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