code.delx.au - pulseaudio/blob - src/polypcore/random.c

   1 /* $Id$ */
   2
   3 /***
   4   This file is part of polypaudio.
   5
   6   polypaudio is free software; you can redistribute it and/or modify
   7   it under the terms of the GNU Lesser General Public License as
   8   published by the Free Software Foundation; either version 2.1 of the
   9   License, or (at your option) any later version.
  10
  11   polypaudio is distributed in the hope that it will be useful, but
  12   WITHOUT ANY WARRANTY; without even the implied warranty of
  13   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  14   Lesser General Public License for more details.
  15
  16   You should have received a copy of the GNU Lesser General Public
  17   License along with polypaudio; if not, write to the Free Software
  18   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
  19   USA.
  20 ***/
  21
  22 #ifdef HAVE_CONFIG_H
  23 #include <config.h>
  24 #endif
  25
  26 #include <fcntl.h>
  27 #include <unistd.h>
  28 #include <errno.h>
  29 #include <string.h>
  30 #include <stdlib.h>
  31 #include <assert.h>
  32 #include <time.h>
  33
  34 #include <polypcore/core-util.h>
  35 #include <polypcore/log.h>
  36
  37 #include "random.h"
  38
  39 static int has_whined = 0;
  40
  41 static const char *devices[] = { "/dev/urandom", "/dev/random", NULL };
  42
  43 static int random_proper(void *ret_data, size_t length) {
  44 #ifdef OS_IS_WIN32
  45     assert(ret_data && length);
  46
  47     return -1;
  48
  49 #else /* OS_IS_WIN32 */
  50
  51     int fd, ret = -1;
  52     ssize_t r = 0;
  53     const char **device;
  54
  55     assert(ret_data && length);
  56
  57     device = devices;
  58
  59     while (*device) {
  60         ret = 0;
  61
  62         if ((fd = open(*device, O_RDONLY)) >= 0) {
  63
  64             if ((r = pa_loop_read(fd, ret_data, length)) < 0 || (size_t) r != length)
  65                 ret = -1;
  66
  67             close(fd);
  68         } else
  69             ret = -1;
  70
  71         if (ret == 0)
  72             break;
  73     }
  74
  75     return ret;
  76 #endif /* OS_IS_WIN32 */
  77 }
  78
  79 void pa_random_seed(void) {
  80     unsigned int seed;
  81
  82     if (random_proper(&seed, sizeof(unsigned int)) < 0) {
  83         if (!has_whined)
  84             pa_log_warn(__FILE__": failed to get proper entropy. Falling back to seeding with current time.");
  85         has_whined = 1;
  86
  87         seed = (unsigned int) time(NULL);
  88     }
  89
  90     srand(seed);
  91 }
  92
  93 void pa_random(void *ret_data, size_t length) {
  94     uint8_t *p;
  95     size_t l;
  96
  97     assert(ret_data && length);
  98
  99     if (random_proper(ret_data, length) >= 0)
 100         return;
 101
 102     if (!has_whined)
 103         pa_log_warn(__FILE__": failed to get proper entropy. Falling back to unsecure pseudo RNG.");
 104     has_whined = 1;
 105
 106     for (p = ret_data, l = length; l > 0; p++, l--)
 107         *p = (uint8_t) rand();
 108 }