Re: [quicwg/base-drafts] Pad path validation in both directions (#4241)

[Jana Iyengar <[e-mail]>]

@janaiyengar commented on this pull request.



> +PATH_CHALLENGE was received.  This ensures the path is functional in both
+directions.  This requirement MUST NOT be enforced by the endpoint that

This justification could be a bit more precise.
```
This ensures that the peer's path validation succeeds only if the path is functional
in both directions.
```

>  frame unless constrained by congestion control.
 
+A PATH_RESPONSE frame SHOULD be sent on the network path where the
+PATH_CHALLENGE was received.  This ensures the path is functional in both
+directions.  This requirement MUST NOT be enforced by the endpoint that
+initiates path validation as that would enable an attack on migration; see
+{{off-path-forward}}.
+
+An endpoint SHOULD expand datagrams that contain a PATH_RESPONSE frame to at

Why is this optional?
```suggestion
An endpoint MUST expand datagrams that contain a PATH_RESPONSE frame to at
```

>  frame unless constrained by congestion control.
 
+A PATH_RESPONSE frame SHOULD be sent on the network path where the

We can require this from the endpoint, while at the same time requiring the peer to not enforce it. We've done unenforceable MUSTs in other parts of the specs. What is the justification for allowing this wiggle room?

```suggestion
A PATH_RESPONSE frame MUST be sent on the network path where the
```

-- 
You are receiving this because you are subscribed to this thread.
Reply to this email directly or view it on GitHub:
https://github.com/quicwg/base-drafts/pull/4241#pullrequestreview-512245928