Socket handshake data before proxying the websocket request

Hi, Can we get the data sent along handshake as well before proxying websocket request? like on proxyreqws event

proxy.on('proxyReqWs', (proxyReq, req, socket, options, head) => {
    //before the request is actually proxyed to the target server
    //access socket handshake data like sent via low level params like query and auth
});

Although we can get the query params from url, how to get the auth sent along with handshake request? If we haven't added the option of polling in transport, still initially the upgrade request is an http request. So the handshake request will be an an http request. How to get the data then?