cache_req_search.c revision 8bb6680637ead03e24a38d15ec5265d11a920a1d
/*
Authors:
Pavel Březina <pbrezina@redhat.com>
Copyright (C) 2016 Red Hat
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 3 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, see <http://www.gnu.org/licenses/>.
*/
#include <ldb.h>
#include <talloc.h>
#include <tevent.h>
#include "util/util.h"
#include "responder/common/cache_req/cache_req_private.h"
#include "responder/common/cache_req/cache_req_plugin.h"
static errno_t cache_req_search_ncache(struct cache_req *cr)
{
errno_t ret;
if (cr->plugin->ncache_check_fn == NULL) {
CACHE_REQ_DEBUG(SSSDBG_TRACE_INTERNAL, cr,
"This request type does not support negative cache\n");
return EOK;
}
CACHE_REQ_DEBUG(SSSDBG_TRACE_FUNC, cr,
"Checking negative cache for [%s]\n",
cr->debugobj);
ret = cr->plugin->ncache_check_fn(cr->ncache, cr->domain, cr->data);
if (ret == EEXIST) {
CACHE_REQ_DEBUG(SSSDBG_TRACE_FUNC, cr,
"[%s] does not exist (negative cache)\n",
cr->debugobj);
return ENOENT;
} else if (ret != EOK && ret != ENOENT) {
CACHE_REQ_DEBUG(SSSDBG_CRIT_FAILURE, cr,
"Unable to check negative cache [%d]: %s\n",
ret, sss_strerror(ret));
return ret;
}
CACHE_REQ_DEBUG(SSSDBG_TRACE_FUNC, cr,
"[%s] is not present in negative cache\n",
cr->debugobj);
return EOK;
}
static void cache_req_search_ncache_add(struct cache_req *cr)
{
errno_t ret;
if (cr->plugin->ncache_add_fn == NULL) {
CACHE_REQ_DEBUG(SSSDBG_TRACE_INTERNAL, cr,
"This request type does not support negative cache\n");
return;
}
CACHE_REQ_DEBUG(SSSDBG_TRACE_FUNC, cr, "Adding [%s] to negative cache\n",
cr->debugobj);
ret = cr->plugin->ncache_add_fn(cr->ncache, cr->domain, cr->data);
if (ret != EOK) {
CACHE_REQ_DEBUG(SSSDBG_MINOR_FAILURE, cr,
"Cannot set negative cache for [%s] [%d]: %s\n",
cr->debugobj, ret, sss_strerror(ret));
/* not fatal */
}
return;
}
static errno_t cache_req_search_cache(TALLOC_CTX *mem_ctx,
struct cache_req *cr,
struct ldb_result **_result)
{
struct ldb_result *result = NULL;
errno_t ret;
if (cr->plugin->lookup_fn == NULL) {
CACHE_REQ_DEBUG(SSSDBG_CRIT_FAILURE, cr,
"Bug: No cache lookup function specified\n");
return ERR_INTERNAL;
}
CACHE_REQ_DEBUG(SSSDBG_TRACE_FUNC, cr,
"Looking up [%s] in cache\n",
cr->debugobj);
ret = cr->plugin->lookup_fn(mem_ctx, cr, cr->data, cr->domain, &result);
if (ret == EOK && (result == NULL || result->count == 0)) {
ret = ENOENT;
}
switch (ret) {
case EOK:
if (cr->plugin->only_one_result && result->count > 1) {
CACHE_REQ_DEBUG(SSSDBG_CRIT_FAILURE, cr,
"Multiple objects were found when "
"only one was expected!\n");
ret = ERR_INTERNAL;
goto done;
}
*_result = result;
break;
case ENOENT:
CACHE_REQ_DEBUG(SSSDBG_TRACE_FUNC, cr,
"Object [%s] was not found in cache\n",
cr->debugobj);
break;
default:
CACHE_REQ_DEBUG(SSSDBG_CRIT_FAILURE, cr,
"Unable to lookup [%s] in cache [%d]: %s\n",
cr->debugobj, ret, sss_strerror(ret));
break;
}
done:
if (ret != EOK) {
talloc_free(result);
}
return ret;
}
static enum cache_object_status
cache_req_expiration_status(struct cache_req *cr,
struct ldb_result *result)
{
time_t expire;
errno_t ret;
if (result == NULL || result->count == 0 || cr->plugin->bypass_cache) {
return CACHE_OBJECT_MISSING;
}
expire = ldb_msg_find_attr_as_uint64(result->msgs[0],
cr->plugin->attr_expiration, 0);
ret = sss_cmd_check_cache(result->msgs[0], cr->midpoint, expire);
if (ret == EOK) {
return CACHE_OBJECT_VALID;
} else if (ret == EAGAIN) {
return CACHE_OBJECT_MIDPOINT;
}
return CACHE_OBJECT_EXPIRED;
}
struct cache_req_search_state {
/* input data */
struct tevent_context *ev;
struct resp_ctx *rctx;
struct cache_req *cr;
/* output data */
struct ldb_result *result;
bool dp_success;
};
static errno_t cache_req_search_dp(struct tevent_req *req,
enum cache_object_status status);
static void cache_req_search_oob_done(struct tevent_req *subreq);
static void cache_req_search_done(struct tevent_req *subreq);
struct tevent_req *
cache_req_search_send(TALLOC_CTX *mem_ctx,
struct tevent_context *ev,
struct cache_req *cr,
bool bypass_cache,
bool bypass_dp)
{
struct cache_req_search_state *state;
enum cache_object_status status;
struct tevent_req *req;
errno_t ret;
req = tevent_req_create(mem_ctx, &state, struct cache_req_search_state);
if (req == NULL) {
DEBUG(SSSDBG_CRIT_FAILURE, "tevent_req_create() failed\n");
return NULL;
}
CACHE_REQ_DEBUG(SSSDBG_TRACE_FUNC, cr, "Looking up %s\n", cr->debugobj);
state->ev = ev;
state->cr = cr;
ret = cache_req_search_ncache(cr);
if (ret != EOK) {
goto done;
}
/* If bypass_cache is enabled we always contact data provider before
* searching the cache. Thus we set expiration status to missing,
* which will trigger data provider request later.
*
* If disabled, we want to search the cache here to see if the
* object is already cached and valid or if data provider needs
* to be contacted.
*/
state->result = NULL;
status = CACHE_OBJECT_MISSING;
if (!bypass_cache) {
ret = cache_req_search_cache(state, cr, &state->result);
if (ret != EOK && ret != ENOENT) {
goto done;
}
status = cache_req_expiration_status(cr, state->result);
if (status == CACHE_OBJECT_VALID) {
CACHE_REQ_DEBUG(SSSDBG_TRACE_FUNC, cr,
"Returning [%s] from cache\n", cr->debugobj);
ret = EOK;
goto done;
}
}
if (!bypass_dp) {
ret = cache_req_search_dp(req, status);
}
if (ret != EAGAIN) {
goto done;
}
return req;
done:
if (ret == EOK) {
tevent_req_done(req);
} else {
tevent_req_error(req, ret);
}
tevent_req_post(req, ev);
return req;
}
static errno_t cache_req_search_dp(struct tevent_req *req,
enum cache_object_status status)
{
struct cache_req_search_state *state;
struct tevent_req *subreq;
errno_t ret;
state = tevent_req_data(req, struct cache_req_search_state);
switch (status) {
case CACHE_OBJECT_MIDPOINT:
/* Out of band update. The calling function will return the cached
* entry immediately. We need to use rctx so the request is not
* removed when state is freed. */
CACHE_REQ_DEBUG(SSSDBG_TRACE_FUNC, state->cr,
"Performing midpoint cache update of [%s]\n",
state->cr->debugobj);
subreq = state->cr->plugin->dp_send_fn(state->rctx, state->cr,
state->cr->data,
state->cr->domain,
state->result);
if (subreq == NULL) {
DEBUG(SSSDBG_CRIT_FAILURE, "Out of memory sending out-of-band "
"data provider request\n");
/* This is non-fatal, so we'll continue here */
} else {
tevent_req_set_callback(subreq, cache_req_search_oob_done, req);
}
ret = EOK;
break;
case CACHE_OBJECT_EXPIRED:
case CACHE_OBJECT_MISSING:
CACHE_REQ_DEBUG(SSSDBG_TRACE_FUNC, state->cr,
"Looking up [%s] in data provider\n",
state->cr->debugobj);
subreq = state->cr->plugin->dp_send_fn(state->cr, state->cr,
state->cr->data,
state->cr->domain,
state->result);
if (subreq == NULL) {
DEBUG(SSSDBG_CRIT_FAILURE,
"Out of memory sending data provider request\n");
ret = ENOMEM;
break;
}
tevent_req_set_callback(subreq, cache_req_search_done, req);
ret = EAGAIN;
break;
default:
/* error */
CACHE_REQ_DEBUG(SSSDBG_CRIT_FAILURE, state->cr,
"Unexpected status [%d]\n", status);
ret = ERR_INTERNAL;
break;
}
return ret;
}
static void cache_req_search_oob_done(struct tevent_req *subreq)
{
DEBUG(SSSDBG_TRACE_INTERNAL, "Out of band request finished\n");
talloc_zfree(subreq);
return;
}
static void cache_req_search_done(struct tevent_req *subreq)
{
struct cache_req_search_state *state;
struct tevent_req *req;
errno_t ret;
req = tevent_req_callback_data(subreq, struct tevent_req);
state = tevent_req_data(req, struct cache_req_search_state);
state->dp_success = state->cr->plugin->dp_recv_fn(subreq, state->cr);
talloc_zfree(subreq);
/* Get result from cache again. */
ret = cache_req_search_cache(state, state->cr, &state->result);
if (ret == ENOENT) {
/* Only store entry in negative cache if DP request succeeded
* because only then we know that the entry does not exist. */
if (state->dp_success) {
cache_req_search_ncache_add(state->cr);
}
tevent_req_error(req, ENOENT);
return;
} else if (ret != EOK) {
tevent_req_error(req, ret);
return;
}
CACHE_REQ_DEBUG(SSSDBG_TRACE_FUNC, state->cr,
"Returning updated object [%s]\n", state->cr->debugobj);
tevent_req_done(req);
return;
}
errno_t cache_req_search_recv(TALLOC_CTX *mem_ctx,
struct tevent_req *req,
struct ldb_result **_result,
bool *_dp_success)
{
struct cache_req_search_state *state = NULL;
state = tevent_req_data(req, struct cache_req_search_state);
*_dp_success = state->dp_success;
TEVENT_REQ_RETURN_ON_ERROR(req);
*_result = talloc_steal(mem_ctx, state->result);
return EOK;
}