1 /*
2 * Copyright (c) 2019, The OpenThread Authors.
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions are met:
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 * 3. Neither the name of the copyright holder nor the
13 * names of its contributors may be used to endorse or promote products
14 * derived from this software without specific prior written permission.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
17 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
20 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
21 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
22 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
23 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
24 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
25 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
26 * POSSIBILITY OF SUCH DAMAGE.
27 */
28
29 /**
30 * @file
31 * This file implements an entropy source based on /dev/urandom or pseudo-random generator.
32 *
33 */
34
35 #include "openthread-posix-config.h"
36 #include "platform-posix.h"
37
38 #include <assert.h>
39 #include <stdio.h>
40
41 #include <openthread/error.h>
42 #include <openthread/platform/entropy.h>
43
44 #include "common/code_utils.hpp"
45
46 #ifndef __SANITIZE_ADDRESS__
47 #define __SANITIZE_ADDRESS__ 0
48 #endif
49
50 #if __SANITIZE_ADDRESS__ != 0
51
52 static uint32_t sState = 1;
53
54 #endif // __SANITIZE_ADDRESS__
55
platformRandomInit(void)56 void platformRandomInit(void)
57 {
58 #if __SANITIZE_ADDRESS__ != 0
59
60 // Multiplying gNodeId assures that no two nodes gets the same seed within an hour.
61 sState = (uint32_t)time(nullptr) + (3600 * gNodeId);
62
63 #endif // __SANITIZE_ADDRESS__
64 }
65
66 #if __SANITIZE_ADDRESS__ != 0
67
randomUint32Get(void)68 uint32_t randomUint32Get(void)
69 {
70 uint32_t mlcg, p, q;
71 uint64_t tmpstate;
72
73 tmpstate = (uint64_t)33614 * (uint64_t)sState;
74 q = tmpstate & 0xffffffff;
75 q = q >> 1;
76 p = tmpstate >> 32;
77 mlcg = p + q;
78
79 if (mlcg & 0x80000000)
80 {
81 mlcg &= 0x7fffffff;
82 mlcg++;
83 }
84
85 sState = mlcg;
86
87 return mlcg;
88 }
89
90 #endif // __SANITIZE_ADDRESS__
91
otPlatEntropyGet(uint8_t * aOutput,uint16_t aOutputLength)92 otError otPlatEntropyGet(uint8_t *aOutput, uint16_t aOutputLength)
93 {
94 otError error = OT_ERROR_NONE;
95
96 #if __SANITIZE_ADDRESS__ == 0
97
98 FILE *file = nullptr;
99 size_t readLength;
100
101 VerifyOrExit(aOutput && aOutputLength, error = OT_ERROR_INVALID_ARGS);
102
103 file = fopen("/dev/urandom", "rb");
104 VerifyOrExit(file != nullptr, error = OT_ERROR_FAILED);
105
106 readLength = fread(aOutput, 1, aOutputLength, file);
107 VerifyOrExit(readLength == aOutputLength, error = OT_ERROR_FAILED);
108
109 exit:
110
111 if (file != nullptr)
112 {
113 fclose(file);
114 }
115
116 #else // __SANITIZE_ADDRESS__
117
118 /*
119 * THE IMPLEMENTATION BELOW IS NOT COMPLIANT WITH THE THREAD SPECIFICATION.
120 *
121 * Address Sanitizer triggers test failures when reading random
122 * values from /dev/urandom. The pseudo-random number generator
123 * implementation below is only used to enable continuous
124 * integration checks with Address Sanitizer enabled.
125 */
126 VerifyOrExit(aOutput && aOutputLength, error = OT_ERROR_INVALID_ARGS);
127
128 for (uint16_t length = 0; length < aOutputLength; length++)
129 {
130 aOutput[length] = (uint8_t)randomUint32Get();
131 }
132
133 exit:
134
135 #endif // __SANITIZE_ADDRESS__
136
137 return error;
138 }
139
