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/*
* 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 */
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