/* * Copyright (c) 2009 Apple Inc. All rights reserved. * * @APPLE_OSREFERENCE_LICENSE_HEADER_START@ * * This file contains Original Code and/or Modifications of Original Code * as defined in and that are subject to the Apple Public Source License * Version 2.0 (the 'License'). You may not use this file except in * compliance with the License. The rights granted to you under the License * may not be used to create, or enable the creation or redistribution of, * unlawful or unlicensed copies of an Apple operating system, or to * circumvent, violate, or enable the circumvention or violation of, any * terms of an Apple operating system software license agreement. * * Please obtain a copy of the License at * http://www.opensource.apple.com/apsl/ and read it before using this file. * * The Original Code and all software distributed under the License are * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT. * Please see the License for the specific language governing rights and * limitations under the License. * * @APPLE_OSREFERENCE_LICENSE_HEADER_END@ */ /*- * Copyright (C) 2003 WIDE Project. * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Neither the name of the project nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * $KAME: ip6_id.c,v 1.13 2003/09/16 09:11:19 itojun Exp $ */ /*- * Copyright 1998 Niels Provos <provos@citi.umich.edu> * All rights reserved. * * Theo de Raadt <deraadt@openbsd.org> came up with the idea of using * such a mathematical system to generate more random (yet non-repeating) * ids to solve the resolver/named problem. But Niels designed the * actual system based on the constraints. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by Niels Provos. * 4. The name of the author may not be used to endorse or promote products * derived from this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. * * $OpenBSD: ip_id.c,v 1.6 2002/03/15 18:19:52 millert Exp $ */ #include <sys/cdefs.h> /* * seed = random (bits - 1) bit * n = prime, g0 = generator to n, * j = random so that gcd(j,n-1) == 1 * g = g0^j mod n will be a generator again. * * X[0] = random seed. * X[n] = a*X[n-1]+b mod m is a Linear Congruential Generator * with a = 7^(even random) mod m, * b = random with gcd(b,m) == 1 * m = constant and a maximal period of m-1. * * The transaction id is determined by: * id[n] = seed xor (g^X[n] mod n) * * Effectivly the id is restricted to the lower (bits - 1) bits, thus * yielding two different cycles by toggling the msb on and off. * This avoids reuse issues caused by reseeding. */ #include <sys/types.h> #include <sys/socket.h> #include <sys/param.h> #include <sys/time.h> #include <sys/kernel.h> #include <sys/random.h> #include <libkern/libkern.h> #include <net/if.h> #include <net/route.h> #include <netinet/in.h> #include <netinet/ip6.h> #include <netinet6/ip6_var.h> #ifndef INT32_MAX #define INT32_MAX 0x7fffffffU #endif struct randomtab { const int ru_bits; /* resulting bits */ const long ru_out; /* Time after wich will be reseeded */ const u_int32_t ru_max; /* Uniq cycle, avoid blackjack prediction */ const u_int32_t ru_gen; /* Starting generator */ const u_int32_t ru_n; /* ru_n: prime, ru_n - 1: product of pfacts[] */ const u_int32_t ru_agen; /* determine ru_a as ru_agen^(2*rand) */ const u_int32_t ru_m; /* ru_m = 2^x*3^y */ const u_int32_t pfacts[4]; /* factors of ru_n */ u_int32_t ru_counter; u_int32_t ru_msb; u_int32_t ru_x; u_int32_t ru_seed, ru_seed2; u_int32_t ru_a, ru_b; u_int32_t ru_g; long ru_reseed; }; static struct randomtab randomtab_32 = { 32, /* resulting bits */ 180, /* Time after wich will be reseeded */ 1000000000, /* Uniq cycle, avoid blackjack prediction */ 2, /* Starting generator */ 2147483629, /* RU_N-1 = 2^2*3^2*59652323 */ 7, /* determine ru_a as RU_AGEN^(2*rand) */ 1836660096, /* RU_M = 2^7*3^15 - don't change */ { 2, 3, 59652323, 0 }, /* factors of ru_n */ 0, 0, 0, 0, 0, 0, 0, 0, 0 }; static struct randomtab randomtab_20 = { 20, /* resulting bits */ 180, /* Time after wich will be reseeded */ 200000, /* Uniq cycle, avoid blackjack prediction */ 2, /* Starting generator */ 524269, /* RU_N-1 = 2^2*3^2*14563 */ 7, /* determine ru_a as RU_AGEN^(2*rand) */ 279936, /* RU_M = 2^7*3^7 - don't change */ { 2, 3, 14563, 0 }, /* factors of ru_n */ 0, 0, 0, 0, 0, 0, 0, 0, 0 }; static u_int32_t pmod(u_int32_t, u_int32_t, u_int32_t); static void initid(struct randomtab *); static u_int32_t randomid(struct randomtab *); /* * Do a fast modular exponation, returned value will be in the range * of 0 - (mod-1) */ static u_int32_t pmod(u_int32_t gen, u_int32_t expo, u_int32_t mod) { u_int64_t s, t, u; s = 1; t = gen; u = expo; while (u) { if (u & 1) s = (s * t) % mod; u >>= 1; t = (t * t) % mod; } return (s); } /* * Initalizes the seed and chooses a suitable generator. Also toggles * the msb flag. The msb flag is used to generate two distinct * cycles of random numbers and thus avoiding reuse of ids. * * This function is called from id_randomid() when needed, an * application does not have to worry about it. */ static void initid(struct randomtab *p) { u_int32_t j, i; int noprime = 1; struct timeval timenow; getmicrotime(&timenow); p->ru_x = random() % p->ru_m; /* (bits - 1) bits of random seed */ p->ru_seed = random() & (~0U >> (32 - p->ru_bits + 1)); p->ru_seed2 = random() & (~0U >> (32 - p->ru_bits + 1)); /* Determine the LCG we use */ p->ru_b = (random() & (~0U >> (32 - p->ru_bits))) | 1; p->ru_a = pmod(p->ru_agen, (random() & (~0U >> (32 - p->ru_bits))) & (~1U), p->ru_m); while (p->ru_b % 3 == 0) p->ru_b += 2; j = random() % p->ru_n; /* * Do a fast gcd(j, RU_N - 1), so we can find a j with * gcd(j, RU_N - 1) == 1, giving a new generator for * RU_GEN^j mod RU_N */ while (noprime) { for (i = 0; p->pfacts[i] > 0; i++) if (j % p->pfacts[i] == 0) break; if (p->pfacts[i] == 0) noprime = 0; else j = (j + 1) % p->ru_n; } p->ru_g = pmod(p->ru_gen, j, p->ru_n); p->ru_counter = 0; p->ru_reseed = timenow.tv_sec + p->ru_out; p->ru_msb = p->ru_msb ? 0 : (1U << (p->ru_bits - 1)); } static u_int32_t randomid(struct randomtab *p) { int i, n; u_int32_t tmp; struct timeval timenow; getmicrotime(&timenow); if (p->ru_counter >= p->ru_max || timenow.tv_sec > p->ru_reseed) initid(p); tmp = random(); /* Skip a random number of ids */ n = tmp & 0x3; tmp = tmp >> 2; if (p->ru_counter + n >= p->ru_max) initid(p); for (i = 0; i <= n; i++) { /* Linear Congruential Generator */ p->ru_x = (u_int32_t)((u_int64_t)p->ru_a * p->ru_x + p->ru_b) % p->ru_m; } p->ru_counter += i; return (p->ru_seed ^ pmod(p->ru_g, p->ru_seed2 ^ p->ru_x, p->ru_n)) | p->ru_msb; } u_int32_t ip6_randomid(void) { return randomid(&randomtab_32); } u_int32_t ip6_randomflowlabel(void) { return randomid(&randomtab_20) & 0xfffff; }