release/src-rt-6.x.4708/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_set_urandom_device_file(char *fname)
  47 {
  48         (void) fname;
  49         return -1;
  50 }
  51 int
  52 evutil_secure_rng_init(void)
  53 {
  54         /* call arc4random() now to force it to self-initialize */
  55         (void) arc4random();
  56         return 0;
  57 }
  58 int
  59 evutil_secure_rng_global_setup_locks_(const int enable_locks)
  60 {
  61         return 0;
  62 }
  63
  64 static void
  65 ev_arc4random_buf(void *buf, size_t n)
  66 {
  67 #if defined(_EVENT_HAVE_ARC4RANDOM_BUF) && !defined(__APPLE__)
  68         return arc4random_buf(buf, n);
  69 #else
  70         unsigned char *b = buf;
  71
  72 #if defined(_EVENT_HAVE_ARC4RANDOM_BUF)
  73         /* OSX 10.7 introducd arc4random_buf, so if you build your program
  74          * there, you'll get surprised when older versions of OSX fail to run.
  75          * To solve this, we can check whether the function pointer is set,
  76          * and fall back otherwise.  (OSX does this using some linker
  77          * trickery.)
  78          */
  79         {
  80                 void (*tptr)(void *,size_t) =
  81                     (void (*)(void*,size_t))arc4random_buf;
  82                 if (tptr != NULL) {
  83                         return arc4random_buf(buf, n);
  84                 }
  85         }
  86 #endif
  87         /* Make sure that we start out with b at a 4-byte alignment; plenty
  88          * of CPUs care about this for 32-bit access. */
  89         if (n >= 4 && ((ev_uintptr_t)b) & 3) {
  90                 ev_uint32_t u = arc4random();
  91                 int n_bytes = 4 - (((ev_uintptr_t)b) & 3);
  92                 memcpy(b, &u, n_bytes);
  93                 b += n_bytes;
  94                 n -= n_bytes;
  95         }
  96         while (n >= 4) {
  97                 *(ev_uint32_t*)b = arc4random();
  98                 b += 4;
  99                 n -= 4;
 100         }
 101         if (n) {
 102                 ev_uint32_t u = arc4random();
 103                 memcpy(b, &u, n);
 104         }
 105 #endif
 106 }
 107
 108 #else /* !_EVENT_HAVE_ARC4RANDOM { */
 109
 110 #ifdef _EVENT_ssize_t
 111 #define ssize_t _EVENT_SSIZE_t
 112 #endif
 113 #define ARC4RANDOM_EXPORT static
 114 #define _ARC4_LOCK() EVLOCK_LOCK(arc4rand_lock, 0)
 115 #define _ARC4_UNLOCK() EVLOCK_UNLOCK(arc4rand_lock, 0)
 116 #ifndef _EVENT_DISABLE_THREAD_SUPPORT
 117 static void *arc4rand_lock;
 118 #endif
 119
 120 #define ARC4RANDOM_UINT32 ev_uint32_t
 121 #define ARC4RANDOM_NOSTIR
 122 #define ARC4RANDOM_NORANDOM
 123 #define ARC4RANDOM_NOUNIFORM
 124
 125 #include "./arc4random.c"
 126
 127 #ifndef _EVENT_DISABLE_THREAD_SUPPORT
 128 int
 129 evutil_secure_rng_global_setup_locks_(const int enable_locks)
 130 {
 131         EVTHREAD_SETUP_GLOBAL_LOCK(arc4rand_lock, 0);
 132         return 0;
 133 }
 134 #endif
 135
 136 int
 137 evutil_secure_rng_set_urandom_device_file(char *fname)
 138 {
 139 #ifdef TRY_SEED_URANDOM
 140         _ARC4_LOCK();
 141         arc4random_urandom_filename = fname;
 142         _ARC4_UNLOCK();
 143 #endif
 144         return 0;
 145 }
 146
 147 int
 148 evutil_secure_rng_init(void)
 149 {
 150         int val;
 151
 152         _ARC4_LOCK();
 153         if (!arc4_seeded_ok)
 154                 arc4_stir();
 155         val = arc4_seeded_ok ? 0 : -1;
 156         _ARC4_UNLOCK();
 157         return val;
 158 }
 159
 160 static void
 161 ev_arc4random_buf(void *buf, size_t n)
 162 {
 163         arc4random_buf(buf, n);
 164 }
 165
 166 #endif /* } !_EVENT_HAVE_ARC4RANDOM */
 167
 168 void
 169 evutil_secure_rng_get_bytes(void *buf, size_t n)
 170 {
 171         ev_arc4random_buf(buf, n);
 172 }
 173
 174 void
 175 evutil_secure_rng_add_bytes(const char *buf, size_t n)
 176 {
 177         arc4random_addrandom((unsigned char*)buf,
 178             n>(size_t)INT_MAX ? INT_MAX : (int)n);
 179 }
 180