bpo-35934: Add socket.create_server() utility function (GH-11784)

12 files changed, 146 insertions, 65 deletions

diff --git a/Lib/test/_test_multiprocessing.py b/Lib/test/_test_multiprocessing.py
index f4239ba..553ab81 100644
--- a/Lib/test/_test_multiprocessing.py
+++ b/Lib/test/_test_multiprocessing.py
@@ -3334,9 +3334,7 @@ class _TestPicklingConnections(BaseTestCase):
             new_conn.close()
             l.close()
 
-        l = socket.socket()
-        l.bind((test.support.HOST, 0))
-        l.listen()
+        l = socket.create_server((test.support.HOST, 0))
         conn.send(l.getsockname())
         new_conn, addr = l.accept()
         conn.send(new_conn)
@@ -4345,9 +4343,7 @@ class TestWait(unittest.TestCase):
 
     def test_wait_socket(self, slow=False):
         from multiprocessing.connection import wait
-        l = socket.socket()
-        l.bind((test.support.HOST, 0))
-        l.listen()
+        l = socket.create_server((test.support.HOST, 0))
         addr = l.getsockname()
         readers = []
         procs = []
diff --git a/Lib/test/eintrdata/eintr_tester.py b/Lib/test/eintrdata/eintr_tester.py
index 5f956b5..404934c 100644
--- a/Lib/test/eintrdata/eintr_tester.py
+++ b/Lib/test/eintrdata/eintr_tester.py
@@ -285,12 +285,9 @@ class SocketEINTRTest(EINTRBaseTest):
         self._test_send(lambda sock, data: sock.sendmsg([data]))
 
     def test_accept(self):
-        sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+        sock = socket.create_server((support.HOST, 0))
         self.addCleanup(sock.close)
-
-        sock.bind((support.HOST, 0))
         port = sock.getsockname()[1]
-        sock.listen()
 
         code = '\n'.join((
             'import socket, time',
diff --git a/Lib/test/test_asyncio/functional.py b/Lib/test/test_asyncio/functional.py
index 6b5b3cc..70cd140 100644
--- a/Lib/test/test_asyncio/functional.py
+++ b/Lib/test/test_asyncio/functional.py
@@ -60,21 +60,13 @@ class FunctionalTestCaseMixin:
             else:
                 addr = ('127.0.0.1', 0)
 
-        sock = socket.socket(family, socket.SOCK_STREAM)
-
+        sock = socket.create_server(addr, family=family, backlog=backlog)
         if timeout is None:
             raise RuntimeError('timeout is required')
         if timeout <= 0:
             raise RuntimeError('only blocking sockets are supported')
         sock.settimeout(timeout)
 
-        try:
-            sock.bind(addr)
-            sock.listen(backlog)
-        except OSError as ex:
-            sock.close()
-            raise ex
-
         return TestThreadedServer(
             self, sock, server_prog, timeout, max_clients)
 
diff --git a/Lib/test/test_asyncio/test_events.py b/Lib/test/test_asyncio/test_events.py
index a2b954e..b46b614 100644
--- a/Lib/test/test_asyncio/test_events.py
+++ b/Lib/test/test_asyncio/test_events.py
@@ -667,9 +667,7 @@ class EventLoopTestsMixin:
                 super().data_received(data)
                 self.transport.write(expected_response)
 
-        lsock = socket.socket()
-        lsock.bind(('127.0.0.1', 0))
-        lsock.listen(1)
+        lsock = socket.create_server(('127.0.0.1', 0), backlog=1)
         addr = lsock.getsockname()
 
         message = b'test data'
@@ -1118,9 +1116,7 @@ class EventLoopTestsMixin:
                 super().connection_made(transport)
                 proto.set_result(self)
 
-        sock_ob = socket.socket(type=socket.SOCK_STREAM)
-        sock_ob.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
-        sock_ob.bind(('0.0.0.0', 0))
+        sock_ob = socket.create_server(('0.0.0.0', 0))
 
         f = self.loop.create_server(TestMyProto, sock=sock_ob)
         server = self.loop.run_until_complete(f)
@@ -1136,9 +1132,7 @@ class EventLoopTestsMixin:
         server.close()
 
     def test_create_server_addr_in_use(self):
-        sock_ob = socket.socket(type=socket.SOCK_STREAM)
-        sock_ob.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
-        sock_ob.bind(('0.0.0.0', 0))
+        sock_ob = socket.create_server(('0.0.0.0', 0))
 
         f = self.loop.create_server(MyProto, sock=sock_ob)
         server = self.loop.run_until_complete(f)
diff --git a/Lib/test/test_asyncio/test_streams.py b/Lib/test/test_asyncio/test_streams.py
index 043fac7..630f91d 100644
--- a/Lib/test/test_asyncio/test_streams.py
+++ b/Lib/test/test_asyncio/test_streams.py
@@ -592,8 +592,7 @@ class StreamTests(test_utils.TestCase):
                 await client_writer.wait_closed()
 
             def start(self):
-                sock = socket.socket()
-                sock.bind(('127.0.0.1', 0))
+                sock = socket.create_server(('127.0.0.1', 0))
                 self.server = self.loop.run_until_complete(
                     asyncio.start_server(self.handle_client,
                                          sock=sock,
@@ -605,8 +604,7 @@ class StreamTests(test_utils.TestCase):
                                                          client_writer))
 
             def start_callback(self):
-                sock = socket.socket()
-                sock.bind(('127.0.0.1', 0))
+                sock = socket.create_server(('127.0.0.1', 0))
                 addr = sock.getsockname()
                 sock.close()
                 self.server = self.loop.run_until_complete(
@@ -796,10 +794,7 @@ os.close(fd)
 
         def server():
             # Runs in a separate thread.
-            sock = socket.socket()
-            with sock:
-                sock.bind(('localhost', 0))
-                sock.listen(1)
+            with socket.create_server(('localhost', 0)) as sock:
                 addr = sock.getsockname()
                 q.put(addr)
                 clt, _ = sock.accept()
diff --git a/Lib/test/test_epoll.py b/Lib/test/test_epoll.py
index 53ce1d5..8ac0f31 100644
--- a/Lib/test/test_epoll.py
+++ b/Lib/test/test_epoll.py
@@ -41,9 +41,7 @@ except OSError as e:
 class TestEPoll(unittest.TestCase):
 
     def setUp(self):
-        self.serverSocket = socket.socket()
-        self.serverSocket.bind(('127.0.0.1', 0))
-        self.serverSocket.listen()
+        self.serverSocket = socket.create_server(('127.0.0.1', 0))
         self.connections = [self.serverSocket]
 
     def tearDown(self):
diff --git a/Lib/test/test_ftplib.py b/Lib/test/test_ftplib.py
index da8ba32..b0e4641 100644
--- a/Lib/test/test_ftplib.py
+++ b/Lib/test/test_ftplib.py
@@ -132,9 +132,7 @@ class DummyFTPHandler(asynchat.async_chat):
         self.push('200 active data connection established')
 
     def cmd_pasv(self, arg):
-        with socket.socket() as sock:
-            sock.bind((self.socket.getsockname()[0], 0))
-            sock.listen()
+        with socket.create_server((self.socket.getsockname()[0], 0)) as sock:
             sock.settimeout(TIMEOUT)
             ip, port = sock.getsockname()[:2]
             ip = ip.replace('.', ','); p1 = port / 256; p2 = port % 256
@@ -150,9 +148,8 @@ class DummyFTPHandler(asynchat.async_chat):
         self.push('200 active data connection established')
 
     def cmd_epsv(self, arg):
-        with socket.socket(socket.AF_INET6) as sock:
-            sock.bind((self.socket.getsockname()[0], 0))
-            sock.listen()
+        with socket.create_server((self.socket.getsockname()[0], 0),
+                                  family=socket.AF_INET6) as sock:
             sock.settimeout(TIMEOUT)
             port = sock.getsockname()[1]
             self.push('229 entering extended passive mode (|||%d|)' %port)
diff --git a/Lib/test/test_httplib.py b/Lib/test/test_httplib.py
index 4755f8b..6591461 100644
--- a/Lib/test/test_httplib.py
+++ b/Lib/test/test_httplib.py
@@ -1118,11 +1118,8 @@ class BasicTest(TestCase):
 
     def test_response_fileno(self):
         # Make sure fd returned by fileno is valid.
-        serv = socket.socket(
-            socket.AF_INET, socket.SOCK_STREAM, socket.IPPROTO_TCP)
+        serv = socket.create_server((HOST, 0))
         self.addCleanup(serv.close)
-        serv.bind((HOST, 0))
-        serv.listen()
 
         result = None
         def run_server():
diff --git a/Lib/test/test_kqueue.py b/Lib/test/test_kqueue.py
index 1099c75..998fd9d 100644
--- a/Lib/test/test_kqueue.py
+++ b/Lib/test/test_kqueue.py
@@ -110,9 +110,7 @@ class TestKQueue(unittest.TestCase):
 
 
     def test_queue_event(self):
-        serverSocket = socket.socket()
-        serverSocket.bind(('127.0.0.1', 0))
-        serverSocket.listen()
+        serverSocket = socket.create_server(('127.0.0.1', 0))
         client = socket.socket()
         client.setblocking(False)
         try:
diff --git a/Lib/test/test_socket.py b/Lib/test/test_socket.py
index 8a990ea..b0bdb11 100644
--- a/Lib/test/test_socket.py
+++ b/Lib/test/test_socket.py
@@ -6068,9 +6068,133 @@ class TestMSWindowsTCPFlags(unittest.TestCase):
         self.assertEqual([], unknown,
             "New TCP flags were discovered. See bpo-32394 for more information")
 
+
+class CreateServerTest(unittest.TestCase):
+
+    def test_address(self):
+        port = support.find_unused_port()
+        with socket.create_server(("127.0.0.1", port)) as sock:
+            self.assertEqual(sock.getsockname()[0], "127.0.0.1")
+            self.assertEqual(sock.getsockname()[1], port)
+        if support.IPV6_ENABLED:
+            with socket.create_server(("::1", port),
+                                      family=socket.AF_INET6) as sock:
+                self.assertEqual(sock.getsockname()[0], "::1")
+                self.assertEqual(sock.getsockname()[1], port)
+
+    def test_family_and_type(self):
+        with socket.create_server(("127.0.0.1", 0)) as sock:
+            self.assertEqual(sock.family, socket.AF_INET)
+            self.assertEqual(sock.type, socket.SOCK_STREAM)
+        if support.IPV6_ENABLED:
+            with socket.create_server(("::1", 0), family=socket.AF_INET6) as s:
+                self.assertEqual(s.family, socket.AF_INET6)
+                self.assertEqual(sock.type, socket.SOCK_STREAM)
+
+    def test_reuse_port(self):
+        if not hasattr(socket, "SO_REUSEPORT"):
+            with self.assertRaises(ValueError):
+                socket.create_server(("localhost", 0), reuse_port=True)
+        else:
+            with socket.create_server(("localhost", 0)) as sock:
+                opt = sock.getsockopt(socket.SOL_SOCKET, socket.SO_REUSEPORT)
+                self.assertEqual(opt, 0)
+            with socket.create_server(("localhost", 0), reuse_port=True) as sock:
+                opt = sock.getsockopt(socket.SOL_SOCKET, socket.SO_REUSEPORT)
+                self.assertNotEqual(opt, 0)
+
+    @unittest.skipIf(not hasattr(_socket, 'IPPROTO_IPV6') or
+                     not hasattr(_socket, 'IPV6_V6ONLY'),
+                     "IPV6_V6ONLY option not supported")
+    @unittest.skipUnless(support.IPV6_ENABLED, 'IPv6 required for this test')
+    def test_ipv6_only_default(self):
+        with socket.create_server(("::1", 0), family=socket.AF_INET6) as sock:
+            assert sock.getsockopt(socket.IPPROTO_IPV6, socket.IPV6_V6ONLY)
+
+    @unittest.skipIf(not socket.has_dualstack_ipv6(),
+                     "dualstack_ipv6 not supported")
+    @unittest.skipUnless(support.IPV6_ENABLED, 'IPv6 required for this test')
+    def test_dualstack_ipv6_family(self):
+        with socket.create_server(("::1", 0), family=socket.AF_INET6,
+                                  dualstack_ipv6=True) as sock:
+            self.assertEqual(sock.family, socket.AF_INET6)
+
+
+class CreateServerFunctionalTest(unittest.TestCase):
+    timeout = 3
+
+    def setUp(self):
+        self.thread = None
+
+    def tearDown(self):
+        if self.thread is not None:
+            self.thread.join(self.timeout)
+
+    def echo_server(self, sock):
+        def run(sock):
+            with sock:
+                conn, _ = sock.accept()
+                with conn:
+                    event.wait(self.timeout)
+                    msg = conn.recv(1024)
+                    if not msg:
+                        return
+                    conn.sendall(msg)
+
+        event = threading.Event()
+        sock.settimeout(self.timeout)
+        self.thread = threading.Thread(target=run, args=(sock, ))
+        self.thread.start()
+        event.set()
+
+    def echo_client(self, addr, family):
+        with socket.socket(family=family) as sock:
+            sock.settimeout(self.timeout)
+            sock.connect(addr)
+            sock.sendall(b'foo')
+            self.assertEqual(sock.recv(1024), b'foo')
+
+    def test_tcp4(self):
+        port = support.find_unused_port()
+        with socket.create_server(("", port)) as sock:
+            self.echo_server(sock)
+            self.echo_client(("127.0.0.1", port), socket.AF_INET)
+
+    @unittest.skipUnless(support.IPV6_ENABLED, 'IPv6 required for this test')
+    def test_tcp6(self):
+        port = support.find_unused_port()
+        with socket.create_server(("", port),
+                                  family=socket.AF_INET6) as sock:
+            self.echo_server(sock)
+            self.echo_client(("::1", port), socket.AF_INET6)
+
+    # --- dual stack tests
+
+    @unittest.skipIf(not socket.has_dualstack_ipv6(),
+                     "dualstack_ipv6 not supported")
+    @unittest.skipUnless(support.IPV6_ENABLED, 'IPv6 required for this test')
+    def test_dual_stack_client_v4(self):
+        port = support.find_unused_port()
+        with socket.create_server(("", port), family=socket.AF_INET6,
+                                  dualstack_ipv6=True) as sock:
+            self.echo_server(sock)
+            self.echo_client(("127.0.0.1", port), socket.AF_INET)
+
+    @unittest.skipIf(not socket.has_dualstack_ipv6(),
+                     "dualstack_ipv6 not supported")
+    @unittest.skipUnless(support.IPV6_ENABLED, 'IPv6 required for this test')
+    def test_dual_stack_client_v6(self):
+        port = support.find_unused_port()
+        with socket.create_server(("", port), family=socket.AF_INET6,
+                                  dualstack_ipv6=True) as sock:
+            self.echo_server(sock)
+            self.echo_client(("::1", port), socket.AF_INET6)
+
+
 def test_main():
     tests = [GeneralModuleTests, BasicTCPTest, TCPCloserTest, TCPTimeoutTest,
-             TestExceptions, BufferIOTest, BasicTCPTest2, BasicUDPTest, UDPTimeoutTest ]
+             TestExceptions, BufferIOTest, BasicTCPTest2, BasicUDPTest,
+             UDPTimeoutTest, CreateServerTest, CreateServerFunctionalTest]
 
     tests.extend([
         NonBlockingTCPTests,
diff --git a/Lib/test/test_ssl.py b/Lib/test/test_ssl.py
index 5571822..4444e94 100644
--- a/Lib/test/test_ssl.py
+++ b/Lib/test/test_ssl.py
@@ -765,9 +765,7 @@ class BasicSocketTests(unittest.TestCase):
 
     def test_unknown_channel_binding(self):
         # should raise ValueError for unknown type
-        s = socket.socket(socket.AF_INET)
-        s.bind(('127.0.0.1', 0))
-        s.listen()
+        s = socket.create_server(('127.0.0.1', 0))
         c = socket.socket(socket.AF_INET)
         c.connect(s.getsockname())
         with test_wrap_socket(c, do_handshake_on_connect=False) as ss:
@@ -1663,11 +1661,8 @@ class SSLErrorTests(unittest.TestCase):
         ctx = ssl.SSLContext(ssl.PROTOCOL_TLS_CLIENT)
         ctx.check_hostname = False
         ctx.verify_mode = ssl.CERT_NONE
-        with socket.socket() as s:
-            s.bind(("127.0.0.1", 0))
-            s.listen()
-            c = socket.socket()
-            c.connect(s.getsockname())
+        with socket.create_server(("127.0.0.1", 0)) as s:
+            c = socket.create_connection(s.getsockname())
             c.setblocking(False)
             with ctx.wrap_socket(c, False, do_handshake_on_connect=False) as c:
                 with self.assertRaises(ssl.SSLWantReadError) as cm:
diff --git a/Lib/test/test_support.py b/Lib/test/test_support.py
index 4a8f3c5..cb664ba 100644
--- a/Lib/test/test_support.py
+++ b/Lib/test/test_support.py
@@ -91,14 +91,12 @@ class TestSupport(unittest.TestCase):
             support.rmtree('__pycache__')
 
     def test_HOST(self):
-        s = socket.socket()
-        s.bind((support.HOST, 0))
+        s = socket.create_server((support.HOST, 0))
         s.close()
 
     def test_find_unused_port(self):
         port = support.find_unused_port()
-        s = socket.socket()
-        s.bind((support.HOST, port))
+        s = socket.create_server((support.HOST, port))
         s.close()
 
     def test_bind_port(self):