FFmpeg coverage

Directory: ../../../ffmpeg/
File: src/libavformat/hls_sample_encryption.c
Date: 2025-10-26 07:25:09
Exec Total Coverage
Lines: 0 197 0.0%
Functions: 0 12 0.0%
Branches: 0 118 0.0%
Line Branch Exec Source
1 /*
2 * Apple HTTP Live Streaming Sample Encryption/Decryption
3 *
4 * Copyright (c) 2021 Nachiket Tarate
5 *
6 * This file is part of FFmpeg.
7 *
8 * FFmpeg is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU Lesser General Public
10 * License as published by the Free Software Foundation; either
11 * version 2.1 of the License, or (at your option) any later version.
12 *
13 * FFmpeg is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 * Lesser General Public License for more details.
17 *
18 * You should have received a copy of the GNU Lesser General Public
19 * License along with FFmpeg; if not, write to the Free Software
20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21 */
22
23 /**
24 * @file
25 * Apple HTTP Live Streaming Sample Encryption
26 * https://developer.apple.com/library/ios/documentation/AudioVideo/Conceptual/HLS_Sample_Encryption
27 */
28
29 #include "libavutil/aes.h"
30 #include "libavutil/channel_layout.h"
31 #include "libavutil/mem.h"
32
33 #include "hls_sample_encryption.h"
34
35 #include "libavcodec/adts_header.h"
36 #include "libavcodec/adts_parser.h"
37 #include "libavcodec/ac3tab.h"
38 #include "libavcodec/ac3_parser_internal.h"
39
40
41 typedef struct NALUnit {
42 uint8_t *data;
43 int type;
44 int length;
45 int start_code_length;
46 } NALUnit;
47
48 typedef struct AudioFrame {
49 uint8_t *data;
50 int length;
51 int header_length;
52 } AudioFrame;
53
54 typedef struct CodecParserContext {
55 const uint8_t *buf_ptr;
56 const uint8_t *buf_end;
57 } CodecParserContext;
58
59 static const int eac3_sample_rate_tab[] = { 48000, 44100, 32000, 0 };
60
61 ✗ void ff_hls_senc_read_audio_setup_info(HLSAudioSetupInfo *info, const uint8_t *buf, size_t size)
62 {
63 ✗ if (size < 8)
64 ✗ return;
65
66 ✗ info->codec_tag = AV_RL32(buf);
67
68 /* Always keep this list in sync with the one from hls_read_header() */
69 ✗ if (info->codec_tag == MKTAG('z','a','a','c'))
70 ✗ info->codec_id = AV_CODEC_ID_AAC;
71 ✗ else if (info->codec_tag == MKTAG('z','a','c','3'))
72 ✗ info->codec_id = AV_CODEC_ID_AC3;
73 ✗ else if (info->codec_tag == MKTAG('z','e','c','3'))
74 ✗ info->codec_id = AV_CODEC_ID_EAC3;
75 else
76 ✗ info->codec_id = AV_CODEC_ID_NONE;
77
78 ✗ buf += 4;
79 ✗ info->priming = AV_RL16(buf);
80 ✗ buf += 2;
81 ✗ info->version = *buf++;
82 ✗ info->setup_data_length = *buf++;
83
84 ✗ if (info->setup_data_length > size - 8)
85 ✗ info->setup_data_length = size - 8;
86
87 ✗ if (info->setup_data_length > HLS_MAX_AUDIO_SETUP_DATA_LEN)
88 ✗ return;
89
90 ✗ memcpy(info->setup_data, buf, info->setup_data_length);
91 }
92
93 ✗ int ff_hls_senc_parse_audio_setup_info(AVStream *st, HLSAudioSetupInfo *info)
94 {
95 ✗ int ret = 0;
96
97 ✗ st->codecpar->codec_tag = info->codec_tag;
98
99 ✗ if (st->codecpar->codec_id == AV_CODEC_ID_AAC)
100 ✗ return 0;
101
102 ✗ if (st->codecpar->codec_id != AV_CODEC_ID_AC3 && st->codecpar->codec_id != AV_CODEC_ID_EAC3)
103 ✗ return AVERROR_INVALIDDATA;
104
105 ✗ if (st->codecpar->codec_id == AV_CODEC_ID_AC3) {
106 ✗ AC3HeaderInfo *ac3hdr = NULL;
107
108 ✗ ret = avpriv_ac3_parse_header(&ac3hdr, info->setup_data, info->setup_data_length);
109 ✗ if (ret < 0) {
110 ✗ av_free(ac3hdr);
111 ✗ return ret;
112 }
113
114 ✗ st->codecpar->sample_rate = ac3hdr->sample_rate;
115 ✗ av_channel_layout_uninit(&st->codecpar->ch_layout);
116 ✗ av_channel_layout_from_mask(&st->codecpar->ch_layout, ac3hdr->channel_layout);
117 ✗ st->codecpar->bit_rate = ac3hdr->bit_rate;
118
119 ✗ av_free(ac3hdr);
120 } else { /* Parse 'dec3' EC3SpecificBox */
121 GetBitContext gb;
122 uint64_t mask;
123 int data_rate, fscod, acmod, lfeon;
124
125 ✗ ret = init_get_bits8(&gb, info->setup_data, info->setup_data_length);
126 ✗ if (ret < 0)
127 ✗ return AVERROR_INVALIDDATA;
128
129 ✗ data_rate = get_bits(&gb, 13);
130 ✗ skip_bits(&gb, 3);
131 ✗ fscod = get_bits(&gb, 2);
132 ✗ skip_bits(&gb, 10);
133 ✗ acmod = get_bits(&gb, 3);
134 ✗ lfeon = get_bits(&gb, 1);
135
136 ✗ st->codecpar->sample_rate = eac3_sample_rate_tab[fscod];
137
138 ✗ mask = ff_ac3_channel_layout_tab[acmod];
139 ✗ if (lfeon)
140 ✗ mask |= AV_CH_LOW_FREQUENCY;
141
142 ✗ av_channel_layout_uninit(&st->codecpar->ch_layout);
143 ✗ av_channel_layout_from_mask(&st->codecpar->ch_layout, mask);
144
145 ✗ st->codecpar->bit_rate = data_rate*1000;
146 }
147
148 ✗ return 0;
149 }
150
151 /*
152 * Remove start code emulation prevention 0x03 bytes
153 */
154 ✗ static void remove_scep_3_bytes(NALUnit *nalu)
155 {
156 ✗ int i = 0;
157 ✗ int j = 0;
158
159 ✗ uint8_t *data = nalu->data;
160
161 ✗ while (i < nalu->length) {
162 ✗ if (nalu->length - i > 3 && AV_RB24(&data[i]) == 0x000003) {
163 ✗ data[j++] = data[i++];
164 ✗ data[j++] = data[i++];
165 ✗ i++;
166 } else {
167 ✗ data[j++] = data[i++];
168 }
169 }
170
171 ✗ nalu->length = j;
172 ✗ }
173
174 ✗ static int get_next_nal_unit(CodecParserContext *ctx, NALUnit *nalu)
175 {
176 ✗ const uint8_t *nalu_start = ctx->buf_ptr;
177
178 ✗ if (ctx->buf_end - ctx->buf_ptr >= 4 && AV_RB32(ctx->buf_ptr) == 0x00000001)
179 ✗ nalu->start_code_length = 4;
180 ✗ else if (ctx->buf_end - ctx->buf_ptr >= 3 && AV_RB24(ctx->buf_ptr) == 0x000001)
181 ✗ nalu->start_code_length = 3;
182 else /* No start code at the beginning of the NAL unit */
183 ✗ return -1;
184
185 ✗ ctx->buf_ptr += nalu->start_code_length;
186
187 ✗ while (ctx->buf_ptr < ctx->buf_end) {
188 ✗ if (ctx->buf_end - ctx->buf_ptr >= 4 && AV_RB32(ctx->buf_ptr) == 0x00000001)
189 break;
190 ✗ else if (ctx->buf_end - ctx->buf_ptr >= 3 && AV_RB24(ctx->buf_ptr) == 0x000001)
191 ✗ break;
192 ✗ ctx->buf_ptr++;
193 }
194
195 ✗ nalu->data = (uint8_t *)nalu_start + nalu->start_code_length;
196 ✗ nalu->length = ctx->buf_ptr - nalu->data;
197 ✗ nalu->type = *nalu->data & 0x1F;
198
199 ✗ return 0;
200 }
201
202 ✗ static int decrypt_nal_unit(HLSCryptoContext *crypto_ctx, NALUnit *nalu)
203 {
204 ✗ int ret = 0;
205 int rem_bytes;
206 uint8_t *data;
207 uint8_t iv[16];
208
209 ✗ ret = av_aes_init(crypto_ctx->aes_ctx, crypto_ctx->key, 16 * 8, 1);
210 ✗ if (ret < 0)
211 ✗ return ret;
212
213 /* Remove start code emulation prevention 0x03 bytes */
214 ✗ remove_scep_3_bytes(nalu);
215
216 ✗ data = nalu->data + 32;
217 ✗ rem_bytes = nalu->length - 32;
218
219 ✗ memcpy(iv, crypto_ctx->iv, 16);
220
221 ✗ while (rem_bytes > 0) {
222 ✗ if (rem_bytes > 16) {
223 ✗ av_aes_crypt(crypto_ctx->aes_ctx, data, data, 1, iv, 1);
224 ✗ data += 16;
225 ✗ rem_bytes -= 16;
226 }
227 ✗ data += FFMIN(144, rem_bytes);
228 ✗ rem_bytes -= FFMIN(144, rem_bytes);
229 }
230
231 ✗ return 0;
232 }
233
234 ✗ static int decrypt_video_frame(HLSCryptoContext *crypto_ctx, AVPacket *pkt)
235 {
236 ✗ int ret = 0;
237 CodecParserContext ctx;
238 NALUnit nalu;
239 uint8_t *data_ptr;
240 ✗ int move_nalu = 0;
241
242 ✗ memset(&ctx, 0, sizeof(ctx));
243 ✗ ctx.buf_ptr = pkt->data;
244 ✗ ctx.buf_end = pkt->data + pkt->size;
245
246 ✗ data_ptr = pkt->data;
247
248 ✗ while (ctx.buf_ptr < ctx.buf_end) {
249 ✗ memset(&nalu, 0, sizeof(nalu));
250 ✗ ret = get_next_nal_unit(&ctx, &nalu);
251 ✗ if (ret < 0)
252 ✗ return ret;
253 ✗ if ((nalu.type == 0x01 || nalu.type == 0x05) && nalu.length > 48) {
254 ✗ int encrypted_nalu_length = nalu.length;
255 ✗ ret = decrypt_nal_unit(crypto_ctx, &nalu);
256 ✗ if (ret < 0)
257 ✗ return ret;
258 ✗ move_nalu = nalu.length != encrypted_nalu_length;
259 }
260 ✗ if (move_nalu)
261 ✗ memmove(data_ptr, nalu.data - nalu.start_code_length, nalu.start_code_length + nalu.length);
262 ✗ data_ptr += nalu.start_code_length + nalu.length;
263 }
264
265 ✗ av_shrink_packet(pkt, data_ptr - pkt->data);
266
267 ✗ return 0;
268 }
269
270 ✗ static int get_next_adts_frame(CodecParserContext *ctx, AudioFrame *frame)
271 {
272 ✗ int ret = 0;
273
274 ✗ AACADTSHeaderInfo *adts_hdr = NULL;
275
276 /* Find next sync word 0xFFF */
277 ✗ while (ctx->buf_ptr < ctx->buf_end - 1) {
278 ✗ if (*ctx->buf_ptr == 0xFF && (*(ctx->buf_ptr + 1) & 0xF0) == 0xF0)
279 ✗ break;
280 ✗ ctx->buf_ptr++;
281 }
282
283 ✗ if (ctx->buf_ptr >= ctx->buf_end - 1)
284 ✗ return -1;
285
286 ✗ frame->data = (uint8_t*)ctx->buf_ptr;
287
288 ✗ ret = avpriv_adts_header_parse (&adts_hdr, frame->data, ctx->buf_end - frame->data);
289 ✗ if (ret < 0)
290 ✗ return ret;
291
292 ✗ frame->header_length = adts_hdr->crc_absent ? AV_AAC_ADTS_HEADER_SIZE : AV_AAC_ADTS_HEADER_SIZE + 2;
293 ✗ frame->length = adts_hdr->frame_length;
294
295 ✗ av_free(adts_hdr);
296
297 ✗ return 0;
298 }
299
300 ✗ static int get_next_ac3_eac3_sync_frame(CodecParserContext *ctx, AudioFrame *frame)
301 {
302 ✗ int ret = 0;
303
304 ✗ AC3HeaderInfo *hdr = NULL;
305
306 /* Find next sync word 0x0B77 */
307 ✗ while (ctx->buf_ptr < ctx->buf_end - 1) {
308 ✗ if (*ctx->buf_ptr == 0x0B && *(ctx->buf_ptr + 1) == 0x77)
309 ✗ break;
310 ✗ ctx->buf_ptr++;
311 }
312
313 ✗ if (ctx->buf_ptr >= ctx->buf_end - 1)
314 ✗ return -1;
315
316 ✗ frame->data = (uint8_t*)ctx->buf_ptr;
317 ✗ frame->header_length = 0;
318
319 ✗ ret = avpriv_ac3_parse_header(&hdr, frame->data, ctx->buf_end - frame->data);
320 ✗ if (ret < 0) {
321 ✗ av_free(hdr);
322 ✗ return ret;
323 }
324
325 ✗ frame->length = hdr->frame_size;
326
327 ✗ av_free(hdr);
328
329 ✗ return 0;
330 }
331
332 ✗ static int get_next_sync_frame(enum AVCodecID codec_id, CodecParserContext *ctx, AudioFrame *frame)
333 {
334 ✗ if (codec_id == AV_CODEC_ID_AAC)
335 ✗ return get_next_adts_frame(ctx, frame);
336 ✗ else if (codec_id == AV_CODEC_ID_AC3 || codec_id == AV_CODEC_ID_EAC3)
337 ✗ return get_next_ac3_eac3_sync_frame(ctx, frame);
338 else
339 ✗ return AVERROR_INVALIDDATA;
340 }
341
342 ✗ static int decrypt_sync_frame(enum AVCodecID codec_id, HLSCryptoContext *crypto_ctx, AudioFrame *frame)
343 {
344 ✗ int ret = 0;
345 uint8_t *data;
346 int num_of_encrypted_blocks;
347
348 ✗ ret = av_aes_init(crypto_ctx->aes_ctx, crypto_ctx->key, 16 * 8, 1);
349 ✗ if (ret < 0)
350 ✗ return ret;
351
352 ✗ data = frame->data + frame->header_length + 16;
353
354 ✗ num_of_encrypted_blocks = (frame->length - frame->header_length - 16)/16;
355
356 ✗ av_aes_crypt(crypto_ctx->aes_ctx, data, data, num_of_encrypted_blocks, crypto_ctx->iv, 1);
357
358 ✗ return 0;
359 }
360
361 ✗ static int decrypt_audio_frame(enum AVCodecID codec_id, HLSCryptoContext *crypto_ctx, AVPacket *pkt)
362 {
363 ✗ int ret = 0;
364 CodecParserContext ctx;
365 AudioFrame frame;
366
367 ✗ memset(&ctx, 0, sizeof(ctx));
368 ✗ ctx.buf_ptr = pkt->data;
369 ✗ ctx.buf_end = pkt->data + pkt->size;
370
371 ✗ while (ctx.buf_ptr < ctx.buf_end) {
372 ✗ memset(&frame, 0, sizeof(frame));
373 ✗ ret = get_next_sync_frame(codec_id, &ctx, &frame);
374 ✗ if (ret < 0)
375 ✗ return ret;
376 ✗ if (frame.length - frame.header_length > 31) {
377 ✗ ret = decrypt_sync_frame(codec_id, crypto_ctx, &frame);
378 ✗ if (ret < 0)
379 ✗ return ret;
380 }
381 ✗ ctx.buf_ptr += frame.length;
382 }
383
384 ✗ return 0;
385 }
386
387 ✗ int ff_hls_senc_decrypt_frame(enum AVCodecID codec_id, HLSCryptoContext *crypto_ctx, AVPacket *pkt)
388 {
389 ✗ if (codec_id == AV_CODEC_ID_H264)
390 ✗ return decrypt_video_frame(crypto_ctx, pkt);
391 ✗ else if (codec_id == AV_CODEC_ID_AAC || codec_id == AV_CODEC_ID_AC3 || codec_id == AV_CODEC_ID_EAC3)
392 ✗ return decrypt_audio_frame(codec_id, crypto_ctx, pkt);
393
394 ✗ return AVERROR_INVALIDDATA;
395 }
396