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/*++
/* NAME
/* scache_multi 3
/* SUMMARY
/* multi-session cache
/* SYNOPSIS
/* #include <scache.h>
/* DESCRIPTION
/* SCACHE *scache_multi_create()
/* DESCRIPTION
/* This module implements an in-memory, multi-session cache.
/*
/* scache_multi_create() instantiates a session cache that
/* stores multiple sessions.
/* DIAGNOSTICS
/* Fatal error: memory allocation problem;
/* panic: internal consistency failure.
/* SEE ALSO
/* scache(3), generic session cache API
/* LICENSE
/* .ad
/* .fi
/* The Secure Mailer license must be distributed with this software.
/* AUTHOR(S)
/* Wietse Venema
/* IBM T.J. Watson Research
/* P.O. Box 704
/* Yorktown Heights, NY 10598, USA
/*--*/
/* System library. */
#include <sys_defs.h>
#include <unistd.h>
#include <stddef.h> /* offsetof() */
#include <string.h>
/* Utility library. */
#include <msg.h>
#include <ring.h>
#include <htable.h>
#include <vstring.h>
#include <mymalloc.h>
#include <events.h>
/*#define msg_verbose 1*/
/* Global library. */
#include <scache.h>
/* Application-specific. */
/*
* SCACHE_MULTI is a derived type from the SCACHE super-class.
*
* Each destination has an entry in the destination hash table, and each
* destination->endpoint binding is kept in a circular list under its
* destination hash table entry.
*
* Likewise, each endpoint has an entry in the endpoint hash table, and each
* endpoint->session binding is kept in a circular list under its endpoint
* hash table entry.
*
* We do not attempt to limit the number of destination or endpoint entries,
* nor do we attempt to limit the number of sessions. Doing so would require
* a write-through cache. Currently, the CTABLE cache module supports only
* read-through caching.
*
* This is no problem because the number of cached destinations is limited by
* design. Sites that specify a wild-card domain pattern, and thus cache
* every session in recent history, may be in for a surprise.
*/
typedef struct {
SCACHE scache[1]; /* super-class */
HTABLE *dest_cache; /* destination->endpoint bindings */
HTABLE *endp_cache; /* endpoint->session bindings */
int sess_count; /* number of cached sessions */
} SCACHE_MULTI;
/*
* Storage for a destination or endpoint list head. Each list head knows its
* own hash table entry name, so that we can remove the list when it becomes
* empty. List items are stored in a circular list under the list head.
*/
typedef struct {
RING ring[1]; /* circular list linkage */
char *parent_key; /* parent linkage: hash table */
SCACHE_MULTI *cache; /* parent linkage: cache */
} SCACHE_MULTI_HEAD;
#define RING_TO_MULTI_HEAD(p) RING_TO_APPL((p), SCACHE_MULTI_HEAD, ring)
/*
* Storage for a destination->endpoint binding. This is an element in a
* circular list, whose list head specifies the destination.
*/
typedef struct {
RING ring[1]; /* circular list linkage */
SCACHE_MULTI_HEAD *head; /* parent linkage: list head */
char *endp_label; /* endpoint name */
char *dest_prop; /* binding properties */
} SCACHE_MULTI_DEST;
#define RING_TO_MULTI_DEST(p) RING_TO_APPL((p), SCACHE_MULTI_DEST, ring)
static void scache_multi_expire_dest(int, void *);
/*
* Storage for an endpoint->session binding. This is an element in a
* circular list, whose list head specifies the endpoint.
*/
typedef struct {
RING ring[1]; /* circular list linkage */
SCACHE_MULTI_HEAD *head; /* parent linkage: list head */
int fd; /* cached session */
char *endp_prop; /* binding properties */
} SCACHE_MULTI_ENDP;
#define RING_TO_MULTI_ENDP(p) RING_TO_APPL((p), SCACHE_MULTI_ENDP, ring)
static void scache_multi_expire_endp(int, void *);
/*
* When deleting a circular list element, are we deleting the entire
* circular list, or are we removing a single list element. We need this
* distinction to avoid a re-entrancy problem between htable_delete() and
* htable_free().
*/
#define BOTTOM_UP 1 /* one item */
#define TOP_DOWN 2 /* whole list */
/* scache_multi_drop_endp - destroy endpoint->session binding */
static void scache_multi_drop_endp(SCACHE_MULTI_ENDP *endp, int direction)
{
const char *myname = "scache_multi_drop_endp";
SCACHE_MULTI_HEAD *head;
if (msg_verbose)
msg_info("%s: endp_prop=%s fd=%d", myname,
endp->endp_prop, endp->fd);
/*
* Stop the timer.
*/
event_cancel_timer(scache_multi_expire_endp, (void *) endp);
/*
* In bottom-up mode, remove the list head from the endpoint hash when
* the list becomes empty. Otherwise, remove the endpoint->session
* binding from the list.
*/
ring_detach(endp->ring);
head = endp->head;
head->cache->sess_count--;
if (direction == BOTTOM_UP && ring_pred(head->ring) == head->ring)
htable_delete(head->cache->endp_cache, head->parent_key, myfree);
/*
* Destroy the endpoint->session binding.
*/
if (endp->fd >= 0 && close(endp->fd) != 0)
msg_warn("%s: close(%d): %m", myname, endp->fd);
myfree(endp->endp_prop);
myfree((void *) endp);
}
/* scache_multi_expire_endp - event timer call-back */
static void scache_multi_expire_endp(int unused_event, void *context)
{
SCACHE_MULTI_ENDP *endp = (SCACHE_MULTI_ENDP *) context;
scache_multi_drop_endp(endp, BOTTOM_UP);
}
/* scache_multi_free_endp - hash table destructor call-back */
static void scache_multi_free_endp(void *ptr)
{
SCACHE_MULTI_HEAD *head = (SCACHE_MULTI_HEAD *) ptr;
SCACHE_MULTI_ENDP *endp;
RING *ring;
/*
* Delete each endpoint->session binding in the list, then delete the
* list head. Note: this changes the list, so we must iterate carefully.
*/
while ((ring = ring_succ(head->ring)) != head->ring) {
endp = RING_TO_MULTI_ENDP(ring);
scache_multi_drop_endp(endp, TOP_DOWN);
}
myfree((void *) head);
}
/* scache_multi_save_endp - save endpoint->session binding */
static void scache_multi_save_endp(SCACHE *scache, int ttl,
const char *endp_label,
const char *endp_prop, int fd)
{
const char *myname = "scache_multi_save_endp";
SCACHE_MULTI *sp = (SCACHE_MULTI *) scache;
SCACHE_MULTI_HEAD *head;
SCACHE_MULTI_ENDP *endp;
if (ttl < 0)
msg_panic("%s: bad ttl: %d", myname, ttl);
/*
* Look up or instantiate the list head with the endpoint name.
*/
if ((head = (SCACHE_MULTI_HEAD *)
htable_find(sp->endp_cache, endp_label)) == 0) {
head = (SCACHE_MULTI_HEAD *) mymalloc(sizeof(*head));
ring_init(head->ring);
head->parent_key =
htable_enter(sp->endp_cache, endp_label, (void *) head)->key;
head->cache = sp;
}
/*
* Add the endpoint->session binding to the list. There can never be a
* duplicate, because each session must have a different file descriptor.
*/
endp = (SCACHE_MULTI_ENDP *) mymalloc(sizeof(*endp));
endp->head = head;
endp->fd = fd;
endp->endp_prop = mystrdup(endp_prop);
ring_prepend(head->ring, endp->ring);
sp->sess_count++;
/*
* Make sure this binding will go away eventually.
*/
event_request_timer(scache_multi_expire_endp, (void *) endp, ttl);
if (msg_verbose)
msg_info("%s: endp_label=%s -> endp_prop=%s fd=%d",
myname, endp_label, endp_prop, fd);
}
/* scache_multi_find_endp - look up session for named endpoint */
static int scache_multi_find_endp(SCACHE *scache, const char *endp_label,
VSTRING *endp_prop)
{
const char *myname = "scache_multi_find_endp";
SCACHE_MULTI *sp = (SCACHE_MULTI *) scache;
SCACHE_MULTI_HEAD *head;
SCACHE_MULTI_ENDP *endp;
RING *ring;
int fd;
/*
* Look up the list head with the endpoint name.
*/
if ((head = (SCACHE_MULTI_HEAD *)
htable_find(sp->endp_cache, endp_label)) == 0) {
if (msg_verbose)
msg_info("%s: no endpoint cache: endp_label=%s",
myname, endp_label);
return (-1);
}
/*
* Use the first available session. Remove the session from the cache
* because we're giving it to someone else.
*/
if ((ring = ring_succ(head->ring)) != head->ring) {
endp = RING_TO_MULTI_ENDP(ring);
fd = endp->fd;
endp->fd = -1;
vstring_strcpy(endp_prop, endp->endp_prop);
if (msg_verbose)
msg_info("%s: found: endp_label=%s -> endp_prop=%s fd=%d",
myname, endp_label, endp->endp_prop, fd);
scache_multi_drop_endp(endp, BOTTOM_UP);
return (fd);
}
if (msg_verbose)
msg_info("%s: not found: endp_label=%s", myname, endp_label);
return (-1);
}
/* scache_multi_drop_dest - delete destination->endpoint binding */
static void scache_multi_drop_dest(SCACHE_MULTI_DEST *dest, int direction)
{
const char *myname = "scache_multi_drop_dest";
SCACHE_MULTI_HEAD *head;
if (msg_verbose)
msg_info("%s: dest_prop=%s endp_label=%s",
myname, dest->dest_prop, dest->endp_label);
/*
* Stop the timer.
*/
event_cancel_timer(scache_multi_expire_dest, (void *) dest);
/*
* In bottom-up mode, remove the list head from the destination hash when
* the list becomes empty. Otherwise, remove the destination->endpoint
* binding from the list.
*/
ring_detach(dest->ring);
head = dest->head;
if (direction == BOTTOM_UP && ring_pred(head->ring) == head->ring)
htable_delete(head->cache->dest_cache, head->parent_key, myfree);
/*
* Destroy the destination->endpoint binding.
*/
myfree(dest->dest_prop);
myfree(dest->endp_label);
myfree((void *) dest);
}
/* scache_multi_expire_dest - event timer call-back */
static void scache_multi_expire_dest(int unused_event, void *context)
{
SCACHE_MULTI_DEST *dest = (SCACHE_MULTI_DEST *) context;
scache_multi_drop_dest(dest, BOTTOM_UP);
}
/* scache_multi_free_dest - hash table destructor call-back */
static void scache_multi_free_dest(void *ptr)
{
SCACHE_MULTI_HEAD *head = (SCACHE_MULTI_HEAD *) ptr;
SCACHE_MULTI_DEST *dest;
RING *ring;
/*
* Delete each destination->endpoint binding in the list, then delete the
* list head. Note: this changes the list, so we must iterate carefully.
*/
while ((ring = ring_succ(head->ring)) != head->ring) {
dest = RING_TO_MULTI_DEST(ring);
scache_multi_drop_dest(dest, TOP_DOWN);
}
myfree((void *) head);
}
/* scache_multi_save_dest - save destination->endpoint binding */
static void scache_multi_save_dest(SCACHE *scache, int ttl,
const char *dest_label,
const char *dest_prop,
const char *endp_label)
{
const char *myname = "scache_multi_save_dest";
SCACHE_MULTI *sp = (SCACHE_MULTI *) scache;
SCACHE_MULTI_HEAD *head;
SCACHE_MULTI_DEST *dest;
RING *ring;
int refresh = 0;
if (ttl < 0)
msg_panic("%s: bad ttl: %d", myname, ttl);
/*
* Look up or instantiate the list head with the destination name.
*/
if ((head = (SCACHE_MULTI_HEAD *)
htable_find(sp->dest_cache, dest_label)) == 0) {
head = (SCACHE_MULTI_HEAD *) mymalloc(sizeof(*head));
ring_init(head->ring);
head->parent_key =
htable_enter(sp->dest_cache, dest_label, (void *) head)->key;
head->cache = sp;
}
/*
* Look up or instantiate the destination->endpoint binding. Update the
* expiration time if this destination->endpoint binding already exists.
*/
RING_FOREACH(ring, head->ring) {
dest = RING_TO_MULTI_DEST(ring);
if (strcmp(dest->endp_label, endp_label) == 0
&& strcmp(dest->dest_prop, dest_prop) == 0) {
refresh = 1;
break;
}
}
if (refresh == 0) {
dest = (SCACHE_MULTI_DEST *) mymalloc(sizeof(*dest));
dest->head = head;
dest->endp_label = mystrdup(endp_label);
dest->dest_prop = mystrdup(dest_prop);
ring_prepend(head->ring, dest->ring);
}
/*
* Make sure this binding will go away eventually.
*/
event_request_timer(scache_multi_expire_dest, (void *) dest, ttl);
if (msg_verbose)
msg_info("%s: dest_label=%s -> dest_prop=%s endp_label=%s%s",
myname, dest_label, dest_prop, endp_label,
refresh ? " (refreshed)" : "");
}
/* scache_multi_find_dest - look up session for named destination */
static int scache_multi_find_dest(SCACHE *scache, const char *dest_label,
VSTRING *dest_prop,
VSTRING *endp_prop)
{
const char *myname = "scache_multi_find_dest";
SCACHE_MULTI *sp = (SCACHE_MULTI *) scache;
SCACHE_MULTI_HEAD *head;
SCACHE_MULTI_DEST *dest;
RING *ring;
int fd;
/*
* Look up the list head with the destination name.
*/
if ((head = (SCACHE_MULTI_HEAD *)
htable_find(sp->dest_cache, dest_label)) == 0) {
if (msg_verbose)
msg_info("%s: no destination cache: dest_label=%s",
myname, dest_label);
return (-1);
}
/*
* Search endpoints for the first available session.
*/
RING_FOREACH(ring, head->ring) {
dest = RING_TO_MULTI_DEST(ring);
fd = scache_multi_find_endp(scache, dest->endp_label, endp_prop);
if (fd >= 0) {
vstring_strcpy(dest_prop, dest->dest_prop);
return (fd);
}
}
if (msg_verbose)
msg_info("%s: not found: dest_label=%s", myname, dest_label);
return (-1);
}
/* scache_multi_size - size of multi-element cache object */
static void scache_multi_size(SCACHE *scache, SCACHE_SIZE *size)
{
SCACHE_MULTI *sp = (SCACHE_MULTI *) scache;
size->dest_count = sp->dest_cache->used;
size->endp_count = sp->endp_cache->used;
size->sess_count = sp->sess_count;
}
/* scache_multi_free - destroy multi-element cache object */
static void scache_multi_free(SCACHE *scache)
{
SCACHE_MULTI *sp = (SCACHE_MULTI *) scache;
htable_free(sp->dest_cache, scache_multi_free_dest);
htable_free(sp->endp_cache, scache_multi_free_endp);
myfree((void *) sp);
}
/* scache_multi_create - initialize */
SCACHE *scache_multi_create(void)
{
SCACHE_MULTI *sp = (SCACHE_MULTI *) mymalloc(sizeof(*sp));
sp->scache->save_endp = scache_multi_save_endp;
sp->scache->find_endp = scache_multi_find_endp;
sp->scache->save_dest = scache_multi_save_dest;
sp->scache->find_dest = scache_multi_find_dest;
sp->scache->size = scache_multi_size;
sp->scache->free = scache_multi_free;
sp->dest_cache = htable_create(1);
sp->endp_cache = htable_create(1);
sp->sess_count = 0;
return (sp->scache);
}