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93 lines
3.4 KiB
C
93 lines
3.4 KiB
C
/*
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* util/random.h - thread safe random generator, which is reasonably secure.
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*
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* Copyright (c) 2007, NLnet Labs. All rights reserved.
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*
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* This software is open source.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* Redistributions of source code must retain the above copyright notice,
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* this list of conditions and the following disclaimer.
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*
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* Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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*
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* Neither the name of the NLNET LABS nor the names of its contributors may
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* be used to endorse or promote products derived from this software without
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* specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
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* TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifndef UTIL_RANDOM_H
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#define UTIL_RANDOM_H
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/**
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* \file
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* Thread safe random functions. Similar to arc4random() with an explicit
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* initialisation routine.
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*/
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/**
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* random state structure.
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*/
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struct ub_randstate;
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/**
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* Initialize the system randomness. Obtains entropy from the system
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* before a chroot or privilege makes it unavailable.
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* You do not have to call this, otherwise ub_initstate does so.
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* @param seed: seed value to create state (if no good entropy is found).
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*/
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void ub_systemseed(unsigned int seed);
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/**
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* Initialize a random generator state for use
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* @param seed: seed value to create state contents.
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* (ignored for arc4random).
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* @param from: if not NULL, the seed is taken from this random structure.
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* can be used to seed random states via a parent-random-state that
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* is itself seeded with entropy.
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* @return new state or NULL alloc failure.
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*/
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struct ub_randstate* ub_initstate(unsigned int seed,
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struct ub_randstate* from);
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/**
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* Generate next random number from the state passed along.
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* Thread safe, so random numbers are repeatable.
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* @param state: must have been initialised with ub_initstate.
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* @return: random 31 bit value.
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*/
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long int ub_random(struct ub_randstate* state);
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/**
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* Generate random number between 0 and x-1. No modulo bias.
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* @param state: must have been initialised with ub_initstate.
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* @param x: an upper limit. not (negative or zero). must be smaller than 2**31.
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* @return: random value between 0..x-1. Possibly more than one
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* random number is picked from the random stream to satisfy this.
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*/
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long int ub_random_max(struct ub_randstate* state, long int x);
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/**
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* Delete the random state.
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* @param state: to delete.
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*/
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void ub_randfree(struct ub_randstate* state);
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#endif /* UTIL_RANDOM_H */
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