/* An implementation of the nsd interface for GnuTLS.
 *
 * Copyright 2008-2021 Adiscon GmbH.
 *
 * This file is part of the rsyslog runtime library.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *       http://www.apache.org/licenses/LICENSE-2.0
 *       -or-
 *       see COPYING.ASL20 in the source distribution
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#ifndef INCLUDED_NSD_GTLS_H
#define INCLUDED_NSD_GTLS_H

#include "nsd.h"

#define NSD_GTLS_MAX_RCVBUF 16 * 1024 + 1/* TLS RFC 8449: max size of buffer for message reception */
#define NSD_GTLS_MAX_CERT 10 /* max number of certs in our chain */

typedef enum {
	gtlsRtry_None = 0,	/**< no call needs to be retried */
	gtlsRtry_handshake = 1,
	gtlsRtry_recv = 2
} gtlsRtryCall_t;		/**< IDs of calls that needs to be retried */

typedef enum {
	gtlsDir_READ = 0,	/**< GNUTLS wants READ */
	gtlsDir_WRITE = 1	/**< GNUTLS wants WRITE */
} gtlsDirection_t;

typedef nsd_if_t nsd_gtls_if_t; /* we just *implement* this interface */

/* the nsd_gtls object */
struct nsd_gtls_s {
	BEGINobjInstance;	/* Data to implement generic object - MUST be the first data element! */
	nsd_t *pTcp;		/**< our aggregated nsd_ptcp data */
	uchar *pszConnectHost;	/**< hostname used for connect - may be used to
					authenticate peer if no other name given */
	const uchar *pszCAFile;
	const uchar *pszCRLFile;
	const uchar *pszKeyFile;
	const uchar *pszCertFile;
	gnutls_certificate_credentials_t xcred;
	int xcred_is_copy;
	int iMode;		/* 0 - plain tcp, 1 - TLS */
	int bAbortConn;		/* if set, abort conncection (fatal error had happened) */
	enum {
		GTLS_AUTH_CERTNAME = 0,
		GTLS_AUTH_CERTFINGERPRINT = 1,
		GTLS_AUTH_CERTVALID = 2,
		GTLS_AUTH_CERTANON = 3
	} authMode;
	enum {
		GTLS_EXPIRED_PERMIT = 0,
		GTLS_EXPIRED_DENY = 1,
		GTLS_EXPIRED_WARN = 2
	} permitExpiredCerts;
	enum {
		GTLS_NONE = 0,
		GTLS_PURPOSE = 1
	} dataTypeCheck;
	int bSANpriority; /* if true, we do stricter checking (if any SAN present we do not cehck CN) */
	gtlsRtryCall_t rtryCall;/**< what must we retry? */
	int bIsInitiator;	/**< 0 if socket is the server end (listener), 1 if it is the initiator */
	gnutls_session_t sess;
	int bHaveSess;		/* as we don't know exactly which gnutls_session values
					are invalid, we use this one to flag whether or
					not we are in a session (same as -1 for a socket
					meaning no sess) */
	int bReportAuthErr;	/* only the first auth error is to be reported, this var triggers it. Initially, it is
				 * set to 1 and changed to 0 after the first report. It is changed back to 1 after
				 * one successful authentication. */
	permittedPeers_t *pPermPeers; /* permitted peers */
	uchar *gnutlsPriorityString;	/* gnutls priority string */
	int DrvrVerifyDepth;		/* Verify Depth for certificate chains */
	gnutls_x509_crt_t pOurCerts[NSD_GTLS_MAX_CERT];	/**< our certificate, if in client mode
							(unused in server mode) */
	unsigned int nOurCerts;  /* number of certificates in our chain */
	gnutls_x509_privkey_t ourKey;	/**< our private key, if in client mode (unused in server mode) */
	short	bOurCertIsInit;	/**< 1 if our certificate is initialized and must be deinit on destruction */
	short	bOurKeyIsInit;	/**< 1 if our private key is initialized and must be deinit on destruction */
	char *pszRcvBuf;
	int lenRcvBuf;
	/**< -1: empty, 0: connection closed, 1..NSD_GTLS_MAX_RCVBUF-1: data of that size present */
	int ptrRcvBuf;		/**< offset for next recv operation if 0 < lenRcvBuf < NSD_GTLS_MAX_RCVBUF */
};

/* interface is defined in nsd.h, we just implement it! */
#define nsd_gtlsCURR_IF_VERSION nsdCURR_IF_VERSION

/* prototypes */
PROTOTYPEObj(nsd_gtls);
/* some prototypes for things used by our nsdsel_gtls helper class */
uchar *gtlsStrerror(int error);
rsRetVal gtlsChkPeerAuth(nsd_gtls_t *pThis);
rsRetVal gtlsRecordRecv(nsd_gtls_t *pThis);

/* the name of our library binary */
#define LM_NSD_GTLS_FILENAME "lmnsd_gtls"

#if GNUTLS_VERSION_NUMBER <= 0x00030000
#define GTLS_ANON_PRIO_NOTLSV13 "NORMAL:-VERS-TLS1.3:+ANON-DH:+COMP-ALL"
#define GTLS_ANON_PRIO "NORMAL:+ANON-DH:+COMP-ALL"
#else
#define GTLS_ANON_PRIO_NOTLSV13 "NORMAL:-VERS-TLS1.3:+ANON-DH:+ANON-ECDH:+COMP-ALL"
#define GTLS_ANON_PRIO "NORMAL:+ANON-DH:+ANON-ECDH:+COMP-ALL"
#endif

#if GNUTLS_VERSION_MAJOR > 3 || (GNUTLS_VERSION_MAJOR == 3 && GNUTLS_VERSION_MINOR >=4)
#define EXTENDED_CERT_CHECK_AVAILABLE
#endif

#endif /* #ifndef INCLUDED_NSD_GTLS_H */