Re: [RFC 0/2] Delayed binding of UDP sockets for Quic per-connection sockets

[Christoph Paasch <cpaasch@apple.com>]

On 01/11/18 - 17:51:39, Willem de Bruijn wrote:
> On Wed, Oct 31, 2018 at 7:30 PM Christoph Paasch <cpaasch@apple.com> wrote:
> >
> > Implementations of Quic might want to create a separate socket for each
> > Quic-connection by creating a connected UDP-socket.
> >
> > To achieve that on the server-side, a "master-socket" needs to wait for
> > incoming new connections and then creates a new socket that will be a
> > connected UDP-socket. To create that latter one, the server needs to
> > first bind() and then connect(). However, after the bind() the server
> > might already receive traffic on that new socket that is unrelated to the
> > Quic-connection at hand.
> 
> This can also be achieved with SO_REUSEPORT_BPF and a filter
> that only selects the listener socket(s) in the group. The connect
> call should call udp_lib_rehash and take the connected socket out
> of the reuseport listener group. Though admittedly that is more
> elaborate than setting a boolean socket option.

Yeah, that indeed would be quite a bit more elaborate ;-)

A simple socket-option is much easier.


Cheers,
Christoph

> 
> > The ideas for the implementation came up after a discussion with Ian
> > and Jana re: their implementation of a QUIC server.
> 
> That might have preceded SO_TXTIME? AFAIK traffic shaping was the
> only real reason to prefer connected sockets.