root/modules/demux/rtpxiph.c

/**
 * @file rtpxiph.c
 * @brief Real-Time Protocol (RTP) Xiph payloads receival
 */
/*****************************************************************************
 * Copyright © 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>

/* PT=dynamic
 * vorbis: Xiph Vorbis audio (draft-ietf-avt-rtp-vorbis-09, RFC FIXME)
 */
typedef struct rtp_vorbis_t
{
    es_out_id_t *id;
    block_t     *block;
    uint32_t     ident;
} rtp_vorbis_t;

static void *vorbis_init (demux_t *demux)
{
    rtp_vorbis_t *self = malloc (sizeof (*self));

    if (self == NULL)
        return NULL;

    self->id = NULL;
    self->block = NULL;
    self->ident = 0xffffffff; /* impossible value on the wire */
    (void)demux;
    return self;
}

static void vorbis_destroy (demux_t *demux, void *data)
{
    rtp_vorbis_t *self = data;

    if (!data)
        return;
    if (self->block)
    {
        self->block->i_flags |= BLOCK_FLAG_CORRUPTED;
        codec_decode (demux, self->id, self->block);
    }
    codec_destroy (demux, self->id);
    free (self);
}

/* Convert configuration from RTP to VLC format */
static ssize_t vorbis_header (void **pextra, const uint8_t *buf, size_t len)
{
    /* Headers number */
    if (len == 0)
          return -1; /* Invalid */
    unsigned hcount = 1 + *buf++;
    len--;
    if (hcount != 3)
          return -1; /* Invalid */

    /* Header lengths */
    uint16_t idlen = 0, cmtlen = 0, setuplen = 0;
    do
    {
        if (len == 0)
            return -1;
        idlen = (idlen << 7) | (*buf & 0x7f);
        len--;
    }
    while (*buf++ & 0x80);
    do
    {
        if (len == 0)
            return -1;
        cmtlen = (cmtlen << 7) | (*buf & 0x7f);
        len--;
    }
    while (*buf++ & 0x80);
    if (len < idlen + cmtlen)
        return -1;
    setuplen = len - (idlen + cmtlen);

    /* Create the VLC extra format header */
    uint8_t *extra = malloc ((size_t)6 + idlen + cmtlen + setuplen);
    if (extra == NULL)
        return -1;
    uint8_t *ptr = *pextra = extra;
    /* Identification header */
    *ptr++ = idlen >> 8;
    *ptr++ = idlen & 0xff;
    memcpy (ptr, buf, idlen);
    buf += idlen;
    ptr += idlen;
    /* Comments header */
    *ptr++ = cmtlen >> 8;
    *ptr++ = cmtlen & 0xff;
    memcpy (ptr, buf, cmtlen);
    buf += cmtlen;
    ptr += cmtlen;
    /* Setup header */
    *ptr++ = setuplen >> 8;
    *ptr++ = setuplen & 0xff;
    memcpy (ptr, buf, setuplen);
    ptr += setuplen;
    return ptr - extra;
}


static void vorbis_decode (demux_t *demux, void *data, block_t *block)
{
    rtp_vorbis_t *self = data;

    if (!data || block->i_buffer < 4)
        goto drop;

    /* 32-bits Vorbis RTP header (§2.2) */
    uint32_t ident = GetDWBE (block->p_buffer);
    block->i_buffer -= 4;
    block->p_buffer += 4;

    unsigned fragtype = (ident >> 6) & 3;
    unsigned datatype = (ident >> 4) & 3;
    unsigned pkts = (ident) & 15;
    ident >>= 8;

    /* Vorbis RTP defragmentation */
    if (self->block && (block->i_flags & BLOCK_FLAG_DISCONTINUITY))
    {   /* Screwed! discontinuity within a fragmented packet */
        msg_Warn (demux, "discontinuity in fragmented Vorbis packet");
        block_Release (self->block);
        self->block = NULL;
    }

    if (fragtype <= 1)
    {
        if (self->block) /* Invalid first fragment */
        {
            block_Release (self->block);
            self->block = NULL;
        }
    }
    else
    {
        if (!self->block)
            goto drop; /* Invalid non-first fragment */
    }

    if (fragtype > 0)
    {   /* Fragment */
        if (pkts > 0 || block->i_buffer < 2)
            goto drop;

        size_t fraglen = GetWBE (block->p_buffer);
        if (block->i_buffer < (fraglen + 2))
            goto drop; /* Invalid payload length */
        block->i_buffer = fraglen;
        if (fragtype == 1)/* Keep first fragment */
        {
            block->i_buffer += 2;
            self->block = block;
        }
        else
        {   /* Append non-first fragment */
            size_t len = self->block->i_buffer;
            self->block = block_Realloc (self->block, 0, len + fraglen);
            if (!self->block)
            {
                block_Release (block);
                return;
            }
            memcpy (self->block->p_buffer + len, block->p_buffer + 2,
                    fraglen);
            block_Release (block);
        }
        if (fragtype < 3)
            return; /* Non-last fragment */

        /* Last fragment reached, process it */
        block = self->block;
        self->block = NULL;
        SetWBE (block->p_buffer, block->i_buffer - 2);
        pkts = 1;
    }

    /* Vorbis RTP payload packets processing */
    while (pkts > 0)
    {
        if (block->i_buffer < 2)
            goto drop;

        size_t len = GetWBE (block->p_buffer);
        block->i_buffer -= 2;
        block->p_buffer += 2;
        if (block->i_buffer < len)
            goto drop;

        switch (datatype)
        {
            case 0: /* Raw audio frame */
            {
                if (self->ident != ident)
                    break; /* Ignore raw without configuration */
                block_t *raw = block_Alloc (len);
                memcpy (raw->p_buffer, block->p_buffer, len);
                raw->i_pts = block->i_pts; /* FIXME: what about pkts > 1 */
                codec_decode (demux, self->id, raw);
                break;
            }

            case 1: /* Packed configuration frame (§3.1.1) */
            {
                if (self->ident == ident)
                    break; /* Ignore config retransmission */

                void *extv;
                ssize_t extc = vorbis_header (&extv, block->p_buffer, len);
                if (extc < 0)
                    break;

                es_format_t fmt;
                es_format_Init (&fmt, AUDIO_ES, VLC_FOURCC ('v','o','r','b'));
                fmt.p_extra = extv;
                fmt.i_extra = extc;
                codec_destroy (demux, self->id);
                msg_Dbg (demux, "Vorbis packed configuration received "
                         "(%06"PRIx32")", ident);
                self->ident = ident;
                self->id = codec_init (demux, &fmt);
                break;
            }
        }

        block->i_buffer -= len;
        block->p_buffer += len;
        pkts--;
    }

drop:
    block_Release (block);
}