1/*
2 * RTMP network protocol
3 * Copyright (c) 2009 Konstantin Shishkov
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/**
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
34int 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
57int 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}
68