1 /*
2 * Copyright 2005-2016 The OpenSSL Project Authors. All Rights Reserved.
3 *
4 * Licensed under the Apache License 2.0 (the "License"). You may not use
5 * this file except in compliance with the License. You can obtain a copy
6 * in the file LICENSE in the source distribution or at
7 * https://www.openssl.org/source/license.html
8 */
9
10 #include "../ssl_local.h"
11 #include "record_local.h"
12
13 /* mod 128 saturating subtract of two 64-bit values in big-endian order */
satsub64be(const unsigned char * v1,const unsigned char * v2)14 static int satsub64be(const unsigned char *v1, const unsigned char *v2)
15 {
16 int64_t ret;
17 uint64_t l1, l2;
18
19 n2l8(v1, l1);
20 n2l8(v2, l2);
21
22 ret = l1 - l2;
23
24 /* We do not permit wrap-around */
25 if (l1 > l2 && ret < 0)
26 return 128;
27 else if (l2 > l1 && ret > 0)
28 return -128;
29
30 if (ret > 128)
31 return 128;
32 else if (ret < -128)
33 return -128;
34 else
35 return (int)ret;
36 }
37
dtls1_record_replay_check(SSL * s,DTLS1_BITMAP * bitmap)38 int dtls1_record_replay_check(SSL *s, DTLS1_BITMAP *bitmap)
39 {
40 int cmp;
41 unsigned int shift;
42 const unsigned char *seq = s->rlayer.read_sequence;
43
44 cmp = satsub64be(seq, bitmap->max_seq_num);
45 if (cmp > 0) {
46 SSL3_RECORD_set_seq_num(RECORD_LAYER_get_rrec(&s->rlayer), seq);
47 return 1; /* this record in new */
48 }
49 shift = -cmp;
50 if (shift >= sizeof(bitmap->map) * 8)
51 return 0; /* stale, outside the window */
52 else if (bitmap->map & (1UL << shift))
53 return 0; /* record previously received */
54
55 SSL3_RECORD_set_seq_num(RECORD_LAYER_get_rrec(&s->rlayer), seq);
56 return 1;
57 }
58
dtls1_record_bitmap_update(SSL * s,DTLS1_BITMAP * bitmap)59 void dtls1_record_bitmap_update(SSL *s, DTLS1_BITMAP *bitmap)
60 {
61 int cmp;
62 unsigned int shift;
63 const unsigned char *seq = RECORD_LAYER_get_read_sequence(&s->rlayer);
64
65 cmp = satsub64be(seq, bitmap->max_seq_num);
66 if (cmp > 0) {
67 shift = cmp;
68 if (shift < sizeof(bitmap->map) * 8)
69 bitmap->map <<= shift, bitmap->map |= 1UL;
70 else
71 bitmap->map = 1UL;
72 memcpy(bitmap->max_seq_num, seq, SEQ_NUM_SIZE);
73 } else {
74 shift = -cmp;
75 if (shift < sizeof(bitmap->map) * 8)
76 bitmap->map |= 1UL << shift;
77 }
78 }
79