Re: [dpdk-dev] [PATCH v3 01/11] ethdev: add extensions attributes to IPv6 item

[Ajit Khaparde <ajit.khaparde@broadcom.com>]

On Mon, Oct 5, 2020 at 1:37 AM Dekel Peled <dekelp@nvidia.com> wrote:
>
> Using the current implementation of DPDK, an application cannot match on
> IPv6 packets, based on the existing extension headers, in a simple way.
>
> Field 'Next Header' in IPv6 header indicates type of the first extension
> header only. Following extension headers can't be identified by
> inspecting the IPv6 header.
> As a result, the existence or absence of specific extension headers
> can't be used for packet matching.
>
> For example, fragmented IPv6 packets contain a dedicated extension header
> (which is implemented in a later patch of this series).
> Non-fragmented packets don't contain the fragment extension header.
> For an application to match on non-fragmented IPv6 packets, the current
> implementation doesn't provide a suitable solution.
> Matching on the Next Header field is not sufficient, since additional
> extension headers might be present in the same packet.
> To match on fragmented IPv6 packets, the same difficulty exists.
>
> This patch implements the update as detailed in RFC [1].
> A set of additional values will be added to IPv6 header struct.
> These values will indicate the existence of every defined extension
> header type, providing simple means for identification of existing
> extensions in the packet header.
> Continuing the above example, fragmented packets can be identified using
> the specific value indicating existence of fragment extension header.
>
> [1] https://mails.dpdk.org/archives/dev/2020-August/177257.html
>
> Signed-off-by: Dekel Peled <dekelp@nvidia.com>
> Acked-by: Ori Kam <orika@nvidia.com>
> ---
>  doc/guides/prog_guide/rte_flow.rst | 16 +++++++++++++---
>  lib/librte_ethdev/rte_flow.h       | 25 +++++++++++++++++++++++--
>  2 files changed, 36 insertions(+), 5 deletions(-)
>
> diff --git a/doc/guides/prog_guide/rte_flow.rst b/doc/guides/prog_guide/rte_flow.rst
> index 119b128..0b476da 100644
> --- a/doc/guides/prog_guide/rte_flow.rst
> +++ b/doc/guides/prog_guide/rte_flow.rst
> @@ -946,11 +946,21 @@ Item: ``IPV6``
>
>  Matches an IPv6 header.
>
> -Note: IPv6 options are handled by dedicated pattern items, see `Item:
> -IPV6_EXT`_.
> +Dedicated flags indicate existence of specific extension headers.
> +Every type of extension header can use a dedicated pattern item, or
> +the generic `Item: IPV6_EXT`_.

Can you add how the PMD should interpret if these flags are not set
by the application.
There is a mention of some of that in the testpmd commit log.
I think it is good to spell it out here.

>
>  - ``hdr``: IPv6 header definition (``rte_ip.h``).
> -- Default ``mask`` matches source and destination addresses only.
> +- ``hop_ext_exist``: Hop-by-Hop Options extension header exists.
> +- ``rout_ext_exist``: Routing extension header exists.
> +- ``frag_ext_exist``: Fragment extension header exists.
> +- ``auth_ext_exist``: Authentication extension header exists.
> +- ``esp_ext_exist``: Encapsulation Security Payload extension header exists.
> +- ``dest_ext_exist``: Destination Options extension header exists.
> +- ``mobil_ext_exist``: Mobility extension header exists.
> +- ``hip_ext_exist``: Host Identity Protocol extension header exists.
> +- ``shim6_ext_exist``: Shim6 Protocol extension header exists.
> +- Default ``mask`` matches ``hdr`` source and destination addresses only.
>
>  Item: ``ICMP``
>  ^^^^^^^^^^^^^^
> diff --git a/lib/librte_ethdev/rte_flow.h b/lib/librte_ethdev/rte_flow.h
> index da8bfa5..5b5bed2 100644
> --- a/lib/librte_ethdev/rte_flow.h
> +++ b/lib/librte_ethdev/rte_flow.h
> @@ -792,11 +792,32 @@ struct rte_flow_item_ipv4 {
>   *
>   * Matches an IPv6 header.
>   *
> - * Note: IPv6 options are handled by dedicated pattern items, see
> - * RTE_FLOW_ITEM_TYPE_IPV6_EXT.
> + * Dedicated flags indicate existence of specific extension headers.
> + * Every type of extension header can use a dedicated pattern item, or
> + * the generic item RTE_FLOW_ITEM_TYPE_IPV6_EXT.
>   */
>  struct rte_flow_item_ipv6 {
>         struct rte_ipv6_hdr hdr; /**< IPv6 header definition. */
> +       uint32_t hop_ext_exist:1;
> +       /**< Hop-by-Hop Options extension header exists. */
> +       uint32_t rout_ext_exist:1;
> +       /**< Routing extension header exists. */
> +       uint32_t frag_ext_exist:1;
> +       /**< Fragment extension header exists. */
> +       uint32_t auth_ext_exist:1;
> +       /**< Authentication extension header exists. */
> +       uint32_t esp_ext_exist:1;
> +       /**< Encapsulation Security Payload extension header exists. */
> +       uint32_t dest_ext_exist:1;
> +       /**< Destination Options extension header exists. */
> +       uint32_t mobil_ext_exist:1;
> +       /**< Mobility extension header exists. */
> +       uint32_t hip_ext_exist:1;
> +       /**< Host Identity Protocol extension header exists. */
> +       uint32_t shim6_ext_exist:1;
> +       /**< Shim6 Protocol extension header exists. */
> +       uint32_t reserved:23;
> +       /**< Reserved for future extension headers, must be zero. */
>  };
>
>  /** Default mask for RTE_FLOW_ITEM_TYPE_IPV6. */
> --
> 1.8.3.1
>