openldap/libraries/libldap/cache.c
1998-08-09 00:43:13 +00:00

655 lines
15 KiB
C

/*
* Copyright (c) 1993 The Regents of the University of Michigan.
* All rights reserved.
*
* cache.c - local caching support for LDAP
*/
#ifndef NO_CACHE
#ifndef lint
static char copyright[] = "@(#) Copyright (c) 1993 The Regents of the University of Michigan.\nAll rights reserved.\n";
#endif
#include <stdio.h>
#include <string.h>
#ifdef MACOS
#include <stdlib.h>
#include <time.h>
#include "macos.h"
#else /* MACOS */
#if defined( DOS ) || defined( _WIN32 )
#include <malloc.h>
#include "msdos.h"
#ifdef NCSA
#include "externs.h"
#endif /* NCSA */
#ifdef WINSOCK
#include <time.h>
#endif /* WINSOCK */
#else /* DOS */
#include <sys/types.h>
#include <sys/socket.h>
#endif /* DOS */
#endif /* MACOS */
#include "lber.h"
#include "ldap.h"
#include "ldap-int.h"
#ifdef NEEDPROTOS
static int cache_hash( BerElement *ber );
static LDAPMessage *msg_dup( LDAPMessage *msg );
static int request_cmp( BerElement *req1, BerElement *req2 );
static int chain_contains_dn( LDAPMessage *msg, char *dn );
static long msg_size( LDAPMessage *msg );
static void check_cache_memused( LDAPCache *lc );
static void uncache_entry_or_req( LDAP *ld, char *dn, int msgid );
#else /* NEEDPROTOS */
static int cache_hash();
static LDAPMessage *msg_dup();
static int request_cmp();
static int chain_contains_dn();
static long msg_size();
static void check_cache_memused();
static void uncache_entry_or_req();
#endif /* NEEDPROTOS */
int
ldap_enable_cache( LDAP *ld, long timeout, long maxmem )
{
if ( ld->ld_cache == NULLLDCACHE ) {
if (( ld->ld_cache = (LDAPCache *)malloc( sizeof( LDAPCache )))
== NULLLDCACHE ) {
ld->ld_errno = LDAP_NO_MEMORY;
return( -1 );
}
(void) memset( ld->ld_cache, 0, sizeof( LDAPCache ));
ld->ld_cache->lc_memused = sizeof( LDAPCache );
}
ld->ld_cache->lc_timeout = timeout;
ld->ld_cache->lc_maxmem = maxmem;
check_cache_memused( ld->ld_cache );
ld->ld_cache->lc_enabled = 1;
return( 0 );
}
void
ldap_disable_cache( LDAP *ld )
{
if ( ld->ld_cache != NULLLDCACHE ) {
ld->ld_cache->lc_enabled = 0;
}
}
void
ldap_set_cache_options( LDAP *ld, unsigned long opts )
{
if ( ld->ld_cache != NULLLDCACHE ) {
ld->ld_cache->lc_options = opts;
}
}
void
ldap_destroy_cache( LDAP *ld )
{
if ( ld->ld_cache != NULLLDCACHE ) {
ldap_flush_cache( ld );
free( (char *)ld->ld_cache );
ld->ld_cache = NULLLDCACHE;
}
}
void
ldap_flush_cache( LDAP *ld )
{
int i;
LDAPMessage *m, *next;
Debug( LDAP_DEBUG_TRACE, "ldap_flush_cache\n", 0, 0, 0 );
if ( ld->ld_cache != NULLLDCACHE ) {
/* delete all requests in the queue */
for ( m = ld->ld_cache->lc_requests; m != NULLMSG; m = next ) {
next = m->lm_next;
ldap_msgfree( m );
}
ld->ld_cache->lc_requests = NULLMSG;
/* delete all messages in the cache */
for ( i = 0; i < LDAP_CACHE_BUCKETS; ++i ) {
for ( m = ld->ld_cache->lc_buckets[ i ];
m != NULLMSG; m = next ) {
next = m->lm_next;
ldap_msgfree( m );
}
ld->ld_cache->lc_buckets[ i ] = NULLMSG;
}
ld->ld_cache->lc_memused = sizeof( LDAPCache );
}
}
void
ldap_uncache_request( LDAP *ld, int msgid )
{
Debug( LDAP_DEBUG_TRACE, "ldap_uncache_request %d ld_cache %x\n",
msgid, ld->ld_cache, 0 );
uncache_entry_or_req( ld, NULL, msgid );
}
void
ldap_uncache_entry( LDAP *ld, char *dn )
{
Debug( LDAP_DEBUG_TRACE, "ldap_uncache_entry %s ld_cache %x\n",
dn, ld->ld_cache, 0 );
uncache_entry_or_req( ld, dn, 0 );
}
static void
uncache_entry_or_req( LDAP *ld,
char *dn, /* if non-NULL, uncache entry */
int msgid ) /* request to uncache (if dn == NULL) */
{
int i;
LDAPMessage *m, *prev, *next;
Debug( LDAP_DEBUG_TRACE,
"ldap_uncache_entry_or_req dn %s msgid %d ld_cache %x\n",
dn, msgid, ld->ld_cache );
if ( ld->ld_cache == NULLLDCACHE ) {
return;
}
/* first check the request queue */
prev = NULLMSG;
for ( m = ld->ld_cache->lc_requests; m != NULLMSG; m = next ) {
next = m->lm_next;
if (( dn != NULL && chain_contains_dn( m, dn )) ||
( dn == NULL && m->lm_msgid == msgid )) {
if ( prev == NULLMSG ) {
ld->ld_cache->lc_requests = next;
} else {
prev->lm_next = next;
}
ld->ld_cache->lc_memused -= msg_size( m );
ldap_msgfree( m );
} else {
prev = m;
}
}
/* now check the rest of the cache */
for ( i = 0; i < LDAP_CACHE_BUCKETS; ++i ) {
prev = NULLMSG;
for ( m = ld->ld_cache->lc_buckets[ i ]; m != NULLMSG;
m = next ) {
next = m->lm_next;
if (( dn != NULL && chain_contains_dn( m, dn )) ||
( dn == NULL && m->lm_msgid == msgid )) {
if ( prev == NULLMSG ) {
ld->ld_cache->lc_buckets[ i ] = next;
} else {
prev->lm_next = next;
}
ld->ld_cache->lc_memused -= msg_size( m );
ldap_msgfree( m );
} else {
prev = m;
}
}
}
}
void
add_request_to_cache( LDAP *ld, unsigned long msgtype, BerElement *request )
{
LDAPMessage *new;
long len;
Debug( LDAP_DEBUG_TRACE, "add_request_to_cache\n", 0, 0, 0 );
ld->ld_errno = LDAP_SUCCESS;
if ( ld->ld_cache == NULLLDCACHE ||
( ld->ld_cache->lc_enabled == 0 )) {
return;
}
if (( new = (LDAPMessage *) calloc( 1, sizeof(LDAPMessage) ))
!= NULL ) {
if (( new->lm_ber = alloc_ber_with_options( ld )) == NULLBER ) {
free( (char *)new );
return;
}
len = request->ber_ptr - request->ber_buf;
if (( new->lm_ber->ber_buf = (char *) malloc( (size_t)len ))
== NULL ) {
ber_free( new->lm_ber, 0 );
free( (char *)new );
ld->ld_errno = LDAP_NO_MEMORY;
return;
}
SAFEMEMCPY( new->lm_ber->ber_buf, request->ber_buf,
(size_t)len );
new->lm_ber->ber_ptr = new->lm_ber->ber_buf;
new->lm_ber->ber_end = new->lm_ber->ber_buf + len;
new->lm_msgid = ld->ld_msgid;
new->lm_msgtype = msgtype;;
new->lm_next = ld->ld_cache->lc_requests;
ld->ld_cache->lc_requests = new;
} else {
ld->ld_errno = LDAP_NO_MEMORY;
}
}
void
add_result_to_cache( LDAP *ld, LDAPMessage *result )
{
LDAPMessage *m, **mp, *req, *new, *prev;
int err, keep;
Debug( LDAP_DEBUG_TRACE, "add_result_to_cache: id %d, type %d\n",
result->lm_msgid, result->lm_msgtype, 0 );
if ( ld->ld_cache == NULLLDCACHE ||
( ld->ld_cache->lc_enabled == 0 )) {
Debug( LDAP_DEBUG_TRACE, "artc: cache disabled\n", 0, 0, 0 );
return;
}
if ( result->lm_msgtype != LDAP_RES_SEARCH_ENTRY &&
result->lm_msgtype != LDAP_RES_SEARCH_RESULT &&
result->lm_msgtype != LDAP_RES_COMPARE ) {
/*
* only cache search and compare operations
*/
Debug( LDAP_DEBUG_TRACE,
"artc: only caching search & compare operations\n", 0, 0, 0 );
return;
}
/*
* if corresponding request is in the lc_requests list, add this
* result to it. if this result completes the results for the
* request, add the request/result chain to the cache proper.
*/
prev = NULLMSG;
for ( m = ld->ld_cache->lc_requests; m != NULL; m = m->lm_next ) {
if ( m->lm_msgid == result->lm_msgid ) {
break;
}
prev = m;
}
if ( m != NULLMSG ) { /* found request; add to end of chain */
req = m;
for ( ; m->lm_chain != NULLMSG; m = m->lm_chain )
;
if (( new = msg_dup( result )) != NULLMSG ) {
new->lm_chain = NULLMSG;
m->lm_chain = new;
Debug( LDAP_DEBUG_TRACE,
"artc: result added to cache request chain\n",
0, 0, 0 );
}
if ( result->lm_msgtype == LDAP_RES_SEARCH_RESULT ||
result->lm_msgtype == LDAP_RES_COMPARE ) {
/*
* this result completes the chain of results
* add to cache proper if appropriate
*/
keep = 0; /* pessimistic */
err = ldap_result2error( ld, result, 0 );
if ( err == LDAP_SUCCESS ||
( result->lm_msgtype == LDAP_RES_COMPARE &&
( err == LDAP_COMPARE_FALSE ||
err == LDAP_COMPARE_TRUE ||
err == LDAP_NO_SUCH_ATTRIBUTE ))) {
keep = 1;
}
if ( ld->ld_cache->lc_options == 0 ) {
if ( err == LDAP_SIZELIMIT_EXCEEDED ) {
keep = 1;
}
} else if (( ld->ld_cache->lc_options &
LDAP_CACHE_OPT_CACHEALLERRS ) != 0 ) {
keep = 1;
}
if ( prev == NULLMSG ) {
ld->ld_cache->lc_requests = req->lm_next;
} else {
prev->lm_next = req->lm_next;
}
if ( !keep ) {
Debug( LDAP_DEBUG_TRACE,
"artc: not caching result with error %d\n",
err, 0, 0 );
ldap_msgfree( req );
} else {
mp = &ld->ld_cache->lc_buckets[
cache_hash( req->lm_ber ) ];
req->lm_next = *mp;
*mp = req;
req->lm_time = (long) time( NULL );
ld->ld_cache->lc_memused += msg_size( req );
check_cache_memused( ld->ld_cache );
Debug( LDAP_DEBUG_TRACE,
"artc: cached result with error %d\n",
err, 0, 0 );
}
}
} else {
Debug( LDAP_DEBUG_TRACE, "artc: msgid not in request list\n",
0, 0, 0 );
}
}
/*
* look in the cache for this request
* return 0 if found, -1 if not
* if found, the corresponding result messages are added to the incoming
* queue with the correct (new) msgid so that subsequent ldap_result calls
* will find them.
*/
int
check_cache( LDAP *ld, unsigned long msgtype, BerElement *request )
{
LDAPMessage *m, *new, *prev, *next;
BerElement reqber;
int first, hash;
unsigned long validtime;
Debug( LDAP_DEBUG_TRACE, "check_cache\n", 0, 0, 0 );
if ( ld->ld_cache == NULLLDCACHE ||
( ld->ld_cache->lc_enabled == 0 )) {
return( -1 );
}
reqber.ber_buf = reqber.ber_ptr = request->ber_buf;
reqber.ber_end = request->ber_ptr;
validtime = (long)time( NULL ) - ld->ld_cache->lc_timeout;
prev = NULLMSG;
hash = cache_hash( &reqber );
for ( m = ld->ld_cache->lc_buckets[ hash ]; m != NULLMSG; m = next ) {
Debug( LDAP_DEBUG_TRACE,"cc: examining id %d,type %d\n",
m->lm_msgid, m->lm_msgtype, 0 );
if ( m->lm_time < validtime ) {
/* delete expired message */
next = m->lm_next;
if ( prev == NULL ) {
ld->ld_cache->lc_buckets[ hash ] = next;
} else {
prev->lm_next = next;
}
Debug( LDAP_DEBUG_TRACE, "cc: expired id %d\n",
m->lm_msgid, 0, 0 );
ld->ld_cache->lc_memused -= msg_size( m );
ldap_msgfree( m );
} else {
if ( m->lm_msgtype == (int)msgtype &&
request_cmp( m->lm_ber, &reqber ) == 0 ) {
break;
}
next = m->lm_next;
prev = m;
}
}
if ( m == NULLMSG ) {
return( -1 );
}
/*
* add duplicates of responses to incoming queue
*/
first = 1;
for ( m = m->lm_chain; m != NULLMSG; m = m->lm_chain ) {
if (( new = msg_dup( m )) == NULLMSG ) {
return( -1 );
}
new->lm_msgid = ld->ld_msgid;
new->lm_chain = NULLMSG;
if ( first ) {
new->lm_next = ld->ld_responses;
ld->ld_responses = new;
first = 0;
} else {
prev->lm_chain = new;
}
prev = new;
Debug( LDAP_DEBUG_TRACE, "cc: added type %d\n",
new->lm_msgtype, 0, 0 );
}
Debug( LDAP_DEBUG_TRACE, "cc: result returned from cache\n", 0, 0, 0 );
return( 0 );
}
static int
cache_hash( BerElement *ber )
{
BerElement bercpy;
unsigned long len;
/*
* just take the length of the packet and mod with # of buckets
*/
bercpy = *ber;
if ( ber_skip_tag( &bercpy, &len ) == LBER_ERROR
|| ber_scanf( &bercpy, "x" ) == LBER_ERROR ) {
len = 0; /* punt: just return zero */
} else {
len = bercpy.ber_end - bercpy.ber_ptr;
}
Debug( LDAP_DEBUG_TRACE, "cache_hash: len is %ld, returning %ld\n",
len, len % LDAP_CACHE_BUCKETS, 0 );
return( (int) ( len % LDAP_CACHE_BUCKETS ));
}
static LDAPMessage *
msg_dup( LDAPMessage *msg )
{
LDAPMessage *new;
long len;
if (( new = (LDAPMessage *)malloc( sizeof(LDAPMessage))) != NULL ) {
*new = *msg; /* struct copy */
if (( new->lm_ber = ber_dup( msg->lm_ber )) == NULLBER ) {
free( (char *)new );
return( NULLMSG );
}
len = msg->lm_ber->ber_end - msg->lm_ber->ber_buf;
if (( new->lm_ber->ber_buf = (char *) malloc(
(size_t)len )) == NULL ) {
ber_free( new->lm_ber, 0 );
free( (char *)new );
return( NULLMSG );
}
SAFEMEMCPY( new->lm_ber->ber_buf, msg->lm_ber->ber_buf,
(size_t)len );
new->lm_ber->ber_ptr = new->lm_ber->ber_buf +
( msg->lm_ber->ber_ptr - msg->lm_ber->ber_buf );
new->lm_ber->ber_end = new->lm_ber->ber_buf + len;
}
return( new );
}
static int
request_cmp( BerElement *req1, BerElement *req2 )
{
unsigned long len;
BerElement r1, r2;
r1 = *req1; /* struct copies */
r2 = *req2;
/*
* skip the enclosing tags (sequence markers) and the msg ids
*/
if ( ber_skip_tag( &r1, &len ) == LBER_ERROR || ber_scanf( &r1, "x" )
== LBER_ERROR ) {
return( -1 );
}
if ( ber_skip_tag( &r2, &len ) == LBER_ERROR || ber_scanf( &r2, "x" )
== LBER_ERROR ) {
return( -1 );
}
/*
* check remaining length and bytes if necessary
*/
if (( len = r1.ber_end - r1.ber_ptr ) != r2.ber_end - r2.ber_ptr ) {
return( -1 ); /* different lengths */
}
return( memcmp( r1.ber_ptr, r2.ber_ptr, (size_t)len ));
}
static int
chain_contains_dn( LDAPMessage *msg, char *dn )
{
LDAPMessage *m;
BerElement ber;
long msgid;
char *s;
int rc;
/*
* first check the base or dn of the request
*/
ber = *msg->lm_ber; /* struct copy */
if ( ber_scanf( &ber, "{i{a", &msgid, &s ) != LBER_ERROR ) {
rc = ( strcasecmp( dn, s ) == 0 ) ? 1 : 0;
free( s );
if ( rc != 0 ) {
return( rc );
}
}
if ( msg->lm_msgtype == LDAP_REQ_COMPARE ) {
return( 0 );
}
/*
* now check the dn of each search result
*/
rc = 0;
for ( m = msg->lm_chain; m != NULLMSG && rc == 0 ; m = m->lm_chain ) {
if ( m->lm_msgtype != LDAP_RES_SEARCH_ENTRY ) {
continue;
}
ber = *m->lm_ber; /* struct copy */
if ( ber_scanf( &ber, "{a", &s ) != LBER_ERROR ) {
rc = ( strcasecmp( dn, s ) == 0 ) ? 1 : 0;
free( s );
}
}
return( rc );
}
static long
msg_size( LDAPMessage *msg )
{
LDAPMessage *m;
long size;
size = 0;
for ( m = msg; m != NULLMSG; m = m->lm_chain ) {
size += ( sizeof( LDAPMessage ) + m->lm_ber->ber_end -
m->lm_ber->ber_buf );
}
return( size );
}
#define THRESHOLD_FACTOR 3 / 4
#define SIZE_FACTOR 2 / 3
static void
check_cache_memused( LDAPCache *lc )
{
/*
* this routine is called to check if the cache is too big (lc_maxmem >
* minimum cache size and lc_memused > lc_maxmem). If too big, it reduces
* the cache size to < SIZE_FACTOR * lc_maxmem. The algorithm is as follows:
* remove_threshold = lc_timeout seconds;
* do {
* remove everything older than remove_threshold seconds;
* remove_threshold = remove_threshold * THRESHOLD_FACTOR;
* } while ( cache size is > SIZE_FACTOR * lc_maxmem )
*/
int i;
unsigned long remove_threshold, validtime;
LDAPMessage *m, *prev, *next;
Debug( LDAP_DEBUG_TRACE, "check_cache_memused: %ld bytes in use (%ld max)\n",
lc->lc_memused, lc->lc_maxmem, 0 );
if ( lc->lc_maxmem <= sizeof( LDAPCache )
|| lc->lc_memused <= lc->lc_maxmem * SIZE_FACTOR ) {
return;
}
remove_threshold = lc->lc_timeout;
while ( lc->lc_memused > lc->lc_maxmem * SIZE_FACTOR ) {
validtime = (long)time( NULL ) - remove_threshold;
for ( i = 0; i < LDAP_CACHE_BUCKETS; ++i ) {
prev = NULLMSG;
for ( m = lc->lc_buckets[ i ]; m != NULLMSG;
m = next ) {
next = m->lm_next;
if ( m->lm_time < validtime ) {
if ( prev == NULLMSG ) {
lc->lc_buckets[ i ] = next;
} else {
prev->lm_next = next;
}
lc->lc_memused -= msg_size( m );
Debug( LDAP_DEBUG_TRACE,
"ccm: removed %d\n",
m->lm_msgid, 0, 0 );
ldap_msgfree( m );
} else {
prev = m;
}
}
}
remove_threshold *= THRESHOLD_FACTOR;
}
Debug( LDAP_DEBUG_TRACE, "ccm: reduced usage to %ld bytes\n",
lc->lc_memused, 0, 0 );
}
#endif /* !NO_CACHE */