rtp.h

/*
 * (c) 1998-2018 by Columbia University; all rights reserved
 *
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/*
 * rtp.h  --  RTP header file (RFC 1890)
 */
#include <stdint.h>
#include "sysdep.h"

/*
 * Current protocol version.
 */
#define RTP_VERSION    2

typedef enum {
    RTCP_SR   = 200,
    RTCP_RR   = 201,
    RTCP_SDES = 202,
    RTCP_BYE  = 203,
    RTCP_APP  = 204
} rtcp_type_t;

typedef enum {
    RTCP_SDES_END   = 0,
    RTCP_SDES_CNAME = 1,
    RTCP_SDES_NAME  = 2,
    RTCP_SDES_EMAIL = 3,
    RTCP_SDES_PHONE = 4,
    RTCP_SDES_LOC   = 5,
    RTCP_SDES_TOOL  = 6,
    RTCP_SDES_NOTE  = 7,
    RTCP_SDES_PRIV  = 8
} rtcp_sdes_type_t;

/*
 * RTP data header
 */
typedef struct {
#if RTP_BIG_ENDIAN
    unsigned int version:2;   /* protocol version */
    unsigned int p:1;         /* padding flag */
    unsigned int x:1;         /* header extension flag */
    unsigned int cc:4;        /* CSRC count */
    unsigned int m:1;         /* marker bit */
    unsigned int pt:7;        /* payload type */
#else
    unsigned int cc:4;        /* CSRC count */
    unsigned int x:1;         /* header extension flag */
    unsigned int p:1;         /* padding flag */
    unsigned int version:2;   /* protocol version */
    unsigned int pt:7;        /* payload type */
    unsigned int m:1;         /* marker bit */
#endif
    unsigned int seq:16;      /* sequence number */
    uint32_t ts;               /* timestamp */
    uint32_t ssrc;             /* synchronization source */
    uint32_t csrc[1];          /* optional CSRC list */
} rtp_hdr_t;

/* RTP Header Extension
 */
typedef struct {
    uint16_t ext_type;         /* defined by profile */
    uint16_t len;              /* extension length in 32-bit word */
} rtp_hdr_ext_t;

/*
 * RTCP common header word
 */
typedef struct {
#if RTP_BIG_ENDIAN
    unsigned int version:2;   /* protocol version */
    unsigned int p:1;         /* padding flag */
    unsigned int count:5;     /* varies by packet type */
#else
    unsigned int count:5;     /* varies by packet type */
    unsigned int p:1;         /* padding flag */
    unsigned int version:2;   /* protocol version */
#endif
    unsigned int pt:8;        /* RTCP packet type */
    unsigned int length:16;   /* pkt len in words, w/o this word */
} rtcp_common_t;

/*
 * Reception report block
 */
typedef struct {
    uint32_t ssrc;             /* data source being reported */
    unsigned int fraction:8;  /* fraction lost since last SR/RR */
    unsigned int lost_sb:1;    /* cumul. no. pkts lost: sign */
    unsigned int lost_b2:7;    /* cumul. no. pkts lost: MSB */
    unsigned int lost_b1:8;    /* cumul. no. pkts lost: byte 1 */
    unsigned int lost_b0:8;    /* cumul. no. pkts lost: LSB */
    uint32_t last_seq;         /* extended last seq. no. received */
    uint32_t jitter;           /* interarrival jitter */
    uint32_t lsr;              /* last SR packet from this source */
    uint32_t dlsr;             /* delay since last SR packet */
} rtcp_rr_t;

#define _BYTE(v) ((v) & 0xff)
#define RTCP_GET_LOST(rp) ((rp)->lost_sb ? (-1) : (1) * (((rp)->lost_b2 << 16) | ((rp)->lost_b1 << 8) | (rp)->lost_b0))
#define RTCP_SET_LOST(rp, v) do { \
    (rp)->lost_sb = (v) < 0 ? (1) : (0); \
    (rp)->lost_b2 = _BYTE((v) >> 16); \
    (rp)->lost_b1 = _BYTE((v) >> 8); \
    (rp)->lost_b0 = _BYTE((v)); \
  } while (0)

/*
 * SDES item
 */
typedef struct {
    uint8_t type;             /* type of item (rtcp_sdes_type_t) */
    uint8_t length;           /* length of item (in octets) */
    char data[1];             /* text, not null-terminated */
} rtcp_sdes_item_t;

/*
 * One RTCP packet
 */
typedef struct {
    rtcp_common_t common;     /* common header */
    union {
        /* sender report (SR) */
        struct {
            uint32_t ssrc;     /* sender generating this report */
            uint32_t ntp_sec;  /* NTP timestamp */
            uint32_t ntp_frac;
            uint32_t rtp_ts;   /* RTP timestamp */
            uint32_t psent;    /* packets sent */
            uint32_t osent;    /* octets sent */
            rtcp_rr_t rr[1];  /* variable-length list */
        } sr;

        /* reception report (RR) */
        struct {
            uint32_t ssrc;     /* receiver generating this report */
            rtcp_rr_t rr[1];  /* variable-length list */
        } rr;

        /* source description (SDES) */
        struct rtcp_sdes {
            uint32_t src;      /* first SSRC/CSRC */
            rtcp_sdes_item_t item[1]; /* list of SDES items */
        } sdes;

        /* BYE */
        struct {
            uint32_t src[1];   /* list of sources */
            /* can't express trailing text for reason */
        } bye;
    } r;
} rtcp_t;

typedef struct rtcp_sdes rtcp_sdes_t;