103 lines
2.3 KiB
C
103 lines
2.3 KiB
C
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/*
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* Copyright (C) 2004 Internet Systems Consortium, Inc. ("ISC")
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* Copyright (C) 1999-2003 Internet Software Consortium.
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
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* REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
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* AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
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* INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
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* LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
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* OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
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* PERFORMANCE OF THIS SOFTWARE.
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*/
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/* $Id: random.c,v 1.15.74.5 2004/03/08 09:04:49 marka Exp $ */
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#include <config.h>
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#include <stdlib.h>
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#include <time.h> /* Required for time(). */
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#ifdef HAVE_SYS_TYPES_H
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#include <sys/types.h>
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#endif
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#ifdef HAVE_UNISTD_H
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#include <unistd.h>
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#endif
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#include <isc/mutex.h>
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#include <isc/once.h>
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#include <isc/random.h>
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#include <isc/string.h>
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#include <isc/util.h>
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static isc_once_t once = ISC_ONCE_INIT;
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static void
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initialize_rand(void)
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{
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#ifndef HAVE_ARC4RANDOM
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unsigned int pid = getpid();
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/*
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* The low bits of pid generally change faster.
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* Xor them with the high bits of time which change slowly.
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*/
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pid = ((pid << 16) & 0xffff0000) | ((pid >> 16) & 0xffff);
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srand(time(NULL) ^ pid);
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#endif
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}
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static void
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initialize(void)
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{
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RUNTIME_CHECK(isc_once_do(&once, initialize_rand) == ISC_R_SUCCESS);
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}
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void
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isc_random_seed(isc_uint32_t seed)
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{
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initialize();
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#ifndef HAVE_ARC4RANDOM
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srand(seed);
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#else
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arc4random_addrandom((u_char *) &seed, sizeof(isc_uint32_t));
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#endif
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}
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void
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isc_random_get(isc_uint32_t *val)
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{
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REQUIRE(val != NULL);
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initialize();
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#ifndef HAVE_ARC4RANDOM
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/*
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* rand()'s lower bits are not random.
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* rand()'s upper bit is zero.
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*/
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*val = ((rand() >> 4) & 0xffff) | ((rand() << 12) & 0xffff0000);
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#else
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*val = arc4random();
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#endif
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}
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isc_uint32_t
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isc_random_jitter(isc_uint32_t max, isc_uint32_t jitter) {
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REQUIRE(jitter < max);
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if (jitter == 0)
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return (max);
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else
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#ifndef HAVE_ARC4RANDOM
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return (max - rand() % jitter);
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#else
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return (max - arc4random() % jitter);
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#endif
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}
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