Issue #23972: updates to asyncio datagram API. By Chris Laws.

Doc/library/asyncio-eventloop.rst

@@ -283,17 +283,50 @@ Creating connections
       (:class:`StreamReader`, :class:`StreamWriter`) instead of a protocol.
 
 
-.. coroutinemethod:: BaseEventLoop.create_datagram_endpoint(protocol_factory, local_addr=None, remote_addr=None, \*, family=0, proto=0, flags=0)
+.. coroutinemethod:: BaseEventLoop.create_datagram_endpoint(protocol_factory, local_addr=None, remote_addr=None, \*, family=0, proto=0, flags=0, reuse_address=None, reuse_port=None, allow_broadcast=None, sock=None)
 
    Create datagram connection: socket family :py:data:`~socket.AF_INET` or
    :py:data:`~socket.AF_INET6` depending on *host* (or *family* if specified),
-   socket type :py:data:`~socket.SOCK_DGRAM`.
+   socket type :py:data:`~socket.SOCK_DGRAM`. *protocol_factory* must be a
+   callable returning a :ref:`protocol <asyncio-protocol>` instance.
 
    This method is a :ref:`coroutine <coroutine>` which will try to
    establish the connection in the background.  When successful, the
    coroutine returns a ``(transport, protocol)`` pair.
 
-   See the :meth:`BaseEventLoop.create_connection` method for parameters.
+   Options changing how the connection is created:
+
+   * *local_addr*, if given, is a ``(local_host, local_port)`` tuple used
+     to bind the socket to locally.  The *local_host* and *local_port*
+     are looked up using :meth:`getaddrinfo`.
+
+   * *remote_addr*, if given, is a ``(remote_host, remote_port)`` tuple used
+     to connect the socket to a remote address.  The *remote_host* and
+     *remote_port* are looked up using :meth:`getaddrinfo`.
+
+   * *family*, *proto*, *flags* are the optional address family, protocol
+     and flags to be passed through to :meth:`getaddrinfo` for *host*
+     resolution. If given, these should all be integers from the
+     corresponding :mod:`socket` module constants.
+
+   * *reuse_address* tells the kernel to reuse a local socket in
+     TIME_WAIT state, without waiting for its natural timeout to
+     expire. If not specified will automatically be set to True on
+     UNIX.
+
+   * *reuse_port* tells the kernel to allow this endpoint to be bound to the
+     same port as other existing endpoints are bound to, so long as they all
+     set this flag when being created. This option is not supported on Windows
+     and some UNIX's. If the :py:data:`~socket.SO_REUSEPORT` constant is not
+     defined then this capability is unsupported.
+
+   * *allow_broadcast* tells the kernel to allow this endpoint to send
+     messages to the broadcast address.
+
+   * *sock* can optionally be specified in order to use a preexisting,
+     already connected, :class:`socket.socket` object to be used by the
+     transport. If specified, *local_addr* and *remote_addr* should be omitted
+     (must be :const:`None`).
 
    On Windows with :class:`ProactorEventLoop`, this method is not supported.
 
@@ -320,7 +353,7 @@ Creating connections
 Creating listening connections
 ------------------------------
 
-.. coroutinemethod:: BaseEventLoop.create_server(protocol_factory, host=None, port=None, \*, family=socket.AF_UNSPEC, flags=socket.AI_PASSIVE, sock=None, backlog=100, ssl=None, reuse_address=None)
+.. coroutinemethod:: BaseEventLoop.create_server(protocol_factory, host=None, port=None, \*, family=socket.AF_UNSPEC, flags=socket.AI_PASSIVE, sock=None, backlog=100, ssl=None, reuse_address=None, reuse_port=None)
 
    Create a TCP server (socket type :data:`~socket.SOCK_STREAM`) bound to
    *host* and *port*.
@@ -359,6 +392,11 @@ Creating listening connections
      expire. If not specified will automatically be set to True on
      UNIX.
 
+   * *reuse_port* tells the kernel to allow this endpoint to be bound to the
+     same port as other existing endpoints are bound to, so long as they all
+     set this flag when being created. This option is not supported on
+     Windows.
+
    This method is a :ref:`coroutine <coroutine>`.
 
    On Windows with :class:`ProactorEventLoop`, SSL/TLS is not supported.

Lib/asyncio/base_events.py

@@ -700,75 +700,109 @@ class BaseEventLoop(events.AbstractEventLoop):
     @coroutine
     def create_datagram_endpoint(self, protocol_factory,
                                  local_addr=None, remote_addr=None, *,
-                                 family=0, proto=0, flags=0):
+                                 family=0, proto=0, flags=0,
+                                 reuse_address=None, reuse_port=None,
+                                 allow_broadcast=None, sock=None):
         """Create datagram connection."""
-        if not (local_addr or remote_addr):
-            if family == 0:
-                raise ValueError('unexpected address family')
-            addr_pairs_info = (((family, proto), (None, None)),)
-        else:
-            # join address by (family, protocol)
-            addr_infos = collections.OrderedDict()
-            for idx, addr in ((0, local_addr), (1, remote_addr)):
-                if addr is not None:
-                    assert isinstance(addr, tuple) and len(addr) == 2, (
-                        '2-tuple is expected')
-
-                    infos = yield from self.getaddrinfo(
-                        *addr, family=family, type=socket.SOCK_DGRAM,
-                        proto=proto, flags=flags)
-                    if not infos:
-                        raise OSError('getaddrinfo() returned empty list')
-
-                    for fam, _, pro, _, address in infos:
-                        key = (fam, pro)
-                        if key not in addr_infos:
-                            addr_infos[key] = [None, None]
-                        addr_infos[key][idx] = address
-
-            # each addr has to have info for each (family, proto) pair
-            addr_pairs_info = [
-                (key, addr_pair) for key, addr_pair in addr_infos.items()
-                if not ((local_addr and addr_pair[0] is None) or
-                        (remote_addr and addr_pair[1] is None))]
-
-            if not addr_pairs_info:
-                raise ValueError('can not get address information')
-
-        exceptions = []
-
-        for ((family, proto),
-             (local_address, remote_address)) in addr_pairs_info:
-            sock = None
+        if sock is not None:
+            if (local_addr or remote_addr or
+                    family or proto or flags or
+                    reuse_address or reuse_port or allow_broadcast):
+                # show the problematic kwargs in exception msg
+                opts = dict(local_addr=local_addr, remote_addr=remote_addr,
+                            family=family, proto=proto, flags=flags,
+                            reuse_address=reuse_address, reuse_port=reuse_port,
+                            allow_broadcast=allow_broadcast)
+                problems = ', '.join(
+                    '{}={}'.format(k, v) for k, v in opts.items() if v)
+                raise ValueError(
+                    'socket modifier keyword arguments can not be used '
+                    'when sock is specified. ({})'.format(problems))
+            sock.setblocking(False)
             r_addr = None
-            try:
-                sock = socket.socket(
-                    family=family, type=socket.SOCK_DGRAM, proto=proto)
-                sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
-                sock.setblocking(False)
-
-                if local_addr:
-                    sock.bind(local_address)
-                if remote_addr:
-                    yield from self.sock_connect(sock, remote_address)
-                    r_addr = remote_address
-            except OSError as exc:
-                if sock is not None:
-                    sock.close()
-                exceptions.append(exc)
-            except:
-                if sock is not None:
-                    sock.close()
-                raise
-            else:
-                break
         else:
-            raise exceptions[0]
+            if not (local_addr or remote_addr):
+                if family == 0:
+                    raise ValueError('unexpected address family')
+                addr_pairs_info = (((family, proto), (None, None)),)
+            else:
+                # join address by (family, protocol)
+                addr_infos = collections.OrderedDict()
+                for idx, addr in ((0, local_addr), (1, remote_addr)):
+                    if addr is not None:
+                        assert isinstance(addr, tuple) and len(addr) == 2, (
+                            '2-tuple is expected')
+
+                        infos = yield from self.getaddrinfo(
+                            *addr, family=family, type=socket.SOCK_DGRAM,
+                            proto=proto, flags=flags)
+                        if not infos:
+                            raise OSError('getaddrinfo() returned empty list')
+
+                        for fam, _, pro, _, address in infos:
+                            key = (fam, pro)
+                            if key not in addr_infos:
+                                addr_infos[key] = [None, None]
+                            addr_infos[key][idx] = address
+
+                # each addr has to have info for each (family, proto) pair
+                addr_pairs_info = [
+                    (key, addr_pair) for key, addr_pair in addr_infos.items()
+                    if not ((local_addr and addr_pair[0] is None) or
+                            (remote_addr and addr_pair[1] is None))]
+
+                if not addr_pairs_info:
+                    raise ValueError('can not get address information')
+
+            exceptions = []
+
+            if reuse_address is None:
+                reuse_address = os.name == 'posix' and sys.platform != 'cygwin'
+
+            for ((family, proto),
+                 (local_address, remote_address)) in addr_pairs_info:
+                sock = None
+                r_addr = None
+                try:
+                    sock = socket.socket(
+                        family=family, type=socket.SOCK_DGRAM, proto=proto)
+                    if reuse_address:
+                        sock.setsockopt(
+                            socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
+                    if reuse_port:
+                        if not hasattr(socket, 'SO_REUSEPORT'):
+                            raise ValueError(
+                                'reuse_port not supported by socket module')
+                        else:
+                            sock.setsockopt(
+                                socket.SOL_SOCKET, socket.SO_REUSEPORT, 1)
+                    if allow_broadcast:
+                        sock.setsockopt(
+                            socket.SOL_SOCKET, socket.SO_BROADCAST, 1)
+                    sock.setblocking(False)
+
+                    if local_addr:
+                        sock.bind(local_address)
+                    if remote_addr:
+                        yield from self.sock_connect(sock, remote_address)
+                        r_addr = remote_address
+                except OSError as exc:
+                    if sock is not None:
+                        sock.close()
+                    exceptions.append(exc)
+                except:
+                    if sock is not None:
+                        sock.close()
+                    raise
+                else:
+                    break
+            else:
+                raise exceptions[0]
 
         protocol = protocol_factory()
         waiter = futures.Future(loop=self)
-        transport = self._make_datagram_transport(sock, protocol, r_addr,
-                                                  waiter)
+        transport = self._make_datagram_transport(
+            sock, protocol, r_addr, waiter)
         if self._debug:
             if local_addr:
                 logger.info("Datagram endpoint local_addr=%r remote_addr=%r "
@@ -804,7 +838,8 @@ class BaseEventLoop(events.AbstractEventLoop):
                       sock=None,
                       backlog=100,
                       ssl=None,
-                      reuse_address=None):
+                      reuse_address=None,
+                      reuse_port=None):
         """Create a TCP server.
 
         The host parameter can be a string, in that case the TCP server is bound
@@ -857,8 +892,15 @@ class BaseEventLoop(events.AbstractEventLoop):
                         continue
                     sockets.append(sock)
                     if reuse_address:
-                        sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR,
-                                        True)
+                        sock.setsockopt(
+                            socket.SOL_SOCKET, socket.SO_REUSEADDR, True)
+                    if reuse_port:
+                        if not hasattr(socket, 'SO_REUSEPORT'):
+                            raise ValueError(
+                                'reuse_port not supported by socket module')
+                        else:
+                            sock.setsockopt(
+                                socket.SOL_SOCKET, socket.SO_REUSEPORT, True)
                     # Disable IPv4/IPv6 dual stack support (enabled by
                     # default on Linux) which makes a single socket
                     # listen on both address families.

Lib/asyncio/events.py

@@ -297,7 +297,8 @@ class AbstractEventLoop:
 
     def create_server(self, protocol_factory, host=None, port=None, *,
                       family=socket.AF_UNSPEC, flags=socket.AI_PASSIVE,
-                      sock=None, backlog=100, ssl=None, reuse_address=None):
+                      sock=None, backlog=100, ssl=None, reuse_address=None,
+                      reuse_port=None):
         """A coroutine which creates a TCP server bound to host and port.
 
         The return value is a Server object which can be used to stop
@@ -327,6 +328,11 @@ class AbstractEventLoop:
         TIME_WAIT state, without waiting for its natural timeout to
         expire. If not specified will automatically be set to True on
         UNIX.
+
+        reuse_port tells the kernel to allow this endpoint to be bound to
+        the same port as other existing endpoints are bound to, so long as
+        they all set this flag when being created. This option is not
+        supported on Windows.
         """
         raise NotImplementedError
 
@@ -358,7 +364,37 @@ class AbstractEventLoop:
 
     def create_datagram_endpoint(self, protocol_factory,
                                  local_addr=None, remote_addr=None, *,
-                                 family=0, proto=0, flags=0):
+                                 family=0, proto=0, flags=0,
+                                 reuse_address=None, reuse_port=None,
+                                 allow_broadcast=None, sock=None):
+        """A coroutine which creates a datagram endpoint.
+
+        This method will try to establish the endpoint in the background.
+        When successful, the coroutine returns a (transport, protocol) pair.
+
+        protocol_factory must be a callable returning a protocol instance.
+
+        socket family AF_INET or socket.AF_INET6 depending on host (or
+        family if specified), socket type SOCK_DGRAM.
+
+        reuse_address tells the kernel to reuse a local socket in
+        TIME_WAIT state, without waiting for its natural timeout to
+        expire. If not specified it will automatically be set to True on
+        UNIX.
+
+        reuse_port tells the kernel to allow this endpoint to be bound to
+        the same port as other existing endpoints are bound to, so long as
+        they all set this flag when being created. This option is not
+        supported on Windows and some UNIX's. If the
+        :py:data:`~socket.SO_REUSEPORT` constant is not defined then this
+        capability is unsupported.
+
+        allow_broadcast tells the kernel to allow this endpoint to send
+        messages to the broadcast address.
+
+        sock can optionally be specified in order to use a preexisting
+        socket object.
+        """
         raise NotImplementedError
 
     # Pipes and subprocesses.

Lib/test/test_asyncio/test_base_events.py

@@ -3,6 +3,7 @@
 import errno
 import logging
 import math
+import os
 import socket
 import sys
 import threading
@@ -790,11 +791,11 @@ class MyProto(asyncio.Protocol):
 class MyDatagramProto(asyncio.DatagramProtocol):
     done = None
 
-    def __init__(self, create_future=False):
+    def __init__(self, create_future=False, loop=None):
         self.state = 'INITIAL'
         self.nbytes = 0
         if create_future:
-            self.done = asyncio.Future()
+            self.done = asyncio.Future(loop=loop)
 
     def connection_made(self, transport):
         self.transport = transport
@@ -1099,6 +1100,19 @@ class BaseEventLoopWithSelectorTests(test_utils.TestCase):
         f = self.loop.create_server(MyProto, '0.0.0.0', 0)
         self.assertRaises(OSError, self.loop.run_until_complete, f)
 
+    @mock.patch('asyncio.base_events.socket')
+    def test_create_server_nosoreuseport(self, m_socket):
+        m_socket.getaddrinfo = socket.getaddrinfo
+        m_socket.SOCK_STREAM = socket.SOCK_STREAM
+        m_socket.SOL_SOCKET = socket.SOL_SOCKET
+        del m_socket.SO_REUSEPORT
+        m_socket.socket.return_value = mock.Mock()
+
+        f = self.loop.create_server(
+            MyProto, '0.0.0.0', 0, reuse_port=True)
+
+        self.assertRaises(ValueError, self.loop.run_until_complete, f)
+
     @mock.patch('asyncio.base_events.socket')
     def test_create_server_cant_bind(self, m_socket):
 
@@ -1199,6 +1213,128 @@ class BaseEventLoopWithSelectorTests(test_utils.TestCase):
         self.assertRaises(Err, self.loop.run_until_complete, fut)
         self.assertTrue(m_sock.close.called)
 
+    def test_create_datagram_endpoint_sock(self):
+        sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
+        fut = self.loop.create_datagram_endpoint(
+            lambda: MyDatagramProto(create_future=True, loop=self.loop),
+            sock=sock)
+        transport, protocol = self.loop.run_until_complete(fut)
+        transport.close()
+        self.loop.run_until_complete(protocol.done)
+        self.assertEqual('CLOSED', protocol.state)
+
+    def test_create_datagram_endpoint_sock_sockopts(self):
+        fut = self.loop.create_datagram_endpoint(
+            MyDatagramProto, local_addr=('127.0.0.1', 0), sock=object())
+        self.assertRaises(ValueError, self.loop.run_until_complete, fut)
+
+        fut = self.loop.create_datagram_endpoint(
+            MyDatagramProto, remote_addr=('127.0.0.1', 0), sock=object())
+        self.assertRaises(ValueError, self.loop.run_until_complete, fut)
+
+        fut = self.loop.create_datagram_endpoint(
+            MyDatagramProto, family=1, sock=object())
+        self.assertRaises(ValueError, self.loop.run_until_complete, fut)
+
+        fut = self.loop.create_datagram_endpoint(
+            MyDatagramProto, proto=1, sock=object())
+        self.assertRaises(ValueError, self.loop.run_until_complete, fut)
+
+        fut = self.loop.create_datagram_endpoint(
+            MyDatagramProto, flags=1, sock=object())
+        self.assertRaises(ValueError, self.loop.run_until_complete, fut)
+
+        fut = self.loop.create_datagram_endpoint(
+            MyDatagramProto, reuse_address=True, sock=object())
+        self.assertRaises(ValueError, self.loop.run_until_complete, fut)
+
+        fut = self.loop.create_datagram_endpoint(
+            MyDatagramProto, reuse_port=True, sock=object())
+        self.assertRaises(ValueError, self.loop.run_until_complete, fut)
+
+        fut = self.loop.create_datagram_endpoint(
+            MyDatagramProto, allow_broadcast=True, sock=object())
+        self.assertRaises(ValueError, self.loop.run_until_complete, fut)
+
+    def test_create_datagram_endpoint_sockopts(self):
+        # Socket options should not be applied unless asked for.
+        # SO_REUSEADDR defaults to on for UNIX.
+        # SO_REUSEPORT is not available on all platforms.
+
+        coro = self.loop.create_datagram_endpoint(
+            lambda: MyDatagramProto(create_future=True, loop=self.loop),
+            local_addr=('127.0.0.1', 0))
+        transport, protocol = self.loop.run_until_complete(coro)
+        sock = transport.get_extra_info('socket')
+
+        reuse_address_default_on = (
+            os.name == 'posix' and sys.platform != 'cygwin')
+        reuseport_supported = hasattr(socket, 'SO_REUSEPORT')
+
+        if reuse_address_default_on:
+            self.assertTrue(
+                sock.getsockopt(
+                    socket.SOL_SOCKET, socket.SO_REUSEADDR))
+        else:
+            self.assertFalse(
+                sock.getsockopt(
+                    socket.SOL_SOCKET, socket.SO_REUSEADDR))
+        if reuseport_supported:
+            self.assertFalse(
+                sock.getsockopt(
+                    socket.SOL_SOCKET, socket.SO_REUSEPORT))
+        self.assertFalse(
+            sock.getsockopt(
+                socket.SOL_SOCKET, socket.SO_BROADCAST))
+
+        transport.close()
+        self.loop.run_until_complete(protocol.done)
+        self.assertEqual('CLOSED', protocol.state)
+
+        coro = self.loop.create_datagram_endpoint(
+            lambda: MyDatagramProto(create_future=True, loop=self.loop),
+            local_addr=('127.0.0.1', 0),
+            reuse_address=True,
+            reuse_port=reuseport_supported,
+            allow_broadcast=True)
+        transport, protocol = self.loop.run_until_complete(coro)
+        sock = transport.get_extra_info('socket')
+
+        self.assertTrue(
+            sock.getsockopt(
+                socket.SOL_SOCKET, socket.SO_REUSEADDR))
+        if reuseport_supported:
+            self.assertTrue(
+                sock.getsockopt(
+                    socket.SOL_SOCKET, socket.SO_REUSEPORT))
+        else:
+            self.assertFalse(
+                sock.getsockopt(
+                    socket.SOL_SOCKET, socket.SO_REUSEPORT))
+        self.assertTrue(
+            sock.getsockopt(
+                socket.SOL_SOCKET, socket.SO_BROADCAST))
+
+        transport.close()
+        self.loop.run_until_complete(protocol.done)
+        self.assertEqual('CLOSED', protocol.state)
+
+    @mock.patch('asyncio.base_events.socket')
+    def test_create_datagram_endpoint_nosoreuseport(self, m_socket):
+        m_socket.getaddrinfo = socket.getaddrinfo
+        m_socket.SOCK_DGRAM = socket.SOCK_DGRAM
+        m_socket.SOL_SOCKET = socket.SOL_SOCKET
+        del m_socket.SO_REUSEPORT
+        m_socket.socket.return_value = mock.Mock()
+
+        coro = self.loop.create_datagram_endpoint(
+            lambda: MyDatagramProto(loop=self.loop),
+            local_addr=('127.0.0.1', 0),
+            reuse_address=False,
+            reuse_port=True)
+
+        self.assertRaises(ValueError, self.loop.run_until_complete, coro)
+
     def test_accept_connection_retry(self):
         sock = mock.Mock()
         sock.accept.side_effect = BlockingIOError()

Lib/test/test_asyncio/test_events.py

@@ -814,6 +814,32 @@ class EventLoopTestsMixin:
         # close server
         server.close()
 
+    @unittest.skipUnless(hasattr(socket, 'SO_REUSEPORT'), 'No SO_REUSEPORT')
+    def test_create_server_reuse_port(self):
+        proto = MyProto(self.loop)
+        f = self.loop.create_server(
+            lambda: proto, '0.0.0.0', 0)
+        server = self.loop.run_until_complete(f)
+        self.assertEqual(len(server.sockets), 1)
+        sock = server.sockets[0]
+        self.assertFalse(
+            sock.getsockopt(
+                socket.SOL_SOCKET, socket.SO_REUSEPORT))
+        server.close()
+
+        test_utils.run_briefly(self.loop)
+
+        proto = MyProto(self.loop)
+        f = self.loop.create_server(
+            lambda: proto, '0.0.0.0', 0, reuse_port=True)
+        server = self.loop.run_until_complete(f)
+        self.assertEqual(len(server.sockets), 1)
+        sock = server.sockets[0]
+        self.assertTrue(
+            sock.getsockopt(
+                socket.SOL_SOCKET, socket.SO_REUSEPORT))
+        server.close()
+
     def _make_unix_server(self, factory, **kwargs):
         path = test_utils.gen_unix_socket_path()
         self.addCleanup(lambda: os.path.exists(path) and os.unlink(path))
@@ -1264,6 +1290,32 @@ class EventLoopTestsMixin:
         self.assertEqual('CLOSED', client.state)
         server.transport.close()
 
+    def test_create_datagram_endpoint_sock(self):
+        sock = None
+        local_address = ('127.0.0.1', 0)
+        infos = self.loop.run_until_complete(
+            self.loop.getaddrinfo(
+                *local_address, type=socket.SOCK_DGRAM))
+        for family, type, proto, cname, address in infos:
+            try:
+                sock = socket.socket(family=family, type=type, proto=proto)
+                sock.setblocking(False)
+                sock.bind(address)
+            except:
+                pass
+            else:
+                break
+        else:
+            assert False, 'Can not create socket.'
+
+        f = self.loop.create_connection(
+            lambda: MyDatagramProto(loop=self.loop), sock=sock)
+        tr, pr = self.loop.run_until_complete(f)
+        self.assertIsInstance(tr, asyncio.Transport)
+        self.assertIsInstance(pr, MyDatagramProto)
+        tr.close()
+        self.loop.run_until_complete(pr.done)
+
     def test_internal_fds(self):
         loop = self.create_event_loop()
         if not isinstance(loop, selector_events.BaseSelectorEventLoop):

Misc/ACKS

@@ -789,6 +789,7 @@ Ben Laurie
 Simon Law
 Julia Lawall
 Chris Lawrence
+Chris Laws
 Brian Leair
 Mathieu Leduc-Hamel
 Amandine Lee

Misc/NEWS

@@ -90,6 +90,12 @@ Core and Builtins
 Library
 -------
 
+- Issue #23972: Updates asyncio datagram create method allowing reuseport
+  and reuseaddr socket options to be set prior to binding the socket.
+  Mirroring the existing asyncio create_server method the reuseaddr option
+  for datagram sockets defaults to True if the O/S is 'posix' (except if the
+  platform is Cygwin). Patch by Chris Laws.
+
 - Issue #25304: Add asyncio.run_coroutine_threadsafe().  This lets you
   submit a coroutine to a loop from another thread, returning a
   concurrent.futures.Future.  By Vincent Michel.