xref: /openbmc/linux/net/core/utils.c (revision d5cb9783536a41df9f9cba5b0a1d78047ed787f7)
1 /*
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>
19 #include <linux/inet.h>
20 #include <linux/mm.h>
21 #include <linux/net.h>
22 #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 
28 #include <asm/byteorder.h>
29 #include <asm/system.h>
30 #include <asm/uaccess.h>
31 
32 /*
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 */
66 struct nrnd_state {
67 	u32 s1, s2, s3;
68 };
69 
70 static DEFINE_PER_CPU(struct nrnd_state, net_rand_state);
71 
72 static 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 
83 static 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 
103 unsigned 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 
113 void 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 
120 void __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 
130 static 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 }
142 late_initcall(net_random_reseed);
143 
144 int net_msg_cost = 5*HZ;
145 int net_msg_burst = 10;
146 
147 /*
148  * All net warning printk()s should be guarded by this function.
149  */
150 int net_ratelimit(void)
151 {
152 	return __printk_ratelimit(net_msg_cost, net_msg_burst);
153 }
154 
155 EXPORT_SYMBOL(net_random);
156 EXPORT_SYMBOL(net_ratelimit);
157 EXPORT_SYMBOL(net_srandom);
158 
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 
192 EXPORT_SYMBOL(in_aton);
193