The [WebSockets spec](https://www.rfc-editor.org/rfc/rfc6455) states
that text messages must be valid UTF-8 encoded strings, which protobuf
messages virtually never are. This now correctly sends the protobuf events
as binary messages.
We change the format to correspond to CloudEvents, as originally intended,
and remove a redundant timestamp and newline.
We also bump the eventlogger to fix a race condition that this code triggers.
This checks the request against the `read` permission for
`sys/events/subscribe/{eventType}` on the initial subscribe.
Future work includes moving this to its own verb (`subscribe`)
and periodically rechecking the request.
Tested locally by minting a token with the wrong permissions
and verifying that they are rejected as expected, and that
they work if the policy is adjusted to `sys/event/subscribe/*`
(or the specific topic name) with `read` permissions.
I had to change the `core.checkToken()` to be publicly accessible,
as it seems like the easiest way to check the token on the
`logical.Request` against all relevant policies, but without
going into all of the complex logic further in `handleLogical()`.
Co-authored-by: Tom Proctor <tomhjp@users.noreply.github.com>
Also updates the event receieved to include a timestamp.
Websockets support both JSON and protobuf binary formats.
This can be used by either `wscat` or the new
`vault events subscribe`:
e.g.,
```sh
$ wscat -H "X-Vault-Token: $(vault print token)" --connect ws://127.0.0.1:8200/v1/sys/events/subscribe/abc?json=true
{"event":{"id":"5c5c8c83-bf43-7da5-fe88-fc3cac814b2e", "note":"testing"}, "eventType":"abc", "timestamp":"2023-02-07T18:40:50.598408Z"}
...
```
and
```sh
$ vault events subscribe abc
{"event":{"id":"5c5c8c83-bf43-7da5-fe88-fc3cac814b2e", "note":"testing"}, "eventType":"abc", "timestamp":"2023-02-07T18:40:50.598408Z"}
...
```
Co-authored-by: Tom Proctor <tomhjp@users.noreply.github.com>
