[Proposal] Close Websocket connections when the context is done/cancelled

[RobinCPel]

Scenario

What happened?

When the websocket's configured initialization function is ran, and returns a modified context with a deadline set to the expiration time of a JWT (JSON Web Token), the websocket is not disconnected when the context is done/cancelled.

What did you expect?

That the websocket would be disconnected.

Versions

• gqlgen version? v0.14.0
• go version? 1.17.3 darwin/amd64
• dep or go modules? Modules!

The Actual Proposal

Let the websocket connection close when the context is done.

Example

Add the following function to the wsConnection type:

func (c *wsConnection) closeOnCancel(ctx context.Context) {
	<-ctx.Done()
	c.close(websocket.CloseNormalClosure, "terminated")
}

And then, call it from the wsConnection's run function like so:

go c.closeOnCancel(ctx)

More feedback = more better

For this reason it would also be nice to add a way to communicate back to the user that the token has expired. Maybe through a context value like this?

// A private key for context that only this package can access. This is important
// to prevent collisions between different context uses
var closeReasonCtxKey = &wsCloseReasonContextKey{"close-reason"}
type wsCloseReasonContextKey struct {
	name string
}

func AppendCloseReason(ctx context.Context, reason string) context.Context {
	return context.WithValue(ctx, closeReasonCtxKey, reason)
}

func closeReasonForContext(ctx context.Context) string {
	reason, _ := ctx.Value(closeReasonCtxKey).(string)
	return reason
}

func (c *wsConnection) closeOnCancel(ctx context.Context) {
	<-ctx.Done()

	if r := closeReasonForContext(ctx); r != "" {
		c.sendConnectionError(r)
	}
	c.close(websocket.CloseNormalClosure, "terminated")
}

This way, the application can add a reason to the context values like so:

func WebsocketAuthorization(ctx context.Context, initPayload transport.InitPayload) (context.Context, error) {
	payloadAuth := initPayload.Authorization()
	if payloadAuth == "" {
		return ctx, errors.New("the JWT is missing in the initialization payload")
	}

	jwt, err := authenticateJWT(payloadAuth)
	if err != nil {
		return ctx, err
	}

	// Add the JWT expiration as a deadline, and add the reason
	newCtx, _ := context.WithDeadline(transport.AppendCloseReason(ctx, "authentication token has expired"), time.Unix(jwt.ExpiresAt, 0))
	return newCtx, nil
}

Sidenote

This proposal would also solve this (pretty old) issue #774.

[RobinCPel]

Implemented through this PR: #1728