mirror of https://github.com/FFmpeg/FFmpeg.git
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
389 lines
11 KiB
389 lines
11 KiB
/* |
|
* Apple HTTP Live Streaming Sample Encryption/Decryption |
|
* |
|
* Copyright (c) 2021 Nachiket Tarate |
|
* |
|
* 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 |
|
*/ |
|
|
|
/** |
|
* @file |
|
* Apple HTTP Live Streaming Sample Encryption |
|
* https://developer.apple.com/library/ios/documentation/AudioVideo/Conceptual/HLS_Sample_Encryption |
|
*/ |
|
|
|
#include "hls_sample_encryption.h" |
|
|
|
#include "libavcodec/adts_header.h" |
|
#include "libavcodec/adts_parser.h" |
|
#include "libavcodec/ac3_parser_internal.h" |
|
|
|
|
|
typedef struct NALUnit { |
|
uint8_t *data; |
|
int type; |
|
int length; |
|
int start_code_length; |
|
} NALUnit; |
|
|
|
typedef struct AudioFrame { |
|
uint8_t *data; |
|
int length; |
|
int header_length; |
|
} AudioFrame; |
|
|
|
typedef struct CodecParserContext { |
|
const uint8_t *buf_ptr; |
|
const uint8_t *buf_end; |
|
} CodecParserContext; |
|
|
|
static const int eac3_sample_rate_tab[] = { 48000, 44100, 32000, 0 }; |
|
|
|
void ff_hls_senc_read_audio_setup_info(HLSAudioSetupInfo *info, const uint8_t *buf, size_t size) |
|
{ |
|
if (size < 8) |
|
return; |
|
|
|
info->codec_tag = AV_RL32(buf); |
|
|
|
if (info->codec_tag == MKTAG('z','a','a','c')) |
|
info->codec_id = AV_CODEC_ID_AAC; |
|
else if (info->codec_tag == MKTAG('z','a','c','3')) |
|
info->codec_id = AV_CODEC_ID_AC3; |
|
else if (info->codec_tag == MKTAG('z','e','c','3')) |
|
info->codec_id = AV_CODEC_ID_EAC3; |
|
else |
|
info->codec_id = AV_CODEC_ID_NONE; |
|
|
|
buf += 4; |
|
info->priming = AV_RL16(buf); |
|
buf += 2; |
|
info->version = *buf++; |
|
info->setup_data_length = *buf++; |
|
|
|
if (info->setup_data_length > size - 8) |
|
info->setup_data_length = size - 8; |
|
|
|
if (info->setup_data_length > HLS_MAX_AUDIO_SETUP_DATA_LEN) |
|
return; |
|
|
|
memcpy(info->setup_data, buf, info->setup_data_length); |
|
} |
|
|
|
int ff_hls_senc_parse_audio_setup_info(AVStream *st, HLSAudioSetupInfo *info) |
|
{ |
|
int ret = 0; |
|
|
|
st->codecpar->codec_tag = info->codec_tag; |
|
|
|
if (st->codecpar->codec_id == AV_CODEC_ID_AAC) |
|
return 0; |
|
|
|
if (st->codecpar->codec_id != AV_CODEC_ID_AC3 && st->codecpar->codec_id != AV_CODEC_ID_EAC3) |
|
return AVERROR_INVALIDDATA; |
|
|
|
if (st->codecpar->codec_id == AV_CODEC_ID_AC3) { |
|
AC3HeaderInfo *ac3hdr = NULL; |
|
|
|
ret = avpriv_ac3_parse_header(&ac3hdr, info->setup_data, info->setup_data_length); |
|
if (ret < 0) { |
|
if (ret != AVERROR(ENOMEM)) |
|
av_free(ac3hdr); |
|
return ret; |
|
} |
|
|
|
st->codecpar->sample_rate = ac3hdr->sample_rate; |
|
st->codecpar->channels = ac3hdr->channels; |
|
st->codecpar->channel_layout = ac3hdr->channel_layout; |
|
st->codecpar->bit_rate = ac3hdr->bit_rate; |
|
|
|
av_free(ac3hdr); |
|
} else { /* Parse 'dec3' EC3SpecificBox */ |
|
GetBitContext gb; |
|
int data_rate, fscod, acmod, lfeon; |
|
|
|
ret = init_get_bits8(&gb, info->setup_data, info->setup_data_length); |
|
if (ret < 0) |
|
return AVERROR_INVALIDDATA; |
|
|
|
data_rate = get_bits(&gb, 13); |
|
skip_bits(&gb, 3); |
|
fscod = get_bits(&gb, 2); |
|
skip_bits(&gb, 10); |
|
acmod = get_bits(&gb, 3); |
|
lfeon = get_bits(&gb, 1); |
|
|
|
st->codecpar->sample_rate = eac3_sample_rate_tab[fscod]; |
|
|
|
st->codecpar->channel_layout = avpriv_ac3_channel_layout_tab[acmod]; |
|
if (lfeon) |
|
st->codecpar->channel_layout |= AV_CH_LOW_FREQUENCY; |
|
|
|
st->codecpar->channels = av_get_channel_layout_nb_channels(st->codecpar->channel_layout); |
|
|
|
st->codecpar->bit_rate = data_rate*1000; |
|
} |
|
|
|
return 0; |
|
} |
|
|
|
/* |
|
* Remove start code emulation prevention 0x03 bytes |
|
*/ |
|
static void remove_scep_3_bytes(NALUnit *nalu) |
|
{ |
|
int i = 0; |
|
int j = 0; |
|
|
|
uint8_t *data = nalu->data; |
|
|
|
while (i < nalu->length) { |
|
if (nalu->length - i > 3 && AV_RB24(&data[i]) == 0x000003) { |
|
data[j++] = data[i++]; |
|
data[j++] = data[i++]; |
|
i++; |
|
} else { |
|
data[j++] = data[i++]; |
|
} |
|
} |
|
|
|
nalu->length = j; |
|
} |
|
|
|
static int get_next_nal_unit(CodecParserContext *ctx, NALUnit *nalu) |
|
{ |
|
const uint8_t *nalu_start = ctx->buf_ptr; |
|
|
|
if (ctx->buf_end - ctx->buf_ptr >= 4 && AV_RB32(ctx->buf_ptr) == 0x00000001) |
|
nalu->start_code_length = 4; |
|
else if (ctx->buf_end - ctx->buf_ptr >= 3 && AV_RB24(ctx->buf_ptr) == 0x000001) |
|
nalu->start_code_length = 3; |
|
else /* No start code at the beginning of the NAL unit */ |
|
return -1; |
|
|
|
ctx->buf_ptr += nalu->start_code_length; |
|
|
|
while (ctx->buf_ptr < ctx->buf_end) { |
|
if (ctx->buf_end - ctx->buf_ptr >= 4 && AV_RB32(ctx->buf_ptr) == 0x00000001) |
|
break; |
|
else if (ctx->buf_end - ctx->buf_ptr >= 3 && AV_RB24(ctx->buf_ptr) == 0x000001) |
|
break; |
|
ctx->buf_ptr++; |
|
} |
|
|
|
nalu->data = (uint8_t *)nalu_start + nalu->start_code_length; |
|
nalu->length = ctx->buf_ptr - nalu->data; |
|
nalu->type = *nalu->data & 0x1F; |
|
|
|
return 0; |
|
} |
|
|
|
static int decrypt_nal_unit(HLSCryptoContext *crypto_ctx, NALUnit *nalu) |
|
{ |
|
int ret = 0; |
|
int rem_bytes; |
|
uint8_t *data; |
|
uint8_t iv[16]; |
|
|
|
ret = av_aes_init(crypto_ctx->aes_ctx, crypto_ctx->key, 16 * 8, 1); |
|
if (ret < 0) |
|
return ret; |
|
|
|
/* Remove start code emulation prevention 0x03 bytes */ |
|
remove_scep_3_bytes(nalu); |
|
|
|
data = nalu->data + 32; |
|
rem_bytes = nalu->length - 32; |
|
|
|
memcpy(iv, crypto_ctx->iv, 16); |
|
|
|
while (rem_bytes > 0) { |
|
if (rem_bytes > 16) { |
|
av_aes_crypt(crypto_ctx->aes_ctx, data, data, 1, iv, 1); |
|
data += 16; |
|
rem_bytes -= 16; |
|
} |
|
data += FFMIN(144, rem_bytes); |
|
rem_bytes -= FFMIN(144, rem_bytes); |
|
} |
|
|
|
return 0; |
|
} |
|
|
|
static int decrypt_video_frame(HLSCryptoContext *crypto_ctx, AVPacket *pkt) |
|
{ |
|
int ret = 0; |
|
CodecParserContext ctx; |
|
NALUnit nalu; |
|
uint8_t *data_ptr; |
|
int move_nalu = 0; |
|
|
|
memset(&ctx, 0, sizeof(ctx)); |
|
ctx.buf_ptr = pkt->data; |
|
ctx.buf_end = pkt->data + pkt->size; |
|
|
|
data_ptr = pkt->data; |
|
|
|
while (ctx.buf_ptr < ctx.buf_end) { |
|
memset(&nalu, 0, sizeof(nalu)); |
|
ret = get_next_nal_unit(&ctx, &nalu); |
|
if (ret < 0) |
|
return ret; |
|
if ((nalu.type == 0x01 || nalu.type == 0x05) && nalu.length > 48) { |
|
int encrypted_nalu_length = nalu.length; |
|
ret = decrypt_nal_unit(crypto_ctx, &nalu); |
|
if (ret < 0) |
|
return ret; |
|
move_nalu = nalu.length != encrypted_nalu_length; |
|
} |
|
if (move_nalu) |
|
memmove(data_ptr, nalu.data - nalu.start_code_length, nalu.start_code_length + nalu.length); |
|
data_ptr += nalu.start_code_length + nalu.length; |
|
} |
|
|
|
av_shrink_packet(pkt, data_ptr - pkt->data); |
|
|
|
return 0; |
|
} |
|
|
|
static int get_next_adts_frame(CodecParserContext *ctx, AudioFrame *frame) |
|
{ |
|
int ret = 0; |
|
|
|
AACADTSHeaderInfo *adts_hdr = NULL; |
|
|
|
/* Find next sync word 0xFFF */ |
|
while (ctx->buf_ptr < ctx->buf_end - 1) { |
|
if (*ctx->buf_ptr == 0xFF && (*(ctx->buf_ptr + 1) & 0xF0) == 0xF0) |
|
break; |
|
ctx->buf_ptr++; |
|
} |
|
|
|
if (ctx->buf_ptr >= ctx->buf_end - 1) |
|
return -1; |
|
|
|
frame->data = (uint8_t*)ctx->buf_ptr; |
|
|
|
ret = avpriv_adts_header_parse (&adts_hdr, frame->data, ctx->buf_end - frame->data); |
|
if (ret < 0) |
|
return ret; |
|
|
|
frame->header_length = adts_hdr->crc_absent ? AV_AAC_ADTS_HEADER_SIZE : AV_AAC_ADTS_HEADER_SIZE + 2; |
|
frame->length = adts_hdr->frame_length; |
|
|
|
av_free(adts_hdr); |
|
|
|
return 0; |
|
} |
|
|
|
static int get_next_ac3_eac3_sync_frame(CodecParserContext *ctx, AudioFrame *frame) |
|
{ |
|
int ret = 0; |
|
|
|
AC3HeaderInfo *hdr = NULL; |
|
|
|
/* Find next sync word 0x0B77 */ |
|
while (ctx->buf_ptr < ctx->buf_end - 1) { |
|
if (*ctx->buf_ptr == 0x0B && *(ctx->buf_ptr + 1) == 0x77) |
|
break; |
|
ctx->buf_ptr++; |
|
} |
|
|
|
if (ctx->buf_ptr >= ctx->buf_end - 1) |
|
return -1; |
|
|
|
frame->data = (uint8_t*)ctx->buf_ptr; |
|
frame->header_length = 0; |
|
|
|
ret = avpriv_ac3_parse_header(&hdr, frame->data, ctx->buf_end - frame->data); |
|
if (ret < 0) { |
|
if (ret != AVERROR(ENOMEM)) |
|
av_free(hdr); |
|
return ret; |
|
} |
|
|
|
frame->length = hdr->frame_size; |
|
|
|
av_free(hdr); |
|
|
|
return 0; |
|
} |
|
|
|
static int get_next_sync_frame(enum AVCodecID codec_id, CodecParserContext *ctx, AudioFrame *frame) |
|
{ |
|
if (codec_id == AV_CODEC_ID_AAC) |
|
return get_next_adts_frame(ctx, frame); |
|
else if (codec_id == AV_CODEC_ID_AC3 || codec_id == AV_CODEC_ID_EAC3) |
|
return get_next_ac3_eac3_sync_frame(ctx, frame); |
|
else |
|
return AVERROR_INVALIDDATA; |
|
} |
|
|
|
static int decrypt_sync_frame(enum AVCodecID codec_id, HLSCryptoContext *crypto_ctx, AudioFrame *frame) |
|
{ |
|
int ret = 0; |
|
uint8_t *data; |
|
int num_of_encrypted_blocks; |
|
|
|
ret = av_aes_init(crypto_ctx->aes_ctx, crypto_ctx->key, 16 * 8, 1); |
|
if (ret < 0) |
|
return ret; |
|
|
|
data = frame->data + frame->header_length + 16; |
|
|
|
num_of_encrypted_blocks = (frame->length - frame->header_length - 16)/16; |
|
|
|
av_aes_crypt(crypto_ctx->aes_ctx, data, data, num_of_encrypted_blocks, crypto_ctx->iv, 1); |
|
|
|
return 0; |
|
} |
|
|
|
static int decrypt_audio_frame(enum AVCodecID codec_id, HLSCryptoContext *crypto_ctx, AVPacket *pkt) |
|
{ |
|
int ret = 0; |
|
CodecParserContext ctx; |
|
AudioFrame frame; |
|
|
|
memset(&ctx, 0, sizeof(ctx)); |
|
ctx.buf_ptr = pkt->data; |
|
ctx.buf_end = pkt->data + pkt->size; |
|
|
|
while (ctx.buf_ptr < ctx.buf_end) { |
|
memset(&frame, 0, sizeof(frame)); |
|
ret = get_next_sync_frame(codec_id, &ctx, &frame); |
|
if (ret < 0) |
|
return ret; |
|
if (frame.length - frame.header_length > 31) { |
|
ret = decrypt_sync_frame(codec_id, crypto_ctx, &frame); |
|
if (ret < 0) |
|
return ret; |
|
} |
|
ctx.buf_ptr += frame.length; |
|
} |
|
|
|
return 0; |
|
} |
|
|
|
int ff_hls_senc_decrypt_frame(enum AVCodecID codec_id, HLSCryptoContext *crypto_ctx, AVPacket *pkt) |
|
{ |
|
if (codec_id == AV_CODEC_ID_H264) |
|
return decrypt_video_frame(crypto_ctx, pkt); |
|
else if (codec_id == AV_CODEC_ID_AAC || codec_id == AV_CODEC_ID_AC3 || codec_id == AV_CODEC_ID_EAC3) |
|
return decrypt_audio_frame(codec_id, crypto_ctx, pkt); |
|
|
|
return AVERROR_INVALIDDATA; |
|
}
|
|
|