HTTP headers in Websockets client API

Looks like it's easy to add custom HTTP headers to your websocket client with any HTTP header client which supports this, but I can't find how to do it with the web platform's WebSocket API.

Anyone has a clue on how to achieve it?

var ws = new WebSocket("ws://example.com/service");

Specifically, I need to be able to send an HTTP Authorization header.

Updated 2x

Short answer: No, only the path and protocol field can be specified.

Longer answer:

There is no method in the JavaScript WebSockets API for specifying additional headers for the client/browser to send. The HTTP path ("GET /xyz") and protocol header ("Sec-WebSocket-Protocol") can be specified in the WebSocket constructor.

The Sec-WebSocket-Protocol header (which is sometimes extended to be used in websocket specific authentication) is generated from the optional second argument to the WebSocket constructor:

var ws = new WebSocket("ws://example.com/path", "protocol");
var ws = new WebSocket("ws://example.com/path", ["protocol1", "protocol2"]);

The above results in the following headers:

Sec-WebSocket-Protocol: protocol

and

Sec-WebSocket-Protocol: protocol1, protocol2

A common pattern for achieving WebSocket authentication/authorization is to implement a ticketing system where the page hosting the WebSocket client requests a ticket from the server and then passes this ticket during WebSocket connection setup either in the URL/query string, in the protocol field, or required as the first message after the connection is established. The server then only allows the connection to continue if the ticket is valid (exists, has not been already used, client IP encoded in ticket matches, timestamp in ticket is recent, etc). Here is a summary of WebSocket security information: https://devcenter.heroku.com/articles/websocket-security

Basic authentication was formerly an option but this has been deprecated and modern browsers don't send the header even if it is specified.

Basic Auth Info (Deprecated - No longer functional):

> NOTE: the following information is no longer accurate in any modern browsers.

The Authorization header is generated from the username and password (or just username) field of the WebSocket URI:

var ws = new WebSocket("ws://username:[email protected]")

The above results in the following header with the string "username:password" base64 encoded:

Authorization: Basic dXNlcm5hbWU6cGFzc3dvcmQ=

I have tested basic auth in Chrome 55 and Firefox 50 and verified that the basic auth info is indeed negotiated with the server (this may not work in Safari).

Thanks to Dmitry Frank's for the basic auth answer

More of an alternate solution, but all modern browsers send the domain cookies along with the connection, so using:

var authToken = 'R3YKZFKBVi';

document.cookie = 'X-Authorization=' + authToken + '; path=/';

var ws = new WebSocket(
    'wss://localhost:9000/wss/'
);

End up with the request connection headers:

Cookie: X-Authorization=R3YKZFKBVi

HTTP Authorization header problem can be addressed with the following:

var ws = new WebSocket("ws://username:[email protected]/service");

Then, a proper Basic Authorization HTTP header will be set with the provided username and password. If you need Basic Authorization, then you're all set.

---

I want to use Bearer however, and I resorted to the following trick: I connect to the server as follows:

var ws = new WebSocket("ws://[email protected]/service");

And when my code at the server side receives Basic Authorization header with non-empty username and empty password, then it interprets the username as a token.

Sending Authorization header is not possible.

Attaching a token query parameter is an option. However, in some circumstances, it may be undesirable to send your main login token in plain text as a query parameter because it is more opaque than using a header and will end up being logged whoknowswhere. If this raises security concerns for you, an alternative is to use a secondary JWT token just for the web socket stuff.

Create a REST endpoint for generating this JWT, which can of course only be accessed by users authenticated with your primary login token (transmitted via header). The web socket JWT can be configured differently than your login token, e.g. with a shorter timeout, so it's safer to send around as query param of your upgrade request.

Create a separate JwtAuthHandler for the same route you register the SockJS eventbusHandler on. Make sure your auth handler is registered first, so you can check the web socket token against your database (the JWT should be somehow linked to your user in the backend).

You can not send custom header when you want to establish WebSockets connection using JavaScript WebSockets API. You can use Subprotocols headers by using the second WebSocket class constructor:

var ws = new WebSocket("ws://example.com/service", "soap");

and then you can get the Subprotocols headers using Sec-WebSocket-Protocol key on the server.

There is also a limitation, your Subprotocols headers values can not contain a comma (,) !

You cannot add headers but, if you just need to pass values to the server at the moment of the connection, you can specify a query string part on the url:

var ws = new WebSocket("ws://example.com/service?key1=value1&key2=value2");

That URL is valid but - of course - you'll need to modify your server code to parse it.

For those still struggling in 2021, Node JS global web sockets class has an additional options field in the constructor. if you go to the implementation of the the WebSockets class, you will find this variable declaration. You can see it accepts three params url, which is required, protocols(optional), which is either a string, an array of strings or null. Then a third param which is options. our interest, an object and (still optional). see ...

declare var WebSocket: {
    prototype: WebSocket;
    new (
        uri: string,
        protocols?: string | string[] | null,
        options?: {
            headers: { [headerName: string]: string };
            [optionName: string]: any;
        } | null,
    ): WebSocket;
    readonly CLOSED: number;
    readonly CLOSING: number;
    readonly CONNECTING: number;
    readonly OPEN: number;
};

If you are using a Node Js library like react , react-native. here is an example of how you can do it.

 const ws = new WebSocket(WEB_SOCKETS_URL, null, {
    headers: {
      ['Set-Cookie']: cookie,
    },
  });

Notice for the protocols I have passed null. If you are using jwt, you can pass the Authorisation header with Bearer + token

Disclaimer, this might not be supported by all browsers outside the box, from the MDN web docs you can see only two params are documented. see https://developer.mozilla.org/en-US/docs/Web/API/WebSocket/WebSocket#syntax

Totally hacked it like this, thanks to kanaka's answer.

Client:

var ws = new WebSocket(
    'ws://localhost:8080/connect/' + this.state.room.id, 
    store('token') || cookie('token') 
);

Server (using Koa2 in this example, but should be similar wherever):

var url = ctx.websocket.upgradeReq.url; // can use to get url/query params
var authToken = ctx.websocket.upgradeReq.headers['sec-websocket-protocol'];
// Can then decode the auth token and do any session/user stuff...

In my situation (Azure Time Series Insights wss://)

Using the ReconnectingWebsocket wrapper and was able to achieve adding headers with a simple solution:

socket.onopen = function(e) {
    socket.send(payload);
};

Where payload in this case is:

{
  "headers": {
    "Authorization": "Bearer TOKEN",
    "x-ms-client-request-id": "CLIENT_ID"
}, 
"content": {
  "searchSpan": {
    "from": "UTCDATETIME",
    "to": "UTCDATETIME"
  },
"top": {
  "sort": [
    {
      "input": {"builtInProperty": "$ts"},
      "order": "Asc"
    }], 
"count": 1000
}}}

to all future debugger - until today i.e 15-07-21

Browser also don't support sending customer headers to the server, so any such code

    import * as sock from 'websocket'
    const headers = {
        Authorization: "bearer " + token
    };
    console.log(headers);

    const wsclient = new sock.w3cwebsocket(
        'wss://' + 'myserver.com' + '/api/ws',
        '',
        '',
        headers,
        null
    );

This is not going to work in browser. The reason behind that is browser native Websocket constructor does not accept headers.

You can easily get misguided because w3cwebsocket contractor accepts headers as i have shown above. This works in node.js however.

You can pass the headers as a key-value in the third parameter (options) inside an object. Example with Authorization token. Left the protocol (second parameter) as null

ws = new WebSocket(‘ws://localhost’, null, { headers: { Authorization: token }})

Edit: Seems that this approach only works with nodejs library not with standard browser implementation. Leaving it because it might be useful to some people.

My case:

• I want to connect to a production WS server a www.mycompany.com/api/ws...
• using real credentials (a session cookie)...
• from a local page (localhost:8000).

Setting document.cookie = "sessionid=foobar;path=/" won't help as domains don't match.

The solution:

Add 127.0.0.1 wsdev.company.com to /etc/hosts.

This way your browser will use cookies from mycompany.com when connecting to www.mycompany.com/api/ws as you are connecting from a valid subdomain wsdev.company.com.

Technically, you will be sending these headers through the connect function before the protocol upgrade phase. This worked for me in a nodejs project:

var WebSocketClient = require('websocket').client;
var ws = new WebSocketClient();
ws.connect(url, '', headers);