/*

 * RTP parser for loss tolerant payload format for MP3 audio (RFC 5219)

 * Copyright (c) 2015 Gilles Chanteperdrix <gch@xenomai.org>

 *

 * This file is part of FFmpeg.

 *

 * FFmpeg is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Lesser General Public

 * License as published by the Free Software Foundation; either

 * version 2.1 of the License, or (at your option) any later version.

 *

 * FFmpeg 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

 * Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public

 * License along with FFmpeg; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

 */

#include "libavutil/attributes.h"

#include "libavutil/intreadwrite.h"

#include "libavutil/mem.h"

#include "avio_internal.h"

#include "rtpdec_formats.h"

struct PayloadContext {

    unsigned adu_size;

    unsigned cur_size;

    uint32_t timestamp;

    uint8_t *split_buf;

    int split_pos, split_buf_size, split_pkts;

    AVIOContext *fragment;

};

static void mpa_robust_close_context(PayloadContext *data)

{

    ffio_free_dyn_buf(&data->fragment);

    av_free(data->split_buf);

}

static int mpa_robust_parse_rtp_header(AVFormatContext *ctx,

                                       const uint8_t *buf, int len,

                                       unsigned *adu_size, unsigned *cont)

{

    unsigned header_size;

    if (len < 2) {

        av_log(ctx, AV_LOG_ERROR, "Invalid %d bytes packet\n", len);

        return AVERROR_INVALIDDATA;

    }

    *cont = !!(buf[0] & 0x80);

    if (!(buf[0] & 0x40)) {

        header_size = 1;

        *adu_size = buf[0] & ~0xc0;

    } else {

        header_size = 2;

        *adu_size = AV_RB16(buf) & ~0xc000;

    }

    return header_size;

}

static int mpa_robust_parse_packet(AVFormatContext *ctx, PayloadContext *data,

                                   AVStream *st, AVPacket *pkt,

                                   uint32_t *timestamp, const uint8_t *buf,

                                   int len, uint16_t seq, int flags)

{

    unsigned adu_size, continuation;

    int err, header_size;

    if (!buf) {

        buf = &data->split_buf[data->split_pos];

        len = data->split_buf_size - data->split_pos;

        header_size = mpa_robust_parse_rtp_header(ctx, buf, len, &adu_size,

                                                  &continuation);

        if (header_size < 0) {

            av_freep(&data->split_buf);

            return header_size;

        }

        buf += header_size;

        len -= header_size;

        if (continuation || adu_size > len) {

            av_freep(&data->split_buf);

            av_log(ctx, AV_LOG_ERROR, "Invalid frame\n");

            return AVERROR_INVALIDDATA;

        }

        if ((err = av_new_packet(pkt, adu_size)) < 0) {

            av_log(ctx, AV_LOG_ERROR, "Out of memory.\n");

            return err;

        }

        pkt->stream_index = st->index;

        memcpy(pkt->data, buf, adu_size);

        data->split_pos += header_size + adu_size;

        if (data->split_pos == data->split_buf_size) {

            av_freep(&data->split_buf);

            return 0;

        }

        return 1;

    }

    header_size = mpa_robust_parse_rtp_header(ctx, buf, len, &adu_size,

                                              &continuation);

    if (header_size < 0)

        return header_size;

    buf += header_size;

    len -= header_size;

    if (!continuation && adu_size <= len) {

        /* One or more complete frames */

        if ((err = av_new_packet(pkt, adu_size)) < 0) {

            av_log(ctx, AV_LOG_ERROR, "Out of memory.\n");

            return err;

        }

        pkt->stream_index = st->index;

        memcpy(pkt->data, buf, adu_size);

        buf += adu_size;

        len -= adu_size;

        if (len) {

            data->split_buf_size = len;

            data->split_buf = av_malloc(data->split_buf_size);

            data->split_pos = 0;

            if (!data->split_buf) {

                av_log(ctx, AV_LOG_ERROR, "Out of memory.\n");

                av_packet_unref(pkt);

                return AVERROR(ENOMEM);

            }

            memcpy(data->split_buf, buf, data->split_buf_size);

            return 1;

        }

        return 0;

    } else if (!continuation) { /* && adu_size > len */

        /* First fragment */

        ffio_free_dyn_buf(&data->fragment);

        data->adu_size = adu_size;

        data->cur_size = len;

        data->timestamp = *timestamp;

        err = avio_open_dyn_buf(&data->fragment);

        if (err < 0)

            return err;

        avio_write(data->fragment, buf, len);

        return AVERROR(EAGAIN);

    }

    /* else continuation == 1 */

    /* Fragment other than first */

    if (!data->fragment) {

        av_log(ctx, AV_LOG_WARNING,

            "Received packet without a start fragment; dropping.\n");

        return AVERROR(EAGAIN);

    }

    if (adu_size != data->adu_size ||

        data->timestamp != *timestamp) {

        ffio_free_dyn_buf(&data->fragment);

        av_log(ctx, AV_LOG_ERROR, "Invalid packet received\n");

        return AVERROR_INVALIDDATA;

    }

    avio_write(data->fragment, buf, len);

    data->cur_size += len;

    if (data->cur_size < data->adu_size)

        return AVERROR(EAGAIN);

    err = ff_rtp_finalize_packet(pkt, &data->fragment, st->index);

    if (err < 0) {

        av_log(ctx, AV_LOG_ERROR,

               "Error occurred when getting fragment buffer.\n");

        return err;

    }

    return 0;

}

const RTPDynamicProtocolHandler ff_mpeg_audio_robust_dynamic_handler = {

    .enc_name          = "mpa-robust",

    .codec_type        = AVMEDIA_TYPE_AUDIO,

    .codec_id          = AV_CODEC_ID_MP3ADU,

    .need_parsing      = AVSTREAM_PARSE_HEADERS,

    .priv_data_size    = sizeof(PayloadContext),

    .close             = mpa_robust_close_context,

    .parse_packet      = mpa_robust_parse_packet,

};