[apple/network_cmds.git] / unbound / util / random.h

/*
 * util/random.h - thread safe random generator, which is reasonably secure.
 * 
 * Copyright (c) 2007, NLnet Labs. All rights reserved.
 * 
 * This software is open source.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 
 * Redistributions of source code must retain the above copyright notice,
 * this list of conditions and the following disclaimer.
 * 
 * Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 * 
 * Neither the name of the NLNET LABS nor the names of its contributors may
 * be used to endorse or promote products derived from this software without
 * specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
 * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef UTIL_RANDOM_H
#define UTIL_RANDOM_H

/**
 * \file
 * Thread safe random functions. Similar to arc4random() with an explicit
 * initialisation routine.
 */

/**
 * random state structure.
 */
struct ub_randstate;

/**
 * Initialize the system randomness.  Obtains entropy from the system
 * before a chroot or privilege makes it unavailable. 
 * You do not have to call this, otherwise ub_initstate does so.
 * @param seed: seed value to create state (if no good entropy is found).
 */
void ub_systemseed(unsigned int seed);

/**
 * Initialize a random generator state for use 
 * @param seed: seed value to create state contents.
 *	(ignored for arc4random).
 * @param from: if not NULL, the seed is taken from this random structure.
 * 	can be used to seed random states via a parent-random-state that
 * 	is itself seeded with entropy.
 * @return new state or NULL alloc failure.
 */
struct ub_randstate* ub_initstate(unsigned int seed, 
	struct ub_randstate* from);

/**
 * Generate next random number from the state passed along.
 * Thread safe, so random numbers are repeatable.
 * @param state: must have been initialised with ub_initstate.
 * @return: random 31 bit value.
 */
long int ub_random(struct ub_randstate* state);

/**
 * Generate random number between 0 and x-1.  No modulo bias.
 * @param state: must have been initialised with ub_initstate.
 * @param x: an upper limit. not (negative or zero). must be smaller than 2**31.
 * @return: random value between 0..x-1. Possibly more than one
 * random number is picked from the random stream to satisfy this.
 */
long int ub_random_max(struct ub_randstate* state, long int x);

/**
 * Delete the random state.
 * @param state: to delete.
 */
void ub_randfree(struct ub_randstate* state);

#endif /* UTIL_RANDOM_H */
Commit	Line	Data
89c4ed63 A	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 */