Any other transport protocol for LibVNC?

[NooshinEghbal]

Hi,

I was wondering if LibVNC could run over any other protocols like QUIC/UDT to avoid the Head-of-Line blocking problem of TCP?

Thanks,
Nooshin

[bk138]

Possibly, but that probably would need some/lotsof work. You can, however, have a look at https://github.com/LibVNC/libvncserver/tree/multicastvnc which uses UDP multicast for the image data.

[NooshinEghbal]

Thanks.
I looked into multicastvnc/libvncserver/sockets.c and found where the UDP socket created.
But I could not find how you managed reliability using UDP. In other words, in the case of packet loss, how you know to resend it?

[bk138]

Thanks. I looked into multicastvnc/libvncserver/sockets.c and found where the UDP socket created. But I could not find how you managed reliability using UDP. In other words, in the case of packet loss, how you know to resend it?

There's an overview here and an in-depth discussion here.

[RokerHRO]

But I could not find how you managed reliability using UDP. In other words, in the case of packet loss, how you know to resend it?

It is the very nature of UDP that packets can be lost without the whole system would collaps. And multicast also does not allow re-sending to individual recepients, because the server does not know who listens to it.

In other words: The chosen odecs must be fault tolerant, fit into one UDP packet and I'd say also more often non-incremental screen updates might be necessary to recover quickly from display artifacts caused by loss packets.

I'd favour VNC-over-RTP, so also an RTCP channel exists where clients can report "channel quality" information back to the server.

[bk138]

Let's consider this a dupe of #394 (which has some fault tolerance built into it).