/* * Copyright (C) Internet Systems Consortium, Inc. ("ISC") * * This Source Code Form is subject to the terms of the Mozilla Public * License, v. 2.0. If a copy of the MPL was not distributed with this * file, You can obtain one at http://mozilla.org/MPL/2.0/. * * See the COPYRIGHT file distributed with this work for additional * information regarding copyright ownership. */ /* $Id: random.h,v 1.20 2009/01/17 23:47:43 tbox Exp $ */ #ifndef ISC_RANDOM_H #define ISC_RANDOM_H 1 #include <isc/lang.h> #include <isc/types.h> #include <isc/entropy.h> #include <isc/mem.h> #include <isc/mutex.h> /*! \file isc/random.h * \brief Implements a random state pool which will let the caller return a * series of possibly non-reproducible random values. * * Note that the * strength of these numbers is not all that high, and should not be * used in cryptography functions. It is useful for jittering values * a bit here and there, such as timeouts, etc. */ ISC_LANG_BEGINDECLS typedef struct isc_rng isc_rng_t; /*%< * Opaque type */ void isc_random_seed(isc_uint32_t seed); /*%< * Set the initial seed of the random state. */ void isc_random_get(isc_uint32_t *val); /*%< * Get a random value. * * Requires: * val != NULL. */ isc_uint32_t isc_random_jitter(isc_uint32_t max, isc_uint32_t jitter); /*%< * Get a random value between (max - jitter) and (max). * This is useful for jittering timer values. */ isc_result_t isc_rng_create(isc_mem_t *mctx, isc_entropy_t *entropy, isc_rng_t **rngp); /*%< * Creates and initializes a pseudo random number generator. The * returned RNG can be used to generate pseudo random numbers. * * The reference count of the returned RNG is set to 1. * * Requires: * \li mctx is a pointer to a valid memory context. * \li entropy is an optional entopy source (can be NULL) * \li rngp != NULL && *rngp == NULL is where a pointer to the RNG is * returned. * * Ensures: *\li If result is ISC_R_SUCCESS: * *rngp points to a valid RNG. * *\li If result is failure: * *rngp does not point to a valid RNG. * * Returns: *\li #ISC_R_SUCCESS Success *\li #ISC_R_NOMEMORY Resource limit: Out of Memory */ void isc_rng_attach(isc_rng_t *source, isc_rng_t **targetp); /*%< * Increments a reference count on the passed RNG. * * Requires: * \li source the RNG struct to attach to (is refcount is incremented) * \li targetp != NULL && *targetp == NULL where a pointer to the * reference incremented RNG is returned. */ void isc_rng_detach(isc_rng_t **rngp); /*%< * Decrements a reference count on the passed RNG. If the reference * count reaches 0, the RNG is destroyed. * * Requires: * \li rngp != NULL the RNG struct to decrement reference for */ isc_uint16_t isc_rng_random(isc_rng_t *rngctx); /*%< * Returns a pseudo random 16-bit unsigned integer. */ isc_uint16_t isc_rng_uniformrandom(isc_rng_t *rngctx, isc_uint16_t upper_bound); /*%< * Returns a uniformly distributed pseudo random 16-bit unsigned * integer. */ ISC_LANG_ENDDECLS #endif /* ISC_RANDOM_H */

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