1 #include "random_data.h"
2 #include <string.h>
3 #include <malloc_wrappers.h>
4 #include <pb_encode.h>
5
6 #ifndef LLVMFUZZER
7
8 static uint32_t g_random_seed = 1234;
9
random_set_seed(uint32_t seed)10 void random_set_seed(uint32_t seed)
11 {
12 g_random_seed = seed;
13 }
14
random_get_seed()15 uint32_t random_get_seed()
16 {
17 return g_random_seed;
18 }
19
20 /* Uses xorshift64 here instead of rand() for both speed and
21 * reproducibility across platforms. */
rand_word()22 uint32_t rand_word()
23 {
24 g_random_seed ^= g_random_seed << 13;
25 g_random_seed ^= g_random_seed >> 17;
26 g_random_seed ^= g_random_seed << 5;
27 return g_random_seed;
28 }
29
30 /* Get a random integer in range, with approximately flat distribution. */
rand_int(int min,int max)31 int rand_int(int min, int max)
32 {
33 return rand_word() % (max + 1 - min) + min;
34 }
35
rand_bool()36 bool rand_bool()
37 {
38 return rand_word() & 1;
39 }
40
41 /* Get a random byte, with skewed distribution.
42 * Important corner cases like 0xFF, 0x00 and 0xFE occur more
43 * often than other values. */
rand_byte()44 uint8_t rand_byte()
45 {
46 uint32_t w = rand_word();
47 uint8_t b = w & 0xFF;
48 if (w & 0x100000)
49 b >>= (w >> 8) & 7;
50 if (w & 0x200000)
51 b <<= (w >> 12) & 7;
52 if (w & 0x400000)
53 b ^= 0xFF;
54 return b;
55 }
56
57 /* Get a random length, with skewed distribution.
58 * Favors the shorter lengths, but always atleast 1. */
rand_len(size_t max)59 size_t rand_len(size_t max)
60 {
61 uint32_t w = rand_word();
62 size_t s;
63 if (w & 0x800000)
64 w &= 3;
65 else if (w & 0x400000)
66 w &= 15;
67 else if (w & 0x200000)
68 w &= 255;
69
70 s = (w % max);
71 if (s == 0)
72 s = 1;
73
74 return s;
75 }
76
77 /* Fills a buffer with random data with skewed distribution. */
rand_fill(uint8_t * buf,size_t count)78 void rand_fill(uint8_t *buf, size_t count)
79 {
80 for (; count > 0; count--)
81 {
82 *buf++ = rand_byte();
83 }
84 }
85
86 /* Fill with random protobuf-like data */
rand_fill_protobuf(uint8_t * buf,size_t min_bytes,size_t max_bytes,int min_tag)87 size_t rand_fill_protobuf(uint8_t *buf, size_t min_bytes, size_t max_bytes, int min_tag)
88 {
89 pb_ostream_t stream = pb_ostream_from_buffer(buf, max_bytes);
90
91 while(stream.bytes_written < min_bytes)
92 {
93 pb_wire_type_t wt = rand_int(0, 3);
94 if (wt == 3) wt = 5; /* Gap in values */
95
96 if (!pb_encode_tag(&stream, wt, rand_int(min_tag, min_tag + 512)))
97 break;
98
99 if (wt == PB_WT_VARINT)
100 {
101 uint64_t value;
102 rand_fill((uint8_t*)&value, sizeof(value));
103 pb_encode_varint(&stream, value);
104 }
105 else if (wt == PB_WT_64BIT)
106 {
107 uint64_t value;
108 rand_fill((uint8_t*)&value, sizeof(value));
109 pb_encode_fixed64(&stream, &value);
110 }
111 else if (wt == PB_WT_32BIT)
112 {
113 uint32_t value;
114 rand_fill((uint8_t*)&value, sizeof(value));
115 pb_encode_fixed32(&stream, &value);
116 }
117 else if (wt == PB_WT_STRING)
118 {
119 size_t len;
120 uint8_t *buf;
121
122 if (min_bytes > stream.bytes_written)
123 len = rand_len(min_bytes - stream.bytes_written);
124 else
125 len = 0;
126
127 buf = malloc(len);
128 pb_encode_varint(&stream, len);
129 rand_fill(buf, len);
130 pb_write(&stream, buf, len);
131 free(buf);
132 }
133 }
134
135 return stream.bytes_written;
136 }
137
138 /* Given a buffer of data, mess it up a bit */
rand_mess(uint8_t * buf,size_t count)139 void rand_mess(uint8_t *buf, size_t count)
140 {
141 int m = rand_int(0, 3);
142
143 if (m == 0)
144 {
145 /* Replace random substring */
146 int s = rand_int(0, count - 1);
147 int l = rand_len(count - s);
148 rand_fill(buf + s, l);
149 }
150 else if (m == 1)
151 {
152 /* Swap random bytes */
153 int a = rand_int(0, count - 1);
154 int b = rand_int(0, count - 1);
155 int x = buf[a];
156 buf[a] = buf[b];
157 buf[b] = x;
158 }
159 else if (m == 2)
160 {
161 /* Duplicate substring */
162 int s = rand_int(0, count - 2);
163 int l = rand_len((count - s) / 2);
164 memcpy(buf + s + l, buf + s, l);
165 }
166 else if (m == 3)
167 {
168 /* Add random protobuf noise */
169 int s = rand_int(0, count - 1);
170 int l = rand_len(count - s);
171 rand_fill_protobuf(buf + s, l, count - s, 1);
172 }
173 }
174
175 /* Append or prepend protobuf noise */
rand_protobuf_noise(uint8_t * buffer,size_t bufsize,size_t * msglen)176 void rand_protobuf_noise(uint8_t *buffer, size_t bufsize, size_t *msglen)
177 {
178 int m = rand_int(0, 2);
179 size_t max_size = bufsize - 32 - *msglen;
180 if (m == 1)
181 {
182 /* Prepend */
183 uint8_t *tmp = malloc_with_check(bufsize);
184 size_t s = rand_fill_protobuf(tmp, rand_len(max_size), bufsize - *msglen, 1000);
185 memmove(buffer + s, buffer, *msglen);
186 memcpy(buffer, tmp, s);
187 free_with_check(tmp);
188 *msglen += s;
189 }
190 else if (m == 2)
191 {
192 /* Append */
193 size_t s = rand_fill_protobuf(buffer + *msglen, rand_len(max_size), bufsize - *msglen, 1000);
194 *msglen += s;
195 }
196 }
197
198 #endif
199
