/*

 * Copyright (c) 2007-2012 Niels Provos and Nick Mathewson

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 * 1. Redistributions of source code must retain the above copyright

 *    notice, this list of conditions and the following disclaimer.

 * 2. Redistributions in binary form must reproduce the above copyright

 *    notice, this list of conditions and the following disclaimer in the

 *    documentation and/or other materials provided with the distribution.

 * 3. The name of the author may not be used to endorse or promote products

 *    derived from this software without specific prior written permission.

 *

 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR

 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES

 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.

 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,

 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT

 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,

 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY

 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF

 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 */

/* This file has our secure PRNG code.  On platforms that have arc4random(),

 * we just use that.  Otherwise, we include arc4random.c as a bunch of static

 * functions, and wrap it lightly.  We don't expose the arc4random*() APIs

 * because A) they aren't in our namespace, and B) it's not nice to name your

 * APIs after their implementations.  We keep them in a separate file

 * so that other people can rip it out and use it for whatever.

 */

#include "event2/event-config.h"

#include "evconfig-private.h"

#include <limits.h>

#include "util-internal.h"

#include "evthread-internal.h"

#ifdef EVENT__HAVE_ARC4RANDOM

#include <stdlib.h>

#include <string.h>

int

evutil_secure_rng_set_urandom_device_file(char *fname)

{

  (void) fname;

  return -1;

}

int

evutil_secure_rng_init(void)

{

  /* call arc4random() now to force it to self-initialize */

  (void) arc4random();

  return 0;

}

#ifndef EVENT__DISABLE_THREAD_SUPPORT

int

evutil_secure_rng_global_setup_locks_(const int enable_locks)

{

  return 0;

}

#endif

static void

evutil_free_secure_rng_globals_locks(void)

{

}

static void

ev_arc4random_buf(void *buf, size_t n)

{

#if defined(EVENT__HAVE_ARC4RANDOM_BUF) && !defined(__APPLE__)

  arc4random_buf(buf, n);

  return;

#else

  unsigned char *b = buf;

#if defined(EVENT__HAVE_ARC4RANDOM_BUF)

  /* OSX 10.7 introducd arc4random_buf, so if you build your program

   * there, you'll get surprised when older versions of OSX fail to run.

   * To solve this, we can check whether the function pointer is set,

   * and fall back otherwise.  (OSX does this using some linker

   * trickery.)

   */

  {

    void (*tptr)(void *,size_t) =

        (void (*)(void*,size_t))arc4random_buf;

    if (tptr != NULL) {

      arc4random_buf(buf, n);

      return;

    }

  }

#endif

  /* Make sure that we start out with b at a 4-byte alignment; plenty

   * of CPUs care about this for 32-bit access. */

  if (n >= 4 && ((ev_uintptr_t)b) & 3) {

    ev_uint32_t u = arc4random();

    int n_bytes = 4 - (((ev_uintptr_t)b) & 3);

    memcpy(b, &u, n_bytes);

    b += n_bytes;

    n -= n_bytes;

  }

  while (n >= 4) {

    *(ev_uint32_t*)b = arc4random();

    b += 4;

    n -= 4;

  }

  if (n) {

    ev_uint32_t u = arc4random();

    memcpy(b, &u, n);

  }

#endif

}

#else /* !EVENT__HAVE_ARC4RANDOM { */

#ifdef EVENT__ssize_t

#define ssize_t EVENT__ssize_t

#endif

#define ARC4RANDOM_EXPORT static

#define ARC4_LOCK_() EVLOCK_LOCK(arc4rand_lock, 0)

#define ARC4_UNLOCK_() EVLOCK_UNLOCK(arc4rand_lock, 0)

#ifndef EVENT__DISABLE_THREAD_SUPPORT

static void *arc4rand_lock;

#endif

#define ARC4RANDOM_UINT32 ev_uint32_t

#define ARC4RANDOM_NOSTIR

#define ARC4RANDOM_NORANDOM

#define ARC4RANDOM_NOUNIFORM

#include "./arc4random.c"

#ifndef EVENT__DISABLE_THREAD_SUPPORT

int

evutil_secure_rng_global_setup_locks_(const int enable_locks)

{

  EVTHREAD_SETUP_GLOBAL_LOCK(arc4rand_lock, 0);

  return 0;

}

#endif

static void

evutil_free_secure_rng_globals_locks(void)

{

#ifndef EVENT__DISABLE_THREAD_SUPPORT

  if (arc4rand_lock != NULL) {

    EVTHREAD_FREE_LOCK(arc4rand_lock, 0);

    arc4rand_lock = NULL;

  }

#endif

  return;

}

int

evutil_secure_rng_set_urandom_device_file(char *fname)

{

#ifdef TRY_SEED_URANDOM

  ARC4_LOCK_();

  arc4random_urandom_filename = fname;

  ARC4_UNLOCK_();

#endif

  return 0;

}

int

evutil_secure_rng_init(void)

{

  int val;

  ARC4_LOCK_();

  val = (!arc4_stir()) ? 0 : -1;

  ARC4_UNLOCK_();

  return val;

}

static void

ev_arc4random_buf(void *buf, size_t n)

{

  arc4random_buf(buf, n);

}

#endif /* } !EVENT__HAVE_ARC4RANDOM */

void

evutil_secure_rng_get_bytes(void *buf, size_t n)

{

  ev_arc4random_buf(buf, n);

}

#if !defined(EVENT__HAVE_ARC4RANDOM) || defined(EVENT__HAVE_ARC4RANDOM_ADDRANDOM)

void

evutil_secure_rng_add_bytes(const char *buf, size_t n)

{

  arc4random_addrandom((unsigned char*)buf,

      n>(size_t)INT_MAX ? INT_MAX : (int)n);

}

#endif

void

evutil_free_secure_rng_globals_(void)

{

    evutil_free_secure_rng_globals_locks();

}