path: root/runtime/netstrm.c

/* netstrmstrm.c
 * 
 * This class implements a generic netstrmwork stream class. It supports
 * sending and receiving data streams over a netstrmwork. The class abstracts
 * the transport, though it is a safe assumption that TCP is being used.
 * The class has a number of properties, among which are also ones to
 * select privacy settings, eg by enabling TLS and/or GSSAPI. In the 
 * long run, this class shall provide all stream-oriented netstrmwork
 * functionality inside rsyslog.
 *
 * It is a high-level class, which uses a number of helper objects
 * to carry out its work (including, and most importantly, transport
 * drivers).
 *
 * Copyright 2007, 2008 Rainer Gerhards and Adiscon GmbH.
 *
 * This file is part of the rsyslog runtime library.
 *
 * The rsyslog runtime library is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * The rsyslog runtime library 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 Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with the rsyslog runtime library.  If not, see <http://www.gnu.org/licenses/>.
 *
 * A copy of the GPL can be found in the file "COPYING" in this distribution.
 * A copy of the LGPL can be found in the file "COPYING.LESSER" in this distribution.
 */
#include "config.h"

#include "rsyslog.h"
#include <stdio.h>
#include <stdarg.h>
#include <stdlib.h>
#include <assert.h>
#include <errno.h>
#include <string.h>
#include <signal.h>
#include <ctype.h>
#include <netdb.h>
#include <fnmatch.h>
#include <fcntl.h>
#include <unistd.h>

#include "syslogd-types.h"
#include "module-template.h"
#include "parse.h"
#include "srUtils.h"
#include "obj.h"
#include "errmsg.h"
#include "netstrm.h"

MODULE_TYPE_LIB

/* static data */
DEFobjStaticHelpers
DEFobjCurrIf(errmsg)
DEFobjCurrIf(glbl)


/* The following #ifdef sequence is a small compatibility 
 * layer. It tries to work around the different availality
 * levels of SO_BSDCOMPAT on linuxes...
 * I borrowed this code from
 *    http://www.erlang.org/ml-archive/erlang-questions/200307/msg00037.html
 * It still needs to be a bit better adapted to rsyslog.
 * rgerhards 2005-09-19
 */
#include <sys/utsname.h>
static int
should_use_so_bsdcompat(void)
{
#ifndef OS_BSD
    static int init_done;
    static int so_bsdcompat_is_obsolete;

    if (!init_done) {
	struct utsname myutsname;
	unsigned int version, patchlevel;

	init_done = 1;
	if (uname(&myutsname) < 0) {
		char errStr[1024];
		dbgprintf("uname: %s\r\n", rs_strerror_r(errno, errStr, sizeof(errStr)));
		return 1;
	}
	/* Format is <version>.<patchlevel>.<sublevel><extraversion>
	   where the first three are unsigned integers and the last
	   is an arbitrary string. We only care about the first two. */
	if (sscanf(myutsname.release, "%u.%u", &version, &patchlevel) != 2) {
	    dbgprintf("uname: unexpected release '%s'\r\n",
		    myutsname.release);
	    return 1;
	}
	/* SO_BSCOMPAT is deprecated and triggers warnings in 2.5
	   kernels. It is a no-op in 2.4 but not in 2.2 kernels. */
	if (version > 2 || (version == 2 && patchlevel >= 5))
	    so_bsdcompat_is_obsolete = 1;
    }
    return !so_bsdcompat_is_obsolete;
#else	/* #ifndef OS_BSD */
    return 1;
#endif	/* #ifndef OS_BSD */
}
#ifndef SO_BSDCOMPAT
/* this shall prevent compiler errors due to undfined name */
#define SO_BSDCOMPAT 0
#endif


/* get the hostname of the message source. This was originally in cvthname()
 * but has been moved out of it because of clarity and fuctional separation.
 * It must be provided by the socket we received the message on as well as
 * a NI_MAXHOST size large character buffer for the FQDN.
 *
 * Please see http://www.hmug.org/man/3/getnameinfo.php (under Caveats)
 * for some explanation of the code found below. We do by default not
 * discard message where we detected malicouos DNS PTR records. However,
 * there is a user-configurabel option that will tell us if
 * we should abort. For this, the return value tells the caller if the
 * message should be processed (1) or discarded (0).
 */
static rsRetVal
gethname(struct sockaddr_storage *f, uchar *pszHostFQDN)
{
	DEFiRet;
	int error;
	sigset_t omask, nmask;
	char ip[NI_MAXHOST];
	struct addrinfo hints, *res;
	
	assert(f != NULL);
	assert(pszHostFQDN != NULL);

        error = getnameinfo((struct sockaddr *)f, SALEN((struct sockaddr *)f),
			    ip, sizeof ip, NULL, 0, NI_NUMERICHOST);

        if (error) {
                dbgprintf("Malformed from address %s\n", gai_strerror(error));
		strcpy((char*) pszHostFQDN, "???");
		ABORT_FINALIZE(RS_RET_INVALID_SOURCE);
	}

	if(!glbl.GetDisableDNS()) {
		sigemptyset(&nmask);
		sigaddset(&nmask, SIGHUP);
		pthread_sigmask(SIG_BLOCK, &nmask, &omask);

		error = getnameinfo((struct sockaddr *)f, SALEN((struct sockaddr *) f),
				    (char*)pszHostFQDN, NI_MAXHOST, NULL, 0, NI_NAMEREQD);
		
		if (error == 0) {
			memset (&hints, 0, sizeof (struct addrinfo));
			hints.ai_flags = AI_NUMERICHOST;
			hints.ai_socktype = SOCK_STREAM;

			/* we now do a lookup once again. This one should fail,
			 * because we should not have obtained a non-numeric address. If
			 * we got a numeric one, someone messed with DNS!
			 */
			if (getaddrinfo ((char*)pszHostFQDN, NULL, &hints, &res) == 0) {
				uchar szErrMsg[1024];
				freeaddrinfo (res);
				/* OK, we know we have evil. The question now is what to do about
				 * it. One the one hand, the message might probably be intended
				 * to harm us. On the other hand, losing the message may also harm us.
				 * Thus, the behaviour is controlled by the $DropMsgsWithMaliciousDnsPTRRecords
				 * option. If it tells us we should discard, we do so, else we proceed,
				 * but log an error message together with it.
				 * time being, we simply drop the name we obtained and use the IP - that one
				 * is OK in any way. We do also log the error message. rgerhards, 2007-07-16
		 		 */
		 		if(glbl.GetDropMalPTRMsgs() == 1) {
					snprintf((char*)szErrMsg, sizeof(szErrMsg) / sizeof(uchar),
						 "Malicious PTR record, message dropped "
						 "IP = \"%s\" HOST = \"%s\"",
						 ip, pszHostFQDN);
					errmsg.LogError(NO_ERRCODE, "%s", szErrMsg);
					pthread_sigmask(SIG_SETMASK, &omask, NULL);
					ABORT_FINALIZE(RS_RET_MALICIOUS_ENTITY);
				}

				/* Please note: we deal with a malicous entry. Thus, we have crafted
				 * the snprintf() below so that all text is in front of the entry - maybe
				 * it contains characters that make the message unreadable
				 * (OK, I admit this is more or less impossible, but I am paranoid...)
				 * rgerhards, 2007-07-16
				 */
				snprintf((char*)szErrMsg, sizeof(szErrMsg) / sizeof(uchar),
					 "Malicious PTR record (message accepted, but used IP "
					 "instead of PTR name: IP = \"%s\" HOST = \"%s\"",
					 ip, pszHostFQDN);
				errmsg.LogError(NO_ERRCODE, "%s", szErrMsg);

				error = 1; /* that will trigger using IP address below. */
			}
		}		
		pthread_sigmask(SIG_SETMASK, &omask, NULL);
	}

        if(error || glbl.GetDisableDNS()) {
                dbgprintf("Host name for your address (%s) unknown\n", ip);
		strcpy((char*) pszHostFQDN, ip);
		ABORT_FINALIZE(RS_RET_ADDRESS_UNKNOWN);
        }

finalize_it:
	RETiRet;
}


/* queryInterface function
 * rgerhards, 2008-03-05
 */
BEGINobjQueryInterface(netstrm)
CODESTARTobjQueryInterface(netstrm)
	if(pIf->ifVersion != netstrmCURR_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->cvthname = cvthname;
finalize_it:
ENDobjQueryInterface(netstrm)


/* exit our class
 * rgerhards, 2008-03-10
 */
BEGINObjClassExit(netstrm, OBJ_IS_LOADABLE_MODULE) /* CHANGE class also in END MACRO! */
CODESTARTObjClassExit(netstrm)
	/* release objects we no longer need */
	objRelease(glbl, CORE_COMPONENT);
	objRelease(errmsg, CORE_COMPONENT);
ENDObjClassExit(netstrm)


/* Initialize the netstrm class. Must be called as the very first method
 * before anything else is called inside this class.
 * rgerhards, 2008-02-19
 */
BEGINAbstractObjClassInit(netstrm, 1, OBJ_IS_CORE_MODULE) /* class, version */
	/* request objects we use */
	CHKiRet(objUse(errmsg, CORE_COMPONENT));
	CHKiRet(objUse(glbl, CORE_COMPONENT));

	/* set our own handlers */
ENDObjClassInit(netstrm)


/* --------------- here now comes the plumbing that makes as a library module --------------- */


BEGINmodExit
CODESTARTmodExit
	netstrmClassExit();
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(netstrmClassInit(pModInfo)); /* must be done after tcps_sess, as we use it */
ENDmodInit
/* vi:set ai:
 */