Re: [Qemu-devel] [PATCH V3 04/10] net/filter-mirror.c: Add filter-mirror and filter-redirector vnet support.

[Zhang Chen]

On 05/05/2017 05:25 PM, Jason Wang wrote:


On 2017年05月05日 16:44, Zhang Chen wrote:


On 05/03/2017 06:19 PM, Jason Wang wrote:


On 2017年05月03日 11:18, Zhang Chen wrote:


On 05/02/2017 12:47 PM, Jason Wang wrote:


On 2017年04月28日 17:47, Zhang Chen wrote:
In this patch, we change the send packet format from
struct {int size; const uint8_t buf[];} to {int size; int 
vnet_hdr_len; const uint8_t buf[];}.
make other module(like colo-compare) know how to parse net packet 
correctly.

Signed-off-by: Zhang Chen <zhangchen.f...@cn.fujitsu.com>
---
  net/filter-mirror.c | 28 +++++++++++++++++++++++-----
  1 file changed, 23 insertions(+), 5 deletions(-)

diff --git a/net/filter-mirror.c b/net/filter-mirror.c
index 72fa7c2..bb9ecf3 100644
--- a/net/filter-mirror.c
+++ b/net/filter-mirror.c
@@ -43,12 +43,14 @@ typedef struct MirrorState {
      SocketReadState rs;
  } MirrorState;
  -static int filter_mirror_send(CharBackend *chr_out,
+static int filter_mirror_send(MirrorState *s,
                                const struct iovec *iov,
                                int iovcnt)
  {
+    NetFilterState *nf = NETFILTER(s);
      int ret = 0;
      ssize_t size = 0;
+    ssize_t vnet_hdr_len;
      uint32_t len = 0;
      char *buf;
  @@ -58,14 +60,30 @@ static int filter_mirror_send(CharBackend 
*chr_out,
      }
        len = htonl(size);
-    ret = qemu_chr_fe_write_all(chr_out, (uint8_t *)&len, 
sizeof(len));
+    ret = qemu_chr_fe_write_all(&s->chr_out, (uint8_t *)&len, 
sizeof(len));
+    if (ret != sizeof(len)) {
+        goto err;
+    }
+
+    /*
+     * We send vnet header len make other module(like colo-compare)
+     * know how to parse net packet correctly.
+     */
+    if (qemu_get_using_vnet_hdr(nf->netdev)) {
+        vnet_hdr_len = qemu_get_vnet_hdr_len(nf->netdev);
+    } else {
+        vnet_hdr_len = qemu_get_vnet_hdr_len(nf->netdev->peer);
+    }

Any reason to query peer here?

That's depend on using NetClientState, If we using nf->netdev that 
need to query,
Otherwise we query nf->netdev->peer, then we can get the real 
vnet_hdr_len in my test.

Thanks
Zhang Chen 

Confused, I think nf->netdev won't be a nic?

I don't know whether I fully understand.
I think it's depend on the sender, we must query sender to get real 
vnet_hdr_len ,
like that in filter.c:

        if (sender == nf->netdev) {
            /* This packet is sent by netdev itself */
            direction = NET_FILTER_DIRECTION_TX;
        } else {
            direction = NET_FILTER_DIRECTION_RX;
        }

Thanks
Zhang Chen

The problem is nf->netdev->peer should be a nic. But we don't care 
about its vnet_hdr_len. Take virtio-net as an example, we only care 
about host_hdr_len, since guest will strip the part that host does not 
care.

Yes, you are right. In anytime, nf->netdev and nf->netdev->peer both 
have a vnet_hdr_len,
Here we just find out which is we need. When filter set RX or TX that 
the real vnet_hdr_len are different.
We need query different netdev to get in my test.

Thanks
Zhang Chen


Thanks




Thanks


.





.


--
Thanks
Zhang Chen