/* omsnmp.c
 *
 * This module sends an snmp trap.
 *
 * NOTE: read comments in module-template.h to understand how this file
 *       works!
 *
 * Copyright 2007 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 "rsyslog.h"
#include <stdio.h>
#include <stdarg.h>
#include <stdlib.h>
#include <string.h>
#include <netinet/in.h>
#include <sys/time.h>
#include <sys/socket.h>
#include <netdb.h>
#include <ctype.h>
#include <assert.h>
#include "conf.h"
#include "syslogd-types.h"
#include "cfsysline.h"
#include "module-template.h"

#include <net-snmp/net-snmp-config.h>
#include <net-snmp/net-snmp-includes.h>
#include "omsnmp.h"
#include "errmsg.h"

MODULE_TYPE_OUTPUT

/* internal structures
 */
DEF_OMOD_STATIC_DATA
DEFobjCurrIf(errmsg)

/* Default static snmp OID's */
/*unused 
static oid             objid_enterprise[] = { 1, 3, 6, 1, 4, 1, 3, 1, 1 };
static oid             objid_sysdescr[] = { 1, 3, 6, 1, 2, 1, 1, 1, 0 };
*/
static oid             objid_snmptrap[] = { 1, 3, 6, 1, 6, 3, 1, 1, 4, 1, 0 };
static oid             objid_sysuptime[] = { 1, 3, 6, 1, 2, 1, 1, 3, 0 };

static uchar* pszTransport = NULL; /* default transport */
static uchar* pszTarget = NULL;
/* note using an unsigned for a port number is not a good idea from an IPv6 point of view */
static int iPort = 0;
static int iSNMPVersion = 1;	/* 0 Means SNMPv1, 1 Means SNMPv2c */
static uchar* pszCommunity = NULL;
static uchar* pszEnterpriseOID = NULL;
static uchar* pszSnmpTrapOID = NULL;
static uchar* pszSyslogMessageOID = NULL;
static int iSpecificType = 0;
static int iTrapType = SNMP_TRAP_ENTERPRISESPECIFIC;/*Default is SNMP_TRAP_ENTERPRISESPECIFIC */
/* 
			Possible Values
	SNMP_TRAP_COLDSTART		(0)
	SNMP_TRAP_WARMSTART		(1)
	SNMP_TRAP_LINKDOWN		(2)
	SNMP_TRAP_LINKUP		(3)
	SNMP_TRAP_AUTHFAIL		(4)
	SNMP_TRAP_EGPNEIGHBORLOSS	(5)
	SNMP_TRAP_ENTERPRISESPECIFIC	(6)
*/

typedef struct _instanceData {
	uchar	szTransport[OMSNMP_MAXTRANSPORLENGTH+1];	/* Transport - Can be udp, tcp, udp6, tcp6 and other types supported by NET-SNMP */ 
	uchar	*szTarget;					/* IP/hostname of Snmp Target*/ 
	uchar	*szTargetAndPort;				/* IP/hostname + Port,needed format for SNMP LIB */ 
	uchar	szCommunity[OMSNMP_MAXCOMMUNITYLENGHT+1];	/* Snmp Community */ 
	uchar	szEnterpriseOID[OMSNMP_MAXOIDLENGHT+1];		/* Snmp Enterprise OID - default is (1.3.6.1.4.1.3.1.1 = enterprises.cmu.1.1) */ 
	uchar	szSnmpTrapOID[OMSNMP_MAXOIDLENGHT+1];		/* Snmp Trap OID - default is (1.3.6.1.4.1.19406.1.2.1 = ADISCON-MONITORWARE-MIB::syslogtrap) */ 
	uchar	szSyslogMessageOID[OMSNMP_MAXOIDLENGHT+1];	/* Snmp OID used for the Syslog Message:
	        * default is 1.3.6.1.4.1.19406.1.1.2.1 - ADISCON-MONITORWARE-MIB::syslogMsg
		* You will need the ADISCON-MONITORWARE-MIB and ADISCON-MIB mibs installed on the receiver
		* side in order to decode this mib. 
		* Downloads of these mib files can be found here: 
		*	http://www.adiscon.org/download/ADISCON-MONITORWARE-MIB.txt
		*	http://www.adiscon.org/download/ADISCON-MIB.txt
		*/ 
	int iPort;						/* Target Port */
	int iSNMPVersion;					/* SNMP Version to use */
	int iTrapType;						/* Snmp TrapType or GenericType */
	int iSpecificType;					/* Snmp Specific Type */

	netsnmp_session *snmpsession;						/* Holds to SNMP Session, NULL if not initialized */
} instanceData;

BEGINcreateInstance
CODESTARTcreateInstance
ENDcreateInstance


BEGINdbgPrintInstInfo
CODESTARTdbgPrintInstInfo
	dbgprintf("SNMPTransport: %s\n", pData->szTransport);
	dbgprintf("SNMPTarget: %s\n", pData->szTarget);
	dbgprintf("SNMPPort: %d\n", pData->iPort);
	dbgprintf("SNMPTarget+PortStr: %s\n", pData->szTargetAndPort);
	dbgprintf("SNMPVersion (0=v1, 1=v2c): %d\n", pData->iSNMPVersion);
	dbgprintf("Community: %s\n", pData->szCommunity);
	dbgprintf("EnterpriseOID: %s\n", pData->szEnterpriseOID);
	dbgprintf("SnmpTrapOID: %s\n", pData->szSnmpTrapOID);
	dbgprintf("SyslogMessageOID: %s\n", pData->szSyslogMessageOID);
	dbgprintf("TrapType: %d\n", pData->iTrapType);
	dbgprintf("SpecificType: %d\n", pData->iSpecificType);
ENDdbgPrintInstInfo


BEGINisCompatibleWithFeature
CODESTARTisCompatibleWithFeature
	/* we are not compatible with repeated msg reduction feature, so do not allow it */
ENDisCompatibleWithFeature

/* Exit SNMP Session
 * alorbach, 2008-02-12
 */
static rsRetVal omsnmp_exitSession(instanceData *pData)
{
	DEFiRet;

	if(pData->snmpsession != NULL) {
		dbgprintf( "omsnmp_exitSession: Clearing Session to '%s' on Port = '%d'\n", pData->szTarget, pData->iPort);
		snmp_close(pData->snmpsession);
		pData->snmpsession = NULL;
	}

	RETiRet;
}

/* Init SNMP Session
 * alorbach, 2008-02-12
 */
static rsRetVal omsnmp_initSession(instanceData *pData)
{
	DEFiRet;
	netsnmp_session session;
	
	/* should not happen, but if session is not cleared yet - we do it now! */
	if (pData->snmpsession != NULL)
		omsnmp_exitSession(pData);

	dbgprintf( "omsnmp_initSession: ENTER - Target = '%s' on Port = '%d'\n", pData->szTarget, pData->iPort);

	putenv(strdup("POSIXLY_CORRECT=1"));
	
	snmp_sess_init(&session);
	session.version = pData->iSNMPVersion;
	session.callback = NULL; /* NOT NEEDED */
	session.callback_magic = NULL;
	session.peername = (char*) pData->szTargetAndPort;
	
	/* Set SNMP Community */
	if (session.version == SNMP_VERSION_1 || session.version == SNMP_VERSION_2c)
	{	
		session.community = (unsigned char *) pData->szCommunity;
		session.community_len = strlen((char*) pData->szCommunity);
	}

	pData->snmpsession = snmp_open(&session);
	if (pData->snmpsession == NULL) {
		errmsg.LogError(0, RS_RET_SUSPENDED, "omsnmp_initSession: snmp_open to host '%s' on Port '%d' failed\n", pData->szTarget, pData->iPort);
		/* Stay suspended */
		iRet = RS_RET_SUSPENDED;
	}

	RETiRet;
}

static rsRetVal omsnmp_sendsnmp(instanceData *pData, uchar *psz)
{
	DEFiRet;

	netsnmp_pdu    *pdu = NULL;
	oid             enterpriseoid[MAX_OID_LEN];
	size_t          enterpriseoidlen = MAX_OID_LEN;
	oid				oidSyslogMessage[MAX_OID_LEN];
	size_t			oLen = MAX_OID_LEN;
	int             status;
	char            *trap = NULL;
	const char		*strErr = NULL;

	/* Init SNMP Session if necessary */
	if (pData->snmpsession == NULL) {
		CHKiRet(omsnmp_initSession(pData));
	}
	
	/* String should not be NULL */
	ASSERT(psz != NULL);
	dbgprintf( "omsnmp_sendsnmp: ENTER - Syslogmessage = '%s'\n", (char*)psz);

	/* If SNMP Version1 is configured !*/
	if ( pData->snmpsession->version == SNMP_VERSION_1) 
	{
		pdu = snmp_pdu_create(SNMP_MSG_TRAP);

		/* Set enterprise */
		if (!snmp_parse_oid( (char*) pData->szEnterpriseOID, enterpriseoid, &enterpriseoidlen ))
		{
			strErr = snmp_api_errstring(snmp_errno);
			errmsg.LogError(0, RS_RET_DISABLE_ACTION, "omsnmp_sendsnmp: Parsing EnterpriseOID failed '%s' with error '%s' \n", pData->szSyslogMessageOID, strErr);
			
			ABORT_FINALIZE(RS_RET_DISABLE_ACTION);
		}
		pdu->enterprise = (oid *) MALLOC(enterpriseoidlen * sizeof(oid));
		memcpy(pdu->enterprise, enterpriseoid, enterpriseoidlen * sizeof(oid));
		pdu->enterprise_length = enterpriseoidlen;

		/* Set Traptype */
		pdu->trap_type = pData->iTrapType; 
		
		/* Set SpecificType */
		pdu->specific_type = pData->iSpecificType;

		/* Set Updtime */
		pdu->time = get_uptime();
	}
	/* If SNMP Version2c is configured !*/
	else if (pData->snmpsession->version == SNMP_VERSION_2c) 
	{
		long sysuptime;
		char csysuptime[20];
		
		/* Create PDU */
		pdu = snmp_pdu_create(SNMP_MSG_TRAP2);
		
		/* Set uptime */
		sysuptime = get_uptime();
		snprintf( csysuptime, sizeof(csysuptime) , "%ld", sysuptime);
		trap = csysuptime;
		snmp_add_var(pdu, objid_sysuptime, sizeof(objid_sysuptime) / sizeof(oid), 't', trap);

		/* Now set the SyslogMessage Trap OID */
		if ( snmp_add_var(pdu, objid_snmptrap, sizeof(objid_snmptrap) / sizeof(oid), 'o', (char*) pData->szSnmpTrapOID ) != 0)
		{
			strErr = snmp_api_errstring(snmp_errno);
			errmsg.LogError(0, RS_RET_DISABLE_ACTION, "omsnmp_sendsnmp: Adding trap OID failed '%s' with error '%s' \n", pData->szSnmpTrapOID, strErr);
			ABORT_FINALIZE(RS_RET_DISABLE_ACTION);
		}
	}

	/* SET TRAP PARAMETER for SyslogMessage! */
/*	dbgprintf( "omsnmp_sendsnmp: SyslogMessage '%s'\n", psz );*/

	/* First create new OID object */
	if (snmp_parse_oid( (char*) pData->szSyslogMessageOID, oidSyslogMessage, &oLen))
	{
		int iErrCode = snmp_add_var(pdu, oidSyslogMessage, oLen, 's', (char*) psz);
		if (iErrCode)
		{
			const char *str = snmp_api_errstring(iErrCode);
			errmsg.LogError(0, RS_RET_DISABLE_ACTION,  "omsnmp_sendsnmp: Invalid SyslogMessage OID, error code '%d' - '%s'\n", iErrCode, str );
			ABORT_FINALIZE(RS_RET_DISABLE_ACTION);
		}
	}
	else
	{
		strErr = snmp_api_errstring(snmp_errno);
		errmsg.LogError(0, RS_RET_DISABLE_ACTION, "omsnmp_sendsnmp: Parsing SyslogMessageOID failed '%s' with error '%s' \n", pData->szSyslogMessageOID, strErr);

		ABORT_FINALIZE(RS_RET_DISABLE_ACTION);
	}

	/* Send the TRAP */
	status = snmp_send(pData->snmpsession, pdu) == 0;
	if (status)
	{
		/* Debug Output! */
		int iErrorCode = pData->snmpsession->s_snmp_errno;
		errmsg.LogError(0, RS_RET_SUSPENDED,  "omsnmp_sendsnmp: snmp_send failed error '%d', Description='%s'\n", iErrorCode*(-1), api_errors[iErrorCode*(-1)]);

		/* Clear Session */
		omsnmp_exitSession(pData);

		ABORT_FINALIZE(RS_RET_SUSPENDED);
	}

finalize_it:
	if(iRet != RS_RET_OK) {
		if(pdu != NULL) {
			snmp_free_pdu(pdu);
		}
	}

	dbgprintf( "omsnmp_sendsnmp: LEAVE\n");
	RETiRet;
}


BEGINtryResume
CODESTARTtryResume
	iRet = omsnmp_initSession(pData);
ENDtryResume

BEGINdoAction
CODESTARTdoAction
	/* Abort if the STRING is not set, should never happen */
	if (ppString[0] == NULL) {
		ABORT_FINALIZE(RS_RET_INVALID_PARAMS);
	}
	
	/* This will generate and send the SNMP Trap */
	iRet = omsnmp_sendsnmp(pData, ppString[0]);
finalize_it:
ENDdoAction

BEGINfreeInstance
CODESTARTfreeInstance
	/* free snmp Session here */
	omsnmp_exitSession(pData);

	if(pData->szTarget != NULL)
		free(pData->szTarget);
	if(pData->szTargetAndPort != NULL)
		free(pData->szTargetAndPort);

ENDfreeInstance


BEGINparseSelectorAct
	uchar szTargetAndPort[MAXHOSTNAMELEN+128]; /* work buffer for specifying a full target and port string */
CODESTARTparseSelectorAct
CODE_STD_STRING_REQUESTparseSelectorAct(1)
	if(!strncmp((char*) p, ":omsnmp:", sizeof(":omsnmp:") - 1)) {
		p += sizeof(":omsnmp:") - 1; /* eat indicator sequence (-1 because of '\0'!) */
	} else {
		ABORT_FINALIZE(RS_RET_CONFLINE_UNPROCESSED);
	}

	/* ok, if we reach this point, we have something for us */
	if((iRet = createInstance(&pData)) != RS_RET_OK)
		FINALIZE;

	/* Check Transport */
	if (pszTransport == NULL) {
		/* 
		* Default transport is UDP. Other values supported by NETSNMP are possible as well
		 */
		strncpy( (char*) pData->szTransport, "udp", sizeof("udp") );
	} else {
		/* Copy Transport */
		strncpy( (char*) pData->szTransport, (char*) pszTransport, strlen((char*) pszTransport) );
	}

	/* Check Target */
	if (pszTarget == NULL) {
		ABORT_FINALIZE( RS_RET_PARAM_ERROR );
	} else {
		/* Copy Target */
		CHKmalloc(pData->szTarget = (uchar*) strdup((char*)pszTarget));
	}

	/* Copy Community */
	if (pszCommunity == NULL)	/* Failsave */
		strncpy( (char*) pData->szCommunity, "public", sizeof("public") );
	else						/* Copy Target */
		strncpy( (char*) pData->szCommunity, (char*) pszCommunity, strlen((char*) pszCommunity) );

	/* Copy Enterprise OID */
	if (pszEnterpriseOID == NULL)	/* Failsave */
		strncpy( (char*) pData->szEnterpriseOID, "1.3.6.1.4.1.3.1.1", sizeof("1.3.6.1.4.1.3.1.1") );
	else		/* Copy Target */
		strncpy( (char*) pData->szEnterpriseOID, (char*) pszEnterpriseOID, strlen((char*) pszEnterpriseOID) );

	/* Copy SnmpTrap OID */
	if (pszSnmpTrapOID == NULL)	/* Failsave */
		strncpy( (char*) pData->szSnmpTrapOID, "1.3.6.1.4.1.19406.1.2.1", sizeof("1.3.6.1.4.1.19406.1.2.1") );
	else		/* Copy Target */
		strncpy( (char*) pData->szSnmpTrapOID, (char*) pszSnmpTrapOID, strlen((char*) pszSnmpTrapOID) );


	/* Copy SyslogMessage OID */
	if (pszSyslogMessageOID == NULL)	/* Failsave */
		strncpy( (char*) pData->szSyslogMessageOID, "1.3.6.1.4.1.19406.1.1.2.1", sizeof("1.3.6.1.4.1.19406.1.1.2.1") );
	else						/* Copy Target */
		strncpy( (char*) pData->szSyslogMessageOID, (char*) pszSyslogMessageOID, strlen((char*) pszSyslogMessageOID) );

	/* Copy Port */
	if ( iPort == 0)		/* If no Port is set we use the default Port 162 */
		pData->iPort = 162;
	else
		pData->iPort = iPort;
	
	/* Set SNMPVersion */
	if ( iSNMPVersion < 0 || iSNMPVersion > 1)		/* Set default to 1 if out of range */
		pData->iSNMPVersion = 1;
	else
		pData->iSNMPVersion = iSNMPVersion;

	/* Copy SpecificType */
	if ( iSpecificType == 0)		/* If no iSpecificType is set, we use the default 0 */
		pData->iSpecificType = 0;
	else
		pData->iSpecificType = iSpecificType;

	/* Copy TrapType */
	if ( iTrapType < 0 && iTrapType >= 6)		/* Only allow values from 0 to 6 !*/
		pData->iTrapType = SNMP_TRAP_ENTERPRISESPECIFIC;
	else
		pData->iTrapType = iTrapType;

	/* Create string for session peername! */
	snprintf((char*)szTargetAndPort, sizeof(szTargetAndPort), "%s:%s:%d", pData->szTransport, pData->szTarget, pData->iPort);
	CHKmalloc(pData->szTargetAndPort = (uchar*)strdup((char*)szTargetAndPort));
	
	/* Print Debug info */
	dbgprintf("SNMPTransport: %s\n", pData->szTransport);
	dbgprintf("SNMPTarget: %s\n", pData->szTarget);
	dbgprintf("SNMPPort: %d\n", pData->iPort);
	dbgprintf("SNMPTarget+PortStr: %s\n", pData->szTargetAndPort);
	dbgprintf("SNMPVersion (0=v1, 1=v2c): %d\n", pData->iSNMPVersion);
	dbgprintf("Community: %s\n", pData->szCommunity);
	dbgprintf("EnterpriseOID: %s\n", pData->szEnterpriseOID);
	dbgprintf("SnmpTrapOID: %s\n", pData->szSnmpTrapOID);
	dbgprintf("SyslogMessageOID: %s\n", pData->szSyslogMessageOID);
	dbgprintf("TrapType: %d\n", pData->iTrapType);
	dbgprintf("SpecificType: %d\n", pData->iSpecificType);

	/* process template */
	CHKiRet(cflineParseTemplateName(&p, *ppOMSR, 0, OMSR_NO_RQD_TPL_OPTS, (uchar*) "RSYSLOG_TraditionalForwardFormat"));

	/* Init NetSNMP library and read in MIB database */
	init_snmp("rsyslog");

	/* Set some defaults in the NetSNMP library */
	netsnmp_ds_set_int(NETSNMP_DS_LIBRARY_ID, NETSNMP_DS_LIB_DEFAULT_PORT, pData->iPort );

	/* Init Session Pointer */
	pData->snmpsession = NULL;
CODE_STD_FINALIZERparseSelectorAct
ENDparseSelectorAct


/* Reset config variables for this module to default values.
 */
static rsRetVal resetConfigVariables(uchar __attribute__((unused)) *pp, void __attribute__((unused)) *pVal)
{
	DEFiRet;

	if (pszTarget != NULL)
		free(pszTarget);
	pszTarget = NULL;
	
	if (pszCommunity != NULL)
		free(pszCommunity);
	pszCommunity = NULL;
	
	if (pszEnterpriseOID != NULL)
		free(pszEnterpriseOID);
	pszEnterpriseOID = NULL;

	if (pszSnmpTrapOID != NULL)
		free(pszSnmpTrapOID);
	pszSnmpTrapOID = NULL;

	if (pszSyslogMessageOID != NULL)
		free(pszSyslogMessageOID);
	pszSyslogMessageOID = NULL;

	iPort = 0;
	iSNMPVersion = 1;
	iSpecificType = 0;
	iTrapType = SNMP_TRAP_ENTERPRISESPECIFIC;

	RETiRet;
}


BEGINmodExit
CODESTARTmodExit
	if (pszTarget != NULL)
		free(pszTarget);	
	if (pszCommunity != NULL)
		free(pszCommunity);
	if (pszEnterpriseOID != NULL)
		free(pszEnterpriseOID);
	if (pszSnmpTrapOID != NULL)
		free(pszSnmpTrapOID);
	if (pszSyslogMessageOID != NULL)
		free(pszSyslogMessageOID);

	/* release what we no longer need */
	objRelease(errmsg, CORE_COMPONENT);
ENDmodExit


BEGINqueryEtryPt
CODESTARTqueryEtryPt
CODEqueryEtryPt_STD_OMOD_QUERIES
ENDqueryEtryPt


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

	CHKiRet(omsdRegCFSLineHdlr(	(uchar *)"actionsnmptransport", 0, eCmdHdlrGetWord, NULL, &pszTransport, STD_LOADABLE_MODULE_ID));
	CHKiRet(omsdRegCFSLineHdlr(	(uchar *)"actionsnmptarget", 0, eCmdHdlrGetWord, NULL, &pszTarget, STD_LOADABLE_MODULE_ID));
	CHKiRet(omsdRegCFSLineHdlr(	(uchar *)"actionsnmptargetport", 0, eCmdHdlrInt, NULL, &iPort, STD_LOADABLE_MODULE_ID));
	CHKiRet(omsdRegCFSLineHdlr(	(uchar *)"actionsnmpversion", 0, eCmdHdlrInt, NULL, &iSNMPVersion, STD_LOADABLE_MODULE_ID));
	CHKiRet(omsdRegCFSLineHdlr(	(uchar *)"actionsnmpcommunity", 0, eCmdHdlrGetWord, NULL, &pszCommunity, STD_LOADABLE_MODULE_ID));
	CHKiRet(omsdRegCFSLineHdlr(	(uchar *)"actionsnmpenterpriseoid", 0, eCmdHdlrGetWord, NULL, &pszEnterpriseOID, STD_LOADABLE_MODULE_ID));
	CHKiRet(omsdRegCFSLineHdlr(	(uchar *)"actionsnmptrapoid", 0, eCmdHdlrGetWord, NULL, &pszSnmpTrapOID, STD_LOADABLE_MODULE_ID));
	CHKiRet(omsdRegCFSLineHdlr(	(uchar *)"actionsnmpsyslogmessageoid", 0, eCmdHdlrGetWord, NULL, &pszSyslogMessageOID, STD_LOADABLE_MODULE_ID));
	CHKiRet(omsdRegCFSLineHdlr(	(uchar *)"actionsnmpspecifictype", 0, eCmdHdlrInt, NULL, &iSpecificType, STD_LOADABLE_MODULE_ID));
	CHKiRet(omsdRegCFSLineHdlr(	(uchar *)"actionsnmptraptype", 0, eCmdHdlrInt, NULL, &iTrapType, STD_LOADABLE_MODULE_ID));
	CHKiRet(omsdRegCFSLineHdlr(	(uchar *)"resetconfigvariables", 1, eCmdHdlrCustomHandler, resetConfigVariables, NULL, STD_LOADABLE_MODULE_ID));
ENDmodInit
/*
 * vi:set ai:
 */