Re: [RFC PATCH v3 00/11] qapi: net: add unix socket type support to netdev backend

[Laurent Vivier]

On 20/06/2022 20:24, Dr. David Alan Gilbert wrote:
> * Laurent Vivier (lvivier@redhat.com) wrote:
> > "-netdev socket" only supports inet sockets.
> >
> > It's not a complex task to add support for unix sockets, but
> > the socket netdev parameters are not defined to manage well unix
> > socket parameters.
> >
> > As discussed in:
> >
> >    "socket.c added support for unix domain socket datagram transport"
> >    
> > https://lore.kernel.org/qemu-devel/1C0E1BC5-904F-46B0-8044-68E43E67BE60@gmail.com/
> >
> > This series adds support of unix socket type using SocketAddress QAPI structure.
> >
> > Two new netdev backends, "stream" and "dgram" are added, that are barely a copy of 
> > "socket"
> > backend but they use the SocketAddress QAPI to provide socket parameters.
> > And then they also implement unix sockets (TCP and UDP).
>
> Had you considered a -netdev chardev?

I think by definition a "chardev" doesn't behave like a "netdev". Moreover "chardev" is 
already a frontend for several backends (socket, udp, ...), this would mean we use the 
frontend "chardev" as a backend of a "netdev". More and more layers...

And in the case of "-netdev dgram", we can use unix socket and sendto()/recv() while 
something like "-chardev udp,id=char0 -netdev chardev,chardev=char0,id=net0" doesn't 
support unix (see qio_channel_socket_dgram_sync()/socket_dgram()) and uses a 
"connect()/sendmsg()/recv()" (that really changes the behaviour of the backend)

The aim of this series is to add unix socket support.

Thanks,
Laurent