The Tor Browser: netwerk/srtp/src/crypto/rng/rand

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

     1 /*

     2  * rand_source.c

     3  *

     4  * implements a random source based on /dev/random

     5  *

     6  * David A. McGrew

     7  * Cisco Systems, Inc.

     8  */

     9 /*

    10  *

    11  * Copyright(c) 2001-2006 Cisco Systems, Inc.

    12  * All rights reserved.

    13  *

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

    15  * modification, are permitted provided that the following conditions

    16  * are met:

    17  *

    18  *   Redistributions of source code must retain the above copyright

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

    20  *

    21  *   Redistributions in binary form must reproduce the above

    22  *   copyright notice, this list of conditions and the following

    23  *   disclaimer in the documentation and/or other materials provided

    24  *   with the distribution.

    25  *

    26  *   Neither the name of the Cisco Systems, Inc. nor the names of its

    27  *   contributors may be used to endorse or promote products derived

    28  *   from this software without specific prior written permission.

    29  *

    30  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS

    31  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT

    32  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS

    33  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE

    34  * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,

    35  * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES

    36  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR

    37  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)

    38  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,

    39  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)

    40  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED

    41  * OF THE POSSIBILITY OF SUCH DAMAGE.

    42  *

    43  */

    45 #include "config.h"

    47 #ifdef DEV_URANDOM

    48 # include <fcntl.h>          /* for open()  */

    49 # include <unistd.h>         /* for close() */

    50 #elif defined(HAVE_RAND_S)

    51 # define _CRT_RAND_S

    52 # include <stdlib.h>

    53 #else

    54 # include <stdio.h>

    55 #endif

    57 #include "rand_source.h"

    60 /*

    61  * global dev_rand_fdes is file descriptor for /dev/random

    62  *

    63  * This variable is also used to indicate that the random source has

    64  * been initialized.  When this variable is set to the value of the

    65  * #define RAND_SOURCE_NOT_READY, it indicates that the random source

    66  * is not ready to be used.  The value of the #define

    67  * RAND_SOURCE_READY is for use whenever that variable is used as an

    68  * indicator of the state of the random source, but not as a file

    69  * descriptor.

    70  */

    72 #define RAND_SOURCE_NOT_READY (-1)

    73 #define RAND_SOURCE_READY     (17)

    75 static int dev_random_fdes = RAND_SOURCE_NOT_READY;

    78 err_status_t

    79 rand_source_init(void) {

    80   if (dev_random_fdes >= 0) {

    81     /* already open */

    82     return err_status_ok;

    83   }

    84 #ifdef DEV_URANDOM

    85   /* open random source for reading */

    86   dev_random_fdes = open(DEV_URANDOM, O_RDONLY);

    87   if (dev_random_fdes < 0)

    88     return err_status_init_fail;

    89 #elif defined(HAVE_RAND_S)

    90   dev_random_fdes = RAND_SOURCE_READY;

    91 #else

    92   /* no random source available; let the user know */

    93   fprintf(stderr, "WARNING: no real random source present!\n");

    94   dev_random_fdes = RAND_SOURCE_READY;

    95 #endif

    96   return err_status_ok;

    97 }

    99 err_status_t

   100 rand_source_get_octet_string(void *dest, uint32_t len) {

   102   /*

   103    * read len octets from /dev/random to dest, and

   104    * check return value to make sure enough octets were

   105    * written

   106    */

   107 #ifdef DEV_URANDOM

   108   uint8_t *dst = (uint8_t *)dest;

   109   while (len)

   110   {

   111     ssize_t num_read = read(dev_random_fdes, dst, len);

   112     if (num_read <= 0 || num_read > len)

   113       return err_status_fail;

   114     len -= num_read;

   115     dst += num_read;

   116   }

   117 #elif defined(HAVE_RAND_S)

   118   uint8_t *dst = (uint8_t *)dest;

   119   while (len)

   120   {

   121     unsigned int val;

   122     errno_t err = rand_s(&val);

   124     if (err != 0)

   125       return err_status_fail;

   127     *dst++ = val & 0xff;

   128     len--;

   129   }

   130 #else

   131   /* Generic C-library (rand()) version */

   132   /* This is a random source of last resort */

   133   uint8_t *dst = (uint8_t *)dest;

   134   while (len)

   135   {

   136 	  int val = rand();

   137 	  /* rand() returns 0-32767 (ugh) */

   138 	  /* Is this a good enough way to get random bytes?

   139 	     It is if it passes FIPS-140... */

   140 	  *dst++ = val & 0xff;

   141 	  len--;

   142   }

   143 #endif

   144   return err_status_ok;

   145 }

   147 err_status_t

   148 rand_source_deinit(void) {

   149   if (dev_random_fdes < 0)

   150     return err_status_dealloc_fail;  /* well, we haven't really failed, *

   151 				      * but there is something wrong    */

   152 #ifdef DEV_URANDOM

   153   close(dev_random_fdes);

   154 #endif

   155   dev_random_fdes = RAND_SOURCE_NOT_READY;

   157   return err_status_ok;

   158 }

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