summaryrefslogtreecommitdiffstats
path: root/tests/prng.c
blob: 8d78ea523b9ea09f412bd16f4990dada278f377b (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
/*
 * Very simple prng to allow for randomized tests with reproducable
 * results.
 *
 * Copyright (C) 2012 by Open Source Routing.
 * Copyright (C) 2012 by Internet Systems Consortium, Inc. ("ISC")
 *
 * This file is part of Quagga
 *
 * Quagga is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the
 * Free Software Foundation; either version 2, or (at your option) any
 * later version.
 *
 * Quagga is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Quagga; see the file COPYING.  If not, write to the Free
 * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
 * 02111-1307, USA.
 */

#include <assert.h>
#include <stdlib.h>
#include <string.h>

#include "prng.h"

struct prng
{
  unsigned long long state1;
  unsigned long long state2;
};

static char
prng_bit(struct prng *prng)
{
  prng->state1 *= 2416;
  prng->state1 += 374441;
  prng->state1 %= 1771875;

  if (prng->state1 % 2)
    {
      prng->state2 *= 84589;
      prng->state2 += 45989;
      prng->state2 %= 217728;
    }

  return prng->state2 % 2;
}

struct prng*
prng_new(unsigned long long seed)
{
  struct prng *rv = calloc(sizeof(*rv), 1);
  assert(rv);

  rv->state1 = rv->state2 = seed;

  return rv;
}

unsigned int
prng_rand(struct prng *prng)
{
  unsigned int i, rv = 0;

  for (i = 0; i < 32; i++)
    {
      rv |= prng_bit(prng);
      rv <<= 1;
    }
  return rv;
}

const char *
prng_fuzz(struct prng *prng,
          const char *string,
          const char *charset,
          unsigned int operations)
{
  static char buf[256];
  unsigned int charset_len;
  unsigned int i;
  unsigned int offset;
  unsigned int op;
  unsigned int character;

  assert(strlen(string) < sizeof(buf));

  strncpy(buf, string, sizeof(buf));
  charset_len = strlen(charset);

  for (i = 0; i < operations; i++)
    {
      offset = prng_rand(prng) % strlen(buf);
      op = prng_rand(prng) % 3;

      switch (op)
        {
        case 0:
          /* replace */
          character = prng_rand(prng) % charset_len;
          buf[offset] = charset[character];
          break;
        case 1:
          /* remove */
          memmove(buf + offset, buf + offset + 1, strlen(buf) - offset);
          break;
        case 2:
          /* insert */
          assert(strlen(buf) + 1 < sizeof(buf));

          memmove(buf + offset + 1, buf + offset, strlen(buf) + 1 - offset);
          character = prng_rand(prng) % charset_len;
          buf[offset] = charset[character];
          break;
        }
    }
  return buf;
}

void
prng_free(struct prng *prng)
{
  free(prng);
}