crypto: Don't manually free memory allocated via AVOptions
[libav.git] / libavformat / crypto.c
1 /*
2 * Decryption protocol handler
3 * Copyright (c) 2011 Martin Storsjo
4 *
5 * This file is part of Libav.
6 *
7 * Libav is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
11 *
12 * Libav is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
16 *
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with Libav; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20 */
21
22 #include "avformat.h"
23 #include "libavutil/aes.h"
24 #include "libavutil/avstring.h"
25 #include "libavutil/opt.h"
26 #include "internal.h"
27 #include "url.h"
28
29 #define MAX_BUFFER_BLOCKS 150
30 #define BLOCKSIZE 16
31
32 typedef struct {
33 const AVClass *class;
34 URLContext *hd;
35 uint8_t inbuffer [BLOCKSIZE*MAX_BUFFER_BLOCKS],
36 outbuffer[BLOCKSIZE*MAX_BUFFER_BLOCKS];
37 uint8_t *outptr;
38 int indata, indata_used, outdata;
39 int eof;
40 uint8_t *key;
41 int keylen;
42 uint8_t *iv;
43 int ivlen;
44 struct AVAES *aes;
45 } CryptoContext;
46
47 #define OFFSET(x) offsetof(CryptoContext, x)
48 static const AVOption options[] = {
49 {"key", "AES decryption key", OFFSET(key), AV_OPT_TYPE_BINARY },
50 {"iv", "AES decryption initialization vector", OFFSET(iv), AV_OPT_TYPE_BINARY },
51 { NULL }
52 };
53
54 static const AVClass crypto_class = {
55 .class_name = "crypto",
56 .item_name = av_default_item_name,
57 .option = options,
58 .version = LIBAVUTIL_VERSION_INT,
59 };
60
61 static int crypto_open(URLContext *h, const char *uri, int flags)
62 {
63 const char *nested_url;
64 int ret = 0;
65 CryptoContext *c = h->priv_data;
66
67 if (!av_strstart(uri, "crypto+", &nested_url) &&
68 !av_strstart(uri, "crypto:", &nested_url)) {
69 av_log(h, AV_LOG_ERROR, "Unsupported url %s\n", uri);
70 ret = AVERROR(EINVAL);
71 goto err;
72 }
73
74 if (c->keylen < BLOCKSIZE || c->ivlen < BLOCKSIZE) {
75 av_log(h, AV_LOG_ERROR, "Key or IV not set\n");
76 ret = AVERROR(EINVAL);
77 goto err;
78 }
79 if (flags & AVIO_FLAG_WRITE) {
80 av_log(h, AV_LOG_ERROR, "Only decryption is supported currently\n");
81 ret = AVERROR(ENOSYS);
82 goto err;
83 }
84 if ((ret = ffurl_open(&c->hd, nested_url, AVIO_FLAG_READ)) < 0) {
85 av_log(h, AV_LOG_ERROR, "Unable to open input\n");
86 goto err;
87 }
88 c->aes = av_mallocz(av_aes_size);
89 if (!c->aes) {
90 ret = AVERROR(ENOMEM);
91 goto err;
92 }
93
94 av_aes_init(c->aes, c->key, 128, 1);
95
96 h->is_streamed = 1;
97
98 err:
99 return ret;
100 }
101
102 static int crypto_read(URLContext *h, uint8_t *buf, int size)
103 {
104 CryptoContext *c = h->priv_data;
105 int blocks;
106 retry:
107 if (c->outdata > 0) {
108 size = FFMIN(size, c->outdata);
109 memcpy(buf, c->outptr, size);
110 c->outptr += size;
111 c->outdata -= size;
112 return size;
113 }
114 // We avoid using the last block until we've found EOF,
115 // since we'll remove PKCS7 padding at the end. So make
116 // sure we've got at least 2 blocks, so we can decrypt
117 // at least one.
118 while (c->indata - c->indata_used < 2*BLOCKSIZE) {
119 int n = ffurl_read(c->hd, c->inbuffer + c->indata,
120 sizeof(c->inbuffer) - c->indata);
121 if (n <= 0) {
122 c->eof = 1;
123 break;
124 }
125 c->indata += n;
126 }
127 blocks = (c->indata - c->indata_used) / BLOCKSIZE;
128 if (!blocks)
129 return AVERROR_EOF;
130 if (!c->eof)
131 blocks--;
132 av_aes_crypt(c->aes, c->outbuffer, c->inbuffer + c->indata_used, blocks,
133 c->iv, 1);
134 c->outdata = BLOCKSIZE * blocks;
135 c->outptr = c->outbuffer;
136 c->indata_used += BLOCKSIZE * blocks;
137 if (c->indata_used >= sizeof(c->inbuffer)/2) {
138 memmove(c->inbuffer, c->inbuffer + c->indata_used,
139 c->indata - c->indata_used);
140 c->indata -= c->indata_used;
141 c->indata_used = 0;
142 }
143 if (c->eof) {
144 // Remove PKCS7 padding at the end
145 int padding = c->outbuffer[c->outdata - 1];
146 c->outdata -= padding;
147 }
148 goto retry;
149 }
150
151 static int crypto_close(URLContext *h)
152 {
153 CryptoContext *c = h->priv_data;
154 if (c->hd)
155 ffurl_close(c->hd);
156 av_freep(&c->aes);
157 return 0;
158 }
159
160 URLProtocol ff_crypto_protocol = {
161 .name = "crypto",
162 .url_open = crypto_open,
163 .url_read = crypto_read,
164 .url_close = crypto_close,
165 .priv_data_size = sizeof(CryptoContext),
166 .priv_data_class = &crypto_class,
167 .flags = URL_PROTOCOL_FLAG_NESTED_SCHEME,
168 };