Re: [dpdk-dev] [PATCH 1/3] ethdev: add actions to modify TCP header fields

[Adrien Mazarguil <adrien.mazarguil@6wind.com>]

Hi Derek,

It's been a while since I last reviewed something, sorry it took so long.
Some comments below.

On Thu, Mar 21, 2019 at 04:18:35PM +0200, Dekel Peled wrote:
> Add actions:
> - INC_TCP_SEQ - Increase sequence number in the outermost TCP header.
> - DEC_TCP_SEQ - Decrease sequence number in the outermost TCP header.
> - INC_TCP_ACK - Increase acknowledgment number in the outermost TCP
> 		header.
> - DEC_TCP_ACK - Decrease acknowledgment number in the outermost TCP
> 		header.

Out of curiosity, are these upcoming/existing OpenFlow actions? If so you
should consider prefixing them with "OF_", otherwise leave them as is.

> Original work by Xiaoyu Min.
> 
> Signed-off-by: Dekel Peled <dekelp@mellanox.com>
> ---
>  doc/guides/prog_guide/rte_flow.rst | 72 ++++++++++++++++++++++++++++++++++++++
>  lib/librte_ethdev/rte_flow.c       |  8 +++++
>  lib/librte_ethdev/rte_flow.h       | 60 +++++++++++++++++++++++++++++++
>  3 files changed, 140 insertions(+)
> 
> diff --git a/doc/guides/prog_guide/rte_flow.rst b/doc/guides/prog_guide/rte_flow.rst
> index 0203f4f..bdb817a 100644
> --- a/doc/guides/prog_guide/rte_flow.rst
> +++ b/doc/guides/prog_guide/rte_flow.rst
> @@ -2345,6 +2345,78 @@ Otherwise, RTE_FLOW_ERROR_TYPE_ACTION error will be returned.
>     | ``mac_addr`` | MAC address   |
>     +--------------+---------------+
>  
> +Action: ``INC_TCP_SEQ``
> +^^^^^^^^^^^^^^^^^^^^^^^
> +
> +Increase sequence number in the outermost TCP header.
> +
> +It must be used with a valid RTE_FLOW_ITEM_TYPE_TCP flow pattern item.
> +Otherwise, RTE_FLOW_ERROR_TYPE_ACTION error will be returned.

I know this is already present for various SET* actions, but please do not
tie actions to the presence of specific pattern items at the API level. You
can describe that the lack of a TCP header in matched *traffic* results in
unspecified behavior though.

Then PMD documentation can describe that the lack of a TCP pattern item with
this action results in RTE_FLOW_ERROR_TYPE_ACTION as a PMD-specific
constraint.

> +
> +.. _table_rte_flow_action_inc_tcp_seq:
> +
> +.. table:: INC_TCP_SEQ
> +
> +   +-----------+--------------------------------------------+
> +   | Field     | Value                                      |
> +   +===========+============================================+
> +   | ``value`` | Value to increase TCP sequence number by   |
> +   +-----------+--------------------------------------------+

Nit: unnecessary empty space after "by".

> +
> +Action: ``DEC_TCP_SEQ``
> +^^^^^^^^^^^^^^^^^^^^^^^
> +
> +Decrease sequence number in the outermost TCP header.
> +
> +It must be used with a valid RTE_FLOW_ITEM_TYPE_TCP flow pattern item.
> +Otherwise, RTE_FLOW_ERROR_TYPE_ACTION error will be returned.

Same comment as above.

> +
> +.. _table_rte_flow_action_dec_tcp_seq:
> +
> +.. table:: DEC_TCP_SEQ
> +
> +   +-----------+--------------------------------------------+
> +   | Field     | Value                                      |
> +   +===========+============================================+
> +   | ``value`` | Value to decrease TCP sequence number by   |
> +   +-----------+--------------------------------------------+
> +
> +Action: ``INC_TCP_ACK``
> +^^^^^^^^^^^^^^^^^^^^^^^
> +
> +Increase acknowledgment number in the outermost TCP header.
> +
> +It must be used with a valid RTE_FLOW_ITEM_TYPE_TCP flow pattern item.
> +Otherwise, RTE_FLOW_ERROR_TYPE_ACTION error will be returned.

Ditto.

> +
> +.. _table_rte_flow_action_inc_tcp_ack:
> +
> +.. table:: INC_TCP_ACK
> +
> +   +-----------+--------------------------------------------------+
> +   | Field     | Value                                            |
> +   +===========+==================================================+
> +   | ``value`` | Value to increase TCP acknowledgment number by   |
> +   +-----------+--------------------------------------------------+
> +
> +Action: ``DEC_TCP_ACK``
> +^^^^^^^^^^^^^^^^^^^^^^^
> +
> +Decrease acknowledgment number in the outermost TCP header.
> +
> +It must be used with a valid RTE_FLOW_ITEM_TYPE_TCP flow pattern item.
> +Otherwise, RTE_FLOW_ERROR_TYPE_ACTION error will be returned.

Ditto.

> +
> +.. _table_rte_flow_action_dec_tcp_ack:
> +
> +.. table:: DEC_TCP_ACK
> +
> +   +-----------+--------------------------------------------------+
> +   | Field     | Value                                            |
> +   +===========+==================================================+
> +   | ``value`` | Value to decrease TCP acknowledgment number by   |
> +   +-----------+--------------------------------------------------+
> +
>  Negative types
>  ~~~~~~~~~~~~~~
>  
> diff --git a/lib/librte_ethdev/rte_flow.c b/lib/librte_ethdev/rte_flow.c
> index 3277be1..589d0b9 100644
> --- a/lib/librte_ethdev/rte_flow.c
> +++ b/lib/librte_ethdev/rte_flow.c
> @@ -143,6 +143,14 @@ struct rte_flow_desc_data {
>  	MK_FLOW_ACTION(SET_TTL, sizeof(struct rte_flow_action_set_ttl)),
>  	MK_FLOW_ACTION(SET_MAC_SRC, sizeof(struct rte_flow_action_set_mac)),
>  	MK_FLOW_ACTION(SET_MAC_DST, sizeof(struct rte_flow_action_set_mac)),
> +	MK_FLOW_ACTION(INC_TCP_SEQ,
> +			sizeof(struct rte_flow_action_modify_tcp_seq)),
> +	MK_FLOW_ACTION(DEC_TCP_SEQ,
> +			sizeof(struct rte_flow_action_modify_tcp_seq)),
> +	MK_FLOW_ACTION(INC_TCP_ACK,
> +			sizeof(struct rte_flow_action_modify_tcp_ack)),
> +	MK_FLOW_ACTION(DEC_TCP_ACK,
> +			sizeof(struct rte_flow_action_modify_tcp_ack)),
>  };
>  
>  static int
> diff --git a/lib/librte_ethdev/rte_flow.h b/lib/librte_ethdev/rte_flow.h
> index c0fe879..74cd03e 100644
> --- a/lib/librte_ethdev/rte_flow.h
> +++ b/lib/librte_ethdev/rte_flow.h
> @@ -1651,6 +1651,46 @@ enum rte_flow_action_type {
>  	 * See struct rte_flow_action_set_mac.
>  	 */
>  	RTE_FLOW_ACTION_TYPE_SET_MAC_DST,
> +
> +	/**
> +	 * Increase sequence number in the outermost TCP header.
> +	 *
> +	 * If flow pattern does not define a valid RTE_FLOW_ITEM_TYPE_TCP,
> +	 * the PMD should return a RTE_FLOW_ERROR_TYPE_ACTION error.

Ditto.

> +	 *
> +	 * See struct rte_flow_action_modify_tcp_seq
> +	 */
> +	RTE_FLOW_ACTION_TYPE_INC_TCP_SEQ,
> +
> +	/**
> +	 * Decrease sequence number in the outermost TCP header.
> +	 *
> +	 * If flow pattern does not define a valid RTE_FLOW_ITEM_TYPE_TCP,
> +	 * the PMD should return a RTE_FLOW_ERROR_TYPE_ACTION error.

Ditto.

> +	 *
> +	 * See struct rte_flow_action_modify_tcp_seq
> +	 */
> +	RTE_FLOW_ACTION_TYPE_DEC_TCP_SEQ,
> +
> +	/**
> +	 * Increase acknowledgment number in the outermost TCP header.
> +	 *
> +	 * If flow pattern does not define a valid RTE_FLOW_ITEM_TYPE_TCP,
> +	 * the PMD should return a RTE_FLOW_ERROR_TYPE_ACTION error.
> +	 *

Ditto.

> +	 * See struct rte_flow_action_modify_tcp_ack
> +	 */
> +	RTE_FLOW_ACTION_TYPE_INC_TCP_ACK,
> +
> +	/**
> +	 * Decrease acknowledgment number in the outermost TCP header.
> +	 *
> +	 * If flow pattern does not define a valid RTE_FLOW_ITEM_TYPE_TCP,
> +	 * the PMD should return a RTE_FLOW_ERROR_TYPE_ACTION error.
> +	 *

Ditto.

> +	 * See struct rte_flow_action_modify_tcp_ack
> +	 */
> +	RTE_FLOW_ACTION_TYPE_DEC_TCP_ACK,
>  };
>  
>  /**
> @@ -2122,6 +2162,26 @@ struct rte_flow_action_set_mac {
>  	uint8_t mac_addr[ETHER_ADDR_LEN];
>  };
>  
> +/**

Experimental tag is missing.

> + * RTE_FLOW_ACTION_TYPE_INC_TCP_SEQ
> + * RTE_FLOW_ACTION_TYPE_DEC_TCP_SEQ
> + *
> + * Increase/Decrease outermost TCP's sequence number

Suggestion:

 Increase/decrease outermost TCP sequence number.

> + */
> +struct rte_flow_action_modify_tcp_seq {
> +	rte_be32_t value;

Field documentation is mandatory, e.g.:

 rte_be32_t value; /**< Value to add/subtract. */

Beside, I'm not sure this value should be big endian since it's not stored
as is in the TCP header; it's used by the host system to compute a new
value.

Also what about having another field to specify what needs to be done with
this value (e.g. add/sub/set - in which case big endian makes sense) to
reduce the number of new actions? Something like:

 struct rte_flow_action_mod_tcp_seq {
     enum rte_flow_action_mod_tcp_seq_op {
         RTE_FLOW_ACTION_MOD_TCP_SEQ_OP_ADD,
         RTE_FLOW_ACTION_MOD_TCP_SEQ_OP_SUB,
         RTE_FLOW_ACTION_MOD_TCP_SEQ_OP_SET,
     } op; /**< Operation to perform. */
     rte_be32_t value; /**< Value to use with operation. */
 };

> +};
> +
> +/**

Experimental tag also missing.

> + * RTE_FLOW_ACTION_TYPE_INC_TCP_ACK
> + * RTE_FLOW_ACTION_TYPE_DEC_TCP_ACK
> + *
> + * Increase/Decrease TCP's acknowledgment number.

Suggestion:

 Increase/decrease outermost TCP acknowledgment number.

> + */
> +struct rte_flow_action_modify_tcp_ack {
> +	rte_be32_t value;

Field documentation also missing.

> +};
> +
>  /*
>   * Definition of a single action.
>   *
> -- 
> 1.8.3.1
> 

-- 
Adrien Mazarguil
6WIND