release/src/router/libevent/evutil_rand.c

   1 /*
   2  * Copyright (c) 2007-2012 Niels Provos and Nick Mathewson
   3  *
   4  * Redistribution and use in source and binary forms, with or without
   5  * modification, are permitted provided that the following conditions
   6  * are met:
   7  * 1. Redistributions of source code must retain the above copyright
   8  *    notice, this list of conditions and the following disclaimer.
   9  * 2. Redistributions in binary form must reproduce the above copyright
  10  *    notice, this list of conditions and the following disclaimer in the
  11  *    documentation and/or other materials provided with the distribution.
  12  * 3. The name of the author may not be used to endorse or promote products
  13  *    derived from this software without specific prior written permission.
  14  *
  15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  16  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  17  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  18  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  19  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  20  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  21  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  22  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  23  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  24  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  25  */
  26
  27 /* This file has our secure PRNG code.  On platforms that have arc4random(),
  28  * we just use that.  Otherwise, we include arc4random.c as a bunch of static
  29  * functions, and wrap it lightly.  We don't expose the arc4random*() APIs
  30  * because A) they aren't in our namespace, and B) it's not nice to name your
  31  * APIs after their implementations.  We keep them in a separate file
  32  * so that other people can rip it out and use it for whatever.
  33  */
  34
  35 #include "event2/event-config.h"
  36
  37 #include <limits.h>
  38
  39 #include "util-internal.h"
  40 #include "evthread-internal.h"
  41
  42 #ifdef _EVENT_HAVE_ARC4RANDOM
  43 #include <stdlib.h>
  44 #include <string.h>
  45 int
  46 evutil_secure_rng_init(void)
  47 {
  48         /* call arc4random() now to force it to self-initialize */
  49         (void) arc4random();
  50         return 0;
  51 }
  52 int
  53 evutil_secure_rng_global_setup_locks_(const int enable_locks)
  54 {
  55         return 0;
  56 }
  57
  58 static void
  59 ev_arc4random_buf(void *buf, size_t n)
  60 {
  61 #if defined(_EVENT_HAVE_ARC4RANDOM_BUF) && !defined(__APPLE__)
  62         return arc4random_buf(buf, n);
  63 #else
  64         unsigned char *b = buf;
  65
  66 #if defined(_EVENT_HAVE_ARC4RANDOM_BUF)
  67         /* OSX 10.7 introducd arc4random_buf, so if you build your program
  68          * there, you'll get surprised when older versions of OSX fail to run.
  69          * To solve this, we can check whether the function pointer is set,
  70          * and fall back otherwise.  (OSX does this using some linker
  71          * trickery.)
  72          */
  73         if (arc4random_buf != NULL) {
  74                 return arc4random_buf(buf, n);
  75         }
  76 #endif
  77         /* Make sure that we start out with b at a 4-byte alignment; plenty
  78          * of CPUs care about this for 32-bit access. */
  79         if (n >= 4 && ((ev_uintptr_t)b) & 3) {
  80                 ev_uint32_t u = arc4random();
  81                 int n_bytes = 4 - (((ev_uintptr_t)b) & 3);
  82                 memcpy(b, &u, n_bytes);
  83                 b += n_bytes;
  84                 n -= n_bytes;
  85         }
  86         while (n >= 4) {
  87                 *(ev_uint32_t*)b = arc4random();
  88                 b += 4;
  89                 n -= 4;
  90         }
  91         if (n) {
  92                 ev_uint32_t u = arc4random();
  93                 memcpy(b, &u, n);
  94         }
  95 #endif
  96 }
  97
  98 #else /* !_EVENT_HAVE_ARC4RANDOM { */
  99
 100 #ifdef _EVENT_ssize_t
 101 #define ssize_t _EVENT_SSIZE_t
 102 #endif
 103 #define ARC4RANDOM_EXPORT static
 104 #define _ARC4_LOCK() EVLOCK_LOCK(arc4rand_lock, 0)
 105 #define _ARC4_UNLOCK() EVLOCK_UNLOCK(arc4rand_lock, 0)
 106 #ifndef _EVENT_DISABLE_THREAD_SUPPORT
 107 static void *arc4rand_lock;
 108 #endif
 109
 110 #define ARC4RANDOM_UINT32 ev_uint32_t
 111 #define ARC4RANDOM_NOSTIR
 112 #define ARC4RANDOM_NORANDOM
 113 #define ARC4RANDOM_NOUNIFORM
 114
 115 #include "./arc4random.c"
 116
 117 #ifndef _EVENT_DISABLE_THREAD_SUPPORT
 118 int
 119 evutil_secure_rng_global_setup_locks_(const int enable_locks)
 120 {
 121         EVTHREAD_SETUP_GLOBAL_LOCK(arc4rand_lock, 0);
 122         return 0;
 123 }
 124 #endif
 125
 126 int
 127 evutil_secure_rng_init(void)
 128 {
 129         int val;
 130
 131         _ARC4_LOCK();
 132         if (!arc4_seeded_ok)
 133                 arc4_stir();
 134         val = arc4_seeded_ok ? 0 : -1;
 135         _ARC4_UNLOCK();
 136         return val;
 137 }
 138
 139 static void
 140 ev_arc4random_buf(void *buf, size_t n)
 141 {
 142         arc4random_buf(buf, n);
 143 }
 144
 145 #endif /* } !_EVENT_HAVE_ARC4RANDOM */
 146
 147 void
 148 evutil_secure_rng_get_bytes(void *buf, size_t n)
 149 {
 150         ev_arc4random_buf(buf, n);
 151 }
 152
 153 void
 154 evutil_secure_rng_add_bytes(const char *buf, size_t n)
 155 {
 156         arc4random_addrandom((unsigned char*)buf,
 157             n>(size_t)INT_MAX ? INT_MAX : (int)n);
 158 }
 159