Re: [Qemu-devel] [PATCH V11 8/9] filter-rewriter: track connection and parse packet

[Jason Wang <jasowang@redhat.com>]

On 2016年07月28日 18:12, Zhang Chen wrote:
> We use colo-base.h to track connection and parse packet
>
> Signed-off-by: Zhang Chen <zhangchen.fnst@cn.fujitsu.com>
> Signed-off-by: Li Zhijian <lizhijian@cn.fujitsu.com>
> Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
> ---
>   net/colo-base.c       | 14 ++++++++++++++
>   net/colo-base.h       |  1 +
>   net/filter-rewriter.c | 50 ++++++++++++++++++++++++++++++++++++++++++++++++++
>   3 files changed, 65 insertions(+)
>
> diff --git a/net/colo-base.c b/net/colo-base.c
> index eb1b631..20797b5 100644
> --- a/net/colo-base.c
> +++ b/net/colo-base.c
> @@ -103,6 +103,20 @@ void fill_connection_key(Packet *pkt, ConnectionKey *key)
>       }
>   }
>   
> +void reverse_connection_key(ConnectionKey *key)
> +{
> +    struct in_addr tmp_ip;
> +    uint16_t tmp_port;
> +
> +    tmp_ip = key->src;
> +    key->src = key->dst;
> +    key->dst = tmp_ip;
> +
> +    tmp_port = key->src_port;
> +    key->src_port = key->dst_port;
> +    key->dst_port = tmp_port;
> +}
> +
>   Connection *connection_new(ConnectionKey *key)
>   {
>       Connection *conn = g_slice_new(Connection);
> diff --git a/net/colo-base.h b/net/colo-base.h
> index 860a148..8d402a3 100644
> --- a/net/colo-base.h
> +++ b/net/colo-base.h
> @@ -56,6 +56,7 @@ uint32_t connection_key_hash(const void *opaque);
>   int connection_key_equal(const void *opaque1, const void *opaque2);
>   int parse_packet_early(Packet *pkt);
>   void fill_connection_key(Packet *pkt, ConnectionKey *key);
> +void reverse_connection_key(ConnectionKey *key);
>   Connection *connection_new(ConnectionKey *key);
>   void connection_destroy(void *opaque);
>   Connection *connection_get(GHashTable *connection_track_table,
> diff --git a/net/filter-rewriter.c b/net/filter-rewriter.c
> index 3a39f52..6350080 100644
> --- a/net/filter-rewriter.c
> +++ b/net/filter-rewriter.c
> @@ -51,6 +51,20 @@ static void filter_rewriter_flush(NetFilterState *nf)
>       }
>   }
>   
> +/*
> + * Return 1 on success, if return 0 means the pkt
> + * is not TCP packet
> + */
> +static int is_tcp_packet(Packet *pkt)
> +{
> +    if (!parse_packet_early(pkt) &&
> +        pkt->ip->ip_p == IPPROTO_TCP) {
> +        return 1;
> +    } else {
> +        return 0;
> +    }
> +}
> +
>   static ssize_t colo_rewriter_receive_iov(NetFilterState *nf,
>                                            NetClientState *sender,
>                                            unsigned flags,
> @@ -58,11 +72,47 @@ static ssize_t colo_rewriter_receive_iov(NetFilterState *nf,
>                                            int iovcnt,
>                                            NetPacketSent *sent_cb)
>   {
> +    RewriterState *s = FILTER_COLO_REWRITER(nf);
> +    Connection *conn;
> +    ConnectionKey key = {{ 0 } };
> +    Packet *pkt;
> +    ssize_t size = iov_size(iov, iovcnt);
> +    char *buf = g_malloc0(size);
> +
> +    iov_to_buf(iov, iovcnt, 0, buf, size);
> +    pkt = packet_new(buf, size);
> +
>       /*
>        * if we get tcp packet
>        * we will rewrite it to make secondary guest's
>        * connection established successfully
>        */
> +    if (is_tcp_packet(pkt)) {
> +
> +        fill_connection_key(pkt, &key);
> +
> +        if (sender == nf->netdev) {
> +            /*
> +             * We need make tcp TX and RX packet
> +             * into one connection.
> +             */
> +            reverse_connection_key(&key);

Why not simply do the comparing and swap in fill_connection_key()?

> +        }
> +        conn = connection_get(s->connection_track_table,
> +                              &key,
> +                              &s->hashtable_size);
> +
> +        if (sender == nf->netdev) {
> +            /* NET_FILTER_DIRECTION_TX */
> +            /* handle_primary_tcp_pkt */
> +        } else {
> +            /* NET_FILTER_DIRECTION_RX */
> +            /* handle_secondary_tcp_pkt */
> +        }
> +    }
> +
> +    packet_destroy(pkt, NULL);
> +    pkt = NULL;
>       return 0;
>   }
>