FFmpeg/libavformat/oma.c

/*
 * Sony OpenMG (OMA) demuxer
 *
 * Copyright (c) 2008 Maxim Poliakovski
 *               2008 Benjamin Larsson
 *               2011 David Goldwich
 *
 * This file is part of Libav.
 *
 * Libav 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.
 *
 * Libav 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 Libav; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

/**
 * @file
 * This is a demuxer for Sony OpenMG Music files
 *
 * Known file extensions: ".oma", "aa3"
 * The format of such files consists of three parts:
 * - "ea3" header carrying overall info and metadata. Except for starting with
 *   "ea" instead of "ID", it's an ID3v2 header.
 * - "EA3" header is a Sony-specific header containing information about
 *   the OpenMG file: codec type (usually ATRAC, can also be MP3 or WMA),
 *   codec specific info (packet size, sample rate, channels and so on)
 *   and DRM related info (file encryption, content id).
 * - Sound data organized in packets follow the EA3 header
 *   (can be encrypted using the Sony DRM!).
 *
 * CODEC SUPPORT: Only ATRAC3 codec is currently supported!
 */

#include "avformat.h"
#include "libavutil/intreadwrite.h"
#include "libavutil/des.h"
#include "pcm.h"
#include "riff.h"
#include "id3v2.h"

#define EA3_HEADER_SIZE 96
#define ID3v2_EA3_MAGIC "ea3"
#define OMA_ENC_HEADER_SIZE 16

enum {
    OMA_CODECID_ATRAC3  = 0,
    OMA_CODECID_ATRAC3P = 1,
    OMA_CODECID_MP3     = 3,
    OMA_CODECID_LPCM    = 4,
    OMA_CODECID_WMA     = 5,
};

static const AVCodecTag codec_oma_tags[] = {
    { CODEC_ID_ATRAC3,  OMA_CODECID_ATRAC3 },
    { CODEC_ID_ATRAC3P, OMA_CODECID_ATRAC3P },
    { CODEC_ID_MP3,     OMA_CODECID_MP3 },
};

static const uint64_t leaf_table[] = {
    0xd79e8283acea4620, 0x7a9762f445afd0d8,
    0x354d60a60b8c79f1, 0x584e1cde00b07aee,
    0x1573cd93da7df623, 0x47f98d79620dd535
};

typedef struct OMAContext {
    uint64_t content_start;
    int encrypted;
    uint16_t k_size;
    uint16_t e_size;
    uint16_t i_size;
    uint16_t s_size;
    uint32_t rid;
    uint8_t r_val[24];
    uint8_t n_val[24];
    uint8_t m_val[8];
    uint8_t s_val[8];
    uint8_t sm_val[8];
    uint8_t e_val[8];
    uint8_t iv[8];
    struct AVDES av_des;
} OMAContext;

static void hex_log(AVFormatContext *s, int level, const char *name, const uint8_t *value, int len)
{
    char buf[33];
    len = FFMIN(len, 16);
    if (av_log_get_level() < level)
        return;
    ff_data_to_hex(buf, value, len, 1);
    buf[len<<1] = '\0';
    av_log(s, level, "%s: %s\n", name, buf);
}

static int kset(AVFormatContext *s, const uint8_t *r_val, const uint8_t *n_val, int len)
{
    OMAContext *oc = s->priv_data;

    if (!r_val && !n_val)
        return -1;

    len = FFMIN(len, 16);

    /* use first 64 bits in the third round again */
    if (r_val) {
        if (r_val != oc->r_val) {
            memset(oc->r_val, 0, 24);
            memcpy(oc->r_val, r_val, len);
        }
        memcpy(&oc->r_val[16], r_val, 8);
    }
    if (n_val) {
        if (n_val != oc->n_val) {
            memset(oc->n_val, 0, 24);
            memcpy(oc->n_val, n_val, len);
        }
        memcpy(&oc->n_val[16], n_val, 8);
    }

    return 0;
}

static int rprobe(AVFormatContext *s, uint8_t *enc_header, const uint8_t *r_val)
{
    OMAContext *oc = s->priv_data;
    unsigned int pos;
    struct AVDES av_des;

    if (!enc_header || !r_val)
        return -1;

    /* m_val */
    av_des_init(&av_des, r_val, 192, 1);
    av_des_crypt(&av_des, oc->m_val, &enc_header[48], 1, NULL, 1);

    /* s_val */
    av_des_init(&av_des, oc->m_val, 64, 0);
    av_des_crypt(&av_des, oc->s_val, NULL, 1, NULL, 0);

    /* sm_val */
    pos = OMA_ENC_HEADER_SIZE + oc->k_size + oc->e_size;
    av_des_init(&av_des, oc->s_val, 64, 0);
    av_des_mac(&av_des, oc->sm_val, &enc_header[pos], (oc->i_size >> 3));

    pos += oc->i_size;

    return memcmp(&enc_header[pos], oc->sm_val, 8) ? -1 : 0;
}

static int nprobe(AVFormatContext *s, uint8_t *enc_header, const uint8_t *n_val)
{
    OMAContext *oc = s->priv_data;
    uint32_t pos, taglen, datalen;
    struct AVDES av_des;

    if (!enc_header || !n_val)
        return -1;

    pos = OMA_ENC_HEADER_SIZE + oc->k_size;
    if (!memcmp(&enc_header[pos], "EKB ", 4))
        pos += 32;

    if (AV_RB32(&enc_header[pos]) != oc->rid)
        av_log(s, AV_LOG_DEBUG, "Mismatching RID\n");

    taglen = AV_RB32(&enc_header[pos+32]);
    datalen = AV_RB32(&enc_header[pos+36]) >> 4;

    pos += 44 + taglen;

    av_des_init(&av_des, n_val, 192, 1);
    while (datalen-- > 0) {
        av_des_crypt(&av_des, oc->r_val, &enc_header[pos], 2, NULL, 1);
        kset(s, oc->r_val, NULL, 16);
        if (!rprobe(s, enc_header, oc->r_val))
            return 0;
        pos += 16;
    }

    return -1;
}

static int decrypt_init(AVFormatContext *s, ID3v2ExtraMeta *em, uint8_t *header)
{
    OMAContext *oc = s->priv_data;
    ID3v2ExtraMetaGEOB *geob = NULL;
    uint8_t *gdata;

    oc->encrypted = 1;
    av_log(s, AV_LOG_INFO, "File is encrypted\n");

    /* find GEOB metadata */
    while (em) {
        if (!strcmp(em->tag, "GEOB") &&
            (geob = em->data) &&
            !strcmp(geob->description, "OMG_LSI") ||
            !strcmp(geob->description, "OMG_BKLSI")) {
            break;
        }
        em = em->next;
    }
    if (!em) {
        av_log(s, AV_LOG_ERROR, "No encryption header found\n");
        return -1;
    }

    if (geob->datasize < 64) {
        av_log(s, AV_LOG_ERROR, "Invalid GEOB data size: %u\n", geob->datasize);
        return -1;
    }

    gdata = geob->data;

    if (AV_RB16(gdata) != 1)
        av_log(s, AV_LOG_WARNING, "Unknown version in encryption header\n");

    oc->k_size = AV_RB16(&gdata[2]);
    oc->e_size = AV_RB16(&gdata[4]);
    oc->i_size = AV_RB16(&gdata[6]);
    oc->s_size = AV_RB16(&gdata[8]);

    if (memcmp(&gdata[OMA_ENC_HEADER_SIZE], "KEYRING     ", 12)) {
        av_log(s, AV_LOG_ERROR, "Invalid encryption header\n");
        return -1;
    }
    oc->rid = AV_RB32(&gdata[OMA_ENC_HEADER_SIZE + 28]);
    av_log(s, AV_LOG_DEBUG, "RID: %.8x\n", oc->rid);

    memcpy(oc->iv, &header[0x58], 8);
    hex_log(s, AV_LOG_DEBUG, "IV", oc->iv, 8);

    hex_log(s, AV_LOG_DEBUG, "CBC-MAC", &gdata[OMA_ENC_HEADER_SIZE+oc->k_size+oc->e_size+oc->i_size], 8);

    if (s->keylen > 0) {
        kset(s, s->key, s->key, s->keylen);
    }
    if (!memcmp(oc->r_val, (const uint8_t[8]){0}, 8) ||
        rprobe(s, gdata, oc->r_val) < 0 &&
        nprobe(s, gdata, oc->n_val) < 0) {
        int i;
        for (i = 0; i < sizeof(leaf_table); i += 2) {
            uint8_t buf[16];
            AV_WL64(buf, leaf_table[i]);
            AV_WL64(&buf[8], leaf_table[i+1]);
            kset(s, buf, buf, 16);
            if (!rprobe(s, gdata, oc->r_val) || !nprobe(s, gdata, oc->n_val))
                break;
        }
        if (i >= sizeof(leaf_table)) {
            av_log(s, AV_LOG_ERROR, "Invalid key\n");
            return -1;
        }
    }

    /* e_val */
    av_des_init(&oc->av_des, oc->m_val, 64, 0);
    av_des_crypt(&oc->av_des, oc->e_val, &gdata[OMA_ENC_HEADER_SIZE + 40], 1, NULL, 0);
    hex_log(s, AV_LOG_DEBUG, "EK", oc->e_val, 8);

    /* init e_val */
    av_des_init(&oc->av_des, oc->e_val, 64, 1);

    return 0;
}

static int oma_read_header(AVFormatContext *s,
                           AVFormatParameters *ap)
{
    static const uint16_t srate_tab[6] = {320,441,480,882,960,0};
    int     ret, framesize, jsflag, samplerate;
    uint32_t codec_params;
    int16_t eid;
    uint8_t buf[EA3_HEADER_SIZE];
    uint8_t *edata;
    AVStream *st;
    ID3v2ExtraMeta *extra_meta = NULL;
    OMAContext *oc = s->priv_data;

    ff_id3v2_read_all(s, ID3v2_EA3_MAGIC, &extra_meta);
    ret = avio_read(s->pb, buf, EA3_HEADER_SIZE);
    if (ret < EA3_HEADER_SIZE)
        return -1;

    if (memcmp(buf, ((const uint8_t[]){'E', 'A', '3'}),3) || buf[4] != 0 || buf[5] != EA3_HEADER_SIZE) {
        av_log(s, AV_LOG_ERROR, "Couldn't find the EA3 header !\n");
        return -1;
    }

    oc->content_start = avio_tell(s->pb);

    /* encrypted file */
    eid = AV_RB16(&buf[6]);
    if (eid != -1 && eid != -128 && decrypt_init(s, extra_meta, buf) < 0) {
        ff_id3v2_free_extra_meta(&extra_meta);
        return -1;
    }

    ff_id3v2_free_extra_meta(&extra_meta);

    codec_params = AV_RB24(&buf[33]);

    st = avformat_new_stream(s, NULL);
    if (!st)
        return AVERROR(ENOMEM);

    st->start_time = 0;
    st->codec->codec_type  = AVMEDIA_TYPE_AUDIO;
    st->codec->codec_tag   = buf[32];
    st->codec->codec_id    = ff_codec_get_id(codec_oma_tags, st->codec->codec_tag);

    switch (buf[32]) {
        case OMA_CODECID_ATRAC3:
            samplerate = srate_tab[(codec_params >> 13) & 7]*100;
            if (samplerate != 44100)
                av_log_ask_for_sample(s, "Unsupported sample rate: %d\n",
                                      samplerate);

            framesize = (codec_params & 0x3FF) * 8;
            jsflag = (codec_params >> 17) & 1; /* get stereo coding mode, 1 for joint-stereo */
            st->codec->channels    = 2;
            st->codec->sample_rate = samplerate;
            st->codec->bit_rate    = st->codec->sample_rate * framesize * 8 / 1024;

            /* fake the atrac3 extradata (wav format, makes stream copy to wav work) */
            st->codec->extradata_size = 14;
            edata = av_mallocz(14 + FF_INPUT_BUFFER_PADDING_SIZE);
            if (!edata)
                return AVERROR(ENOMEM);

            st->codec->extradata = edata;
            AV_WL16(&edata[0],  1);             // always 1
            AV_WL32(&edata[2],  samplerate);    // samples rate
            AV_WL16(&edata[6],  jsflag);        // coding mode
            AV_WL16(&edata[8],  jsflag);        // coding mode
            AV_WL16(&edata[10], 1);             // always 1
            // AV_WL16(&edata[12], 0);          // always 0

            av_set_pts_info(st, 64, 1, st->codec->sample_rate);
            break;
        case OMA_CODECID_ATRAC3P:
            st->codec->channels = (codec_params >> 10) & 7;
            framesize = ((codec_params & 0x3FF) * 8) + 8;
            st->codec->sample_rate = srate_tab[(codec_params >> 13) & 7]*100;
            st->codec->bit_rate    = st->codec->sample_rate * framesize * 8 / 1024;
            av_set_pts_info(st, 64, 1, st->codec->sample_rate);
            av_log(s, AV_LOG_ERROR, "Unsupported codec ATRAC3+!\n");
            break;
        case OMA_CODECID_MP3:
            st->need_parsing = AVSTREAM_PARSE_FULL;
            framesize = 1024;
            break;
        default:
            av_log(s, AV_LOG_ERROR, "Unsupported codec %d!\n",buf[32]);
            return -1;
    }

    st->codec->block_align = framesize;

    return 0;
}


static int oma_read_packet(AVFormatContext *s, AVPacket *pkt)
{
    OMAContext *oc = s->priv_data;
    int packet_size = s->streams[0]->codec->block_align;
    int ret = av_get_packet(s->pb, pkt, packet_size);

    if (ret <= 0)
        return AVERROR(EIO);

    pkt->stream_index = 0;

    if (oc->encrypted) {
        /* previous unencrypted block saved in IV for the next packet (CBC mode) */
        av_des_crypt(&oc->av_des, pkt->data, pkt->data, (packet_size >> 3), oc->iv, 1);
    }

    return ret;
}

static int oma_read_probe(AVProbeData *p)
{
    const uint8_t *buf;
    unsigned tag_len = 0;

    buf = p->buf;
    /* version must be 3 and flags byte zero */
    if (ff_id3v2_match(buf, ID3v2_EA3_MAGIC) && buf[3] == 3 && !buf[4])
        tag_len = ff_id3v2_tag_len(buf);

    // This check cannot overflow as tag_len has at most 28 bits
    if (p->buf_size < tag_len + 5)
        return 0;

    buf += tag_len;

    if (!memcmp(buf, "EA3", 3) && !buf[4] && buf[5] == EA3_HEADER_SIZE)
        return AVPROBE_SCORE_MAX;
    else
        return 0;
}

static int oma_read_seek(struct AVFormatContext *s, int stream_index, int64_t timestamp, int flags)
{
    OMAContext *oc = s->priv_data;

    pcm_read_seek(s, stream_index, timestamp, flags);

    if (oc->encrypted) {
        /* readjust IV for CBC */
        int64_t pos = avio_tell(s->pb);
        if (pos < oc->content_start)
            memset(oc->iv, 0, 8);
        else {
            if (avio_seek(s->pb, -8, SEEK_CUR) < 0 || avio_read(s->pb, oc->iv, 8) < 8) {
                memset(oc->iv, 0, 8);
                return -1;
            }
        }
    }

    return 0;
}

AVInputFormat ff_oma_demuxer = {
    .name           = "oma",
    .long_name      = NULL_IF_CONFIG_SMALL("Sony OpenMG audio"),
    .priv_data_size = sizeof(OMAContext),
    .read_probe     = oma_read_probe,
    .read_header    = oma_read_header,
    .read_packet    = oma_read_packet,
    .read_seek      = oma_read_seek,
    .flags          = AVFMT_GENERIC_INDEX,
    .extensions     = "oma,omg,aa3",
    .codec_tag      = (const AVCodecTag* const []){codec_oma_tags, 0},
};