random_adaptor_example.c revision 256381 
133965Sjdp/*-
2218822Sdim * Copyright (c) 2013 Arthur Mesh <arthurmesh@gmail.com>
3218822Sdim * All rights reserved.
433965Sjdp *
533965Sjdp * Redistribution and use in source and binary forms, with or without
633965Sjdp * modification, are permitted provided that the following conditions
733965Sjdp * are met:
833965Sjdp * 1. Redistributions of source code must retain the above copyright
933965Sjdp *    notice, this list of conditions and the following disclaimer
1033965Sjdp *    in this position and unchanged.
1133965Sjdp * 2. Redistributions in binary form must reproduce the above copyright
1233965Sjdp *    notice, this list of conditions and the following disclaimer in the
1333965Sjdp *    documentation and/or other materials provided with the distribution.
1433965Sjdp *
1533965Sjdp * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
1633965Sjdp * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
1733965Sjdp * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
1833965Sjdp * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19218822Sdim * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20218822Sdim * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
2133965Sjdp * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
2233965Sjdp * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
2333965Sjdp * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
2433965Sjdp * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
2533965Sjdp *
2633965Sjdp */
2733965Sjdp
2833965Sjdp#include <sys/cdefs.h>
2933965Sjdp__FBSDID("$FreeBSD: stable/10/share/examples/kld/random_adaptor/random_adaptor_example.c 256381 2013-10-12 15:31:36Z markm $");
3033965Sjdp
3138889Sjdp#include <sys/param.h>
3233965Sjdp#include <sys/kernel.h>
3338889Sjdp#include <sys/lock.h>
3433965Sjdp#include <sys/module.h>
3533965Sjdp#include <sys/random.h>
3638889Sjdp#include <sys/systm.h>
3733965Sjdp
3833965Sjdp#include <dev/random/live_entropy_sources.h>
3933965Sjdp#include <dev/random/random_adaptors.h>
4060484Sobrien#include <dev/random/randomdev.h>
4133965Sjdp
4233965Sjdpstatic int random_example_read(void *, int);
4333965Sjdp
44130561Sobrienstruct random_adaptor random_example = {
45130561Sobrien	.ident = "Example RNG",
46130561Sobrien	.source = RANDOM_PURE_BOGUS,	/* Make sure this is in
47130561Sobrien					 * sys/random.h and is unique */
48130561Sobrien	.read = random_example_read,
49130561Sobrien};
50130561Sobrien
51130561Sobrien/*
52130561Sobrien * Used under the license provided @ http://xkcd.com/221/
53130561Sobrien * http://creativecommons.org/licenses/by-nc/2.5/
54130561Sobrien */
55130561Sobrienstatic uint8_t
56130561SobriengetRandomNumber(void)
57130561Sobrien{
58130561Sobrien	return 4;   /* chosen by fair dice roll, guaranteed to be random */
5933965Sjdp}
6038889Sjdp
6138889Sjdpstatic int
6238889Sjdprandom_example_read(void *buf, int c)
6338889Sjdp{
6438889Sjdp	uint8_t *b;
6533965Sjdp	int count;
6633965Sjdp
6733965Sjdp	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