Demo to produce 'bad rsv 4''

BadRSV.java

import java.net.InetSocketAddress;
import java.net.URI;
import java.util.Collections;
import java.util.List;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.TimeUnit;

import org.java_websocket.WebSocket;
import org.java_websocket.WebSocketImpl;
import org.java_websocket.client.WebSocketClient;
import org.java_websocket.drafts.Draft;
import org.java_websocket.drafts.Draft_17;
import org.java_websocket.handshake.ClientHandshake;
import org.java_websocket.handshake.ServerHandshake;
import org.java_websocket.server.WebSocketServer;

class Client extends WebSocketClient {

    Client(URI serverUri) {
        super(serverUri);
    }

    @Override
    public void onOpen(ServerHandshake serverHandshake) {
        //NO-OP
    }

    @Override
    public void onMessage(String s) {
        //NO-OP
    }

    @Override
    public void onClose(int i, String s, boolean b) {
        //NO-OP
    }

    @Override
    public void onError(Exception e) {
        e.printStackTrace();
    }
}

class Server extends WebSocketServer {

    Server(InetSocketAddress address, List<Draft> drafts) {
        super(address, drafts);
    }

    @Override
    public void onOpen(
            final WebSocket webSocket, ClientHandshake clientHandshake) {
        //NO-OP
    }

    @Override
    public void onClose(WebSocket webSocket, int i, String s, boolean b) {
        //NO-OP
    }

    @Override
    public void onMessage(WebSocket webSocket, String s) {
        //NO-OP
    }

    @Override
    public void onError(WebSocket webSocket, Exception e) {
        //NO-OP
    }

    @Override
    public void onStart() {
        BadRSV.startLatch.countDown();
    }
}

public class BadRSV {
    private static final Draft DRAFT = new Draft_17();
    public static final CountDownLatch startLatch = new CountDownLatch(1);

    static {
        WebSocketImpl.DEBUG = true;
    }

    public static void main(String[] args) throws InterruptedException {

        Server server = new Server(new InetSocketAddress("localhost", 8080),
                                   Collections.singletonList(DRAFT));
        server.start();
        startLatch.await();

        Client client = new Client(URI.create("ws://localhost:8080"));
        client.connect();
        TimeUnit.MILLISECONDS.sleep(50);
        client.close();
    }
}

output

write(153): {GET / HTTP/1.1
Connection: Upgrade
Host: localhost:8080
Sec-WebSocket-Key: o/Et8V6ZSwi6K/0hydg/2g==
Sec-WebSocket-Version: 13
Upgrade: websocket

}
process(153): {GET / HTTP/1.1
Connection: Upgrade
Host: localhost:8080
Sec-WebSocket-Key: o/Et8V6ZSwi6K/0hydg/2g==
Sec-WebSocket-Version: 13
Upgrade: websocket

}
org.java_websocket.exceptions.InvalidFrameException: bad rsv 4
	at org.java_websocket.drafts.Draft_10.translateSingleFrame(Draft_10.java:297)
	at org.java_websocket.drafts.Draft_10.translateFrame(Draft_10.java:273)
	at org.java_websocket.WebSocketImpl.decodeFrames(WebSocketImpl.java:318)
	at org.java_websocket.WebSocketImpl.decode(WebSocketImpl.java:154)
	at org.java_websocket.client.WebSocketClient.run(WebSocketClient.java:241)
	at java.lang.Thread.run(Thread.java:745)
write(129): {HTTP/1.1 101 Switching Protocols
Connection: Upgrade
Sec-WebSocket-Accept: m+lzNTcC9gXRbi/++l30hc8ZsS4=
Upgrade: websocket

}
open using draft: Draft_17
process(129): {HTTP/1.1 101 Switching Protocols
Connection: Upgrade
Sec-WebSocket-Accept: m+lzNTcC9gXRbi/++l30hc8ZsS4=
Upgrade: websocket

}