How to return custom error code if onSubscribe throws an error ?

[97amarnathk]

Use Case

I am using graphql-ws with authToken which can expire. Incase the token expires when a client sends some graphql operation, I need to disconnect the socket and reconnect again.

My approach

1. On each subscription event from the client, I am passing the authToken in the SubscriptionPayload
2. onSubscribe validates the authToken , and if it has expired , it throws a new Error("token invalid"). Reference example: https://github.com/enisdenjo/graphql-ws#ws-auth-handling
3. In the client I am planning to add an isFatalConnectionProblem hook. Here I will see if the error has reason "token invalid", get a new authToken, and retry again with this authToken.

Problem

Because of an error code check in client.ts, returning the "token invalid" error from onSubscribe, the websocket error code is 1011. Because of which isFatalConnectionProblem is not being called, and as a result the retry does not take place.

How do I throw a non 1011 error code to the client, if onSubscribe fails, so that I can retry connection?

[enisdenjo]

Answered in full detail here: #166 (reply in thread).

TL;DR to close the socket manually with whatever close event you wish, you simply use the socket in the context. Something like context.extra.socket.close(4401, 'Unauthorized').

[97amarnathk]

you can just have a flag that is something like serverClosedBecauseUnauthorized and set it to true once the close event matches the unauthorized close event dispatched by the server.

How would I share this flag serverClosedBecauseUnauthorized between the 2 hooks isFatalConnectionProblem and connectionParams ?

[enisdenjo]

But an edge case is when the authToken is valid according to the client, but has been revoked/cancelled by the server (because of some other feature like force logout for users etc.)

A valid point.

How would I share this flag serverClosedBecauseUnauthorized between the 2 hooks isFatalConnectionProblem and connectionParams ?

Easy, just use JavaScript:

import { createClient } from 'graphql-ws';
import { getCurrentToken, refreshCurrentToken } from './my-auth';

// indicates that the server closed the connection because of
// an auth problem. it indicates that the token should refresh
let shouldRefreshToken = false;

const client = createClient({
  url: 'ws://server-closed.because/unauthorized',
  connectionParams: async () => {
    if (shouldRefreshToken) {
      // refresh the token because it is no longer valid
      await refreshCurrentToken();
      // and reset the flag to avoid refreshing too many times
      shouldRefreshToken = false;
    }
    return { token: getCurrentToken() };
  },
  on: {
    closed: (event) => {
      // if closed with the `4401: Unauthorized` close event
      // server is communicating that the token is no longer
      // valid and should be therefore refreshed
      if (event.code === 4401) shouldRefreshToken = true;
    },
  },
});

[enisdenjo]

Hey @97amarnathk, I've added a new recipe showcasing ws server and client auth usage with token expiration, validation and refresh. I sure hope it helps you get the concept described in our recent discussions.

[97amarnathk]

Yes. Thanks a lot!
Works nicely. Only thing is 4401 too is a reserved code by graphql-ws, so is not retryable.

I am using 4430

[enisdenjo]

My bad! I changed the example to use 4403: Forbidden instead.

Furthermore, I recommend using 4403 because returning false from onConnect automatically closes the connection with a 4403: Forbidden.