dpif-provider.h

/*
 * Copyright (c) 2009, 2010, 2011, 2012, 2013 Nicira, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at:
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#ifndef DPIF_PROVIDER_H
#define DPIF_PROVIDER_H 1

/* Provider interface to dpifs, which provide an interface to an Open vSwitch
 * datapath.  A datapath is a collection of physical or virtual ports that are
 * exposed over OpenFlow as a single switch.  Datapaths and the collections of
 * ports that they contain may be fixed or dynamic. */

#include "openflow/openflow.h"
#include "dpif.h"
#include "util.h"

#ifdef  __cplusplus
extern "C" {
#endif

/* Open vSwitch datapath interface.
 *
 * This structure should be treated as opaque by dpif implementations. */
struct dpif {
    const struct dpif_class *dpif_class;
    char *base_name;
    char *full_name;
    uint8_t netflow_engine_type;
    uint8_t netflow_engine_id;
};

void dpif_init(struct dpif *, const struct dpif_class *, const char *name,
               uint8_t netflow_engine_type, uint8_t netflow_engine_id);
void dpif_uninit(struct dpif *dpif, bool close);

static inline void dpif_assert_class(const struct dpif *dpif,
                                     const struct dpif_class *dpif_class)
{
    ovs_assert(dpif->dpif_class == dpif_class);
}

/* Datapath interface class structure, to be defined by each implementation of
 * a datapath interface.
 *
 * These functions return 0 if successful or a positive errno value on failure,
 * except where otherwise noted.
 *
 * These functions are expected to execute synchronously, that is, to block as
 * necessary to obtain a result.  Thus, they may not return EAGAIN or
 * EWOULDBLOCK or EINPROGRESS.  We may relax this requirement in the future if
 * and when we encounter performance problems. */
struct dpif_class {
    /* Type of dpif in this class, e.g. "system", "netdev", etc.
     *
     * One of the providers should supply a "system" type, since this is
     * the type assumed if no type is specified when opening a dpif. */
    const char *type;

    /* Enumerates the names of all known created datapaths, if possible, into
     * 'all_dps'.  The caller has already initialized 'all_dps' and other dpif
     * classes might already have added names to it.
     *
     * This is used by the vswitch at startup, so that it can delete any
     * datapaths that are not configured.
     *
     * Some kinds of datapaths might not be practically enumerable, in which
     * case this function may be a null pointer. */
    int (*enumerate)(struct sset *all_dps);

    /* Returns the type to pass to netdev_open() when a dpif of class
     * 'dpif_class' has a port of type 'type', for a few special cases
     * when a netdev type differs from a port type.  For example, when
     * using the userspace datapath, a port of type "internal" needs to
     * be opened as "tap".
     *
     * Returns either 'type' itself or a string literal, which must not
     * be freed. */
    const char *(*port_open_type)(const struct dpif_class *dpif_class,
                                  const char *type);

    /* Attempts to open an existing dpif called 'name', if 'create' is false,
     * or to open an existing dpif or create a new one, if 'create' is true.
     *
     * 'dpif_class' is the class of dpif to open.
     *
     * If successful, stores a pointer to the new dpif in '*dpifp', which must
     * have class 'dpif_class'.  On failure there are no requirements on what
     * is stored in '*dpifp'. */
    int (*open)(const struct dpif_class *dpif_class,
                const char *name, bool create, struct dpif **dpifp);

    /* Closes 'dpif' and frees associated memory. */
    void (*close)(struct dpif *dpif);

    /* Attempts to destroy the dpif underlying 'dpif'.
     *
     * If successful, 'dpif' will not be used again except as an argument for
     * the 'close' member function. */
    int (*destroy)(struct dpif *dpif);

    /* Performs periodic work needed by 'dpif', if any is necessary. */
    void (*run)(struct dpif *dpif);

    /* Arranges for poll_block() to wake up if the "run" member function needs
     * to be called for 'dpif'. */
    void (*wait)(struct dpif *dpif);

    /* Retrieves statistics for 'dpif' into 'stats'. */
    int (*get_stats)(const struct dpif *dpif, struct dpif_dp_stats *stats);

    /* Adds 'netdev' as a new port in 'dpif'.  If '*port_no' is not
     * UINT32_MAX, attempts to use that as the port's port number.
     *
     * If port is successfully added, sets '*port_no' to the new port's
     * port number.  Returns EBUSY if caller attempted to choose a port
     * number, and it was in use. */
    int (*port_add)(struct dpif *dpif, struct netdev *netdev,
                    odp_port_t *port_no);

    /* Removes port numbered 'port_no' from 'dpif'. */
    int (*port_del)(struct dpif *dpif, odp_port_t port_no);

    /* Queries 'dpif' for a port with the given 'port_no' or 'devname'.
     * If 'port' is not null, stores information about the port into
     * '*port' if successful.
     *
     * If 'port' is not null, the caller takes ownership of data in
     * 'port' and must free it with dpif_port_destroy() when it is no
     * longer needed. */
    int (*port_query_by_number)(const struct dpif *dpif, odp_port_t port_no,
                                struct dpif_port *port);
    int (*port_query_by_name)(const struct dpif *dpif, const char *devname,
                              struct dpif_port *port);

    /* Returns the Netlink PID value to supply in OVS_ACTION_ATTR_USERSPACE
     * actions as the OVS_USERSPACE_ATTR_PID attribute's value, for use in
     * flows whose packets arrived on port 'port_no'.  In the case where the
     * provider allocates multiple Netlink PIDs to a single port, it may use
     * 'hash' to spread load among them.  The caller need not use a particular
     * hash function; a 5-tuple hash is suitable.
     *
     * (The datapath implementation might use some different hash function for
     * distributing packets received via flow misses among PIDs.  This means
     * that packets received via flow misses might be reordered relative to
     * packets received via userspace actions.  This is not ordinarily a
     * problem.)
     *
     * A 'port_no' of UINT32_MAX should be treated as a special case.  The
     * implementation should return a reserved PID, not allocated to any port,
     * that the client may use for special purposes.
     *
     * The return value only needs to be meaningful when DPIF_UC_ACTION has
     * been enabled in the 'dpif''s listen mask, and it is allowed to change
     * when DPIF_UC_ACTION is disabled and then re-enabled.
     *
     * A dpif provider that doesn't have meaningful Netlink PIDs can use NULL
     * for this function.  This is equivalent to always returning 0. */
    uint32_t (*port_get_pid)(const struct dpif *dpif, odp_port_t port_no,
                             uint32_t hash);

    /* Attempts to begin dumping the ports in a dpif.  On success, returns 0
     * and initializes '*statep' with any data needed for iteration.  On
     * failure, returns a positive errno value. */
    int (*port_dump_start)(const struct dpif *dpif, void **statep);

    /* Attempts to retrieve another port from 'dpif' for 'state', which was
     * initialized by a successful call to the 'port_dump_start' function for
     * 'dpif'.  On success, stores a new dpif_port into 'port' and returns 0.
     * Returns EOF if the end of the port table has been reached, or a positive
     * errno value on error.  This function will not be called again once it
     * returns nonzero once for a given iteration (but the 'port_dump_done'
     * function will be called afterward).
     *
     * The dpif provider retains ownership of the data stored in 'port'.  It
     * must remain valid until at least the next call to 'port_dump_next' or
     * 'port_dump_done' for 'state'. */
    int (*port_dump_next)(const struct dpif *dpif, void *state,
                          struct dpif_port *port);

    /* Releases resources from 'dpif' for 'state', which was initialized by a
     * successful call to the 'port_dump_start' function for 'dpif'.  */
    int (*port_dump_done)(const struct dpif *dpif, void *state);

    /* Polls for changes in the set of ports in 'dpif'.  If the set of ports in
     * 'dpif' has changed, then this function should do one of the
     * following:
     *
     * - Preferably: store the name of the device that was added to or deleted
     *   from 'dpif' in '*devnamep' and return 0.  The caller is responsible
     *   for freeing '*devnamep' (with free()) when it no longer needs it.
     *
     * - Alternatively: return ENOBUFS, without indicating the device that was
     *   added or deleted.
     *
     * Occasional 'false positives', in which the function returns 0 while
     * indicating a device that was not actually added or deleted or returns
     * ENOBUFS without any change, are acceptable.
     *
     * If the set of ports in 'dpif' has not changed, returns EAGAIN.  May also
     * return other positive errno values to indicate that something has gone
     * wrong. */
    int (*port_poll)(const struct dpif *dpif, char **devnamep);

    /* Arranges for the poll loop to wake up when 'port_poll' will return a
     * value other than EAGAIN. */
    void (*port_poll_wait)(const struct dpif *dpif);

    /* Queries 'dpif' for a flow entry.  The flow is specified by the Netlink
     * attributes with types OVS_KEY_ATTR_* in the 'key_len' bytes starting at
     * 'key'.
     *
     * Returns 0 if successful.  If no flow matches, returns ENOENT.  On other
     * failure, returns a positive errno value.
     *
     * If 'actionsp' is nonnull, then on success '*actionsp' must be set to an
     * ofpbuf owned by the caller that contains the Netlink attributes for the
     * flow's actions.  The caller must free the ofpbuf (with ofpbuf_delete())
     * when it is no longer needed.
     *
     * If 'stats' is nonnull, then on success it must be updated with the
     * flow's statistics. */
    int (*flow_get)(const struct dpif *dpif,
                    const struct nlattr *key, size_t key_len,
                    struct ofpbuf **actionsp, struct dpif_flow_stats *stats);

    /* Adds or modifies a flow in 'dpif'.  The flow is specified by the Netlink
     * attributes with types OVS_KEY_ATTR_* in the 'put->key_len' bytes
     * starting at 'put->key'.  The associated actions are specified by the
     * Netlink attributes with types OVS_ACTION_ATTR_* in the
     * 'put->actions_len' bytes starting at 'put->actions'.
     *
     * - If the flow's key does not exist in 'dpif', then the flow will be
     *   added if 'put->flags' includes DPIF_FP_CREATE.  Otherwise the
     *   operation will fail with ENOENT.
     *
     *   If the operation succeeds, then 'put->stats', if nonnull, must be
     *   zeroed.
     *
     * - If the flow's key does exist in 'dpif', then the flow's actions will
     *   be updated if 'put->flags' includes DPIF_FP_MODIFY.  Otherwise the
     *   operation will fail with EEXIST.  If the flow's actions are updated,
     *   then its statistics will be zeroed if 'put->flags' includes
     *   DPIF_FP_ZERO_STATS, and left as-is otherwise.
     *
     *   If the operation succeeds, then 'put->stats', if nonnull, must be set
     *   to the flow's statistics before the update.
     */
    int (*flow_put)(struct dpif *dpif, const struct dpif_flow_put *put);

    /* Deletes a flow from 'dpif' and returns 0, or returns ENOENT if 'dpif'
     * does not contain such a flow.  The flow is specified by the Netlink
     * attributes with types OVS_KEY_ATTR_* in the 'del->key_len' bytes
     * starting at 'del->key'.
     *
     * If the operation succeeds, then 'del->stats', if nonnull, must be set to
     * the flow's statistics before its deletion. */
    int (*flow_del)(struct dpif *dpif, const struct dpif_flow_del *del);

    /* Deletes all flows from 'dpif' and clears all of its queues of received
     * packets. */
    int (*flow_flush)(struct dpif *dpif);

    /* Allocates thread-local state for use with the function 'flow_dump_next'.
     * On return, initializes '*statep' with any private data needed for
     * iteration. */
    void (*flow_dump_state_init)(void **statep);

    /* Attempts to begin dumping the flows in a dpif.  On success, returns 0
     * and initializes '*iterp' with any shared data needed for iteration.
     * On failure, returns a positive errno value. */
    int (*flow_dump_start)(const struct dpif *dpif, void **iterp);

    /* Attempts to retrieve another flow from 'dpif' for 'iter', using
     * 'state' for storage. 'iter' must have been initialized by a successful
     * call to the 'flow_dump_start' function for 'dpif'. 'state' must have
     * been initialised with a call to the 'flow_dump_state_init' function for
     * 'dpif.
     *
     * On success, updates the output parameters as described below and returns
     * 0. Returns EOF if the end of the flow table has been reached, or a
     * positive errno value on error. Multiple threads may use the same 'dpif'
     * and 'iter' with this function, but all other parameters must be
     * different for each thread. If this function returns non-zero,
     * subsequent calls with the same arguments will also return non-zero.
     *
     * On success:
     *
     *     - If 'key' and 'key_len' are nonnull, then '*key' and '*key_len'
     *       must be set to Netlink attributes with types OVS_KEY_ATTR_*
     *       representing the dumped flow's key.
     *
     *     - If 'mask' and 'mask_len' are nonnull then '*mask' and '*mask_len'
     *       must be set to Netlink attributes with types of OVS_KEY_ATTR_*
     *       representing the dumped flow's mask.
     *
     *     - If 'actions' and 'actions_len' are nonnull then they should be set
     *       to Netlink attributes with types OVS_ACTION_ATTR_* representing
     *       the dumped flow's actions.
     *
     *     - If 'stats' is nonnull then it should be set to the dumped flow's
     *       statistics.
     *
     * All of the returned data is owned by 'dpif', not by the caller, and the
     * caller must not modify or free it.  'dpif' must guarantee that it
     * remains accessible and unchanging until at least the next call to
     * 'flow_dump_next' or 'flow_dump_done' for 'iter' and 'state'. */
    int (*flow_dump_next)(const struct dpif *dpif, void *iter, void *state,
                          const struct nlattr **key, size_t *key_len,
                          const struct nlattr **mask, size_t *mask_len,
                          const struct nlattr **actions, size_t *actions_len,
                          const struct dpif_flow_stats **stats);

    /* Determines whether the next call to 'flow_dump_next' with 'state' will
     * modify or free the keys that it previously returned. 'state' must have
     * been initialized by a call to 'flow_dump_state_init' for 'dpif'.
     *
     * 'dpif' guarantees that data returned by flow_dump_next() will remain
     * accessible and unchanging until the next call. This function provides a
     * way for callers to determine whether that guarantee extends beyond the
     * next call.
     *
     * Returns true if the next call to flow_dump_next() is expected to be
     * destructive to previously returned keys for 'state', false otherwise. */
    bool (*flow_dump_next_may_destroy_keys)(void *state);

    /* Releases resources from 'dpif' for 'iter', which was initialized by a
     * successful call to the 'flow_dump_start' function for 'dpif'. Callers
     * must ensure that this function is called once within a given iteration,
     * as the final flow dump operation. */
    int (*flow_dump_done)(const struct dpif *dpif, void *iter);

    /* Releases 'state' which was initialized by a call to the
     * 'flow_dump_state_init' function for this 'dpif'. */
    void (*flow_dump_state_uninit)(void *statep);

    /* Performs the 'execute->actions_len' bytes of actions in
     * 'execute->actions' on the Ethernet frame in 'execute->packet'
     * and on the packet metadata in 'execute->md'.
     * May modify both packet and metadata. */
    int (*execute)(struct dpif *dpif, struct dpif_execute *execute);

    /* Executes each of the 'n_ops' operations in 'ops' on 'dpif', in the order
     * in which they are specified, placing each operation's results in the
     * "output" members documented in comments.
     *
     * This function is optional.  It is only worthwhile to implement it if
     * 'dpif' can perform operations in batch faster than individually. */
    void (*operate)(struct dpif *dpif, struct dpif_op **ops, size_t n_ops);

    /* Enables or disables receiving packets with dpif_recv() for 'dpif'.
     * Turning packet receive off and then back on is allowed to change Netlink
     * PID assignments (see ->port_get_pid()).  The client is responsible for
     * updating flows as necessary if it does this. */
    int (*recv_set)(struct dpif *dpif, bool enable);

    /* Refreshes the poll loops and Netlink sockets associated to each port,
     * when the number of upcall handlers (upcall receiving thread) is changed
     * to 'n_handlers' and receiving packets for 'dpif' is enabled by
     * recv_set().
     *
     * Since multiple upcall handlers can read upcalls simultaneously from
     * 'dpif', each port can have multiple Netlink sockets, one per upcall
     * handler.  So, handlers_set() is responsible for the following tasks:
     *
     *    When receiving upcall is enabled, extends or creates the
     *    configuration to support:
     *
     *        - 'n_handlers' Netlink sockets for each port.
     *
     *        - 'n_handlers' poll loops, one for each upcall handler.
     *
     *        - registering the Netlink sockets for the same upcall handler to
     *          the corresponding poll loop.
     * */
    int (*handlers_set)(struct dpif *dpif, uint32_t n_handlers);

    /* Translates OpenFlow queue ID 'queue_id' (in host byte order) into a
     * priority value used for setting packet priority. */
    int (*queue_to_priority)(const struct dpif *dpif, uint32_t queue_id,
                             uint32_t *priority);

    /* Polls for an upcall from 'dpif' for an upcall handler.  Since there
     * can be multiple poll loops (see ->handlers_set()), 'handler_id' is
     * needed as index to identify the corresponding poll loop.  If
     * successful, stores the upcall into '*upcall', using 'buf' for
     * storage.  Should only be called if 'recv_set' has been used to enable
     * receiving packets from 'dpif'.
     *
     * The implementation should point 'upcall->key' and 'upcall->userdata'
     * (if any) into data in the caller-provided 'buf'.  The implementation may
     * also use 'buf' for storing the data of 'upcall->packet'.  If necessary
     * to make room, the implementation may reallocate the data in 'buf'.
     *
     * The caller owns the data of 'upcall->packet' and may modify it.  If
     * packet's headroom is exhausted as it is manipulated, 'upcall->packet'
     * will be reallocated.  This requires the data of 'upcall->packet' to be
     * released with ofpbuf_uninit() before 'upcall' is destroyed.  However,
     * when an error is returned, the 'upcall->packet' may be uninitialized
     * and should not be released.
     *
     * This function must not block.  If no upcall is pending when it is
     * called, it should return EAGAIN without blocking. */
    int (*recv)(struct dpif *dpif, uint32_t handler_id,
                struct dpif_upcall *upcall, struct ofpbuf *buf);

    /* Arranges for the poll loop for an upcall handler to wake up when 'dpif'
     * has a message queued to be received with the recv member functions.
     * Since there can be multiple poll loops (see ->handlers_set()),
     * 'handler_id' is needed as index to identify the corresponding poll loop.
     * */
    void (*recv_wait)(struct dpif *dpif, uint32_t handler_id);

    /* Throws away any queued upcalls that 'dpif' currently has ready to
     * return. */
    void (*recv_purge)(struct dpif *dpif);
};

extern const struct dpif_class dpif_linux_class;
extern const struct dpif_class dpif_netdev_class;

#ifdef  __cplusplus
}
#endif

#endif /* dpif-provider.h */