root/modules/demux/rtp.c

/**
 * @file rtp.c
 * @brief Real-Time Protocol (RTP) demux module for VLC media player
 */
/*****************************************************************************
 * Copyright (C) 2001-2005 the VideoLAN team
 * Copyright © 2007-2008 Rémi Denis-Courmont
 *
 * This library 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 2.0
 * of the License, or (at your option) any later version.
 *
 * This 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 General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 ****************************************************************************/

#ifdef HAVE_CONFIG_H
# include <config.h>
#endif
#include <stdarg.h>
#include <assert.h>

#include <vlc_common.h>
#include <vlc_demux.h>
#include <vlc_aout.h>
#include <vlc_network.h>
#ifdef HAVE_POLL
# include <poll.h>
#endif
#include <vlc_plugin.h>

#include <vlc_codecs.h>

#include "rtp.h"
#include <srtp.h>

#define RTP_CACHING_TEXT N_("RTP de-jitter buffer length (msec)")
#define RTP_CACHING_LONGTEXT N_( \
    "How long to wait for late RTP packets (and delay the performance)." )

#define SRTP_KEY_TEXT N_("SRTP key (hexadecimal)")
#define SRTP_KEY_LONGTEXT N_( \
    "RTP packets will be authenticated and deciphered "\
    "with this Secure RTP master shared secret key.")

#define SRTP_SALT_TEXT N_("SRTP salt (hexadecimal)")
#define SRTP_SALT_LONGTEXT N_( \
    "Secure RTP requires a (non-secret) master salt value.")

#define RTP_MAX_SRC_TEXT N_("Maximum RTP sources")
#define RTP_MAX_SRC_LONGTEXT N_( \
    "How many distinct active RTP sources are allowed at a time." )

#define RTP_TIMEOUT_TEXT N_("RTP source timeout (sec)")
#define RTP_TIMEOUT_LONGTEXT N_( \
    "How long to wait for any packet before a source is expired.")

#define RTP_MAX_DROPOUT_TEXT N_("Maximum RTP sequence number dropout")
#define RTP_MAX_DROPOUT_LONGTEXT N_( \
    "RTP packets will be discarded if they are too much ahead (i.e. in the " \
    "future) by this many packets from the last received packet." )

#define RTP_MAX_MISORDER_TEXT N_("Maximum RTP sequence number misordering")
#define RTP_MAX_MISORDER_LONGTEXT N_( \
    "RTP packets will be discarded if they are too far behind (i.e. in the " \
    "past) by this many packets from the last received packet." )

static int  Open (vlc_object_t *);
static void Close (vlc_object_t *);

/*
 * Module descriptor
 */
vlc_module_begin ();
    set_shortname (_("RTP"));
    set_description (_("(Experimental) Real-Time Protocol demuxer"));
    set_category (CAT_INPUT);
    set_subcategory (SUBCAT_INPUT_DEMUX);
    set_capability ("access_demux", 0);
    set_callbacks (Open, Close);

    add_integer ("rtp-caching", 1000, NULL, RTP_CACHING_TEXT,
                 RTP_CACHING_LONGTEXT, true);
        change_integer_range (0, 65535);
    add_string ("srtp-key", "", NULL,
                SRTP_KEY_TEXT, SRTP_KEY_LONGTEXT, false);
    add_string ("srtp-salt", "", NULL,
                SRTP_SALT_TEXT, SRTP_SALT_LONGTEXT, false);
    add_integer ("rtp-max-src", 1, NULL, RTP_MAX_SRC_TEXT,
                 RTP_MAX_SRC_LONGTEXT, true);
        change_integer_range (1, 255);
    add_integer ("rtp-timeout", 5, NULL, RTP_TIMEOUT_TEXT,
                 RTP_TIMEOUT_LONGTEXT, true);
    add_integer ("rtp-max-dropout", 3000, NULL, RTP_MAX_DROPOUT_TEXT,
                 RTP_MAX_DROPOUT_LONGTEXT, true);
        change_integer_range (0, 32767);
    add_integer ("rtp-max-misorder", 100, NULL, RTP_MAX_MISORDER_TEXT,
                 RTP_MAX_MISORDER_LONGTEXT, true);
        change_integer_range (0, 32767);

    add_shortcut ("dccp");
    /*add_shortcut ("sctp");*/
    add_shortcut ("rtptcp"); /* "tcp" is already taken :( */
    add_shortcut ("rtp");
    add_shortcut ("udplite");
vlc_module_end ();

/*
 * TODO: so much stuff
 * - send RTCP-RR and RTCP-BYE
 * - dynamic payload types (need SDP parser)
 * - multiple medias (need SDP parser, and RTCP-SR parser for lip-sync)
 * - support for access_filter in case of stream_Demux (MPEG-TS)
 */

#ifndef IPPROTO_DCCP
# define IPPROTO_DCCP 33 /* IANA */
#endif

#ifndef IPPROTO_UDPLITE
# define IPPROTO_UDPLITE 136 /* from IANA */
#endif


/*
 * Local prototypes
 */
static int Demux (demux_t *);
static int Control (demux_t *, int i_query, va_list args);
static int extract_port (char **phost);

/**
 * Probes and initializes.
 */
static int Open (vlc_object_t *obj)
{
    demux_t *demux = (demux_t *)obj;
    int tp; /* transport protocol */

    if (!strcmp (demux->psz_access, "dccp"))
        tp = IPPROTO_DCCP;
    else
    if (!strcmp (demux->psz_access, "rtptcp"))
        tp = IPPROTO_TCP;
    else
    if (!strcmp (demux->psz_access, "rtp"))
        tp = IPPROTO_UDP;
    else
    if (!strcmp (demux->psz_access, "udplite"))
        tp = IPPROTO_UDPLITE;
    else
        return VLC_EGENERIC;

    char *tmp = strdup (demux->psz_path);
    char *shost = tmp;
    if (shost == NULL)
        return VLC_ENOMEM;

    char *dhost = strchr (shost, '@');
    if (dhost)
        *dhost++ = '\0';

    /* Parses the port numbers */
    int sport = 0, dport = 0;
    sport = extract_port (&shost);
    if (dhost != NULL)
        dport = extract_port (&dhost);
    if (dport == 0)
        dport = 5004; /* avt-profile-1 port */

    /* Try to connect */
    int fd = -1, rtcp_fd = -1;

    switch (tp)
    {
        case IPPROTO_UDP:
        case IPPROTO_UDPLITE:
            fd = net_OpenDgram (obj, dhost, (dport + 1) & ~1,
                                shost, (sport + 1) & ~1, AF_UNSPEC, tp);
            if (fd == -1)
                break;
            rtcp_fd = net_OpenDgram (obj, dhost, dport | 1, shost,
                                     sport ? (sport | 1) : 0, AF_UNSPEC, tp);
            break;

         case IPPROTO_DCCP:
#ifndef SOCK_DCCP /* provisional API (FIXME) */
# ifdef __linux__
#  define SOCK_DCCP 6
# endif
#endif
#ifdef SOCK_DCCP
            var_Create (obj, "dccp-service", VLC_VAR_STRING);
            var_SetString (obj, "dccp-service", "RTPV"); /* FIXME: RTPA? */
            fd = net_Connect (obj, shost, (sport + 1) & ~1, SOCK_DCCP, tp);
#else
            msg_Err (obj, "DCCP support not included");
#endif
            break;

        case IPPROTO_TCP:
            fd = net_Connect (obj, shost, (sport + 1) & ~1, SOCK_STREAM, tp);
            break;
    }

    free (tmp);
    if (fd == -1)
        return VLC_EGENERIC;
    net_SetCSCov (fd, -1, 12);

    /* Initializes demux */
    demux_sys_t *p_sys = malloc (sizeof (*p_sys));
    if (p_sys == NULL)
    {
        net_Close (fd);
        if (rtcp_fd != -1)
            net_Close (rtcp_fd);
        return VLC_EGENERIC;
    }

    p_sys->srtp         = NULL;
    p_sys->fd           = fd;
    p_sys->rtcp_fd      = rtcp_fd;
    p_sys->caching      = var_CreateGetInteger (obj, "rtp-caching");
    p_sys->max_src      = var_CreateGetInteger (obj, "rtp-max-src");
    p_sys->timeout      = var_CreateGetInteger (obj, "rtp-timeout");
    p_sys->max_dropout  = var_CreateGetInteger (obj, "rtp-max-dropout");
    p_sys->max_misorder = var_CreateGetInteger (obj, "rtp-max-misorder");
    p_sys->autodetect   = true;
    p_sys->framed_rtp   = (tp == IPPROTO_TCP);

    demux->pf_demux   = Demux;
    demux->pf_control = Control;
    demux->p_sys      = p_sys;

    p_sys->session = rtp_session_create (demux);
    if (p_sys->session == NULL)
        goto error;

    char *key = var_CreateGetNonEmptyString (demux, "srtp-key");
    if (key)
    {
        p_sys->srtp = srtp_create (SRTP_ENCR_AES_CM, SRTP_AUTH_HMAC_SHA1, 10,
                                   SRTP_PRF_AES_CM, SRTP_RCC_MODE1);
        if (p_sys->srtp == NULL)
        {
            free (key);
            goto error;
        }

        char *salt = var_CreateGetNonEmptyString (demux, "srtp-salt");
        errno = srtp_setkeystring (p_sys->srtp, key, salt ? salt : "");
        free (salt);
        free (key);
        if (errno)
        {
            msg_Err (obj, "bad SRTP key/salt combination (%m)");
            goto error;
        }
    }

    return VLC_SUCCESS;

error:
    Close (obj);
    return VLC_EGENERIC;
}


/**
 * Releases resources
 */
static void Close (vlc_object_t *obj)
{
    demux_t *demux = (demux_t *)obj;
    demux_sys_t *p_sys = demux->p_sys;

    if (p_sys->srtp)
        srtp_destroy (p_sys->srtp);
    if (p_sys->session)
        rtp_session_destroy (demux, p_sys->session);
    if (p_sys->rtcp_fd != -1)
        net_Close (p_sys->rtcp_fd);
    net_Close (p_sys->fd);
    free (p_sys);
}


/**
 * Extracts port number from "[host]:port" or "host:port" strings,
 * and remove brackets from the host name.
 * @param phost pointer to the string upon entry,
 * pointer to the hostname upon return.
 * @return port number, 0 if missing.
 */
static int extract_port (char **phost)
{
    char *host = *phost, *port;

    if (host[0] == '[')
    {
        host = *++phost; /* skip '[' */
        port = strchr (host, ']');
        if (port)
            *port++ = '\0'; /* skip ']' */
    }
    else
        port = strchr (host, ':');

    if (port == NULL)
        return 0;
    *port++ = '\0'; /* skip ':' */
    return atoi (port);
}


/**
 * Control callback
 */
static int Control (demux_t *demux, int i_query, va_list args)
{
    demux_sys_t *p_sys = demux->p_sys;

    switch (i_query)
    {
        case DEMUX_GET_POSITION:
        {
            float *v = va_arg (args, float *);
            *v = 0.;
            return 0;
        }

        case DEMUX_GET_LENGTH:
        case DEMUX_GET_TIME:
        {
            int64_t *v = va_arg (args, int64_t *);
            *v = 0;
            return 0;
        }

        case DEMUX_GET_PTS_DELAY:
        {
            int64_t *v = va_arg (args, int64_t *);
            *v = p_sys->caching;
            return 0;
        }
    }

    return VLC_EGENERIC;
}


/**
 * Checks if a file descriptor is hung up.
 */
static bool fd_dead (int fd)
{
    struct pollfd ufd = { .fd = fd, };

    return (poll (&ufd, 1, 0) == 1) && (ufd.revents & POLLHUP);
}


/**
 * Gets a datagram from the network, or NULL in case of fatal error.
 */
static block_t *rtp_dgram_recv (demux_t *demux, int fd)
{
    block_t *block = block_Alloc (0xffff);
    ssize_t len;

    do
    {
        len = net_Read (VLC_OBJECT (demux), fd, NULL,
                                block->p_buffer, block->i_buffer, false);
        if (((len <= 0) && fd_dead (fd))
         || !vlc_object_alive (demux))
        {
            block_Release (block);
            return NULL;
        }
    }
    while (len == -1);

    return block_Realloc (block, 0, len);
}

/**
 * Gets a framed RTP packet, or NULL in case of fatal error.
 */
static block_t *rtp_stream_recv (demux_t *demux, int fd)
{
    ssize_t len = 0;
    uint8_t hdr[2]; /* frame header */

    /* Receives the RTP frame header */
    do
    {
        ssize_t val = net_Read (VLC_OBJECT (demux), fd, NULL,
                                hdr + len, 2 - len, false);
        if (val <= 0)
            return NULL;
        len += val;
    }
    while (len < 2);

    block_t *block = block_Alloc (GetWBE (hdr));

    /* Receives the RTP packet */
    for (ssize_t i = 0; i < len;)
    {
        ssize_t val;

        val = net_Read (VLC_OBJECT (demux), fd, NULL,
                        block->p_buffer + i, block->i_buffer - i, false);
        if (val <= 0)
        {
            block_Release (block);
            return NULL;
        }
        i += val;
    }

    return block;
}


/*
 * Generic packet handlers
 */

static void *codec_init (demux_t *demux, es_format_t *fmt)
{
    return es_out_Add (demux->out, fmt);
}

static void codec_destroy (demux_t *demux, void *data)
{
    if (data)
        es_out_Del (demux->out, (es_out_id_t *)data);
}

/* Send a packet to decoder */
static void codec_decode (demux_t *demux, void *data, block_t *block)
{
    if (data)
    {
        block->i_dts = 0; /* RTP does not specify this */
        es_out_Control (demux->out, ES_OUT_SET_PCR,
                        block->i_pts - demux->p_sys->caching * 1000);
        es_out_Send (demux->out, (es_out_id_t *)data, block);
    }
    else
        block_Release (block);
}


static void *stream_init (demux_t *demux, const char *name)
{
    return stream_DemuxNew (demux, name, demux->out);
}

static void stream_destroy (demux_t *demux, void *data)
{
    if (data)
        stream_DemuxDelete ((stream_t *)data);
    (void)demux;
}

/* Send a packet to a chained demuxer */
static void stream_decode (demux_t *demux, void *data, block_t *block)
{
    if (data)
        stream_DemuxSend ((stream_t *)data, block);
    else
        block_Release (block);
    (void)demux;
}

/*
 * Static payload types handler
 */

/* PT=0
 * PCMU: G.711 µ-law (RFC3551)
 */
static void *pcmu_init (demux_t *demux)
{
    es_format_t fmt;

    es_format_Init (&fmt, AUDIO_ES, VLC_FOURCC ('u', 'l', 'a', 'w'));
    fmt.audio.i_rate = 8000;
    fmt.audio.i_channels = 1;
    return codec_init (demux, &fmt);
}

/* PT=8
 * PCMA: G.711 A-law (RFC3551)
 */
static void *pcma_init (demux_t *demux)
{
    es_format_t fmt;

    es_format_Init (&fmt, AUDIO_ES, VLC_FOURCC ('a', 'l', 'a', 'w'));
    fmt.audio.i_rate = 8000;
    fmt.audio.i_channels = 1;
    return codec_init (demux, &fmt);
}

/* PT=10,11
 * L16: 16-bits (network byte order) PCM
 */
static void *l16s_init (demux_t *demux)
{
    es_format_t fmt;

    es_format_Init (&fmt, AUDIO_ES, VLC_FOURCC ('s', '1', '6', 'b'));
    fmt.audio.i_rate = 44100;
    fmt.audio.i_channels = 2;
    return codec_init (demux, &fmt);
}

static void *l16m_init (demux_t *demux)
{
    es_format_t fmt;

    es_format_Init (&fmt, AUDIO_ES, VLC_FOURCC ('s', '1', '6', 'b'));
    fmt.audio.i_rate = 44100;
    fmt.audio.i_channels = 1;
    return codec_init (demux, &fmt);
}

/* PT=14
 * MPA: MPEG Audio (RFC2250, §3.4)
 */
static void *mpa_init (demux_t *demux)
{
    es_format_t fmt;

    es_format_Init (&fmt, AUDIO_ES, VLC_FOURCC ('m', 'p', 'g', 'a'));
    fmt.audio.i_channels = 2;
    return codec_init (demux, &fmt);
}

static void mpa_decode (demux_t *demux, void *data, block_t *block)
{
    if (block->i_buffer < 4)
    {
        block_Release (block);
        return;
    }

    block->i_buffer -= 4; /* 32-bits RTP/MPA header */
    block->p_buffer += 4;

    codec_decode (demux, data, block);
}


/* PT=32
 * MPV: MPEG Video (RFC2250, §3.5)
 */
static void *mpv_init (demux_t *demux)
{
    es_format_t fmt;

    es_format_Init (&fmt, VIDEO_ES, VLC_FOURCC ('m', 'p', 'g', 'v'));
    return codec_init (demux, &fmt);
}

static void mpv_decode (demux_t *demux, void *data, block_t *block)
{
    if (block->i_buffer < 4)
    {
        block_Release (block);
        return;
    }

    block->i_buffer -= 4; /* 32-bits RTP/MPV header */
    block->p_buffer += 4;
#if 0
    if (block->p_buffer[-3] & 0x4)
    {
        /* MPEG2 Video extension header */
        /* TODO: shouldn't we skip this too ? */
    }
#endif
    codec_decode (demux, data, block);
}


/* PT=33
 * MP2: MPEG TS (RFC2250, §2)
 */
static void *ts_init (demux_t *demux)
{
    return stream_init (demux, "ts");
}


/*
 * Dynamic payload type handlers
 * Hmm, none implemented yet.
 */

/**
 * Processing callback
 */
static int Demux (demux_t *demux)
{
    demux_sys_t *p_sys = demux->p_sys;
    block_t     *block;

    block = p_sys->framed_rtp
        ? rtp_stream_recv (demux, p_sys->fd)
        : rtp_dgram_recv (demux, p_sys->fd);
    if (!block)
        return 0;

    if (block->i_buffer < 2)
        goto drop;

    const uint8_t ptype = block->p_buffer[1] & 0x7F;
    if (ptype >= 72 && ptype <= 76)
        goto drop; /* Muxed RTCP, ignore for now */

    if (p_sys->srtp)
    {
        size_t len = block->i_buffer;
        if (srtp_recv (p_sys->srtp, block->p_buffer, &len))
        {
            msg_Dbg (demux, "SRTP authentication/decryption failed");
            goto drop;
        }
        block->i_buffer = len;
    }

    /* Not using SDP, we need to guess the payload format used */
    /* see http://www.iana.org/assignments/rtp-parameters */
    if (p_sys->autodetect)
    {
        rtp_pt_t pt = {
            .init = NULL,
            .destroy = codec_destroy,
            .decode = codec_decode,
            .frequency = 0,
            .number = ptype,
        };
        switch (ptype)
        {
          case 0:
            msg_Dbg (demux, "detected G.711 mu-law");
            pt.init = pcmu_init;
            pt.frequency = 8000;
            break;

          case 8:
            msg_Dbg (demux, "detected G.711 A-law");
            pt.init = pcma_init;
            pt.frequency = 8000;
            break;

          case 10:
            msg_Dbg (demux, "detected stereo PCM");
            pt.init = l16s_init;
            pt.frequency = 44100;
            break;

          case 11:
            msg_Dbg (demux, "detected mono PCM");
            pt.init = l16m_init;
            pt.frequency = 44100;
            break;

          case 14:
            msg_Dbg (demux, "detected MPEG Audio");
            pt.init = mpa_init;
            pt.decode = mpa_decode;
            pt.frequency = 90000;
            break;

          case 32:
            msg_Dbg (demux, "detected MPEG Video");
            pt.init = mpv_init;
            pt.decode = mpv_decode;
            pt.frequency = 90000;
            break;

          case 33:
            msg_Dbg (demux, "detected MPEG2 TS");
            pt.init = ts_init;
            pt.destroy = stream_destroy;
            pt.decode = stream_decode;
            pt.frequency = 90000;
            break;

          default:
            goto drop;
        }
        rtp_add_type (demux, p_sys->session, &pt);
        p_sys->autodetect = false;
    }
    rtp_receive (demux, p_sys->session, block);

    return 1;
drop:
    block_Release (block);
    return 1;
}