rtmp: Move RTMP digest calculation to a separate file
[libav.git] / libavformat / rtmpdigest.c
1 /*
2 * RTMP network protocol
3 * Copyright (c) 2009 Konstantin Shishkov
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 /**
23 * @file
24 * RTMP protocol digest
25 */
26
27 #include <stdint.h>
28
29 #include "libavutil/error.h"
30 #include "libavutil/hmac.h"
31
32 #include "rtmp.h"
33
34 int ff_rtmp_calc_digest(const uint8_t *src, int len, int gap,
35 const uint8_t *key, int keylen, uint8_t *dst)
36 {
37 AVHMAC *hmac;
38
39 hmac = av_hmac_alloc(AV_HMAC_SHA256);
40 if (!hmac)
41 return AVERROR(ENOMEM);
42
43 av_hmac_init(hmac, key, keylen);
44 if (gap <= 0) {
45 av_hmac_update(hmac, src, len);
46 } else { //skip 32 bytes used for storing digest
47 av_hmac_update(hmac, src, gap);
48 av_hmac_update(hmac, src + gap + 32, len - gap - 32);
49 }
50 av_hmac_final(hmac, dst, 32);
51
52 av_hmac_free(hmac);
53
54 return 0;
55 }
56
57 int ff_rtmp_calc_digest_pos(const uint8_t *buf, int off, int mod_val,
58 int add_val)
59 {
60 int i, digest_pos = 0;
61
62 for (i = 0; i < 4; i++)
63 digest_pos += buf[i + off];
64 digest_pos = digest_pos % mod_val + add_val;
65
66 return digest_pos;
67 }