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

   1 /***
   2   This file is part of PulseAudio.
   3
   4   Copyright 2004-2006 Lennart Poettering
   5   Copyright 2006 Pierre Ossman <ossman@cendio.se> for Cendio AB
   6
   7   PulseAudio is free software; you can redistribute it and/or modify
   8   it under the terms of the GNU Lesser General Public License as
   9   published by the Free Software Foundation; either version 2.1 of the
  10   License, or (at your option) any later version.
  11
  12   PulseAudio is distributed in the hope that it will be useful, but
  13   WITHOUT ANY WARRANTY; without even the implied warranty of
  14   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  15   Lesser General Public License for more details.
  16
  17   You should have received a copy of the GNU Lesser General Public
  18   License along with PulseAudio; if not, write to the Free Software
  19   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
  20   USA.
  21 ***/
  22
  23 #ifdef HAVE_CONFIG_H
  24 #include <config.h>
  25 #endif
  26
  27 #include <fcntl.h>
  28 #include <unistd.h>
  29 #include <errno.h>
  30 #include <string.h>
  31 #include <stdlib.h>
  32 #include <time.h>
  33
  34 #include <pulsecore/core-util.h>
  35 #include <pulsecore/log.h>
  36 #include <pulsecore/macro.h>
  37
  38 #include "random.h"
  39
  40 static pa_bool_t has_whined = TRUE;
  41
  42 static const char * const devices[] = { "/dev/urandom", "/dev/random", NULL };
  43
  44 static int random_proper(void *ret_data, size_t length) {
  45 #ifdef OS_IS_WIN32
  46     pa_assert(ret_data);
  47     pa_assert(length > 0);
  48
  49     return -1;
  50
  51 #else /* OS_IS_WIN32 */
  52
  53     int fd, ret = -1;
  54     ssize_t r = 0;
  55     const char *const * device;
  56
  57     pa_assert(ret_data);
  58     pa_assert(length > 0);
  59
  60     device = devices;
  61
  62     while (*device) {
  63         ret = 0;
  64
  65         if ((fd = pa_open_cloexec(*device, O_RDONLY, 0)) >= 0) {
  66
  67             if ((r = pa_loop_read(fd, ret_data, length, NULL)) < 0 || (size_t) r != length)
  68                 ret = -1;
  69
  70             pa_close(fd);
  71         } else
  72             ret = -1;
  73
  74         if (ret == 0)
  75             break;
  76
  77         device++;
  78     }
  79
  80     return ret;
  81 #endif /* OS_IS_WIN32 */
  82 }
  83
  84 void pa_random_seed(void) {
  85     unsigned int seed;
  86
  87     if (random_proper(&seed, sizeof(unsigned int)) < 0) {
  88
  89         if (!has_whined) {
  90             pa_log_warn("Failed to get proper entropy. Falling back to seeding with current time.");
  91             has_whined = TRUE;
  92         }
  93
  94         seed = (unsigned int) time(NULL);
  95     }
  96
  97     srand(seed);
  98 }
  99
 100 void pa_random(void *ret_data, size_t length) {
 101     uint8_t *p;
 102     size_t l;
 103
 104     pa_assert(ret_data);
 105     pa_assert(length > 0);
 106
 107     if (random_proper(ret_data, length) >= 0)
 108         return;
 109
 110     if (!has_whined) {
 111         pa_log_warn("Failed to get proper entropy. Falling back to unsecure pseudo RNG.");
 112         has_whined = TRUE;
 113     }
 114
 115     for (p = ret_data, l = length; l > 0; p++, l--)
 116         *p = (uint8_t) rand();
 117 }