Retry packet and PADDING

[larseggert]

-08 in Section 5.4.2. says:

The payload of the Retry packet contains a single STREAM frame on
stream 0 with offset 0 containing the server's cryptographic
stateless retry material. It MUST NOT contain any other frames. The
next STREAM frame sent by the server will also start at stream offset
0.

Any reason why PADDING is not allowed? (Insert usual stuff about zero-copy and fixed offsets.)

[marten-seemann]

There’s a related PR for this: #882

[larseggert]

#882 says "It SHOULD also contain an ACK frame" and removes the limit on any other frames. That looks a bit too broad?

Why not say "MAY contain PADDING (and ACK?) and MUST NOT..."

[MikeBishop]

#882 doesn't say anything about PADDING, and should perhaps also pad to the minimum handshake packet size (so it fails quickly if the network won't work). We should get this as part of updating it to cover #627.