javascripthttpheaderwebsocket

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.

Solution

  • 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:password@example.com")

    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