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 42 static int random_example_read(void *, int); 43 44 struct 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 */ 55 static uint8_t 56 getRandomNumber(void) 57 { 58 return 4; /* chosen by fair dice roll, guaranteed to be random */ 59 } 60 61 static int 62 random_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 76 static int 77 random_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 } 100 101 LIVE_ENTROPY_SRC_MODULE(live_entropy_source_example, random_example_modevent, 1); 102