The Tor Browser: netwerk/srtp/src/crypto/replay/rdb.c@6474c204b198

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

     1 /*

     2  * rdb.c

     3  *

     4  * Implements a replay database for packet security

     5  *

     6  * David A. McGrew

     7  * Cisco Systems, Inc.

     8  */

    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  */

    47 #include "rdb.h"

    50 /*

    51  * this implementation of a replay database works as follows:

    52  *

    53  * window_start is the index of the first packet in the window

    54  * bitmask      a bit-buffer, containing the most recently entered

    55  *              index as the leftmost bit

    56  *

    57  */

    59 /* rdb_init initalizes rdb */

    61 err_status_t

    62 rdb_init(rdb_t *rdb) {

    63   v128_set_to_zero(&rdb->bitmask);

    64   rdb->window_start = 0;

    65   return err_status_ok;

    66 }

    68 /*

    69  * rdb_check checks to see if index appears in rdb

    70  */

    72 err_status_t

    73 rdb_check(const rdb_t *rdb, uint32_t p_index) {

    75   /* if the index appears after (or at very end of) the window, its good */

    76   if (p_index >= rdb->window_start + rdb_bits_in_bitmask)

    77     return err_status_ok;

    79   /* if the index appears before the window, its bad */

    80   if (p_index < rdb->window_start)

    81     return err_status_replay_old;

    83   /* otherwise, the index appears within the window, so check the bitmask */

    84   if (v128_get_bit(&rdb->bitmask, (p_index - rdb->window_start)) == 1)

    85     return err_status_replay_fail;

    87   /* otherwise, the index is okay */

    88   return err_status_ok;

    89 }

    91 /*

    92  * rdb_add_index adds index to rdb_t (and does *not* check if

    93  * index appears in db)

    94  *

    95  * this function should be called only after rdb_check has

    96  * indicated that the index does not appear in the rdb, e.g., a mutex

    97  * should protect the rdb between these calls

    98  */

   100 err_status_t

   101 rdb_add_index(rdb_t *rdb, uint32_t p_index) {

   102   int delta;

   104   /* here we *assume* that p_index > rdb->window_start */

   106   delta = (p_index - rdb->window_start);

   107   if (delta < (int)rdb_bits_in_bitmask) {

   109     /* if the p_index is within the window, set the appropriate bit */

   110     v128_set_bit(&rdb->bitmask, delta);

   112   } else {

   114     delta -= rdb_bits_in_bitmask - 1;

   116     /* shift the window forward by delta bits*/

   117     v128_left_shift(&rdb->bitmask, delta);

   118     v128_set_bit(&rdb->bitmask, rdb_bits_in_bitmask-1);

   119     rdb->window_start += delta;

   121   }

   123   return err_status_ok;

   124 }

   126 err_status_t

   127 rdb_increment(rdb_t *rdb) {

   129   if (rdb->window_start++ > 0x7fffffff)

   130     return err_status_key_expired;

   131   return err_status_ok;

   132 }

   134 uint32_t

   135 rdb_get_value(const rdb_t *rdb) {

   136   return rdb->window_start;

   137 }

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