[3.11] gh-91227: Ignore ERROR_PORT_UNREACHABLE in proactor recvfrom() (GH-32011) (GH-117210)

(cherry picked from commit f11d0d8be8af28e1368c3c7c116218cf65ddf93e)

Co-authored-by: Erik Soma <stillusingirc@gmail.com>

5 files changed, 165 insertions, 0 deletions

diff --git a/Lib/asyncio/windows_events.py b/Lib/asyncio/windows_events.py
index b9513cfb49..10ca0260f2 100644
--- a/Lib/asyncio/windows_events.py
+++ b/Lib/asyncio/windows_events.py
@@ -513,6 +513,10 @@ class IocpProactor:
             try:
                 return ov.getresult()
             except OSError as exc:
+                # WSARecvFrom will report ERROR_PORT_UNREACHABLE when the same
+                # socket is used to send to an address that is not listening.
+                if exc.winerror == _overlapped.ERROR_PORT_UNREACHABLE:
+                    return b'', None
                 if exc.winerror in (_overlapped.ERROR_NETNAME_DELETED,
                                     _overlapped.ERROR_OPERATION_ABORTED):
                     raise ConnectionResetError(*exc.args)
@@ -533,6 +537,10 @@ class IocpProactor:
             try:
                 return ov.getresult()
             except OSError as exc:
+                # WSARecvFrom will report ERROR_PORT_UNREACHABLE when the same
+                # socket is used to send to an address that is not listening.
+                if exc.winerror == _overlapped.ERROR_PORT_UNREACHABLE:
+                    return 0, None
                 if exc.winerror in (_overlapped.ERROR_NETNAME_DELETED,
                                     _overlapped.ERROR_OPERATION_ABORTED):
                     raise ConnectionResetError(*exc.args)
diff --git a/Lib/test/test_asyncio/test_events.py b/Lib/test/test_asyncio/test_events.py
index d7871d3e53..8e3c68db55 100644
--- a/Lib/test/test_asyncio/test_events.py
+++ b/Lib/test/test_asyncio/test_events.py
@@ -1352,6 +1352,80 @@ class EventLoopTestsMixin:
         tr.close()
         self.loop.run_until_complete(pr.done)
 
+    def test_datagram_send_to_non_listening_address(self):
+        # see:
+        #   https://github.com/python/cpython/issues/91227
+        #   https://github.com/python/cpython/issues/88906
+        #   https://bugs.python.org/issue47071
+        #   https://bugs.python.org/issue44743
+        # The Proactor event loop would fail to receive datagram messages after
+        # sending a message to an address that wasn't listening.
+        loop = self.loop
+
+        class Protocol(asyncio.DatagramProtocol):
+
+            _received_datagram = None
+
+            def datagram_received(self, data, addr):
+                self._received_datagram.set_result(data)
+
+            async def wait_for_datagram_received(self):
+                self._received_datagram = loop.create_future()
+                result = await asyncio.wait_for(self._received_datagram, 10)
+                self._received_datagram = None
+                return result
+
+        def create_socket():
+            sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
+            sock.setblocking(False)
+            sock.bind(('127.0.0.1', 0))
+            return sock
+
+        socket_1 = create_socket()
+        transport_1, protocol_1 = loop.run_until_complete(
+            loop.create_datagram_endpoint(Protocol, sock=socket_1)
+        )
+        addr_1 = socket_1.getsockname()
+
+        socket_2 = create_socket()
+        transport_2, protocol_2 = loop.run_until_complete(
+            loop.create_datagram_endpoint(Protocol, sock=socket_2)
+        )
+        addr_2 = socket_2.getsockname()
+
+        # creating and immediately closing this to try to get an address that
+        # is not listening
+        socket_3 = create_socket()
+        transport_3, protocol_3 = loop.run_until_complete(
+            loop.create_datagram_endpoint(Protocol, sock=socket_3)
+        )
+        addr_3 = socket_3.getsockname()
+        transport_3.abort()
+
+        transport_1.sendto(b'a', addr=addr_2)
+        self.assertEqual(loop.run_until_complete(
+            protocol_2.wait_for_datagram_received()
+        ), b'a')
+
+        transport_2.sendto(b'b', addr=addr_1)
+        self.assertEqual(loop.run_until_complete(
+            protocol_1.wait_for_datagram_received()
+        ), b'b')
+
+        # this should send to an address that isn't listening
+        transport_1.sendto(b'c', addr=addr_3)
+        loop.run_until_complete(asyncio.sleep(0))
+
+        # transport 1 should still be able to receive messages after sending to
+        # an address that wasn't listening
+        transport_2.sendto(b'd', addr=addr_1)
+        self.assertEqual(loop.run_until_complete(
+            protocol_1.wait_for_datagram_received()
+        ), b'd')
+
+        transport_1.close()
+        transport_2.close()
+
     def test_internal_fds(self):
         loop = self.create_event_loop()
         if not isinstance(loop, selector_events.BaseSelectorEventLoop):
diff --git a/Lib/test/test_asyncio/test_sock_lowlevel.py b/Lib/test/test_asyncio/test_sock_lowlevel.py
index 1f8f4e2ddf..d0ebcc66a9 100644
--- a/Lib/test/test_asyncio/test_sock_lowlevel.py
+++ b/Lib/test/test_asyncio/test_sock_lowlevel.py
@@ -555,12 +555,93 @@ if sys.platform == 'win32':
         def create_event_loop(self):
             return asyncio.SelectorEventLoop()
 
+
     class ProactorEventLoopTests(BaseSockTestsMixin,
                                  test_utils.TestCase):
 
         def create_event_loop(self):
             return asyncio.ProactorEventLoop()
 
+
+        async def _basetest_datagram_send_to_non_listening_address(self,
+                                                                   recvfrom):
+            # see:
+            #   https://github.com/python/cpython/issues/91227
+            #   https://github.com/python/cpython/issues/88906
+            #   https://bugs.python.org/issue47071
+            #   https://bugs.python.org/issue44743
+            # The Proactor event loop would fail to receive datagram messages
+            # after sending a message to an address that wasn't listening.
+
+            def create_socket():
+                sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
+                sock.setblocking(False)
+                sock.bind(('127.0.0.1', 0))
+                return sock
+
+            socket_1 = create_socket()
+            addr_1 = socket_1.getsockname()
+
+            socket_2 = create_socket()
+            addr_2 = socket_2.getsockname()
+
+            # creating and immediately closing this to try to get an address
+            # that is not listening
+            socket_3 = create_socket()
+            addr_3 = socket_3.getsockname()
+            socket_3.shutdown(socket.SHUT_RDWR)
+            socket_3.close()
+
+            socket_1_recv_task = self.loop.create_task(recvfrom(socket_1))
+            socket_2_recv_task = self.loop.create_task(recvfrom(socket_2))
+            await asyncio.sleep(0)
+
+            await self.loop.sock_sendto(socket_1, b'a', addr_2)
+            self.assertEqual(await socket_2_recv_task, b'a')
+
+            await self.loop.sock_sendto(socket_2, b'b', addr_1)
+            self.assertEqual(await socket_1_recv_task, b'b')
+            socket_1_recv_task = self.loop.create_task(recvfrom(socket_1))
+            await asyncio.sleep(0)
+
+            # this should send to an address that isn't listening
+            await self.loop.sock_sendto(socket_1, b'c', addr_3)
+            self.assertEqual(await socket_1_recv_task, b'')
+            socket_1_recv_task = self.loop.create_task(recvfrom(socket_1))
+            await asyncio.sleep(0)
+
+            # socket 1 should still be able to receive messages after sending
+            # to an address that wasn't listening
+            socket_2.sendto(b'd', addr_1)
+            self.assertEqual(await socket_1_recv_task, b'd')
+
+            socket_1.shutdown(socket.SHUT_RDWR)
+            socket_1.close()
+            socket_2.shutdown(socket.SHUT_RDWR)
+            socket_2.close()
+
+
+        def test_datagram_send_to_non_listening_address_recvfrom(self):
+            async def recvfrom(socket):
+                data, _ = await self.loop.sock_recvfrom(socket, 4096)
+                return data
+
+            self.loop.run_until_complete(
+                self._basetest_datagram_send_to_non_listening_address(
+                    recvfrom))
+
+
+        def test_datagram_send_to_non_listening_address_recvfrom_into(self):
+            async def recvfrom_into(socket):
+                buf = bytearray(4096)
+                length, _ = await self.loop.sock_recvfrom_into(socket, buf,
+                                                               4096)
+                return buf[:length]
+
+            self.loop.run_until_complete(
+                self._basetest_datagram_send_to_non_listening_address(
+                    recvfrom_into))
+
 else:
     import selectors
 
diff --git a/Misc/NEWS.d/next/Windows/2024-02-24-23-03-43.gh-issue-91227.sL4zWC.rst b/Misc/NEWS.d/next/Windows/2024-02-24-23-03-43.gh-issue-91227.sL4zWC.rst
new file mode 100644
index 0000000000..8e53afdd61
--- /dev/null
+++ b/Misc/NEWS.d/next/Windows/2024-02-24-23-03-43.gh-issue-91227.sL4zWC.rst
@@ -0,0 +1 @@
+Fix the asyncio ProactorEventLoop implementation so that sending a datagram to an address that is not listening does not prevent receiving any more datagrams.
diff --git a/Modules/overlapped.c b/Modules/overlapped.c
index 5d6a0181c6..5bc0b5833d 100644
--- a/Modules/overlapped.c
+++ b/Modules/overlapped.c
@@ -2092,6 +2092,7 @@ overlapped_exec(PyObject *module)
     WINAPI_CONSTANT(F_DWORD,  ERROR_OPERATION_ABORTED);
     WINAPI_CONSTANT(F_DWORD,  ERROR_SEM_TIMEOUT);
     WINAPI_CONSTANT(F_DWORD,  ERROR_PIPE_BUSY);
+    WINAPI_CONSTANT(F_DWORD,  ERROR_PORT_UNREACHABLE);
     WINAPI_CONSTANT(F_DWORD,  INFINITE);
     WINAPI_CONSTANT(F_HANDLE, INVALID_HANDLE_VALUE);
     WINAPI_CONSTANT(F_HANDLE, NULL);