/**
Interface to the (hopefully) good crypto random number generator.
Will use our internal PRNG if more than 40 bytes of random generation
has been requested, otherwise tries to read from /dev/random
**/
_PUBLIC_ void generate_random_buffer(uint8_t *out, int len)
{
unsigned char md4_buf[64];
unsigned char tmp_buf[16];
unsigned char *p;
if(!done_reseed) {
bytes_since_reseed += len;
/* Magic constant to try and avoid reading 40 bytes
* and setting up the PRNG if the app only ever wants
* a few bytes */
if (bytes_since_reseed < 40) {
if (urand_fd == -1) {
urand_fd = open( "/dev/urandom", O_RDONLY,0);
if (urand_fd != -1) {
smb_set_close_on_exec(urand_fd);
}
}
if(urand_fd != -1 && (read(urand_fd, out, len) == len)) {
return;
}
}
urand_fd = do_reseed(urand_fd);
done_reseed = true;
}
/*
* Generate random numbers in chunks of 64 bytes,
* then md4 them & copy to the output buffer.
* This way the raw state of the stream is never externally
* seen.
*/
p = out;
while(len > 0) {
int copy_len = len > 16 ? 16 : len;
get_random_stream(md4_buf, sizeof(md4_buf));
mdfour(tmp_buf, md4_buf, sizeof(md4_buf));
memcpy(p, tmp_buf, copy_len);
p += copy_len;
len -= copy_len;
}
}
void generate_random_buffer( unsigned char *out, int len, BOOL do_reseed_now)
{
static BOOL done_reseed = False;
static int urand_fd = -1;
unsigned char md4_buf[64];
unsigned char tmp_buf[16];
unsigned char *p;
if(!done_reseed || do_reseed_now) {
urand_fd = do_reseed(True, urand_fd);
done_reseed = True;
}
if (urand_fd != -1 && len > 0) {
if (read(urand_fd, out, len) == len)
return; /* len bytes of random data read from urandom. */
/* Read of urand error, drop back to non urand method. */
close(urand_fd);
urand_fd = -1;
do_reseed(False, -1);
done_reseed = True;
}
/*
* Generate random numbers in chunks of 64 bytes,
* then md4 them & copy to the output buffer.
* This way the raw state of the stream is never externally
* seen.
*/
p = out;
while(len > 0) {
int copy_len = len > 16 ? 16 : len;
get_random_stream(md4_buf, sizeof(md4_buf));
mdfour(tmp_buf, md4_buf, sizeof(md4_buf));
memcpy(p, tmp_buf, copy_len);
p += copy_len;
len -= copy_len;
}
}