On Tue, Nov 14, 2017 at 6:57 PM, Ed Swierk <eswi...@skyportsystems.com> wrote:
> diff --git a/hw/net/net_tx_pkt.c b/hw/net/net_tx_pkt.c
> index 20b2549..dc95f12 100644
> --- a/hw/net/net_tx_pkt.c
> +++ b/hw/net/net_tx_pkt.c
> @@ -126,12 +126,12 @@ void net_tx_pkt_update_ip_checksums(struct NetTxPkt
> *pkt)
>
> /* Calculate IP pseudo header checksum */
> cntr = eth_calc_ip4_pseudo_hdr_csum(ip_hdr, pkt->payload_len, &cso);
> - csum = cpu_to_be16(~net_checksum_finish(cntr));
> + csum = cpu_to_be16(~net_checksum_finish_hdr(cntr));
> } else if (gso_type == VIRTIO_NET_HDR_GSO_TCPV6) {
> /* Calculate IP pseudo header checksum */
> cntr = eth_calc_ip6_pseudo_hdr_csum(ip_hdr, pkt->payload_len,
> IP_PROTO_TCP, &cso);
> - csum = cpu_to_be16(~net_checksum_finish(cntr));
> + csum = cpu_to_be16(~net_checksum_finish_hdr(cntr));
> } else {
> return;
> }
Actually this change looks wrong. The checksum here is just the
partial sum of the IP pseudo-header fields, to be incorporated into
the actual UDP or TCP checksum (including the packet payload) at some
later stage. The partial sum should never be zero (if
net_rx_pkt_fix_l4_csum() is to be believed), but changing 0x0000 to
0xFFFF and then storing the complement ensures just that.
Unless someone with more of a clue says otherwise, I'll drop this change in v3.
--Ed
