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| 1 /* | |
| 2 * rdb.c | |
| 3 * | |
| 4 * Implements a replay database for packet security | |
| 5 * | |
| 6 * David A. McGrew | |
| 7 * Cisco Systems, Inc. | |
| 8 */ | |
| 9 | |
| 10 /* | |
| 11 * | |
| 12 * Copyright (c) 2001-2006, Cisco Systems, Inc. | |
| 13 * All rights reserved. | |
| 14 * | |
| 15 * Redistribution and use in source and binary forms, with or without | |
| 16 * modification, are permitted provided that the following conditions | |
| 17 * are met: | |
| 18 * | |
| 19 * Redistributions of source code must retain the above copyright | |
| 20 * notice, this list of conditions and the following disclaimer. | |
| 21 * | |
| 22 * Redistributions in binary form must reproduce the above | |
| 23 * copyright notice, this list of conditions and the following | |
| 24 * disclaimer in the documentation and/or other materials provided | |
| 25 * with the distribution. | |
| 26 * | |
| 27 * Neither the name of the Cisco Systems, Inc. nor the names of its | |
| 28 * contributors may be used to endorse or promote products derived | |
| 29 * from this software without specific prior written permission. | |
| 30 * | |
| 31 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS | |
| 32 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT | |
| 33 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS | |
| 34 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE | |
| 35 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, | |
| 36 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES | |
| 37 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR | |
| 38 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) | |
| 39 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, | |
| 40 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) | |
| 41 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED | |
| 42 * OF THE POSSIBILITY OF SUCH DAMAGE. | |
| 43 * | |
| 44 */ | |
| 45 | |
| 46 | |
| 47 #ifdef HAVE_CONFIG_H | |
| 48 #include <config.h> | |
| 49 #endif | |
| 50 | |
| 51 #include "rdb.h" | |
| 52 | |
| 53 | |
| 54 /* | |
| 55 * this implementation of a replay database works as follows: | |
| 56 * | |
| 57 * window_start is the index of the first packet in the window | |
| 58 * bitmask a bit-buffer, containing the most recently entered | |
| 59 * index as the leftmost bit | |
| 60 * | |
| 61 */ | |
| 62 | |
| 63 /* rdb_init initalizes rdb */ | |
| 64 | |
| 65 err_status_t | |
| 66 rdb_init(rdb_t *rdb) { | |
| 67 v128_set_to_zero(&rdb->bitmask); | |
| 68 rdb->window_start = 0; | |
| 69 return err_status_ok; | |
| 70 } | |
| 71 | |
| 72 /* | |
| 73 * rdb_check checks to see if index appears in rdb | |
| 74 */ | |
| 75 | |
| 76 err_status_t | |
| 77 rdb_check(const rdb_t *rdb, uint32_t p_index) { | |
| 78 | |
| 79 /* if the index appears after (or at very end of) the window, its good */ | |
| 80 if (p_index >= rdb->window_start + rdb_bits_in_bitmask) | |
| 81 return err_status_ok; | |
| 82 | |
| 83 /* if the index appears before the window, its bad */ | |
| 84 if (p_index < rdb->window_start) | |
| 85 return err_status_replay_old; | |
| 86 | |
| 87 /* otherwise, the index appears within the window, so check the bitmask */ | |
| 88 if (v128_get_bit(&rdb->bitmask, (p_index - rdb->window_start)) == 1) | |
| 89 return err_status_replay_fail; | |
| 90 | |
| 91 /* otherwise, the index is okay */ | |
| 92 return err_status_ok; | |
| 93 } | |
| 94 | |
| 95 /* | |
| 96 * rdb_add_index adds index to rdb_t (and does *not* check if | |
| 97 * index appears in db) | |
| 98 * | |
| 99 * this function should be called only after rdb_check has | |
| 100 * indicated that the index does not appear in the rdb, e.g., a mutex | |
| 101 * should protect the rdb between these calls | |
| 102 */ | |
| 103 | |
| 104 err_status_t | |
| 105 rdb_add_index(rdb_t *rdb, uint32_t p_index) { | |
| 106 int delta; | |
| 107 | |
| 108 /* here we *assume* that p_index > rdb->window_start */ | |
| 109 | |
| 110 delta = (p_index - rdb->window_start); | |
| 111 if (delta < rdb_bits_in_bitmask) { | |
| 112 | |
| 113 /* if the p_index is within the window, set the appropriate bit */ | |
| 114 v128_set_bit(&rdb->bitmask, delta); | |
| 115 | |
| 116 } else { | |
| 117 | |
| 118 delta -= rdb_bits_in_bitmask - 1; | |
| 119 | |
| 120 /* shift the window forward by delta bits*/ | |
| 121 v128_left_shift(&rdb->bitmask, delta); | |
| 122 v128_set_bit(&rdb->bitmask, rdb_bits_in_bitmask-1); | |
| 123 rdb->window_start += delta; | |
| 124 | |
| 125 } | |
| 126 | |
| 127 return err_status_ok; | |
| 128 } | |
| 129 | |
| 130 err_status_t | |
| 131 rdb_increment(rdb_t *rdb) { | |
| 132 | |
| 133 if (rdb->window_start++ > 0x7fffffff) | |
| 134 return err_status_key_expired; | |
| 135 return err_status_ok; | |
| 136 } | |
| 137 | |
| 138 uint32_t | |
| 139 rdb_get_value(const rdb_t *rdb) { | |
| 140 return rdb->window_start; | |
| 141 } | |
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Chromium Code Reviews
Issue 2344973002:
Update libsrtp to version 2.0 (Closed)
