Unhandled 'error' event about engine.io

[nicokaiser]

The "reserved fields must be empty" message is emitted by ws when a client sends invalid WebSocket data. We experience this to happen quite often, don't know if the reverse proxy or broken clients (or both) are the culprit.

So this error is very common in real life environments (and thus not an error rather a "invalid client request") so it should not kill the whole server.

Do you have an 'error' handler for your socket objects? Like this:

server.on('connection', function (socket) {
  socket.on('message', function () { ... });
  socket.on('close', function () { ... });
  socket.on('error', function (err) {
    debug('socket error: ', err); // or just do nothing
  });
});

[mmastrac]

Unfortunately that doesn't fix things - the error is an unhandled event emitted from the transport. I could try adding an error handler to the transport to patch around this, but I think there is a bug underlying this.

[rauchg]

@mmastrac I see what you mean now. error must be firing twice on the transport right?

[mmastrac]

@guille Correct - and it throws an unhandled exception the second time.

[rauchg]

Yep because we detach the error event.

[rauchg]

So this is an easy fix

[mmastrac]

Great- if you have a suggested patch, I can test it out with our load test. Thanks!

[rauchg]

Please test with master