Re: [Qemu-devel] [PATCH v2 2/3] net/filter.c: Add Options to insert filters anywhere in the filter list

[Zhang, Chen]

> -----Original Message-----
> From: Lukas Straub [mailto:address@hidden]
> Sent: Friday, August 16, 2019 2:49 AM
> To: qemu-devel <address@hidden>
> Cc: Zhang, Chen <address@hidden>; Jason Wang
> <address@hidden>; Wen Congyang <address@hidden>; Xie
> Changlong <address@hidden>
> Subject: [PATCH v2 2/3] net/filter.c: Add Options to insert filters anywhere 
> in
> the filter list
> 
> To switch the Secondary to Primary, we need to insert new filters before the
> filter-rewriter.
> 
> Add the options insert= and position= to be able to insert filters anywhere 
> in the
> filter list.
> 
> position should be either "head", "tail" or the id of another filter.
> insert should be either "before" or "after" to specify where to insert the new
> filter relative to the one specified with position.
> 

Hi Lukas,

It looks no need to add the "insert = xxx" for this operation.
For example:

We have 3 net-filters, the running order like that:

Fiter1   ---------->   Filter2 ------------> Filter3

If we want to add another filter between filter1 and filter2.
The "Position = head, insert = after" always seam with "position = filter2 id, 
insert = before". It seems the "insert" is a redundant args.
So I think it is enough with the "position", we can make the "insert" always 
equal "after" except the "head".


Thanks
Zhang Chen

> Signed-off-by: Lukas Straub <address@hidden>
> ---
>  include/net/filter.h |  2 ++
>  net/filter.c         | 71 +++++++++++++++++++++++++++++++++++++++++++-
>  qemu-options.hx      | 10 +++----
>  3 files changed, 77 insertions(+), 6 deletions(-)
> 
> diff --git a/include/net/filter.h b/include/net/filter.h index
> 49da666ac0..355c178f75 100644
> --- a/include/net/filter.h
> +++ b/include/net/filter.h
> @@ -62,6 +62,8 @@ struct NetFilterState {
>      NetClientState *netdev;
>      NetFilterDirection direction;
>      bool on;
> +    char *position;
> +    bool insert_before;
>      QTAILQ_ENTRY(NetFilterState) next;
>  };
> 
> diff --git a/net/filter.c b/net/filter.c index 28d1930db7..309fd778df 100644
> --- a/net/filter.c
> +++ b/net/filter.c
> @@ -171,11 +171,47 @@ static void netfilter_set_status(Object *obj, const
> char *str, Error **errp)
>      }
>  }
> 
> +static char *netfilter_get_position(Object *obj, Error **errp) {
> +    NetFilterState *nf = NETFILTER(obj);
> +
> +    return g_strdup(nf->position);
> +}
> +
> +static void netfilter_set_position(Object *obj, const char *str, Error
> +**errp) {
> +    NetFilterState *nf = NETFILTER(obj);
> +
> +    nf->position = g_strdup(str);
> +}
> +
> +static char *netfilter_get_insert(Object *obj, Error **errp) {
> +    NetFilterState *nf = NETFILTER(obj);
> +
> +    return nf->insert_before ? g_strdup("before") : g_strdup("after");
> +}
> +
> +static void netfilter_set_insert(Object *obj, const char *str, Error
> +**errp) {
> +    NetFilterState *nf = NETFILTER(obj);
> +
> +    if (strcmp(str, "before") && strcmp(str, "after")) {
> +        error_setg(errp, "Invalid value for netfilter insert, "
> +                         "should be 'head' or 'tail'");
> +        return;
> +    }
> +
> +    nf->insert_before = !strcmp(str, "before"); }
> +
>  static void netfilter_init(Object *obj)  {
>      NetFilterState *nf = NETFILTER(obj);
> 
>      nf->on = true;
> +    nf->insert_before = false;
> +    nf->position = g_strdup("tail");
> 
>      object_property_add_str(obj, "netdev",
>                              netfilter_get_netdev_id, 
> netfilter_set_netdev_id, @@ -187,11
> +223,18 @@ static void netfilter_init(Object *obj)
>      object_property_add_str(obj, "status",
>                              netfilter_get_status, netfilter_set_status,
>                              NULL);
> +    object_property_add_str(obj, "position",
> +                            netfilter_get_position, netfilter_set_position,
> +                            NULL);
> +    object_property_add_str(obj, "insert",
> +                            netfilter_get_insert, netfilter_set_insert,
> +                            NULL);
>  }
> 
>  static void netfilter_complete(UserCreatable *uc, Error **errp)  {
>      NetFilterState *nf = NETFILTER(uc);
> +    NetFilterState *position = NULL;
>      NetClientState *ncs[MAX_QUEUE_NUM];
>      NetFilterClass *nfc = NETFILTER_GET_CLASS(uc);
>      int queues;
> @@ -219,6 +262,20 @@ static void netfilter_complete(UserCreatable *uc,
> Error **errp)
>          return;
>      }
> 
> +    if (strcmp(nf->position, "head") && strcmp(nf->position, "tail")) {
> +        /* Search for the position to insert before/after */
> +        Object *container;
> +        Object *obj;
> +
> +        container = object_get_objects_root();
> +        obj = object_resolve_path_component(container, nf->position);
> +        if (!obj) {
> +            error_setg(errp, "filter '%s' not found", nf->position);
> +            return;
> +        }
> +        position = NETFILTER(obj);
> +    }
> +
>      nf->netdev = ncs[0];
> 
>      if (nfc->setup) {
> @@ -228,7 +285,18 @@ static void netfilter_complete(UserCreatable *uc,
> Error **errp)
>              return;
>          }
>      }
> -    QTAILQ_INSERT_TAIL(&nf->netdev->filters, nf, next);
> +
> +    if (position) {
> +        if (nf->insert_before) {
> +            QTAILQ_INSERT_BEFORE(position, nf, next);
> +        } else {
> +            QTAILQ_INSERT_AFTER(&nf->netdev->filters, position, nf, next);
> +        }
> +    } else if (!strcmp(nf->position, "head")) {
> +        QTAILQ_INSERT_HEAD(&nf->netdev->filters, nf, next);
> +    } else if (!strcmp(nf->position, "tail")) {
> +        QTAILQ_INSERT_TAIL(&nf->netdev->filters, nf, next);
> +    }
>  }
> 
>  static void netfilter_finalize(Object *obj) @@ -245,6 +313,7 @@ static void
> netfilter_finalize(Object *obj)
>          QTAILQ_REMOVE(&nf->netdev->filters, nf, next);
>      }
>      g_free(nf->netdev_id);
> +    g_free(nf->position);
>  }
> 
>  static void default_handle_event(NetFilterState *nf, int event, Error **errp)
> diff --git a/qemu-options.hx b/qemu-options.hx index 08749a3391..f0a47a0746
> 100644
> --- a/qemu-options.hx
> +++ b/qemu-options.hx
> @@ -4368,7 +4368,7 @@ applications, they can do this through this parameter.
> Its format is  a gnutls priority string as described at
> @url{https://gnutls.org/manual/html_node/Priority-Strings.html}.
> 
> -@item -object filter-
> buffer,id=@var{id},netdev=@var{netdevid},interval=@var{t}[,queue=@var{all|r
> x|tx}][,status=@var{on|off}]
> +@item -object
> +filter-buffer,id=@var{id},netdev=@var{netdevid},interval=@var{t}[,queue
> +=@var{all|rx|tx}][,status=@var{on|off}][,position=@var{head|tail|id}][,
> +insert=@var{after|before}]
> 
>  Interval @var{t} can't be 0, this filter batches the packet delivery: all  
> packets
> arriving in a given interval on netdev @var{netdevid} are delayed @@ -4387,11
> +4387,11 @@ 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=@v
> ar{all|rx|tx}[,vnet_hdr_support]
> +@item -object
> +filter-mirror,id=@var{id},netdev=@var{netdevid},outdev=@var{chardevid},
> +queue=@var{all|rx|tx}[,vnet_hdr_support][,position=@var{head|tail|id}][
> +,insert=@var{after|before}]
> 
>  filter-mirror on netdev @var{netdevid},mirror net packet to
> chardev@var{chardevid}, if it has 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}[,vnet_hdr_support]
> +@item -object
> +filter-redirector,id=@var{id},netdev=@var{netdevid},indev=@var{chardevi
> +d},outdev=@var{chardevid},queue=@var{all|rx|tx}[,vnet_hdr_support][,pos
> +ition=@var{head|tail|id}][,insert=@var{after|before}]
> 
>  filter-redirector on netdev @var{netdevid},redirect filter's net packet to
> chardev  @var{chardevid},and redirect indev's packet to filter.if it has the
> vnet_hdr_support flag, @@ -4400,7 +4400,7 @@ 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},queue=@var{all|rx|tx},[vnet_hdr_
> support]
> +@item -object
> +filter-rewriter,id=@var{id},netdev=@var{netdevid},queue=@var{all|rx|tx}
> +,[vnet_hdr_support][,position=@var{head|tail|id}][,insert=@var{after|be
> +fore}]
> 
>  Filter-rewriter is a part of COLO project.It will rewrite tcp packet to  
> secondary
> from primary to keep secondary tcp connection,and rewrite @@ -4413,7
> +4413,7 @@ colo secondary:
>  -object filter-redirector,id=f2,netdev=hn0,queue=rx,outdev=red1
>  -object filter-rewriter,id=rew0,netdev=hn0,queue=all
> 
> -@item -object filter-
> dump,id=@var{id},netdev=@var{dev}[,file=@var{filename}][,maxlen=@var{len}]
> +@item -object
> +filter-dump,id=@var{id},netdev=@var{dev}[,file=@var{filename}][,maxlen=
> +@var{len}][,position=@var{head|tail|id}][,insert=@var{after|before}]
> 
>  Dump the network traffic on netdev @var{dev} to the file specified by
> @var{filename}. At most @var{len} bytes (64k by default) per packet are 
> stored.
> --
> 2.20.1