/*
 * Ouroboros - Copyright (C) 2016 - 2026
 *
 * Pseudo random generator
 *
 *    Dimitri Staessens <dimitri@ouroboros.rocks>
 *    Sander Vrijders   <sander@ouroboros.rocks>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public License
 * version 2.1 as published by the Free Software Foundation.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., http://www.fsf.org/about/contact/.
 */

#include "config.h"

#include <ouroboros/random.h>

#if defined(__APPLE__) || defined(__FreeBSD__)
#include <stdlib.h>
#elif defined(HAVE_SYS_RANDOM)
#include <sys/random.h>
#include <errno.h>
#include <stdint.h>
#elif defined(HAVE_LIBGCRYPT)
#include <gcrypt.h>
#elif defined(HAVE_OPENSSL_RNG)
#include <openssl/rand.h>
#include <limits.h>
#endif

int random_buffer(void * buf,
                  size_t len)
{
#if defined(__APPLE__) || defined(__FreeBSD__)
        arc4random_buf(buf, len);
        return 0;
#elif defined(HAVE_SYS_RANDOM)
        size_t  off = 0;
        ssize_t ret;

        while (off < len) {
                ret = getrandom((uint8_t *) buf + off, len - off,
                                GRND_NONBLOCK);
                if (ret < 0) {
                        if (errno == EINTR)
                                continue;
                        return -1;
                }
                off += (size_t) ret;
        }

        return 0;
#elif defined(HAVE_LIBGCRYPT)
        gcry_randomize(buf, len, GCRY_STRONG_RANDOM);
        return 0;
#elif defined(HAVE_OPENSSL_RNG)
        if (len == 0 || len >= INT_MAX)
                return -1;

        return RAND_bytes((unsigned char *) buf, (int) len) == 1 ? 0 : -1;
#endif
}