ssl/record/dtls1_bitmap.c

   1 /*
   2  * Copyright 2005-2016 The OpenSSL Project Authors. All Rights Reserved.
   3  *
   4  * Licensed under the OpenSSL license (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_locl.h"
  11 #include "record_locl.h"
  12
  13 /* mod 128 saturating subtract of two 64-bit values in big-endian order */
  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
  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
  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 }