1 /*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21
22 /*
23 * Copyright 2009 Sun Microsystems, Inc. All rights reserved.
24 * Use is subject to license terms.
25 */
26
27 /* Copyright (c) 1988 AT&T */
28 /* All Rights Reserved */
29
30 /*
31 * drand48, etc. pseudo-random number generator
32 * This implementation assumes unsigned short integers of at least
33 * 16 bits, long integers of at least 32 bits, and ignores
34 * overflows on adding or multiplying two unsigned integers.
35 * Two's-complement representation is assumed in a few places.
36 * Some extra masking is done if unsigneds are exactly 16 bits
37 * or longs are exactly 32 bits, but so what?
38 * An assembly-language implementation would run significantly faster.
39 */
40 /*
41 * New assumptions (supercede those stated above) for 64-bit work.
42 * Longs are now 64 bits, and we are bound by standards to return
43 * type long, hovever all internal calculations where long was
44 * previously used (32 bit precision) are now using the int32_t
45 * type (32 bit precision in both ILP32 and LP64 worlds).
46 */
47
48 #include <sys/mutex.h>
49
50 static kmutex_t seed_lock;
51 static int init48done = 0;
52
53 #define EXPORT0(TYPE, fn, fnu) TYPE fn() { \
54 TYPE res; \
55 mutex_enter(&seed_lock); \
56 res = fnu(); \
57 mutex_exit(&seed_lock); \
58 return (res); }
59 #define EXPORT1(TYPE, fn, fnu) TYPE fn(unsigned short xsubi[3]) { \
60 TYPE res; \
61 mutex_enter(&seed_lock); \
62 res = fnu(xsubi); \
63 mutex_exit(&seed_lock); \
64 return (res); }
65
66 #define N 16
67 #define MASK ((unsigned)(1 << (N - 1)) + (1 << (N - 1)) - 1)
68 #define LOW(x) ((unsigned)(x) & MASK)
69 #define HIGH(x) LOW((x) >> N)
70 #define MUL(x, y, z) { int32_t l = (int32_t)(x) * (int32_t)(y); \
71 (z)[0] = LOW(l); (z)[1] = HIGH(l); }
72 #define CARRY(x, y) ((int32_t)(x) + (int32_t)(y) > MASK)
73 #define ADDEQU(x, y, z) (z = CARRY(x, (y)), x = LOW(x + (y)))
74 #define X0 0x330E
75 #define X1 0xABCD
76 #define X2 0x1234
77 #define A0 0xE66D
78 #define A1 0xDEEC
79 #define A2 0x5
80 #define C 0xB
81 #define SET3(x, x0, x1, x2) ((x)[0] = (x0), (x)[1] = (x1), (x)[2] = (x2))
82 #define SETLOW(x, y, n) SET3(x, LOW((y)[n]), LOW((y)[(n)+1]), LOW((y)[(n)+2]))
83 #define SEED(x0, x1, x2) (SET3(x, x0, x1, x2), SET3(a, A0, A1, A2), c = C)
84 #define REST(v) for (i = 0; i < 3; i++) { xsubi[i] = x[i]; x[i] = temp[i]; } \
85 return (v)
86 #define NEST(TYPE, f, F) static TYPE f(unsigned short *xsubi) { \
87 int i; TYPE v; unsigned temp[3]; \
88 for (i = 0; i < 3; i++) { temp[i] = x[i]; x[i] = LOW(xsubi[i]); } \
89 v = F(); REST(v); }
90
91 /* Way ugly solution to problem names, but it works */
92 #define x _drand48_x
93 #define a _drand48_a
94 #define c _drand48_c
95 /* End way ugly */
96 static unsigned x[3] = { X0, X1, X2 }, a[3] = { A0, A1, A2 }, c = C;
97 static unsigned short lastx[3];
98 static void next(void);
99
100 static long
ipf_r_lrand48_u(void)101 ipf_r_lrand48_u(void)
102 {
103 next();
104 return ((long)((int32_t)x[2] << (N - 1)) + (x[1] >> 1));
105 }
106
107 static void
init48(void)108 init48(void)
109 {
110 mutex_init(&seed_lock, 0L, MUTEX_DRIVER, 0L);
111 init48done = 1;
112 }
113
114 static long
ipf_r_mrand48_u(void)115 ipf_r_mrand48_u(void)
116 {
117 next();
118 return ((long)((int32_t)x[2] << N) + x[1]);
119 }
120
121 static void
next(void)122 next(void)
123 {
124 unsigned p[2], q[2], r[2], carry0, carry1;
125
126 MUL(a[0], x[0], p);
127 ADDEQU(p[0], c, carry0);
128 ADDEQU(p[1], carry0, carry1);
129 MUL(a[0], x[1], q);
130 ADDEQU(p[1], q[0], carry0);
131 MUL(a[1], x[0], r);
132 x[2] = LOW(carry0 + carry1 + CARRY(p[1], r[0]) + q[1] + r[1] +
133 a[0] * x[2] + a[1] * x[1] + a[2] * x[0]);
134 x[1] = LOW(p[1] + r[0]);
135 x[0] = LOW(p[0]);
136 }
137
138 void
ipf_r_srand48(long seedval)139 ipf_r_srand48(long seedval)
140 {
141 int32_t fixseed = (int32_t)seedval; /* limit to 32 bits */
142
143 if (init48done == 0)
144 init48();
145 mutex_enter(&seed_lock);
146 SEED(X0, LOW(fixseed), HIGH(fixseed));
147 mutex_exit(&seed_lock);
148 }
149
EXPORT0(long,ipf_r_lrand48,ipf_r_lrand48_u)150 EXPORT0(long, ipf_r_lrand48, ipf_r_lrand48_u)
151
152 #include <sys/random.h>
153
154 unsigned
155 ipf_random()
156 {
157 static int seeded = 0;
158
159 if (seeded == 0) {
160 long seed;
161
162 /*
163 * Keep reseeding until some good randomness comes from the
164 * kernel. One of two things will happen: it will succeed or
165 * it will fail (with poor randomness), thus creating NAT
166 * sessions will be "slow" until enough randomness is gained
167 * to not need to get more. It isn't necessary to initialise
168 * seed as it will just pickup whatever random garbage has
169 * been left on the heap and that's good enough until we
170 * get some good garbage.
171 */
172 if (random_get_bytes((uint8_t *)&seed, sizeof (seed)) == 0)
173 seeded = 1;
174 ipf_r_srand48(seed);
175 }
176
177 return (unsigned)ipf_r_lrand48();
178 }
179