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..  SPDX-License-Identifier: BSD-3-Clause
    Copyright(c) 2017 Intel Corporation.

Flow Classification Library
===========================

DPDK provides a Flow Classification library that provides the ability
to classify an input packet by matching it against a set of Flow rules.

The initial implementation supports counting of IPv4 5-tuple packets which match
a particular Flow rule only.

Please refer to the
:doc:`./rte_flow`
for more information.

The Flow Classification library uses the ``librte_table`` API for managing Flow
rules and matching packets against the Flow rules.
The library is table agnostic and can use the following tables:
``Access Control List``, ``Hash`` and ``Longest Prefix Match(LPM)``.
The ``Access Control List`` table is used in the initial implementation.

Please refer to the
:doc:`./packet_framework`
for more information.on ``librte_table``.

DPDK provides an Access Control List library that provides the ability to
classify an input packet based on a set of classification rules.

Please refer to the
:doc:`./packet_classif_access_ctrl`
library for more information on ``librte_acl``.

There is also a Flow Classify sample application which demonstrates the use of
the Flow Classification Library API's.

Please refer to the
:doc:`../sample_app_ug/flow_classify`
for more information on the ``flow_classify`` sample application.

Overview
--------

The library has the following API's

.. code-block:: c

    /**
     * Flow classifier create
     *
     * @param params
     *   Parameters for flow classifier creation
     * @return
     *   Handle to flow classifier instance on success or NULL otherwise
     */
    struct rte_flow_classifier *
    rte_flow_classifier_create(struct rte_flow_classifier_params *params);

    /**
     * Flow classifier free
     *
     * @param cls
     *   Handle to flow classifier instance
     * @return
     *   0 on success, error code otherwise
     */
    int
    rte_flow_classifier_free(struct rte_flow_classifier *cls);

    /**
     * Flow classify table create
     *
     * @param cls
     *   Handle to flow classifier instance
     * @param params
     *   Parameters for flow_classify table creation
     * @return
     *   0 on success, error code otherwise
     */
    int
    rte_flow_classify_table_create(struct rte_flow_classifier *cls,
           struct rte_flow_classify_table_params *params);

    /**
     * Validate the flow classify rule
     *
     * @param[in] cls
     *   Handle to flow classifier instance
     * @param[in] attr
     *   Flow rule attributes
     * @param[in] pattern
     *   Pattern specification (list terminated by the END pattern item).
     * @param[in] actions
     *   Associated actions (list terminated by the END pattern item).
     * @param[out] error
     *   Perform verbose error reporting if not NULL. Structure
     *   initialised in case of error only.
     * @return
     *   0 on success, error code otherwise
     */
    int
    rte_flow_classify_validate(struct rte_flow_classifier *cls,
            const struct rte_flow_attr *attr,
            const struct rte_flow_item pattern[],
            const struct rte_flow_action actions[],
            struct rte_flow_error *error);

    /**
     * Add a flow classify rule to the flow_classifier table.
     *
     * @param[in] cls
     *   Flow classifier handle
     * @param[in] attr
     *   Flow rule attributes
     * @param[in] pattern
     *   Pattern specification (list terminated by the END pattern item).
     * @param[in] actions
     *   Associated actions (list terminated by the END pattern item).
     * @param[out] key_found
     *   returns 1 if rule present already, 0 otherwise.
     * @param[out] error
     *   Perform verbose error reporting if not NULL. Structure
     *   initialised in case of error only.
     * @return
     *   A valid handle in case of success, NULL otherwise.
     */
    struct rte_flow_classify_rule *
    rte_flow_classify_table_entry_add(struct rte_flow_classifier *cls,
            const struct rte_flow_attr *attr,
            const struct rte_flow_item pattern[],
            const struct rte_flow_action actions[],
            int *key_found;
            struct rte_flow_error *error);

    /**
     * Delete a flow classify rule from the flow_classifier table.
     *
     * @param[in] cls
     *   Flow classifier handle
     * @param[in] rule
     *   Flow classify rule
     * @return
     *   0 on success, error code otherwise.
     */
    int
    rte_flow_classify_table_entry_delete(struct rte_flow_classifier *cls,
            struct rte_flow_classify_rule *rule);

    /**
     * Query flow classifier for given rule.
     *
     * @param[in] cls
     *   Flow classifier handle
     * @param[in] pkts
     *   Pointer to packets to process
     * @param[in] nb_pkts
     *   Number of packets to process
     * @param[in] rule
     *   Flow classify rule
     * @param[in] stats
     *   Flow classify stats
     *
     * @return
     *   0 on success, error code otherwise.
     */
    int
    rte_flow_classifier_query(struct rte_flow_classifier *cls,
            struct rte_mbuf **pkts,
            const uint16_t nb_pkts,
            struct rte_flow_classify_rule *rule,
            struct rte_flow_classify_stats *stats);

Classifier creation
~~~~~~~~~~~~~~~~~~~

The application creates the ``Classifier`` using the
``rte_flow_classifier_create`` API.
The ``rte_flow_classify_params`` structure must be initialised by the
application before calling the API.

.. code-block:: c

    struct rte_flow_classifier_params {
        /** flow classifier name */
        const char *name;

        /** CPU socket ID where memory for the flow classifier and its */
        /** elements (tables) should be allocated */
        int socket_id;
    };

The ``Classifier`` has the following internal structures:

.. code-block:: c

    struct rte_cls_table {
        /* Input parameters */
        struct rte_table_ops ops;
        uint32_t entry_size;
        enum rte_flow_classify_table_type type;

        /* Handle to the low-level table object */
        void *h_table;
    };

    #define RTE_FLOW_CLASSIFIER_MAX_NAME_SZ 256

    struct rte_flow_classifier {
        /* Input parameters */
        char name[RTE_FLOW_CLASSIFIER_MAX_NAME_SZ];
        int socket_id;

        /* Internal */
        /* ntuple_filter */
        struct rte_eth_ntuple_filter ntuple_filter;

        /* classifier tables */
        struct rte_cls_table tables[RTE_FLOW_CLASSIFY_TABLE_MAX];
        uint32_t table_mask;
        uint32_t num_tables;

        uint16_t nb_pkts;
        struct rte_flow_classify_table_entry
            *entries[RTE_PORT_IN_BURST_SIZE_MAX];
    } __rte_cache_aligned;

Adding a table to the Classifier
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The application adds a table to the ``Classifier`` using the
``rte_flow_classify_table_create`` API.
The ``rte_flow_classify_table_params`` structure must be initialised by the
application before calling the API.

.. code-block:: c

    struct rte_flow_classify_table_params {
        /** Table operations (specific to each table type) */
        struct rte_table_ops *ops;

        /** Opaque param to be passed to the table create operation */
        void *arg_create;

        /** Classifier table type */
        enum rte_flow_classify_table_type type;
     };

To create an ACL table the ``rte_table_acl_params`` structure must be
initialised and assigned to ``arg_create`` in the
``rte_flow_classify_table_params`` structure.

.. code-block:: c

    struct rte_table_acl_params {
        /** Name */
        const char *name;

        /** Maximum number of ACL rules in the table */
        uint32_t n_rules;

        /** Number of fields in the ACL rule specification */
        uint32_t n_rule_fields;

        /** Format specification of the fields of the ACL rule */
        struct rte_acl_field_def field_format[RTE_ACL_MAX_FIELDS];
    };

The fields for the ACL rule must also be initialised by the application.

An ACL table can be added to the ``Classifier`` for each ACL rule, for example
another table could be added for the IPv6 5-tuple rule.

Flow Parsing
~~~~~~~~~~~~

The library currently supports three IPv4 5-tuple flow patterns, for UDP, TCP
and SCTP.

.. code-block:: c

    /* Pattern for IPv4 5-tuple UDP filter */
    static enum rte_flow_item_type pattern_ntuple_1[] = {
        RTE_FLOW_ITEM_TYPE_ETH,
        RTE_FLOW_ITEM_TYPE_IPV4,
        RTE_FLOW_ITEM_TYPE_UDP,
        RTE_FLOW_ITEM_TYPE_END,
    };

    /* Pattern for IPv4 5-tuple TCP filter */
    static enum rte_flow_item_type pattern_ntuple_2[] = {
        RTE_FLOW_ITEM_TYPE_ETH,
        RTE_FLOW_ITEM_TYPE_IPV4,
        RTE_FLOW_ITEM_TYPE_TCP,
        RTE_FLOW_ITEM_TYPE_END,
    };

    /* Pattern for IPv4 5-tuple SCTP filter */
    static enum rte_flow_item_type pattern_ntuple_3[] = {
        RTE_FLOW_ITEM_TYPE_ETH,
        RTE_FLOW_ITEM_TYPE_IPV4,
        RTE_FLOW_ITEM_TYPE_SCTP,
        RTE_FLOW_ITEM_TYPE_END,
    };

The API function ``rte_flow_classify_validate`` parses the
IPv4 5-tuple pattern, attributes and actions and returns the 5-tuple data in the
``rte_eth_ntuple_filter`` structure.

.. code-block:: c

    static int
    rte_flow_classify_validate(struct rte_flow_classifier *cls,
                   const struct rte_flow_attr *attr,
                   const struct rte_flow_item pattern[],
                   const struct rte_flow_action actions[],
                   struct rte_flow_error *error)

Adding Flow Rules
~~~~~~~~~~~~~~~~~

The ``rte_flow_classify_table_entry_add`` API creates an
``rte_flow_classify`` object which contains the flow_classify id and type, the
action, a union of add and delete keys and a union of rules.
It uses the ``rte_flow_classify_validate`` API function for parsing the
flow parameters.
The 5-tuple ACL key data is obtained from the ``rte_eth_ntuple_filter``
structure populated by the ``classify_parse_ntuple_filter`` function which
parses the Flow rule.

.. code-block:: c

    struct acl_keys {
        struct rte_table_acl_rule_add_params key_add; /* add key */
        struct rte_table_acl_rule_delete_params key_del; /* delete key */
    };

    struct classify_rules {
        enum rte_flow_classify_rule_type type;
        union {
            struct rte_flow_classify_ipv4_5tuple ipv4_5tuple;
        } u;
    };

    struct rte_flow_classify {
        uint32_t id;  /* unique ID of classify object */
        enum rte_flow_classify_table_type tbl_type; /* rule table */
        struct classify_rules rules; /* union of rules */
        union {
            struct acl_keys key;
        } u;
        int key_found; /* rule key found in table */
        struct rte_flow_classify_table_entry entry;  /* rule meta data */
        void *entry_ptr; /* handle to the table entry for rule meta data */
    };

It then calls the ``table.ops.f_add`` API to add the rule to the ACL
table.

Deleting Flow Rules
~~~~~~~~~~~~~~~~~~~

The ``rte_flow_classify_table_entry_delete`` API calls the
``table.ops.f_delete`` API to delete a rule from the ACL table.

Packet Matching
~~~~~~~~~~~~~~~

The ``rte_flow_classifier_query`` API is used to find packets which match a
given flow Flow rule in the table.
This API calls the flow_classify_run internal function which calls the
``table.ops.f_lookup`` API to see if any packets in a burst match any
of the Flow rules in the table.
The meta data for the highest priority rule matched for each packet is returned
in the entries array in the ``rte_flow_classify`` object.
The internal function ``action_apply`` implements the ``Count`` action which is
used to return data which matches a particular Flow rule.

The rte_flow_classifier_query API uses the following structures to return data
to the application.

.. code-block:: c

    /** IPv4 5-tuple data */
    struct rte_flow_classify_ipv4_5tuple {
        uint32_t dst_ip;         /**< Destination IP address in big endian. */
        uint32_t dst_ip_mask;    /**< Mask of destination IP address. */
        uint32_t src_ip;         /**< Source IP address in big endian. */
        uint32_t src_ip_mask;    /**< Mask of destination IP address. */
        uint16_t dst_port;       /**< Destination port in big endian. */
        uint16_t dst_port_mask;  /**< Mask of destination port. */
        uint16_t src_port;       /**< Source Port in big endian. */
        uint16_t src_port_mask;  /**< Mask of source port. */
        uint8_t proto;           /**< L4 protocol. */
        uint8_t proto_mask;      /**< Mask of L4 protocol. */
    };

    /**
     * Flow stats
     *
     * For the count action, stats can be returned by the query API.
     *
     * Storage for stats is provided by the application.
     *
     *
     */
    struct rte_flow_classify_stats {
        void *stats;
    };

    struct rte_flow_classify_5tuple_stats {
        /** count of packets that match IPv4 5tuple pattern */
        uint64_t counter1;
        /** IPv4 5tuple data */
        struct rte_flow_classify_ipv4_5tuple ipv4_5tuple;
    };