Unfortunately for websocket connections, additional headers and custom ones are not supported1 by most2 websocket clients and servers.
So the possible options are:
Cons: It could be vulnerable as it may end up in logs and system process information available to others that have access to the server, more here
Solution: Encrypt the token and attach it, so even if it can be seen in the logs, it would serve no purpose until its decrypted.
- Attach JWT in one of the allowed parameters.
Client side:
# Append jwt to protocols
new WebSocket(url, existing_protocols.concat(jwt))
I created a JS library action-cable-react-jwt for React
and React-Native
that just does this. Feel free to use it.
Server side:
# get the user by
# self.current_user = find_verified_user
def find_verified_user
begin
header_array = self.request.headers[:HTTP_SEC_WEBSOCKET_PROTOCOL].split(',')
token = header_array[header_array.length-1]
decoded_token = JWT.decode token, Rails.application.secrets.secret_key_base, true, { :algorithm => 'HS256' }
if (current_user = User.find((decoded_token[0])['sub']))
current_user
else
reject_unauthorized_connection
end
rescue
reject_unauthorized_connection
end
end
1 Most Websocket APIs (including Mozilla's) are just like the one below:
The WebSocket constructor accepts one required and one optional
parameter:
WebSocket WebSocket(
in DOMString url,
in optional DOMString protocols
);
WebSocket WebSocket(
in DOMString url,
in optional DOMString[] protocols
);
url
The URL to which to connect; this should be the URL to which the
WebSocket server will respond.
protocols
Optional
Either a single protocol string or an array of protocol strings. These
strings are used to indicate sub-protocols, so that a single server
can implement multiple WebSocket sub-protocols (for example, you might
want one server to be able to handle different types of interactions
depending on the specified protocol). If you don't specify a protocol
string, an empty string is assumed.
2 There are always excpetions, for instance, this node.js lib ws allows building custom headers, so you can use the usual Authorization: Bearer token
header, and parse it on the server but both client and server should use ws
.