+/*
+ * 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;
+}
projects / apple / xnu.git / blobdiff