Re: [Qemu-devel] [PATCH V6 09/10] net/filter-rewriter.c: Make filter-rewriter support vnet_hdr_len

[Jason Wang <jasowang@redhat.com>]

On 2017年06月07日 17:55, Zhang Chen wrote:
> We add the vnet_hdr_support option for filter-rewriter, default is disable.
> If you use virtio-net-pci net driver, please enable it.
> You can use it for example:
> -object filter-rewriter,id=rew0,netdev=hn0,queue=all,vnet_hdr_support
>
> We get the vnet_hdr_len from NetClientState that make us
> parse net packet correctly.
>
> Signed-off-by: Zhang Chen <zhangchen.fnst@cn.fujitsu.com>
> ---
>   net/filter-rewriter.c | 51 ++++++++++++++++++++++++++++++++++++++++++++++++++-
>   qemu-options.hx       |  4 ++--
>   2 files changed, 52 insertions(+), 3 deletions(-)
>
> diff --git a/net/filter-rewriter.c b/net/filter-rewriter.c
> index 63256c7..8eaf0e8 100644
> --- a/net/filter-rewriter.c
> +++ b/net/filter-rewriter.c
> @@ -17,6 +17,7 @@
>   #include "qemu-common.h"
>   #include "qapi/error.h"
>   #include "qapi/qmp/qerror.h"
> +#include "qemu/error-report.h"
>   #include "qapi-visit.h"
>   #include "qom/object.h"
>   #include "qemu/main-loop.h"
> @@ -33,6 +34,7 @@ typedef struct RewriterState {
>       NetQueue *incoming_queue;
>       /* hashtable to save connection */
>       GHashTable *connection_track_table;
> +    bool vnet_hdr;
>   } RewriterState;
>   
>   static void filter_rewriter_flush(NetFilterState *nf)
> @@ -155,10 +157,25 @@ static ssize_t colo_rewriter_receive_iov(NetFilterState *nf,
>       ConnectionKey key;
>       Packet *pkt;
>       ssize_t size = iov_size(iov, iovcnt);
> +    ssize_t vnet_hdr_len = 0;
>       char *buf = g_malloc0(size);
>   
>       iov_to_buf(iov, iovcnt, 0, buf, size);
> -    pkt = packet_new(buf, size, 0);
> +
> +    if (s->vnet_hdr) {
> +        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 {
> +            error_report("filter-rewriter get vnet_hdr_len failed");
> +            /* When error occurred we drop the packet  */
> +            return 1;
> +        }
> +    }

Similar issue as patch 02, and we can probably use a helper to avoid 
duplicating codes.

Thanks

> +
> +    pkt = packet_new(buf, size, vnet_hdr_len);
>       g_free(buf);
>   
>       /*
> @@ -237,6 +254,37 @@ static void colo_rewriter_setup(NetFilterState *nf, Error **errp)
>       s->incoming_queue = qemu_new_net_queue(qemu_netfilter_pass_to_next, nf);
>   }
>   
> +static bool filter_rewriter_get_vnet_hdr(Object *obj, Error **errp)
> +{
> +    RewriterState *s = FILTER_COLO_REWRITER(obj);
> +
> +    return s->vnet_hdr;
> +}
> +
> +static void filter_rewriter_set_vnet_hdr(Object *obj,
> +                                         bool value,
> +                                         Error **errp)
> +{
> +    RewriterState *s = FILTER_COLO_REWRITER(obj);
> +
> +    s->vnet_hdr = value;
> +}
> +
> +static void filter_rewriter_init(Object *obj)
> +{
> +    RewriterState *s = FILTER_COLO_REWRITER(obj);
> +
> +    /*
> +     * 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_rewriter_get_vnet_hdr,
> +                             filter_rewriter_set_vnet_hdr, NULL);
> +}
> +
>   static void colo_rewriter_class_init(ObjectClass *oc, void *data)
>   {
>       NetFilterClass *nfc = NETFILTER_CLASS(oc);
> @@ -250,6 +298,7 @@ static const TypeInfo colo_rewriter_info = {
>       .name = TYPE_FILTER_REWRITER,
>       .parent = TYPE_NETFILTER,
>       .class_init = colo_rewriter_class_init,
> +    .instance_init = filter_rewriter_init,
>       .instance_size = sizeof(RewriterState),
>   };
>   
> diff --git a/qemu-options.hx b/qemu-options.hx
> index fbfd604..8655842 100644
> --- a/qemu-options.hx
> +++ b/qemu-options.hx
> @@ -4037,12 +4037,12 @@ Create a filter-redirector we need to differ outdev id from indev id, id can not
>   be the same. we can just use indev or outdev, but at least one of indev or outdev
>   need to be specified.
>   
> -@item -object filter-rewriter,id=@var{id},netdev=@var{netdevid},rewriter-mode=@var{mode}[,queue=@var{all|rx|tx}]
> +@item -object filter-rewriter,id=@var{id},netdev=@var{netdevid},rewriter-mode=@var{mode},queue=@var{all|rx|tx},[vnet_hdr_support]
>   
>   Filter-rewriter is a part of COLO project.It will rewrite tcp packet to
>   secondary from primary to keep secondary tcp connection,and rewrite
>   tcp packet to primary from secondary make tcp packet can be handled by
> -client.
> +client.if have the vnet_hdr_support flag, we can parse packet with vnet header.
>   
>   usage:
>   colo secondary: