char *TadsServerManager::gen_rand_id(void *obj)
{
/* set up a hashing buffer */
sha256_ctx s;
sha256_begin(&s);
/* add the current date/time to the hash */
os_time_t timer = os_time(0);
struct tm *tblock = os_localtime(&timer);
sha256_hash((unsigned char *)tblock, sizeof(*tblock), &s);
/* add the system timer to the hash */
long systime = os_get_sys_clock_ms();
sha256_hash((unsigned char *)&systime, sizeof(systime), &s);
/* add the object address to the hash */
sha256_hash((unsigned char *)obj, sizeof(obj), &s);
/* add the current stack location to the hash */
sha256_hash((unsigned char *)&obj, sizeof(void *), &s);
/* add some random bytes from the operating system */
unsigned char rbuf[128];
os_gen_rand_bytes(rbuf, sizeof(rbuf));
sha256_hash(rbuf, sizeof(rbuf), &s);
/* compute the hash */
unsigned char hval[32];
sha256_end(hval, &s);
/* convert it to hex, but just keep the low nybbles, for 32 digits */
char *ret = lib_alloc_str(32);
int i;
for (i = 0 ; i < 32 ; ++i)
ret[i] = nybble2hex(hval[i]);
/* null-terminate the string */
ret[i] = '\0';
/* return the allocated string */
return ret;
}
/*
* Allocate space for a string of known length, and save a copy of the
* string. The length does not include a null terminator, and in fact
* the string does not need to be null-terminated. The copy returned,
* however, is null-terminated.
*/
char *lib_copy_str(const char *str, size_t len)
{
/* if the source string is null, just return null as the result */
if (str == 0)
return 0;
/* allocate space */
char *buf = lib_alloc_str(len);
/* if that succeeded, make a copy */
if (buf != 0)
{
/* copy the string */
memcpy(buf, str, len);
/* null-terminate it */
buf[len] = '\0';
}
/* return the buffer */
return buf;
}
