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

[Dekel Peled <dekelp@mellanox.com>]

Thanks, PSB.

> -----Original Message-----
> From: Adrien Mazarguil <adrien.mazarguil@6wind.com>
> Sent: Friday, March 29, 2019 4:59 PM
> To: Dekel Peled <dekelp@mellanox.com>
> Cc: wenzhuo.lu@intel.com; jingjing.wu@intel.com;
> bernard.iremonger@intel.com; Yongseok Koh <yskoh@mellanox.com>;
> Shahaf Shuler <shahafs@mellanox.com>; dev@dpdk.org; Ori Kam
> <orika@mellanox.com>
> Subject: Re: [PATCH 1/3] ethdev: add actions to modify TCP header fields
> 
> Hi Derek,

It's Dekel, not 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.

Not related to OpenFlow.

> 
> > 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.

I accept, will change it in all relevant locations.

> 
> 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".

Will remove.

> 
> > +
> > +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.

Will add it here and elsewhere.

> 
> > + * 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.

Accepted, will change here and elsewhere.

> 
> > + */
> > +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. */

Will add it.

> 
> 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.

It isn't used by the host, but sent to NIC as part of action.

> 
> 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.

Accepted, will change.

> 
> > + */
> > +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