Hidden connection spawning

[Mikkel Fahnøe Jørgensen <[e-mail]>]

I came to think about a use case where you want to spawn a new connection
from an existing connection because the new connection runs a different
protocol. For example a http connection where you  want to run a separate
live conference call, or to control tunnels from http control connection.

You have roughly three options:

1. extend the current protocol with the new feature set in extension frames
or similar
2. develop or use a purposes specific QUIC protol using 0-RTT for spawning
the connection
3. negotiate the new connection handshake within the current handshake.

The first solution is not complex, limited, and not modular.
The second solution can be used to get information about the connection,
and for example block connections that appear to be doing that.
The third solution allows for an invisible connection spawn, but requires
addition handshake logic which is already complex as it is.

I suggesting solution 3 as possible option, although I am not convinced
that this is worthwhile, at least in V1.


This was in part inspired by recent discussion on tunneling, and in part by
the following issue where partial reliability is being discussed and
possibly shoe-horned into an extension. I am not following that issue
closely though - it is just an example.
https://github.com/quicwg/base-drafts/issues/1606#issuecomment-407951495


Mikkel