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#include "random_data.h"
#include <string.h>
#include <malloc_wrappers.h>
#include <pb_encode.h>
#ifndef LLVMFUZZER
static uint32_t g_random_seed = 1234;
void random_set_seed(uint32_t seed)
{
g_random_seed = seed;
}
uint32_t random_get_seed()
{
return g_random_seed;
}
/* Uses xorshift64 here instead of rand() for both speed and
* reproducibility across platforms. */
uint32_t rand_word()
{
g_random_seed ^= g_random_seed << 13;
g_random_seed ^= g_random_seed >> 17;
g_random_seed ^= g_random_seed << 5;
return g_random_seed;
}
/* Get a random integer in range, with approximately flat distribution. */
int rand_int(int min, int max)
{
return rand_word() % (max + 1 - min) + min;
}
bool rand_bool()
{
return rand_word() & 1;
}
/* Get a random byte, with skewed distribution.
* Important corner cases like 0xFF, 0x00 and 0xFE occur more
* often than other values. */
uint8_t rand_byte()
{
uint32_t w = rand_word();
uint8_t b = w & 0xFF;
if (w & 0x100000)
b >>= (w >> 8) & 7;
if (w & 0x200000)
b <<= (w >> 12) & 7;
if (w & 0x400000)
b ^= 0xFF;
return b;
}
/* Get a random length, with skewed distribution.
* Favors the shorter lengths, but always at least 1. */
size_t rand_len(size_t max)
{
uint32_t w = rand_word();
size_t s;
if (w & 0x800000)
w &= 3;
else if (w & 0x400000)
w &= 15;
else if (w & 0x200000)
w &= 255;
s = (w % max);
if (s == 0)
s = 1;
return s;
}
/* Fills a buffer with random data with skewed distribution. */
void rand_fill(uint8_t *buf, size_t count)
{
for (; count > 0; count--)
{
*buf++ = rand_byte();
}
}
/* Fill with random protobuf-like data */
size_t rand_fill_protobuf(uint8_t *buf, size_t min_bytes, size_t max_bytes, int min_tag)
{
pb_ostream_t stream = pb_ostream_from_buffer(buf, max_bytes);
while(stream.bytes_written < min_bytes)
{
pb_wire_type_t wt = rand_int(0, 3);
if (wt == 3) wt = 5; /* Gap in values */
if (!pb_encode_tag(&stream, wt, rand_int(min_tag, min_tag + 512)))
break;
if (wt == PB_WT_VARINT)
{
uint64_t value;
rand_fill((uint8_t*)&value, sizeof(value));
pb_encode_varint(&stream, value);
}
else if (wt == PB_WT_64BIT)
{
uint64_t value;
rand_fill((uint8_t*)&value, sizeof(value));
pb_encode_fixed64(&stream, &value);
}
else if (wt == PB_WT_32BIT)
{
uint32_t value;
rand_fill((uint8_t*)&value, sizeof(value));
pb_encode_fixed32(&stream, &value);
}
else if (wt == PB_WT_STRING)
{
size_t len;
uint8_t *buf;
if (min_bytes > stream.bytes_written)
len = rand_len(min_bytes - stream.bytes_written);
else
len = 0;
buf = malloc(len);
pb_encode_varint(&stream, len);
rand_fill(buf, len);
pb_write(&stream, buf, len);
free(buf);
}
}
return stream.bytes_written;
}
/* Given a buffer of data, mess it up a bit */
void rand_mess(uint8_t *buf, size_t count)
{
int m = rand_int(0, 3);
if (m == 0)
{
/* Replace random substring */
int s = rand_int(0, count - 1);
int l = rand_len(count - s);
rand_fill(buf + s, l);
}
else if (m == 1)
{
/* Swap random bytes */
int a = rand_int(0, count - 1);
int b = rand_int(0, count - 1);
int x = buf[a];
buf[a] = buf[b];
buf[b] = x;
}
else if (m == 2)
{
/* Duplicate substring */
int s = rand_int(0, count - 2);
int l = rand_len((count - s) / 2);
memcpy(buf + s + l, buf + s, l);
}
else if (m == 3)
{
/* Add random protobuf noise */
int s = rand_int(0, count - 1);
int l = rand_len(count - s);
rand_fill_protobuf(buf + s, l, count - s, 1);
}
}
/* Append or prepend protobuf noise */
void rand_protobuf_noise(uint8_t *buffer, size_t bufsize, size_t *msglen)
{
int m = rand_int(0, 2);
size_t max_size = bufsize - 32 - *msglen;
if (m == 1)
{
/* Prepend */
uint8_t *tmp = malloc_with_check(bufsize);
size_t s = rand_fill_protobuf(tmp, rand_len(max_size), bufsize - *msglen, 1000);
memmove(buffer + s, buffer, *msglen);
memcpy(buffer, tmp, s);
free_with_check(tmp);
*msglen += s;
}
else if (m == 2)
{
/* Append */
size_t s = rand_fill_protobuf(buffer + *msglen, rand_len(max_size), bufsize - *msglen, 1000);
*msglen += s;
}
}
#endif
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