On Tue, Jun 13, 2023 at 8:03 AM Willem de Bruijn
<willemdebruijn.kernel@xxxxxxxxx> wrote:
>
> On Mon, Jun 12, 2023 at 7:26 PM Stanislav Fomichev <sdf@xxxxxxxxxx> wrote:
> >
> > When we get packets on port 9091, we swap src/dst and send it out.
> > At this point, we also request the timestamp and plumb it back
> > to the userspace. The userspace simply prints the timestamp.
> >
> > Haven't really tested, still working on mlx5 patches...
> >
> > Cc: netdev@xxxxxxxxxxxxxxx
> > Signed-off-by: Stanislav Fomichev <sdf@xxxxxxxxxx>
>
>
> > +++ b/tools/testing/selftests/bpf/xdp_hw_metadata.c
> > @@ -10,7 +10,8 @@
> > * - rx_hash
> > *
> > * TX:
> > - * - TBD
> > + * - UDP 9091 packets trigger TX reply
>
> This branch on port is missing?
That's the ping_pong part. Evey packet arriving on 9091 port gets
received by af_xdp and is sent back.
> > +static void ping_pong(struct xsk *xsk, void *rx_packet)
> > +{
> > + struct ipv6hdr *ip6h = NULL;
> > + struct iphdr *iph = NULL;
> > + struct xdp_desc *tx_desc;
> > + struct udphdr *udph;
> > + struct ethhdr *eth;
> > + void *data;
> > + __u32 idx;
> > + int ret;
> > + int len;
> > +
> > + ret = xsk_ring_prod__reserve(&xsk->tx, 1, &idx);
> > + if (ret != 1) {
> > + printf("%p: failed to reserve tx slot\n", xsk);
> > + return;
> > + }
> > +
> > + tx_desc = xsk_ring_prod__tx_desc(&xsk->tx, idx);
> > + tx_desc->addr = idx % (UMEM_NUM / 2) * UMEM_FRAME_SIZE;
> > + data = xsk_umem__get_data(xsk->umem_area, tx_desc->addr);
> > +
> > + eth = data;
> > +
> > + if (eth->h_proto == htons(ETH_P_IP)) {
> > + iph = (void *)(eth + 1);
> > + udph = (void *)(iph + 1);
> > + } else if (eth->h_proto == htons(ETH_P_IPV6)) {
> > + ip6h = (void *)(eth + 1);
> > + udph = (void *)(ip6h + 1);
> > + } else {
> > + xsk_ring_prod__cancel(&xsk->tx, 1);
> > + return;
> > + }
> > +
> > + len = ETH_HLEN;
> > + if (ip6h)
> > + len += ntohs(ip6h->payload_len);
>
> sizeof(*ip6h) + ntohs(ip6h->payload_len) ?
Ooop, thanks, that's clearly not tested :-)
> > + if (iph)
> > + len += ntohs(iph->tot_len);
> > +
> > + memcpy(data, rx_packet, len);
> > + swap(eth->h_dest, eth->h_source, ETH_ALEN);
> > + if (iph)
> > + swap(&iph->saddr, &iph->daddr, 4);
>
> need to recompute ipv4 checksum?
Discussed offline: swapping the aligned-u16 chunks preserves the checksum.
