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

[Hailiang Zhang <zhang.zhanghailiang@huawei.com>]

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 <zhang.zhanghailiang@huawei.com>
>> ---
>> 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
>