dpif-provider.h

/*
 * Copyright (c) 2009, 2010, 2011, 2012 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 <assert.h>
#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)
{
    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);

    /* 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 successful, sets '*port_no'
     * to the new port's port number. */
    int (*port_add)(struct dpif *dpif, struct netdev *netdev,
                    uint16_t *port_no);

    /* Removes port numbered 'port_no' from 'dpif'. */
    int (*port_del)(struct dpif *dpif, uint16_t port_no);

    /* Queries 'dpif' for a port with the given 'port_no' or 'devname'.  Stores
     * information about the port into '*port' if successful.
     *
     * 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, uint16_t port_no,
                                struct dpif_port *port);
    int (*port_query_by_name)(const struct dpif *dpif, const char *devname,
                              struct dpif_port *port);

    /* Returns one greater than the largest port number accepted in flow
     * actions. */
    int (*get_max_ports)(const struct dpif *dpif);

    /* 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'.
     *
     * A 'port_no' of UINT16_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, uint16_t port_no);

    /* 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);

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

    /* Attempts to retrieve another flow from 'dpif' for 'state', which was
     * initialized by a successful call to the 'flow_dump_start' 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.  This function will not be
     * called again once it returns nonzero within a given iteration (but the
     * 'flow_dump_done' function will be called afterward).
     *
     * 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 '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 'state'. */
    int (*flow_dump_next)(const struct dpif *dpif, void *state,
                          const struct nlattr **key, size_t *key_len,
                          const struct nlattr **actions, size_t *actions_len,
                          const struct dpif_flow_stats **stats);

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

    /* Performs the 'execute->actions_len' bytes of actions in
     * 'execute->actions' on the Ethernet frame specified in 'execute->packet'
     * taken from the flow specified in the 'execute->key_len' bytes of
     * 'execute->key'.  ('execute->key' is mostly redundant with
     * 'execute->packet', but it contains some metadata that cannot be
     * recovered from 'execute->packet', such as tun_id and in_port.) */
    int (*execute)(struct dpif *dpif, const 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);

    /* 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'.  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->packet' and 'upcall->key' into
     * data in the caller-provided 'buf'.  If necessary to make room, the
     * implementation may expand the data in 'buf'.  (This is hardly a great
     * way to do things but it works out OK for the dpif providers that exist
     * so far.)
     *
     * 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, struct dpif_upcall *upcall,
                struct ofpbuf *buf);

    /* Arranges for the poll loop to wake up when 'dpif' has a message queued
     * to be received with the recv member function. */
    void (*recv_wait)(struct dpif *dpif);

    /* 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 */