Re: [Qemu-devel] [PATCH V2] net/traffic-mirror:Add traffic-mirror

[Jason Wang <jasowang@redhat.com>]

On 01/28/2016 03:44 PM, Zhang Chen wrote:
>
>
> On 01/28/2016 01:44 PM, Jason Wang wrote:
>>
>> On 01/27/2016 10:40 AM, Zhang Chen wrote:
>>> From: ZhangChen <zhangchen.fnst@cn.fujitsu.com>
>>>
>>> Traffic-mirror is a netfilter plugin.
>>> It gives qemu the ability to copy and mirror guest's
>>> net packet. we output packet to chardev.
>>>
>>> usage:
>>>
>>> -netdev tap,id=hn0
>>> -chardev socket,id=mirror0,host=ip_primary,port=X,server,nowait
>>> -traffic-mirror,id=m0,netdev=hn0,queue=tx/rx/all,outdev=mirror0
>>>
>>> Signed-off-by: ZhangChen <zhangchen.fnst@cn.fujitsu.com>
>>> Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
>>> Reviewed-by: Yang Hongyang <hongyang.yang@easystack.cn>
>> Thanks for the patch. Several questions:
>>
>> - I'm curious about how the patch was tested? Simple setup e.g:
>>
>> -netdev tap,id=hn0 -device virtio-net-pci,netdev=hn0 -chardev
>> socket,id=c0,host=localhost,port=4444,server,nowait -object
>> traffic-mirror,netdev=hn0,outdev=c0,id=f0 -netdev
>> socket,id=s0,connect=127.0.0.1:4444 -device e1000,netdev=s0
>>
>> does not works for me.
>
> I test it in this way.
> primary:
> -netdev tap,id=hn0 -device e1000,netdev=hn0 -chardev
> socket,id=mirror0,host=3.3.3.3,port=9003,server,nowait
>  -object traffic-mirror,id=f0,netdev=hn0,queue=tx,outdev=mirror0
>
> secondary:
> -netdev tap,id=hn0 -device e1000,netdev=hn0 -chardev
> socket,id=mirror0,host=3.3.3.3,port=9003 -object
> traffic-reader,id=f1,netdev=hn0,queue=rx,indev=mirror0
>
> I write a traffic-reader demo to read chardev socket and print it in
> monitor.

Ok, but maybe you can try socket backend. I think the protocol should be
at least compatible with it.

>
>
>>
>> - Is a reliable mirroring (e.g no packet drops during mirroring) is
>> needed for COLO? If yes, this patch seems could not guarantee this.
>
> I will fix it in V3
>
>> - Please consider to write a unit test for this patch.
>
> write a unit test like tests/test-netfilter.c ?

Even more for its basic function to work. E.g, start qemu with:

-netdev socket,id=s0,listen=localhost:X -chardev
socket,id=c0,host=localhost,pory=Y,server,nowait -object
filter-mirror,netdev=hn0,outdev=c0

Then you can inject packet from the socket connected to s0 and see if
you can read it from socket that connected from c0 (or your traffic reader).

>
>> And see comments below.
>>
>> Thanks
>>
>>
>>> ---
>>>   net/Makefile.objs    |   1 +
>>>   net/traffic-mirror.c | 173
>>> +++++++++++++++++++++++++++++++++++++++++++++++++++
>>>   qemu-options.hx      |   5 ++
>>>   vl.c                 |   3 +-
>>>   4 files changed, 181 insertions(+), 1 deletion(-)
>>>   create mode 100644 net/traffic-mirror.c
>>>
>>> diff --git a/net/Makefile.objs b/net/Makefile.objs
>>> index 5fa2f97..de06ebe 100644
>>> --- a/net/Makefile.objs
>>> +++ b/net/Makefile.objs
>>> @@ -15,3 +15,4 @@ common-obj-$(CONFIG_VDE) += vde.o
>>>   common-obj-$(CONFIG_NETMAP) += netmap.o
>>>   common-obj-y += filter.o
>>>   common-obj-y += filter-buffer.o
>>> +common-obj-y += traffic-mirror.o
>> Let's s/traffic-mirror/filter-mirror/g to be consistent with other
>> filters.
>>
>
> OK~ I will fix it in V3
>
>>> diff --git a/net/traffic-mirror.c b/net/traffic-mirror.c
>>> new file mode 100644
>>> index 0000000..bed915c
>>> --- /dev/null
>>> +++ b/net/traffic-mirror.c
>>> @@ -0,0 +1,173 @@
>>> +/*
>>> + * Copyright (c) 2016 HUAWEI TECHNOLOGIES CO., LTD.
>>> + * Copyright (c) 2016 FUJITSU LIMITED
>>> + * Copyright (c) 2016 Intel Corporation
>>> + *
>>> + * Author: Zhang Chen <zhangchen.fnst@cn.fujitsu.com>
>>> + *
>>> + * This work is licensed under the terms of the GNU GPL, version 2 or
>>> + * later.  See the COPYING file in the top-level directory.
>>> + */
>>> +
>>> +#include "net/filter.h"
>>> +#include "net/net.h"
>>> +#include "qemu-common.h"
>>> +#include "qapi/qmp/qerror.h"
>>> +#include "qapi-visit.h"
>>> +#include "qom/object.h"
>>> +#include "qemu/main-loop.h"
>>> +#include "qemu/error-report.h"
>>> +#include "trace.h"
>>> +#include "sysemu/char.h"
>>> +#include "qemu/iov.h"
>>> +
>>> +#define FILTER_TRAFFIC_MIRROR(obj) \
>>> +    OBJECT_CHECK(MirrorState, (obj), TYPE_FILTER_TRAFFIC_MIRROR)
>>> +
>>> +#define TYPE_FILTER_TRAFFIC_MIRROR "traffic-mirror"
>>> +
>>> +typedef struct MirrorState {
>>> +    NetFilterState parent_obj;
>>> +    char *outdev;
>>> +    CharDriverState *chr_out;
>>> +
>>> +} MirrorState;
>>> +
>>> +static ssize_t traffic_mirror_send(NetFilterState *nf,
>>> +                                   const struct iovec *iov,
>>> +                                   int iovcnt)
>>> +{
>>> +    MirrorState *s = FILTER_TRAFFIC_MIRROR(nf);
>>> +    ssize_t ret = 0;
>>> +    ssize_t size = 0;
>>> +    char *buf;
>>> +
>>> +    size = iov_size(iov, iovcnt);
>>> +    if (!size) {
>>> +        return 0;
>>> +    }
>>> +
>>> +    buf = g_malloc0(size);
>>> +    iov_to_buf(iov, iovcnt, 0, buf, size);
>>> +    ret = qemu_chr_fe_write(s->chr_out, (uint8_t *)&size,
>>> sizeof(size));
>> htonl(size)?
>
> We do not need this.
>

Why? Did you test your mirroring on the wire?

Thanks