Re: [Qemu-devel] [RFC PATCH 3/3] filter-rewriter: rewrite tcp packet to keep secondary connection

[Zhang Chen]

On 06/29/2016 09:55 AM, Jason Wang wrote:
> On 2016年06月28日 14:33, Zhang Chen wrote:
> > > > > > primary guest response 
> > > > > > pkt(seq=primary_seq+1,ack=client_seq+1+data_len,flag=ACK)
> > > > > > secondary guest response 
> > > > > > pkt(seq=secondary_seq+1,ack=client_seq+1+data_len,flag=ACK)
> > > > >
> > > > > Is ACK a must here?
> > > >
> > > > Yes.
> > >
> > > Looks not, e.g what happens if guest does not use piggybacking acks?
> >
> > If guest does not use piggybacking acks, it will send a independent 
> > packet for ack.
> > we will get this packet.
> > like:
> > pkt(seq=xxxx,ack=xxx,flag=ACK). 
>
> Right, so looks like if guest want to send some data too, it can send 
> tcp packet without ACK set?

NO, I tried it. the tcp packet always has ACK set except the SYN packet 
and FIN packet.
you can dump the packet to see it.

Thanks
Zhang Chen

>

--
Thanks
zhangchen