol(asyncio.DatagramProtocol): + def connection_made(self, transport): + self.transport = transport + self.errors = [] + self.received = [] + self.datagram_received_event = loop.create_future() + + def error_received(self, exc): + self.errors.append(exc) + + def datagram_received(self, data, addr): + self.received.append(data) + if not self.datagram_received_event.done(): + self.datagram_received_event.set_result(None) + + sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM) + sock.setblocking(False) + sock.bind(('127.0.0.1', 0)) + addr = sock.getsockname() + + # Bind and immediately close a second socket to get an address + # that is guaranteed not to be listening. + closed = socket.socket(socket.AF_INET, socket.SOCK_DGRAM) + closed.bind(('127.0.0.1', 0)) + closed_addr = closed.getsockname() + closed.close() + + # Trigger the error before the socket is wrapped in a transport, + # so that the first read raises synchronously. + sock.sendto(b'x', closed_addr) + + transport, protocol = loop.run_until_complete( + loop.create_datagram_endpoint(Protocol, sock=sock)) + + transport.sendto(b'ping', addr) + loop.run_until_complete(asyncio.wait_for( + protocol.datagram_received_event, support.SHORT_TIMEOUT)) + self.assertEqual(protocol.received, [b'ping']) + + if sys.platform == 'win32': + # Other platforms don't report ICMP errors on an + # unconnected UDP socket. + self.assertEqual(len(protocol.errors), 1) + self.assertIsInstance(protocol.errors[0], ConnectionResetError) + + transport.close() + test_utils.run_briefly(loop) + def test_internal_fds(self): loop = self.create_event_loop() if not isinstance(loop, selector_events.BaseSelectorEventLoop): diff --git a/Misc/NEWS.d/next/Library/2026-08-31-00-00-00.gh-issue-127057.N9yg62.rst b/Misc/NEWS.d/next/Library/2026-08-31-00-00-00.gh-issue-127057.N9yg62.rst new file mode 100644 index 000000000000000..f47da0453249cad --- /dev/null +++ b/Misc/NEWS.d/next/Library/2026-08-31-00-00-00.gh-issue-127057.N9yg62.rst @@ -0,0 +1,3 @@ +Fix :class:`asyncio.ProactorEventLoop` UDP transports so that a +:exc:`ConnectionResetError` raised by ``WSARecvFrom`` no longer stops the +read loop. _______________________________________________ Python-checkins mailing list -- [email protected] To unsubscribe send an email to [email protected] https://mail.python.org/mailman3//lists/python-checkins.python.org Member address: [email protected]
