/* nsd_ossl.c
 *
 * An implementation of the nsd interface for OpenSSL.
 *
 * Copyright 2018-2023 Adiscon GmbH.
 * Author: Andre Lorbach
 *
 * 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 <stdio.h>
#include <stdlib.h>
#include <assert.h>
#include <string.h>
#include <strings.h>

#include <errno.h>
#include <sys/stat.h>
#include <unistd.h>
#include <fcntl.h>
#include <pthread.h>

#include "rsyslog.h"
#include "syslogd-types.h"
#include "module-template.h"
#include "cfsysline.h"
#include "obj.h"
#include "stringbuf.h"
#include "errmsg.h"
#include "net.h"
#include "netstrm.h"
#include "netstrms.h"
#include "datetime.h"
#include "net_ossl.h"	// Include OpenSSL Helpers
#include "nsd_ptcp.h"
#include "nsdsel_ossl.h"
#include "nsd_ossl.h"
#include "unicode-helper.h"
#include "rsconf.h"

MODULE_TYPE_LIB
MODULE_TYPE_KEEP

/* static data */
DEFobjStaticHelpers
DEFobjCurrIf(glbl)
DEFobjCurrIf(net)
DEFobjCurrIf(datetime)
DEFobjCurrIf(nsd_ptcp)
DEFobjCurrIf(net_ossl)

/* Some prototypes for helper functions used inside openssl driver */
static rsRetVal applyGnutlsPriorityString(nsd_ossl_t *const pNsd);

/*--------------------------------------OpenSSL helpers ------------------------------------------*/
void nsd_ossl_lastOpenSSLErrorMsg(nsd_ossl_t const *pThis, const int ret, SSL *ssl, int severity,
	const char* pszCallSource, const char* pszOsslApi)
{
	uchar *fromHost = NULL;
	int errno_store = errno;

	if(pThis != NULL) {
		nsd_ptcp.GetRemoteHName((nsd_t*)pThis->pTcp, &fromHost);
	}

	// Call helper in net_ossl
	net_ossl_lastOpenSSLErrorMsg(fromHost, ret, ssl, severity, pszCallSource, pszOsslApi);

	free(fromHost);
	errno = errno_store;
}

#if OPENSSL_VERSION_NUMBER >= 0x30000000L && !defined(LIBRESSL_VERSION_NUMBER)
long BIO_debug_callback_ex(BIO *bio, int cmd, const char __attribute__((unused)) *argp,
			   size_t __attribute__((unused)) len, int argi, long __attribute__((unused)) argl,
			   int ret, size_t __attribute__((unused)) *processed)
#else
long BIO_debug_callback(BIO *bio, int cmd, const char __attribute__((unused)) *argp,
			int argi, long __attribute__((unused)) argl, long ret)
#endif
{
	long ret2 = ret; // Helper value to avoid printf compile errors long<>int
	long r = 1;
	if (BIO_CB_RETURN & cmd)
		r = ret;
	dbgprintf("openssl debugmsg: BIO[%p]: ", (void *)bio);
	switch (cmd) {
	case BIO_CB_FREE:
		dbgprintf("Free - %s\n", RSYSLOG_BIO_method_name(bio));
		break;
/* Disabled due API changes for OpenSSL 1.1.0+ */
#if OPENSSL_VERSION_NUMBER < 0x10100000L
	case BIO_CB_READ:
		if (bio->method->type & BIO_TYPE_DESCRIPTOR)
			dbgprintf("read(%d,%lu) - %s fd=%d\n",
				RSYSLOG_BIO_number_read(bio), (unsigned long)argi,
				RSYSLOG_BIO_method_name(bio), RSYSLOG_BIO_number_read(bio));
		else
			dbgprintf("read(%d,%lu) - %s\n", RSYSLOG_BIO_number_read(bio),
					(unsigned long)argi, RSYSLOG_BIO_method_name(bio));
		break;
	case BIO_CB_WRITE:
		if (bio->method->type & BIO_TYPE_DESCRIPTOR)
			dbgprintf("write(%d,%lu) - %s fd=%d\n",
				RSYSLOG_BIO_number_written(bio), (unsigned long)argi,
				RSYSLOG_BIO_method_name(bio), RSYSLOG_BIO_number_written(bio));
		else
			dbgprintf("write(%d,%lu) - %s\n",
					RSYSLOG_BIO_number_written(bio),
					(unsigned long)argi,
					RSYSLOG_BIO_method_name(bio));
		break;
#else
	case BIO_CB_READ:
		dbgprintf("read %s\n", RSYSLOG_BIO_method_name(bio));
		break;
	case BIO_CB_WRITE:
		dbgprintf("write %s\n", RSYSLOG_BIO_method_name(bio));
		break;
#endif
	case BIO_CB_PUTS:
		dbgprintf("puts() - %s\n", RSYSLOG_BIO_method_name(bio));
		break;
	case BIO_CB_GETS:
		dbgprintf("gets(%lu) - %s\n", (unsigned long)argi,
			RSYSLOG_BIO_method_name(bio));
		break;
	case BIO_CB_CTRL:
		dbgprintf("ctrl(%lu) - %s\n", (unsigned long)argi,
			RSYSLOG_BIO_method_name(bio));
		break;
	case BIO_CB_RETURN | BIO_CB_READ:
		dbgprintf("read return %ld\n", ret2);
		break;
	case BIO_CB_RETURN | BIO_CB_WRITE:
		dbgprintf("write return %ld\n", ret2);
		break;
	case BIO_CB_RETURN | BIO_CB_GETS:
		dbgprintf("gets return %ld\n", ret2);
		break;
	case BIO_CB_RETURN | BIO_CB_PUTS:
		dbgprintf("puts return %ld\n", ret2);
		break;
	case BIO_CB_RETURN | BIO_CB_CTRL:
		dbgprintf("ctrl return %ld\n", ret2);
		break;
	default:
		dbgprintf("bio callback - unknown type (%d)\n", cmd);
		break;
	}

	return (r);
}

/* try to receive a record from the remote peer. This works with
 * our own abstraction and handles local buffering and EAGAIN.
 * See details on local buffering in Rcv(9 header-comment.
 * This function MUST only be called when the local buffer is
 * empty. Calling it otherwise will cause losss of current buffer
 * data.
 * rgerhards, 2008-06-24
 */
rsRetVal
osslRecordRecv(nsd_ossl_t *pThis)
{
	ssize_t lenRcvd;
	DEFiRet;
	int err;

	ISOBJ_TYPE_assert(pThis, nsd_ossl);
	DBGPRINTF("osslRecordRecv: start\n");

	lenRcvd = SSL_read(pThis->pNetOssl->ssl, pThis->pszRcvBuf, NSD_OSSL_MAX_RCVBUF);
	if(lenRcvd > 0) {
		DBGPRINTF("osslRecordRecv: SSL_read received %zd bytes\n", lenRcvd);
		pThis->lenRcvBuf = lenRcvd;
		pThis->ptrRcvBuf = 0;

		/* Check for additional data in SSL buffer */
		int iBytesLeft = SSL_pending(pThis->pNetOssl->ssl);
		if (iBytesLeft > 0 ){
			DBGPRINTF("osslRecordRecv: %d Bytes pending after SSL_Read, expand buffer.\n", iBytesLeft);
			/* realloc buffer size and preserve char content */
			char *const newbuf = realloc(pThis->pszRcvBuf, NSD_OSSL_MAX_RCVBUF+iBytesLeft);
			CHKmalloc(newbuf);
			pThis->pszRcvBuf = newbuf;

			/* 2nd read will read missing bytes from the current SSL Packet */
			lenRcvd = SSL_read(pThis->pNetOssl->ssl, pThis->pszRcvBuf+NSD_OSSL_MAX_RCVBUF, iBytesLeft);
			if(lenRcvd > 0) {
				DBGPRINTF("osslRecordRecv: 2nd SSL_read received %zd bytes\n",
					(NSD_OSSL_MAX_RCVBUF+lenRcvd));
				pThis->lenRcvBuf = NSD_OSSL_MAX_RCVBUF+lenRcvd;
			} else {
				goto sslerr;
			}
		}
	} else {
sslerr:
		err = SSL_get_error(pThis->pNetOssl->ssl, lenRcvd);
		if(	err == SSL_ERROR_ZERO_RETURN ) {
			DBGPRINTF("osslRecordRecv: SSL_ERROR_ZERO_RETURN received, connection may closed already\n");
			ABORT_FINALIZE(RS_RET_RETRY);
		}
		else if(err == SSL_ERROR_SYSCALL) {
			/* Output error and abort */
			nsd_ossl_lastOpenSSLErrorMsg(pThis, lenRcvd, pThis->pNetOssl->ssl, LOG_INFO,
				"osslRecordRecv", "SSL_read 1");
			iRet = RS_RET_NO_ERRCODE;
			/* Check for underlaying socket errors **/
			if (	errno == ECONNRESET) {
				DBGPRINTF("osslRecordRecv: SSL_ERROR_SYSCALL Errno %d, connection reset by peer\n",
					errno);
				/* Connection was dropped from remote site */
				iRet = RS_RET_CLOSED;
			} else {
				DBGPRINTF("osslRecordRecv: SSL_ERROR_SYSCALL Errno %d\n", errno);
			}
			ABORT_FINALIZE(iRet);
		}
		else if(err != SSL_ERROR_WANT_READ &&
			err != SSL_ERROR_WANT_WRITE) {
			DBGPRINTF("osslRecordRecv: SSL_get_error #1 = %d, lenRcvd=%zd\n", err, lenRcvd);
			/* Output OpenSSL error*/
			nsd_ossl_lastOpenSSLErrorMsg(pThis, lenRcvd, pThis->pNetOssl->ssl, LOG_ERR,
				"osslRecordRecv", "SSL_read 2");
			ABORT_FINALIZE(RS_RET_NO_ERRCODE);
		} else {
			DBGPRINTF("osslRecordRecv: SSL_get_error #2 = %d, lenRcvd=%zd\n", err, lenRcvd);
			pThis->rtryCall =  osslRtry_recv;
			pThis->rtryOsslErr = err; /* Store SSL ErrorCode into*/
			ABORT_FINALIZE(RS_RET_RETRY);
		}
	}

// TODO: Check if MORE retry logic needed?

finalize_it:
	dbgprintf("osslRecordRecv return. nsd %p, iRet %d, lenRcvd %zd, lenRcvBuf %d, ptrRcvBuf %d\n",
	pThis, iRet, lenRcvd, pThis->lenRcvBuf, pThis->ptrRcvBuf);
	RETiRet;
}

static rsRetVal
osslInitSession(nsd_ossl_t *pThis, osslSslState_t osslType) /* , nsd_ossl_t *pServer) */
{
	DEFiRet;
	BIO *conn;
	char pristringBuf[4096];
	nsd_ptcp_t *pPtcp = (nsd_ptcp_t*) pThis->pTcp;

	if(!(pThis->pNetOssl->ssl = SSL_new(pThis->pNetOssl->ctx))) {
		pThis->pNetOssl->ssl = NULL;
		nsd_ossl_lastOpenSSLErrorMsg(pThis, 0, pThis->pNetOssl->ssl, LOG_ERR, "osslInitSession", "SSL_new");
		ABORT_FINALIZE(RS_RET_NO_ERRCODE);
	}

	// Set SSL_MODE_AUTO_RETRY to SSL obj
	SSL_set_mode(pThis->pNetOssl->ssl, SSL_MODE_AUTO_RETRY);

	if (pThis->pNetOssl->authMode != OSSL_AUTH_CERTANON) {
		dbgprintf("osslInitSession: enable certificate checking (Mode=%d, VerifyDepth=%d)\n",
			pThis->pNetOssl->authMode, pThis->DrvrVerifyDepth);
		/* Enable certificate valid checking */
		net_ossl_set_ssl_verify_callback(pThis->pNetOssl->ssl, SSL_VERIFY_PEER|SSL_VERIFY_FAIL_IF_NO_PEER_CERT);
		if (pThis->DrvrVerifyDepth != 0) {
			SSL_set_verify_depth(pThis->pNetOssl->ssl, pThis->DrvrVerifyDepth);
		}
	} else 	if (pThis->gnutlsPriorityString == NULL) {
		/* Allow ANON Ciphers only in ANON Mode and if no custom priority string is defined */
		#if OPENSSL_VERSION_NUMBER >= 0x10100000L && !defined(LIBRESSL_VERSION_NUMBER)
		 /* NOTE: do never use: +eNULL, it DISABLES encryption! */
		strncpy(pristringBuf, "ALL:+COMPLEMENTOFDEFAULT:+ADH:+ECDH:+aNULL@SECLEVEL=0",
			sizeof(pristringBuf));
		#else
		strncpy(pristringBuf, "ALL:+COMPLEMENTOFDEFAULT:+ADH:+ECDH:+aNULL",
			sizeof(pristringBuf));
		#endif

		dbgprintf("osslInitSession: setting anon ciphers: %s\n", pristringBuf);
		if ( SSL_set_cipher_list(pThis->pNetOssl->ssl, pristringBuf) == 0 ){
			dbgprintf("osslInitSession: Error setting ciphers '%s'\n", pristringBuf);
			ABORT_FINALIZE(RS_RET_SYS_ERR);
		}
	}

	/* Create BIO from ptcp socket! */
	conn = BIO_new_socket(pPtcp->sock, BIO_CLOSE /*BIO_NOCLOSE*/);
	dbgprintf("osslInitSession: Init conn BIO[%p] done\n", (void *)conn);

	/* Set debug Callback for conn BIO as well! */
	net_ossl_set_bio_callback(conn);

	/* TODO: still needed? Set to NON blocking ! */
	BIO_set_nbio( conn, 1 );
	SSL_set_bio(pThis->pNetOssl->ssl, conn, conn);

	if (osslType == osslServer) {
		/* Server Socket */
		SSL_set_accept_state(pThis->pNetOssl->ssl); /* sets ssl to work in server mode. */
		pThis->pNetOssl->sslState = osslServer; /*set Server state */
	} else {
		/* Client Socket */
		SSL_set_connect_state(pThis->pNetOssl->ssl); /*sets ssl to work in client mode.*/
		pThis->pNetOssl->sslState = osslClient; /*set Client state */
	}
	pThis->bHaveSess = 1;

	/* we are done */
	FINALIZE;

finalize_it:
	RETiRet;
}


/* check if it is OK to talk to the remote peer
 * rgerhards, 2008-05-21
 */
rsRetVal
osslChkPeerAuth(nsd_ossl_t *pThis)
{
	DEFiRet;
	X509 *certpeer;

	ISOBJ_TYPE_assert(pThis, nsd_ossl);
	uchar *fromHostIP = NULL;
	nsd_ptcp.GetRemoteHName((nsd_t*)pThis->pTcp, &fromHostIP);

	/* call the actual function based on current auth mode */
	switch(pThis->pNetOssl->authMode) {
		case OSSL_AUTH_CERTNAME:
			/* if we check the name, we must ensure the cert is valid */
			certpeer = net_ossl_getpeercert(pThis->pNetOssl, pThis->pNetOssl->ssl, fromHostIP);
			dbgprintf("osslChkPeerAuth: Check peer certname[%p]=%s\n",
				(void *)pThis->pNetOssl->ssl, (certpeer != NULL ? "VALID" : "NULL"));
			CHKiRet(net_ossl_chkpeercertvalidity(pThis->pNetOssl, pThis->pNetOssl->ssl, fromHostIP));
			CHKiRet(net_ossl_chkpeername(pThis->pNetOssl, certpeer, fromHostIP));
			break;
		case OSSL_AUTH_CERTFINGERPRINT:
			certpeer = net_ossl_getpeercert(pThis->pNetOssl, pThis->pNetOssl->ssl, fromHostIP);
			dbgprintf("osslChkPeerAuth: Check peer fingerprint[%p]=%s\n",
				(void *)pThis->pNetOssl->ssl, (certpeer != NULL ? "VALID" : "NULL"));
			CHKiRet(net_ossl_chkpeercertvalidity(pThis->pNetOssl, pThis->pNetOssl->ssl, fromHostIP));
			CHKiRet(net_ossl_peerfingerprint(pThis->pNetOssl, certpeer, fromHostIP));

			break;
		case OSSL_AUTH_CERTVALID:
			certpeer = net_ossl_getpeercert(pThis->pNetOssl, pThis->pNetOssl->ssl, fromHostIP);
			dbgprintf("osslChkPeerAuth: Check peer valid[%p]=%s\n",
				(void *)pThis->pNetOssl->ssl, (certpeer != NULL ? "VALID" : "NULL"));
			CHKiRet(net_ossl_chkpeercertvalidity(pThis->pNetOssl, pThis->pNetOssl->ssl, fromHostIP));
			break;
		case OSSL_AUTH_CERTANON:
			FINALIZE;
			break;
	}
finalize_it:
	if (fromHostIP != NULL) {
		free(fromHostIP);
	}
	RETiRet;
}

/* end a OpenSSL session
 * The function checks if we have a session and ends it only if so. So it can
 * always be called, even if there currently is no session.
 */
static rsRetVal
osslEndSess(nsd_ossl_t *pThis)
{
	DEFiRet;
	uchar *fromHostIP = NULL;
	int ret;
	int err;

	/* try closing SSL Connection */
	if(pThis->bHaveSess) {
		DBGPRINTF("osslEndSess: closing SSL Session ...\n");
		ret = SSL_shutdown(pThis->pNetOssl->ssl);
		nsd_ptcp.GetRemoteHName((nsd_t*)pThis->pTcp, &fromHostIP);
		if (ret <= 0) {
			err = SSL_get_error(pThis->pNetOssl->ssl, ret);
			DBGPRINTF("osslEndSess: shutdown failed with err = %d\n", err);

			/* ignore those SSL Errors on shutdown */
			if(	err != SSL_ERROR_SYSCALL &&
					err != SSL_ERROR_ZERO_RETURN &&
					err != SSL_ERROR_WANT_READ &&
					err != SSL_ERROR_WANT_WRITE) {
				/* Output Warning only */
				nsd_ossl_lastOpenSSLErrorMsg(pThis, ret, pThis->pNetOssl->ssl, LOG_WARNING,
					"osslEndSess", "SSL_shutdown");
			}
			/* Shutdown not finished, call SSL_read to do a bidirectional shutdown, see doc for more:
			*	https://www.openssl.org/docs/man1.1.1/man3/SSL_shutdown.html
			*/
			char rcvBuf[NSD_OSSL_MAX_RCVBUF];
			int iBytesRet = SSL_read(pThis->pNetOssl->ssl, rcvBuf, NSD_OSSL_MAX_RCVBUF);
			DBGPRINTF("osslEndSess: Forcing ssl shutdown SSL_read (%d) to do a bidirectional shutdown\n",
				iBytesRet);
			if (ret < 0) {
				/* Unsuccessful shutdown, log as INFO */
				LogMsg(0, RS_RET_NO_ERRCODE, LOG_INFO, "nsd_ossl: "
				"TLS session terminated successfully to remote syslog server '%s' with SSL Error '%d':"
				" End Session", fromHostIP, ret);
			}
			dbgprintf( "osslEndSess: TLS session terminated successfully to remote syslog server '%s'"
				" End Session", fromHostIP);
		} else {
			dbgprintf("osslEndSess: TLS session terminated successfully with remote syslog server '%s':"
				" End Session", fromHostIP);
		}

		/* Session closed */
		pThis->bHaveSess = 0;
	}

	if (fromHostIP != NULL) {
		free(fromHostIP);
	}
	RETiRet;
}
/* ---------------------------- end OpenSSL specifics ---------------------------- */


/* Standard-Constructor */
BEGINobjConstruct(nsd_ossl) /* be sure to specify the object type also in END macro! */
	/* construct nsd_ptcp helper */
	CHKiRet(nsd_ptcp.Construct(&pThis->pTcp));
	/* construct net_ossl helper */
	CHKiRet(net_ossl.Construct(&pThis->pNetOssl));
finalize_it:
ENDobjConstruct(nsd_ossl)


/* destructor for the nsd_ossl object */
PROTOTYPEobjDestruct(nsd_ossl);
BEGINobjDestruct(nsd_ossl) /* be sure to specify the object type also in END and CODESTART macros! */
CODESTARTobjDestruct(nsd_ossl)
	DBGPRINTF("nsd_ossl_destruct: [%p] Mode %d\n", pThis, pThis->iMode);
	if(pThis->iMode == 1) {
		osslEndSess(pThis);
	}
	/* TODO MOVE Free SSL obj also if we do not have a session - or are NOT in TLS mode! */
	if (pThis->pNetOssl->ssl != NULL) {
		DBGPRINTF("nsd_ossl_destruct: [%p] FREE pThis->pNetOssl->ssl \n", pThis);
		SSL_free(pThis->pNetOssl->ssl);
		pThis->pNetOssl->ssl = NULL;
	}
	/**/
	if(pThis->pTcp != NULL) {
		nsd_ptcp.Destruct(&pThis->pTcp);
	}
	if(pThis->pNetOssl != NULL) {
		net_ossl.Destruct(&pThis->pNetOssl);
	}

	free(pThis->pszConnectHost);
	free(pThis->pszRcvBuf);
ENDobjDestruct(nsd_ossl)


/* Set the driver mode. For us, this has the following meaning:
 * 0 - work in plain tcp mode, without tls (e.g. before a STARTTLS)
 * 1 - work in TLS mode
 * rgerhards, 2008-04-28
 */
static rsRetVal
SetMode(nsd_t *pNsd, const int mode)
{
	DEFiRet;
	nsd_ossl_t *pThis = (nsd_ossl_t*) pNsd;

	ISOBJ_TYPE_assert((pThis), nsd_ossl);
	if(mode != 0 && mode != 1) {
		LogError(0, RS_RET_INVALID_DRVR_MODE, "error: driver mode %d not supported by"
				" ossl netstream driver", mode);
	}
	pThis->iMode = mode;

	RETiRet;
}

/* Set the authentication mode. For us, the following is supported:
 * anon - no certificate checks whatsoever (discouraged, but supported)
 * x509/certvalid - (just) check certificate validity
 * x509/fingerprint - certificate fingerprint
 * x509/name - cerfificate name check
 * mode == NULL is valid and defaults to x509/name
 * rgerhards, 2008-05-16
 */
static rsRetVal
SetAuthMode(nsd_t *const pNsd, uchar *const mode)
{
	DEFiRet;
	nsd_ossl_t *pThis = (nsd_ossl_t*) pNsd;

	ISOBJ_TYPE_assert((pThis), nsd_ossl);
	if(mode == NULL || !strcasecmp((char*)mode, "x509/name")) {
		pThis->pNetOssl->authMode = OSSL_AUTH_CERTNAME;
	} else if(!strcasecmp((char*) mode, "x509/fingerprint")) {
		pThis->pNetOssl->authMode = OSSL_AUTH_CERTFINGERPRINT;
	} else if(!strcasecmp((char*) mode, "x509/certvalid")) {
		pThis->pNetOssl->authMode = OSSL_AUTH_CERTVALID;
	} else if(!strcasecmp((char*) mode, "anon")) {
		pThis->pNetOssl->authMode = OSSL_AUTH_CERTANON;

	} else {
		LogError(0, RS_RET_VALUE_NOT_SUPPORTED, "error: authentication mode '%s' not supported by "
				"ossl netstream driver", mode);
		ABORT_FINALIZE(RS_RET_VALUE_NOT_SUPPORTED);
	}

	dbgprintf("SetAuthMode: Set Mode %s/%d\n", mode, pThis->pNetOssl->authMode);

finalize_it:
	RETiRet;
}


/* Set the PermitExpiredCerts mode. For us, the following is supported:
 * on - fail if certificate is expired
 * off - ignore expired certificates
 * warn - warn if certificate is expired
 * alorbach, 2018-12-20
 */
static rsRetVal
SetPermitExpiredCerts(nsd_t *pNsd, uchar *mode)
{
	DEFiRet;
	nsd_ossl_t *pThis = (nsd_ossl_t*) pNsd;

	ISOBJ_TYPE_assert((pThis), nsd_ossl);
	/* default is set to off! */
	if(mode == NULL || !strcasecmp((char*)mode, "off")) {
		pThis->permitExpiredCerts = OSSL_EXPIRED_DENY;
	} else if(!strcasecmp((char*) mode, "warn")) {
		pThis->permitExpiredCerts = OSSL_EXPIRED_WARN;
	} else if(!strcasecmp((char*) mode, "on")) {
		pThis->permitExpiredCerts = OSSL_EXPIRED_PERMIT;
	} else {
		LogError(0, RS_RET_VALUE_NOT_SUPPORTED, "error: permitexpiredcerts mode '%s' not supported by "
				"ossl netstream driver", mode);
		ABORT_FINALIZE(RS_RET_VALUE_NOT_SUPPORTED);
	}

	dbgprintf("SetPermitExpiredCerts: Set Mode %s/%d\n", mode, pThis->permitExpiredCerts);

/* TODO: clear stored IDs! */

finalize_it:
	RETiRet;
}


/* Set permitted peers. It is depending on the auth mode if this are
 * fingerprints or names. -- rgerhards, 2008-05-19
 */
static rsRetVal
SetPermPeers(nsd_t *pNsd, permittedPeers_t *pPermPeers)
{
	DEFiRet;
	nsd_ossl_t *pThis = (nsd_ossl_t*) pNsd;

	ISOBJ_TYPE_assert((pThis), nsd_ossl);
	if(pPermPeers == NULL)
		FINALIZE;

	if(pThis->pNetOssl->authMode != OSSL_AUTH_CERTFINGERPRINT && pThis->pNetOssl->authMode != OSSL_AUTH_CERTNAME) {
		LogError(0, RS_RET_VALUE_NOT_IN_THIS_MODE, "authentication not supported by "
				"ossl netstream driver in the configured authentication mode - ignored");
		ABORT_FINALIZE(RS_RET_VALUE_NOT_IN_THIS_MODE);
	}
	pThis->pNetOssl->pPermPeers = pPermPeers;

finalize_it:
	RETiRet;
}


/* Provide access to the underlying OS socket. This is primarily
 * useful for other drivers (like nsd_ossl) who utilize ourselfs
 * for some of their functionality. -- rgerhards, 2008-04-18
 */
static rsRetVal
SetSock(nsd_t *pNsd, int sock)
{
	DEFiRet;
	nsd_ossl_t *pThis = (nsd_ossl_t*) pNsd;
	ISOBJ_TYPE_assert((pThis), nsd_ossl);
	assert(sock >= 0);

	DBGPRINTF("SetSock for [%p]: Setting sock %d\n", pNsd, sock);
	nsd_ptcp.SetSock(pThis->pTcp, sock);

	RETiRet;
}


/* Keep Alive Options
 */
static rsRetVal
SetKeepAliveIntvl(nsd_t *pNsd, int keepAliveIntvl)
{
	DEFiRet;
	nsd_ossl_t *pThis = (nsd_ossl_t*) pNsd;

	ISOBJ_TYPE_assert((pThis), nsd_ossl);
	assert(keepAliveIntvl >= 0);

	dbgprintf("SetKeepAliveIntvl: keepAliveIntvl=%d\n", keepAliveIntvl);
	nsd_ptcp.SetKeepAliveIntvl(pThis->pTcp, keepAliveIntvl);

	RETiRet;
}


/* Keep Alive Options
 */
static rsRetVal
SetKeepAliveProbes(nsd_t *pNsd, int keepAliveProbes)
{
	DEFiRet;
	nsd_ossl_t *pThis = (nsd_ossl_t*) pNsd;

	ISOBJ_TYPE_assert((pThis), nsd_ossl);
	assert(keepAliveProbes >= 0);

	dbgprintf("SetKeepAliveProbes: keepAliveProbes=%d\n", keepAliveProbes);
	nsd_ptcp.SetKeepAliveProbes(pThis->pTcp, keepAliveProbes);

	RETiRet;
}


/* Keep Alive Options
 */
static rsRetVal
SetKeepAliveTime(nsd_t *pNsd, int keepAliveTime)
{
	DEFiRet;
	nsd_ossl_t *pThis = (nsd_ossl_t*) pNsd;

	ISOBJ_TYPE_assert((pThis), nsd_ossl);
	assert(keepAliveTime >= 0);

	dbgprintf("SetKeepAliveTime: keepAliveTime=%d\n", keepAliveTime);
	nsd_ptcp.SetKeepAliveTime(pThis->pTcp, keepAliveTime);

	RETiRet;
}


/* abort a connection. This is meant to be called immediately
 * before the Destruct call. -- rgerhards, 2008-03-24
 */
static rsRetVal
Abort(nsd_t *pNsd)
{
	nsd_ossl_t *pThis = (nsd_ossl_t*) pNsd;
	DEFiRet;

	ISOBJ_TYPE_assert((pThis), nsd_ossl);

	if(pThis->iMode == 0) {
		nsd_ptcp.Abort(pThis->pTcp);
	}

	RETiRet;
}


/* Callback after netstrm obj init in nsd_ptcp - permits us to add some data */
static rsRetVal
LstnInitDrvr(netstrm_t *const pThis)
{
	DEFiRet;
	nsd_ossl_t* pNsdOssl = (nsd_ossl_t*) pThis->pDrvrData;
	/* Create main CTX Object. Use SSLv23_method for < Openssl 1.1.0 and TLS_method for all newer versions! */
#if OPENSSL_VERSION_NUMBER < 0x10100000L
	CHKiRet(net_ossl.osslCtxInit(pNsdOssl->pNetOssl, SSLv23_method()));
#else
	CHKiRet(net_ossl.osslCtxInit(pNsdOssl->pNetOssl, TLS_method()));
#endif
	// Apply PriorityString after Ctx Creation
	applyGnutlsPriorityString(pNsdOssl);
finalize_it:
	RETiRet;
}


/* initialize the tcp socket for a listner
 * Here, we use the ptcp driver - because there is nothing special
 * at this point with OpenSSL. Things become special once we accept
 * a session, but not during listener setup.
 */
static rsRetVal
LstnInit(netstrms_t *pNS, void *pUsr, rsRetVal(*fAddLstn)(void*,netstrm_t*),
	 const int iSessMax, const tcpLstnParams_t *const cnf_params)
{
	DEFiRet;

	dbgprintf("LstnInit for openssl: entering LstnInit (%p) for %s:%s SessMax=%d\n",
		fAddLstn, cnf_params->pszAddr, cnf_params->pszPort, iSessMax);

	pNS->fLstnInitDrvr = LstnInitDrvr;
	/* Init TCP Listener using base ptcp class */
	iRet = nsd_ptcp.LstnInit(pNS, pUsr, fAddLstn, iSessMax, cnf_params);
	RETiRet;
}


/* This function checks if the connection is still alive - well, kind of...
 * This is a dummy here. For details, check function common in ptcp driver.
 * rgerhards, 2008-06-09
 */
static rsRetVal
CheckConnection(nsd_t __attribute__((unused)) *pNsd)
{
	nsd_ossl_t *pThis = (nsd_ossl_t*) pNsd;
	ISOBJ_TYPE_assert(pThis, nsd_ossl);

	dbgprintf("CheckConnection for %p\n", pNsd);
	return nsd_ptcp.CheckConnection(pThis->pTcp);
}


/* get the remote hostname. The returned hostname must be freed by the caller.
 * rgerhards, 2008-04-25
 */
static rsRetVal
GetRemoteHName(nsd_t *pNsd, uchar **ppszHName)
{
	DEFiRet;
	nsd_ossl_t *pThis = (nsd_ossl_t*) pNsd;
	ISOBJ_TYPE_assert(pThis, nsd_ossl);
	iRet = nsd_ptcp.GetRemoteHName(pThis->pTcp, ppszHName);
	dbgprintf("GetRemoteHName for %p = %s\n", pNsd, *ppszHName);
	RETiRet;
}


/* Provide access to the sockaddr_storage of the remote peer. This
 * is needed by the legacy ACL system. --- gerhards, 2008-12-01
 */
static rsRetVal
GetRemAddr(nsd_t *pNsd, struct sockaddr_storage **ppAddr)
{
	DEFiRet;
	nsd_ossl_t *pThis = (nsd_ossl_t*) pNsd;
	ISOBJ_TYPE_assert(pThis, nsd_ossl);
	iRet = nsd_ptcp.GetRemAddr(pThis->pTcp, ppAddr);
	dbgprintf("GetRemAddr for %p\n", pNsd);
	RETiRet;
}


/* get the remote host's IP address. Caller must Destruct the object. */
static rsRetVal
GetRemoteIP(nsd_t *pNsd, prop_t **ip)
{
	DEFiRet;
	nsd_ossl_t *pThis = (nsd_ossl_t*) pNsd;
	ISOBJ_TYPE_assert(pThis, nsd_ossl);
	iRet = nsd_ptcp.GetRemoteIP(pThis->pTcp, ip);
	dbgprintf("GetRemoteIP for %p\n", pNsd);
	RETiRet;
}


/* Perform all necessary checks after Handshake
 */
rsRetVal
osslPostHandshakeCheck(nsd_ossl_t *pNsd)
{
	DEFiRet;
	char szDbg[255];
	const SSL_CIPHER* sslCipher;

	/* Some extra output for debugging openssl */
	if (SSL_get_shared_ciphers(pNsd->pNetOssl->ssl,szDbg, sizeof szDbg) != NULL)
		dbgprintf("osslPostHandshakeCheck: Debug Shared ciphers = %s\n", szDbg);

	#if OPENSSL_VERSION_NUMBER >= 0x10002000L
	if(SSL_get_shared_curve(pNsd->pNetOssl->ssl, -1) == 0) {
		// This is not a failure
		LogMsg(0, RS_RET_NO_ERRCODE, LOG_INFO, "nsd_ossl: "
		"Information, no shared curve between syslog client and server");
	}
	#endif
	dbgprintf("osslPostHandshakeCheck: Debug Protocol Version: %s\n",
		SSL_get_version(pNsd->pNetOssl->ssl));

	sslCipher = (const SSL_CIPHER*) SSL_get_current_cipher(pNsd->pNetOssl->ssl);
	if (sslCipher != NULL){
		if(SSL_CIPHER_get_version(sslCipher) == NULL) {
			LogError(0, RS_RET_NO_ERRCODE, "nsd_ossl:"
		"TLS version mismatch between syslog client and server.");
		}
		dbgprintf("osslPostHandshakeCheck: Debug Cipher Version: %s Name: %s\n",
			SSL_CIPHER_get_version(sslCipher), SSL_CIPHER_get_name(sslCipher));
	}else {
		LogError(0, RS_RET_NO_ERRCODE, "nsd_ossl:No shared ciphers between syslog client and server.");
	}

	FINALIZE;

finalize_it:
	RETiRet;
}


/* Perform all necessary actions for Handshake
 */
rsRetVal
osslHandshakeCheck(nsd_ossl_t *pNsd)
{
	DEFiRet;
	uchar *fromHostIP = NULL;
	int res, resErr;
	dbgprintf("osslHandshakeCheck: Starting TLS Handshake for ssl[%p]\n", (void *)pNsd->pNetOssl->ssl);

	if (pNsd->pNetOssl->sslState == osslServer) {
		/* Handle Server SSL Object */
		if((res = SSL_accept(pNsd->pNetOssl->ssl)) <= 0) {
			/* Obtain SSL Error code */
			nsd_ptcp.GetRemoteHName((nsd_t*)pNsd->pTcp, &fromHostIP);
			resErr = SSL_get_error(pNsd->pNetOssl->ssl, res);
			if(	resErr == SSL_ERROR_WANT_READ ||
				resErr == SSL_ERROR_WANT_WRITE) {
				pNsd->rtryCall = osslRtry_handshake;
				pNsd->rtryOsslErr = resErr; /* Store SSL ErrorCode into*/
				dbgprintf("osslHandshakeCheck: OpenSSL Server handshake does not complete "
					"immediately - setting to retry (this is OK and normal)\n");
				FINALIZE;
			} else if(resErr == SSL_ERROR_SYSCALL) {
				dbgprintf("osslHandshakeCheck: OpenSSL Server handshake failed with SSL_ERROR_SYSCALL "
					"- Aborting handshake.\n");
				nsd_ossl_lastOpenSSLErrorMsg(pNsd, res, pNsd->pNetOssl->ssl, LOG_WARNING,
					"osslHandshakeCheck Server", "SSL_accept");
				LogMsg(0, RS_RET_NO_ERRCODE, LOG_WARNING,
					"nsd_ossl:TLS session terminated with remote client '%s': "
					"Handshake failed with SSL_ERROR_SYSCALL", fromHostIP);
				ABORT_FINALIZE(RS_RET_NO_ERRCODE);
			} else {
				nsd_ossl_lastOpenSSLErrorMsg(pNsd, res, pNsd->pNetOssl->ssl, LOG_ERR,
					"osslHandshakeCheck Server", "SSL_accept");
				LogMsg(0, RS_RET_NO_ERRCODE, LOG_WARNING,
					"nsd_ossl:TLS session terminated with remote client '%s': "
					"Handshake failed with error code: %d", fromHostIP, resErr);
				ABORT_FINALIZE(RS_RET_NO_ERRCODE);
			}
		}
	} else {
		/* Handle Client SSL Object */
		if((res = SSL_do_handshake(pNsd->pNetOssl->ssl)) <= 0) {
			/* Obtain SSL Error code */
			nsd_ptcp.GetRemoteHName((nsd_t*)pNsd->pTcp, &fromHostIP);
			resErr = SSL_get_error(pNsd->pNetOssl->ssl, res);
			if(	resErr == SSL_ERROR_WANT_READ ||
				resErr == SSL_ERROR_WANT_WRITE) {
				pNsd->rtryCall = osslRtry_handshake;
				pNsd->rtryOsslErr = resErr; /* Store SSL ErrorCode into*/
				dbgprintf("osslHandshakeCheck: OpenSSL Client handshake does not complete "
					"immediately - setting to retry (this is OK and normal)\n");
				FINALIZE;
			} else if(resErr == SSL_ERROR_SYSCALL) {
				dbgprintf("osslHandshakeCheck: OpenSSL Client handshake failed with SSL_ERROR_SYSCALL "
					"- Aborting handshake.\n");
				nsd_ossl_lastOpenSSLErrorMsg(pNsd, res, pNsd->pNetOssl->ssl, LOG_WARNING,
					"osslHandshakeCheck Client", "SSL_do_handshake");
				ABORT_FINALIZE(RS_RET_NO_ERRCODE /*RS_RET_RETRY*/);
			} else {
				dbgprintf("osslHandshakeCheck: OpenSSL Client handshake failed with %d "
					"- Aborting handshake.\n", resErr);
				nsd_ossl_lastOpenSSLErrorMsg(pNsd, res, pNsd->pNetOssl->ssl, LOG_ERR,
					"osslHandshakeCheck Client", "SSL_do_handshake");
				LogMsg(0, RS_RET_NO_ERRCODE, LOG_WARNING,
					"nsd_ossl:TLS session terminated with remote syslog server '%s':"
					"Handshake failed with error code: %d", fromHostIP, resErr);
				ABORT_FINALIZE(RS_RET_NO_ERRCODE);
			}
		}
	}

	/* Do post handshake stuff */
	CHKiRet(osslPostHandshakeCheck(pNsd));

	/* Now check authorization */
	CHKiRet(osslChkPeerAuth(pNsd));
finalize_it:
	if (fromHostIP != NULL) {
		free(fromHostIP);
	}
	if(iRet == RS_RET_OK) {
		/* If no error occurred, set socket to SSL mode */
		pNsd->iMode = 1;
	}

	RETiRet;
}

/* accept an incoming connection request - here, we do the usual accept
 * handling. TLS specific handling is done thereafter (and if we run in TLS
 * mode at this time).
 * rgerhards, 2008-04-25
 */
static rsRetVal
AcceptConnReq(nsd_t *pNsd, nsd_t **ppNew)
{
	DEFiRet;
	nsd_ossl_t *pNew = NULL;
	nsd_ossl_t *pThis = (nsd_ossl_t*) pNsd;

	ISOBJ_TYPE_assert((pThis), nsd_ossl);
	CHKiRet(nsd_osslConstruct(&pNew));
	CHKiRet(nsd_ptcp.Destruct(&pNew->pTcp));
	dbgprintf("AcceptConnReq for [%p]: Accepting connection ... \n", (void *)pThis);
	CHKiRet(nsd_ptcp.AcceptConnReq(pThis->pTcp, &pNew->pTcp));

	if(pThis->iMode == 0) {
		/*we are in non-TLS mode, so we are done */
		DBGPRINTF("AcceptConnReq: NOT in TLS mode!\n");
		*ppNew = (nsd_t*) pNew;
		FINALIZE;
	}

	/* If we reach this point, we are in TLS mode */
	pNew->pNetOssl->authMode = pThis->pNetOssl->authMode;
	pNew->permitExpiredCerts = pThis->permitExpiredCerts;
	pNew->pNetOssl->pPermPeers = pThis->pNetOssl->pPermPeers;
	pNew->DrvrVerifyDepth = pThis->DrvrVerifyDepth;
	pNew->gnutlsPriorityString = pThis->gnutlsPriorityString;
	pNew->pNetOssl->ctx = pThis->pNetOssl->ctx;
	pNew->pNetOssl->ctx_is_copy = 1; // do not free on pNew Destruction
	CHKiRet(osslInitSession(pNew, osslServer));

	/* Store nsd_ossl_t* reference in SSL obj */
	SSL_set_ex_data(pNew->pNetOssl->ssl, 0, pThis->pTcp);
	SSL_set_ex_data(pNew->pNetOssl->ssl, 1, &pThis->permitExpiredCerts);

	/* We now do the handshake */
	CHKiRet(osslHandshakeCheck(pNew));

	*ppNew = (nsd_t*) pNew;
finalize_it:
	/* Accept appears to be done here */
	if(pNew != NULL) {
		DBGPRINTF("AcceptConnReq: END iRet = %d, pNew=[%p], pNsd->rtryCall=%d\n",
			iRet, pNew, pNew->rtryCall);
	}
	if(iRet != RS_RET_OK) {
		if(pNew != NULL) {
			nsd_osslDestruct(&pNew);
		}
	}
	RETiRet;
}


/* receive data from a tcp socket
 * The lenBuf parameter must contain the max buffer size on entry and contains
 * the number of octets read on exit. This function
 * never blocks, not even when called on a blocking socket. That is important
 * for client sockets, which are set to block during send, but should not
 * block when trying to read data. -- rgerhards, 2008-03-17
 * The function now follows the usual iRet calling sequence.
 * With GnuTLS, we may need to restart a recv() system call. If so, we need
 * to supply the SAME buffer on the retry. We can not assure this, as the
 * caller is free to call us with any buffer location (and in current
 * implementation, it is on the stack and extremely likely to change). To
 * work-around this problem, we allocate a buffer ourselfs and always receive
 * into that buffer. We pass data on to the caller only after we have received it.
 * To save some space, we allocate that internal buffer only when it is actually
 * needed, which means when we reach this function for the first time. To keep
 * the algorithm simple, we always supply data only from the internal buffer,
 * even if it is a single byte. As we have a stream, the caller must be prepared
 * to accept messages in any order, so we do not need to take care about this.
 * Please note that the logic also forces us to do some "faking" in select(), as
 * we must provide a fake "is ready for readign" status if we have data inside our
 * buffer. -- rgerhards, 2008-06-23
 */
static rsRetVal
Rcv(nsd_t *pNsd, uchar *pBuf, ssize_t *pLenBuf, int *const oserr)
{
	DEFiRet;
	ssize_t iBytesCopy; /* how many bytes are to be copied to the client buffer? */
	nsd_ossl_t *pThis = (nsd_ossl_t*) pNsd;
	ISOBJ_TYPE_assert(pThis, nsd_ossl);
	DBGPRINTF("Rcv for %p\n", pNsd);

	if(pThis->bAbortConn)
		ABORT_FINALIZE(RS_RET_CONNECTION_ABORTREQ);

	if(pThis->iMode == 0) {
		CHKiRet(nsd_ptcp.Rcv(pThis->pTcp, pBuf, pLenBuf, oserr));
		FINALIZE;
	}

	/* --- in TLS mode now --- */

	/* Buffer logic applies only if we are in TLS mode. Here we
	 * assume that we will switch from plain to TLS, but never back. This
	 * assumption may be unsafe, but it is the model for the time being and I
	 * do not see any valid reason why we should switch back to plain TCP after
	 * we were in TLS mode. However, in that case we may lose something that
	 * is already in the receive buffer ... risk accepted. -- rgerhards, 2008-06-23
	 */

	if(pThis->pszRcvBuf == NULL) {
		/* we have no buffer, so we need to malloc one */
		CHKmalloc(pThis->pszRcvBuf = malloc(NSD_OSSL_MAX_RCVBUF));
		pThis->lenRcvBuf = -1;
	}

	/* now check if we have something in our buffer. If so, we satisfy
	 * the request from buffer contents.
	 */
	if(pThis->lenRcvBuf == -1) { /* no data present, must read */
		CHKiRet(osslRecordRecv(pThis));
	}

	if(pThis->lenRcvBuf == 0) { /* EOS */
		*oserr = errno;
		ABORT_FINALIZE(RS_RET_CLOSED);
	}

	/* if we reach this point, data is present in the buffer and must be copied */
	iBytesCopy = pThis->lenRcvBuf - pThis->ptrRcvBuf;
	if(iBytesCopy > *pLenBuf) {
		iBytesCopy = *pLenBuf;
	} else {
		pThis->lenRcvBuf = -1; /* buffer will be emptied below */
	}

	memcpy(pBuf, pThis->pszRcvBuf + pThis->ptrRcvBuf, iBytesCopy);
	pThis->ptrRcvBuf += iBytesCopy;
	*pLenBuf = iBytesCopy;

finalize_it:
	if (iRet != RS_RET_OK) {
		if (iRet == RS_RET_CLOSED) {
			if (pThis->pNetOssl->ssl != NULL) {
				/* Set SSL Shutdown */
				SSL_shutdown(pThis->pNetOssl->ssl);
				dbgprintf("osslRcv SSL_shutdown done\n");
			}
		} else if (iRet != RS_RET_RETRY) {
			/* We need to free the receive buffer in error error case unless a retry is wanted. , if we
			 * allocated one. -- rgerhards, 2008-12-03 -- moved here by alorbach, 2015-12-01
			 */
			*pLenBuf = 0;
			free(pThis->pszRcvBuf);
			pThis->pszRcvBuf = NULL;
		} else {
			/* RS_RET_RETRY | Check for SSL Shutdown */
			if (SSL_get_shutdown(pThis->pNetOssl->ssl) == SSL_RECEIVED_SHUTDOWN) {
				dbgprintf("osslRcv received SSL_RECEIVED_SHUTDOWN!\n");
				iRet = RS_RET_CLOSED;

				/* Send Shutdown message back */
				SSL_shutdown(pThis->pNetOssl->ssl);
			}
		}
	}
	dbgprintf("osslRcv return. nsd %p, iRet %d, lenRcvBuf %d, ptrRcvBuf %d\n", pThis,
	iRet, pThis->lenRcvBuf, pThis->ptrRcvBuf);
	RETiRet;
}


/* send a buffer. On entry, pLenBuf contains the number of octets to
 * write. On exit, it contains the number of octets actually written.
 * If this number is lower than on entry, only a partial buffer has
 * been written.
 * rgerhards, 2008-03-19
 */
static rsRetVal
Send(nsd_t *pNsd, uchar *pBuf, ssize_t *pLenBuf)
{
	DEFiRet;
	int iSent;
	int err;
	nsd_ossl_t *pThis = (nsd_ossl_t*) pNsd;
	DBGPRINTF("Send for %p\n", pNsd);

	ISOBJ_TYPE_assert(pThis, nsd_ossl);

	if(pThis->bAbortConn)
		ABORT_FINALIZE(RS_RET_CONNECTION_ABORTREQ);

	if(pThis->iMode == 0) {
		CHKiRet(nsd_ptcp.Send(pThis->pTcp, pBuf, pLenBuf));
		FINALIZE;
	}

	while(1) {
		iSent = SSL_write(pThis->pNetOssl->ssl, pBuf, *pLenBuf);
		if(iSent > 0) {
			*pLenBuf = iSent;
			break;
		} else {
			err = SSL_get_error(pThis->pNetOssl->ssl, iSent);
			if(	err == SSL_ERROR_ZERO_RETURN ) {
				DBGPRINTF("Send: SSL_ERROR_ZERO_RETURN received, retry next time\n");
				ABORT_FINALIZE(RS_RET_RETRY);
			}
			else if(err == SSL_ERROR_SYSCALL) {
				/* Output error and abort */
				nsd_ossl_lastOpenSSLErrorMsg(pThis, iSent, pThis->pNetOssl->ssl, LOG_INFO,
					"Send", "SSL_write");
				iRet = RS_RET_NO_ERRCODE;
				/* Check for underlaying socket errors **/
				if (	errno == ECONNRESET) {
					dbgprintf("Send: SSL_ERROR_SYSCALL Connection was reset by remote\n");
					/* Connection was dropped from remote site */
					iRet = RS_RET_CLOSED;
				} else {
					DBGPRINTF("Send: SSL_ERROR_SYSCALL Errno %d\n", errno);
				}
				ABORT_FINALIZE(iRet);
			}
			else if(err != SSL_ERROR_WANT_READ &&
				err != SSL_ERROR_WANT_WRITE) {
				/* Output error and abort */
				nsd_ossl_lastOpenSSLErrorMsg(pThis, iSent, pThis->pNetOssl->ssl, LOG_ERR,
					"Send", "SSL_write");
				ABORT_FINALIZE(RS_RET_NO_ERRCODE);
			} else {
				/* Check for SSL Shutdown */
				if (SSL_get_shutdown(pThis->pNetOssl->ssl) == SSL_RECEIVED_SHUTDOWN) {
					dbgprintf("osslRcv received SSL_RECEIVED_SHUTDOWN!\n");
					ABORT_FINALIZE(RS_RET_CLOSED);
				}
			}
		}
	}
finalize_it:
	RETiRet;
}


/* Enable KEEPALIVE handling on the socket.
 * rgerhards, 2009-06-02
 */
static rsRetVal
EnableKeepAlive(nsd_t *pNsd)
{
	nsd_ossl_t *pThis = (nsd_ossl_t*) pNsd;
	ISOBJ_TYPE_assert(pThis, nsd_ossl);
	return nsd_ptcp.EnableKeepAlive(pThis->pTcp);
}


/* open a connection to a remote host (server). With OpenSSL, we always
 * open a plain tcp socket and then, if in TLS mode, do a handshake on it.
 */
static rsRetVal
Connect(nsd_t *pNsd, int family, uchar *port, uchar *host, char *device)
{
	DEFiRet;
	DBGPRINTF("openssl: entering Connect family=%d, device=%s\n", family, device);
	nsd_ossl_t* pThis = (nsd_ossl_t*) pNsd;

	ISOBJ_TYPE_assert(pThis, nsd_ossl);
	assert(port != NULL);
	assert(host != NULL);

	/* Create main CTX Object. Use SSLv23_method for < Openssl 1.1.0 and TLS_method for all newer versions! */
#if OPENSSL_VERSION_NUMBER < 0x10100000L
	CHKiRet(net_ossl.osslCtxInit(pThis->pNetOssl, SSLv23_method()));
#else
	CHKiRet(net_ossl.osslCtxInit(pThis->pNetOssl, TLS_method()));
#endif
	// Apply PriorityString after Ctx Creation
	applyGnutlsPriorityString(pThis);

	// Perform TCP Connect
	CHKiRet(nsd_ptcp.Connect(pThis->pTcp, family, port, host, device));

	if(pThis->iMode == 0) {
		/*we are in non-TLS mode, so we are done */
		DBGPRINTF("Connect: NOT in TLS mode!\n");
		FINALIZE;
	}

	LogMsg(0, RS_RET_NO_ERRCODE, LOG_INFO, "nsd_ossl: "
		"TLS Connection initiated with remote syslog server.");
	/*if we reach this point we are in tls mode */
	DBGPRINTF("Connect: TLS Mode\n");

	/* Do SSL Session init */
	CHKiRet(osslInitSession(pThis, osslClient));

	/* Store nsd_ossl_t* reference in SSL obj */
	SSL_set_ex_data(pThis->pNetOssl->ssl, 0, pThis->pTcp);
	SSL_set_ex_data(pThis->pNetOssl->ssl, 1, &pThis->permitExpiredCerts);

	/* We now do the handshake */
	iRet = osslHandshakeCheck(pThis);
finalize_it:
	/* Connect appears to be done here */
	dbgprintf("Connect: END iRet = %d, pThis=[%p], pNsd->rtryCall=%d\n",
		iRet, pThis, pThis->rtryCall);
	if(iRet != RS_RET_OK) {
		if(pThis->bHaveSess) {
			pThis->bHaveSess = 0;
			SSL_free(pThis->pNetOssl->ssl);
			pThis->pNetOssl->ssl = NULL;
		}
	}
	RETiRet;
}

static rsRetVal
SetGnutlsPriorityString(nsd_t *const pNsd, uchar *const gnutlsPriorityString)
{
	DEFiRet;
	nsd_ossl_t* pThis = (nsd_ossl_t*) pNsd;
	ISOBJ_TYPE_assert(pThis, nsd_ossl);

#if OPENSSL_VERSION_NUMBER >= 0x10002000L && !defined(LIBRESSL_VERSION_NUMBER)
	sbool ApplySettings = 0;
	if (	(gnutlsPriorityString != NULL && pThis->gnutlsPriorityString == NULL) ||
		(gnutlsPriorityString != NULL &&
		strcmp( (const char*)pThis->gnutlsPriorityString, (const char*)gnutlsPriorityString) != 0)
		) {
		ApplySettings = 1;
	}

	pThis->gnutlsPriorityString = gnutlsPriorityString;
	dbgprintf("gnutlsPriorityString: set to '%s' Apply %s\n",
		(gnutlsPriorityString != NULL ? (char*)gnutlsPriorityString : "NULL"),
		(ApplySettings == 1? "TRUE" : "FALSE"));
	if (ApplySettings == 1) {
		/* Apply Settings if necessary */
		applyGnutlsPriorityString(pThis);
	}

#else
	LogError(0, RS_RET_SYS_ERR, "Warning: TLS library does not support SSL_CONF_cmd API"
		"(maybe it is too old?). Cannot use gnutlsPriorityString ('%s'). For more see: "
		"https://www.rsyslog.com/doc/master/configuration/modules/imtcp.html#gnutlsprioritystring",
		gnutlsPriorityString);
#endif
	RETiRet;
}


static rsRetVal
applyGnutlsPriorityString(nsd_ossl_t *const pThis)
{
	DEFiRet;
	ISOBJ_TYPE_assert(pThis, nsd_ossl);

#if OPENSSL_VERSION_NUMBER >= 0x10002000L && !defined(LIBRESSL_VERSION_NUMBER)
	/* Note: we disable unkonwn functions. The corresponding error message is
	 * generated during SetGntuTLSPriorityString().
	 */
	if(pThis->gnutlsPriorityString == NULL || pThis->pNetOssl->ctx == NULL) {
		FINALIZE;
	} else {
		CHKiRet(net_ossl_apply_tlscgfcmd(pThis->pNetOssl, pThis->gnutlsPriorityString));
	}
#endif

finalize_it:
	RETiRet;
}

/* Set the driver cert extended key usage check setting, for now it is empty wrapper.
 * TODO: implement openSSL version
 * jvymazal, 2019-08-16
 */
static rsRetVal
SetCheckExtendedKeyUsage(nsd_t __attribute__((unused)) *pNsd, int ChkExtendedKeyUsage)
{
	DEFiRet;
	if(ChkExtendedKeyUsage != 0) {
		LogError(0, RS_RET_VALUE_NOT_SUPPORTED, "error: driver ChkExtendedKeyUsage %d "
				"not supported by ossl netstream driver", ChkExtendedKeyUsage);
		ABORT_FINALIZE(RS_RET_VALUE_NOT_SUPPORTED);
	}
finalize_it:
	RETiRet;
}

/* Set the driver name checking strictness, for now it is empty wrapper.
 * TODO: implement openSSL version
 * jvymazal, 2019-08-16
 */
static rsRetVal
SetPrioritizeSAN(nsd_t __attribute__((unused)) *pNsd, int prioritizeSan)
{
	DEFiRet;
	if(prioritizeSan != 0) {
		LogError(0, RS_RET_VALUE_NOT_SUPPORTED, "error: driver prioritizeSan %d "
				"not supported by ossl netstream driver", prioritizeSan);
		ABORT_FINALIZE(RS_RET_VALUE_NOT_SUPPORTED);
	}
finalize_it:
	RETiRet;
}

/* Set the driver tls  verifyDepth
 * alorbach, 2019-12-20
 */
static rsRetVal
SetTlsVerifyDepth(nsd_t *pNsd, int verifyDepth)
{
	DEFiRet;
	nsd_ossl_t *pThis = (nsd_ossl_t*) pNsd;

	ISOBJ_TYPE_assert((pThis), nsd_ossl);
	if (verifyDepth == 0) {
		FINALIZE;
	}
	assert(verifyDepth >= 2);
	pThis->DrvrVerifyDepth = verifyDepth;

finalize_it:
	RETiRet;
}


static rsRetVal
SetTlsCAFile(nsd_t *pNsd, const uchar *const caFile)
{
	DEFiRet;
	nsd_ossl_t *const pThis = (nsd_ossl_t*) pNsd;

	ISOBJ_TYPE_assert((pThis), nsd_ossl);
	if(caFile == NULL) {
		pThis->pNetOssl->pszCAFile = NULL;
	} else {
		CHKmalloc(pThis->pNetOssl->pszCAFile = (const uchar*) strdup((const char*) caFile));
	}

finalize_it:
	RETiRet;
}

static rsRetVal
SetTlsCRLFile(nsd_t *pNsd, const uchar *const crlFile)
{
	DEFiRet;
	nsd_ossl_t *const pThis = (nsd_ossl_t*) pNsd;

	ISOBJ_TYPE_assert((pThis), nsd_ossl);
	if(crlFile == NULL) {
		pThis->pNetOssl->pszCRLFile = NULL;
	} else {
		CHKmalloc(pThis->pNetOssl->pszCRLFile = (const uchar*) strdup((const char*) crlFile));
	}

finalize_it:
	RETiRet;
}


static rsRetVal
SetTlsKeyFile(nsd_t *pNsd, const uchar *const pszFile)
{
	DEFiRet;
	nsd_ossl_t *const pThis = (nsd_ossl_t*) pNsd;

	ISOBJ_TYPE_assert((pThis), nsd_ossl);
	if(pszFile == NULL) {
		pThis->pNetOssl->pszKeyFile = NULL;
	} else {
		CHKmalloc(pThis->pNetOssl->pszKeyFile = (const uchar*) strdup((const char*) pszFile));
	}

finalize_it:
	RETiRet;
}

static rsRetVal
SetTlsCertFile(nsd_t *pNsd, const uchar *const pszFile)
{
	DEFiRet;
	nsd_ossl_t *const pThis = (nsd_ossl_t*) pNsd;

	ISOBJ_TYPE_assert((pThis), nsd_ossl);
	if(pszFile == NULL) {
		pThis->pNetOssl->pszCertFile = NULL;
	} else {
		CHKmalloc(pThis->pNetOssl->pszCertFile = (const uchar*) strdup((const char*) pszFile));
	}

finalize_it:
	RETiRet;
}


/* queryInterface function */
BEGINobjQueryInterface(nsd_ossl)
CODESTARTobjQueryInterface(nsd_ossl)
	if(pIf->ifVersion != nsdCURR_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 = (rsRetVal(*)(nsd_t**)) nsd_osslConstruct;
	pIf->Destruct = (rsRetVal(*)(nsd_t**)) nsd_osslDestruct;
	pIf->Abort = Abort;
	pIf->LstnInit = LstnInit;
	pIf->AcceptConnReq = AcceptConnReq;
	pIf->Rcv = Rcv;
	pIf->Send = Send;
	pIf->Connect = Connect;
	pIf->SetSock = SetSock;
	pIf->SetMode = SetMode;
	pIf->SetAuthMode = SetAuthMode;
	pIf->SetPermitExpiredCerts = SetPermitExpiredCerts;
	pIf->SetPermPeers =SetPermPeers;
	pIf->CheckConnection = CheckConnection;
	pIf->GetRemoteHName = GetRemoteHName;
	pIf->GetRemoteIP = GetRemoteIP;
	pIf->GetRemAddr = GetRemAddr;
	pIf->EnableKeepAlive = EnableKeepAlive;
	pIf->SetKeepAliveIntvl = SetKeepAliveIntvl;
	pIf->SetKeepAliveProbes = SetKeepAliveProbes;
	pIf->SetKeepAliveTime = SetKeepAliveTime;
	pIf->SetGnutlsPriorityString = SetGnutlsPriorityString; /* we don't NEED this interface! */
	pIf->SetCheckExtendedKeyUsage = SetCheckExtendedKeyUsage; /* we don't NEED this interface! */
	pIf->SetPrioritizeSAN = SetPrioritizeSAN; /* we don't NEED this interface! */
	pIf->SetTlsVerifyDepth = SetTlsVerifyDepth;
	pIf->SetTlsCAFile = SetTlsCAFile;
	pIf->SetTlsCRLFile = SetTlsCRLFile;
	pIf->SetTlsKeyFile = SetTlsKeyFile;
	pIf->SetTlsCertFile = SetTlsCertFile;

finalize_it:
ENDobjQueryInterface(nsd_ossl)


/* exit our class
 */
BEGINObjClassExit(nsd_ossl, OBJ_IS_LOADABLE_MODULE) /* CHANGE class also in END MACRO! */
CODESTARTObjClassExit(nsd_ossl)
	/* release objects we no longer need */
	objRelease(net_ossl, CORE_COMPONENT);
	objRelease(nsd_ptcp, LM_NSD_PTCP_FILENAME);
	objRelease(net, LM_NET_FILENAME);
	objRelease(glbl, CORE_COMPONENT);
	objRelease(datetime, CORE_COMPONENT);
ENDObjClassExit(nsd_ossl)


/* Initialize the nsd_ossl class. Must be called as the very first method
 * before anything else is called inside this class.
 */
BEGINObjClassInit(nsd_ossl, 1, OBJ_IS_LOADABLE_MODULE) /* class, version */
	/* request objects we use */
	CHKiRet(objUse(datetime, CORE_COMPONENT));
	CHKiRet(objUse(glbl, CORE_COMPONENT));
	CHKiRet(objUse(net, LM_NET_FILENAME));
	CHKiRet(objUse(nsd_ptcp, LM_NSD_PTCP_FILENAME));
	CHKiRet(objUse(net_ossl, CORE_COMPONENT));
ENDObjClassInit(nsd_ossl)


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


BEGINmodExit
CODESTARTmodExit
	nsdsel_osslClassExit();
	nsd_osslClassExit();
	net_osslClassExit();
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(net_osslClassInit(pModInfo)); /* must be done after tcps_sess, as we use it */
	CHKiRet(nsd_osslClassInit(pModInfo)); /* must be done after tcps_sess, as we use it */
	CHKiRet(nsdsel_osslClassInit(pModInfo)); /* must be done after tcps_sess, as we use it */
ENDmodInit