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2ba45a60 DM |
1 | /* |
2 | * Decryption protocol handler | |
3 | * Copyright (c) 2011 Martin Storsjo | |
4 | * | |
5 | * This file is part of FFmpeg. | |
6 | * | |
7 | * FFmpeg 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 | * FFmpeg 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 FFmpeg; 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; | |
f6fa7814 DM |
44 | uint8_t *decrypt_key; |
45 | int decrypt_keylen; | |
46 | uint8_t *decrypt_iv; | |
47 | int decrypt_ivlen; | |
48 | uint8_t *encrypt_key; | |
49 | int encrypt_keylen; | |
50 | uint8_t *encrypt_iv; | |
51 | int encrypt_ivlen; | |
52 | struct AVAES *aes_decrypt; | |
53 | struct AVAES *aes_encrypt; | |
54 | ||
55 | uint8_t pad[BLOCKSIZE]; | |
56 | int pad_len; | |
57 | ||
2ba45a60 DM |
58 | } CryptoContext; |
59 | ||
60 | #define OFFSET(x) offsetof(CryptoContext, x) | |
61 | #define D AV_OPT_FLAG_DECODING_PARAM | |
f6fa7814 | 62 | #define E AV_OPT_FLAG_ENCODING_PARAM |
2ba45a60 | 63 | static const AVOption options[] = { |
f6fa7814 DM |
64 | {"key", "AES encryption/decryption key", OFFSET(key), AV_OPT_TYPE_BINARY, .flags = D|E }, |
65 | {"iv", "AES encryption/decryption initialization vector", OFFSET(iv), AV_OPT_TYPE_BINARY, .flags = D|E }, | |
66 | {"decryption_key", "AES decryption key", OFFSET(decrypt_key), AV_OPT_TYPE_BINARY, .flags = D }, | |
67 | {"decryption_iv", "AES decryption initialization vector", OFFSET(decrypt_iv), AV_OPT_TYPE_BINARY, .flags = D }, | |
68 | {"encryption_key", "AES encryption key", OFFSET(encrypt_key), AV_OPT_TYPE_BINARY, .flags = E }, | |
69 | {"encryption_iv", "AES encryption initialization vector", OFFSET(encrypt_iv), AV_OPT_TYPE_BINARY, .flags = E }, | |
2ba45a60 DM |
70 | { NULL } |
71 | }; | |
72 | ||
73 | static const AVClass crypto_class = { | |
74 | .class_name = "crypto", | |
75 | .item_name = av_default_item_name, | |
76 | .option = options, | |
77 | .version = LIBAVUTIL_VERSION_INT, | |
78 | }; | |
79 | ||
f6fa7814 DM |
80 | static int set_aes_arg(CryptoContext *c, uint8_t **buf, int *buf_len, |
81 | uint8_t *default_buf, int default_buf_len, | |
82 | const char *desc) | |
83 | { | |
84 | if (!*buf_len) { | |
85 | if (!default_buf_len) { | |
86 | av_log(c, AV_LOG_ERROR, "%s not set\n", desc); | |
87 | return AVERROR(EINVAL); | |
88 | } else if (default_buf_len != BLOCKSIZE) { | |
89 | av_log(c, AV_LOG_ERROR, | |
90 | "invalid %s size (%d bytes, block size is %d)\n", | |
91 | desc, default_buf_len, BLOCKSIZE); | |
92 | return AVERROR(EINVAL); | |
93 | } | |
94 | *buf = av_memdup(default_buf, default_buf_len); | |
95 | if (!*buf) | |
96 | return AVERROR(ENOMEM); | |
97 | *buf_len = default_buf_len; | |
98 | } else if (*buf_len != BLOCKSIZE) { | |
99 | av_log(c, AV_LOG_ERROR, | |
100 | "invalid %s size (%d bytes, block size is %d)\n", | |
101 | desc, *buf_len, BLOCKSIZE); | |
102 | return AVERROR(EINVAL); | |
103 | } | |
104 | return 0; | |
105 | } | |
106 | ||
2ba45a60 DM |
107 | static int crypto_open2(URLContext *h, const char *uri, int flags, AVDictionary **options) |
108 | { | |
109 | const char *nested_url; | |
110 | int ret = 0; | |
111 | CryptoContext *c = h->priv_data; | |
112 | ||
113 | if (!av_strstart(uri, "crypto+", &nested_url) && | |
114 | !av_strstart(uri, "crypto:", &nested_url)) { | |
115 | av_log(h, AV_LOG_ERROR, "Unsupported url %s\n", uri); | |
116 | ret = AVERROR(EINVAL); | |
117 | goto err; | |
118 | } | |
119 | ||
f6fa7814 DM |
120 | if (flags & AVIO_FLAG_READ) { |
121 | if ((ret = set_aes_arg(c, &c->decrypt_key, &c->decrypt_keylen, | |
122 | c->key, c->keylen, "decryption key")) < 0) | |
123 | goto err; | |
124 | if ((ret = set_aes_arg(c, &c->decrypt_iv, &c->decrypt_ivlen, | |
dcebb6f3 | 125 | c->iv, c->ivlen, "decryption IV")) < 0) |
f6fa7814 | 126 | goto err; |
2ba45a60 | 127 | } |
f6fa7814 | 128 | |
2ba45a60 | 129 | if (flags & AVIO_FLAG_WRITE) { |
f6fa7814 DM |
130 | if ((ret = set_aes_arg(c, &c->encrypt_key, &c->encrypt_keylen, |
131 | c->key, c->keylen, "encryption key")) < 0) | |
132 | if (ret < 0) | |
133 | goto err; | |
134 | if ((ret = set_aes_arg(c, &c->encrypt_iv, &c->encrypt_ivlen, | |
dcebb6f3 | 135 | c->iv, c->ivlen, "encryption IV")) < 0) |
f6fa7814 | 136 | goto err; |
2ba45a60 | 137 | } |
f6fa7814 DM |
138 | |
139 | if ((ret = ffurl_open(&c->hd, nested_url, flags, | |
2ba45a60 | 140 | &h->interrupt_callback, options)) < 0) { |
f6fa7814 | 141 | av_log(h, AV_LOG_ERROR, "Unable to open resource: %s\n", nested_url); |
2ba45a60 DM |
142 | goto err; |
143 | } | |
f6fa7814 DM |
144 | |
145 | if (flags & AVIO_FLAG_READ) { | |
146 | c->aes_decrypt = av_aes_alloc(); | |
147 | if (!c->aes_decrypt) { | |
148 | ret = AVERROR(ENOMEM); | |
149 | goto err; | |
150 | } | |
151 | ret = av_aes_init(c->aes_decrypt, c->decrypt_key, BLOCKSIZE*8, 1); | |
152 | if (ret < 0) | |
153 | goto err; | |
2ba45a60 DM |
154 | } |
155 | ||
f6fa7814 DM |
156 | if (flags & AVIO_FLAG_WRITE) { |
157 | c->aes_encrypt = av_aes_alloc(); | |
158 | if (!c->aes_encrypt) { | |
159 | ret = AVERROR(ENOMEM); | |
160 | goto err; | |
161 | } | |
162 | ret = av_aes_init(c->aes_encrypt, c->encrypt_key, BLOCKSIZE*8, 0); | |
163 | if (ret < 0) | |
164 | goto err; | |
165 | } | |
166 | ||
167 | c->pad_len = 0; | |
2ba45a60 DM |
168 | |
169 | h->is_streamed = 1; | |
170 | ||
171 | err: | |
172 | return ret; | |
173 | } | |
174 | ||
175 | static int crypto_read(URLContext *h, uint8_t *buf, int size) | |
176 | { | |
177 | CryptoContext *c = h->priv_data; | |
178 | int blocks; | |
179 | retry: | |
180 | if (c->outdata > 0) { | |
181 | size = FFMIN(size, c->outdata); | |
182 | memcpy(buf, c->outptr, size); | |
183 | c->outptr += size; | |
184 | c->outdata -= size; | |
185 | return size; | |
186 | } | |
187 | // We avoid using the last block until we've found EOF, | |
188 | // since we'll remove PKCS7 padding at the end. So make | |
189 | // sure we've got at least 2 blocks, so we can decrypt | |
190 | // at least one. | |
191 | while (c->indata - c->indata_used < 2*BLOCKSIZE) { | |
192 | int n = ffurl_read(c->hd, c->inbuffer + c->indata, | |
193 | sizeof(c->inbuffer) - c->indata); | |
194 | if (n <= 0) { | |
195 | c->eof = 1; | |
196 | break; | |
197 | } | |
198 | c->indata += n; | |
199 | } | |
200 | blocks = (c->indata - c->indata_used) / BLOCKSIZE; | |
201 | if (!blocks) | |
202 | return AVERROR_EOF; | |
203 | if (!c->eof) | |
204 | blocks--; | |
f6fa7814 DM |
205 | av_aes_crypt(c->aes_decrypt, c->outbuffer, c->inbuffer + c->indata_used, |
206 | blocks, c->decrypt_iv, 1); | |
2ba45a60 DM |
207 | c->outdata = BLOCKSIZE * blocks; |
208 | c->outptr = c->outbuffer; | |
209 | c->indata_used += BLOCKSIZE * blocks; | |
210 | if (c->indata_used >= sizeof(c->inbuffer)/2) { | |
211 | memmove(c->inbuffer, c->inbuffer + c->indata_used, | |
212 | c->indata - c->indata_used); | |
213 | c->indata -= c->indata_used; | |
214 | c->indata_used = 0; | |
215 | } | |
216 | if (c->eof) { | |
217 | // Remove PKCS7 padding at the end | |
218 | int padding = c->outbuffer[c->outdata - 1]; | |
219 | c->outdata -= padding; | |
220 | } | |
221 | goto retry; | |
222 | } | |
223 | ||
f6fa7814 DM |
224 | static int crypto_write(URLContext *h, const unsigned char *buf, int size) |
225 | { | |
226 | CryptoContext *c = h->priv_data; | |
227 | int total_size, blocks, pad_len, out_size; | |
228 | uint8_t *out_buf; | |
229 | int ret = 0; | |
230 | ||
231 | total_size = size + c->pad_len; | |
232 | pad_len = total_size % BLOCKSIZE; | |
233 | out_size = total_size - pad_len; | |
234 | blocks = out_size / BLOCKSIZE; | |
235 | ||
236 | if (out_size) { | |
237 | out_buf = av_malloc(out_size); | |
238 | if (!out_buf) | |
239 | return AVERROR(ENOMEM); | |
240 | ||
241 | if (c->pad_len) { | |
242 | memcpy(&c->pad[c->pad_len], buf, BLOCKSIZE - c->pad_len); | |
243 | av_aes_crypt(c->aes_encrypt, out_buf, c->pad, 1, c->encrypt_iv, 0); | |
244 | blocks--; | |
245 | } | |
246 | ||
247 | av_aes_crypt(c->aes_encrypt, &out_buf[c->pad_len ? BLOCKSIZE : 0], | |
248 | &buf[c->pad_len ? BLOCKSIZE - c->pad_len: 0], | |
249 | blocks, c->encrypt_iv, 0); | |
250 | ||
251 | ret = ffurl_write(c->hd, out_buf, out_size); | |
252 | av_free(out_buf); | |
253 | if (ret < 0) | |
254 | return ret; | |
255 | ||
256 | memcpy(c->pad, &buf[size - pad_len], pad_len); | |
257 | } else | |
258 | memcpy(&c->pad[c->pad_len], buf, size); | |
259 | ||
260 | c->pad_len = pad_len; | |
261 | ||
262 | return size; | |
263 | } | |
264 | ||
2ba45a60 DM |
265 | static int crypto_close(URLContext *h) |
266 | { | |
267 | CryptoContext *c = h->priv_data; | |
f6fa7814 DM |
268 | uint8_t out_buf[BLOCKSIZE]; |
269 | int ret, pad; | |
270 | ||
271 | if (c->aes_encrypt) { | |
272 | pad = BLOCKSIZE - c->pad_len; | |
273 | memset(&c->pad[c->pad_len], pad, pad); | |
274 | av_aes_crypt(c->aes_encrypt, out_buf, c->pad, 1, c->encrypt_iv, 0); | |
275 | if ((ret = ffurl_write(c->hd, out_buf, BLOCKSIZE)) < 0) | |
276 | return ret; | |
277 | } | |
278 | ||
2ba45a60 DM |
279 | if (c->hd) |
280 | ffurl_close(c->hd); | |
f6fa7814 DM |
281 | av_freep(&c->aes_decrypt); |
282 | av_freep(&c->aes_encrypt); | |
2ba45a60 DM |
283 | return 0; |
284 | } | |
285 | ||
286 | URLProtocol ff_crypto_protocol = { | |
287 | .name = "crypto", | |
288 | .url_open2 = crypto_open2, | |
289 | .url_read = crypto_read, | |
f6fa7814 | 290 | .url_write = crypto_write, |
2ba45a60 DM |
291 | .url_close = crypto_close, |
292 | .priv_data_size = sizeof(CryptoContext), | |
293 | .priv_data_class = &crypto_class, | |
294 | .flags = URL_PROTOCOL_FLAG_NESTED_SCHEME, | |
295 | }; |