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/* ratelimit.c
* support for rate-limiting sources, including "last message
* repeated n times" processing.
*
* Copyright 2012 Rainer Gerhards and Adiscon GmbH.
*
* This file is part of the rsyslog runtime library.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
* -or-
* see COPYING.ASL20 in the source distribution
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "config.h"
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include "rsyslog.h"
#include "errmsg.h"
#include "ratelimit.h"
#include "datetime.h"
#include "parser.h"
#include "unicode-helper.h"
#include "msg.h"
#include "dirty.h"
/* definitions for objects we access */
DEFobjStaticHelpers
DEFobjCurrIf(errmsg)
DEFobjCurrIf(glbl)
DEFobjCurrIf(datetime)
DEFobjCurrIf(parser)
/* static data */
/* generate a "repeated n times" message */
static inline msg_t *
ratelimitGenRepMsg(ratelimit_t *ratelimit)
{
msg_t *repMsg;
size_t lenRepMsg;
uchar szRepMsg[1024];
if(ratelimit->nsupp == 1) { /* we simply use the original message! */
repMsg = MsgAddRef(ratelimit->pMsg);
} else {/* we need to duplicate, original message may still be in use in other
* parts of the system! */
if((repMsg = MsgDup(ratelimit->pMsg)) == NULL) {
DBGPRINTF("Message duplication failed, dropping repeat message.\n");
goto done;
}
lenRepMsg = snprintf((char*)szRepMsg, sizeof(szRepMsg),
" message repeated %d times: [%.800s]",
ratelimit->nsupp, getMSG(ratelimit->pMsg));
MsgReplaceMSG(repMsg, szRepMsg, lenRepMsg);
}
done: return repMsg;
}
/* ratelimit a message, that means:
* - handle "last message repeated n times" logic
* - handle actual (discarding) rate-limiting
* This function returns RS_RET_OK, if the caller shall process
* the message regularly and RS_RET_DISCARD if the caller must
* discard the message. The caller should also discard the message
* if another return status occurs. This places some burden on the
* caller logic, but provides best performance. Demanding this
* cooperative mode can enable a faulty caller to thrash up part
* of the system, but we accept that risk (a faulty caller can
* always do all sorts of evil, so...)
* If *ppRepMsg != NULL on return, the caller must enqueue that
* message before the original message.
*/
rsRetVal
ratelimitMsg(ratelimit_t *ratelimit, msg_t *pMsg, msg_t **ppRepMsg)
{
rsRetVal localRet;
int bNeedUnlockMutex = 0;
DEFiRet;
if((pMsg->msgFlags & NEEDS_PARSING) != 0) {
if((localRet = parser.ParseMsg(pMsg)) != RS_RET_OK) {
DBGPRINTF("Message discarded, parsing error %d\n", localRet);
ABORT_FINALIZE(RS_RET_DISCARDMSG);
}
}
if(ratelimit->bThreadSafe) {
pthread_mutex_lock(&ratelimit->mut);
bNeedUnlockMutex = 1;
}
*ppRepMsg = NULL;
/* suppress duplicate messages */
if( ratelimit->pMsg != NULL &&
getMSGLen(pMsg) == getMSGLen(ratelimit->pMsg) &&
!ustrcmp(getMSG(pMsg), getMSG(ratelimit->pMsg)) &&
!strcmp(getHOSTNAME(pMsg), getHOSTNAME(ratelimit->pMsg)) &&
!strcmp(getPROCID(pMsg, LOCK_MUTEX), getPROCID(ratelimit->pMsg, LOCK_MUTEX)) &&
!strcmp(getAPPNAME(pMsg, LOCK_MUTEX), getAPPNAME(ratelimit->pMsg, LOCK_MUTEX))) {
ratelimit->nsupp++;
DBGPRINTF("msg repeated %d times\n", ratelimit->nsupp);
/* use current message, so we have the new timestamp
* (means we need to discard previous one) */
msgDestruct(&ratelimit->pMsg);
ratelimit->pMsg = pMsg;
ABORT_FINALIZE(RS_RET_DISCARDMSG);
} else {/* new message, do "repeat processing" & save it */
if(ratelimit->pMsg != NULL) {
if(ratelimit->nsupp > 0) {
*ppRepMsg = ratelimitGenRepMsg(ratelimit);
ratelimit->nsupp = 0;
}
msgDestruct(&ratelimit->pMsg);
}
ratelimit->pMsg = MsgAddRef(pMsg);
}
finalize_it:
if(bNeedUnlockMutex)
pthread_mutex_unlock(&ratelimit->mut);
RETiRet;
}
/* add a message to a ratelimiter/multisubmit structure.
* ratelimiting is automatically handled according to the ratelimit
* settings.
* if pMultiSub == NULL, a single-message enqueue happens (under reconsideration)
*/
rsRetVal
ratelimitAddMsg(ratelimit_t *ratelimit, multi_submit_t *pMultiSub, msg_t *pMsg)
{
rsRetVal localRet;
msg_t *repMsg;
DEFiRet;
if(pMultiSub == NULL) {
dbgprintf("DDDDD: multiSubmitAddMsg, not checking ratelimiter for single submit!\n");
#warning missing multisub Implementation?
CHKiRet(submitMsg(pMsg));
} else {
localRet = ratelimitMsg(ratelimit, pMsg, &repMsg);
if(repMsg != NULL) {
pMultiSub->ppMsgs[pMultiSub->nElem++] = repMsg;
if(pMultiSub->nElem == pMultiSub->maxElem)
CHKiRet(multiSubmitMsg2(pMultiSub));
}
if(localRet == RS_RET_OK) {
pMultiSub->ppMsgs[pMultiSub->nElem++] = pMsg;
if(pMultiSub->nElem == pMultiSub->maxElem)
CHKiRet(multiSubmitMsg2(pMultiSub));
}
}
finalize_it:
RETiRet;
}
rsRetVal
ratelimitNew(ratelimit_t **ppThis)
{
ratelimit_t *pThis;
DEFiRet;
CHKmalloc(pThis = calloc(1, sizeof(ratelimit_t)));
*ppThis = pThis;
finalize_it:
RETiRet;
}
/* enable thread-safe operations mode. This make sure that
* a single ratelimiter can be called from multiple threads. As
* this causes some overhead and is not always required, it needs
* to be explicitely enabled. This operation cannot be undone
* (think: why should one do that???)
*/
void
ratelimitSetThreadSafe(ratelimit_t *ratelimit)
{
ratelimit->bThreadSafe = 1;
pthread_mutex_init(&ratelimit->mut, NULL);
}
void
ratelimitDestruct(ratelimit_t *ratelimit)
{
msg_t *pMsg;
if(ratelimit->pMsg != NULL) {
if(ratelimit->nsupp > 0) {
pMsg = ratelimitGenRepMsg(ratelimit);
if(pMsg != NULL)
submitMsg2(pMsg);
}
msgDestruct(&ratelimit->pMsg);
}
if(ratelimit->bThreadSafe)
pthread_mutex_destroy(&ratelimit->mut);
free(ratelimit);
}
void
ratelimitModExit(void)
{
objRelease(datetime, CORE_COMPONENT);
objRelease(glbl, CORE_COMPONENT);
objRelease(errmsg, CORE_COMPONENT);
objRelease(parser, CORE_COMPONENT);
}
rsRetVal
ratelimitModInit(void)
{
DEFiRet;
CHKiRet(objGetObjInterface(&obj));
CHKiRet(objUse(glbl, CORE_COMPONENT));
CHKiRet(objUse(datetime, CORE_COMPONENT));
CHKiRet(objUse(errmsg, CORE_COMPONENT));
CHKiRet(objUse(parser, CORE_COMPONENT));
finalize_it:
RETiRet;
}
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