/* tcpclt.c
*
* This is the implementation of TCP-based syslog clients (the counterpart
* of the tcpsrv class).
*
* Copyright 2007, 2008 Rainer Gerhards and Adiscon GmbH.
*
* This file is part of rsyslog.
*
* Rsyslog 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.
*
* Rsyslog 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 Rsyslog. If not, see .
*
* A copy of the GPL can be found in the file "COPYING" in this distribution.
*/
#include "config.h"
#include "rsyslog.h"
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#if HAVE_FCNTL_H
#include
#endif
#include "dirty.h"
#include "syslogd-types.h"
#include "net.h"
#include "tcpclt.h"
#include "module-template.h"
#include "srUtils.h"
MODULE_TYPE_LIB
/* static data */
DEFobjStaticHelpers
/* Initialize TCP sockets (for sender)
*/
static int
CreateSocket(struct addrinfo *addrDest)
{
int fd;
struct addrinfo *r;
r = addrDest;
while(r != NULL) {
fd = socket(r->ai_family, r->ai_socktype, r->ai_protocol);
if (fd != -1) {
/* We can not allow the TCP sender to block syslogd, at least
* not in a single-threaded design. That would cause rsyslogd to
* loose input messages - which obviously also would affect
* other selector lines, too. So we do set it to non-blocking and
* handle the situation ourselfs (by discarding messages). IF we run
* dual-threaded, however, the situation is different: in this case,
* the receivers and the selector line processing are only loosely
* coupled via a memory buffer. Now, I think, we can afford the extra
* wait time. Thus, we enable blocking mode for TCP if we compile with
* pthreads. -- rgerhards, 2005-10-25
* And now, we always run on multiple threads... -- rgerhards, 2007-12-20
*/
if (connect (fd, r->ai_addr, r->ai_addrlen) != 0) {
if(errno == EINPROGRESS) {
/* this is normal - will complete later select */
return fd;
} else {
char errStr[1024];
dbgprintf("create tcp connection failed, reason %s",
rs_strerror_r(errno, errStr, sizeof(errStr)));
}
}
else {
return fd;
}
close(fd);
}
else {
char errStr[1024];
dbgprintf("couldn't create send socket, reason %s", rs_strerror_r(errno, errStr, sizeof(errStr)));
}
r = r->ai_next;
}
dbgprintf("no working socket could be obtained");
return -1;
}
/* Build frame based on selected framing
* This function was created by pulling code from TCPSend()
* on 2007-12-27 by rgerhards. Older comments are still relevant.
*
* In order to support compressed messages via TCP, we must support an
* octet-counting based framing (LF may be part of the compressed message).
* We are now supporting the same mode that is available in IETF I-D
* syslog-transport-tls-05 (current at the time of this writing). This also
* eases things when we go ahead and implement that framing. I have now made
* available two cases where this framing is used: either by explitely
* specifying it in the config file or implicitely when sending a compressed
* message. In the later case, compressed and uncompressed messages within
* the same session have different framings. If it is explicitely set to
* octet-counting, only this framing mode is used within the session.
* rgerhards, 2006-12-07
*/
static rsRetVal
TCPSendBldFrame(tcpclt_t *pThis, char **pmsg, size_t *plen, int *pbMustBeFreed)
{
DEFiRet;
TCPFRAMINGMODE framingToUse;
int bIsCompressed;
size_t len;
char *msg;
char *buf = NULL; /* if this is non-NULL, it MUST be freed before return! */
assert(plen != NULL);
assert(pbMustBeFreed != NULL);
assert(pmsg != NULL);
msg = *pmsg;
len = *plen;
bIsCompressed = *msg == 'z'; /* cache this, so that we can modify the message buffer */
/* select framing for this record. If we have a compressed record, we always need to
* use octet counting because the data potentially contains all control characters
* including LF.
*/
framingToUse = bIsCompressed ? TCP_FRAMING_OCTET_COUNTING : pThis->tcp_framing;
/* now check if we need to add a line terminator. We need to
* copy the string in memory in this case, this is probably
* quicker than using writev and definitely quicker than doing
* two socket calls.
* rgerhards 2005-07-22
*
* Some messages already contain a \n character at the end
* of the message. We append one only if we there is not
* already one. This seems the best fit, though this also
* means the message does not arrive unaltered at the final
* destination. But in the spirit of legacy syslog, this is
* probably the best to do...
* rgerhards 2005-07-20
*/
/* Build frame based on selected framing */
if(framingToUse == TCP_FRAMING_OCTET_STUFFING) {
if((*(msg+len-1) != '\n')) {
/* in the malloc below, we need to add 2 to the length. The
* reason is that we a) add one character and b) len does
* not take care of the '\0' byte. Up until today, it was just
* +1 , which caused rsyslogd to sometimes dump core.
* I have added this comment so that the logic is not accidently
* changed again. rgerhards, 2005-10-25
*/
if((buf = MALLOC((len + 2) * sizeof(char))) == NULL) {
/* extreme mem shortage, try to solve
* as good as we can. No point in calling
* any alarms, they might as well run out
* of memory (the risk is very high, so we
* do NOT risk that). If we have a message of
* more than 1 byte (what I guess), we simply
* overwrite the last character.
* rgerhards 2005-07-22
*/
if(len > 1) {
*(msg+len-1) = '\n';
} else {
/* we simply can not do anything in
* this case (its an error anyhow...).
*/
}
} else {
/* we got memory, so we can copy the message */
memcpy(buf, msg, len); /* do not copy '\0' */
*(buf+len) = '\n';
*(buf+len+1) = '\0';
msg = buf; /* use new one */
++len; /* care for the \n */
}
}
} else {
/* Octect-Counting
* In this case, we need to always allocate a buffer. This is because
* we need to put a header in front of the message text
*/
char szLenBuf[16];
int iLenBuf;
/* important: the printf-mask is "%d" because there must be a
* space after the len!
*//* The chairs of the IETF syslog-sec WG have announced that it is
* consensus to do the octet count on the SYSLOG-MSG part only. I am
* now changing the code to reflect this. Hopefully, it will not change
* once again (there can no compatibility layer programmed for this).
* To be on the save side, I just comment the code out. I mark these
* comments with "IETF20061218".
* rgerhards, 2006-12-19
*/
iLenBuf = snprintf(szLenBuf, sizeof(szLenBuf)/sizeof(char), "%d ", (int) len);
/* IETF20061218 iLenBuf =
snprintf(szLenBuf, sizeof(szLenBuf)/sizeof(char), "%d ", len + iLenBuf);*/
if((buf = MALLOC((len + iLenBuf) * sizeof(char))) == NULL) {
/* we are out of memory. This is an extreme situation. We do not
* call any alarm handlers because they most likely run out of mem,
* too. We are brave enough to call debug output, though. Other than
* that, there is nothing left to do. We can not sent the message (as
* in case of the other framing, because the message is incomplete.
* We could, however, send two chunks (header and text separate), but
* that would cause a lot of complexity in the code. So we think it
* is appropriate enough to just make sure we do not crash in this
* very unlikely case. For this, it is justified just to loose
* the message. Rgerhards, 2006-12-07
*/
dbgprintf("Error: out of memory when building TCP octet-counted "
"frame. Message is lost, trying to continue.\n");
ABORT_FINALIZE(RS_RET_OUT_OF_MEMORY);
}
memcpy(buf, szLenBuf, iLenBuf); /* header */
memcpy(buf + iLenBuf, msg, len); /* message */
len += iLenBuf; /* new message size */
msg = buf; /* set message buffer */
}
/* frame building complete, on to actual sending */
*plen = len;
if(buf == NULL) {
/* msg not modified */
*pbMustBeFreed = 0;
} else {
*pmsg = msg;
*pbMustBeFreed = 1;
}
finalize_it:
RETiRet;
}
/* Sends a TCP message. It is first checked if the
* session is open and, if not, it is opened. Then the send
* is tried. If it fails, one silent re-try is made. If the send
* fails again, an error status (-1) is returned. If all goes well,
* 0 is returned. The TCP session is NOT torn down.
* For now, EAGAIN is ignored (causing message loss) - but it is
* hard to do something intelligent in this case. With this
* implementation here, we can not block and/or defer. Things are
* probably a bit better when we move to liblogging. The alternative
* would be to enhance the current select server with buffering and
* write descriptors. This seems not justified, given the expected
* short life span of this code (and the unlikeliness of this event).
* rgerhards 2005-07-06
* This function is now expected to stay. Libloging won't be used for
* that purpose. I have added the param "len", because it is known by the
* caller and so saves us some time. Also, it MUST be given because there
* may be NULs inside msg so that we can not rely on strlen(). Please note
* that the restrictions outlined above do not existin in multi-threaded
* mode, which we assume will now be most often used. So there is no
* real issue with the potential message loss in single-threaded builds.
* rgerhards, 2006-11-30
* I greatly restructured the function to be more generic and work
* with function pointers. So it now can be used with any type of transport,
* as long as it follows stream semantics. This was initially done to
* support plain TCP and GSS via common code.
*/
static int
Send(tcpclt_t *pThis, void *pData, char *msg, size_t len)
{
DEFiRet;
int bDone = 0;
int retry = 0;
int bMsgMustBeFreed = 0;/* must msg be freed at end of function? 0 - no, 1 - yes */
ISOBJ_TYPE_assert(pThis, tcpclt);
assert(pData != NULL);
assert(msg != NULL);
assert(len > 0);
CHKiRet(TCPSendBldFrame(pThis, &msg, &len, &bMsgMustBeFreed));
if(pThis->iRebindInterval > 0 && ++pThis->iNumMsgs == pThis->iRebindInterval) {
/* we need to rebind, and use the retry logic for this*/
CHKiRet(pThis->prepRetryFunc(pData)); /* try to recover */
pThis->iNumMsgs = 0;
}
while(!bDone) { /* loop is broken when send succeeds or error occurs */
CHKiRet(pThis->initFunc(pData));
iRet = pThis->sendFunc(pData, msg, len);
if(iRet == RS_RET_OK) {
/* we are done, we also use this as indication that the previous
* message was succesfully received (it's not always the case, but its at
* least our best shot at it -- rgerhards, 2008-03-12
* As of 2008-06-09, we have implemented an algorithm which detects connection
* loss quite good in some (common) scenarios. Thus, the probability of
* message duplication due to the code below has increased. We so now have
* a config setting, default off, that enables the user to request retransmits.
* However, if not requested, we do NOT need to do all the stuff needed for it.
*/
if(pThis->bResendLastOnRecon == 1) {
if(pThis->prevMsg != NULL)
free(pThis->prevMsg);
/* if we can not alloc a new buffer, we silently ignore it. The worst that
* happens is that we lose our message recovery buffer - anything else would
* be worse, so don't try anything ;) -- rgerhards, 2008-03-12
*/
if((pThis->prevMsg = MALLOC(len)) != NULL) {
memcpy(pThis->prevMsg, msg, len);
pThis->lenPrevMsg = len;
}
}
/* we are done with this record */
bDone = 1;
} else {
if(retry == 0) { /* OK, one retry */
++retry;
CHKiRet(pThis->prepRetryFunc(pData)); /* try to recover */
/* now try to send our stored previous message (which most probably
* didn't make it. Note that if bResendLastOnRecon is 0, prevMsg will
* never become non-NULL, so the check below covers all cases.
*/
if(pThis->prevMsg != NULL) {
CHKiRet(pThis->initFunc(pData));
CHKiRet(pThis->sendFunc(pData, pThis->prevMsg, pThis->lenPrevMsg));
}
} else {
/* OK, max number of retries reached, nothing we can do */
bDone = 1;
}
}
}
finalize_it:
if(bMsgMustBeFreed)
free(msg);
RETiRet;
}
/* set functions */
static rsRetVal
SetResendLastOnRecon(tcpclt_t *pThis, int bResendLastOnRecon)
{
DEFiRet;
pThis->bResendLastOnRecon = (short) bResendLastOnRecon;
RETiRet;
}
static rsRetVal
SetSendInit(tcpclt_t *pThis, rsRetVal (*pCB)(void*))
{
DEFiRet;
pThis->initFunc = pCB;
RETiRet;
}
static rsRetVal
SetSendPrepRetry(tcpclt_t *pThis, rsRetVal (*pCB)(void*))
{
DEFiRet;
pThis->prepRetryFunc = pCB;
RETiRet;
}
static rsRetVal
SetSendFrame(tcpclt_t *pThis, rsRetVal (*pCB)(void*, char*, size_t))
{
DEFiRet;
pThis->sendFunc = pCB;
RETiRet;
}
static rsRetVal
SetFraming(tcpclt_t *pThis, TCPFRAMINGMODE framing)
{
DEFiRet;
pThis->tcp_framing = framing;
RETiRet;
}
static rsRetVal
SetRebindInterval(tcpclt_t *pThis, int iRebindInterval)
{
DEFiRet;
pThis->iRebindInterval = iRebindInterval;
RETiRet;
}
/* Standard-Constructor
*/
BEGINobjConstruct(tcpclt) /* be sure to specify the object type also in END macro! */
ENDobjConstruct(tcpclt)
/* ConstructionFinalizer
*/
static rsRetVal
tcpcltConstructFinalize(tcpclt_t __attribute__((unused)) *pThis)
{
DEFiRet;
ISOBJ_TYPE_assert(pThis, tcpclt);
RETiRet;
}
/* destructor for the tcpclt object */
BEGINobjDestruct(tcpclt) /* be sure to specify the object type also in END and CODESTART macros! */
CODESTARTobjDestruct(tcpclt)
if(pThis->prevMsg != NULL)
free(pThis->prevMsg);
ENDobjDestruct(tcpclt)
/* ------------------------------ handling the interface plumbing ------------------------------ */
/* queryInterface function
* rgerhards, 2008-03-12
*/
BEGINobjQueryInterface(tcpclt)
CODESTARTobjQueryInterface(tcpclt)
if(pIf->ifVersion != tcpcltCURR_IF_VERSION) { /* check for current version, increment on each change */
ABORT_FINALIZE(RS_RET_INTERFACE_NOT_SUPPORTED);
}
/* ok, we have the right interface, so let's fill it
* Please note that we may also do some backwards-compatibility
* work here (if we can support an older interface version - that,
* of course, also affects the "if" above).
*/
pIf->Construct = tcpcltConstruct;
pIf->ConstructFinalize = tcpcltConstructFinalize;
pIf->Destruct = tcpcltDestruct;
pIf->CreateSocket = CreateSocket;
pIf->Send = Send;
/* set functions */
pIf->SetResendLastOnRecon = SetResendLastOnRecon;
pIf->SetSendInit = SetSendInit;
pIf->SetSendFrame = SetSendFrame;
pIf->SetSendPrepRetry = SetSendPrepRetry;
pIf->SetFraming = SetFraming;
pIf->SetRebindInterval = SetRebindInterval;
finalize_it:
ENDobjQueryInterface(tcpclt)
/* exit our class
* rgerhards, 2008-03-10
*/
BEGINObjClassExit(tcpclt, OBJ_IS_LOADABLE_MODULE) /* CHANGE class also in END MACRO! */
CODESTARTObjClassExit(tcpclt)
/* release objects we no longer need */
ENDObjClassExit(tcpclt)
/* Initialize our class. Must be called as the very first method
* before anything else is called inside this class.
* rgerhards, 2008-02-29
*/
BEGINObjClassInit(tcpclt, 1, OBJ_IS_LOADABLE_MODULE) /* class, version - CHANGE class also in END MACRO! */
/* request objects we use */
/* set our own handlers */
OBJSetMethodHandler(objMethod_CONSTRUCTION_FINALIZER, tcpcltConstructFinalize);
ENDObjClassInit(tcpclt)
/* --------------- here now comes the plumbing that makes as a library module --------------- */
BEGINmodExit
CODESTARTmodExit
/* de-init in reverse order! */
tcpcltClassExit();
ENDmodExit
BEGINqueryEtryPt
CODESTARTqueryEtryPt
CODEqueryEtryPt_STD_LIB_QUERIES
ENDqueryEtryPt
BEGINmodInit()
CODESTARTmodInit
*ipIFVersProvided = CURR_MOD_IF_VERSION; /* we only support the current interface specification */
/* Initialize all classes that are in our module - this includes ourselfs */
CHKiRet(tcpcltClassInit(pModInfo)); /* must be done after tcps_sess, as we use it */
ENDmodInit
/*
* vi:set ai:
*/