apache-http-server/modules/ldap/util_ldap_cache.h

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#ifndef APU_LDAP_CACHE_H
#define APU_LDAP_CACHE_H

/*
 * This switches LDAP support on or off.
 */

/* this whole thing disappears if LDAP is not enabled */
#ifdef APU_HAS_LDAP


/*
 * LDAP Cache Manager
 */

#include <apr_shmem.h>

typedef struct util_cache_node_t {
    void *payload;		/* Pointer to the payload */
    time_t add_time;		/* Time node was added to cache */
    struct util_cache_node_t *next;
} util_cache_node_t;

typedef struct util_ald_cache_t {
    unsigned long size;		/* Size of cache array */
    unsigned long maxentries;	/* Maximum number of cache entries */
    unsigned long numentries;	/* Current number of cache entries */
    unsigned long fullmark;	/* Used to keep track of when cache becomes 3/4 full */
    time_t marktime;		/* Time that the cache became 3/4 full */
    unsigned long (*hash)(void *);  /* Func to hash the payload */
    int (*compare)(void *, void *); /* Func to compare two payloads */
    void * (*copy)(void *);	/* Func to alloc mem and copy payload to new mem */
    void (*free)(void *);		/* Func to free mem used by the payload */
    util_cache_node_t **nodes;

    unsigned long numpurges;	/* No. of times the cache has been purged */
    double avg_purgetime;		/* Average time to purge the cache */
    time_t last_purge;		/* Time of the last purge */
    unsigned long npurged;	/* Number of elements purged in last purge. This is not
				   obvious: it won't be 3/4 the size of the cache if 
				   there were a lot of expired entries. */

    unsigned long fetches;	/* Number of fetches */
    unsigned long hits;		/* Number of cache hits */
    unsigned long inserts;	/* Number of inserts */
    unsigned long removes;	/* Number of removes */
} util_ald_cache_t;

#if APR_HAS_SHARED_MEMORY
apr_shmem_t *util_ldap_shm;
#endif
util_ald_cache_t *util_ldap_cache;
apr_lock_t *util_ldap_cache_lock;

#ifndef WIN32
#define ALD_MM_FILE_MODE ( S_IRUSR|S_IWUSR )
#else
#define ALD_MM_FILE_MODE ( _S_IREAD|_S_IWRITE )
#endif


/*
 * LDAP Cache
 */

/*
 * Maintain a cache of LDAP URLs that the server handles. Each node in
 * the cache contains the search cache for that URL, and a compare cache
 * for the URL. The compare cash is populated when doing require group
 * compares.
 */
typedef struct util_url_node_t {
    const char *url;
    util_ald_cache_t *search_cache;
    util_ald_cache_t *compare_cache;
    util_ald_cache_t *dn_compare_cache;
} util_url_node_t;

/*
 * We cache every successful search and bind operation, using the username 
 * as the key. Each node in the cache contains the returned DN, plus the 
 * password used to bind.
 */
typedef struct util_search_node_t {
    const char *username;		/* Cache key */
    const char *dn;			/* DN returned from search */
    const char *bindpw;			/* The most recently used bind password; 
					   NULL if the bind failed */
    apr_time_t lastbind;		/* Time of last successful bind */
    const char **vals;			/* Values of queried attributes */
} util_search_node_t;

/*
 * We cache every successful compare operation, using the DN, attrib, and
 * value as the key. 
 */
typedef struct util_compare_node_t {
    const char *dn;			/* DN, attrib and value combine to be the key */
    const char *attrib;			
    const char *value;
    apr_time_t lastcompare;
    int result;
} util_compare_node_t;

/*
 * We cache every successful compare dn operation, using the dn in the require
 * statement and the dn fetched based on the client-provided username.
 */
typedef struct util_dn_compare_node_t {
    const char *reqdn;		/* The DN in the require dn statement */
    const char *dn;			/* The DN found in the search */
} util_dn_compare_node_t;


/*
 * Function prototypes for LDAP cache
 */

/* util_ldap_cache.c */
unsigned long util_ldap_url_node_hash(void *n);
int util_ldap_url_node_compare(void *a, void *b);
void *util_ldap_url_node_copy(void *c);
void util_ldap_url_node_free(void *n);
unsigned long util_ldap_search_node_hash(void *n);
int util_ldap_search_node_compare(void *a, void *b);
void *util_ldap_search_node_copy(void *c);
void util_ldap_search_node_free(void *n);
unsigned long util_ldap_compare_node_hash(void *n);
int util_ldap_compare_node_compare(void *a, void *b);
void *util_ldap_compare_node_copy(void *c);
void util_ldap_compare_node_free(void *n);
unsigned long util_ldap_dn_compare_node_hash(void *n);
int util_ldap_dn_compare_node_compare(void *a, void *b);
void *util_ldap_dn_compare_node_copy(void *c);
void util_ldap_dn_compare_node_free(void *n);


/* util_ldap_cache_mgr.c */

void util_ald_free(const void *ptr);
void *util_ald_alloc(unsigned long size);
const char *util_ald_strdup(const char *s);
unsigned long util_ald_hash_string(int nstr, ...);
void util_ald_cache_purge(util_ald_cache_t *cache);
util_url_node_t *util_ald_create_caches(util_ldap_state_t *s, const char *url);
util_ald_cache_t *util_ald_create_cache(unsigned long maxentries,
                                unsigned long (*hashfunc)(void *), 
                                int (*comparefunc)(void *, void *),
                                void * (*copyfunc)(void *),
                                void (*freefunc)(void *));
void util_ald_destroy_cache(util_ald_cache_t *cache);
void *util_ald_cache_fetch(util_ald_cache_t *cache, void *payload);
void util_ald_cache_insert(util_ald_cache_t *cache, void *payload);
void util_ald_cache_remove(util_ald_cache_t *cache, void *payload);
char *util_ald_cache_display_stats(apr_pool_t *p, util_ald_cache_t *cache,
                                 char *name);

#endif /* APU_HAS_LDAP */
#endif /* APU_LDAP_CACHE_H */