1/*-
2 * Copyright (c) 2013 Arthur Mesh <arthurmesh@gmail.com>
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
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer
10 *    in this position and unchanged.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 *
26 */
27
28#include <sys/cdefs.h>
29__FBSDID("$FreeBSD$");
30
31#include <sys/param.h>
32#include <sys/kernel.h>
33#include <sys/lock.h>
34#include <sys/module.h>
35#include <sys/random.h>
36#include <sys/systm.h>
37
38#include <dev/random/live_entropy_sources.h>
39#include <dev/random/random_adaptors.h>
40#include <dev/random/randomdev.h>
41
42static int random_example_read(void *, int);
43
44struct random_adaptor random_example = {
45	.ident = "Example RNG",
46	.source = RANDOM_PURE_BOGUS,	/* Make sure this is in
47					 * sys/random.h and is unique */
48	.read = random_example_read,
49};
50
51/*
52 * Used under the license provided @ http://xkcd.com/221/
53 * http://creativecommons.org/licenses/by-nc/2.5/
54 */
55static uint8_t
56getRandomNumber(void)
57{
58	return 4;   /* chosen by fair dice roll, guaranteed to be random */
59}
60
61static int
62random_example_read(void *buf, int c)
63{
64	uint8_t *b;
65	int count;
66
67	b = buf;
68
69	for (count = 0; count < c; count++)
70		b[count] = getRandomNumber();
71
72	printf("returning %d bytes of pure randomness\n", c);
73	return (c);
74}
75
76static int
77random_example_modevent(module_t mod, int type, void *unused)
78{
79	int error = 0;
80
81	switch (type) {
82	case MOD_LOAD:
83		live_entropy_source_register(&random_example);
84		break;
85
86	case MOD_UNLOAD:
87		live_entropy_source_deregister(&random_example);
88		break;
89
90	case MOD_SHUTDOWN:
91		break;
92
93	default:
94		error = EOPNOTSUPP;
95		break;
96	}
97
98	return (error);
99}
100
101LIVE_ENTROPY_SRC_MODULE(live_entropy_source_example, random_example_modevent, 1);
102