rlm_cache.h

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#pragma once
/*
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation; either version 2 of the License, or (at
 *   your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program; if not, write to the Free Software
 *   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
 */
 
/*
 * $Id: 7915bb91ec36f02cb9e12c7cc4809c282a3c33b1 $
 * @file rlm_cache.h
 * @brief Cache values and merge them back into future requests.
 *
 * @copyright 2014 The FreeRADIUS server project
 * @copyright 2014 Arran Cudbard-Bell (a.cudbardb@freeradius.org)
 */
RCSIDH(cache_h, "$Id: 7915bb91ec36f02cb9e12c7cc4809c282a3c33b1 $")
 
#include <freeradius-devel/server/base.h>
#include <freeradius-devel/server/dl_module.h>
#include <freeradius-devel/server/map.h>
#include <freeradius-devel/protocol/freeradius/freeradius.internal.h>
 
typedef struct rlm_cache_driver_s rlm_cache_driver_t;
 
typedef void rlm_cache_handle_t;
 
#define MAX_ATTRMAP     128
 
typedef enum {
        CACHE_RECONNECT = -2,                           //!< Handle needs to be reconnected
        CACHE_ERROR     = -1,                           //!< Fatal error
        CACHE_OK        = 0,                            //!< Cache entry found/updated
        CACHE_MISS      = 1                             //!< Cache entry notfound
} cache_status_t;
 
/** Configuration for the rlm_cache module
 *
 * This is separate from the #rlm_cache_t struct, to limit driver's visibility of
 * rlm_cache instance data.
 */
typedef struct {
        fr_time_delta_t         ttl;                    //!< How long an entry is valid for.
        uint32_t                max_entries;            //!< Maximum entries allowed.
        int32_t                 epoch;                  //!< Time after which entries are considered valid.
        bool                    stats;                  //!< Generate statistics.
} rlm_cache_config_t;
 
/*
 *      Define a structure for our module configuration.
 *
 *      These variables do not need to be in a structure, but it's
 *      a lot cleaner to do so, and a pointer to the structure can
 *      be used as the instance handle.
 */
typedef struct {
        rlm_cache_config_t      config;                 //!< Must come first because of icky hacks.
 
        module_instance_t       *driver_submodule;      //!< Driver's instance data.
        rlm_cache_driver_t const *driver;               //!< Driver's exported interface.
} rlm_cache_t;
 
typedef struct {
        fr_value_box_t          key;                    //!< Key used to identify entry.
        long long int           hits;                   //!< How many times the entry has been retrieved.
        fr_unix_time_t          created;                //!< When the entry was created.
        fr_unix_time_t          expires;                //!< When the entry expires.
 
        map_list_t              maps;                   //!< Head of the maps list.
} rlm_cache_entry_t;
 
/** Allocate a new cache entry
 *
 */
typedef rlm_cache_entry_t *(*cache_entry_alloc_t)(rlm_cache_config_t const *config, void *instance, request_t *request);
 
/** Free a cache entry
 *
 * @note This callback is optional, but the driver assume responsibility for freeing the
 *      cache_entry_t on #cache_entry_expire_t.
 *
 * If the driver does not need to keep a local copy of the cache entry, it should provide
 * a callback to free the memory previously allocated for the cache entry by
 * #cache_entry_find_t or by rlm_cache.
 *
 * @param c entry to free.
 */
typedef void            (*cache_entry_free_t)(rlm_cache_entry_t *c);
 
/** Retrieve an entry from the cache
 *
 * If a cache entry is found, but the cache entry needs to be deserialized, the driver
 * is expected to allocate an appropriately sized #rlm_cache_entry_t, perform the deserialisation,
 * and write a pointer to the new entry to out, returning #CACHE_OK.
 *
 * If the #rlm_cache_handle_t is inviable, the driver should return #CACHE_RECONNECT, to have
 * it reinitialised/reconnected.
 *
 * @param[out] out Where to write a pointer to the retrieved entry (if there was one).
 * @param[in] config for this instance of the rlm_cache module.
 * @param[in] instance Driver specific instance data.
 * @param[in] request The current request.
 * @param[in] handle the driver gave us when we called #cache_acquire_t, or NULL if no
 *      #cache_acquire_t callback was provided.
 * @param[in] key to use to lookup cache entry
 * @return
 *      - #CACHE_RECONNECT - If handle needs to be reinitialised/reconnected.
 *      - #CACHE_ERROR - If the lookup couldn't be completed.
 *      - #CACHE_OK - Lookup was successful.
 *      - #CACHE_MISS - No cached entry was found.
 */
typedef cache_status_t  (*cache_entry_find_t)(rlm_cache_entry_t **out, rlm_cache_config_t const *config,
                                              void *instance, request_t *request, void *handle,
                                              fr_value_box_t const *key);
 
/** Insert an entry into the cache
 *
 * Serialize (if necessary) the entry passed to us, and write it to the cache with
 * the key c->key.
 *
 * The cache entry should not be freed by the driver, irrespective of success or failure.
 * If the entry needs to be freed after insertion because a local copy should not be kept,
 * the driver should provide a #cache_entry_free_t callback.
 *
 * If the #rlm_cache_handle_t is inviable, the driver should return #CACHE_RECONNECT, to have
 * it reinitialised/reconnected.
 *
 * @note This callback is not optional.
 *
 * @note This callback *must* overwrite existing cache entries on insert.
 *
 * @param config for this instance of the rlm_cache module.
 * @param instance Driver specific instance data.
 * @param request The current request.
 * @param handle the driver gave us when we called #cache_acquire_t, or NULL if no
 *      #cache_acquire_t callback was provided.
 * @param c to insert.
 * @return
 *      - #CACHE_RECONNECT - If handle needs to be reinitialised/reconnected.
 *      - #CACHE_ERROR - If the insert couldn't be completed.
 *      - #CACHE_OK - If the insert was successful.
 */
typedef cache_status_t  (*cache_entry_insert_t)(rlm_cache_config_t const *config, void *instance,
                                                request_t *request, void *handle,
                                                rlm_cache_entry_t const *c);
 
/** Remove an entry from the cache
 *
 * @note This callback is not optional.
 *
 * @param[in] config for this instance of the rlm_cache module.
 * @param[in] instance Driver specific instance data.
 * @param[in] request The current request.
 * @param[in] handle the driver gave us when we called #cache_acquire_t, or NULL if no
 *      #cache_acquire_t callback was provided.
 * @param[in] key of entry to expire.
 * @return
 *      - #CACHE_RECONNECT - If handle needs to be reinitialised/reconnected.
 *      - #CACHE_ERROR - If the entry couldn't be expired.
 *      - #CACHE_OK - If the entry was expired.
 *      - #CACHE_MISS - If the entry didn't exist, so couldn't be expired.
 */
typedef cache_status_t  (*cache_entry_expire_t)(rlm_cache_config_t const *config, void *instance,
                                                request_t *request, void *handle,
                                                fr_value_box_t const *key);
 
/** Update the ttl of an entry in the cache
 *
 * @note This callback optional. If it's not specified the cache code will expire and
 *       recreate the entry with a new TTL.
 *
 * If the #rlm_cache_handle_t is inviable, the driver should return #CACHE_RECONNECT, to have
 * it reinitialised/reconnected.
 *
 * @param[in] config for this instance of the rlm_cache module.
 * @param[in] instance Driver specific instance data.
 * @param[in] request The current request.
 * @param[in] handle the driver gave us when we called #cache_acquire_t, or NULL if no
 *      #cache_acquire_t callback was provided.
 * @param[in] c to update the TTL of. c->ttl will have been set to the new value.
 * @return
 *      - #CACHE_RECONNECT - If handle needs to be reinitialised/reconnected.
 *      - #CACHE_ERROR - If the entry TTL couldn't be updated.
 *      - #CACHE_OK - If the entry's TTL was updated.
 */
typedef cache_status_t  (*cache_entry_set_ttl_t)(rlm_cache_config_t const *config, void *instance,
                                                 request_t *request, void *handle,
                                                 rlm_cache_entry_t *c);
 
/** Get the number of entries in the cache
 *
 * @note This callback is optional. Though max_entries will not be enforced if it is not provided.
 *
 * @param[in] config for this instance of the rlm_cache module.
 * @param[in] instance Driver specific instance data.
 * @param[in] request The current request.
 * @param handle the driver gave us when we called #cache_acquire_t, or NULL if no
 *      #cache_acquire_t callback was provided.
 * @return number of entries in the cache.
 */
typedef uint64_t        (*cache_entry_count_t)(rlm_cache_config_t const *config, void *instance,
                                               request_t *request, void *handle);
 
/** Acquire a handle to access the cache
 *
 * @note This callback is optional. If it's not provided the handle argument to other callbacks
 *      will be NULL.
 *
 * @param[out] handle Where to write pointer to handle to access the cache with.
 * @param[in] config for this instance of the rlm_cache module.
 * @param[in] instance Driver specific instance data.
 * @param[in] request The current request.
 * @return
 *      - 0 on success.
 *      - -1 on failure.
 */
typedef int             (*cache_acquire_t)(void **handle, rlm_cache_config_t const *config, void *instance,
                                           request_t *request);
 
/** Release a previously acquired handle
 *
 * @note This callback is optional.
 *
 * @param[in] config for this instance of the rlm_cache module.
 * @param[in] instance Driver specific instance data.
 * @param[in] request The current request.
 * @param[in] handle to release.
 */
typedef void            (*cache_release_t)(rlm_cache_config_t const *config, void *instance, request_t *request,
                                           rlm_cache_handle_t *handle);
 
/** Reconnect a previously acquired handle
 *
 * @note This callback is optional.
 *
 * @param[in,out] handle to reinitialise/reconnect.
 * @param[in] config for this instance of the rlm_cache module.
 * @param[in] instance Driver specific instance data.
 * @param[in] request The current request.
 
 * @return
 *      - 0 on success.
 *      - -1 on failure.
 */
typedef int             (*cache_reconnect_t)(rlm_cache_handle_t **handle, rlm_cache_config_t const *config,
                                             void *instance, request_t *request);
 
struct rlm_cache_driver_s {
        module_t                        common;                 //!< Common fields for all loadable modules.
 
        cache_entry_alloc_t             alloc;                  //!< (optional) Allocate a new entry.
        cache_entry_free_t              free;                   //!< (optional) Free memory used by an entry.
 
        cache_entry_find_t              find;                   //!< Retrieve an existing cache entry.
        cache_entry_insert_t            insert;                 //!< Add a new entry.
        cache_entry_expire_t            expire;                 //!< Remove an old entry.
        cache_entry_set_ttl_t           set_ttl;                //!< (Optional) Update the TTL of an entry.
        cache_entry_count_t             count;                  //!< (Optional) Number of entries currently in
                                                                //!< the cache.
 
        cache_acquire_t                 acquire;                //!< (optional) Acquire exclusive access to a resource
                                                                //!< used to retrieve the cache entry.
        cache_release_t                 release;                //!< (optional) Release access to resource acquired
                                                                //!< with acquire callback.
        cache_reconnect_t               reconnect;              //!< (optional) Re-initialise resource.
 
        call_env_parse_pair_t           key_parse;              //!< (optional) custom key parser.  Allows the driver
                                                                ///< to have complete control over how the key is
                                                                ///< parsed.  If not provided, the default key parser
                                                                ///< will be used.  data will be set to the submodule's
                                                                ///< instance data, NOT the #rlm_cache_t.
};