/*
 * Copyright (c) 2010-2022 Belledonne Communications SARL.
 *
 * This file is part of mediastreamer2
 * (see https://gitlab.linphone.org/BC/public/mediastreamer2).
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * This program 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 Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 */

#ifndef ms_dtls_srtp_h
#define ms_dtls_srtp_h

#include "mediastreamer2/mscommon.h"
#include <ortp/rtpsession.h>

#ifdef __cplusplus
extern "C" {
#endif

/* defined in mediastream.h */
struct _MSMediaStreamSessions;

typedef enum _MSDtlsError {
	MS_DTLS_ERROR_NONE,
	MS_DTLS_ERROR_CERT_VERIFY_FAIL,
	MS_DTLS_ERROR_CERT_SUBJECT_UNMATCHING,
	MS_DTLS_ERROR_HANDSHAKE_FAIL_TO_GENERATE_SRTP_KEYS,
	MS_DTLS_ERROR_HANDSHAKE_FAIL_FATAL_ALERT,
} MSDtlsError;

typedef enum {
	MSDtlsSrtpRoleInvalid,
	MSDtlsSrtpRoleIsServer,
	MSDtlsSrtpRoleIsClient,
	MSDtlsSrtpRoleUnset
} MSDtlsSrtpRole;

typedef struct MSDtlsSrtpParams {
	const char *pem_certificate; /**< Self certificate in pem format */
	const char *pem_pkey;        /**< Private key associated to self certificate */
	const char *root_ca;         /**< Path to root certicates authority */
	MSDtlsSrtpRole role; /**< Unset(at caller init, role is then choosen by responder but we must still be able to
	                    receive packets) */
	int mtu;
	bool_t verify_certificate; /**< when set, accept only valid certificates */
	const char *peer_uri;      /**< peer's uri retrieved from the SDP */
} MSDtlsSrtpParams;

/* an opaque structure containing all context data needed by DTLS-SRTP */
typedef struct _MSDtlsSrtpContext MSDtlsSrtpContext;

/**
 * check if DTLS-SRTP is available
 * @return TRUE if it is available, FALSE if not
 */
MS2_PUBLIC bool_t ms_dtls_srtp_available(void);

/**
 * Create an initialise a DTLS-SRTP context
 * @param[in]	sessions	A link to the stream sessions structures, used to get rtp session to add transport modifier
 * and needed to set SRTP sessions when keys are ready
 * @param[in]	params		Self certificate and private key to be used for this session. Role (client/server) may be
 * given but can be set later
 * @return	a pointer to the opaque context structure needed by DTLS-SRTP
 */
MS2_PUBLIC MSDtlsSrtpContext *ms_dtls_srtp_context_new(struct _MSMediaStreamSessions *sessions,
                                                       MSDtlsSrtpParams *params);

/**
 * Start the DTLS-SRTP channel: send DTLS ClientHello if we are client
 * @param[in/out]	context		the DTLS-SRTP context
 */
MS2_PUBLIC void ms_dtls_srtp_start(MSDtlsSrtpContext *context);

/**
 * Free ressources used by DTLS-SRTP context
 * @param[in/out]	context		the DTLS-SRTP context
 */
MS2_PUBLIC void ms_dtls_srtp_context_destroy(MSDtlsSrtpContext *ctx);

/**
 * Reset DTLS context to renegotiate keys and carry out once again SSL handshake next time DTLS starts
 * @param[in/out]	context		the DTLS-SRTP context
 */
MS2_PUBLIC void ms_dtls_srtp_reset_context(MSDtlsSrtpContext *context);

/**
 * Set DTLS role: server or client, called when SDP exchange reach the point where we can determine self role
 * @param[in/out]	context		the DTLS-SRTP context
 * @param[in]		role		Client/Server/Invalid/Unset according to SDP INVITE processing
 */
MS2_PUBLIC void ms_dtls_srtp_set_role(MSDtlsSrtpContext *context, MSDtlsSrtpRole role);

/**
 * Get DTLS role: server or client, called when SDP exchange reach the point where we can determine self role
 * @param[in/out]	context		the DTLS-SRTP context
 * @return		role		Client/Server/Invalid/Unset according to SDP INVITE processing
 */
MS2_PUBLIC MSDtlsSrtpRole ms_dtls_srtp_get_role(const MSDtlsSrtpContext *context);

/**
 * Give to the DTLS-SRTP context the peer certificate fingerprint extracted from trusted SDP INVITE,
 * it will be compared(case insensitive) with locally computed one after DTLS handshake is completed successfully and
 * peer certicate retrieved
 * @param[in/out]	context			the DTLS-SRTP context
 * @param[in]		peer_fingerprint	a null terminated string containing the peer certificate as found in the SDP
 * INVITE(including the heading hash algorithm name)
 */
MS2_PUBLIC void ms_dtls_srtp_set_peer_fingerprint(MSDtlsSrtpContext *context, const char *peer_fingerprint);

#ifdef __cplusplus
}
#endif

#endif /* ms_dtls_srtp_h */
