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.
170 lines
4.9 KiB
170 lines
4.9 KiB
/* |
|
* Decryption protocol handler |
|
* Copyright (c) 2011 Martin Storsjo |
|
* |
|
* 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 |
|
*/ |
|
|
|
#include "avformat.h" |
|
#include "libavutil/aes.h" |
|
#include "libavutil/avstring.h" |
|
#include "libavutil/opt.h" |
|
#include "internal.h" |
|
#include "url.h" |
|
|
|
#define MAX_BUFFER_BLOCKS 150 |
|
#define BLOCKSIZE 16 |
|
|
|
typedef struct { |
|
const AVClass *class; |
|
URLContext *hd; |
|
uint8_t inbuffer [BLOCKSIZE*MAX_BUFFER_BLOCKS], |
|
outbuffer[BLOCKSIZE*MAX_BUFFER_BLOCKS]; |
|
uint8_t *outptr; |
|
int indata, indata_used, outdata; |
|
int eof; |
|
uint8_t *key; |
|
int keylen; |
|
uint8_t *iv; |
|
int ivlen; |
|
struct AVAES *aes; |
|
} CryptoContext; |
|
|
|
#define OFFSET(x) offsetof(CryptoContext, x) |
|
#define D AV_OPT_FLAG_DECODING_PARAM |
|
static const AVOption options[] = { |
|
{"key", "AES decryption key", OFFSET(key), AV_OPT_TYPE_BINARY, .flags = D }, |
|
{"iv", "AES decryption initialization vector", OFFSET(iv), AV_OPT_TYPE_BINARY, .flags = D }, |
|
{ NULL } |
|
}; |
|
|
|
static const AVClass crypto_class = { |
|
.class_name = "crypto", |
|
.item_name = av_default_item_name, |
|
.option = options, |
|
.version = LIBAVUTIL_VERSION_INT, |
|
}; |
|
|
|
static int crypto_open2(URLContext *h, const char *uri, int flags, AVDictionary **options) |
|
{ |
|
const char *nested_url; |
|
int ret = 0; |
|
CryptoContext *c = h->priv_data; |
|
|
|
if (!av_strstart(uri, "crypto+", &nested_url) && |
|
!av_strstart(uri, "crypto:", &nested_url)) { |
|
av_log(h, AV_LOG_ERROR, "Unsupported url %s\n", uri); |
|
ret = AVERROR(EINVAL); |
|
goto err; |
|
} |
|
|
|
if (c->keylen < BLOCKSIZE || c->ivlen < BLOCKSIZE) { |
|
av_log(h, AV_LOG_ERROR, "Key or IV not set\n"); |
|
ret = AVERROR(EINVAL); |
|
goto err; |
|
} |
|
if (flags & AVIO_FLAG_WRITE) { |
|
av_log(h, AV_LOG_ERROR, "Only decryption is supported currently\n"); |
|
ret = AVERROR(ENOSYS); |
|
goto err; |
|
} |
|
if ((ret = ffurl_open(&c->hd, nested_url, AVIO_FLAG_READ, |
|
&h->interrupt_callback, options)) < 0) { |
|
av_log(h, AV_LOG_ERROR, "Unable to open input\n"); |
|
goto err; |
|
} |
|
c->aes = av_mallocz(av_aes_size); |
|
if (!c->aes) { |
|
ret = AVERROR(ENOMEM); |
|
goto err; |
|
} |
|
|
|
av_aes_init(c->aes, c->key, 128, 1); |
|
|
|
h->is_streamed = 1; |
|
|
|
err: |
|
return ret; |
|
} |
|
|
|
static int crypto_read(URLContext *h, uint8_t *buf, int size) |
|
{ |
|
CryptoContext *c = h->priv_data; |
|
int blocks; |
|
retry: |
|
if (c->outdata > 0) { |
|
size = FFMIN(size, c->outdata); |
|
memcpy(buf, c->outptr, size); |
|
c->outptr += size; |
|
c->outdata -= size; |
|
return size; |
|
} |
|
// We avoid using the last block until we've found EOF, |
|
// since we'll remove PKCS7 padding at the end. So make |
|
// sure we've got at least 2 blocks, so we can decrypt |
|
// at least one. |
|
while (c->indata - c->indata_used < 2*BLOCKSIZE) { |
|
int n = ffurl_read(c->hd, c->inbuffer + c->indata, |
|
sizeof(c->inbuffer) - c->indata); |
|
if (n <= 0) { |
|
c->eof = 1; |
|
break; |
|
} |
|
c->indata += n; |
|
} |
|
blocks = (c->indata - c->indata_used) / BLOCKSIZE; |
|
if (!blocks) |
|
return AVERROR_EOF; |
|
if (!c->eof) |
|
blocks--; |
|
av_aes_crypt(c->aes, c->outbuffer, c->inbuffer + c->indata_used, blocks, |
|
c->iv, 1); |
|
c->outdata = BLOCKSIZE * blocks; |
|
c->outptr = c->outbuffer; |
|
c->indata_used += BLOCKSIZE * blocks; |
|
if (c->indata_used >= sizeof(c->inbuffer)/2) { |
|
memmove(c->inbuffer, c->inbuffer + c->indata_used, |
|
c->indata - c->indata_used); |
|
c->indata -= c->indata_used; |
|
c->indata_used = 0; |
|
} |
|
if (c->eof) { |
|
// Remove PKCS7 padding at the end |
|
int padding = c->outbuffer[c->outdata - 1]; |
|
c->outdata -= padding; |
|
} |
|
goto retry; |
|
} |
|
|
|
static int crypto_close(URLContext *h) |
|
{ |
|
CryptoContext *c = h->priv_data; |
|
if (c->hd) |
|
ffurl_close(c->hd); |
|
av_freep(&c->aes); |
|
return 0; |
|
} |
|
|
|
URLProtocol ff_crypto_protocol = { |
|
.name = "crypto", |
|
.url_open2 = crypto_open2, |
|
.url_read = crypto_read, |
|
.url_close = crypto_close, |
|
.priv_data_size = sizeof(CryptoContext), |
|
.priv_data_class = &crypto_class, |
|
.flags = URL_PROTOCOL_FLAG_NESTED_SCHEME, |
|
};
|
|
|