Re: [Qemu-devel] [PATCH 0/9] For QEMU 2.5: Add a net filter and a netbuffer plugin based on the filter

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

On 2015/7/24 18:55, Yang Hongyang wrote:
> This patch add a net filter between network backend and NIC devices.
> All packets will pass by this filter.
> Also implement a netbuffer plugin for example, the netbuffer plugin
> could be used by VM FT solutions like Macrocheckpointing,
> to buffer/release packets.
> Based on this, dump plugin could be easily implemented.
>
> I've done some simple tests on this series,
> backend, tap,user
> NIC, e1000,virtio-net
>
> There's still some missing functions to be done, I've posted this
> early in order to gain more comments, thank you!
>
> TODO:
>    multiqueue support.
>
>                  +--------------+       +-------------+
>    +----------+  |    filter    |       |frontend(NIC)|
>    |      peer+-->              |       |             |
>    | network  <--+backend       <-------+ peer        |
>    | backend  |  |         peer +------->             |
>    +----------+  +--------------+       +-------------+
>
> Usage:
>    -netdev tap,id=bn0  # you can use whatever backend as needed
>    -netdev filter,id=f0,backend=bn0
>    -netdev filter-<plugin>,id=p0,filter=f0
>    -device e1000,netdev=f0

Have you considered Daniel's suggestion ? Using the bellow style:
   -netfilter id=f0,plugin=dump
   -netdev tap,id=bn0,filter=f0
   -device e1000,netdev=bn0

Considering the filter as a new 'netdev' seems to be unreasonable,
Whenever we add a new plugin, we have to add a new member to
'NetClientOptions', there will be lots of 'filter' objects in NetClientOptions
area. Besides when we want to describe a net device with several filter plugin for VM,
it will become like:
    -netdev tap,id=bn0
    -netdev filter,id=f0,backend=bn0
    -netdev filter-<plugin-0>,id=p0,filter=f0
    -netdev filter-<plugin-1>,id=p1,filter=f1
    ... ...
    -device e1000,netdev=f0
Which is a little verbose for 'netdev' option.
We'd better come to an agreement on the command line style for net filter :)

Cc: Daniel P. Berrange <berrange@redhat.com>

Thanks,
zhanghailiang

> NOTE:
>    You can attach multiple plugins to the filter, dynamically add/remove
> filter and filter-<plugin>.
>
> The netbuffer plugin:
> Usage:
>    -netdev tap,id=bn0  # you can use whatever backend as needed
>    -netdev filter,id=f0,backend=bn0
>    -netdev filter-buffer,id=p0,filter=f0
>    -device e1000,netdev=f0
>
> Will supply a public API to release the buffer. But there's no
> callers currently.
> To test this feature, it's quite simple, just use
> netdev_add filter-buffer,id=p0,filter=f0
> to buffer packets,
> netdev_del p0
> will release packets.
>
> You can also implement whatever plugin you needed based on this filter.
>
> Yang Hongyang (9):
>    netdev: Add a net filter
>    virtio-net: add filter support
>    filter: remove plugins when remove filter
>    filter: remove filter before remove network backend
>    filter: add netbuffer plugin
>    introduce qemu_find_net_clients_by_model
>    net/queue: export qemu_net_queue_append
>    move out net queue structs define
>    add a public api to release buffer
>
>   hw/net/virtio-net.c  |  17 ++-
>   include/net/filter.h |  21 ++++
>   include/net/net.h    |   5 +
>   include/net/queue.h  |  26 ++++
>   net/Makefile.objs    |   2 +
>   net/clients.h        |   6 +
>   net/filter-buffer.c  | 185 ++++++++++++++++++++++++++++
>   net/filter.c         | 331 +++++++++++++++++++++++++++++++++++++++++++++++++++
>   net/net.c            |  51 +++++++-
>   net/queue.c          |  31 +----
>   qapi-schema.json     |  40 ++++++-
>   11 files changed, 679 insertions(+), 36 deletions(-)
>   create mode 100644 include/net/filter.h
>   create mode 100644 net/filter-buffer.c
>   create mode 100644 net/filter.c
>