toxcore/toxav/rtp.h

/*
 * Copyright © 2016-2017 The TokTok team.
 * Copyright © 2013-2015 Tox project.
 *
 * This file is part of Tox, the free peer to peer instant messenger.
 *
 * Tox 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.
 *
 * Tox 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 Tox.  If not, see <http://www.gnu.org/licenses/>.
 */
#ifndef RTP_H
#define RTP_H

#include "bwcontroller.h"

#include "../toxcore/Messenger.h"
#include "../toxcore/logger.h"

#include <stdbool.h>

/**
 * Payload type identifier. Also used as rtp callback prefix.
 */
enum {
    rtp_TypeAudio = 192,
    rtp_TypeVideo = 193,
};

/**
 * A bit mask (up to 64 bits) specifying features of the current frame affecting
 * the behaviour of the decoder.
 */
enum RTPFlags {
    /**
     * Support frames larger than 64KiB. The full 32 bit length and offset are
     * set in \ref RTPHeader::data_length_full and \ref RTPHeader::offset_full.
     */
    RTP_LARGE_FRAME = 1 << 0,
    /**
     * Whether the packet is part of a key frame.
     */
    RTP_KEY_FRAME = 1 << 1,
};

struct RTPHeader {
    /* Standard RTP header */
#ifndef WORDS_BIGENDIAN
    uint16_t cc: 4; /* Contributing sources count */
    uint16_t xe: 1; /* Extra header */
    uint16_t pe: 1; /* Padding */
    uint16_t protocol_version: 2; /* Version has only 2 bits! */

    uint16_t pt: 7; /* Payload type */
    uint16_t ma: 1; /* Marker */
#else
    uint16_t protocol_version: 2; /* Version has only 2 bits! */
    uint16_t pe: 1; /* Padding */
    uint16_t xe: 1; /* Extra header */
    uint16_t cc: 4; /* Contributing sources count */

    uint16_t ma: 1; /* Marker */
    uint16_t pt: 7; /* Payload type */
#endif

    uint16_t sequnum;
    uint32_t timestamp;
    uint32_t ssrc;

    /* Non-standard Tox-specific fields */

    /**
     * Bit mask of \ref RTPFlags setting features of the current frame.
     */
    uint64_t flags;

    /**
     * The full 32 bit data offset of the current data chunk. The \ref
     * offset_lower data member contains the lower 16 bits of this value. For
     * frames smaller than 64KiB, \ref offset_full and \ref offset_lower are
     * equal.
     */
    uint32_t offset_full;
    /**
     * The full 32 bit payload length without header and packet id.
     */
    uint32_t data_length_full;
    /**
     * Only the receiver uses this field (why do we have this?).
     */
    uint32_t received_length_full;

    /**
     * Unused fields. If you want to add more information to this header, remove
     * one csrc and add the appropriate number of fields in its place.
     */
    uint32_t csrc[11];

    /**
     * Data offset of the current part (lower bits).
     */
    uint16_t offset_lower;
    /**
     * Total message length (lower bits).
     */
    uint16_t data_length_lower;
} __attribute__((packed));

/* Check alignment */
typedef char __fail_if_misaligned_1 [ sizeof(struct RTPHeader) == 80 ? 1 : -1 ];

struct RTPMessage {
    uint16_t len;

    struct RTPHeader header;
    uint8_t data[];
} __attribute__((packed));

/* Check alignment */
typedef char __fail_if_misaligned_2 [ sizeof(struct RTPMessage) == 82 ? 1 : -1 ];

/**
 * RTP control session.
 */
typedef struct {
    uint8_t  payload_type;
    uint16_t sequnum;      /* Sending sequence number */
    uint16_t rsequnum;     /* Receiving sequence number */
    uint32_t rtimestamp;
    uint32_t ssrc;

    struct RTPMessage *mp; /* Expected parted message */

    Messenger *m;
    uint32_t friend_number;

    BWController *bwc;
    void *cs;
    int (*mcb)(void *, struct RTPMessage *msg);
} RTPSession;


RTPSession *rtp_new(int payload_type, Messenger *m, uint32_t friendnumber,
                    BWController *bwc, void *cs,
                    int (*mcb)(void *, struct RTPMessage *));
void rtp_kill(RTPSession *session);
int rtp_allow_receiving(RTPSession *session);
int rtp_stop_receiving(RTPSession *session);
int rtp_send_data(RTPSession *session, const uint8_t *data, uint16_t length, Logger *log);

#endif /* RTP_H */