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 #include "platform-simulation.h"
35
36 #include <assert.h>
37 #include <stdio.h>
38
39 #include <openthread/platform/entropy.h>
40
41 #include "utils/code_utils.h"
42
43 #ifndef __SANITIZE_ADDRESS__
44 #define __SANITIZE_ADDRESS__ 0
45 #endif
46
47 #if __SANITIZE_ADDRESS__ != 0
48
49 static uint32_t sState = 1;
50
51 #endif // __SANITIZE_ADDRESS__
52
platformRandomInit(void)53 void platformRandomInit(void)
54 {
55 #if __SANITIZE_ADDRESS__ != 0
56
57 // Multiplying gNodeId assures that no two nodes gets the same seed within an hour.
58 sState = (uint32_t)time(NULL) + (3600 * gNodeId);
59
60 #endif // __SANITIZE_ADDRESS__
61 }
62
63 #if __SANITIZE_ADDRESS__ != 0
64
randomUint32Get(void)65 static uint32_t randomUint32Get(void)
66 {
67 uint32_t mlcg, p, q;
68 uint64_t tmpstate;
69
70 tmpstate = (uint64_t)33614 * (uint64_t)sState;
71 q = tmpstate & 0xffffffff;
72 q = q >> 1;
73 p = tmpstate >> 32;
74 mlcg = p + q;
75
76 if (mlcg & 0x80000000)
77 {
78 mlcg &= 0x7fffffff;
79 mlcg++;
80 }
81
82 sState = mlcg;
83
84 return mlcg;
85 }
86
87 #endif // __SANITIZE_ADDRESS__
88
otPlatEntropyGet(uint8_t * aOutput,uint16_t aOutputLength)89 otError otPlatEntropyGet(uint8_t *aOutput, uint16_t aOutputLength)
90 {
91 otError error = OT_ERROR_NONE;
92
93 #if __SANITIZE_ADDRESS__ == 0
94
95 FILE *file = NULL;
96 size_t readLength;
97
98 otEXPECT_ACTION(aOutput && aOutputLength, error = OT_ERROR_INVALID_ARGS);
99
100 file = fopen("/dev/urandom", "rb");
101 otEXPECT_ACTION(file != NULL, error = OT_ERROR_FAILED);
102
103 readLength = fread(aOutput, 1, aOutputLength, file);
104 otEXPECT_ACTION(readLength == aOutputLength, error = OT_ERROR_FAILED);
105
106 exit:
107
108 if (file != NULL)
109 {
110 fclose(file);
111 }
112
113 #else // __SANITIZE_ADDRESS__
114
115 /*
116 * THE IMPLEMENTATION BELOW IS NOT COMPLIANT WITH THE THREAD SPECIFICATION.
117 *
118 * Address Sanitizer triggers test failures when reading random
119 * values from /dev/urandom. The pseudo-random number generator
120 * implementation below is only used to enable continuous
121 * integration checks with Address Sanitizer enabled.
122 */
123 otEXPECT_ACTION(aOutput && aOutputLength, error = OT_ERROR_INVALID_ARGS);
124
125 for (uint16_t length = 0; length < aOutputLength; length++)
126 {
127 aOutput[length] = (uint8_t)randomUint32Get();
128 }
129
130 exit:
131
132 #endif // __SANITIZE_ADDRESS__
133
134 return error;
135 }
136