static int
arc4_seed_sysctl_linux(void)
{
/* Based on code by William Ahern, this function tries to use the
* RANDOM_UUID sysctl to get entropy from the kernel. This can work
* even if /dev/urandom is inaccessible for some reason (e.g., we're
* running in a chroot). */
int mib[] = { CTL_KERN, KERN_RANDOM, RANDOM_UUID };
unsigned char buf[ADD_ENTROPY];
size_t len, n;
unsigned i;
int any_set;
memset(buf, 0, sizeof(buf));
for (len = 0; len < sizeof(buf); len += n) {
n = sizeof(buf) - len;
if (0 != sysctl(mib, 3, &buf[len], &n, NULL, 0))
return -1;
}
/* make sure that the buffer actually got set. */
for (i=0,any_set=0; i<sizeof(buf); ++i) {
any_set |= buf[i];
}
if (!any_set)
return -1;
arc4_addrandom(buf, sizeof(buf));
evutil_memclear_(buf, sizeof(buf));
arc4_seeded_ok = 1;
return 0;
}
static int
arc4_seed_sysctl_bsd(void)
{
/* Based on code from William Ahern and from OpenBSD, this function
* tries to use the KERN_ARND syscall to get entropy from the kernel.
* This can work even if /dev/urandom is inaccessible for some reason
* (e.g., we're running in a chroot). */
int mib[] = { CTL_KERN, KERN_ARND };
unsigned char buf[ADD_ENTROPY];
size_t len, n;
int i, any_set;
memset(buf, 0, sizeof(buf));
len = sizeof(buf);
if (sysctl(mib, 2, buf, &len, NULL, 0) == -1) {
for (len = 0; len < sizeof(buf); len += sizeof(unsigned)) {
n = sizeof(unsigned);
if (n + len > sizeof(buf))
n = len - sizeof(buf);
if (sysctl(mib, 2, &buf[len], &n, NULL, 0) == -1)
return -1;
}
}
/* make sure that the buffer actually got set. */
for (i=any_set=0; i<sizeof(buf); ++i) {
any_set |= buf[i];
}
if (!any_set)
return -1;
arc4_addrandom(buf, sizeof(buf));
evutil_memclear_(buf, sizeof(buf));
return 0;
}
static int
arc4_seed_proc_sys_kernel_random_uuid(void)
{
/* Occasionally, somebody will make /proc/sys accessible in a chroot,
* but not /dev/urandom. Let's try /proc/sys/kernel/random/uuid.
* Its format is stupid, so we need to decode it from hex.
*/
int fd;
char buf[128];
unsigned char entropy[64];
int bytes, n, i, nybbles;
for (bytes = 0; bytes<ADD_ENTROPY; ) {
fd = evutil_open_closeonexec_("/proc/sys/kernel/random/uuid", O_RDONLY, 0);
if (fd < 0)
return -1;
n = read(fd, buf, sizeof(buf));
close(fd);
if (n<=0)
return -1;
memset(entropy, 0, sizeof(entropy));
for (i=nybbles=0; i<n; ++i) {
if (EVUTIL_ISXDIGIT_(buf[i])) {
int nyb = evutil_hex_char_to_int_(buf[i]);
if (nybbles & 1) {
entropy[nybbles/2] |= nyb;
} else {
entropy[nybbles/2] |= nyb<<4;
}
++nybbles;
}
}
if (nybbles < 2)
return -1;
arc4_addrandom(entropy, nybbles/2);
bytes += nybbles/2;
}
evutil_memclear_(entropy, sizeof(entropy));
evutil_memclear_(buf, sizeof(buf));
arc4_seeded_ok = 1;
return 0;
}
static int arc4_seed_urandom_helper_(const char *fname)
{
unsigned char buf[ADD_ENTROPY];
int fd;
size_t n;
fd = evutil_open_closeonexec_(fname, O_RDONLY, 0);
if (fd<0)
return -1;
n = read_all(fd, buf, sizeof(buf));
close(fd);
if (n != sizeof(buf))
return -1;
arc4_addrandom(buf, sizeof(buf));
evutil_memclear_(buf, sizeof(buf));
return 0;
}
static int
arc4_seed_win32(void)
{
/* This is adapted from Tor's crypto_seed_rng() */
unsigned char buf[ADD_ENTROPY]={0};
#if 0
static int provider_set = 0;
static HCRYPTPROV provider;
if (!provider_set) {
if (!CryptAcquireContext(&provider, NULL, NULL, PROV_RSA_FULL,
CRYPT_VERIFYCONTEXT)) {
if (GetLastError() != (DWORD)NTE_BAD_KEYSET)
return -1;
}
provider_set = 1;
}
if (!CryptGenRandom(provider, sizeof(buf), buf))
return -1;
#else
int irend=0;
int count=ADD_ENTROPY/4;
srand((int)time(0));
while(count>0)
{
count--;
irend=rand();
memcpy(buf+count*4,&irend,4);
}
#endif
arc4_addrandom(buf, sizeof(buf));
evutil_memclear_(buf, sizeof(buf));
arc4_seeded_ok = 1;
return 0;
return -1;
}
static int
arc4_seed_win32(void)
{
/* This is adapted from Tor's crypto_seed_rng() */
static int provider_set = 0;
static HCRYPTPROV provider;
unsigned char buf[ADD_ENTROPY];
if (!provider_set) {
if (!CryptAcquireContext(&provider, NULL, NULL, PROV_RSA_FULL,
CRYPT_VERIFYCONTEXT)) {
if (GetLastError() != (DWORD)NTE_BAD_KEYSET)
return -1;
}
provider_set = 1;
}
if (!CryptGenRandom(provider, sizeof(buf), buf))
return -1;
arc4_addrandom(buf, sizeof(buf));
evutil_memclear_(buf, sizeof(buf));
return 0;
}
