contrib/bind-9.5.2/lib/isc/include/isc/random.h

   1 /*
   2  * Copyright (C) 2004-2007, 2009  Internet Systems Consortium, Inc. ("ISC")
   3  * Copyright (C) 1999-2001  Internet Software Consortium.
   4  *
   5  * Permission to use, copy, modify, and/or distribute this software for any
   6  * purpose with or without fee is hereby granted, provided that the above
   7  * copyright notice and this permission notice appear in all copies.
   8  *
   9  * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
  10  * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
  11  * AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
  12  * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
  13  * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
  14  * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
  15  * PERFORMANCE OF THIS SOFTWARE.
  16  */
  17
  18 /* $Id: random.h,v 1.18.128.2 2009/01/19 23:47:03 tbox Exp $ */
  19
  20 #ifndef ISC_RANDOM_H
  21 #define ISC_RANDOM_H 1
  22
  23 #include <isc/lang.h>
  24 #include <isc/types.h>
  25
  26 /*! \file isc/random.h
  27  * \brief Implements a random state pool which will let the caller return a
  28  * series of possibly non-reproducible random values.
  29  *
  30  * Note that the
  31  * strength of these numbers is not all that high, and should not be
  32  * used in cryptography functions.  It is useful for jittering values
  33  * a bit here and there, such as timeouts, etc.
  34  */
  35
  36 ISC_LANG_BEGINDECLS
  37
  38 void
  39 isc_random_seed(isc_uint32_t seed);
  40 /*%<
  41  * Set the initial seed of the random state.
  42  */
  43
  44 void
  45 isc_random_get(isc_uint32_t *val);
  46 /*%<
  47  * Get a random value.
  48  *
  49  * Requires:
  50  *      val != NULL.
  51  */
  52
  53 isc_uint32_t
  54 isc_random_jitter(isc_uint32_t max, isc_uint32_t jitter);
  55 /*%<
  56  * Get a random value between (max - jitter) and (max).
  57  * This is useful for jittering timer values.
  58  */
  59
  60 ISC_LANG_ENDDECLS
  61
  62 #endif /* ISC_RANDOM_H */