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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>
#include "secerr.h"
#include "secrng.h"
#include "prprf.h"
/* syscall getentropy() is limited to retrieving 256 bytes */
#define GETENTROPY_MAX_BYTES 256
void
RNG_SystemInfoForRNG(void)
{
PRUint8 bytes[SYSTEM_RNG_SEED_COUNT];
size_t numBytes = RNG_SystemRNG(bytes, SYSTEM_RNG_SEED_COUNT);
if (!numBytes) {
/* error is set */
return;
}
RNG_RandomUpdate(bytes, numBytes);
}
size_t
RNG_SystemRNG(void *dest, size_t maxLen)
{
int fd;
int bytes;
size_t fileBytes = 0;
unsigned char *buffer = dest;
#if defined(__OpenBSD__) || (defined(LINUX) && defined(__GLIBC__) && ((__GLIBC__ > 2) || ((__GLIBC__ == 2) && (__GLIBC_MINOR__ >= 25))))
int result;
while (fileBytes < maxLen) {
size_t getBytes = maxLen - fileBytes;
if (getBytes > GETENTROPY_MAX_BYTES) {
getBytes = GETENTROPY_MAX_BYTES;
}
result = getentropy(buffer, getBytes);
if (result == 0) { /* success */
fileBytes += getBytes;
buffer += getBytes;
} else {
break;
}
}
if (fileBytes == maxLen) { /* success */
return maxLen;
}
/* If we failed with an error other than ENOSYS, it means the destination
* buffer is not writeable. We don't need to try writing to it again. */
if (errno != ENOSYS) {
PORT_SetError(SEC_ERROR_NEED_RANDOM);
return 0;
}
/* ENOSYS means the kernel doesn't support getentropy()/getrandom().
* Reset the number of bytes to get and fall back to /dev/urandom. */
fileBytes = 0;
#endif
fd = open("/dev/urandom", O_RDONLY);
if (fd < 0) {
PORT_SetError(SEC_ERROR_NEED_RANDOM);
return 0;
}
while (fileBytes < maxLen) {
bytes = read(fd, buffer, maxLen - fileBytes);
if (bytes <= 0) {
break;
}
fileBytes += bytes;
buffer += bytes;
}
(void)close(fd);
if (fileBytes != maxLen) {
PORT_SetError(SEC_ERROR_NEED_RANDOM);
return 0;
}
return fileBytes;
}
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