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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * Generic address resultion entity
3 *
4 * Authors:
5 * net_random Alan Cox
6 * net_ratelimit Andy Kleen
7 *
8 * Created by Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
9 *
10 * This program is free software; you can redistribute it and/or
11 * modify it under the terms of the GNU General Public License
12 * as published by the Free Software Foundation; either version
13 * 2 of the License, or (at your option) any later version.
14 */
15
16#include <linux/module.h>
17#include <linux/jiffies.h>
18#include <linux/kernel.h>
Arnaldo Carvalho de Melo20380732005-08-16 02:18:02 -030019#include <linux/inet.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070020#include <linux/mm.h>
Arnaldo Carvalho de Melo20380732005-08-16 02:18:02 -030021#include <linux/net.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070022#include <linux/string.h>
23#include <linux/types.h>
24#include <linux/random.h>
25#include <linux/percpu.h>
26#include <linux/init.h>
27
Matt Mackall5e43db72005-07-27 15:24:42 -070028#include <asm/byteorder.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070029#include <asm/system.h>
30#include <asm/uaccess.h>
31
Linus Torvalds1da177e2005-04-16 15:20:36 -070032/*
33 This is a maximally equidistributed combined Tausworthe generator
34 based on code from GNU Scientific Library 1.5 (30 Jun 2004)
35
36 x_n = (s1_n ^ s2_n ^ s3_n)
37
38 s1_{n+1} = (((s1_n & 4294967294) <<12) ^ (((s1_n <<13) ^ s1_n) >>19))
39 s2_{n+1} = (((s2_n & 4294967288) << 4) ^ (((s2_n << 2) ^ s2_n) >>25))
40 s3_{n+1} = (((s3_n & 4294967280) <<17) ^ (((s3_n << 3) ^ s3_n) >>11))
41
42 The period of this generator is about 2^88.
43
44 From: P. L'Ecuyer, "Maximally Equidistributed Combined Tausworthe
45 Generators", Mathematics of Computation, 65, 213 (1996), 203--213.
46
47 This is available on the net from L'Ecuyer's home page,
48
49 http://www.iro.umontreal.ca/~lecuyer/myftp/papers/tausme.ps
50 ftp://ftp.iro.umontreal.ca/pub/simulation/lecuyer/papers/tausme.ps
51
52 There is an erratum in the paper "Tables of Maximally
53 Equidistributed Combined LFSR Generators", Mathematics of
54 Computation, 68, 225 (1999), 261--269:
55 http://www.iro.umontreal.ca/~lecuyer/myftp/papers/tausme2.ps
56
57 ... the k_j most significant bits of z_j must be non-
58 zero, for each j. (Note: this restriction also applies to the
59 computer code given in [4], but was mistakenly not mentioned in
60 that paper.)
61
62 This affects the seeding procedure by imposing the requirement
63 s1 > 1, s2 > 7, s3 > 15.
64
65*/
66struct nrnd_state {
67 u32 s1, s2, s3;
68};
69
70static DEFINE_PER_CPU(struct nrnd_state, net_rand_state);
71
72static u32 __net_random(struct nrnd_state *state)
73{
74#define TAUSWORTHE(s,a,b,c,d) ((s&c)<<d) ^ (((s <<a) ^ s)>>b)
75
76 state->s1 = TAUSWORTHE(state->s1, 13, 19, 4294967294UL, 12);
77 state->s2 = TAUSWORTHE(state->s2, 2, 25, 4294967288UL, 4);
78 state->s3 = TAUSWORTHE(state->s3, 3, 11, 4294967280UL, 17);
79
80 return (state->s1 ^ state->s2 ^ state->s3);
81}
82
83static void __net_srandom(struct nrnd_state *state, unsigned long s)
84{
85 if (s == 0)
86 s = 1; /* default seed is 1 */
87
88#define LCG(n) (69069 * n)
89 state->s1 = LCG(s);
90 state->s2 = LCG(state->s1);
91 state->s3 = LCG(state->s2);
92
93 /* "warm it up" */
94 __net_random(state);
95 __net_random(state);
96 __net_random(state);
97 __net_random(state);
98 __net_random(state);
99 __net_random(state);
100}
101
102
103unsigned long net_random(void)
104{
105 unsigned long r;
106 struct nrnd_state *state = &get_cpu_var(net_rand_state);
107 r = __net_random(state);
108 put_cpu_var(state);
109 return r;
110}
111
112
113void net_srandom(unsigned long entropy)
114{
115 struct nrnd_state *state = &get_cpu_var(net_rand_state);
116 __net_srandom(state, state->s1^entropy);
117 put_cpu_var(state);
118}
119
120void __init net_random_init(void)
121{
122 int i;
123
124 for (i = 0; i < NR_CPUS; i++) {
125 struct nrnd_state *state = &per_cpu(net_rand_state,i);
126 __net_srandom(state, i+jiffies);
127 }
128}
129
130static int net_random_reseed(void)
131{
132 int i;
133 unsigned long seed[NR_CPUS];
134
135 get_random_bytes(seed, sizeof(seed));
136 for (i = 0; i < NR_CPUS; i++) {
137 struct nrnd_state *state = &per_cpu(net_rand_state,i);
138 __net_srandom(state, seed[i]);
139 }
140 return 0;
141}
142late_initcall(net_random_reseed);
143
144int net_msg_cost = 5*HZ;
145int net_msg_burst = 10;
146
147/*
148 * All net warning printk()s should be guarded by this function.
149 */
150int net_ratelimit(void)
151{
152 return __printk_ratelimit(net_msg_cost, net_msg_burst);
153}
154
155EXPORT_SYMBOL(net_random);
156EXPORT_SYMBOL(net_ratelimit);
157EXPORT_SYMBOL(net_srandom);
Matt Mackall5e43db72005-07-27 15:24:42 -0700158
159/*
160 * Convert an ASCII string to binary IP.
161 * This is outside of net/ipv4/ because various code that uses IP addresses
162 * is otherwise not dependent on the TCP/IP stack.
163 */
164
165__u32 in_aton(const char *str)
166{
167 unsigned long l;
168 unsigned int val;
169 int i;
170
171 l = 0;
172 for (i = 0; i < 4; i++)
173 {
174 l <<= 8;
175 if (*str != '\0')
176 {
177 val = 0;
178 while (*str != '\0' && *str != '.')
179 {
180 val *= 10;
181 val += *str - '0';
182 str++;
183 }
184 l |= val;
185 if (*str != '\0')
186 str++;
187 }
188 }
189 return(htonl(l));
190}
191
192EXPORT_SYMBOL(in_aton);