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

   1 /* $Id$ */
   2
   3 /***
   4   This file is part of PulseAudio.
   5
   6   Copyright 2004-2006 Lennart Poettering
   7   Copyright 2006 Pierre Ossman <ossman@cendio.se> for Cendio AB
   8
   9   PulseAudio is free software; you can redistribute it and/or modify
  10   it under the terms of the GNU Lesser General Public License as
  11   published by the Free Software Foundation; either version 2.1 of the
  12   License, or (at your option) any later version.
  13
  14   PulseAudio is distributed in the hope that it will be useful, but
  15   WITHOUT ANY WARRANTY; without even the implied warranty of
  16   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  17   Lesser General Public License for more details.
  18
  19   You should have received a copy of the GNU Lesser General Public
  20   License along with PulseAudio; if not, write to the Free Software
  21   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
  22   USA.
  23 ***/
  24
  25 #ifdef HAVE_CONFIG_H
  26 #include <config.h>
  27 #endif
  28
  29 #include <fcntl.h>
  30 #include <unistd.h>
  31 #include <errno.h>
  32 #include <string.h>
  33 #include <stdlib.h>
  34 #include <assert.h>
  35 #include <time.h>
  36
  37 #include <pulsecore/core-util.h>
  38 #include <pulsecore/log.h>
  39
  40 #include "random.h"
  41
  42 static int has_whined = 0;
  43
  44 static const char *devices[] = { "/dev/urandom", "/dev/random", NULL };
  45
  46 static int random_proper(void *ret_data, size_t length) {
  47 #ifdef OS_IS_WIN32
  48     assert(ret_data && length);
  49
  50     return -1;
  51
  52 #else /* OS_IS_WIN32 */
  53
  54     int fd, ret = -1;
  55     ssize_t r = 0;
  56     const char **device;
  57
  58     assert(ret_data && length);
  59
  60     device = devices;
  61
  62     while (*device) {
  63         ret = 0;
  64
  65         if ((fd = open(*device, O_RDONLY)) >= 0) {
  66
  67             if ((r = pa_loop_read(fd, ret_data, length, NULL)) < 0 || (size_t) r != length)
  68                 ret = -1;
  69
  70             close(fd);
  71         } else
  72             ret = -1;
  73
  74         if (ret == 0)
  75             break;
  76     }
  77
  78     return ret;
  79 #endif /* OS_IS_WIN32 */
  80 }
  81
  82 void pa_random_seed(void) {
  83     unsigned int seed;
  84
  85     if (random_proper(&seed, sizeof(unsigned int)) < 0) {
  86         if (!has_whined)
  87             pa_log_warn("failed to get proper entropy. Falling back to seeding with current time.");
  88         has_whined = 1;
  89
  90         seed = (unsigned int) time(NULL);
  91     }
  92
  93     srand(seed);
  94 }
  95
  96 void pa_random(void *ret_data, size_t length) {
  97     uint8_t *p;
  98     size_t l;
  99
 100     assert(ret_data && length);
 101
 102     if (random_proper(ret_data, length) >= 0)
 103         return;
 104
 105     if (!has_whined)
 106         pa_log_warn("failed to get proper entropy. Falling back to unsecure pseudo RNG.");
 107     has_whined = 1;
 108
 109     for (p = ret_data, l = length; l > 0; p++, l--)
 110         *p = (uint8_t) rand();
 111 }