path: root/plugins/ommail/ommail.c

/* ommail.c
 *
 * This is an implementation of a mail sending output module. So far, we
 * only support direct SMTP, that is talking to a SMTP server. In the long
 * term, support for using sendmail should also be implemented. Please note
 * that the SMTP protocol implementation is a very bare one. We support 
 * RFC821/822 messages, without any authentication and any other nice
 * features (no MIME, no nothing). It is assumed that proper firewalling
 * and/or STMP server configuration is used together with this module.
 *
 * NOTE: read comments in module-template.h to understand how this file
 *       works!
 *
 * File begun on 2008-04-04 by RGerhards
 *
 * Copyright 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 <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 <assert.h>
#include <unistd.h>
#include <errno.h>
#include <netdb.h>
#include <time.h>
#include <sys/socket.h>
#include "syslogd.h"
#include "syslogd-types.h"
#include "srUtils.h"
#include "cfsysline.h"
#include "module-template.h"
#include "errmsg.h"

MODULE_TYPE_OUTPUT

/* internal structures
 */
DEF_OMOD_STATIC_DATA
DEFobjCurrIf(errmsg)

static uchar *pszSrv = NULL;
static uchar *pszSrvPort = NULL;
static uchar *pszFrom = NULL;
static uchar *pszTo = NULL;
static uchar *pszSubject = NULL;
static int bEnableBody = 1; /* should a mail body be generated? (set to 0 eg for SMS gateways) */

typedef struct _instanceData {
	int iMode;	/* 0 - smtp, 1 - sendmail */
	int bHaveSubject; /* is a subject configured? (if so, it is the second string provided by rsyslog core) */
	int bEnableBody; /* is a body configured? (if so, it is the second string provided by rsyslog core) */
	union {
		struct {
			uchar *pszSrv;
			uchar *pszSrvPort;
			uchar *pszFrom;
			uchar *pszTo;
			char RcvBuf[1024]; /* buffer for receiving server responses */
			size_t lenRcvBuf;
			size_t iRcvBuf;	/* current index into the rcvBuf (buf empty if iRcvBuf == lenRcvBuf) */
			int sock;	/* socket to this server (most important when we do multiple msgs per mail) */
			} smtp;
	} md;	/* mode-specific data */
} instanceData;


BEGINcreateInstance
CODESTARTcreateInstance
ENDcreateInstance


BEGINisCompatibleWithFeature
CODESTARTisCompatibleWithFeature
	if(eFeat == sFEATURERepeatedMsgReduction)
		iRet = RS_RET_OK;
ENDisCompatibleWithFeature


BEGINfreeInstance
CODESTARTfreeInstance
	if(pData->iMode == 0) {
		if(pData->md.smtp.pszSrv != NULL)
			free(pData->md.smtp.pszSrv);
		if(pData->md.smtp.pszSrvPort != NULL)
			free(pData->md.smtp.pszSrvPort);
		if(pData->md.smtp.pszFrom != NULL)
			free(pData->md.smtp.pszFrom);
		if(pData->md.smtp.pszTo != NULL)
			free(pData->md.smtp.pszTo);
	}
ENDfreeInstance


BEGINdbgPrintInstInfo
CODESTARTdbgPrintInstInfo
	printf("mail"); /* TODO: extend! */
ENDdbgPrintInstInfo


/* TCP support code, should probably be moved to net.c or some place else... -- rgerhards, 2008-04-04 */

/* "receive" a character from the remote server. A single character
 * is returned. Returns RS_RET_NO_MORE_DATA if the server has closed
 * the connection and RS_RET_IO_ERROR if something goes wrong. This
 * is a blocking read.
 * rgerhards, 2008-04-04
 */
static rsRetVal
getRcvChar(instanceData *pData, char *pC)
{
	DEFiRet;
	ssize_t lenBuf;
	assert(pData != NULL);

	if(pData->md.smtp.iRcvBuf == pData->md.smtp.lenRcvBuf) { /* buffer empty? */
		/* yes, we need to read the next server response */
		do {
			lenBuf = recv(pData->md.smtp.sock, pData->md.smtp.RcvBuf, sizeof(pData->md.smtp.RcvBuf), 0);
			if(lenBuf == 0) {
				ABORT_FINALIZE(RS_RET_NO_MORE_DATA);
			} else if(lenBuf < 0) {
				if(errno != EAGAIN) {
					ABORT_FINALIZE(RS_RET_IO_ERROR);
				}
			} else {
				/* good read */
				pData->md.smtp.iRcvBuf = 0;
				pData->md.smtp.lenRcvBuf = lenBuf;
			}
				
		} while(lenBuf < 1);
	}

	/* when we reach this point, we have a non-empty buffer */
	*pC = pData->md.smtp.RcvBuf[pData->md.smtp.iRcvBuf++];

finalize_it:
	RETiRet;
}


/* close the mail server connection
 * rgerhards, 2008-04-08
 */
static rsRetVal
serverDisconnect(instanceData *pData)
{
	DEFiRet;
	assert(pData != NULL);

	if(pData->md.smtp.sock != -1) {
		close(pData->md.smtp.sock);
		pData->md.smtp.sock = -1;
	}

	RETiRet;
}


/* open a connection to the mail server
 * rgerhards, 2008-04-04
 */
static rsRetVal
serverConnect(instanceData *pData)
{
	struct addrinfo *res = NULL;
	struct addrinfo hints;
	char *smtpPort;
	char *smtpSrv;
	char errStr[1024];

	DEFiRet;
	assert(pData != NULL);

	if(pData->md.smtp.pszSrv == NULL)
		smtpSrv = "127.0.0.1";
	else
		smtpSrv = (char*)pData->md.smtp.pszSrv;

	if(pData->md.smtp.pszSrvPort == NULL)
		smtpPort = "25";
	else
		smtpPort = (char*)pData->md.smtp.pszSrvPort;

	memset(&hints, 0, sizeof(hints));
	hints.ai_family = AF_UNSPEC; /* TODO: make configurable! */
	hints.ai_socktype = SOCK_STREAM;
	if(getaddrinfo(smtpSrv, smtpPort, &hints, &res) != 0) {
		dbgprintf("error %d in getaddrinfo\n", errno);
		ABORT_FINALIZE(RS_RET_IO_ERROR);
	}
	
	if((pData->md.smtp.sock = socket(res->ai_family, res->ai_socktype, res->ai_protocol)) == -1) {
		dbgprintf("couldn't create send socket, reason %s", rs_strerror_r(errno, errStr, sizeof(errStr)));
		ABORT_FINALIZE(RS_RET_IO_ERROR);
	}

	if(connect(pData->md.smtp.sock, res->ai_addr, res->ai_addrlen) != 0) {
		dbgprintf("create tcp connection failed, reason %s", rs_strerror_r(errno, errStr, sizeof(errStr)));
		ABORT_FINALIZE(RS_RET_IO_ERROR);
	}

finalize_it:
	if(res != NULL)
               freeaddrinfo(res);
		
	if(iRet != RS_RET_OK) {
		if(pData->md.smtp.sock != -1) {
			close(pData->md.smtp.sock);
			pData->md.smtp.sock = -1;
		}
	}

	RETiRet;
}


/* send text to the server, blocking send */
static rsRetVal
Send(int sock, char *msg, size_t len)
{
	DEFiRet;
	size_t offsBuf = 0;
	ssize_t lenSend;

	assert(msg != NULL);

	if(len == 0) /* it's valid, but does not make much sense ;) */
		FINALIZE;

	do {
		lenSend = send(sock, msg + offsBuf, len - offsBuf, 0);
		if(lenSend == -1) {
			if(errno != EAGAIN) {
				dbgprintf("message not (tcp)send, errno %d", errno);
				ABORT_FINALIZE(RS_RET_TCP_SEND_ERROR);
			}
		} else if(lenSend != (ssize_t) len) {
			offsBuf += len; /* on to next round... */
		} else {
			FINALIZE;
		}
	} while(1);

finalize_it:
	RETiRet;
}


/* send body text to the server, blocking send
 * The body is special in that we must escape a leading dot inside a line
 */
static rsRetVal
bodySend(instanceData *pData, char *msg, size_t len)
{
	DEFiRet;
	char szBuf[2048];
	size_t iSrc;
	size_t iBuf = 0;
	int bHadCR = 0;
	int bInStartOfLine = 1;

	assert(pData != NULL);
	assert(msg != NULL);

	for(iSrc = 0 ; iSrc < len ; ++iSrc) {
		if(iBuf >= sizeof(szBuf) - 1) { /* one is reserved for our extra dot */
			CHKiRet(Send(pData->md.smtp.sock, szBuf, iBuf));
			iBuf = 0;
		}
		szBuf[iBuf++] = msg[iSrc];
		switch(msg[iSrc]) {
			case '\r':
				bHadCR = 1;
				break;
			case '\n':
				if(bHadCR)
					bInStartOfLine = 1;
				bHadCR = 0;
				break;
			case '.':
				if(bInStartOfLine)
					szBuf[iBuf++] = '.'; /* space is always reserved for this! */
				/*FALLTHROUGH*/
			default:
				bInStartOfLine = 0;
				bHadCR = 0;
				break;
		}
	}

	if(iBuf > 0) { /* incomplete buffer to send (the *usual* case)? */
		CHKiRet(Send(pData->md.smtp.sock, szBuf, iBuf));
	}

finalize_it:
	RETiRet;
}


/* read response line from server
 */
static rsRetVal
readResponseLn(instanceData *pData, char *pLn, size_t lenLn)
{
	DEFiRet;
	size_t i = 0;
	char c;
	
	assert(pData != NULL);
	assert(pLn != NULL);
	
	do {
		CHKiRet(getRcvChar(pData, &c));
		if(c == '\n')
			break;
		if(i < (lenLn - 1)) /* if line is too long, we simply discard the rest */
			pLn[i++] = c;
	} while(1);
	pLn[i] = '\0';
	dbgprintf("smtp server response: %s\n", pLn); /* do not remove, this is helpful in troubleshooting SMTP probs! */

finalize_it:
	RETiRet;
}


/* read numerical response code from server and compare it to requried response code.
 * If they two don't match, return RS_RET_SMTP_ERROR.
 * rgerhards, 2008-04-07
 */
static rsRetVal
readResponse(instanceData *pData, int *piState, int iExpected)
{
	DEFiRet;
	int bCont;
	char buf[128];
	
	assert(pData != NULL);
	assert(piState != NULL);
	
	bCont = 1;
	do {
		CHKiRet(readResponseLn(pData, buf, sizeof(buf)));
		/* note: the code below is not 100% clean as we may have received less than 4 characters.
		 * However, as we have a fixed size this will not create a vulnerability. An error will
		 * also most likely be generated, so it is quite acceptable IMHO -- rgerhards, 2008-04-08
		 */
		if(buf[3] != '-') { /* last or only response line? */
			bCont = 0;
			*piState = buf[0] - '0';
			*piState = *piState * 10 + buf[1] - '0';
			*piState = *piState * 10 + buf[2] - '0';
			if(*piState != iExpected)
				ABORT_FINALIZE(RS_RET_SMTP_ERROR);
		}
	} while(bCont);
	
finalize_it:
	RETiRet;
}


/* create a timestamp suitable for use with the Date: SMTP body header
 * rgerhards, 2008-04-08
 */
static void
mkSMTPTimestamp(uchar *pszBuf, size_t lenBuf)
{
	time_t tCurr;
	struct tm tmCurr;
	static const char szDay[][4] = {"Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"};
	static const char szMonth[][4] = {"Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"};

	time(&tCurr);
	gmtime_r(&tCurr, &tmCurr);
	snprintf((char*)pszBuf, lenBuf, "Date: %s, %2d %s %4d %2d:%02d:%02d UT\r\n", szDay[tmCurr.tm_wday], tmCurr.tm_mday,
		 szMonth[tmCurr.tm_mon], 1900 + tmCurr.tm_year, tmCurr.tm_hour, tmCurr.tm_min, tmCurr.tm_sec);
}


/* send a message via SMTP
 * rgerhards, 2008-04-04
 */
static rsRetVal
sendSMTP(instanceData *pData, uchar *body, uchar *subject)
{
	DEFiRet;
	int iState; /* SMTP state */
	uchar szDateBuf[64];
	
	assert(pData != NULL);

	CHKiRet(serverConnect(pData));
	CHKiRet(readResponse(pData, &iState, 220));

	CHKiRet(Send(pData->md.smtp.sock, "HELO ", 5));
	CHKiRet(Send(pData->md.smtp.sock, (char*)LocalHostName, strlen((char*)LocalHostName)));
	CHKiRet(Send(pData->md.smtp.sock, "\r\n", sizeof("\r\n") - 1));
	CHKiRet(readResponse(pData, &iState, 250));

	CHKiRet(Send(pData->md.smtp.sock, "MAIL FROM: <", sizeof("MAIL FROM: <") - 1));
	CHKiRet(Send(pData->md.smtp.sock, (char*)pData->md.smtp.pszFrom, strlen((char*)pData->md.smtp.pszFrom)));
	CHKiRet(Send(pData->md.smtp.sock, ">\r\n", sizeof(">\r\n") - 1));
	CHKiRet(readResponse(pData, &iState, 250));

	CHKiRet(Send(pData->md.smtp.sock, "RCPT TO: <",   sizeof("RCPT TO: <") - 1));
	CHKiRet(Send(pData->md.smtp.sock, (char*)pData->md.smtp.pszTo, strlen((char*)pData->md.smtp.pszTo)));
	CHKiRet(Send(pData->md.smtp.sock, ">\r\n", sizeof(">\r\n") - 1));
	CHKiRet(readResponse(pData, &iState, 250));

	CHKiRet(Send(pData->md.smtp.sock, "DATA\r\n",   sizeof("DATA\r\n") - 1));
	CHKiRet(readResponse(pData, &iState, 354));

	/* now come the data part */
	/* header */
	mkSMTPTimestamp(szDateBuf, sizeof(szDateBuf));
	CHKiRet(Send(pData->md.smtp.sock, (char*)szDateBuf, strlen((char*)szDateBuf)));

	CHKiRet(Send(pData->md.smtp.sock, "From: <", sizeof("From: <") - 1));
	CHKiRet(Send(pData->md.smtp.sock, (char*)pData->md.smtp.pszFrom, strlen((char*)pData->md.smtp.pszFrom)));
	CHKiRet(Send(pData->md.smtp.sock, ">\r\n", sizeof(">\r\n") - 1));

	CHKiRet(Send(pData->md.smtp.sock, "To: <",   sizeof("To: <") - 1));
	CHKiRet(Send(pData->md.smtp.sock, (char*)pData->md.smtp.pszTo, strlen((char*)pData->md.smtp.pszTo)));
	CHKiRet(Send(pData->md.smtp.sock, ">\r\n", sizeof(">\r\n") - 1));

	CHKiRet(Send(pData->md.smtp.sock, "Subject: ",   sizeof("Subject: ") - 1));
	CHKiRet(Send(pData->md.smtp.sock, (char*)subject, strlen((char*)subject)));
	CHKiRet(Send(pData->md.smtp.sock, "\r\n", sizeof("\r\n") - 1));

	CHKiRet(Send(pData->md.smtp.sock, "X-Mailer: rsyslog-immail\r\n",   sizeof("x-mailer: rsyslog-immail\r\n") - 1));

	CHKiRet(Send(pData->md.smtp.sock, "\r\n",   sizeof("\r\n") - 1)); /* indicate end of header */

	/* body */
	if(pData->bEnableBody)
		CHKiRet(bodySend(pData, (char*)body, strlen((char*) body)));

	/* end of data, back to envelope transaction */
	CHKiRet(Send(pData->md.smtp.sock, "\r\n.\r\n",   sizeof("\r\n.\r\n") - 1));
	CHKiRet(readResponse(pData, &iState, 250));

	CHKiRet(Send(pData->md.smtp.sock, "QUIT\r\n",   sizeof("QUIT\r\n") - 1));
	CHKiRet(readResponse(pData, &iState, 221));

	/* we are finished, a new connection is created for each request, so let's close it now */
	CHKiRet(serverDisconnect(pData));
	
finalize_it:
	RETiRet;
}


/* in tryResume we check if we can connect to the server in question. If that is OK,
 * we close the connection without doing any actual SMTP transaction. It will be
 * reopened during the actual send process. This may not be the best way to do it if
 * there is a problem inside the SMTP transaction. However, we can't find that out without
 * actually initiating something, and that would be bad. The logic here helps us
 * correctly recover from an unreachable/down mail server, which is probably the majority
 * of problem cases. For SMTP transaction problems, we will do lots of retries, but if it
 * is a temporary problem, it will be fixed anyhow. So I consider this implementation to
 * be clean enough, especially as I think other approaches have other weaknesses.
 * rgerhards, 2008-04-08
 */
BEGINtryResume
CODESTARTtryResume
	CHKiRet(serverConnect(pData));
	CHKiRet(serverDisconnect(pData)); /* if we fail, we will never reach this line */
finalize_it:
	if(iRet == RS_RET_IO_ERROR)
		iRet = RS_RET_SUSPENDED;
ENDtryResume


BEGINdoAction
CODESTARTdoAction
	dbgprintf(" Mail\n");

	/* forward */
	if(pData->bHaveSubject)
		iRet = sendSMTP(pData, ppString[0], ppString[1]);
	else 
		iRet = sendSMTP(pData, ppString[0], (uchar*)"message from rsyslog");
		
	if(iRet != RS_RET_OK) {
		/* error! */
		dbgprintf("error sending mail, suspending\n");
		iRet = RS_RET_SUSPENDED;
	}
ENDdoAction


BEGINparseSelectorAct
CODESTARTparseSelectorAct
	if(!strncmp((char*) p, ":ommail:", sizeof(":ommail:") - 1)) {
		p += sizeof(":ommail:") - 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;

	/* TODO: check strdup() result */

	if(pszFrom == NULL) {
		errmsg.LogError(NO_ERRCODE, "no sender address given - specify $ActionMailFrom");
		ABORT_FINALIZE(RS_RET_MAIL_NO_FROM);
	}
	if(pszTo == NULL) {
		errmsg.LogError(NO_ERRCODE, "no recipient address given - specify $ActionMailTo");
		ABORT_FINALIZE(RS_RET_MAIL_NO_TO);
	}

	pData->md.smtp.pszFrom = (uchar*) strdup((char*)pszFrom);
	pData->md.smtp.pszTo = (uchar*) strdup((char*)pszTo);

	if(pszSubject == NULL) {
		/* if no subject is configured, we need just one template string */
		CODE_STD_STRING_REQUESTparseSelectorAct(1)
	} else {
		CODE_STD_STRING_REQUESTparseSelectorAct(2)
		pData->bHaveSubject = 1;
		CHKiRet(OMSRsetEntry(*ppOMSR, 1, (uchar*)strdup((char*) pszSubject), OMSR_NO_RQD_TPL_OPTS));
	}
	if(pszSrv != NULL)
		pData->md.smtp.pszSrv = (uchar*) strdup((char*)pszSrv);
	if(pszSrvPort != NULL)
		pData->md.smtp.pszSrvPort = (uchar*) strdup((char*)pszSrvPort);
	pData->bEnableBody = bEnableBody;

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


/* Free string config variables and reset them to NULL (not necessarily the default!) */
static rsRetVal freeConfigVariables(void)
{
	DEFiRet;

	if(pszSrv != NULL) {
		free(pszSrv);
		pszSrv = NULL;
	}
	if(pszSrvPort != NULL) {
		free(pszSrvPort);
		pszSrvPort = NULL;
	}
	if(pszFrom != NULL) {
		free(pszFrom);
		pszFrom = NULL;
	}
	if(pszTo != NULL) {
		free(pszTo);
		pszTo = NULL;
	}
	
	RETiRet;
}


BEGINmodExit
CODESTARTmodExit
	/* cleanup our allocations */
	freeConfigVariables();

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


BEGINqueryEtryPt
CODESTARTqueryEtryPt
CODEqueryEtryPt_STD_OMOD_QUERIES
ENDqueryEtryPt


/* Reset config variables for this module to default values.
 */
static rsRetVal resetConfigVariables(uchar __attribute__((unused)) *pp, void __attribute__((unused)) *pVal)
{
	DEFiRet;
	bEnableBody = 1;
	iRet = freeConfigVariables();
	RETiRet;
}


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

	CHKiRet(omsdRegCFSLineHdlr(	(uchar *)"actionmailsmtpserver", 0, eCmdHdlrGetWord, NULL, &pszSrv, STD_LOADABLE_MODULE_ID));
	CHKiRet(omsdRegCFSLineHdlr(	(uchar *)"actionmailsmtpport", 0, eCmdHdlrGetWord, NULL, &pszSrvPort, STD_LOADABLE_MODULE_ID));
	CHKiRet(omsdRegCFSLineHdlr(	(uchar *)"actionmailfrom", 0, eCmdHdlrGetWord, NULL, &pszFrom, STD_LOADABLE_MODULE_ID));
	CHKiRet(omsdRegCFSLineHdlr(	(uchar *)"actionmailto", 0, eCmdHdlrGetWord, NULL, &pszTo, STD_LOADABLE_MODULE_ID));
	CHKiRet(omsdRegCFSLineHdlr(	(uchar *)"actionmailsubject", 0, eCmdHdlrGetWord, NULL, &pszSubject, STD_LOADABLE_MODULE_ID));
	CHKiRet(omsdRegCFSLineHdlr(	(uchar *)"actionmailenablebody", 0, eCmdHdlrBinary, NULL, &bEnableBody, STD_LOADABLE_MODULE_ID));
	CHKiRet(omsdRegCFSLineHdlr(	(uchar *)"resetconfigvariables", 1, eCmdHdlrCustomHandler, resetConfigVariables, NULL, STD_LOADABLE_MODULE_ID));
ENDmodInit

/* vim:set ai:
 */