Re: [Qemu-devel] [PATCH RFC v2 3/5] net/filter: Introduce a helper to add a filter to the netdev

[Hailiang Zhang]

On 2016/2/1 18:43, Daniel P. Berrange wrote:
> On Wed, Jan 27, 2016 at 04:29:38PM +0800, zhanghailiang wrote:
> > We add a new helper function netdev_add_filter(), this function
> > can help adding a filter object to a netdev.
> > Besides, we add a is_default member for struct NetFilterState
> > to indicate whether the filter is default or not.
> >
> > Signed-off-by: zhanghailiang <address@hidden>
> > ---
> > v2:
> >   -Re-implement netdev_add_filter() by re-using object_create()
> >    (Jason's suggestion)
> > ---
> >   include/net/filter.h |  7 +++++
> >   net/filter.c         | 80 ++++++++++++++++++++++++++++++++++++++++++++++++++++
> >   2 files changed, 87 insertions(+)
>
> > +void netdev_add_filter(const char *netdev_id,
> > +                       const char *filter_type,
> > +                       const char *id,
> > +                       bool is_default,
> > +                       Error **errp)
> > +{
> > +    NetClientState *nc = qemu_find_netdev(netdev_id);
> > +    char *optarg;
> > +    QemuOpts *opts = NULL;
> > +    Error *err = NULL;
> > +
> > +    /* FIXME: Not support multiple queues */
> > +    if (!nc || nc->queue_index > 1) {
> > +        return;
> > +    }
> > +    /* Not support vhost-net */
> > +    if (get_vhost_net(nc)) {
> > +        return;
> > +    }
> > +
> > +    optarg = g_strdup_printf("qom-type=%s,id=%s,netdev=%s,status=%s",
> > +            filter_type, id, netdev_id, is_default ? "disable" : "enable");
> > +    opts = qemu_opts_parse_noisily(&qemu_filter_opts,
> > +                                   optarg, false);
>
> Formatting a string and then immediately parsing it again is totally
> crazy, not least because you're not taking care to do escaping of
> special characters like ',' in the string parameters.

Got it.

> > +    if (!opts) {
> > +        error_report("Failed to parse param '%s'", optarg);
> > +        exit(1);
> > +    }
> > +    g_free(optarg);
> > +    if (object_create(NULL, opts, &err) < 0) {
> > +        error_report("Failed to create object");
> > +        goto out_clean;
> > +    }
>
> Don't use object_create() - use object_new_with_props() which avoids
> the need to format + parse the string above. ie do
>
>    object_new_with_props(filter_type,
>                          object_get_objects_root(),
>                         id,
>                         &err,
>                         "netdev", netdev_id,
>                         "status", is_default ? "disable" : "enable",
>                         NULL);

Ha, that's really a good idea, i will fix it like that
in next version. Thank you very much.

Hailiang

> Regards,
> Daniel