00b67f09dd
Also known as ISC bind. This import adds utilities such as host(1), dig(1), and nslookup(1), as well as many other tools and libraries. Change-Id: I035ca46e64f1965d57019e773f4ff0ef035e4aa3
124 lines
3.1 KiB
C
124 lines
3.1 KiB
C
/* $NetBSD: random.c,v 1.5 2014/12/10 04:37:59 christos Exp $ */
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/*
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* Copyright (C) 2004, 2005, 2007, 2009, 2013, 2014 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/or 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 1.28 2009/07/16 05:52:46 marka Exp */
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/*! \file */
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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((unsigned)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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#elif defined(HAVE_ARC4RANDOM_ADDRANDOM)
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arc4random_addrandom((u_char *) &seed, sizeof(isc_uint32_t));
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#else
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/*
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* If arcrandom() is available and no corresponding seeding
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* function arc4random_addrandom() is available, no seeding is
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* done on such platforms (e.g., OpenBSD 5.5). This is because
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* the OS itself is supposed to seed the RNG and it is assumed
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* that no explicit seeding is required.
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*/
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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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#if RAND_MAX >= 0xfffff
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/* We have at least 20 bits. Use lower 16 excluding lower most 4 */
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*val = ((rand() >> 4) & 0xffff) | ((rand() << 12) & 0xffff0000);
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#elif RAND_MAX >= 0x7fff
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/* We have at least 15 bits. Use lower 10/11 excluding lower most 4 */
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*val = ((rand() >> 4) & 0x000007ff) | ((rand() << 7) & 0x003ff800) |
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((rand() << 18) & 0xffc00000);
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#else
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#error RAND_MAX is too small
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#endif
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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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isc_uint32_t rnd;
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REQUIRE(jitter < max || (jitter == 0 && max == 0));
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if (jitter == 0)
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return (max);
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isc_random_get(&rnd);
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return (max - rnd % jitter);
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}
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