[Qemu-devel] [PATCH V6 02/10] net/filter-mirror.c: Make filter mirror support vnet support.

[Zhang Chen <zhangchen.fnst@cn.fujitsu.com>]

We add the vnet_hdr_support option for filter-mirror, default is disable.
If you use virtio-net-pci net driver, please enable it.
You can use it for example:
-object filter-mirror,id=m0,netdev=hn0,queue=tx,outdev=mirror0,vnet_hdr_support

If have vnet_hdr_support flag, we will 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.fnst@cn.fujitsu.com>
---
 net/filter-mirror.c | 69 +++++++++++++++++++++++++++++++++++++++++++++++++----
 qemu-options.hx     |  5 ++--
 2 files changed, 66 insertions(+), 8 deletions(-)

diff --git a/net/filter-mirror.c b/net/filter-mirror.c
index 72fa7c2..50aa81b 100644
--- a/net/filter-mirror.c
+++ b/net/filter-mirror.c
@@ -38,15 +38,17 @@ typedef struct MirrorState {
     NetFilterState parent_obj;
     char *indev;
     char *outdev;
+    bool vnet_hdr;
     CharBackend chr_in;
     CharBackend chr_out;
     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;
     uint32_t len = 0;
@@ -58,14 +60,43 @@ 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;
     }
 
+    if (s->vnet_hdr) {
+        /*
+         * If vnet_hdr = on, we send vnet header len to make other
+         * module(like colo-compare) know how to parse net
+         * packet correctly.
+         */
+        ssize_t vnet_hdr_len;
+
+        /*
+         * 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.
+         */
+        if (nf->direction == NET_FILTER_DIRECTION_RX ||
+            nf->direction == NET_FILTER_DIRECTION_ALL) {
+            vnet_hdr_len = nf->netdev->vnet_hdr_len;
+        } else if (nf->direction == NET_FILTER_DIRECTION_TX) {
+            vnet_hdr_len = nf->netdev->peer->vnet_hdr_len;
+        } else {
+            return 0;
+        }
+
+        len = htonl(vnet_hdr_len);
+        ret = qemu_chr_fe_write_all(&s->chr_out, (uint8_t *)&len, sizeof(len));
+        if (ret != sizeof(len)) {
+            goto err;
+        }
+    }
+
     buf = g_malloc(size);
     iov_to_buf(iov, iovcnt, 0, buf, size);
-    ret = qemu_chr_fe_write_all(chr_out, (uint8_t *)buf, size);
+    ret = qemu_chr_fe_write_all(&s->chr_out, (uint8_t *)buf, size);
     g_free(buf);
     if (ret != size) {
         goto err;
@@ -141,7 +172,7 @@ static ssize_t filter_mirror_receive_iov(NetFilterState *nf,
     MirrorState *s = FILTER_MIRROR(nf);
     int ret;
 
-    ret = filter_mirror_send(&s->chr_out, iov, iovcnt);
+    ret = filter_mirror_send(s, iov, iovcnt);
     if (ret) {
         error_report("filter_mirror_send failed(%s)", strerror(-ret));
     }
@@ -164,7 +195,7 @@ static ssize_t filter_redirector_receive_iov(NetFilterState *nf,
     int ret;
 
     if (qemu_chr_fe_get_driver(&s->chr_out)) {
-        ret = filter_mirror_send(&s->chr_out, iov, iovcnt);
+        ret = filter_mirror_send(s, iov, iovcnt);
         if (ret) {
             error_report("filter_mirror_send failed(%s)", strerror(-ret));
         }
@@ -308,6 +339,13 @@ static char *filter_mirror_get_outdev(Object *obj, Error **errp)
     return g_strdup(s->outdev);
 }
 
+static bool filter_mirror_get_vnet_hdr(Object *obj, Error **errp)
+{
+    MirrorState *s = FILTER_MIRROR(obj);
+
+    return s->vnet_hdr;
+}
+
 static void
 filter_mirror_set_outdev(Object *obj, const char *value, Error **errp)
 {
@@ -322,6 +360,15 @@ filter_mirror_set_outdev(Object *obj, const char *value, Error **errp)
     }
 }
 
+static void filter_mirror_set_vnet_hdr(Object *obj,
+                                       bool value,
+                                       Error **errp)
+{
+    MirrorState *s = FILTER_MIRROR(obj);
+
+    s->vnet_hdr = value;
+}
+
 static char *filter_redirector_get_outdev(Object *obj, Error **errp)
 {
     MirrorState *s = FILTER_REDIRECTOR(obj);
@@ -340,8 +387,20 @@ filter_redirector_set_outdev(Object *obj, const char *value, Error **errp)
 
 static void filter_mirror_init(Object *obj)
 {
+    MirrorState *s = FILTER_MIRROR(obj);
+
     object_property_add_str(obj, "outdev", filter_mirror_get_outdev,
                             filter_mirror_set_outdev, NULL);
+
+    /*
+     * The vnet_hdr is disabled by default, if you want to enable
+     * this option, you must enable all the option on related modules
+     * (like other filter or colo-compare).
+     */
+    s->vnet_hdr = false;
+    object_property_add_bool(obj, "vnet_hdr_support",
+                             filter_mirror_get_vnet_hdr,
+                             filter_mirror_set_vnet_hdr, NULL);
 }
 
 static void filter_redirector_init(Object *obj)
diff --git a/qemu-options.hx b/qemu-options.hx
index 70c0ded..5c09fae 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -4024,10 +4024,9 @@ queue @var{all|rx|tx} is an option that can be applied to any netfilter.
 @option{tx}: the filter is attached to the transmit queue of the netdev,
              where it will receive packets sent by the netdev.
 
-@item -object filter-mirror,id=@var{id},netdev=@var{netdevid},outdev=@var{chardevid}[,queue=@var{all|rx|tx}]
+@item -object filter-mirror,id=@var{id},netdev=@var{netdevid},outdev=@var{chardevid},queue=@var{all|rx|tx}[,vnet_hdr_support]
 
-filter-mirror on netdev @var{netdevid},mirror net packet to chardev
-@var{chardevid}
+filter-mirror on netdev @var{netdevid},mirror net packet to chardev@var{chardevid}, if have the vnet_hdr_support flag, filter-mirror will mirror packet with vnet_hdr_len.
 
 @item -object filter-redirector,id=@var{id},netdev=@var{netdevid},indev=@var{chardevid},
 outdev=@var{chardevid}[,queue=@var{all|rx|tx}]
-- 
2.7.4