GET webhooks/:webhookId/:webhookToken/messages/:msgId always returns 404

[Larsundso]

How to reproduce:

• Post a message with a webhook
• GET https://discord.com/api/v10/webhooks/:webhookId/:webhookToken/messages/:msgId
• GET https//localhost:8080/api/v10/webhooks/:webhookId/:webhookToken/messages/:msgId

Possible prerequisites

Every time i restarted the docker image it would work for 5-10 seconds before returning 404 again
The error description would be "No Description"
I encountered this only after releasing a Feature that would utilize several hundred webhooks sending several thousand requests per minute combined

[Larsundso]

I'm not sure what other webhook endpoints are affected, but DELETE webhook message is too

[Larsundso]

Fixed by restarting the docker container
Edited issue

[Zoddo]

@Larsundso I think you can reopen the issue because you found a bug.

I can repro reliably by trying to get a message that don't/no longer exists.

Repro steps:

1. Post a message using a valid webhook: curl -i -X POST -H 'Content-Type: application/json' http://nirn-proxy.prod.svc.cluster.local/api/webhooks/:id/:token?wait=true -d '{"content":"test"}'
2. Get the message, it should returns a 200: curl -i http://nirn-proxy.prod.svc.cluster.local/api/webhooks/:id/:token/messages/:id
3. Repeats step 2 with an invalid ID (do +1 in the message ID). You get a {"message": "404: Not Found", "code": 0} as expected.
4. Repeat step 2 again with the valid message ID. You now get a fake 404 "Unknown webhook" originating from nirn (as it can be seen with the missing CF's headers in the response).

The issue likely lies here:

nirn-proxy/lib/queue.go

Lines 351 to 358 in 23fc2e7

	if resp.StatusCode == 404 && strings.HasPrefix(path, "/webhooks/") && !isInteraction(item.Req.URL.String()) {
	logger.WithFields(logrus.Fields{
	"bucket": path,
	"route": item.Req.URL.String(),
	"method": item.Req.Method,
	}).Info("Setting fail fast 404 for webhook")
	ret404 = true
	}

It should additionally check if the body code is 10015 (Unknown webhook).

I looked to make a PR but I'm not sure how to parse the body and I'm not a go dev :(