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rtmpcrypt.c
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1 /*
2  * RTMPE network protocol
3  * Copyright (c) 2008-2009 Andrej Stepanchuk
4  * Copyright (c) 2009-2010 Howard Chu
5  * Copyright (c) 2012 Samuel Pitoiset
6  *
7  * This file is part of FFmpeg.
8  *
9  * FFmpeg is free software; you can redistribute it and/or
10  * modify it under the terms of the GNU Lesser General Public
11  * License as published by the Free Software Foundation; either
12  * version 2.1 of the License, or (at your option) any later version.
13  *
14  * FFmpeg is distributed in the hope that it will be useful,
15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
17  * Lesser General Public License for more details.
18  *
19  * You should have received a copy of the GNU Lesser General Public
20  * License along with FFmpeg; if not, write to the Free Software
21  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
22  */
23 
24 /**
25  * @file
26  * RTMPE protocol
27  */
28 
29 #include "libavutil/blowfish.h"
30 #include "libavutil/intreadwrite.h"
31 #include "libavutil/opt.h"
32 #include "libavutil/rc4.h"
33 #include "libavutil/xtea.h"
34 
35 #include "internal.h"
36 #include "rtmp.h"
37 #include "rtmpdh.h"
38 #include "rtmpcrypt.h"
39 #include "url.h"
40 
41 /* protocol handler context */
42 typedef struct RTMPEContext {
43  const AVClass *class;
44  URLContext *stream; ///< TCP stream
45  FF_DH *dh; ///< Diffie-Hellman context
46  struct AVRC4 key_in; ///< RC4 key used for decrypt data
47  struct AVRC4 key_out; ///< RC4 key used for encrypt data
48  int handshaked; ///< flag indicating when the handshake is performed
49  int tunneling; ///< use a HTTP connection (RTMPTE)
50 } RTMPEContext;
51 
52 static const uint8_t rtmpe8_keys[16][16] = {
53  { 0xbf, 0xf0, 0x34, 0xb2, 0x11, 0xd9, 0x08, 0x1f,
54  0xcc, 0xdf, 0xb7, 0x95, 0x74, 0x8d, 0xe7, 0x32 },
55  { 0x08, 0x6a, 0x5e, 0xb6, 0x17, 0x43, 0x09, 0x0e,
56  0x6e, 0xf0, 0x5a, 0xb8, 0xfe, 0x5a, 0x39, 0xe2 },
57  { 0x7b, 0x10, 0x95, 0x6f, 0x76, 0xce, 0x05, 0x21,
58  0x23, 0x88, 0xa7, 0x3a, 0x44, 0x01, 0x49, 0xa1 },
59  { 0xa9, 0x43, 0xf3, 0x17, 0xeb, 0xf1, 0x1b, 0xb2,
60  0xa6, 0x91, 0xa5, 0xee, 0x17, 0xf3, 0x63, 0x39 },
61  { 0x7a, 0x30, 0xe0, 0x0a, 0xb5, 0x29, 0xe2, 0x2c,
62  0xa0, 0x87, 0xae, 0xa5, 0xc0, 0xcb, 0x79, 0xac },
63  { 0xbd, 0xce, 0x0c, 0x23, 0x2f, 0xeb, 0xde, 0xff,
64  0x1c, 0xfa, 0xae, 0x16, 0x11, 0x23, 0x23, 0x9d },
65  { 0x55, 0xdd, 0x3f, 0x7b, 0x77, 0xe7, 0xe6, 0x2e,
66  0x9b, 0xb8, 0xc4, 0x99, 0xc9, 0x48, 0x1e, 0xe4 },
67  { 0x40, 0x7b, 0xb6, 0xb4, 0x71, 0xe8, 0x91, 0x36,
68  0xa7, 0xae, 0xbf, 0x55, 0xca, 0x33, 0xb8, 0x39 },
69  { 0xfc, 0xf6, 0xbd, 0xc3, 0xb6, 0x3c, 0x36, 0x97,
70  0x7c, 0xe4, 0xf8, 0x25, 0x04, 0xd9, 0x59, 0xb2 },
71  { 0x28, 0xe0, 0x91, 0xfd, 0x41, 0x95, 0x4c, 0x4c,
72  0x7f, 0xb7, 0xdb, 0x00, 0xe3, 0xa0, 0x66, 0xf8 },
73  { 0x57, 0x84, 0x5b, 0x76, 0x4f, 0x25, 0x1b, 0x03,
74  0x46, 0xd4, 0x5b, 0xcd, 0xa2, 0xc3, 0x0d, 0x29 },
75  { 0x0a, 0xcc, 0xee, 0xf8, 0xda, 0x55, 0xb5, 0x46,
76  0x03, 0x47, 0x34, 0x52, 0x58, 0x63, 0x71, 0x3b },
77  { 0xb8, 0x20, 0x75, 0xdc, 0xa7, 0x5f, 0x1f, 0xee,
78  0xd8, 0x42, 0x68, 0xe8, 0xa7, 0x2a, 0x44, 0xcc },
79  { 0x07, 0xcf, 0x6e, 0x9e, 0xa1, 0x6d, 0x7b, 0x25,
80  0x9f, 0xa7, 0xae, 0x6c, 0xd9, 0x2f, 0x56, 0x29 },
81  { 0xfe, 0xb1, 0xea, 0xe4, 0x8c, 0x8c, 0x3c, 0xe1,
82  0x4e, 0x00, 0x64, 0xa7, 0x6a, 0x38, 0x7c, 0x2a },
83  { 0x89, 0x3a, 0x94, 0x27, 0xcc, 0x30, 0x13, 0xa2,
84  0xf1, 0x06, 0x38, 0x5b, 0xa8, 0x29, 0xf9, 0x27 }
85 };
86 
87 static const uint8_t rtmpe9_keys[16][24] = {
88  { 0x79, 0x34, 0x77, 0x4c, 0x67, 0xd1, 0x38, 0x3a, 0xdf, 0xb3, 0x56, 0xbe,
89  0x8b, 0x7b, 0xd0, 0x24, 0x38, 0xe0, 0x73, 0x58, 0x41, 0x5d, 0x69, 0x67, },
90  { 0x46, 0xf6, 0xb4, 0xcc, 0x01, 0x93, 0xe3, 0xa1, 0x9e, 0x7d, 0x3c, 0x65,
91  0x55, 0x86, 0xfd, 0x09, 0x8f, 0xf7, 0xb3, 0xc4, 0x6f, 0x41, 0xca, 0x5c, },
92  { 0x1a, 0xe7, 0xe2, 0xf3, 0xf9, 0x14, 0x79, 0x94, 0xc0, 0xd3, 0x97, 0x43,
93  0x08, 0x7b, 0xb3, 0x84, 0x43, 0x2f, 0x9d, 0x84, 0x3f, 0x21, 0x01, 0x9b, },
94  { 0xd3, 0xe3, 0x54, 0xb0, 0xf7, 0x1d, 0xf6, 0x2b, 0x5a, 0x43, 0x4d, 0x04,
95  0x83, 0x64, 0x3e, 0x0d, 0x59, 0x2f, 0x61, 0xcb, 0xb1, 0x6a, 0x59, 0x0d, },
96  { 0xc8, 0xc1, 0xe9, 0xb8, 0x16, 0x56, 0x99, 0x21, 0x7b, 0x5b, 0x36, 0xb7,
97  0xb5, 0x9b, 0xdf, 0x06, 0x49, 0x2c, 0x97, 0xf5, 0x95, 0x48, 0x85, 0x7e, },
98  { 0xeb, 0xe5, 0xe6, 0x2e, 0xa4, 0xba, 0xd4, 0x2c, 0xf2, 0x16, 0xe0, 0x8f,
99  0x66, 0x23, 0xa9, 0x43, 0x41, 0xce, 0x38, 0x14, 0x84, 0x95, 0x00, 0x53, },
100  { 0x66, 0xdb, 0x90, 0xf0, 0x3b, 0x4f, 0xf5, 0x6f, 0xe4, 0x9c, 0x20, 0x89,
101  0x35, 0x5e, 0xd2, 0xb2, 0xc3, 0x9e, 0x9f, 0x7f, 0x63, 0xb2, 0x28, 0x81, },
102  { 0xbb, 0x20, 0xac, 0xed, 0x2a, 0x04, 0x6a, 0x19, 0x94, 0x98, 0x9b, 0xc8,
103  0xff, 0xcd, 0x93, 0xef, 0xc6, 0x0d, 0x56, 0xa7, 0xeb, 0x13, 0xd9, 0x30, },
104  { 0xbc, 0xf2, 0x43, 0x82, 0x09, 0x40, 0x8a, 0x87, 0x25, 0x43, 0x6d, 0xe6,
105  0xbb, 0xa4, 0xb9, 0x44, 0x58, 0x3f, 0x21, 0x7c, 0x99, 0xbb, 0x3f, 0x24, },
106  { 0xec, 0x1a, 0xaa, 0xcd, 0xce, 0xbd, 0x53, 0x11, 0xd2, 0xfb, 0x83, 0xb6,
107  0xc3, 0xba, 0xab, 0x4f, 0x62, 0x79, 0xe8, 0x65, 0xa9, 0x92, 0x28, 0x76, },
108  { 0xc6, 0x0c, 0x30, 0x03, 0x91, 0x18, 0x2d, 0x7b, 0x79, 0xda, 0xe1, 0xd5,
109  0x64, 0x77, 0x9a, 0x12, 0xc5, 0xb1, 0xd7, 0x91, 0x4f, 0x96, 0x4c, 0xa3, },
110  { 0xd7, 0x7c, 0x2a, 0xbf, 0xa6, 0xe7, 0x85, 0x7c, 0x45, 0xad, 0xff, 0x12,
111  0x94, 0xd8, 0xde, 0xa4, 0x5c, 0x3d, 0x79, 0xa4, 0x44, 0x02, 0x5d, 0x22, },
112  { 0x16, 0x19, 0x0d, 0x81, 0x6a, 0x4c, 0xc7, 0xf8, 0xb8, 0xf9, 0x4e, 0xcd,
113  0x2c, 0x9e, 0x90, 0x84, 0xb2, 0x08, 0x25, 0x60, 0xe1, 0x1e, 0xae, 0x18, },
114  { 0xe9, 0x7c, 0x58, 0x26, 0x1b, 0x51, 0x9e, 0x49, 0x82, 0x60, 0x61, 0xfc,
115  0xa0, 0xa0, 0x1b, 0xcd, 0xf5, 0x05, 0xd6, 0xa6, 0x6d, 0x07, 0x88, 0xa3, },
116  { 0x2b, 0x97, 0x11, 0x8b, 0xd9, 0x4e, 0xd9, 0xdf, 0x20, 0xe3, 0x9c, 0x10,
117  0xe6, 0xa1, 0x35, 0x21, 0x11, 0xf9, 0x13, 0x0d, 0x0b, 0x24, 0x65, 0xb2, },
118  { 0x53, 0x6a, 0x4c, 0x54, 0xac, 0x8b, 0x9b, 0xb8, 0x97, 0x29, 0xfc, 0x60,
119  0x2c, 0x5b, 0x3a, 0x85, 0x68, 0xb5, 0xaa, 0x6a, 0x44, 0xcd, 0x3f, 0xa7, },
120 };
121 
123 {
124  RTMPEContext *rt = h->priv_data;
125  int offset, ret;
126 
127  if (!(rt->dh = ff_dh_init(1024)))
128  return AVERROR(ENOMEM);
129 
130  offset = ff_rtmp_calc_digest_pos(buf, 768, 632, 8);
131  if (offset < 0)
132  return offset;
133 
134  /* generate a Diffie-Hellmann public key */
135  if ((ret = ff_dh_generate_public_key(rt->dh)) < 0)
136  return ret;
137 
138  /* write the public key into the handshake buffer */
139  if ((ret = ff_dh_write_public_key(rt->dh, buf + offset, 128)) < 0)
140  return ret;
141 
142  return 0;
143 }
144 
146  const uint8_t *clientdata, int type)
147 {
148  RTMPEContext *rt = h->priv_data;
149  uint8_t secret_key[128], digest[32];
150  int server_pos, client_pos;
151  int ret;
152 
153  if (type) {
154  if ((server_pos = ff_rtmp_calc_digest_pos(serverdata, 1532, 632, 772)) < 0)
155  return server_pos;
156  } else {
157  if ((server_pos = ff_rtmp_calc_digest_pos(serverdata, 768, 632, 8)) < 0)
158  return server_pos;
159  }
160 
161  if ((client_pos = ff_rtmp_calc_digest_pos(clientdata, 768, 632, 8)) < 0)
162  return client_pos;
163 
164  /* compute the shared secret secret in order to compute RC4 keys */
165  if ((ret = ff_dh_compute_shared_secret_key(rt->dh, serverdata + server_pos,
166  128, secret_key)) < 0)
167  return ret;
168 
169  /* set output key */
170  if ((ret = ff_rtmp_calc_digest(serverdata + server_pos, 128, 0, secret_key,
171  128, digest)) < 0)
172  return ret;
173  av_rc4_init(&rt->key_out, digest, 16 * 8, 1);
174 
175  /* set input key */
176  if ((ret = ff_rtmp_calc_digest(clientdata + client_pos, 128, 0, secret_key,
177  128, digest)) < 0)
178  return ret;
179  av_rc4_init(&rt->key_in, digest, 16 * 8, 1);
180 
181  return 0;
182 }
183 
184 static void rtmpe8_sig(const uint8_t *in, uint8_t *out, int key_id)
185 {
186  struct AVXTEA ctx;
187 
188  av_xtea_init(&ctx, rtmpe8_keys[key_id]);
189  av_xtea_crypt(&ctx, out, in, 1, NULL, 0);
190 }
191 
192 static void rtmpe9_sig(const uint8_t *in, uint8_t *out, int key_id)
193 {
194  struct AVBlowfish ctx;
195  uint32_t xl, xr;
196 
197  xl = AV_RL32(in);
198  xr = AV_RL32(in + 4);
199 
200  av_blowfish_init(&ctx, rtmpe9_keys[key_id], 24);
201  av_blowfish_crypt_ecb(&ctx, &xl, &xr, 0);
202 
203  AV_WL32(out, xl);
204  AV_WL32(out + 4, xr);
205 }
206 
207 void ff_rtmpe_encrypt_sig(URLContext *h, uint8_t *sig, const uint8_t *digest,
208  int type)
209 {
210  int i;
211 
212  for (i = 0; i < 32; i += 8) {
213  if (type == 8) {
214  /* RTMPE type 8 uses XTEA on the signature */
215  rtmpe8_sig(sig + i, sig + i, digest[i] % 15);
216  } else if (type == 9) {
217  /* RTMPE type 9 uses Blowfish on the signature */
218  rtmpe9_sig(sig + i, sig + i, digest[i] % 15);
219  }
220  }
221 }
222 
224 {
225  RTMPEContext *rt = h->priv_data;
227 
228  /* skip past 1536 bytes of the RC4 bytestream */
229  av_rc4_crypt(&rt->key_in, buf, NULL, sizeof(buf), NULL, 1);
230  av_rc4_crypt(&rt->key_out, buf, NULL, sizeof(buf), NULL, 1);
231 
232  /* the next requests will be encrypted using RC4 keys */
233  rt->handshaked = 1;
234 
235  return 0;
236 }
237 
238 static int rtmpe_close(URLContext *h)
239 {
240  RTMPEContext *rt = h->priv_data;
241 
242  ff_dh_free(rt->dh);
243  ffurl_close(rt->stream);
244 
245  return 0;
246 }
247 
248 static int rtmpe_open(URLContext *h, const char *uri, int flags)
249 {
250  RTMPEContext *rt = h->priv_data;
251  char host[256], url[1024];
252  int ret, port;
253 
254  av_url_split(NULL, 0, NULL, 0, host, sizeof(host), &port, NULL, 0, uri);
255 
256  if (rt->tunneling) {
257  if (port < 0)
258  port = 80;
259  ff_url_join(url, sizeof(url), "ffrtmphttp", NULL, host, port, NULL);
260  } else {
261  if (port < 0)
262  port = 1935;
263  ff_url_join(url, sizeof(url), "tcp", NULL, host, port, NULL);
264  }
265 
266  /* open the tcp or ffrtmphttp connection */
267  if ((ret = ffurl_open(&rt->stream, url, AVIO_FLAG_READ_WRITE,
268  &h->interrupt_callback, NULL)) < 0) {
269  rtmpe_close(h);
270  return ret;
271  }
272 
273  return 0;
274 }
275 
276 static int rtmpe_read(URLContext *h, uint8_t *buf, int size)
277 {
278  RTMPEContext *rt = h->priv_data;
279  int ret;
280 
281  rt->stream->flags |= h->flags & AVIO_FLAG_NONBLOCK;
282  ret = ffurl_read(rt->stream, buf, size);
284 
285  if (ret < 0 && ret != AVERROR_EOF)
286  return ret;
287 
288  if (rt->handshaked && ret > 0) {
289  /* decrypt data received by the server */
290  av_rc4_crypt(&rt->key_in, buf, buf, ret, NULL, 1);
291  }
292 
293  return ret;
294 }
295 
296 static int rtmpe_write(URLContext *h, const uint8_t *buf, int size)
297 {
298  RTMPEContext *rt = h->priv_data;
299  int ret;
300 
301  if (rt->handshaked) {
302  /* encrypt data to send to the server */
303  av_rc4_crypt(&rt->key_out, buf, buf, size, NULL, 1);
304  }
305 
306  if ((ret = ffurl_write(rt->stream, buf, size)) < 0)
307  return ret;
308 
309  return size;
310 }
311 
312 #define OFFSET(x) offsetof(RTMPEContext, x)
313 #define DEC AV_OPT_FLAG_DECODING_PARAM
314 
315 static const AVOption ffrtmpcrypt_options[] = {
316  {"ffrtmpcrypt_tunneling", "Use a HTTP tunneling connection (RTMPTE).", OFFSET(tunneling), AV_OPT_TYPE_INT, {.i64 = 0}, 0, 1, DEC},
317  { NULL },
318 };
319 
320 static const AVClass ffrtmpcrypt_class = {
321  .class_name = "ffrtmpcrypt",
322  .item_name = av_default_item_name,
323  .option = ffrtmpcrypt_options,
324  .version = LIBAVUTIL_VERSION_INT,
325 };
326 
328  .name = "ffrtmpcrypt",
329  .url_open = rtmpe_open,
330  .url_read = rtmpe_read,
331  .url_write = rtmpe_write,
332  .url_close = rtmpe_close,
333  .priv_data_size = sizeof(RTMPEContext),
335  .priv_data_class = &ffrtmpcrypt_class,
336 };