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/*
* Copyright 2005-2016 The OpenSSL Project Authors. All Rights Reserved.
*
* Licensed under the OpenSSL license (the "License"). You may not use
* this file except in compliance with the License. You can obtain a copy
* in the file LICENSE in the source distribution or at
* https://www.openssl.org/source/license.html
*/
#include "../ssl_locl.h"
#include "record_locl.h"
/* mod 128 saturating subtract of two 64-bit values in big-endian order */
static int satsub64be(const unsigned char *v1, const unsigned char *v2)
{
int ret, sat, brw, i;
if (sizeof(long) == 8)
do {
const union {
long one;
char little;
} is_endian = {
1
};
long l;
if (is_endian.little)
break;
/* not reached on little-endians */
/*
* following test is redundant, because input is always aligned,
* but I take no chances...
*/
if (((size_t)v1 | (size_t)v2) & 0x7)
break;
l = *((long *)v1);
l -= *((long *)v2);
if (l > 128)
return 128;
else if (l < -128)
return -128;
else
return (int)l;
} while (0);
ret = (int)v1[7] - (int)v2[7];
sat = 0;
brw = ret >> 8; /* brw is either 0 or -1 */
if (ret & 0x80) {
for (i = 6; i >= 0; i--) {
brw += (int)v1[i] - (int)v2[i];
sat |= ~brw;
brw >>= 8;
}
} else {
for (i = 6; i >= 0; i--) {
brw += (int)v1[i] - (int)v2[i];
sat |= brw;
brw >>= 8;
}
}
brw <<= 8; /* brw is either 0 or -256 */
if (sat & 0xff)
return brw | 0x80;
else
return brw + (ret & 0xFF);
}
int dtls1_record_replay_check(SSL *s, DTLS1_BITMAP *bitmap)
{
int cmp;
unsigned int shift;
const unsigned char *seq = s->rlayer.read_sequence;
cmp = satsub64be(seq, bitmap->max_seq_num);
if (cmp > 0) {
SSL3_RECORD_set_seq_num(RECORD_LAYER_get_rrec(&s->rlayer), seq);
return 1; /* this record in new */
}
shift = -cmp;
if (shift >= sizeof(bitmap->map) * 8)
return 0; /* stale, outside the window */
else if (bitmap->map & (1UL << shift))
return 0; /* record previously received */
SSL3_RECORD_set_seq_num(RECORD_LAYER_get_rrec(&s->rlayer), seq);
return 1;
}
void dtls1_record_bitmap_update(SSL *s, DTLS1_BITMAP *bitmap)
{
int cmp;
unsigned int shift;
const unsigned char *seq = RECORD_LAYER_get_read_sequence(&s->rlayer);
cmp = satsub64be(seq, bitmap->max_seq_num);
if (cmp > 0) {
shift = cmp;
if (shift < sizeof(bitmap->map) * 8)
bitmap->map <<= shift, bitmap->map |= 1UL;
else
bitmap->map = 1UL;
memcpy(bitmap->max_seq_num, seq, SEQ_NUM_SIZE);
} else {
shift = -cmp;
if (shift < sizeof(bitmap->map) * 8)
bitmap->map |= 1UL << shift;
}
}
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