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 <stdlib.h>
  31 #include <time.h>
  32
  33 #ifdef HAVE_WINDOWS_H
  34 #include <windows.h>
  35 #include <wincrypt.h>
  36 #endif
  37
  38 #include <pulsecore/core-util.h>
  39 #include <pulsecore/log.h>
  40 #include <pulsecore/macro.h>
  41
  42 #include "random.h"
  43
  44 static pa_bool_t has_whined = FALSE;
  45
  46 static const char * const devices[] = { "/dev/urandom", "/dev/random", NULL };
  47
  48 static int random_proper(void *ret_data, size_t length) {
  49 #ifdef OS_IS_WIN32
  50     int ret = -1;
  51
  52     HCRYPTPROV hCryptProv = 0;
  53
  54     pa_assert(ret_data);
  55     pa_assert(length > 0);
  56
  57     if (CryptAcquireContext(&hCryptProv, NULL, NULL, PROV_RSA_FULL, CRYPT_VERIFYCONTEXT | CRYPT_SILENT)) {
  58         if(CryptGenRandom(hCryptProv, length, ret_data))
  59             ret = 0;
  60         CryptReleaseContext(hCryptProv, 0);
  61     }
  62
  63     return ret;
  64
  65 #else /* OS_IS_WIN32 */
  66
  67     int fd, ret = -1;
  68     ssize_t r = 0;
  69     const char *const * device;
  70
  71     pa_assert(ret_data);
  72     pa_assert(length > 0);
  73
  74     device = devices;
  75
  76     while (*device) {
  77         ret = 0;
  78
  79         if ((fd = pa_open_cloexec(*device, O_RDONLY, 0)) >= 0) {
  80
  81             if ((r = pa_loop_read(fd, ret_data, length, NULL)) < 0 || (size_t) r != length)
  82                 ret = -1;
  83
  84             pa_close(fd);
  85         } else
  86             ret = -1;
  87
  88         if (ret == 0)
  89             break;
  90
  91         device++;
  92     }
  93
  94     return ret;
  95 #endif /* OS_IS_WIN32 */
  96 }
  97
  98 void pa_random_seed(void) {
  99     unsigned int seed;
 100
 101     if (random_proper(&seed, sizeof(unsigned int)) < 0) {
 102
 103         if (!has_whined) {
 104             pa_log_warn("Failed to get proper entropy. Falling back to seeding with current time.");
 105             has_whined = TRUE;
 106         }
 107
 108         seed = (unsigned int) time(NULL);
 109     }
 110
 111     srand(seed);
 112 }
 113
 114 void pa_random(void *ret_data, size_t length) {
 115     uint8_t *p;
 116     size_t l;
 117
 118     pa_assert(ret_data);
 119     pa_assert(length > 0);
 120
 121     if (random_proper(ret_data, length) >= 0)
 122         return;
 123
 124     if (!has_whined) {
 125         pa_log_warn("Failed to get proper entropy. Falling back to unsecure pseudo RNG.");
 126         has_whined = TRUE;
 127     }
 128
 129     for (p = ret_data, l = length; l > 0; p++, l--)
 130         *p = (uint8_t) rand();
 131 }