[Qemu-devel] [RFC Patch v2 06/10] virtio-net rsc: IPv4 checksum

[wexu]

From: Wei Xu <address@hidden>

If a field in the IPv4 header is modified, then the checksum
have to be recalculated before sending it out.

Signed-off-by: Wei Xu <address@hidden>
---
 hw/net/virtio-net.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
index 93df0d5..88fc4f8 100644
--- a/hw/net/virtio-net.c
+++ b/hw/net/virtio-net.c
@@ -1630,6 +1630,18 @@ static int virtio_net_load_device(VirtIODevice *vdev, 
QEMUFile *f,
     return 0;
 }
 
+static void virtio_net_rsc_ipv4_checksum(NetRscSeg *seg)
+{
+    uint32_t sum;
+    struct ip_header *ip;
+
+    ip = (struct ip_header *)(seg->buf + IP_OFFSET);
+
+    ip->ip_sum = 0;
+    sum = net_checksum_add_cont(sizeof(struct ip_header), (uint8_t *)ip, 0);
+    ip->ip_sum = cpu_to_be16(net_checksum_finish(sum));
+}
+
 static void virtio_net_rsc_purge(void *opq)
 {
     int ret = 0;
@@ -1643,6 +1655,10 @@ static void virtio_net_rsc_purge(void *opq)
             continue;
         }
 
+        if ((chain->proto == ETH_P_IP) && seg->is_coalesced) {
+            virtio_net_rsc_ipv4_checksum(seg);
+        }
+
         ret = virtio_net_do_receive(seg->nc, seg->buf, seg->size);
         QTAILQ_REMOVE(&chain->buffers, seg, next);
         g_free(seg->buf);
@@ -1853,6 +1869,9 @@ static size_t virtio_net_rsc_callback(NetRscChain *chain, 
NetClientState *nc,
     QTAILQ_FOREACH_SAFE(seg, &chain->buffers, next, nseg) {
         ret = coalesce(chain, seg, buf, size);
         if (RSC_FINAL == ret) {
+            if ((chain->proto == ETH_P_IP) && seg->is_coalesced) {
+                virtio_net_rsc_ipv4_checksum(seg);
+            }
             ret = virtio_net_do_receive(seg->nc, seg->buf, seg->size);
             QTAILQ_REMOVE(&chain->buffers, seg, next);
             g_free(seg->buf);
-- 
2.4.0