summaryrefslogtreecommitdiff
path: root/src/mongo/util/secure_compare_memory.cpp
blob: 1f22de564331a4dc1d5d2afd518a7ed7b6d14a04 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
/*    Copyright 2017 MongoDB Inc.
 *
 *    This program is free software: you can redistribute it and/or  modify
 *    it under the terms of the GNU Affero General Public License, version 3,
 *    as published by the Free Software Foundation.
 *
 *    This program is distributed in the hope that it will be useful,
 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *    GNU Affero General Public License for more details.
 *
 *    You should have received a copy of the GNU Affero General Public License
 *    along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 *    As a special exception, the copyright holders give permission to link the
 *    code of portions of this program with the OpenSSL library under certain
 *    conditions as described in each individual source file and distribute
 *    linked combinations including the program with the OpenSSL library. You
 *    must comply with the GNU Affero General Public License in all respects
 *    for all of the code used other than as permitted herein. If you modify
 *    file(s) with this exception, you may extend this exception to your
 *    version of the file(s), but you are not obligated to do so. If you do not
 *    wish to do so, delete this exception statement from your version. If you
 *    delete this exception statement from all source files in the program,
 *    then also delete it in the license file.
 */


#include "mongo/platform/basic.h"

#include "mongo/util/secure_compare_memory.h"

namespace mongo {

bool consttimeMemEqual(volatile const unsigned char* s1,  // NOLINT - using volatile to
                       volatile const unsigned char* s2,  // NOLINT - disable compiler optimizations
                       size_t length) {
    unsigned int ret = 0;

    for (size_t i = 0; i < length; ++i) {
        ret |= s1[i] ^ s2[i];
    }

    return (1 & ((ret - 1) >> 8));
}

}  // namespace mongo