1 /*
2 * key.c
3 *
4 * key usage limits enforcement
5 *
6 * David A. Mcgrew
7 * Cisco Systems, Inc.
8 */
9 /*
10 *
11 * Copyright (c) 2001-2017 Cisco Systems, Inc.
12 * All rights reserved.
13 *
14 * Redistribution and use in source and binary forms, with or without
15 * modification, are permitted provided that the following conditions
16 * are met:
17 *
18 * Redistributions of source code must retain the above copyright
19 * notice, this list of conditions and the following disclaimer.
20 *
21 * Redistributions in binary form must reproduce the above
22 * copyright notice, this list of conditions and the following
23 * disclaimer in the documentation and/or other materials provided
24 * with the distribution.
25 *
26 * Neither the name of the Cisco Systems, Inc. nor the names of its
27 * contributors may be used to endorse or promote products derived
28 * from this software without specific prior written permission.
29 *
30 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
31 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
32 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
33 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
34 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
35 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
36 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
37 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
38 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
39 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
40 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
41 * OF THE POSSIBILITY OF SUCH DAMAGE.
42 *
43 */
44
45 #ifdef HAVE_CONFIG_H
46 #include <config.h>
47 #endif
48
49 #include "key.h"
50
51 #define soft_limit 0x10000
52
srtp_key_limit_set(srtp_key_limit_t key,const srtp_xtd_seq_num_t s)53 srtp_err_status_t srtp_key_limit_set(srtp_key_limit_t key,
54 const srtp_xtd_seq_num_t s)
55 {
56 #ifdef NO_64BIT_MATH
57 if (high32(s) == 0 && low32(s) < soft_limit) {
58 return srtp_err_status_bad_param;
59 }
60 #else
61 if (s < soft_limit) {
62 return srtp_err_status_bad_param;
63 }
64 #endif
65 key->num_left = s;
66 key->state = srtp_key_state_normal;
67 return srtp_err_status_ok;
68 }
69
srtp_key_limit_clone(srtp_key_limit_t original,srtp_key_limit_t * new_key)70 srtp_err_status_t srtp_key_limit_clone(srtp_key_limit_t original,
71 srtp_key_limit_t *new_key)
72 {
73 if (original == NULL) {
74 return srtp_err_status_bad_param;
75 }
76 *new_key = original;
77 return srtp_err_status_ok;
78 }
79
srtp_key_limit_check(const srtp_key_limit_t key)80 srtp_err_status_t srtp_key_limit_check(const srtp_key_limit_t key)
81 {
82 if (key->state == srtp_key_state_expired) {
83 return srtp_err_status_key_expired;
84 }
85 return srtp_err_status_ok;
86 }
87
srtp_key_limit_update(srtp_key_limit_t key)88 srtp_key_event_t srtp_key_limit_update(srtp_key_limit_t key)
89 {
90 #ifdef NO_64BIT_MATH
91 if (low32(key->num_left) == 0) {
92 // carry
93 key->num_left =
94 make64(high32(key->num_left) - 1, low32(key->num_left) - 1);
95 } else {
96 // no carry
97 key->num_left = make64(high32(key->num_left), low32(key->num_left) - 1);
98 }
99 if (high32(key->num_left) != 0 || low32(key->num_left) >= soft_limit) {
100 return srtp_key_event_normal; /* we're above the soft limit */
101 }
102 #else
103 key->num_left--;
104 if (key->num_left >= soft_limit) {
105 return srtp_key_event_normal; /* we're above the soft limit */
106 }
107 #endif
108 if (key->state == srtp_key_state_normal) {
109 /* we just passed the soft limit, so change the state */
110 key->state = srtp_key_state_past_soft_limit;
111 }
112 #ifdef NO_64BIT_MATH
113 if (low32(key->num_left) == 0 && high32(key->num_left == 0))
114 #else
115 if (key->num_left < 1)
116 #endif
117 { /* we just hit the hard limit */
118 key->state = srtp_key_state_expired;
119 return srtp_key_event_hard_limit;
120 }
121 return srtp_key_event_soft_limit;
122 }
123