conn.close() in server's onOpen method causes null pointer exception

[peace-maker]

Expected Behavior

Closing the websocket connection in onOpen should be possible.

Current Behavior

Calling conn.close() in public void WebSocketServer::onOpen(WebSocket conn, ClientHandshake handshake) leads to a NullPointerException. The socket is still closed correctly, but an error is logged.

Steps to Reproduce (for bugs)

1. Run a server which closes new connections right away in onOpen like below.
2. Try to connect with any client.

import java.net.InetSocketAddress;

import org.java_websocket.WebSocket;
import org.java_websocket.framing.CloseFrame;
import org.java_websocket.handshake.ClientHandshake;
import org.java_websocket.server.WebSocketServer;

public class TestWebSocketServer extends WebSocketServer {

	public TestWebSocketServer(int port) {
		super(new InetSocketAddress(port));
	}
	
	@Override
	public void onOpen(WebSocket conn, ClientHandshake handshake) {
		conn.close(CloseFrame.POLICY_VALIDATION, "Not authorized");
	}

	@Override
	public void onClose(WebSocket conn, int code, String reason, boolean remote) {
	}

	@Override
	public void onMessage(WebSocket conn, String message) {
	}

	@Override
	public void onError(WebSocket conn, Exception ex) {
	}

	@Override
	public void onStart() {
	}
	
	public static void main(String[] args) {
		TestWebSocketServer server = new TestWebSocketServer(9999);
		server.start();
	}
}

Debug log (for bugs)

Error while reading from remote connection: java.lang.NullPointerException
java.lang.NullPointerException
	at org.java_websocket.WebSocketImpl.decode(WebSocketImpl.java:214)
	at org.java_websocket.server.WebSocketServer$WebSocketWorker.run(WebSocketServer.java:881)

Context

I'm trying to implement an authentication scheme for my websocket service using a token which gets passed to the websocket server in a cookie during the handshake. Rejecting the handshake in onWebsocketHandshakeReceivedAsServer isn't an option for me, because I can't destinguish between the server rejecting the connection and the server being offline in the browser.
I need to wait until the connection is open to validate the token and send a custom closecode if it's invalid.

Your Environment

• Version used: 1.3.6
• Java version: 1.8.0_152
• Operating System and version: Windows 10 x64

[marci4]

Hello @peace-maker,

thank you for your bug report!
I will take a look at it.

Greetings
marci4

[marci4]

Hello @peace-maker,

I looked into it. The stacktrace is from a caught exception. Still this exception should not happen.

Commited a fix for this. Could you please check if this is fixed for you as well?

Greetings
marci4

Edit: sorry for the automatic close... Damn you github

[peace-maker]

Hi @marci4,

works good now without any more log spamming.

Thank you!