1 /* 2 * util/random.h - thread safe random generator, which is reasonably secure. 3 * 4 * Copyright (c) 2007, NLnet Labs. All rights reserved. 5 * 6 * This software is open source. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 12 * Redistributions of source code must retain the above copyright notice, 13 * this list of conditions and the following disclaimer. 14 * 15 * Redistributions in binary form must reproduce the above copyright notice, 16 * this list of conditions and the following disclaimer in the documentation 17 * and/or other materials provided with the distribution. 18 * 19 * Neither the name of the NLNET LABS nor the names of its contributors may 20 * be used to endorse or promote products derived from this software without 21 * specific prior written permission. 22 * 23 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 24 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 25 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 26 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 27 * HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 28 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED 29 * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR 30 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF 31 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING 32 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS 33 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 34 */ 35 36 #ifndef UTIL_RANDOM_H 37 #define UTIL_RANDOM_H 38 39 /** 40 * \file 41 * Thread safe random functions. Similar to arc4random() with an explicit 42 * initialisation routine. 43 */ 44 45 /** 46 * random state structure. 47 */ 48 struct ub_randstate; 49 50 /** 51 * Initialize the system randomness. Obtains entropy from the system 52 * before a chroot or privilege makes it unavailable. 53 * You do not have to call this, otherwise ub_initstate does so. 54 * @param seed: seed value to create state (if no good entropy is found). 55 */ 56 void ub_systemseed(unsigned int seed); 57 58 /** 59 * Initialize a random generator state for use 60 * @param seed: seed value to create state contents. 61 * (ignored for arc4random). 62 * @param from: if not NULL, the seed is taken from this random structure. 63 * can be used to seed random states via a parent-random-state that 64 * is itself seeded with entropy. 65 * @return new state or NULL alloc failure. 66 */ 67 struct ub_randstate* ub_initstate(unsigned int seed, 68 struct ub_randstate* from); 69 70 /** 71 * Generate next random number from the state passed along. 72 * Thread safe, so random numbers are repeatable. 73 * @param state: must have been initialised with ub_initstate. 74 * @return: random 31 bit value. 75 */ 76 long int ub_random(struct ub_randstate* state); 77 78 /** 79 * Generate random number between 0 and x-1. No modulo bias. 80 * @param state: must have been initialised with ub_initstate. 81 * @param x: an upper limit. not (negative or zero). must be smaller than 2**31. 82 * @return: random value between 0..x-1. Possibly more than one 83 * random number is picked from the random stream to satisfy this. 84 */ 85 long int ub_random_max(struct ub_randstate* state, long int x); 86 87 /** 88 * Delete the random state. 89 * @param state: to delete. 90 */ 91 void ub_randfree(struct ub_randstate* state); 92 93 #endif /* UTIL_RANDOM_H */ 94