cpython/Lib/test/test_socketserver.py

"""
Test suite for socketserver.
"""

import contextlib
import io
import os
import select
import signal
import socket
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,))


@test.support.requires_fork()
@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.
            fn = socket_helper.create_unix_domain_name()
            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(socketserver.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(socketserver.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()