random_adaptor_example.c revision 255075 
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: projects/random_number_generator/share/examples/kld/random_adaptor/random_adaptor_example.c 255075 2013-08-30 17:47:53Z markm $");
30
31#include <sys/param.h>
32#include <sys/kernel.h>
33#include <sys/module.h>
34#include <sys/selinfo.h>
35#include <sys/systm.h>
36
37#include <dev/random/random_adaptors.h>
38#include <dev/random/randomdev.h>
39
40#define RNG_NAME "example"
41
42static int random_example_read(void *, int);
43
44struct random_adaptor random_example = {
45	.ident = "Example RNG",
46	.init = (random_init_func_t *)random_null_func,
47	.deinit = (random_deinit_func_t *)random_null_func,
48	.read = random_example_read,
49	.write = (random_write_func_t *)random_null_func,
50	.reseed = (random_reseed_func_t *)random_null_func,
51	.seeded = 1,
52};
53
54/*
55 * Used under the license provided @ http://xkcd.com/221/
56 * http://creativecommons.org/licenses/by-nc/2.5/
57 */
58static u_char
59getRandomNumber(void)
60{
61	return 4;   /* chosen by fair dice roll, guaranteed to be random */
62}
63
64static int
65random_example_read(void *buf, int c)
66{
67	u_char *b;
68	int count;
69
70	b = buf;
71
72	for (count = 0; count < c; count++) {
73		b[count] = getRandomNumber();
74	}
75
76	printf("returning %d bytes of pure randomness\n", c);
77	return (c);
78}
79
80static int
81random_example_modevent(module_t mod, int type, void *unused)
82{
83
84	switch (type) {
85	case MOD_LOAD:
86		random_adaptor_register(RNG_NAME, &random_example);
87		EVENTHANDLER_INVOKE(random_adaptor_attach, &random_example);
88		return (0);
89	}
90
91	return (EINVAL);
92}
93
94RANDOM_ADAPTOR_MODULE(random_example, random_example_modevent, 1);
95