Re: [Qemu-devel] [PATCH V2 2/3] net/filter-redirector:Add filter-redirector

[Jason Wang]

On 02/29/2016 08:23 PM, Zhang Chen wrote:
> Filter-redirector is a netfilter plugin.
> It gives qemu the ability to redirect net packet.
> redirector can redirect filter's net packet to outdev.
> and redirect indev's packet to filter.
>
>                              filter
>                                +
>                                |
>                                |
>               redirector       |
>                +-------------------------+
>                |               |         |
>                |               |         |
>                |               |         |
>   indev +----------------+     +---------------->  outdev
>                |         |               |
>                |         |               |
>                |         |               |
>                +-------------------------+
>                          |
>                          |
>                          v
>                       filter
>                          |
>                          |
>                          v
>                       filter------> guest

As we've discussed, the actual destination should depend on "queue"
parameter. E.g if queue = rx, the destination should be netdev not guest.

>
> usage:
>
> -netdev tap,id=hn0
> -chardev socket,id=s0,host=ip_primary,port=X,server,nowait
> -chardev socket,id=s1,host=ip_primary,port=Y,server,nowait
> -filter-redirector,id=r0,netdev=hn0,queue=tx/rx/all,indev=s0,outdev=s1
>
> Signed-off-by: Zhang Chen <address@hidden>
> Signed-off-by: Wen Congyang <address@hidden>
> ---
>  net/Makefile.objs       |   1 +
>  net/filter-redirector.c | 216 
> ++++++++++++++++++++++++++++++++++++++++++++++++
>  qemu-options.hx         |   8 ++
>  vl.c                    |   3 +-
>  4 files changed, 227 insertions(+), 1 deletion(-)
>  create mode 100644 net/filter-redirector.c
>
> diff --git a/net/Makefile.objs b/net/Makefile.objs
> index b7c22fd..8af9932 100644
> --- a/net/Makefile.objs
> +++ b/net/Makefile.objs
> @@ -16,3 +16,4 @@ common-obj-$(CONFIG_NETMAP) += netmap.o
>  common-obj-y += filter.o
>  common-obj-y += filter-buffer.o
>  common-obj-y += filter-mirror.o
> +common-obj-y += filter-redirector.o
> diff --git a/net/filter-redirector.c b/net/filter-redirector.c
> new file mode 100644
> index 0000000..d0eb76d
> --- /dev/null
> +++ b/net/filter-redirector.c
> @@ -0,0 +1,216 @@
> +/*
> + * Copyright (c) 2016 HUAWEI TECHNOLOGIES CO., LTD.
> + * Copyright (c) 2016 FUJITSU LIMITED
> + * Copyright (c) 2016 Intel Corporation
> + *
> + * Author: Zhang Chen <address@hidden>
> + *
> + * 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-traffic.h"
> +
> +#define FILTER_REDIRECTOR(obj) \
> +    OBJECT_CHECK(TrafficState, (obj), TYPE_FILTER_REDIRECTOR)
> +
> +#define TYPE_FILTER_REDIRECTOR "filter-redirector"
> +#define REDIRECT_HEADER_LEN sizeof(uint32_t)
> +
> +static int filter_redirector_send(NetFilterState *nf,
> +                                   const struct iovec *iov,
> +                                   int iovcnt)
> +{
> +    return filter_traffic_send(nf, iov, iovcnt);
> +}
> +
> +static ssize_t filter_redirector_receive_iov(NetFilterState *nf,
> +                                         NetClientState *sender,
> +                                         unsigned flags,
> +                                         const struct iovec *iov,
> +                                         int iovcnt,
> +                                         NetPacketSent *sent_cb)
> +{
> +    TrafficState *s = FILTER_REDIRECTOR(nf);
> +    ssize_t ret = 0;
> +
> +    if (s->chr_out) {
> +        ret = filter_redirector_send(nf, iov, iovcnt);
> +        if (ret < 0) {
> +            error_report("filter_redirector_send failed");
> +        }
> +        return iov_size(iov, iovcnt);
> +    } else {
> +        return 0;
> +    }
> +}
> +
> +static void filter_redirector_cleanup(NetFilterState *nf)
> +{
> +    TrafficState *s = FILTER_REDIRECTOR(nf);
> +
> +    if (s->chr_in) {
> +        qemu_chr_fe_release(s->chr_in);
> +    }
> +    if (s->chr_out) {
> +        qemu_chr_fe_release(s->chr_out);
> +    }
> +}
> +
> +static int redirector_chr_can_read(void *opaque)
> +{
> +    return REDIRECT_HEADER_LEN;
> +}
> +
> +static void redirector_chr_read(void *opaque, const uint8_t *buf, int size)
> +{
> +    NetFilterState *nf = opaque;
> +    TrafficState *s = FILTER_REDIRECTOR(nf);
> +    uint32_t len;
> +    int ret = 0;
> +    uint8_t *recv_buf;
> +    int offset = size;
> +
> +    while (offset < REDIRECT_HEADER_LEN) {
> +        ret = s->chr_in->chr_sync_read(s->chr_in, (uint8_t *)buf + offset,
> +                REDIRECT_HEADER_LEN - offset);
> +        if (ret == -1 && errno == EAGAIN) {
> +            g_usleep(100);
> +        }
> +        offset += ret;

Why not use qemu_chr_fe_read_all() here?

And what's better, instead of busy waiting/reading. You can save the
partial packet in a temporary buffer, and do not forward it after it has
been completely received.


> +    }
> +
> +    memcpy(&len, buf, sizeof(len));
> +    len = ntohl(len);
> +
> +    if (len > 0 && len < NET_BUFSIZE) {
> +        recv_buf = g_malloc(len);
> +        ret = qemu_chr_fe_read_all(s->chr_in, recv_buf, len);
> +        if (ret != len) {
> +            error_report("filter-redirector recv buf failed");
> +            g_free(recv_buf);
> +            return;
> +        }
> +
> +        ret = qemu_net_queue_send(s->incoming_queue, nf->netdev,
> +                            0, (const uint8_t *)recv_buf, len, NULL);

As I replied in last version. Sender should be chose depending on
'queues'. When 'queue=rx' sender should be be netdev's peer.