[ovs-dev] [PATCH] conntrack: Fix tcp payload length in case multi-segments.

[Darrell Ball]

Thanks for the patch

Would you mind describing the use case that this patch is aiming to support
?

On Fri, Nov 8, 2019 at 1:23 AM Zhike Wang <wangzk320 at 163.com> wrote:

> Signed-off-by: Zhike Wang <wangzk320 at 163.com>
> ---
>  lib/conntrack-private.h | 16 ++++++++++------
>  1 file changed, 10 insertions(+), 6 deletions(-)
>
> diff --git a/lib/conntrack-private.h b/lib/conntrack-private.h
> index 590f139..1d21f6e 100644
> --- a/lib/conntrack-private.h
> +++ b/lib/conntrack-private.h
> @@ -233,13 +233,17 @@ conn_update_expiration(struct conntrack *ct, struct
> conn *conn,
>  static inline uint32_t
>  tcp_payload_length(struct dp_packet *pkt)
>  {
> -    const char *tcp_payload = dp_packet_get_tcp_payload(pkt);
> -    if (tcp_payload) {
> -        return ((char *) dp_packet_tail(pkt) - dp_packet_l2_pad_size(pkt)
> -                - tcp_payload);
> -    } else {
> -        return 0;
> +    size_t l4_size = dp_packet_l4_size(pkt);
> +
> +    if (OVS_LIKELY(l4_size >= TCP_HEADER_LEN)) {
> +        struct tcp_header *tcp = dp_packet_l4(pkt);
> +        int tcp_len = TCP_OFFSET(tcp->tcp_ctl) * 4;
> +
> +        if (OVS_LIKELY(tcp_len >= TCP_HEADER_LEN && tcp_len <= l4_size)) {
> +            return (l4_size - tcp_len);
> +        }
>

Maybe I missed something, but it looks like the same calculation is arrived
at.


>      }
> +    return 0;
>  }
>
>  #endif /* conntrack-private.h */
> --
> 1.8.3.1
>
>
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