/*

 * Copyright (C) 2019 by Sukchan Lee <acetcom@gmail.com>

 *

 * This file is part of Open5GS.

 *

 * This program is free software: you can redistribute it and/or modify

 * it under the terms of the GNU Affero General Public License as published by

 * the Free Software Foundation, either version 3 of the License, or

 * (at your option) any later version.

 *

 * This program 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 General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program.  If not, see <https://www.gnu.org/licenses/>.

 */

#include "core-config-private.h"

#if HAVE_SYS_PARAM_H

#include <sys/param.h>

#endif

#if HAVE_SYS_RANDOM_H

#include <sys/random.h>

#endif

#if HAVE_FCNTL_H

#include <fcntl.h>

#endif

#if HAVE_UNISTD_H

#include <unistd.h>

#endif

#include "ogs-core.h"

void ogs_random(void *buf, size_t buflen)

{

#ifdef _WIN32

    void arc4random_buf(void *buf, size_t n);

    arc4random_buf(buf, buflen);

#elif defined(HAVE_GETRANDOM)

    int rc = getrandom(buf, buflen, GRND_NONBLOCK);

    if (rc < 0) {

        ogs_log_message(OGS_LOG_FATAL, ogs_errno, "getrandom() failed");

        ogs_assert_if_reached();

    }

#elif defined(HAVE_ARC4RANDOM_BUF)

    arc4random_buf(buf, buflen);

#elif defined(OGS_DEV_RANDOM)

    int fd = -1;

    /* On BSD/OS 4.1, /dev/random gives out 8 bytes at a time, then

     * gives EOF, so reading 'buflen' bytes may require opening the

     * device several times. */

    do {

        int rc;

        if (fd == -1)

            if ((fd = open(OGS_DEV_RANDOM, O_RDONLY)) == -1) {

                ogs_log_message(OGS_LOG_FATAL, ogs_errno, "open() failed");

                ogs_assert_if_reached();

            }

        do {

            rc = read(fd, buf, buflen);

        } while (rc == -1 && errno == EINTR);

        if (rc < 0) {

            ogs_log_message(OGS_LOG_ERROR, ogs_errno, "read() failed");

            close(fd);

            return;

        }

        else if (rc == 0) {

            close(fd);

            fd = -1; /* force open() again */

        }

        else {

            buf = (unsigned char *)buf + rc;

            buflen -= rc;

        }

    } while (buflen > 0);

    close(fd);

#else

#error cannot find a method which finds a pseudo-random number

#endif

}

uint32_t ogs_random32(void)

{

#ifdef _WIN32

    uint32_t arc4random(void);

    return arc4random();

#elif defined(HAVE_ARC4RANDOM_BUF)

    return arc4random();

#else

    uint32_t rand32;

    ogs_random(&rand32, sizeof(rand32));

    return rand32;

#endif

}

#ifdef _WIN32

#define ARC4RANDOM_NO_INCLUDES

#define ARC4_LOCK_() do {} while(0)

#define ARC4_UNLOCK_() do {} while(0)

#define ARC4RANDOM_UINT32 uint32_t

#define ARC4RANDOM_NOSTIR

#define ARC4RANDOM_NOADDRANDOM

#define ARC4RANDOM_NOUNIFORM

/**

 * Stolen from libevent library.

 * https://github.com/libevent/libevent/blob/master/evutil.c

 */

void *(*volatile evutil_memset_volatile_)(void *, int, size_t) = memset;

static void evutil_memclear_(void *mem, size_t len)

{

    evutil_memset_volatile_(mem, 0, len);

}

#include "arc4random.c"

#endif