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 #ifdef HAVE_WINDOWS_H
  35 #include <windows.h>
  36 #include <wincrypt.h>
  37 #endif
  38
  39 #include <pulsecore/core-util.h>
  40 #include <pulsecore/log.h>
  41 #include <pulsecore/macro.h>
  42
  43 #include "random.h"
  44
  45 static pa_bool_t has_whined = FALSE;
  46
  47 static const char * const devices[] = { "/dev/urandom", "/dev/random", NULL };
  48
  49 static int random_proper(void *ret_data, size_t length) {
  50 #ifdef OS_IS_WIN32
  51     int ret = -1;
  52
  53     pa_assert(ret_data);
  54     pa_assert(length > 0);
  55
  56     HCRYPTPROV hCryptProv = NULL;
  57
  58     if (CryptAcquireContext(&hCryptProv, NULL, NULL, PROV_RSA_FULL, CRYPT_VERIFYCONTEXT | CRYPT_SILENT)) {
  59         if(CryptGenRandom(hCryptProv, length, ret_data))
  60             ret = 0;
  61         CryptReleaseContext(hCryptProv, 0);
  62     }
  63
  64     return ret;
  65
  66 #else /* OS_IS_WIN32 */
  67
  68     int fd, ret = -1;
  69     ssize_t r = 0;
  70     const char *const * device;
  71
  72     pa_assert(ret_data);
  73     pa_assert(length > 0);
  74
  75     device = devices;
  76
  77     while (*device) {
  78         ret = 0;
  79
  80         if ((fd = pa_open_cloexec(*device, O_RDONLY, 0)) >= 0) {
  81
  82             if ((r = pa_loop_read(fd, ret_data, length, NULL)) < 0 || (size_t) r != length)
  83                 ret = -1;
  84
  85             pa_close(fd);
  86         } else
  87             ret = -1;
  88
  89         if (ret == 0)
  90             break;
  91
  92         device++;
  93     }
  94
  95     return ret;
  96 #endif /* OS_IS_WIN32 */
  97 }
  98
  99 void pa_random_seed(void) {
 100     unsigned int seed;
 101
 102     if (random_proper(&seed, sizeof(unsigned int)) < 0) {
 103
 104         if (!has_whined) {
 105             pa_log_warn("Failed to get proper entropy. Falling back to seeding with current time.");
 106             has_whined = TRUE;
 107         }
 108
 109         seed = (unsigned int) time(NULL);
 110     }
 111
 112     srand(seed);
 113 }
 114
 115 void pa_random(void *ret_data, size_t length) {
 116     uint8_t *p;
 117     size_t l;
 118
 119     pa_assert(ret_data);
 120     pa_assert(length > 0);
 121
 122     if (random_proper(ret_data, length) >= 0)
 123         return;
 124
 125     if (!has_whined) {
 126         pa_log_warn("Failed to get proper entropy. Falling back to unsecure pseudo RNG.");
 127         has_whined = TRUE;
 128     }
 129
 130     for (p = ret_data, l = length; l > 0; p++, l--)
 131         *p = (uint8_t) rand();
 132 }