Method test_sni_callback_on_dead_references

Lib/test/test_ssl.py:1554–1595

(self)

        ctx.set_servername_callback(dummycallback)

    def test_sni_callback_on_dead_references(self):
        # See https://github.com/python/cpython/issues/146080.
        c_ctx = make_test_context()
        c_inc, c_out = ssl.MemoryBIO(), ssl.MemoryBIO()
        client = c_ctx.wrap_bio(c_inc, c_out, server_hostname=SIGNED_CERTFILE_HOSTNAME)

        def sni_callback(sock, servername, ctx): pass
        sni_callback = unittest.mock.Mock(wraps=sni_callback)
        s_ctx = make_test_context(server_side=True, certfile=SIGNED_CERTFILE)
        s_ctx.set_servername_callback(sni_callback)

        s_inc, s_out = ssl.MemoryBIO(), ssl.MemoryBIO()
        server = s_ctx.wrap_bio(s_inc, s_out, server_side=True)
        server_impl = server._sslobj

        # Perform the handshake on the client side first.
        data = do_ssl_object_handshake(client, c_out)
        sni_callback.assert_not_called()
        if data is None:
            self.skipTest("cannot establish a handshake from the client")
        s_inc.write(data)
        sni_callback.assert_not_called()
        # Delete the server object before it starts doing its handshake
        # and ensure that we did not call the SNI callback yet.
        del server
        gc.collect()
        # Try to continue the server's handshake by directly using
        # the internal SSL object. The latter is a weak reference
        # stored in the server context and has now a dead owner.
        with self.assertRaises(ssl.SSLError) as cm:
            server_impl.do_handshake()
        # The SNI C callback raised an exception before calling our callback.
        sni_callback.assert_not_called()

        # In AWS-LC, any handshake failures reports SSL_R_PARSE_TLSEXT,
        # while OpenSSL uses SSL_R_CALLBACK_FAILED on SNI callback failures.
        if IS_AWS_LC:
            libssl_error_reason = "PARSE_TLSEXT"
        else:
            libssl_error_reason = "callback failed"
        self.assertIn(libssl_error_reason, str(cm.exception))
        self.assertEqual(cm.exception.errno, ssl.SSL_ERROR_SSL)

    def test_sni_callback_refcycle(self):
        # Reference cycles through the servername callback are detected