cpython/Lib/test/test_socketserver.py

"""
Test suite for socketserver.
"""

import contextlib
import io
import os
import select
import signal
import socket
import tempfile
import threading
import unittest
import socketserver

import test.support
from test.support import reap_children, verbose
from test.support import os_helper
from test.support import socket_helper
from test.support import threading_helper


test.support.requires("network")
test.support.requires_working_socket(module=True)


TEST_STR = b"hello world\n"
HOST = socket_helper.HOST

HAVE_UNIX_SOCKETS = hasattr(socket, "AF_UNIX")
requires_unix_sockets = unittest.skipUnless(HAVE_UNIX_SOCKETS,
                                            'requires Unix sockets')
HAVE_FORKING = test.support.has_fork_support
requires_forking = unittest.skipUnless(HAVE_FORKING, 'requires forking')

def signal_alarm(n):
    """Call signal.alarm when it exists (i.e. not on Windows)."""
    if hasattr(signal, 'alarm'):
        signal.alarm(n)

# Remember real select() to avoid interferences with mocking
_real_select = select.select

def receive(sock, n, timeout=test.support.SHORT_TIMEOUT):
    r, w, x = _real_select([sock], [], [], timeout)
    if sock in r:
        return sock.recv(n)
    else:
        raise RuntimeError("timed out on %r" % (sock,))

if HAVE_UNIX_SOCKETS and HAVE_FORKING:
    class ForkingUnixStreamServer(socketserver.ForkingMixIn,
                                  socketserver.UnixStreamServer):
        pass

    class ForkingUnixDatagramServer(socketserver.ForkingMixIn,
                                    socketserver.UnixDatagramServer):
        pass


@contextlib.contextmanager
def simple_subprocess(testcase):
    """Tests that a custom child process is not waited on (Issue 1540386)"""
    pid = os.fork()
    if pid == 0:
        # Don't raise an exception; it would be caught by the test harness.
        os._exit(72)
    try:
        yield None
    except:
        raise
    finally:
        test.support.wait_process(pid, exitcode=72)


class SocketServerTest(unittest.TestCase):
    """Test all socket servers."""

    def setUp(self):
        signal_alarm(60)  # Kill deadlocks after 60 seconds.
        self.port_seed = 0
        self.test_files = []

    def tearDown(self):
        signal_alarm(0)  # Didn't deadlock.
        reap_children()

        for fn in self.test_files:
            try:
                os.remove(fn)
            except OSError:
                pass
        self.test_files[:] = []

    def pickaddr(self, proto):
        if proto == socket.AF_INET:
            return (HOST, 0)
        else:
            # XXX: We need a way to tell AF_UNIX to pick its own name
            # like AF_INET provides port==0.
            dir = None
            fn = tempfile.mktemp(prefix='unix_socket.', dir=dir)
            self.test_files.append(fn)
            return fn

    def make_server(self, addr, svrcls, hdlrbase):
        class MyServer(svrcls):
            def handle_error(self, request, client_address):
                self.close_request(request)
                raise

        class MyHandler(hdlrbase):
            def handle(self):
                line = self.rfile.readline()
                self.wfile.write(line)

        if verbose: print("creating server")
        try:
            server = MyServer(addr, MyHandler)
        except PermissionError as e:
            # Issue 29184: cannot bind() a Unix socket on Android.
            self.skipTest('Cannot create server (%s, %s): %s' %
                          (svrcls, addr, e))
        self.assertEqual(server.server_address, server.socket.getsockname())
        return server

    @threading_helper.reap_threads
    def run_server(self, svrcls, hdlrbase, testfunc):
        server = self.make_server(self.pickaddr(svrcls.address_family),
                                  svrcls, hdlrbase)
        # We had the OS pick a port, so pull the real address out of
        # the server.
        addr = server.server_address
        if verbose:
            print("ADDR =", addr)
            print("CLASS =", svrcls)

        t = threading.Thread(
            name='%s serving' % svrcls,
            target=server.serve_forever,
            # Short poll interval to make the test finish quickly.
            # Time between requests is short enough that we won't wake
            # up spuriously too many times.
            kwargs={'poll_interval':0.01})
        t.daemon = True  # In case this function raises.
        t.start()
        if verbose: print("server running")
        for i in range(3):
            if verbose: print("test client", i)
            testfunc(svrcls.address_family, addr)
        if verbose: print("waiting for server")
        server.shutdown()
        t.join()
        server.server_close()
        self.assertEqual(-1, server.socket.fileno())
        if HAVE_FORKING and isinstance(server, socketserver.ForkingMixIn):
            # bpo-31151: Check that ForkingMixIn.server_close() waits until
            # all children completed
            self.assertFalse(server.active_children)
        if verbose: print("done")

    def stream_examine(self, proto, addr):
        with socket.socket(proto, socket.SOCK_STREAM) as s:
            s.connect(addr)
            s.sendall(TEST_STR)
            buf = data = receive(s, 100)
            while data and b'\n' not in buf:
                data = receive(s, 100)
                buf += data
            self.assertEqual(buf, TEST_STR)

    def dgram_examine(self, proto, addr):
        with socket.socket(proto, socket.SOCK_DGRAM) as s:
            if HAVE_UNIX_SOCKETS and proto == socket.AF_UNIX:
                s.bind(self.pickaddr(proto))
            s.sendto(TEST_STR, addr)
            buf = data = receive(s, 100)
            while data and b'\n' not in buf:
                data = receive(s, 100)
                buf += data
            self.assertEqual(buf, TEST_STR)

    def test_TCPServer(self):
        self.run_server(socketserver.TCPServer,
                        socketserver.StreamRequestHandler,
                        self.stream_examine)

    def test_ThreadingTCPServer(self):
        self.run_server(socketserver.ThreadingTCPServer,
                        socketserver.StreamRequestHandler,
                        self.stream_examine)

    @requires_forking
    def test_ForkingTCPServer(self):
        with simple_subprocess(self):
            self.run_server(socketserver.ForkingTCPServer,
                            socketserver.StreamRequestHandler,
                            self.stream_examine)

    @requires_unix_sockets
    def test_UnixStreamServer(self):
        self.run_server(socketserver.UnixStreamServer,
                        socketserver.StreamRequestHandler,
                        self.stream_examine)

    @requires_unix_sockets
    def test_ThreadingUnixStreamServer(self):
        self.run_server(socketserver.ThreadingUnixStreamServer,
                        socketserver.StreamRequestHandler,
                        self.stream_examine)

    @requires_unix_sockets
    @requires_forking
    def test_ForkingUnixStreamServer(self):
        with simple_subprocess(self):
            self.run_server(ForkingUnixStreamServer,
                            socketserver.StreamRequestHandler,
                            self.stream_examine)

    def test_UDPServer(self):
        self.run_server(socketserver.UDPServer,
                        socketserver.DatagramRequestHandler,
                        self.dgram_examine)

    def test_ThreadingUDPServer(self):
        self.run_server(socketserver.ThreadingUDPServer,
                        socketserver.DatagramRequestHandler,
                        self.dgram_examine)

    @requires_forking
    def test_ForkingUDPServer(self):
        with simple_subprocess(self):
            self.run_server(socketserver.ForkingUDPServer,
                            socketserver.DatagramRequestHandler,
                            self.dgram_examine)

    @requires_unix_sockets
    def test_UnixDatagramServer(self):
        self.run_server(socketserver.UnixDatagramServer,
                        socketserver.DatagramRequestHandler,
                        self.dgram_examine)

    @requires_unix_sockets
    def test_ThreadingUnixDatagramServer(self):
        self.run_server(socketserver.ThreadingUnixDatagramServer,
                        socketserver.DatagramRequestHandler,
                        self.dgram_examine)

    @requires_unix_sockets
    @requires_forking
    def test_ForkingUnixDatagramServer(self):
        self.run_server(ForkingUnixDatagramServer,
                        socketserver.DatagramRequestHandler,
                        self.dgram_examine)

    @threading_helper.reap_threads
    def test_shutdown(self):
        # Issue #2302: shutdown() should always succeed in making an
        # other thread leave serve_forever().
        class MyServer(socketserver.TCPServer):
            pass

        class MyHandler(socketserver.StreamRequestHandler):
            pass

        threads = []
        for i in range(20):
            s = MyServer((HOST, 0), MyHandler)
            t = threading.Thread(
                name='MyServer serving',
                target=s.serve_forever,
                kwargs={'poll_interval':0.01})
            t.daemon = True  # In case this function raises.
            threads.append((t, s))
        for t, s in threads:
            t.start()
            s.shutdown()
        for t, s in threads:
            t.join()
            s.server_close()

    def test_close_immediately(self):
        class MyServer(socketserver.ThreadingMixIn, socketserver.TCPServer):
            pass

        server = MyServer((HOST, 0), lambda: None)
        server.server_close()

    def test_tcpserver_bind_leak(self):
        # Issue #22435: the server socket wouldn't be closed if bind()/listen()
        # failed.
        # Create many servers for which bind() will fail, to see if this result
        # in FD exhaustion.
        for i in range(1024):
            with self.assertRaises(OverflowError):
                socketserver.TCPServer((HOST, -1),
                                       socketserver.StreamRequestHandler)

    def test_context_manager(self):
        with socketserver.TCPServer((HOST, 0),
                                    socketserver.StreamRequestHandler) as server:
            pass
        self.assertEqual(-1, server.socket.fileno())


class ErrorHandlerTest(unittest.TestCase):
    """Test that the servers pass normal exceptions from the handler to
    handle_error(), and that exiting exceptions like SystemExit and
    KeyboardInterrupt are not passed."""

    def tearDown(self):
        os_helper.unlink(os_helper.TESTFN)

    def test_sync_handled(self):
        BaseErrorTestServer(ValueError)
        self.check_result(handled=True)

    def test_sync_not_handled(self):
        with self.assertRaises(SystemExit):
            BaseErrorTestServer(SystemExit)
        self.check_result(handled=False)

    def test_threading_handled(self):
        ThreadingErrorTestServer(ValueError)
        self.check_result(handled=True)

    def test_threading_not_handled(self):
        with threading_helper.catch_threading_exception() as cm:
            ThreadingErrorTestServer(SystemExit)
            self.check_result(handled=False)

            self.assertIs(cm.exc_type, SystemExit)

    @requires_forking
    def test_forking_handled(self):
        ForkingErrorTestServer(ValueError)
        self.check_result(handled=True)

    @requires_forking
    def test_forking_not_handled(self):
        ForkingErrorTestServer(SystemExit)
        self.check_result(handled=False)

    def check_result(self, handled):
        with open(os_helper.TESTFN) as log:
            expected = 'Handler called\n' + 'Error handled\n' * handled
            self.assertEqual(log.read(), expected)


class BaseErrorTestServer(socketserver.TCPServer):
    def __init__(self, exception):
        self.exception = exception
        super().__init__((HOST, 0), BadHandler)
        with socket.create_connection(self.server_address):
            pass
        try:
            self.handle_request()
        finally:
            self.server_close()
        self.wait_done()

    def handle_error(self, request, client_address):
        with open(os_helper.TESTFN, 'a') as log:
            log.write('Error handled\n')

    def wait_done(self):
        pass


class BadHandler(socketserver.BaseRequestHandler):
    def handle(self):
        with open(os_helper.TESTFN, 'a') as log:
            log.write('Handler called\n')
        raise self.server.exception('Test error')


class ThreadingErrorTestServer(socketserver.ThreadingMixIn,
        BaseErrorTestServer):
    def __init__(self, *pos, **kw):
        self.done = threading.Event()
        super().__init__(*pos, **kw)

    def shutdown_request(self, *pos, **kw):
        super().shutdown_request(*pos, **kw)
        self.done.set()

    def wait_done(self):
        self.done.wait()


if HAVE_FORKING:
    class ForkingErrorTestServer(socketserver.ForkingMixIn, BaseErrorTestServer):
        pass


class SocketWriterTest(unittest.TestCase):
    def test_basics(self):
        class Handler(socketserver.StreamRequestHandler):
            def handle(self):
                self.server.wfile = self.wfile
                self.server.wfile_fileno = self.wfile.fileno()
                self.server.request_fileno = self.request.fileno()

        server = socketserver.TCPServer((HOST, 0), Handler)
        self.addCleanup(server.server_close)
        s = socket.socket(
            server.address_family, socket.SOCK_STREAM, socket.IPPROTO_TCP)
        with s:
            s.connect(server.server_address)
        server.handle_request()
        self.assertIsInstance(server.wfile, io.BufferedIOBase)
        self.assertEqual(server.wfile_fileno, server.request_fileno)

    def test_write(self):
        # Test that wfile.write() sends data immediately, and that it does
        # not truncate sends when interrupted by a Unix signal
        pthread_kill = test.support.get_attribute(signal, 'pthread_kill')

        class Handler(socketserver.StreamRequestHandler):
            def handle(self):
                self.server.sent1 = self.wfile.write(b'write data\n')
                # Should be sent immediately, without requiring flush()
                self.server.received = self.rfile.readline()
                big_chunk = b'\0' * test.support.SOCK_MAX_SIZE
                self.server.sent2 = self.wfile.write(big_chunk)

        server = socketserver.TCPServer((HOST, 0), Handler)
        self.addCleanup(server.server_close)
        interrupted = threading.Event()

        def signal_handler(signum, frame):
            interrupted.set()

        original = signal.signal(signal.SIGUSR1, signal_handler)
        self.addCleanup(signal.signal, signal.SIGUSR1, original)
        response1 = None
        received2 = None
        main_thread = threading.get_ident()

        def run_client():
            s = socket.socket(server.address_family, socket.SOCK_STREAM,
                socket.IPPROTO_TCP)
            with s, s.makefile('rb') as reader:
                s.connect(server.server_address)
                nonlocal response1
                response1 = reader.readline()
                s.sendall(b'client response\n')

                reader.read(100)
                # The main thread should now be blocking in a send() syscall.
                # But in theory, it could get interrupted by other signals,
                # and then retried. So keep sending the signal in a loop, in
                # case an earlier signal happens to be delivered at an
                # inconvenient moment.
                while True:
                    pthread_kill(main_thread, signal.SIGUSR1)
                    if interrupted.wait(timeout=float(1)):
                        break
                nonlocal received2
                received2 = len(reader.read())

        background = threading.Thread(target=run_client)
        background.start()
        server.handle_request()
        background.join()
        self.assertEqual(server.sent1, len(response1))
        self.assertEqual(response1, b'write data\n')
        self.assertEqual(server.received, b'client response\n')
        self.assertEqual(server.sent2, test.support.SOCK_MAX_SIZE)
        self.assertEqual(received2, test.support.SOCK_MAX_SIZE - 100)


class MiscTestCase(unittest.TestCase):

    def test_all(self):
        # objects defined in the module should be in __all__
        expected = []
        for name in dir(socketserver):
            if not name.startswith('_'):
                mod_object = getattr(socketserver, name)
                if getattr(mod_object, '__module__', None) == 'socketserver':
                    expected.append(name)
        self.assertCountEqual(socketserver.__all__, expected)

    def test_shutdown_request_called_if_verify_request_false(self):
        # Issue #26309: BaseServer should call shutdown_request even if
        # verify_request is False

        class MyServer(socketserver.TCPServer):
            def verify_request(self, request, client_address):
                return False

            shutdown_called = 0
            def shutdown_request(self, request):
                self.shutdown_called += 1
                socketserver.TCPServer.shutdown_request(self, request)

        server = MyServer((HOST, 0), socketserver.StreamRequestHandler)
        s = socket.socket(server.address_family, socket.SOCK_STREAM)
        s.connect(server.server_address)
        s.close()
        server.handle_request()
        self.assertEqual(server.shutdown_called, 1)
        server.server_close()

    def test_threads_reaped(self):
        """
        In #37193, users reported a memory leak
        due to the saving of every request thread. Ensure that
        not all threads are kept forever.
        """
        class MyServer(socketserver.ThreadingMixIn, socketserver.TCPServer):
            pass

        server = MyServer((HOST, 0), socketserver.StreamRequestHandler)
        for n in range(10):
            with socket.create_connection(server.server_address):
                server.handle_request()
        self.assertLess(len(server._threads), 10)
        server.server_close()


if __name__ == "__main__":
    unittest.main()