summaryrefslogtreecommitdiffstats
path: root/plugins/imudp/imudp.c
blob: 31a4869f8b26facd1c31d602166ab78c5d695a32 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
/* imudp.c
 * This is the implementation of the UDP input module.
 *
 * NOTE: read comments in module-template.h to understand how this file
 *       works!
 *
 * File begun on 2007-12-21 by RGerhards (extracted from syslogd.c)
 *
 * Copyright 2007-2009 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 <http://www.gnu.org/licenses/>.
 *
 * A copy of the GPL can be found in the file "COPYING" in this distribution.
 */
#include "config.h"
#include <stdlib.h>
#include <assert.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
#include <netdb.h>
#include "rsyslog.h"
#include "dirty.h"
#include "net.h"
#include "cfsysline.h"
#include "module-template.h"
#include "srUtils.h"
#include "errmsg.h"
#include "glbl.h"
#include "msg.h"
#include "parser.h"
#include "datetime.h"
#include "prop.h"
#include "unicode-helper.h"

MODULE_TYPE_INPUT

/* defines */

/* Module static data */
DEF_IMOD_STATIC_DATA
DEFobjCurrIf(errmsg)
DEFobjCurrIf(glbl)
DEFobjCurrIf(net)
DEFobjCurrIf(datetime)
DEFobjCurrIf(prop)

static int iMaxLine;			/* maximum UDP message size supported */
static time_t ttLastDiscard = 0;	/* timestamp when a message from a non-permitted sender was last discarded
					 * This shall prevent remote DoS when the "discard on disallowed sender"
					 * message is configured to be logged on occurance of such a case.
					 */
static int *udpLstnSocks = NULL;	/* Internet datagram sockets, first element is nbr of elements
					 * read-only after init(), but beware of restart! */
static uchar *pszBindAddr = NULL;	/* IP to bind socket to */
static uchar *pRcvBuf = NULL;		/* receive buffer (for a single packet). We use a global and alloc
					 * it so that we can check available memory in willRun() and request
					 * termination if we can not get it. -- rgerhards, 2007-12-27
					 */
static prop_t *pInputName = NULL;	/* our inputName currently is always "imudp", and this will hold it */
// TODO: static ruleset_t *pBindRuleset = NULL; /* ruleset to bind listener to (use system default if unspecified) */
#define TIME_REQUERY_DFLT 2
static int iTimeRequery = TIME_REQUERY_DFLT;/* how often is time to be queried inside tight recv loop? 0=always */

/* config settings */


/* This function is called when a new listener shall be added. It takes
 * the configured parameters, tries to bind the socket and, if that
 * succeeds, adds it to the list of existing listen sockets.
 * rgerhards, 2007-12-27
 */
static rsRetVal addListner(void __attribute__((unused)) *pVal, uchar *pNewVal)
{
	DEFiRet;
	uchar *bindAddr;
	int *newSocks;
	int *tmpSocks;
	int iSrc, iDst;

	/* check which address to bind to. We could do this more compact, but have not
	 * done so in order to make the code more readable. -- rgerhards, 2007-12-27
	 */
	if(pszBindAddr == NULL)
		bindAddr = NULL;
	else if(pszBindAddr[0] == '*' && pszBindAddr[1] == '\0')
		bindAddr = NULL;
	else
		bindAddr = pszBindAddr;

	DBGPRINTF("Trying to open syslog UDP ports at %s:%s.\n",
		  (bindAddr == NULL) ? (uchar*)"*" : bindAddr, pNewVal);

	newSocks = net.create_udp_socket(bindAddr, (pNewVal == NULL || *pNewVal == '\0') ? (uchar*) "514" : pNewVal, 1);
	if(newSocks != NULL) {
		/* we now need to add the new sockets to the existing set */
		if(udpLstnSocks == NULL) {
			/* esay, we can just replace it */
			udpLstnSocks = newSocks;
		} else {
			/* we need to add them */
			if((tmpSocks = malloc(sizeof(int) * (1 + newSocks[0] + udpLstnSocks[0]))) == NULL) {
				dbgprintf("out of memory trying to allocate udp listen socket array\n");
				/* in this case, we discard the new sockets but continue with what we
				 * already have
				 */
				free(newSocks);
				ABORT_FINALIZE(RS_RET_OUT_OF_MEMORY);
			} else {
				/* ready to copy */
				iDst = 1;
				for(iSrc = 1 ; iSrc <= udpLstnSocks[0] ; ++iSrc)
					tmpSocks[iDst++] = udpLstnSocks[iSrc];
				for(iSrc = 1 ; iSrc <= newSocks[0] ; ++iSrc)
					tmpSocks[iDst++] = newSocks[iSrc];
				tmpSocks[0] = udpLstnSocks[0] + newSocks[0];
				free(newSocks);
				free(udpLstnSocks);
				udpLstnSocks = tmpSocks;
			}
		}
	}

finalize_it:
	free(pNewVal); /* in any case, this is no longer needed */

	RETiRet;
}


#if 0 /* TODO: implement when tehre is time, requires restructure of socket array! */
/* accept a new ruleset to bind. Checks if it exists and complains, if not */
static rsRetVal
setRuleset(void __attribute__((unused)) *pVal, uchar *pszName)
{
	ruleset_t *pRuleset;
	rsRetVal localRet;
	DEFiRet;

	localRet = ruleset.GetRuleset(&pRuleset, pszName);
	if(localRet == RS_RET_NOT_FOUND) {
		errmsg.LogError(0, NO_ERRCODE, "error: ruleset '%s' not found - ignored", pszName);
	}
	CHKiRet(localRet);
	pBindRuleset = pRuleset;
	DBGPRINTF("imudp current bind ruleset %p: '%s'\n", pRuleset, pszName);

finalize_it:
	free(pszName); /* no longer needed */
	RETiRet;
}
#endif


/* This function is a helper to runInput. I have extracted it
 * from the main loop just so that we do not have that large amount of code
 * in a single place. This function takes a socket and pulls messages from
 * it until the socket does not have any more waiting.
 * rgerhards, 2008-01-08
 * We try to read from the file descriptor until there
 * is no more data. This is done in the hope to get better performance
 * out of the system. However, this also means that a descriptor
 * monopolizes processing while it contains data. This can lead to
 * data loss in other descriptors. However, if the system is incapable of
 * handling the workload, we will loss data in any case. So it doesn't really
 * matter where the actual loss occurs - it is always random, because we depend
 * on scheduling order. -- rgerhards, 2008-10-02
 */
static inline rsRetVal
processSocket(int fd, struct sockaddr_storage *frominetPrev, int *pbIsPermitted,
	      uchar *fromHost, uchar *fromHostFQDN, uchar *fromHostIP)
{
	DEFiRet;
	int iNbrTimeUsed;
	time_t ttGenTime;
	struct syslogTime stTime;
	socklen_t socklen;
	ssize_t lenRcvBuf;
	struct sockaddr_storage frominet;
	msg_t *pMsg;
	char errStr[1024];

	iNbrTimeUsed = 0;
	while(1) { /* loop is terminated if we have a bad receive, done below in the body */
		socklen = sizeof(struct sockaddr_storage);
		lenRcvBuf = recvfrom(fd, (char*) pRcvBuf, iMaxLine, 0, (struct sockaddr *)&frominet, &socklen);
		if(lenRcvBuf < 0) {
			if(errno != EINTR && errno != EAGAIN) {
				rs_strerror_r(errno, errStr, sizeof(errStr));
				DBGPRINTF("INET socket error: %d = %s.\n", errno, errStr);
				errmsg.LogError(errno, NO_ERRCODE, "recvfrom inet");
			}
			ABORT_FINALIZE(RS_RET_ERR);
		}

		/* if we reach this point, we had a good receive and can process the packet received */
		/* check if we have a different sender than before, if so, we need to query some new values */
		if(memcmp(&frominet, frominetPrev, socklen) != 0) {
			CHKiRet(net.cvthname(&frominet, fromHost, fromHostFQDN, fromHostIP));
			memcpy(frominetPrev, &frominet, socklen); /* update cache indicator */
			/* Here we check if a host is permitted to send us
			* syslog messages. If it isn't, we do not further
			* process the message but log a warning (if we are
			* configured to do this).
			* rgerhards, 2005-09-26
			*/
			*pbIsPermitted = net.isAllowedSender((uchar*)"UDP",
			  			            (struct sockaddr *)&frominet, (char*)fromHostFQDN);
	
			if(!*pbIsPermitted) {
				DBGPRINTF("%s is not an allowed sender\n", (char*)fromHostFQDN);
				if(glbl.GetOption_DisallowWarning) {
					time_t tt;

					time(&tt);
					if(tt > ttLastDiscard + 60) {
						ttLastDiscard = tt;
						errmsg.LogError(0, NO_ERRCODE,
						"UDP message from disallowed sender %s discarded",
						(char*)fromHost);
					}
				}
			}
		}

		DBGPRINTF("recv(%d,%d)/%s,acl:%d,msg:%.80s\n", fd, (int) lenRcvBuf, fromHost, *pbIsPermitted, pRcvBuf);

		if(*pbIsPermitted)  {
			if((iTimeRequery == 0) || (iNbrTimeUsed++ % iTimeRequery) == 0) {
				datetime.getCurrTime(&stTime, &ttGenTime);
			}
			/* we now create our own message object and submit it to the queue */
			CHKiRet(msgConstructWithTime(&pMsg, &stTime, ttGenTime));
			MsgSetRawMsg(pMsg, (char*)pRcvBuf, lenRcvBuf);
			MsgSetInputName(pMsg, pInputName);
			MsgSetFlowControlType(pMsg, eFLOWCTL_NO_DELAY);
			pMsg->msgFlags  = NEEDS_PARSING | PARSE_HOSTNAME;
			pMsg->bParseHOSTNAME = 1;
			MsgSetRcvFromStr(pMsg, fromHost, ustrlen(fromHost));
			CHKiRet(MsgSetRcvFromIPStr(pMsg, fromHostIP, ustrlen(fromHostIP)));
			CHKiRet(submitMsg(pMsg));
		}
	}


finalize_it:
	RETiRet;
}


/* This function is called to gather input.
 * Note that udpLstnSocks must be non-NULL because otherwise we would not have
 * indicated that we want to run (or we have a programming error ;)). -- rgerhards, 2008-10-02
 * rgerhards, 2008-10-07: I have implemented a very simple, yet in most cases probably
 * highly efficient "name caching". Before querying a name, I now check if the name to be
 * queried is the same as the one queried in the last message processed. If that is the
 * case, we can simple re-use the previous value. This algorithm works quite well with
 * few sender, especially if they emit messages in bursts. The more sender and the
 * more intermixed messages arrive, the less this algorithm works, but the overhead
 * is so minimal (a simple memory compare and move) that this does not hurt. Even
 * with a real name lookup cache, this optimization here is useful as it is quicker
 * than even a cache lookup).
 */
BEGINrunInput
	int maxfds;
	int nfds;
	int i;
	fd_set readfds;
	struct sockaddr_storage frominetPrev;
	int bIsPermitted;
	uchar fromHost[NI_MAXHOST];
	uchar fromHostIP[NI_MAXHOST];
	uchar fromHostFQDN[NI_MAXHOST];
CODESTARTrunInput
	/* start "name caching" algo by making sure the previous system indicator
	 * is invalidated.
	 */
	bIsPermitted = 0;
	memset(&frominetPrev, 0, sizeof(frominetPrev));
	/* this is an endless loop - it is terminated when the thread is
	 * signalled to do so. This, however, is handled by the framework,
	 * right into the sleep below.
	 */
	while(1) {
		/* Add the Unix Domain Sockets to the list of read
		 * descriptors.
		 * rgerhards 2005-08-01: we must now check if there are
		 * any local sockets to listen to at all. If the -o option
		 * is given without -a, we do not need to listen at all..
		 */
	        maxfds = 0;
	        FD_ZERO (&readfds);

		/* Add the UDP listen sockets to the list of read descriptors. */
		for (i = 0; i < *udpLstnSocks; i++) {
			if (udpLstnSocks[i+1] != -1) {
				if(Debug)
					net.debugListenInfo(udpLstnSocks[i+1], "UDP");
				FD_SET(udpLstnSocks[i+1], &readfds);
				if(udpLstnSocks[i+1]>maxfds) maxfds=udpLstnSocks[i+1];
			}
		}
		if(Debug) {
			dbgprintf("--------imUDP calling select, active file descriptors (max %d): ", maxfds);
			for (nfds = 0; nfds <= maxfds; ++nfds)
				if ( FD_ISSET(nfds, &readfds) )
					dbgprintf("%d ", nfds);
			dbgprintf("\n");
		}

		/* wait for io to become ready */
		nfds = select(maxfds+1, (fd_set *) &readfds, NULL, NULL, NULL);

	       for(i = 0; nfds && i < *udpLstnSocks; i++) {
			if(FD_ISSET(udpLstnSocks[i+1], &readfds)) {
		       		processSocket(udpLstnSocks[i+1], &frominetPrev, &bIsPermitted,
					      fromHost, fromHostFQDN, fromHostIP);
			--nfds; /* indicate we have processed one descriptor */
			}
	       }
	       /* end of a run, back to loop for next recv() */
	}

	return iRet;
ENDrunInput


/* initialize and return if will run or not */
BEGINwillRun
CODESTARTwillRun
	/* we need to create the inputName property (only once during our lifetime) */
	CHKiRet(prop.Construct(&pInputName));
	CHKiRet(prop.SetString(pInputName, UCHAR_CONSTANT("imudp"), sizeof("imudp") - 1));
	CHKiRet(prop.ConstructFinalize(pInputName));

	net.PrintAllowedSenders(1); /* UDP */

	/* if we could not set up any listners, there is no point in running... */
	if(udpLstnSocks == NULL)
		ABORT_FINALIZE(RS_RET_NO_RUN);

	iMaxLine = glbl.GetMaxLine();

	if((pRcvBuf = malloc((iMaxLine + 1) * sizeof(char))) == NULL) {
		ABORT_FINALIZE(RS_RET_OUT_OF_MEMORY);
	}
finalize_it:
ENDwillRun


BEGINafterRun
CODESTARTafterRun
	/* do cleanup here */
	net.clearAllowedSenders((uchar*)"UDP");
	if(udpLstnSocks != NULL) {
		net.closeUDPListenSockets(udpLstnSocks);
		udpLstnSocks = NULL;
	}
	if(pRcvBuf != NULL) {
		free(pRcvBuf);
		pRcvBuf = NULL;
	}
	if(pInputName != NULL)
		prop.Destruct(&pInputName);
ENDafterRun


BEGINmodExit
CODESTARTmodExit
	/* release what we no longer need */
	objRelease(errmsg, CORE_COMPONENT);
	objRelease(glbl, CORE_COMPONENT);
	objRelease(datetime, CORE_COMPONENT);
	objRelease(prop, CORE_COMPONENT);
	objRelease(net, LM_NET_FILENAME);
ENDmodExit


BEGINqueryEtryPt
CODESTARTqueryEtryPt
CODEqueryEtryPt_STD_IMOD_QUERIES
ENDqueryEtryPt

static rsRetVal resetConfigVariables(uchar __attribute__((unused)) *pp, void __attribute__((unused)) *pVal)
{
	if(pszBindAddr != NULL) {
		free(pszBindAddr);
		pszBindAddr = NULL;
	}
	if(udpLstnSocks != NULL) {
		net.closeUDPListenSockets(udpLstnSocks);
		udpLstnSocks = NULL;
	}
	iTimeRequery = TIME_REQUERY_DFLT;/* the default is to query only every second time */
	return RS_RET_OK;
}


BEGINmodInit()
CODESTARTmodInit
	*ipIFVersProvided = CURR_MOD_IF_VERSION; /* we only support the current interface specification */
CODEmodInit_QueryRegCFSLineHdlr
	CHKiRet(objUse(errmsg, CORE_COMPONENT));
	CHKiRet(objUse(glbl, CORE_COMPONENT));
	CHKiRet(objUse(datetime, CORE_COMPONENT));
	CHKiRet(objUse(prop, CORE_COMPONENT));
	CHKiRet(objUse(net, LM_NET_FILENAME));

	/* register config file handlers */
	/* TODO: add - but this requires more changes, no time right now...
	CHKiRet(omsdRegCFSLineHdlr((uchar *)"udpserverbindruleset", 0, eCmdHdlrGetWord,
		setRuleset, NULL, STD_LOADABLE_MODULE_ID));
	*/
	CHKiRet(omsdRegCFSLineHdlr((uchar *)"udpserverrun", 0, eCmdHdlrGetWord,
		addListner, NULL, STD_LOADABLE_MODULE_ID));
	CHKiRet(omsdRegCFSLineHdlr((uchar *)"udpserveraddress", 0, eCmdHdlrGetWord,
		NULL, &pszBindAddr, STD_LOADABLE_MODULE_ID));
	CHKiRet(omsdRegCFSLineHdlr((uchar *)"udpservertimerequery", 0, eCmdHdlrInt,
		NULL, &iTimeRequery, STD_LOADABLE_MODULE_ID));
	CHKiRet(omsdRegCFSLineHdlr((uchar *)"resetconfigvariables", 1, eCmdHdlrCustomHandler,
		resetConfigVariables, NULL, STD_LOADABLE_MODULE_ID));
ENDmodInit
/* vim:set ai:
 */