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

[Zhang Chen <zhangchen.fnst@cn.fujitsu.com>]

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.


>
> - 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 ?

> 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.

>> +    if (ret < 0) {
> This check is not sufficient, for some reason, only part of the packets
> maybe sent by the socket. Need to handle this properly, otherwise it may
> confuse receiver.

I will fix it in next version.

>> +        g_free(buf);
>> +        return ret;
>> +    }
>> +
>> +    ret = qemu_chr_fe_write(s->chr_out, (uint8_t *)buf, size);
>> +    g_free(buf);
>> +    return ret;
> Ditto.

I will fix it in next version.

>> +}
>> +
>> +static ssize_t traffic_mirror_receive_iov(NetFilterState *nf,
>> +                                         NetClientState *sender,
>> +                                         unsigned flags,
>> +                                         const struct iovec *iov,
>> +                                         int iovcnt,
>> +                                         NetPacketSent *sent_cb)
>> +{
>> +    /*
>> +     * We copy and mirror packet to outdev,
>> +     * then put back the packet.
>> +     */
> The code could explain itself, so the comment is unnecessary.

OK,I will remove it.

Thanks
zhangchen

>> +    ssize_t ret = 0;
>> +
>> +    ret = traffic_mirror_send(nf, iov, iovcnt);
>> +    if (ret < 0) {
>> +        error_report("traffic_mirror_send failed");
> Monitor could be flooded by this.
>
>> +    }
>> +
>> +    return 0;
>> +}
>> +
> Other looks good.
>
>
>
> .
>

-- 
Thanks
zhangchen