Do not crash if a random IP address tries to connect

I am trying to reproduce it, but so far I have not been successful. I'm trying with this branch: https://github.com/hazelcast/hazelcast-simulator/tree/0.9.10_beta_test

The original report says "sends stuff to the Simulator coordinator port", but the log snippet says: _"CA9-54.173.85.28-agent.out:WARN 2020-05-07 12:53:26,651 [ConnectionHandler-138.19.164.135:54836] com.hazelcast.simulator.protocol.handler.ConnectionHandler: No magic bytes sent for 10 seconds, closing connection from [id: 0x5c55546e, L:/10.165.136.8:9000 - R:/138.19.164.135:54836]"

See the filename: C_A9-54.173.85.28-agent.out:WARN. Hence I assume it's actually someone connecting to an agent rather than to a coordinator. AFAIK Coordinator does not listen to any server socket at all.

I tried to connect to both an agent and a worker but it's working as designed for me. I can see WARN 14:41:41 No magic bytes sent for 10 seconds, closing connection from [id: 0x45bac613, L:0.0.0.0/0.0.0.0:9000 ! R:/127.0.0.1:47432] in the log, the connection is killed, but the test is still running. I can see this behaviour was introduced by this changeset The changeset has rather poor tests with tons of mocking. I tried to write an integration test with real components instead of mocks yet it still working as designed for me.

Here is a test I am using to simulate this on a agent:

    @Test
    public void testAttackerSendingArbitraryRubbish() throws Exception {
        int port = agent.getPort();
        String ipAddress = agent.getPublicAddress();

        coordinator.workerStart(new RcWorkerStartOperation()
                .setHzConfig(hzConfig));

        TestSuite suite = newBasicTestSuite()
                .setDurationSeconds(60);

        StubPromise promise = new StubPromise();
        coordinator.testRun(new RcTestRunOperation(suite).setAsync(true), promise);
        assertEquals(SUCCESS, promise.get());

        String testId = promise.getResponse();
        assertEquals("C_A*_W*_T" + (initialTestIndex + 1), testId);

        SocketChannel channel = SocketChannel.open(new InetSocketAddress(ipAddress, port));
        try {
//            ByteBuffer buffer = ByteBuffer.wrap("".getBytes());
//            channel.write(buffer);
        } catch (Exception e) {
            e.printStackTrace();
        }

        assertTestCompletesEventually(testId);
    }

(paste this into CoordinatorTest)

@Danny-Hazelcast If you manage to reproduce this then please attach logs from coordinator, agent and also workers.

hazelcast / hazelcast-simulator

Do not crash if a random IP address tries to connect #1869